Automotive Stirling Engine Development Program.19800072709_1980072709
Transcript of Automotive Stirling Engine Development Program.19800072709_1980072709
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DOE/NASA/0032-79/5
NASA CR-159744
MTI 79ASE101QT6
(HftSA-CR-159744) AUTOMOTIVE STIRLING EHGINE H80-72800DEVELOPMENT PROGRAM Quarterly Technical
Progress Report, 1 Jul. - 30 Sep. 1979(Mechanical Technology, Inc.) 165 p OnclasCSCL 10B 00/85 47U95
AUTOMOTIVE STIRLING ENGINE
DEVELOPMENT PROGRAM
QUARTERLY TECHNICAL PROGRESS REPORT
FOR PERIOD: JULY 1 — SEPTEMBER 30, 1979
Mechanical Technology Incorporated
January 1980
Prepared forNATIONAL AERONAUTICS AND SPACE ADMINISTRATION
Lewis Research CenterUnder Contract DEN 3-32
forU.S. DEPARTMENT OF ENERGYConservation and Solar Applications
Off ice of TransportationPrograms
R E C E I V E DT l F A G I U T Y
A C C E S S D E P T .
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NOTICE
This report was prepared to document work sponsored bythe United States Government. Neither the United Statesnor its agent, the United States Department of Energy,nor any Federal em ployees, nor any of their contractors,subcontractors or their employees, makes any warranty,express or implied, or assumes any legal liability or re-sponsibility for the accuracy, completeness, or usefulness
of any information, apparatus, product or process dis-closed, or represents that its use would not infringeprivately owned rights.
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DOE/NASA/0032-79/5NASA CR-159744MTI 79ASE101QT6
AUTOMOTIVE STIRLING ENGINE
DEVELOPMENT PROGRAMTECHNICAL PROGRESS REPORTFOR PERIOD: JULY 1 — SEPTEMBER 30, 1979
STIRLING ENGINE SYSTEMS DIVISIONMechanical Technology IncorporatedLatham, New York 12110
January 1980
Prepared forNational Aeronautics and Space AdministrationLewis Research CenterCleveland, OhioUnder Contract DEN 3-32
fo rU.S. DEPARTMENT OF ENERGYConservation and Solar ApplicationsOff ice of Transportation ProgramsWashington, D.C. 20545Under Interagency Agreement EC-77-A-31-1040
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TABLE OF CONTENTS
1.0 SUMMARY 1
2.0 INTRODUCTION 2
3.0 PROGRESS SUMMARIES 7
3.1 Major Task 1 - Reference Engine 8
3.1.1 Task 1.1 Initial Technology Assessment 8
3.1.2 Task 1.2 Reference Engine System Design 8
3.2 Major Task 2 - Component & Subsystem Development 13
3.2.1 Combustion and Heat Transfer Technology Development... 13
3.2.2 Mechanical Component and Drive System Development 48
3.2.3 Auxiliaries Technology Development 50
3.2.4 Controls Technology Development 51
3.2.5 Materials Development 60
3.3 Major Task 3 - Baseline Engine System (P-40) 63
3.3.1 Baseline Engine (P-40) 63
3.3.2 Facilities 70
3.4 Major Task 4 - ASE Mod I System 76
3.4.1 Heat Generating System 76
3.4.2 Preheater 76
3.4.3 Heater Head 78
3.4.4 Gas Cooler 78
3.4.5 Regenerators 78
3.4.6 Cylinder Block 82
3.4.7 Seals 82
3.4.8 Cooling Systems Development 82
3.4.9 Piston/Piston Rod Assembly 84
3.4.10 Engine Drive System 853.4.11 Air/Fuel System 85
3.4.12 Auxiliaries 853.4.13 Flow Distribution Tests 85
3.4.14 Joining Techniques 85
3.4.15 Power Control 85
3.4.16 Air Blower 903.4.17 Atomizer Air Compressor 90
3.4.18 Stirling Engine System 90
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TABLE OF CONTENTS (Cont'd.)
Page
3.5 Major Task 5 - ASE Mod II System 101
3.5.1 Endurance Test on P-40 Engine (ASE40-4) 101
3.5.2 Annular Regenerator 106
3.5.3 Seal Development Test Rig No. 1 106
3.6 Major Task 6 - Prototype ASE System Study 115
3.7 Major Task 7 - Computer Program Development 116
3.8 Major Task 8 - Technical Assistance 117
3.9 Major Task 9 - Program Management 118
APPENDIX A., 121
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LIST OF FIGURES
Figure Page
FRONTISPIECE Stirling Powered Spirit Baseline Vehicle Under
Test at Michigan International Speedway
2.0-1 Program Milestones 4
2.0-2 Program Task Schedule 5
3.1.2-1 Alternative Piston Rod Seal 10
3.1.2-2 Current Reference Engine Design 11
3.1.2-3 Reference Engine Incorporated Into X-Body Vehicle 12
3.2-1 Preheater Housing 15
3.2-2 Preheater Housing and Adjacent Components 16
3.2-3 Side View of Heater Head Quadrant 17
3.2-4 Top View of Combustor 18
3.2-5 Regenerator 19
3.2-6 Cooler 19
3. 2-7 Combustion Air Blower...., 20
3.2-8 Air Pump 21
3.2-9 Rod Assembly 22
3.2-10 Piston Seal Assembly 23
3.2-11 Gas Seal Housing Cartridges 24
3.2-12 Seal Assemblies 25
3.2-13 Fuel Nozzle 26
3.2-14 Rear View of Engine Exposing Drive Gears 27
3.2-15 Crankcase/Main Shaft 28
3.2-16 Underside of Engine 28
3.2-17 Parallel Crankshaft and Bedplate Assembly - Top View 29
3.2-18 Crankshafts Without Drive Gears 29
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LIST OF FIGURES (CONT'D.)
Figure Page
3.2.1.2-1 EGR Schematic.., 31
3.2.1.2-2 CO Levels for EGR Fractions Up to 100% 33
3.2.1.3-1 CGR Schematic 34
3.2.1.3-2 Design Pressure Drop and CGR Pumping at Idle
Conditions 35
3.2.1.3-3 CGR Bypass Valve 37
3.2.1.3-4 NOX vs. Fuel Flow Using CGR 38
3.2.1.4-1 Comparison of EGR and CGR Control Valves 39
3.2.1.4-2 Comparison of NOX Reduction Methods Using
EGR and CGR 40
3.2.1.5-1 Schematic Design of Regenerator Pressure Drop
Test Rig 45
3.2.1.6-1 Heat Flows for P-40 Opel Heating System 47
3.2.2.1-1 Materials Screening Test Rig 49
3.2.3-1 ASE Mod 1 Blower Development Test Rig (Side View) 52
3.2.3-2 Cross Sections of ASE Mod I Blower DevelopmentTest Rig 53
3.2.3-3 Dimensions of Vane Height for the Blower Design 54
3.2.4-1 Electric Actuator 57
3.2.4-2 Electro-Hydraulic Actuator 57
3.2.4-3 Sliding Rod of Hydrogen Power Control Valve 58
3.3.1.1-1 P-40 Stirling Engine No. 8 Installed in the
AMC Spirit Engine 64
3.3.1.1-2 P-40 Spirit 65
3.3.2-1 Skid #1 - Engine Cooling 72
3.3.2-2 Skid #2 - Dynamometer Cooling 72
3.3.2-3 Skid #3 - Engine/Brake Assembly 73
3.3.2-4 Skid #4 - Fuel/Air 73
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LIST OF FIGURES (CONT'D.)
Figure Page
3.3.2-5 Skid #5 - Operator Control Assembly 75
3.4.1-1 ASE Mod I Combustion Chamber with Varying Heights 77
3.4.3-1 ASE Mod I Regenerator House - Effective Stress
in N/mm2
79
3.4.3-2 ASE Mod I Regenerator House - Effective Stress
in N/mm2
80
3.4.3-3 ASE Mod I Cylinder House - Effective Stress in N/mm2.... 81
3.4.6-1 Initial and Revised Duct Plate 83
3.4.13-1 Air Preheater Flow Distribution Test Rig 86
3.4.13-2 Air Preheater Flow Distribution Test Rig 87
3.4.14-1 Fixture for Brazing the Preheater Matrix 88
3.4.14-2 Brazing Test of Preheater Matrix 89
3.4.16-1 Performance Map of the Flaff Blower 91
3.4.16-2 Performance Map of the Sunflo Blower 92
3.4.16-3 Combustion Air Blower Variator 93
3.4.16-4 Results of Combustion Air Blower Noise Tests 94
3.4.17-1 Atomizer Air Compressor with Servo Oil Pump 95
3.5.1-1 Cracked Manifold 102
3.5.1-2 Enlargement of Cracked Manifold Shown in Previous
Figure 103
3.5.1-3 P-40 Endurance Test Engine 105
3.5.2-1 P-40 with Annular Regenerator-Type Heater,Regenerators Shown 107
3.5.2-2 P-40 with Annular Regenerator-Type Heater,
One Quadrant Removed 108
3.5.2-3 Close-Up View of Annular Regenerator-Type Heater
Mounted on the P-40 Engine 109
3.5.2-4 Annular Regenerator-Type Heater, Underside View of
Quadrant 110
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LIST OF FIGURES (CONT'D.)
Figure Page
3.5.2-5 Annular Regenerator-Type Heater and P-40 Engine
Mounted on Test Skid Ill
3.5.2-6 Cross Section of Annular Regenerator in the Endurance
Engine (ASE-40-4) as Compared to Cross Section of
Regenerator in a P-40 Engine 112
3.5.3-1 Diaphragm Seal Concept 113
3.5.3-2 Diaphragm Seal Test Rig 114
LIST OF TABLES .
Table Page
3.2.1.4-1 CVS Cycle Comparison 41
3.2.1.4-2 Advantages/Disadvantages of EGR and CGR 42
3.2.1.4-3 Comparison of Mod I Blower Requirements 44
3.2.4-1 Comparison of Selected Alternative Power
Control Sys terns 59
3.3.1.1-1 P-40 Spirit Performance Compared to P-40 Opel
Performance 69
3.4.18-1 Preliminary ASE Mod I Dimensions 96
3.4.18-2 Preliminary Calculated Mod I Values for Power
and Efficiency 97
3.4.18-3 Calculated Net Power and Net Efficiencies of the
Mod I Engine as a Function of Mean Pressure and
Rotational Speed 99
3.4.18-4 Friction and Auxiliary Power Requirements Used to
Perform Net Power Calculations 100
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1.0 SUMMARY
The DOE/NASA "Automotive Stirling Engine Development Program" has been
underway for approximately eighteen months.
During this time, the program's first Stirling-powered vehicle was assembled,
tested, delivered, and displayed. This predevelopmental, demonstration vehi-
cle, an Opel sedan with a P-40 Stirling engine, was presented at the October,
1978 DOE Highway Vehicle Systems Contractors' Coordination Meeting. The
program's baseline Stirling-powered vehicle, a 1979 AMC Spirit sedan contain-
ing a P-40 Stirling engine, was displayed for the first time with a mockup
engine at the meeting in April 1979. After the April CCM, the mockup engine
was removed and the "real" engine was installed. The Spirit was then tested
by AMG and changes were made in the installation and the transmission in order
to "optimize" the vehicle/engine system with respect to performance and
emissions. The results of testing the P-40 Spirit are contained in this
report. As of the end of this quarterly period, the engine in the P-40 Spirit
was run for 139.5 hours and the vehicle odometer read 1868 miles.
During the first 18 months of the program, baseline P-40 Stirling engines wereassembled and delivered to NASA, MTI, and AM General Corporation (AMG). The
P-40 engines were tested and assembled, and subsystems and components were
developed and evaluated at United Stirling of Sweden (USS). Component efforts
at MTI are underway and are reported in this rep9rt.
A breakdown of engine and test-rig operating hours is shown:
Component Test-Rig Operating Hours (as of 9/30/79)
Check Valves 2012.0 hours
Seals 441.0 hours
Combustion Development 2899.5 hoursSeal Development Test Rig No. 1 206.0 hours
TOTAL 5558.5 hours
P-40 Engine Operating Hours (as of 9/30/79)
Opel Engine 188.0 hoursNASA Engine 48.0 hours
MTI Engine 35.0 hours
Spirit Engine 139.5 hours
At 820°C 1200.0 hours
Other Testing 102.1 hours
TOTAL 1712.6 hours
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2.0 INTRODUCTION
The Automotive Stirling Engine Development Program is directed at developing
the technology relating to the automotive application of Stirling engines.
Mechanical Technology Incorporated was selected as the prime contractor to
carry out the program, which is funded by the U.S. Department of Energy (DOE)
and administrated by the National Aeronautics and Space Administration at the
Lewis Research Center (NASA-LeRC). NASA Contract No. DEN3-32 was awarded to
MTI on March 23, 1978.
MTI is responsible for overall program management, mechanical component and
systems development, engine and vehicle testing and evaluation, computer code
development, and transfer of Stirling engine technology from Sweden to the
United States. The engine development program is based upon the extensive
technological advancements, capabilities, and background knowledge in Stirling
engines of KB United Stirling (Sweden) AB & Co. (USS), a subcontractor to MTI.
AM General Corporation (AMG), a wholly owned subsidiary of American Motors
Corporation, is the subcontractor responsible for automotive selection, design,
integration, and evaluation of Stirling engines installed in passenger cars.
The Automotive Stirling Engine Development Program consists of engine develop-
ment supported by parallel component development effort. This approach was
made possible by the existence of a baseline Stirling engine (P-40) at USS and
many hours of successful in-vehicle experience (the V4X35 in the Ford Taunus,
the P-75 Mark 1 in the Volvo light-duty truck, and the P-40 in the Opel and
the Spirit sedans).
The selected program logic recognizes the current development status and the
ultimate program goals. To achieve the program's objectives, the following
major development challenges must be met:
• High efficiency (performance) resulting in improved fuel economy.
• Acceptable initial cost and low specific weight.
The current program, as recently modified to coincide with the requirements of
the "Automotive Propulsion Research and Development Act of 1978", will consist
of the development of two generations of Automotive Stirling Engines (ASE).
ASE Mod I will be the selected concept chosen from the reference engine
concept study (Task 1) and will be improved through light-weight construction
(automotive design practice) and through system (engine/vehicle) matching.
ASE Mod II will be an upgraded version of ASE Mod I, adding performance
improvement features to ASE Mod I. Improvements will be obtained throughengine development/testing, through components and subsystems development
carried out in parallel, and from the use of improved auxiliaries and
accessories. Component and subsystem development, refinement of the external
heat system, and high temperature operation will converge upon ASE Mod II.
The final Program Objectives are to develop and demonstrate, by September
1984, an Automotive Stirling Engine System, which when installed in a 1984
vehicle, will meet the following objectives:
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1. At least a 30 percent improvement in combined cycle fuel economy
(mpg), based on EPA test procedures, over that presently predicted
for a comparable 1984 production vehicle. The reference 1984
production vehicle shall be powered by a conventional spark-ignition
engine. Both the automotive Stirling and spark-ignition engine
systems will be installed in identical model vehicles* and will
give substantially the same overall vehicle driveability and per-
formance. The improved fuel economy will be based on fuel of thesame energy content (Btu/gal). The absolute fuel economy goal will
not vary over the life of the contract.
2. Gaseous emissions and particulate levels less than the following:
NOX =0.4, HC = 0.41, CO = 3.4 g/mile and a total particulate level
of 0.2 g/mile using the same fuel economy measurements.
* It is intended that identical model vehicles be used for the
comparison. However, a difference in inertia weight between the
two vehicles is acceptable if the difference results from the
substitution of the automotive Stirling engine system for the
spark-ignition powertrain system.
The following system design objectives will also bemet:
1. Ability to use a variety of alternate fuels.
2. Reliability and life comparable with powertrains currently on the
market.
3. A competitive initial cost and a life-cycle cost no greater than
that of a comparable conventionally-powered automotive vehicle.
4. Acceleration suitable for safety and consumer considerations.
5. Noise and safety characteristics that meet the currently legislated
or projected Federal Standards for 1984.
Because of program redirection and renegotiations currently underway, the mile-
stones and schedule presented below are not approved, but are expected to be
incorporated into the new contract. Until such time, they are presented for
information only.
Program milestones are as follows: (See Figure 2.0-1)
1. ASE Mod I design freeze and assessment prior to March 31, 1980.
2. Complete dynamometer characterization and assessment of first build
of ASE Mod I prior to September 30, 1981.
3. Complete dynamometer characterization and assessment of ASE Mod 1
(updated) prior to September 30, 1982.
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4. Deliver ASE Mod I system (in vehicle) to EPA prior to September 30,
1983.
5. Complete dynamometer characterization and assessment of ASE Mod II
prior to September 30, 1983.
6. Deliver ASE Mod II system (in vehicle) to EPA prior to September
1984.
Fiscal Year
1979 1980 1981 1982 1 9 8 3 1 9 8 4
ASE Mod I Design Freeze
ASE Mod IDyno Test
Dyno Charac ter iza t ion T ASE Mod I Upra ted
I IA S E Mod I EPA Vehic le Test
l - r e
A S E M o d I I Dyno T e s t
A S E M o d I I E P A V e h i c l e T e s t
F i g u r e 2.0-1 Program M i l e s t o n e s
In order to comply with the provisions of Title III of Public Law 95-238, the
"Automotive Propulsion Research and Development Act of 1978", the MTI program
as originally presented in previously issued quarterly reports is being
redirected, rescheduled, and rebudgeted.
The current, modifi ed program consists of nine major program tasks, scheduled
over six and one-half years, as shown in Figure 2.0-2. Task 6.0 of the
original program, pertaining to the third engine generation, was eliminated
and a task titled "Prototype ASE System Study" is being planned.
Task 1; Reference Engine
This task consist of a technology assessment effort (completed) and a
technology assessment report which was written and delivered to NASA. The
development and updating of a Reference Engine System Design (RESD) which
will reflect the latest design in order to meet the final program
objectives, is a continuing effort throughout the program.
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1971 1579 1980 1981 1982 1983 1984
Components ft Subsystem Technology Development
Baseline Engine System
Task 4 ASE Mod I Engine System
5 ASE Mod II Engine System
Taik 7 Computer Program Development
Task 8 TechnicalAssistance
Taw 9 Program Management
Figure 2.0-2 Program Task Schedule
Task 2; Component and Subsystem Development
Work will be initiated in response to joint NASA/USS/MTI/AMG task force
recommendations, covering the heating system, engine mechanical seals,
systems and drives, controls, materials, accessories, and auxiliaries. Workwill be directed at improvements in Stirling engine systems for ASE Mod I
and ASE Mod II.
Task 3: Baseline Engine System (P-40)
The existing P-40 Stirling engine system will be the Program's Baseline
Engine System. Five P-40 engines will be built.
• The first engine is installed in the 1977Opel.
• The second engine has been delivered to NASA for test and evaluation.
• The third engine was delivered to MTI in April for complete engine
disassembly, documentation, reassembly, and testing.
• The fourth engine was delivered to AMG and was installed by AMG into
the 1979AMC Spirit sedan.
• The fifth engine will be delivered to MTI early in FY1980 as a spare.
Facilities are under construction at MTI for engine, vehicle, and component
test ing.
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Task 4; ASE Mod I System
This will be the first "clean sheet of paper" automotive Stirling engine
developed on the program. Design effort has started on this 4-cylinder,
square "U" configuration engine. Plans call for six engines and three
vehicles. Engine deliveries are scheduled to start early in 1981.
Tentative specifications and parameters are as follows:
Power level 58 kW
Fuel Economy 27.5 mpg Heater Tube Temperature 720°C
(AMG Spirit)
Noise < Opel Emissions To meet all
standards
Specific Weight 6-7 Ib/HP Fuel Gasoline or
diesel
Task 5: ASE Mod II System
This engine system will be an upgraded version of ASE Mod I, using newdesign concepts which have been proven prior to the ASE Mod II design
review date. Predesign is planned to start in October 1981. Plans call
for five engines and three vehicles. Engine deliveries are scheduled to
start in mid-1983.
Task 7; Computer Program Development
This task covers only those computer codes necessary for implementation of
the program. These include an engine performance code, heater system
modeling, cooling system modeling, mechanical drive system modeling, a
thermodynamic cycle nodal code, an engine transient response code, and an
engine optimization code.
Task 8: Technical Assistance
Effort will be performed as requested by the Government. This work will
relate to the scope of the total contract, and will involve demonstrations,
training, displays, and other forms of assistance.
Task 9: Program Management
This task consists of program administration, management and control,
reports, product assurance, training, and contract administration.
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3.Q PROGRESS SUMMARIES
The MTI Automotive Stirling Engine Development Program has completed 1-1/2
years of effort.
The following quarterly reports have previously been published:
Quarter Covering Period MTI Report No.
1st March 23-July 1, 1978 78ASE16QT1
2nd July 2-September 30, 1978 78ASE32QT2
3rd October 1-December 31, 1978 79ASE43QT3
4th January 1-March 31, 1979 79ASE67QT4(DOE/NASA/0032-79/2,
NASA CR 159606)
5th April - June 30, 1979 79ASE88QT5(DOE/NASA/0032-79/3,
NASA CR 159610)
This report covers the sixth quarterly period of July 1, 1979 through
September 30, 1979.
The following is a summary of each of the program's major tasks.
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3.1 MAJOR TASK 1 - REFERENCE ENGINE
This task is intended to guide component, subsystem and engine system
development. A reference engine system design will be generated and conti-
nually updated to reflect the best contemplated approaches and the latest
technology to meet the final program objectives. The reference engine system
will be the focal point to guide development, will be based on approved engine
system concepts, and will include anticipated 1985 vehicle power level and
size for equivalent spark ignition, diesel, and stratified charge engines.
A comprehensive technical assessment will be made of the present status and
level of technology of Stirling engines as candidates for automotive power
plants. This assessment will be directed at, but not limited to, the status
of United Stirling of Sweden's engine design and development technology. When
completed, the Initial Technology Assessment will be used as a basis for a
detail study and reevaluation of the overall technical program plan.
3.1.1 Initial Technology Assessment
The final camera-ready copy of the Initial Technology Assessment Report
was delivered to NASA in mid-September. The report will be sent out for
printing and will be available for distribution in mid-December. For
reference purposes, the report numbers are: DOE/NASA/0032-79/4, NASA
CR-159631, MTI 79ASE77RE2.
3.1.2 Reference Engine System Design
The USS modified driving cycle vehicle simulation computer program is
now available for use.
- The engine friction model was updated to include bearing oil-film
temperature rise.
- Correlations against motoring tests were performed.
- Mileage calculations are currently being run for different
optimized engines with alternative maximum values of speed,
pressure, and temperature. The results indicate that further
investigation is needed in order to present firm recommendations.
- Different air preheater alternatives are also being compared.
Preliminary calculations indicate that different alternatives yield
a 3% difference in mileage. Mileage is better for recuperative and
preheater alternatives, mainly due to the power requirement for the
regenerative alternatives.
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Front wheel drive feasibility studies were conducted at AMG and layout
drawings of potential interferences were made. The purpose of these
studies is to evaluate possible interference areas so that their impact
on Mod I and II design activities can be evaluated. The transmission
and drive assembly of a GM "X" body vehicle was obtained for study.
An alternative piston rodseal,
using a flexible membrane between the
cap seal and a modified Leningrader seal, was studied. Seal housings,
including connections for cycle gas (max., min., and supply), were
completed. Figure 3.1.2-1 shows this new, experimental seal system.
The regenerative air preheater for the RESD was studied and drawings
were completed. The size of the preheater has been kept within
reasonable limits by dividing the matrix into two cores placed opposite
each other. By using ceramic low expansion seal supports on the hot
side, the seals were simplified and the flexible membranes were
eliminated.
A c'esign assessment meeting was held at MTI on September 26, 1979 to
firalize the RESD and ASE Mod I vehicle specifications and to review the
current approach for the RESD. The meeting was attended by MTI/USS/-
AMC/NASA. As a direct result of this meeting, new vehicle specifica-
tions are being prepared.
Fig ire 3.1.2-2 shows the current reference engine. It has four
panllel cylinders in a square cluster, with separate regenerator
housings placed outside the cylinders. The drive mechanism consists of
two crankshafts and a main shaft connected together by a synchronizing
mechanism. The cylinder block is, at least partially, made of aluminum
and the crankcase is a light alloy casting. The pressure vessel formed
by the cylinder heads, the cylinder barrels and the piston rod seal
housings are kept together by long bolts close to the circumference;
this way only the net piston forces are transmitted down to the
crankcase. Figure 3.1.2-3 shows the reference engine as it would be
packaged into an X-body vehicle.
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Piston
CylinderPressureMPa
21,5
10,0
Kapseal
10 MPaRodScraperHydrogen
Time
seal element
Filter
Crosshead
Figure 3.1.2-1 Altern ative Piston Rod Seal
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Figure 3.1.2-2 Current Reference Engine Design
mri-19621
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Figure 3.1.2-3 Re ference Engine Incorporated into X-Body Vehicle
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3.2 MAJOR TASK 2 - COMPONENT AND SUBSYSTEM DEVELOPMENT
This task covers component and subsystem development as guided by the
knowledge already gained from the existing P-40 and P-75 Stirling engines,
from the Initial Technology Assessment effort, and from the Reference Engine
System Design work.
Components and subsystems will be developed in support of ASE Mod I and ASE
Mod II engine developments. The task will include: conceptual and detail
design analyses; hardware design, fabrication and assembly; component and
susbystem testing in laboratory test-rigs and in operating engines.
Only those activities expected to result in improvements within the time frame
of the program will be covered under Major Task 2. Advanced developments
beyond the scheduled design review date for ASE Mod I and ASE Mod II will not
be a part of this task, but may be part of the new Task 6.
The component and subsystem development task will be directed to solving the
problems associated with successful demonstration of the Stirling engine forautomotive propulsion. Experts conclude that the present performance of the
Stirling engine is sufficient to replace current internal combustion engines,
and that the reliability and life requirements can be met. They also conclude
that in order to penetrate the automotive market, engine cost and complexity
must be reduced. Therefore, high engine performance must be maintained while
reducing cost by reducing complexity, substituting easily available materials
for superalloys, reducing weight and improving individual components by
intensive and directed development.
For information/orientation purposes, photographs of some of the components of
the P-40 engine are shown in Figures 3.2-1 to 3.2-18.
3.2.1 Combustion and Heat Transfer Technology Development
The objective is to advance the state of technology of the heating
system and heat exchanger components, in terms of durability, relia-
bility, performance, cost, and fabrication technology, using the exist-
ing P-40 components as a baseline.
Work on Stirling engine combustors has been directed at simple, fixed
geometry designs, with either exhaust gas recirculation (EGR) or
combustor gas recirculation (CGR) to reduce NOX levels. Work on the
combustion system will be aimed at improving the overall life and
reliability of the components without sacrificing performance in termsof efficiency and emissions.
Fuel nozzles and fuel atomization/vaporization techniques will also be
studied to reduce cost and improve performance.
3.2.1.1 Combustion Development
The inherent advantages of the Stirling engine over the internal
combustion engines are:
1. High thermal efficiency and,hence, better fuel mileage.
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MECHANICAL
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Figure 32-1 Preheater Housing
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Exhaust PortCombustion Air Blower
Turbulator
Exhaust PortInsulation Shield
Igniter Mounting Ai r Blower Inlet
Figure 3.2-2 Preheater Housing and Adjacent Components
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Heater Tubes
Upper Half of Block Assembly
Regenerators
Pistons
Figure 3.2-3 Side View of Heater Head Quadrant
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Figure 3.2-4 Top View of Com bustor
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Figure 3.2-5 Cooler
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Figure 3.2-6 Regenerator
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Figure 3.2-7 Combustion Air Blower
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Figure 3.2-8 Air Pump
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Piston Rod .
Slipper
Connecting Rod
Figure 3.2-9 R od Assembly
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fillMECHANICALTECHNOLOGY
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Figure 3.2-10 Piston Seal Assembly
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MECHANICAL
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Figure 3.2-11 Gas Seal Housing Cartridges
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Main Seal Housing
Backers Used in Cap
Seal Assembly
Figure 3.2-12 Seal Assemblies
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Figure 3.2-13 Fuel Nozzle
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Main Shaft
Drive Gears
Figure 3.2-14 Rear View of Engine Exposing Drive Gears
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Figure 3.2-15 Crankcase/Main Shaft
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Figure 3.2-16 Underside of Engine
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pressorting Point
I Pump
Figure 3.2-17 Parallel Cr an ks haf t and Bedplate Assembly — Top View
Figure 3.2-18 Cra nk sh afts without Drive Gears
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2. Low pollution product.
3. Ability to burn a wide variety of fuels.
Although the Stirling engine combustors do indeed produce low
carbon monoxide (CO) and very low total hydrocarbons (HC), the
nitrogen oxides (NOX) have been higher than that specified by the
EPA 1984 objectives. The reason is simple: A high efficiency
combustor operating at near stoichiometric fuel/air ratios willproduce high gas temperatures; these high temperatures in the
presence of and 02 will produce NOX.
Some of the methods of inhibiting the formation of NOX are:
1. Withdraw heat from the burning gas, thus keeping it cooler.
2. Reduce the oxygen content so that there are fewer 0-atoms
to react with the N-atoms.
3. Burn with a rich or lean mixture to keep the temperature
down.
All three of these methods are used in exhaust gas recirculation
(EGR) and combustion gas recirculation (CGR)methods. The burning
mixture, which contains about 25% excess air, is operating in the
lean stoichiometric region; some heat is withdrawn from the
burning gas by radiators to the heater tubes; and the recirculated
exhaust gas (EGR or CGR) reduces the 0-atom concentration and
flame temperature.
In the "standard" engine, the exhaust gas is discharged after
passing through the preheater. In the EGR system, some fraction
of the exhaust gas is introduced into the combustion air justupstream of the blower. In the CGR system, the blower pressure is
increased to produce a high velocity jet which is then used as a
jet ejector pump to recirculate a portion of the combustion gas
before it passes through the preheater.
The question to be resolved is: Is there a clear-cut advantage to
EGR or CGR?
3.2.1.2 The EGR system
The EGR system is shown in the block diagram of Figure 3.2.1.2-1.
Note that the Burner Air Flow Control also permits recirculation
of flow from the blower if there is more than is needed.
Tests were made to determine the amount of NOX reduction with
specified quantities of EGR. EGR levels up to 90% showed marked
reductions in NOX. A preliminary objective of 50 to 55% recircu-
lated gas was selected as a reasonable value for evaluating EGR
and CGR.
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014-1
•U Cfl
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The % EGR and CGR may be defined as follows:
Mass of recirculated gas
% EGR and CGR = x 100
Mass of inlet air
Volume of recirculated gas
% EGR and CGR = x 100
Volume of inlet air
The volume of recirculated gas and inlet air can be determined by
exhaust gas and combustor inlet (air plus gas) analysis for either
CC>2 or 02 volume fraction.
Tests were made with the EGR system, using a simple flow
restriction device to control percent of EGR. The test results
showed that this device resulted in a variation of percent EGRwith power level. There was a sharp rise in EGR percent at low
power, which caused combustion to become unstable. This was
remedied by installing an on-off EGR valve, which was actuated
from a power level control, so that EGR was turned off at low
power levels. This was still not satisfactory to reach the
objective of having a control which exhibits a "flat response" of
EGR to power level.
Finally, a proportionally operated valve was used, which produces
a much better response except for the very low power end where
some hysteresis was noted. The EGR percent, however, was low but
an adjustment has been made, and the valve will be tested at 50-55percent EGR.
CO level is not a concern for this combustor design. Measured CO
levels for EGR fractions up to 100% are shown in Figure 3.2.1.2-2.
For a range of fuel flows from 1 to 3 grams/sec, the CO content
did not exceed 100 ppm. Since the EPA maximum allowable level is
about 1200 pp m, CO is not a problem with these engines.
3.2.1.3 The CGR System
The CGR system is shown in in the block diagram of Figure 3.2.1.3-1.
The principal difference between CGR and EGR is that the hot gas
is not required to pass through the preheater, d ucting, or blower.
This, in itself, red uces the loading on the preheater and blower
in addition to reducing the size of the piping needed to carry the
gas. A CGR bypass valve is shown, which reduces the pressure loss
in the system at high power levels by bypassing part of the gas
around the high-pressure loss ejector.
The ejector action is shown for one operating condition (idle) in
Figure 3.2.1.3-2. A high velocity jet is produced by reducing the
air flow area from the blower, which causes increased blower-air
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8
o00 I
s
Q.3
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,/r£rt •**
or «
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Pressure Drop
Required For
Jet Pumping
Figure 3.2.1.3-2 Design Pressure Drop and CGR Pumping at Idle Conditions
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pressure. The static pressure at the jet exit drops, creating a
low pressure zone into which the exhaust gas flows. The exhaust
gas is then entrained by momentum exchange in the tube, the static
pressure rises, and the gas mixture is injected into the combus-
tor. The CGR valve is shown in Figure 3.2.1.3-3. The gas bypass
is controlled by rotating the upper portion of the valve, which
regulates the alignment of the flow ports at the lower end. The
control is set to start opening the valve at the maximum CVS cycle
power. At maximum power, the valve cuts pressure drop by more
than half, while the CGR quantity drops from near 50 percent down
to less than 5 percent.
Data showing reduced NOX, using CGR, are shown in Figure 3.2.1.3-4i
The data were from combustor rig tests where three different
ejector sizes were used. The general trend is for lower NOX at
higher fuel flow, or higher power level. While the data is consi-
derably scattered , all of the NOX values at fuel flows higher
than 1 gram/sec lie within the EPA objectives.
3.2.1.4 Comparison of EGR and CGR Performance
Data for Stirling engine number ASE40-1 and ASE40-7 (P-40 Nos. 1
and 7) with the on-off EGR valve, provid e an erratic NOX emissions
trend which does not appear to be satisfactory for the EPA goal;
however, data from ASE40-5 in the Opel, for two tests, show that
the CVS cycle NOX was lower than the EPA goal. The new EGR valve
with proportional control has the potential for better NO X
performance than the on-off valve. Further dev elopment tests of
this valve are being planned.
A comparison of the EGR and CGR control valv es is shown in Figure
3.2.1.4-1, where percent EGR or CGR is plotted versus fuel flow.
The difference in purpose and effect of the EGR and CGR control
valves is clearly shown. NOX prod uction, using these same valves,
is shown in Figure 3.2.1.4-2. Also shown is the anticipated NOX
performance for the new proportionally-controlled EGR valve. This
plot indicates that the new EGR valve may perform better in NO X
reduction than either the on-off EGR valve or the newer CGR valve;
however, this anticipated result must be confirmed in testing.
Table 3.2.1.4-1 contains a comparison of EGR and CGR with the
"standard" (no EGR or CGR) engine. The "hot end" efficiency ( nB)
for the standard engine and CGR engine are about equal; however,
about 2.28 percent of ^3 is lost in the EGR system, mainly inpreheater losses. Heater head losses are about equal for CGR and
EGR. The net effect is approximately a 3 percent loss in the EGR.
compared to CGR, or about 1 mpg.
Table 3.2.1.4-2 shows a comparison of the advantages and
disadvantages of CGR versus EGR. CGR has already been developed
to an operating stage (over 500 hours), but development is not
completed. Aft er completion, CGR is anticipated to improve gas
mileage by 1 mpg. This anticipated improvement is based on engine
system calculations.
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Figure 3.2.1.3-3 CGR Bypass Valve
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©
0
©
Fuel m,. g/ser
Figure 3.2.1.3-4 NOx Versus Fuel Flow Using CGR
IHHJ
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Idle Max Power
100
80
60
o
8w 40
20
Oper. Range
CVS Cycle
EGR (P-40 No. 5 in Opel
USS 78-0068C)
CGR
CGR Bypass
Opens
2 3
Fuel Flow, g/seo
Figure 3.2.1.4-1 Comparison of EGR and CGR Control Valves
MCCHAMCU
TtCHNOLOGV
INCOHPOHATtD-39-
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6r
M3
w
EGR With
On-Off
Valve
C C ; R w i t hB y p a s s
Idle CVS Cycle
Max
Power
2 3
Fuel fn, g/sec
Figure 3.2.1.4-2 Comparison of NOx Reduction Methods Using EGR and CGR
MECHANIC*!.
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n B H E A T E R H E A D & P R E H E A T E P E F F .
A n B P R E H E A T E R P E M A L T Y
A n B H E A T E R H E A D P E N A L T Y
1 C O M B U S T OR
R E L A T I V E HB
M PG C H A N G E - M E T R O
- H I G H W A Y
- M E T R O & H I G H W A Y
NO
E G R / C G R
86.17
-
-
9 9 . 9
1.0
REF
RE F
RE F
EGR
83.77
2.28
.12
9 9 . 9
.97
- .8
-1.1— 9
CGR
86.05
-
.12
9 9 . 9
1.0
-
—
Table 3.2.1.4-1 CVS Cycle Comparison
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ADVANTAGES DISADVANTAGES
EGR
1. An existing system that reduces
NO X
2. Variable EGR valve has potential
for fhrther NOX reduction
_ C G R
1. Does not require gas cooling to
protect blower
2. Smaller air ducting to blower
3. 37 mpg improvement over EGR
( 1
1. NOX value is marginal to meet
EPA limits
2. Reduced blower life from hot
hot gases
3. Variable EGR valve still under
development
1. By-pass valve development not
complete
2. Complex combustor shape for
manufacturing
3. NOX still marginal
4. Engine tests not yet made
Table 3.2.1.4-2 Advantages/Disadvantages of EGR and CGR
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A further comparison of EGR versus CGR and the "standard engine
combustor" with respect to blower requirements, is shown in Table
3.2.1.4-3. A high efficiency (72.5%) blower was assumed to be
used. For CGR, a large increase in pressure loss is shown for the
combustor, mainly caused by the ejector pressure needed for jet
pumping.
However, the preheater A P is significantly lower for the CGR
system leading to approximately the same system P as the EGR
system. In addition, there is a decrease in blower air flow
because with a CGR system, the blower does not have to handle the
recirculated gases. The net result is a decrease in blower power
requirement for CGR relative to EGR.
The following conclusions may be drawn relative to EGR and CGR:
1. Present EGR reduces NO by a large amount, yet NOX emission
is still borderline based on EPA requirements.
2. The variable EGR valve may produce lower NO X, but more
testing and development are required.
3. Analysis shows 3 percent or 1 mpg improvement of CGR over
EGR, mostly from preheater performance.
4. Continued development of the CGR bypass valve is needed,
although the present tested valve life is more than 500
hours.
5. EGR and CGR can use the same preheater and the same blower
could be used.
6. NOX reduction by EGR and CGR is about the same, and both are
marginal for EPA requirements.
3.2.1.5 Heat Exchanger Development
During July 1979, the primary emphasis of the heater head/regene-
rator development program was in designing a regenerator pressure
drop test rig. A schematic design for this rig is shown in Figure
3.2.1.5-1.
The system consists of a dry lubricated compressor, heat removal
and surge tank assemblies, a heater, and a test section. The testsection will have pressure taps and thermocouples to measure the
gas properties at the inlet and exhaust of the regenerator. The
test section will also contain a flow straightener, to establish
slug flow conditions at the regenerator inlet.
Using nitrogen, the rig has been sized to give pressure drop
measurements for the engine operating range of Reynolds number
from 10 to 200. The high volumetric flow rates associated with
the higher Reynolds nunbers presents a d ifficult design problem
because of the size of the equipment and its high cost. By using
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For 1200 Plate Preheater
Combustor AP, Pa
Preheater AP
Heater H e a d A P
A /F Control & Man.
T O T A L
Blower Efficiency
Blower Power, Watts
I D L E
m f =4 g/s
NO
E G R/ CG R
6
134
10
2 2
17 2
2 2 %
25
E G R
13
200
16
29
258
317,
48
CGR
9 7
135
13
2 2
2 6 7
2 2 %
39
M A X . P O W E R
m f = 5.0
N O
EGR/ CGR
580
1680
265
2 9 6 6
5491
7 2 . 5 %
5 7 2
EGR
1255
2870
519
3700
8344
7 2 . 5 %
1510
C G R
3235
1680
265
2966
8146
72 . 5%
848
Table 3.2.1.4-3 Comparison of MOD I Blower Requirements
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S
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nitrogen and designing a closed cycle system operating at 10 to 15
atmospheres, actual operation can be simulated with a moderately
priced system.
Sizing of components for the regenerator pressure drop test rig
was initiated and price quotations were requested from several
manufacturers. To meet requirements, the following specificationswere placed on the compressor:
• Dry lubrication - The compressor must be dry lubricated to
prevent contamination of the regenerators and possible
degradation of the heat transfer surfaces.
• Flow specification - The compressor must continuously deliver
up to 100 standard ft.3 /min. (SCFM) of helium or nitrogen
across a pressure differential of 20 psi.
Formulation of a development program for the heater head has begun.
The initial definition for this effort focused on development of a
mathematical model for the tubular P-40 heater head. This work will
be used to formulate a test program by defining critical test
parameters, test hardware, and instrumentation. The mathematical
model will also provide a basis for validating test results and
projecting improvements for new designs.
3.2.1.6 Heat Flows for P-40 Opel Heating System (Engine ASE40-5)
The heat flows were determined at half load and heater temperatures
of 720°C and 820°C, for the heat flow Qj through Q12, as shown in
Figure 3.2.1.6-1. Fuel flow was 2 g/s, air excess factor was 1.38,
and EGR was 50% of air flow. The results are as follows:
Symbol Heat Flow from: to Watts at Watts at
720°C 820°C
Q! Preheated air: Surroundings 335 387
Q2 Exhaust gas: Surroundings 497 570
Qj Inlet air: Surroundings 121 133
Q^ Preheated air: Exhaust gas 58 68
Q5 Preheater: Exhaust gas 126 148
Qg Combustion gas after heater:
Preheater 289 344
Qy Combustion gas after heater:
Inlet air 113 133
Qg Combustion gas before heater:
Engine block 26 27
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Figure 3.2.1.6-1 Heat Flows for P-40Opel Heating System
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Symbol Heat Flow from: to Watts at Watts at
_ _ 720°C 820"C
Qo Combustion gas between heater:
Engine block 26 29
Combustion gas after heater:Engine block 33 38
Fuel injector: Surroundings 249 286
Ignitor: Surroundings 71 81
Q2 and Q^ do not affect the efficiency of the heating system. The sum
of Q1 and Q4 - Ql2is 1326 Wattsa
t 720°C and 1541 Watts at 820°C.
3.2.2 Mechanical Technology Development
The objective is to advance the technology of mechanical drives and
mechanical components using the existing P-40 engine as the baseline.
The drive system presents a major development challenge in terms of
establishing design simplicity. It is clear that this area must be
addressed in terms of performance versus cost. It is planned to
emphasize the development of combination drive/control schemes. Basic
mechanical design calculations will also be performed on the existing
drive system to reduce losses and improve performance. Lubrication
techniques will be studied. Bearing design and losses associated with
the applied loads will be critically evaluated. Thermal effects will be
identified. For the improved designs resulting from the work the
relation to life and reliability will be studied.
3.2.2.1 Materials Screening Test Rig
The drive unit motor for the Materials Screening Test Rig was
received; the rig (shown in Figure 3.2.2.1-1) was assembled and it
is ready for testing.
Sample test coupons and seal test samples were prepared. After the
initial checkout operation of the materials screening tester, the
crosshead bearing failed. This bearing is a linear ball bushing.
The shaft was reground and a bearing bronze bushing was substituted
for the linear ball bushing. Initial tests appear to be satisfactory.
3.2.2.2 Workhorse Test Rig
A design review on the workhorse rig was held at MTI. The major
emphasis was on cost reduction. There were three major decisions
made as a result of this meeting:
- Design test heads will be able to evaluate four seal elements
per test head instead of two elements per test head. This
concept, which will double the effectiveness of each test
head, has already been incorporated into the layouts.
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- Current thinking is that three engine blocks should befabricated into the workhorse test rig. Each block wouldcarry three test heads and test twelve seal elements.
- The three engine blocks would be used as follows: one for
main seal tests, one for cap seal tests, and one for piston
ring tests. Four test heads would be available for each
block, so that one test head would be readily available incase another test head fails.
These three decisions are expected to reduce equipment cost by a
factor of more than two, and will be compatible with the available
budget.
The design layouts of the test heads for the Workhorse Seal TestRig were completed for piston rings, cap seals, and main seals.
- Procurement of a hydrogen leak detector was approved by
NASA.
- A Chevrolet 6-cylinder, 250 cubic inch engine block wasselected for the drive unit and base of the workhorse test
rigs.
- Preliminary schematics of the hydrogen gas system and of the
nitrogen leak detector gas system were prepared.
- An internal design review on the workhorse rig was held onAugust 14; actions items recommended at the meeting were
completed.
3.2.2.3 Exploratory Test Rig
Design layout activity on the exploratory tester, which is alsothe pumping ring test vehicle, was initiated. Orders were placed
for the crankcase castings and for the crankshaft casting for thedrive units. The design layout of this rig is expected to be
completed in October, and an internal design review will be held.
3.2.2.4 Engine Drive System
A meeting was held at Ricardo Consulting Engineers Ltd., todiscuss the noise generation in the P-40 engine. Results of the
Ricardo work were reported to NASA at a meeting at MTI on ThursdaySeptember 27th, and will be reported at the DOE Contractors
Coordination Meeting (CCM) on October 23, 1979. A copy ofRicardo's CCM paper is included in Appendix A of this report.
3.2.3 Auxiliaries Technology Development
The objective is to advance the existing technology on the baseline P-40auxiliaries towards the specific goals of durability, reliability,
performance, weight and cost, in order to meet the final program
objectives.
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Considerations of the auxiliary equipment required by this engine, and
therefore the parasitic losses associated with this equipment, can
provide a siginificant payback in terms of performance and cost. It will
be necessary to define the engine requirements and to develop an
improved combustion air blower and power control hydrogen compressor for
minimum losses. The remainder of the auxiliaries are common components
to internal combustion engines; however, integration with the engine
must also be provided with minimum losses. A detailed study of the
engine cooling system must be addressed. Improvements in this area couldbe derived from innovative heat transfer system design and development.
The design of the Mod I Blower Development Rig was completed at MTI.
Figure 3.2.3-1 is a schematic drawing of the blower rig, and Figure
3.2.3-2 shows the three cross sections labeled in Figure 3.2.3-1. A
speed of 28,000 rpm was selected, based on the maximum efficiency
attainable with the bearing design. The procurement of parts for the
Mod I Blower Development Rig was initiated and will continue.
The Mod I combustion air blower bearing and rotor dynamics analysis was
completed.
- The analysis indicates that USS bearing design has adequate life if
the temperature of the grease is not more than 150°C. Andox "C" or
Multifax All Purpose grease is recommended. The blower environ-
mental temperature must be measured and logged, in order to verify
the conclusion drawn from the analysis.
- A pressed ribbon-type cage, which is currently used in USS bearing
design, may be adequate; however, a significant improvement in cage
life margin can be acquired. MTI recommended that a Barden
201SSTX1 bearing (with phenolic and aluminum cages) be considered
for this design.
An assessment of the blower design for EGR/CGR options indicates that a
simple modification of vane height can accommodate both options, as
shown in Figure 3.2.3-3. A rotor with a larger vane height will be
obtained so that it will be compatible with either concept.
3.2.4 Controls Technology Development
The objective is to advance the technology level of the current P-40
engine control system in order to meet specific system and program
objective requirements. The effort will also include a study of alter-
native concepts of control.
The drive/power control system components present a major development
challenge in terms of establishing design simplicity. Present engine
technology uses a crank-type drive system with a power control system
separate from the drive mechanism, and is based on reducing and increa-
sing the pressure level within the engine by hydrogen release and addi-
tion. A hydrogen compressor is employed to pump up the engine pressure
levels as required. This system has been perfected, and presently
provides adequate power control and engine response; however, the com-
plexity of the system is of major concern in both reliability and cost.
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EGR Flow
CGR Flow
177 mm. (7.0") Limit
Figure 3.2.3-3 Dimensions of Vane Height for the Blower Design
30772
MECHANICAL
TECHNOLOGY
INC OR P OR ATED
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In conjunction with the drive/power control, it is critical that one
considers the air/fuel control. As the engine power requirements are
varied, this control must adjust to maintain constant heater wall
temperature at variable heat input. Presently, the system air flow is
modulated by a temperature signal to a throttle valve, while fuel flow
is modulated by a fuel/air controller located in the fuel line. The
amounts of both fuel and air must be regulated to maintain temperature,while the mass flow ratio of these fluids must be maintained constant to
provide a proper ratio. This requires a complex electronic system and
precise measurement technology in order to provide adequate control.
It is planned to study these control requirements in detail, in terms of
sensor design and instrumentation miniaturization. New concepts will be
evaluated and,where practical, hardware experimentation will be
conducted.
Simplified computer analysis and modeling of certain control processes,
such as timed supply, dump, and dump short-circuiting, is underway. The
first-order Stirling engine code (ORDER 1) is being reviewed for possibl
modifications and additions so that it may be used in the quasi-steadyengine/control system simulation for the P-40.
Hydrogen solenoid valve design reports have not yet been received from
Valcor Engineering Corporation. These valve designs are intended to be
low cost, modular alternatives to the present compressor short-circuitin
valve, hydrogen bottle shut-off valve, and emergency gas dump valve
presently on the P-40 engine.
The test rig mounting has been completed for preliminary static/dynamic
operation of the piezoceramic actuator for the advanced hydrogen control
valve. The benefits and objectives to be derived in developing an
electrical actuating mechanism for the hydrogen control valve have notbeen fully identified. This information will form the basis for furtherwork on this task. Figure 3.2.4-1 shows an electric actuator. Figure
3.2.4-2 shows an electro-hydraulic actuator, and Figure 3.2.4-3 shows
the rod of the hydrogen power control valve.
To aid in planning, a preliminary comparison of selected alternative
power control systems has been prepared, and is shown in Table 3.2.4-1.
• It is concluded from Table 3.2.4-1 that benefits from a fixed-
charge power control system warrants its development and evaluation
for comparison with the current MPC system.
• Although three fixed-charge systems hold interest, additional
analysis and evaluation will be required before a preference can be
supported.
Preliminary evaluation of the constant stroke, variable displacement,
power control concept continued. Limited engine performance calcula-
tions support the feasibility of specifying both positive and negative
torque by changing one variable: the phase angle. Layout studies
indicate that it is feasible to integrate this method of control into
USS-type engines. Doing this will allow control development to proceed
independently. The constant-stroke variable-displacement system is a
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Figure 3.2.4-1 Electric Ac tua tor
Figure 3.2.4-2 Electro-Hydra ulic Actuator
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Figure 3.2.4-3 Sliding Rod of Hydrogen Power Control Valve
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Engine Hydrogen Charge
Relative Vehicle Hydrogen Charge
Relative Hydrogen Compression Energy
Vehicle Charging Pressure
Typical Engine Hydrogen Relative
Pressure
Separate Engine Braking Circuit
Hydrogen Valves Required for
Power Control
Hydrogen Valves Required for Engine
Braking
Open-loop Power Control Possible
Emergency H_ Pump to Storage
Compatible with USS Engine Design
Insensitive to Debris in Working
Cycle
Decreased Axial Conduction Loss
Reduced Driveaway Time
Reduced Cold Start Fuel Penalty
Immediate Stoppage of Engine Without
Rundown
Piston Dome (& Dome Volume)
Eliminated
Hybrid (with MFC) Feasibility
MPC
variable
1
1
1
0.25
yes
yes
yes
no
no
yes
no
no
no
no
no
no
-
Variable
Stroke
fixed
+ 0.5
-•0.5
* 0.25
1
yes
no
yes
yes?
yes
no
yes
no
no
no
no
no
-
Diagonal
Phase
Shift
fixed
0.5
./•0.5
0.25
0.8
no
no
no
no
yes
yes
yes
no
no
no
no
no
highest
Bypass
fixed
0.5
-•0.5
•"0.25
1
yes
yes
yes
yes
yes
no
yes
yes
yes
yes
yes
yes
-
Table 3.2.4-1 Comparison of Selected Alternative Power Control Systems
MECHANICAL
TECHNOLOGYINCORPORATED -59-
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fixed-charge control system, which eliminates check valves, the hydrogen
compressor, and other control valves.
A Controls Task Force meeting (MTI/USS/NASA) was held at MTI on August
29-30, 1979. The key role of the Task Force in recommending development
strategy and evaluating progress was emphasized. The NASA and USS
members will review and critique MTI's proposed controls developmenteffort, and all members will review the control aspects of the vehicle
and engine specifications and will critique it for completeness and
acceptability.
The estimated costs of candidate transducers from interested vendors
ranges from $5 to $50. The cost of current pressure and position trans-
ducers are $1000 and $200 respectively. At the August, 1979 Control
Task Force meeting, it was recommended that MTI develop environmental
specifications and a testing program prior to formal quotation and
procurement of alternate transducers.
The relative performances of microprocessor products of Texas Instru-ments Inc. and Intel Corp. , which are being considered for use in the
digital electronic conversion, were assessed and were found to be
technically similar, and either system would do an adequate job.
Dynamic and step-response testing of a piezoelectric transducer was
completed at loadings of 0, 200, and 400 pounds. Results indicate that
published data for piezoelectric materials may be used to predict
performance.
An alternate version of a combustion-driven air blower was identified at
MTI. This blower concept has the potential of decreasing fuel
consumption and simplifying combustion control. The combustion driven
air blower conceptual idea has progressed through several cycles. The
current concept appears to be feasible, but has not been sized t,o give
the required flow output or checked for packaging feasibility.
3.2.5 Materials Developm ent
The objective of this task is to advance the technology of materials in
the Stirling engine in terms of durab ility, weight, cost and fabrica-
tion, using P-40 components as a baseline.
The heater head is probably the most important component in terms of
cost, mass production, and performance. It represents the greater
challenge to the designer because of the inherent constraints imposed
by the engine system. The heater head material must exhibit excellent
oxidation resistance, have excellent creep strength at high temperature,
have excellent thermal stress characteristics to preclude fatigue
failure, have desired thermal conductivity properties, and be immune to
hydrogen diffusion and materials embrittlement. In add ition, the heater
head nust be able to be mass-produced at a low cost.i
The potential to reduce weight and cost throughout the engine by
material substitution will also be studied.
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3.2.5.1 Heater Tubes
MTI has ordered seamless tubing of Inconel 625 and Inconel X-750
from Uniform Tubes, Inc. Uniform Tubes, Inc. has expressed a
willingness to produce tubing of these alloys in the required
diameter, provided the drawings and schedules are supplied. Tube
Methods and Handy & Harman Tube Division have also been contacted.
Material can be procured from Carpenter Technology Inc. (Reading,
Pennsylvania) in the desired quantities.
A vendor was found for fabricating 19-9 DL tubing and Incoloy 901
tubing. Tube Methods (Bridgeport, Pa.) agreed to produce the
heater tubing from 0.750" diameter tubing produced by deep drilling
of rod. The deep drilling will be performed by Nassau Tool Co.
(West Babylon, N.Y.) or Clark and Wheeler (Los Angeles, Calif.).
A literature review on fatigue and creep failure in tubing was
initiated. The objective of this review is to relate tube
lifetime to uniaxial creep and fatigue strengths; this may lead to
a more thorough understanding of tube failures.
Work on assessing the creep and fatigue failure mechanisms in
heater tubes was postponed in September in order to accomplish
more pressing problems related to engine component procurement.
Although stress calculations have been provided by USS for the
condition of steady state temperature gradients, additional esti-
mates will be required of stresses associated with transient
conditions such as start up and shutdown. These estimates will be
required for the establishment of stress levels to be used in
fatigue testing of heater tube materials.
In view of the promising results of hydrogen permeation experi-
ments at NASA (which showed a significant reduction of hydrogenpermeation loss rates resulting from 2.5% CO and C02 additions to
the hydrogen), plans to discuss hydrogen barrier coatings for the
inside of tubes with Chemetal, Inc. were postponed until NASA data
are reviewed and the impact of C02 on the system is evaluated.
3.2.5.2 Cylinder Heads and Regenerator Housings
Metallographic studies of the engine-run heater quad rant conti-
nued. The heater head quadrant *as run at USS on the High
Temperature P-40 Engine for 7 hours at 7 MPa, 720° C; 83 hours at
15 MPa, 820°C and 752 hours at 7 MPa, 820° C (total accumulated
time 842 hours). The extent of porosity in the cylinder head andregenerator castings was examined at several critical locations.
Examination to determine the distribution of debris in the
regenerator, and additional metallography of the heater head
castings will be performed during the month of October. The
microstructure of the cast CRM-6D cylinder heads was examined and
was found to be qualitatively similar to that reported by Roy, et.
al. (A. Roy, F.A. Hagen, and J.M. Corwin, "Iron-Base Superalloys
for Turbine Engines", Journal of Metals, Vol. 17, #9, P.934,
[1965]).
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MTI has encountered difficulty in procuring precision castings of
cylinder heads and regenerator housings. Hitchiner Inc. has
refused to produce investment-cast cylinder heads and regenerator
housings. Howmet has been contacted regarding MTI's casting
requirements, but has not yet responded. Presently, both found-
ries are reluctant to devote large development resources without
clear identification of a potentially large market. MTI willpursue this procurement search with additional vendors. Meetings
were scheduled with Turbine Components Co. (Howmet, Mich.) to
discuss the precision investment casting of cylinder heads and
regenerator housings for a P-40 engine. MTI will also meet with
Cannon-Muskegon Foundry (Muskegon, Mich.), to explore their
processes of remelting.
MTI has received one hundred and twenty pounds of an experimental
iron-base casting alloy, XF-818, from Climax Molybdenum. Eighty
pounds has been sent to USS for the fabrication (casting) of
cylinder heads and regenerator housings. A portion was also kept
at MTI for mechanical testing and metallography. Testing of alloyXF-818 revealed that its structure was similar to that described
in a Climax Molybdenum Co. Research Lab Report. The alloy was
characterized by an interdendritic network of a eutectic struc-
ture, and presumably consists of borides, carbides and austenite.
A dispersed phase was also noted within the dendrites. The
phase's composition will be determined by additional testing.
A Material Task Force meeting was held on September 28th at MTI.
Participants from NASA and USS were present. Among the signifi-
cant items discussed were: work at NASA involving the reduction
of hydrogen permeation losses by the addition of CO and COo to the
hydrogen working fluid; MTI's work on heater tube requirements and
analysis, metallography on the engine-tested heater quadrant
received from USS, piston dome failure analysis, and plans for
component fabrication and testing; USS's method for repairing
heater tubes; and the possibility of having MTI's candidate heater
tube materials creep tested at Sandvik.
3.2.5.3 Piston Rod Surface Replication
Carbon film replicas were made from plastic film impressions of
the piston rod, which were taken during the teardown of the
engine. A technique was adopted for preparing carbon film replicas
for examination by electron microscopy, which will improve the
consistency of the results. MTI is now prepared to complete the
examination of piston rod wear patterns with the high degree of
resolution provided by transmission electron microscopy. This
method of piston rod surface examination will not only provide
quantitative information on the depth of microscopic features, but
will indicate the nature of surface topography and will improve
MTI's understanding of the mechanism of piston rod seal deteriora-
tion.
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3.3 MAJOR TASK 3 - BASELINE ENGINE SYSTEM (P-40)
The existing USS P-40 Stirling engine will be used as the baseline engine for
Stirling engine familiarization and as a test bed for component operating
conditions, component characteristics, and to define problems associated with
vehicle installation.
The baseline P-40 engines will be tested in dynamometer test cells as well as
in an automobile. Test facilities are being constructed at MTI to accomodate
this work.
3.3.1 Baseline Engine System (P-40)
USS will manufacture four P-40 engines, including spare parts. Engine/
dynamometer testing will include full and part power operation, tran-
sient and cyclic operation, start-stop cycles, and endurance testing.
Complete engine performance maps of fuel consumption, emissions, power,
and torque versus engine speed over the full range of engine operating
pressure levels will be obtained over the entire anticipated range of
operating heater head temperatures, conibustor flows, inlet temperatures,coolant temperatures, coolant flows, and coolant inlet temperatures.
Tests will be run with the complete Stirling engine system as designed
(with all auxiliaries installed and operating off engine power). Where
appropriate, selected auxiliaries and/or ducting may be simulated, or
compensated for. Tests will also be run with all auxiliaries removed
and their functions provided by test facilities, or compensated for.
AMG will modify an AMC vehicle for the P-40 engine, thereby gaining
experience and knowledge on the integration problems and requirements
associated with the installation of a Stirling engine in a passenger
car. Limited vehicle testing will be conducted by AMG to establishbaseline vehicle-affected engine perform ance, such as: fuel consump-
tion, emissions, and under-hood environment. The vehicle installation
and test is designed to familiarize AMG and other team members with a
Stirling engine-equipped vehicle and its performance and operation. It
will also establish baseline performance for the total program, inclu-
ding durability.
The P-40 is not an automotive designed engine and, consequently, will
primarily be useful for providing Stirling-powered vehicle integration
experience for AMG plus some limited data on vehicle performance in an
AMC passenger car.
3.3.1.1 P-40 Spirit
In the previous Quarterly Technical Progress Report, a summary was
presented of acceptance testing results for Stirling Engine No.
ASE40-8, the P-40 engine installed in the 1979AMC Spirit. Figure
3.3.1.1-1 shows the engine installed in the Spirit and Figure
3.3.1.1-2 shows the vehicle.
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As is to be expected in any new engine/vehicle system, numerous
problems were encountered and solved during the initial shake down
testing of the P-40 Spirit. The first half of July was devoted
by MTI to diagnosing these problems, correcting them by rebuilding
the engine, and verifying the corrections by power measurements on
a chassis dynamometer. The following problems were diagnosed and
corrected:
• The CapSeals
These seals were defective in all four cylinders. The
defect allows hydrogen to leak into the seal cartridges,
which in turn could cause an increase in dead volume,
out-of-phase return pressure, and partial short-circuit of
all four cylinders.
• Fuel Nozzle
The core of the atomizer nozzle was loose, which severely
resctricted the atomizing air flow.
• Combustion Air Throttle Valve
The air flow control valve was working erratically. Upon
disassembly it was found to be dirty. This imposed consi-
derable resistance to its movement, and caused the maximum
travel microswitch to lock in the full open position. This
condition results in an engine abort.
• Seals InGeneral
A cracked dome-to-piston 0-ring was found in at least onecylinder, and two cylinders had questionable piston seal
rings. There was a small hydrogen leak from the power
control valve to the atmosphere and a broken 0-ring in the
connection of the power control valve to the engine supply
line.
• Visual Inspection
. Over temperature indications were noted by rod discolora-
tion and deformed cap seals.
. One broken cap screw was found and another was locked in
place.
. Rust was noted on the cylinder walls.
. Dirt and material was found deposited on the underside of
pistons, in the piston grooves, and inside the seal
housings.
. A damaged/scored crank bearing was found in cylinder No. 3.
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The following major parts were replaced:
• The bearing bushing in the connecting rod from cylinder No.3.
• All four piston rods.
• Two pistons; cylinder No. 1 and No. 2.
• All piston seal rings.
• All eight maximum and minimum check valves.
• All four cap seals.
• All four main seals using a new design which requires no
scrapers or cylinder seal oil separators, and which has the
seal space connected to the minimum pressure manifold.
After the repairs at MTI, the vehicle made a round trip from
Albany, N.Y. to Lake George, N.Y., a distance of about 120 miles.
The vehicle was returned to AMG (in Detroit) on July 19, 1979, to
resume vehicle test activities.
Late in July, tests on various fans, fan shrouds, viscous clutches,
and drive ratios were performed at AMG. The optmum fan system
appears to be an 18.5" diameter "flex" fan, no viscous clutch, a
1.1:1 fan ratio and no fan shroud. During these tests, several
problems occurred which were corrected:
• Combustion air blower bearing failure;
• Loss of throttle control (loose electrical connection);
• Loss of ignition (broken thermocouple-actuated guard);
• Fuel nozzle atomizing air holes were blocked;
• Variator drive pulley bushing slipped , causing belt slippage
and low combustion air supply. (Caused by previous
repair/modification to pulley halves.)
While making repairs, it was decided to also nake the following
modifications, to see if vehicle performance could be improved:
• Install a loose 10.75" torque converter (1250 rpm stallspeed);
• Reduce the combustion blower drive ratio (two diameters of
pulleys were made for the blower, for trial purposes);
• Install a new, unmodified, varidrive pulley with the heavier
spring;
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• Incorporate an automatic fan electric clutch cutout, set at
18 mph;
• Install an 18.75" diameter flex fan with no viscous driv e
unit and a 1.2 drive ratio;
• Omit the fan shroud.
Between July 20 and August 24, 1979,AMG ran the Spirit in order
to collect the following operational and performance data:
• The speed relationship between the engine blower drive and
the vehicle crankshaft rpm was measured in order to initiate
effort to obtain a blower driv e with reduced power losses
and to optimize the variator drive system.
• The engine response time-delay was measured, at wide open
throttle (WOT), at frozen idle conditions, and at 50
atmospheres to 150 atmospheres of engine pressure. Cooling
tests were performed with v arious fan types to determine fan
rpm as a function of engine rpm, and fan performance as a
function of vehicle speed. These tests were aimed at
reducing fan power consumption.
• The adequacy of the cooling system was studied under idle
conditions. The cooling system tests scheduled in the Ethyl
Corporation Wind Tunnel will further d efine the adequacy of
the Spirit cooling system. Data were obtained with various
axle ratios and were compared to computer predictions of
vehicle simulation.
• Transmission torque converter comparisons were mad e with low
stall and high stall 10.75 in. units.
On August 24, 1979, piston rings were replaced because of poor
starting time. Rebuild was completed on August 26, and CVS
testing was started on August 27.
During Septe mber, testing and optimization continued and the
Spirit was readied for display at the October DOE Contractor
Coordination Meeting (CCM).
Engine operating time through September 30, 1979 was 139.5 hours,
and the Spirit odom eter read 1868 miles. The performance of theP-40 Spirit at the end of September is summarized in Table
3.3.1.1-1 along with a comparison to the P-40 Opel. These
performance figures are not final figures as the Spirit will
undergo additional optimization, modifications, and testing after
the October CCM.
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3.3.1.2 Mil's P-40 Engine
The pre-test documentation work at MTI on Engine No. ASE40-7 was
discontinued on June 29, 1979 in order to respond to the
investigation of the P-40/Spirit (discussed above). Effort was
resumed on July 26. 1979.
In August 1979, the documentation of ASE40-7 teardown was com-
pleted and the reassembly of the engine was started. Reassembly
was completed in September. After disassembly and inspection,
deposits/scale/rust was noted within the engine cooling system.
Surface rust and roughness were removed from the block's cylinder
walls by lapping with a micro-polishing compound. Several unsuc-
cessful attem pts were mad e to chemically remove the metallic
flaking material from the inside surface of the engine block. The
flaking was finally removed by sand blasting.
The original heater head was reinstalled and leak checked with
helium gas at 1000 psig. The helium charge decayed 27.5% in 30minutes, as shown below.
Charge Pressure Time
(psig) Hrs;Min
1000 13:29
920 13:34
900 ' 13:35
725 14:00
This leakage rate was unacceptable for operation. Two heater
tubes, Nos. 9 and 16 in quadrant No. 1, each had a mid-span
section removed and replaced with a new section prior to shipping
from USS. The new tube sections were attached to the existing
structure with furnace brazed sleeves. The leakage occurred at
the inboard sleeve of each tube. A repair replacement heater head
assembly has been shipped from USS for delivery to MTI early in
October.
3.3.2 Facilities
The test facilities and equipm ent necessary to completely evaluate
engines and components will be designed, built and procured at MTI. It
is anticipated that this will include installation at MTI of two engine
test cells with appropriate data acquisition equipment and component
test cells to be used for component development purposes.
The component test facilities will include heater system test rigs to
evaluate heater heads under simulated engine conditions. A cold flow
test rig will support this effort. A combustion facility will be
installed to evaluate new combustion system designs, and a fuel nozzle
test stand is also envisioned. A subsystem test facility will allow
coupling of the heater head/combustor/preheater in order to verify and
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test the entire subsystem. The heater system facility will be supported
by a high speed data acquisition system and an automotive exhaust
emission sampling and analyzing system.
Facilities, apparatus, and rigs will be constructed to investigate and
develop piston-rod sealing, the hydrogen compressor system, the
combustion blower, power control check valves, and the power control and
air/fuel control systems. In order to start engine testing before
completion of the primary (Phase I) facility, MTI is setting up a
portable, skid-mounted "Work-Around Facility".
Procurement of the Work-Around Facility is complete ex cept for the fuel
flow met er, which is due in October. The Work-Around Facility consists
of portable skid-mounted equipm ent containing engine cooling facilities,
dynamometer cooling, engine mounting and brake assemblies, fuel/air
supply, and the operator control equipment. These five skids are shown
in Figures 3.3.2-1 through 3.3.2-5.
All five skids were placed in their final locations and interconnected.
The three outside skids: No. 1 (Engine Cooling), No. 2 (DynamometerCooling) and No. 4 (Fuel) were covered with weather enclosures. Skid
No. 5 (Operator Control) has been hooked up to the Phase 1 facility
electric power supply. Skid assembly work is complete except for the
fuel flow meter installation and the ASE40-7 engine mounting and
hook-up.
All construction is complete for the Primary (Phase 1) Facility at MTI
except for the volt age regulators for clean-power, which are expected to
be delivered in October. The heat pumps for the control rooms and
passageways were tested, balanced , and are now operational. Prepara-
tions have begun for testing the other subcontractor installed systems.
The General Electric edd y current dynamometer was installed in theengine cell. The dynamometer cooling water tank was also installed.
Assembly of the 2,000 gallon water tank, with its associated pump skid,
was completed in the utility house. Plumbing of the water cooling
system continued as purchased hardware was received.
The programmable control cabinet, to be used for routine sequencing
functions, is 50% complete. Ad dition of the controller mainframe will
complete this assembly.
Planning for the software system generation has begun. This planning
requires hardware configuration information (which is available) and
software d ocumentation (some of which is supplied with the computersystem). Guidelines are being generated for long and short term system
operation. These guidelines will be used to design useful software
support modules for the system. Signal interconnection drawings were
prepared to aid in identifying system signals.
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Figure 3.3.2-1 Skid #1 — Engine Cooling
Figure 3.3.2-2 Skid #2 — Dyno Cooling
MECHANICAL
TECHNOLOGY
INCORPORATED -72-
MTI-19
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Figure 3.3.2-3 Skid #3 — Engine/BrakeAssembly
Figure 3.3.2-4 Skid #4 — Fuel/Air
MECHANICAL
TEC H NOLOGY
INCORPORATED -13-M T I- 1 9 2 7 9
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Figure 3.3.2-5 Sk id #5 — Operator Control Assembly
MECHANICALTEC H NOLOGY
INCORPORATEDS
HTI-19331
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3.4 MAJOR TASK 4 - ASE MOD I SYSTEM
A first generation Stirling engine system will be designed, fabricated and
developed.
Engine/dynamometer testing will include full and part power operation,
transient and cyclic operation, start-stop cycles, and endurance testing.
Com plete engine performance maps of fuel consumption, emissions, pow er, andtorque, versus engine speed over the full range of engine operating pressure
levels, will be obtained over the entire anticipated range of operating heater
head tem peratures, combustor flow, inlet temperatures, coolant temperatures,
coolant flows, and coolant inlet temperatures.
Tests will be run with the complete Stirling engine system as designed (with
all auxiliaries installed and operating off engine power). Where appropriate,
selected auxiliaries and/or ducting may be simulated, or compensated for.
Tests will also be run with all auxiliaries removed and their functions
provid ed by test facilities, or compensated for. One or more engines will be
installed in a vehicle(s).
3.4.1 Heat Generating System
The heat generating system w as studied with respect to a conventional
system with EGR, and a system using CGR. The system studies have
resulted in the choice of the CGR system in preference to the EGR
system.
The combustion system was studied with respect to the by-pass v alve on
the top of the combustor. Sketches were made of two different
combustion chambers w ith diff erent heights (120 mm, 150 mm) for use in
the ASE Mod 1 to be installed in the Spirit. From the design point of
view, the 150 mm combust ion chamber is preferred, however, some redesignof the vehicle hood will be required. The conbustor is shown in Figure
3.4.1-1.
3.4.2 Preheater
A preliminary design was made of the preheater matrix (CGR system). The
number of preheater plates will be 1,200 and the plate material thickness
will be 0.15 mm. Layouts were made for two diff erent heights of the
matrices after considering combustion chamber heights. The design
allows the preheater matrix to be removed for cleaning without having to
remove the preheater housing from the engine. Tests are being performed
to braze the complete matrix. If the tests are not successful, the
brazing system used in the previous P-40 preheaters will be applied.
Air passages were tested in the USS Fluid Analysis Laboratory to
establish the flow dist ribution of the preheater housing. Effort was
also directed to the form of the insulation material for the by-pass
function of the preheated air. Presently, two different preliminary
layouts are under investigation for the total external heating system.
The air passages may be manufactured from aluminum castings, and the top
cover may be manufactured from pressed aluminum sheet or aluminum
castings.
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3.4.3 Heater Head
The heater head was studied with respect to the location of the heater
tubes in the manifold s and the vertical location of the tubes. The
heater head will be bolted with M12 (a 12mm bolt with a metric thread)
bolts. Preliminary analyses indicate the following thickness of the
housings:
Thickness Thickness
at Top (mm) Above Flange (mm)
Cylinder housing 7 4
Regenerator housing 12 5.5
The bolt arrangement will be fatigue tested while connected to the
water jacket and the duct plate.
The dimensions, form, and appearance of the air passages in the upper
part of the cylinder and regenerator housings were established. The
cylinder and regenerator center lines were moved 1 mm and 2 m m,
respectively, from the engine center line. Different procedures for
joining the manifolds to the cylinders and regenerator housings are
under investigation. The alternatives are electron beam welding and
brazing. Coordinates were established which define the geometry of the
heater tubes, and bending tools for the tubes were manufactured.
Asymmetric finite element models were set up for stress analysis of the
heater head. Different designs will be analyzed for stress
concentrations. Different cases of loading were consid ered, such as
temperature load (T), internal pressure (P), and combinations of
temperature and pressure. The results are shown in Figures 3.4.3-1,
3.4.3-2 and 3.4.3-3.
3.4.4 Gas Cooler
Gas cooler tube lengths were increased by 5 mm and a preliminary design
was made. The new design allows the 0-ring to be mounted radially. It
will ensure that the 0-ring is retained in the groove in the block while
dismantling the cooler. Two of the tested aluminum gas coolers have
fatigue cracks in the dimpled section of the tubes. New thermal
calculations will be performed with less dimpled tubes, which probably
will result in a different number of tubes per cooler unit. A redesignof the aluminum gas coolers is underway by the manufacturer and a
revised test plan is being prepared.
3.4.5 Regenerators
The regenerators' filling factor was reduced from the present 43% to
40-41%.
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Loadcase I : Temperature Load T
Loadcase III : Pressure Load Pmean value
Loadcase V : T + P .
Loadcase VI : T + Pmean
Loadcase VII : T + Pmax
Figure 3.4.3-1 MOD I Regenerator House — Effective Stress in N/mm2
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Loadcase III : Mean Pressure P
Loadcase V : T + PminLoadcase VI : T + P
Loadcase VII : T + Pmax
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Key
Loadcase I : Temperature T
Loadcase III : Mean Pressure P
Loadcase V : T + P ,mm
Loadcase VI : T + P
Loadcase VII : T + Pmax
Figure 3.4.3-3 MOD I Cylinder House — Effective Stress in N/mm2
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3.4.6 Cylinder Block
A duct plate proto type for strength testing was manufactured and
statically pressurized for deflection measurements. Strain gauge
measurements indicate a maximum stress of about 160 MPa. A redesign was
started in order to diminish the displacements and a fatigue test is
plannedfor the new
design.In
this test,the
duct plate willbefastened to the one-fourth water jacket.
The cold connecting duct for the cylinder block strength test (cold
engine system) was been statically pressurized for deflection measure-
ment. The central deflection was about 70 y m at a pressure of 20 MPA,
which is acceptable from the functional point of view. However, the
largest deflection at the position of the 0-ring was 34 u m. Such a
deflection is considered excessive and a revised design of the cold
connecting duct plate was manufactured and statically pressurized for
deflection measurements. The central deflection was approximately 40 Wm
at a pressure of 20 MPa. The deflection at the position of the 0-ring
was 21 pm. The new duct plate is approximately 60% stiffer than the
initial d uct plate. Aft er the deflection measurement was performed, the
duct plate was bolted to a section of the water box and sent to the
National Swedish Testing Authority for fatigue testing. Sketches of the
initial and revised duct plate are shown in Figure 3.4.6-1.
Due to the design, the cooling water circuit of the cylinder block is
practically perfect with respect to flow distribution through the two,
almost identical, parallel paths. A later flow test will quantif y total
flow resistance in the system in order to specify pump capacity. Two
pump speed options were built into the drive transmission.
3.4.7 Seals
The duct plate in the cylinder block was mod ified due to initial static
tests. A new sample for fatigue tests has also been cast. Further
minor modifications will be made to match adjacent parts (mainly the
0-rings) and to integrate it with the cylinder liners. The main seal
system d esign was finished.
j.4.8 Cooling System Development
The Cooling System Task Force met in Sweden in September, and they
visited several Swedish automobile radiator manufacturers: Granger
Radiator Division of Svenska Metallverken (Finspang, Sweden) and
Blackstone (Solvesborg, Sweden).
Granges Metallverken is the world's largest prod ucer of copper strip
used for the fabrication of radiator fins (automotive type construc-
tion). They also design and dev elop automated equipment for radiator
fin fabrication. Presently, Granges is competing for some Ford business
and a specific Ford production radiator is targeted. This radiator has
a single row of fins, which results in a lighter design and a more
efficient use of the copper. It is the opinion of the Task Force that a
minimum of two Granges radiators should be evaluated as possible
candid ates for the Mod I cooling system.
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Initial Duct Plate
Revised Duct Plate
Figure 3.4.6-1 Initial and Revised Duct Plate
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Blackstone (Sweden), a licensee of Blackstone USA, produces radiators
for Volvo on a highly autom ated production line. On a lower production
basis, truck and off-highway equipment radiators are produced. They are
also engaged in a limited production activity for aluminum truck
radiators. Blackstone has no prod uct development activity and ,
therefore, is not a potential source for high heat transfer cores.
However, they have a test facility for characterizing radiators and haveagreed to perform tests for us on competit ive equipment. They can
accom mod ate two radiators per day. Radiator characterization data will
also be supplied to USS for computer code refinement.
AMG and MTI attended three major meetings:
• Task Force Meeting (Malmo, Sweden).
• Granges Radiator Division, Svenska Metallverken (Finspang,
Sweden) to review a high heat transfer radiator core.
• Blackstone (Solvesborg, Sweden) for a tour of theirfacilities.
As the result of these meetings, it was agreed that the core offered by
Granges is a viable candid ate for the ASE Mod I cooling system, and that
Blackstone facilities will probably be employed for characterization
curves of candidate cores.
The P-40 mock-up will be installed in the Concord Cooling System Test
Rig Vehicle and air mass flow measurements will be recorded. These
measurements will be across the radiator core at various air speeds and
ambient temperatures. A redesign effort on the front of the Concord
will also start. The objective of this effort is to increase the core
frontal area of the radiator and also increase its unobstructed frontal
area for impact air. An air scoop and dams will be considered.
3.4.9 Piston/Piston Rod Assembly
The type and d imensions of the sliding seal system were determined.
Adjustments will be mad e after further testing. The type of crosshead,
piston/piston rod attachment for the piston rod assembly, and their
dimensions, were d eterm ined. More analysis is needed for the static gas
seals and the piston ring function. These possible revisions might add
some length to the overall engine height. In order to reduce total
engine height, a relatively large cone was made in the lower end of the
piston. The design of the piston is still in progress, and the design
of the piston dome was finished. The piston rod design was finished and
an integral crosshead was chosen.
The gap between the dome and the cylinder was tested and a report is
being prepared. Testing indicated that an increased gap detrimentally
affected the engine power and efficiency as well as the 0-ring seal, due
to high temperatures in the lower region of the cylinder wall.
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3.4.10 Engine Drive System
The design of the engine drive system was evaluated at a meeting with
Ricardo. Two sets of different gears will be supplied by USS for drive
system No. 1 and 2.
The engine drive system was redesigned to comply with the cylinder and
regenerator housing changes. The design of the bed plate will remain
unchanged. Some minor mod ifications are still incomplete, for instance:
the interface between the bed plate and the cylinder block, the
placement of the oil stick, etc. The external profile of the oil sump
will be defined at a later date with respect to the installation in the
vehicle.
A contract supplement was made with Ricardo, which includes the design
and manufacture of a test rig for the flywheel, starter adap ter, engine
mounting brackets, and clutch arrangement. Delivery of the first drive
unit is expected by June 1,1980.
3.4.11 Air/Fuel System
The burner for the air/fuel system has been mod ified. Mock-up parts
were ordered and full scale installation drawings have begun.
3.4.12 Auxiliaries
The layout of the auxiliaries was studied in detail and are being
modified according to the new design of the components, such as the
preheater and the cylinder block.
3.A.13 Flow Distribution Tests
The design of the test objects was completed. Testing in the Fluid
Dynamic Laboratory was begun in October. Figure 3.4.13-1 shows the air
preheater flow distribution test rig and Figure 3.4.13-2 is a photograph
of the rig.
3.4.14 Joining Techniques
Brazing techniques and electro beam welding techniques will be tested on
regenerator housings. Manufacture of cylinder housings were delayed and
parts are expected to be delivered in October. These joining techniqueswill form the basis for the manufacture of test pieces for endurance
testing. Testing is due to start in October.
Brazing tests will be performed on a complete heater matrix using 0.3 mm
plates instead of the planned 0.4 inn plates. Figures 3.4.14-1 and
3.4.14-2 show the test brazing equipment.
3.4.15 Power Control
The check valve test rig has been operating for a total of 2010 hours.
Tests with the Bauer KB 057909-080 check valve were terminated after
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a;
C OI00
C fl
idu
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Figure 3.4.13-2 Air Preheater F low Distribution Test Rig
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Figure 3.4.14-1 Fixture fo r Brazing the Preheater Matrix
3 0 7 7 1
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Xk _
4-
re
k _0)•03(L )
JZ0)
o
l/l0)
O J Dc
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(N
rn
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operating for 600 hours; the valve functioned well and no valve failure
occurred.
A standard, "off the shelf", SKF-manufactured electrical actuator was
procured. The actuator has the correct force but the response is too
slow. USS is waiting for a reply from SKF on their request to develop aunit with a faster response. The actuator will be used for developing
the control circuitry and for driving the test units of the spool
valve.
MTI and USS personnel visited Valcor, Inc. The problems involved with
solenoid valve operation in the Stirling engine control system were
thoroughly discussed . Valcor showed a positive interest to engage in
development work on solenoid valves for the Stirling engine control
system.
All parts of the hydraulic test rig were delivered and the rig is now
being assembled.
3.4.16 Air Blower
A complete combustion air blower was tested for noise level, capacity,
and efficiency. Figure 3.4.16-1 is a performance map of the belt driven
Flaff blower and Figure 3.4-16-2 is the performance map of the gear
driven Sunflo blower. The differences in efficiency and capacity depend
on the measuring eq uipment used, but it is felt that the results were
satisfactory. The blower has operated for approximately 25 hours with no
problems. A noise level test was made with four different flat belts.
Endurance testing and cold start testing will be performed later.
Figure3.4.16-3
is a phot ograph of the combustion air blower variator,and Figure 3.4.16-4 shows the results of the noise test.
3.4.17 Atomizer Air Compressor
The test with a modified compressor revealed that the layer of Teflon on
the end plates was not enough to avoid failure. A misalignment between
the shaft and the compressor housing was discovered and corrected , but
did not solve the problem. A number of possible solutions will be
tested to try to solve the problem. Figure 3.4.17-1 shows the atomizer
air compressor with the servo oil pump.
3.4.18 Stirling Engine System
Computer predictions were made for the preliminary version of ASE Mod I.
The dimensions are shown in Table 3.4.18-1. Table 3.4.18-2 shows the
preliminary, calculated ASE Mod I values for indicated power and
efficiency. The preliminary computer predicted dimensions, are being
continuously upd ated . Minor revisions are expected to take place before
a final version will be established.
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Figure 3.4.16-1 Performance Map of the Flaff Blower
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Figure 3.4.16-2 Perform ance Map of the Sunflo Blower
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Figure 3.4.16-3 Co m bustion Air Blower Variator
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' ' _ C o _ # * P H _ S _ £ J O * at/* A.
r'-''-'irr ^ ^ar -_29O5_22. ^7_
___.
K"-..":-
=?=F -J^
Figure 3.4.16-4 Results of Combustion Air Blower Noise Tests
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Figure 3.4.17-1 Atomizer Air Compressor with Servo Oil Pump
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Drive Mechanism and Cylinder!
Piston diameter
Piston rod dlaaeter
Displacer d o m e height
Cap dlsplacer dome-cylinder vail
Crank radius
StrokeConnecting rod length
Swept voluae
Regenerator (Cauxe type)
Units per cycleD l ameter
Top cross section area
Length
Wire diameter
Filling factorWeight per engine
Cooler
Units per cycle
Tubes per cycle
Inside tube diameter
Outside tube diameter
Length of one tube
Effective length of one tube
Heater
Tubes per cycle
Inside tube diameterOutside tube diameter
Length of one tubeEffective length of one tube
Heat flux at full load, inner surface
68
15
120
0.417
34
95
123.5
180
50.27
SO
0.0543
3.5
1451
1
2
87
75
24
34.5
270 .
243
78
anm aon
m aaa
m a
m a
ca3
mcm
3
ran
m m
I
kg
m m
mm
mm
HU B
m am am mm a
W/cn .2
Connecting Duct Cylinder
Cooler
Volume 40 cm3
Cross section area (narrowest passage) 4. 57 cm2
Regenerator
Volume 2.5 cm3
Length 0.5 na
Heater
Volume 24 cm3
Cylinder - Connecting Duct Heater
Volume 11.5 cm3
Cylinder
Clearance volume exp. space 3.6 cm3
Clearance volume comp. space 3.4 cm3
Table 3.4.18-1 Preliminary ASEMOD I Dimensions
HKCHAMCAL
TECHNOiOOT
INCORPOH»T£D
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Ind pe—r («)
411 POVI •
111 POVI >
411POVI -
4)1 POVEI •
4)1 P O U E I •
411P4VI •
411P9VEI "
4)1 POVEI -
4)1PBVfl -
411 P
4)2 P O K E ) •
432 POVEI •
432 POVEI -
1)1 POVEI *
4)1 POVCI •
4)1 POVI -
1)2 P9VEI -
412 POVEI •
43 7 Povra •
4)2 POVII •
412 POVEI •
1)2 POi/'l -
4)2 POVEI •
•4)2 POVEI •
132 POUEI •
432 POVEI "
412 POVEI -
412 POVEI -
412 POVEI •
1)2 POVII •
4)2 POVfl .
412 POVEI -
411POVCI -
41POVEI •
412 POVEI •
431 POVEI -
4)2 POVEI •
432 POVEI •
432 POVEI •
432 POVl •
1)2 P O W E I •
431 POVI •
412 POVI •
4)2 POVCI •
411PIVEI •
411POVEI •
41POVI •
1.1074*01
6.1431*0)
..0*44*03
7.72*1>0>
»1147*01
1.0224*04
1.1025*04
11411*04
4.37*1*03
14711*01
1.22*7*0*
1.5717*04
1.1*11*04
2.1417*04
2.1*33*04
2.3245*04
*4713*03
1.2315*04
1.1217*04
2.3474*04
2.3713*04
).2)41*04
3.5754*04
1.1347*04
1.3141*0)
1.4414*04
2.4010*04
).100**04
).7)25*04
4.2140*04
4.74)7*04
5.0*50*04
1.0301*04
2.0)31*04
7. •.34.04
3.1151*04
4..1»3>04
5 1013*04
5.54*3.04
t.1047*04
1.7444*04
1.3212*04
4.5517*04
5.4*40*04
«.2450*04
4.*511*0<
7.4424*04
Moff ci«"CT Newp
452 (Tt
452 IT
152 ETI
452 (1*
451 Ell
451 (T
451 ETI
452 CTI
452 (Tl
45 2 CT t
432 ETI
432 lit
432 ETI
152 CTt
452 ITI
451 (Tl
452 CT I
452 IT!
452 CTI
452 ITI
452 (Tl
452 (Tl
452 CT I
452 (T
452 (Tl
452 ETI
452 ETI
452 ETI
432 ET I
132 ETI
437 ETI
452 ETI
432 (Tl
432 (Tl
451 (Tl
451 (Tl
451 (Tl
451 CTI
451 CTI
451 CTI
451 CTI
151 CTI
151 CTI
431 (Tl
451 CTI
431 CTI
451 CTI
- 2. 004-01
. 3).7137-01
• 4.0)74-01
• 4.15*1-01
• 4.1441-01
• 4.0*11-01
• .«4?*-01
• 1.7775-01
• 1.1115-01
• *.441*-01
- 4.4414-01
• 4.*04*-01
• 4.4512-01
- 4.5411-01
• 4.4212-01
• 4.2542-01
• 4.2420-01
- 4.7251-01
• 4.1174-01
• 41473-01
.47IM01
• 4.1701-01
• 4.5)41-01
• 4.13*2-01
• 1.4077-01
• 4.*.454-ni
• 4.*35»-01
• 4. '060-01
» 4.1224-01
• 4.7013-01
• 4.55)4-01
• 4)7)»-01
• 4.04)1-01
• 4.441*-0!
• 4,»73)-01
» 4.*2)*-01
- 4.I27*-01
• 4.4*73-01
- 4.5407-01
• 4.3541-01
• 4.7477-01
• 4.««03-01
• 4.V17I-01
• 4.1157-01
- 4.47*1-01
• 4.31)1-01
- 1114101
217 Pn
117 •••
117 Pn
117 PI*
117 pin
117 PIP
117 POP
117 Pn
117 Pn
117 PIP
217 PI»
217 PIP
217 pin
217 Pn
217 PIK
117 PI"
217 pin
217 PIP
217 Pn
217 Pn
217 PIP.
217 p«n
717 pin
217 pin
117 pin
217 pin
217 Pn
217 Pn
217 Fn'
117 pin
. 217 Pn
117 FR
117 pin
117 PI*
117 pin
217 Pn
117 PIR
• 217 PI*
217 Fn
117 Pn
117 p«n
117 PIP
117 F»n
117 Pin
117 Fin
117 Fin
117 Fin
rvMr* IP*)
- 1.5000*0*
• I.500O*0*
• t.5MO*0*
• 1.5000*0*
• 2.5000-06
* 1.5000*04
• 1.5000*0*
- 1.5040*0*
- 5.0C00.04
• 5.0000*0*
• 1.0000*0*
• 3.0000*0*
• 3.0040*0*
• 3.0040*0*
> 5.0000*0*
• 3.0000*0*
• 7.5000*0*
• 7.5000*0*
• 7.5000*0*
• 7.3000*0*
• 7.5000*0*
• 7.5000*0*
• 75000*04
• 7.3000*04
• 1.0000*07
• 1.0000*07
• 1.0000*07
• 1.0000*07
* 1.0000*07
• 10000*07
• 1.0000*07
• 1.0000*07
• 1.25CO*07
• 1.2500*07
• 1.1300*07
• 11300*07
• 1.2500*07
• 1.7500*07
- 113CO*07
> 1.J5CO-0?
- 1.3000*07
* 1.3000*07
• 1.5000*07
> 1.5000*07
• . ).5000*07
• 1.5000*07
• 15000*07
- 1.3000*07
HMV
H IIV
HICV
111 111
111 ICV
211 OEV
HIEV
HIEV
111 IEV
211 I(V
211 ICV
IIIIIV
211 IEV
211 IEV
211 IEV
211 MY
211 ICV
211 IEV
211 ICV
HI IEY
211 IEV
HIEV
111If*
111 IEV
HMY
HIEV
211 IEV
211 IEV
211 KV
HICV
IIIKV
111 ICV
211 IEV
H KV
111KV
H KV
H KV
111 1C*
H 1C*
H1C*
111 KV
H ICV
H KV
H KV
H 1C*
H KV
H 1C*
H KV
n-
• 1.0000*01
• l .OCOC-03
• 1.3000*03
• 1.004C*0)
> 2.3000*03
• 3.001C-03
• 1.5000*0)
• 4.000C*0)
* 3.0000-02
• 1.0000*0)
> 1.1000*0)
• z . c e o o - 0 3
' 1.300C*03
• 3.0040*0)
• 3.5000*0)
• 4.0COC-01
> 3.0000*02
• 1.0000*01
• 1.3000*0)
• 1.0040*0)
- i.3eoe*o)
> 3.0000-03
• ).3000*03
• 4.0000*0)
• 5.0000*01
• l .OCOC-03
- 1.5000*0)
» 2.0000*0)
• 2.5000*03
• ).0000*03
- 3.5000-03
• 4.BOOO-03
• 3.0COO*07
• 1.0000-0!
'13000-01
• 2.COOO-01
• 11000*01
• 3.0100-0!
• 1.3000*0)
• *.«onc*oi
• 3.0000*02
* 1.0000-0]
• 1.3000*0)
- 1.0000*0)
• 1.5COO*03
• I.OCOO-OI
• 3.3000*0)
• 4.0001*03
Table 3.4.18-2 Preliminary Calculated MOD I Values for Power and Efficiency
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Table 3.4.18-3 contains the calculated net power (in Watts) and the net
efficiencies as a function of mean pressure and rotational speed. The
calculations used hydrogen as the working gas,a heater tube temperature
of 720°C, and cooling water temperature of 50°C. The friction and
auxiliary power requirement used to perform the net power calculations
are shown in Table 3.4.18-4 at two operating points: full load,
P = 15 MPa,and 4000 rpm; and part load, P = 5 MPa,and 2000 rpm. The
radiator fan power was not included in this calculation.
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*L po.«r (V)
Il
111
(4.0 rtrr • ?.*:|3t*0<
44 > f . f f - 3.?20«*D(
Tab le 3.4.18-3 Ca lculate d Net Power and Net Efficiencies of the MOD I Engine as a Function o
Mean Pressure andRotational
Speed
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FULL LOAD
INDICATED POWER
FRICTION
AUXILIARIES
NET POWER
EXT, HEATING EFFICIENCY
NET EFFICIENCY 29.1 I
PART LOAD
INDICATED POWER
FRICTION
AUXILIARIES
NE T P01VER
EXT. HEATING EFFICIENCY
NET EFFICIENCY 29.1 \
Table 3.4.18-4 Friction and Auxiliary Power Requirements Used to Perform Net Power Calculati
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3.5 MAJOR TASK 5 - ASE MOD II SYSTEM
The second generation engine will be designed, fabricated and tested as an
"experimental" engine system. It will be power rated according to the
reference engine system studies, using the first generation engine system as
the basis for improvement. The prime objective will be to upgrade the first
generation engine system to improve efficiency, and to improve durability and
reliability.
Only high confidence level component and subsystem developments will be used.
The design will reflect the use of automotive engineering design and
fabrication techniques to the max imum extent possible. Emphasis will be on
performance and durability/reliability.
Engine/dynamometer testing will include full and part power operation,
transient and cyclic operation, start-stop cycles, and endurance testing.
Complete engine performance maps of fuel consumption, emissions, power, and
torque, versus engine speed over the full range of engine operating pressure
levels, will be obtained over the entire anticipated range of operation,
heater head temperatures, combustor flows, inlet temperatures, coolanttemperatures, coolant flows, and coolant inlet.
Tests will be run with the complete Stirling engine system as designed, with
all auxiliaries installed and operating off engine power. Where appropriate,
selected auxiliaries and/or ducting may be simulated, or compensated for.
Tests will also be run with all auxiliaries removed and their functions
provided by test facilities, or compensated for.
Automobile/engine testing will be performed in order to establish
engine/vehicle interaction and engine-related driveability, fuel economy,
noise, emissions, and durability/d riveability.
3.5.1 Endurance Test on P-40 Engine (ASE40-4)
At the end of the last quarter (as stated in the previous Quarterly
Technical Progress Report), after 1093 hours of testing at 820°C, the
engine ex perienced a heater tube failure in the third quadrant. The
failed tube was replaced and engine testing was resumed in early August.
After nine hours of operation, the engine was stopped due to hydrogen
leakage in the heater. The leak was located at the manifold on cylinder
No. 3 and at the brazed joint between the tubes and the manifolds.
Figures 3.5.1-1 and 3.5.1-2 show the failure (crack). After the engine
was again repaired, testing resumed. An hour and a half later, a new
leak developed at the same location, and testing was again stopped. TheP-40 endurance engine is shown in Figure 3.5.1-3.
A new Multim et N-155 heater, which contains a metallic flame shield made
of Kanthal (a special high temperature material), and a new preheater,
were fitted to the endurance test engine. After running the engine for
approximately 33 hours, a cyclic high temperature test was initiated on
the Multimet N-155 heater head. After approximately 63 hours of
operation, two bolts in the regenerator housing failed. The bolt
failure is under investigation.
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cro
-DO J
_*urei_U
tn
ro
S!D00
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Q J
•5DO
ECu
c
c
o
LO
"oM—
"E
2-ov
u
u>-(—
o4->
cc u
EO J00
JSc
I
iri
< U
00
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Fig ure 3.5.1-3 P-40 End uran ce Test Engine
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The total operating time of the endurance engine reached 1200 hours.
3.5.2 Annular Regenerator
Design work for the annual regenerator for the endurance engine
(ASE40-4) is completed and manufacturing of parts has begun. The
assembly of the engine is in progress. Figure 3.5.2-1 shows the annularregenerators which surround each cylinder. The heater for the annular
regenerator concept is shown in Figure 3.5.2-2 and Figure 3.5.2-3. The
bottom of a heater quadrant is shown in Figure 3.5.2-4. Figure 3.5.2-5
shows the engine mounted on the test rig. The regenerators and coolers
are not yet available.
The annular regenerator concept provides identifiable benefits relative
to the external regenerator design currently utilized in the existing
engines. This design, as its name implies, wraps the regenerator, in
annular fashion, around the cylinder head instead of placing this
component in a separate chamber outside the block outline of the
cylinders. Figure 3.5.2-6 illustrates this concept and compares it to
regenerators in the P-49 engine. This provides the potential for both a
decrease in engine size and weight due to reduction of the engine
envelope. The envelope reduction allows the heater head to decrease in
size, since the discharge side into the regenerator can be reduced in
diameter. This in turn provides the potential for reducing the diameter
of the combustion chamber/preheater components.
3.5.3 Seal Development Test Rig No. 1
After the Seal Development Test Rig No. 1 ran for 226 hours, the gas
compressor wrist pin bearings wore out and were replaced. Oil was found
on the top side of the diaphragms which are shown in the diaphragm seal
drawing, Figure 3.5.3-1. An excess amount of oil was also found in the
Deltech 115E filter, which indicated that the oil-drain capacity of the
seal system was too small. The drainage capacity was improved by
drilling bigger drain holes and by minor plumbing changes. The whole
test rig was then cleaned and the filter was replaced. In spite of the
problems with the test rig itself, no diaphragms have ruptured due to
fatigue. Figures 3.5.3-2 shows two views of the test rig.
The compressor check valve spring had to be replaced twice, and the
Vespel back-up ring in the compressor piston ring set was also replaced.
The compressor piston ring failure was probably due to foreign particles
emanating from pieces of a broken check valve spring. Excessive gas
leakage was noted for a period of time. The sliding rod seal was
replaced, but the leakage rate continued to be excessively high.
Further investigation showed a leak in the plumbing, which was then
repaired. Total test rig accumulated running time reached 441 hours on
September 30th.
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Figu re 3.5.2-1 P-40 with Annular Regenerator-Type Heater — Regenerators Shown
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Figure 3.5.2-2 P-40with Annular Regenerator-Type Heater, One Quadrant Removed
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Figure 3.5.2-3 Close-up View of Annular Regenerator-Type Heater Mounted
on the P-40 Engine
MECHANICAL
TECHNOLOGY
INCORPORATED
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Figure 3.5.2-4 Annular Regenerator-Type Heater, Underside View of Quadrant
MECHANICAL
TEC H NOLOGY
INCORPORATED-110-
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Figure 3.5.2-5 Annular Regenerator-Type Heater and P-40 Engine Mounted on Test Skid
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Endurance Engine
Figure 3.5.2-6 Cross Section of Annular Regenerator in the Endurance Engine (ASE-40-4) asCompared to Cross Section of Regenerator in a P-40 Engine
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Piston
Kapseal
Rod
Rubber Diaphragm
Oil Scraper
Hydrogen Seal
7 9 2 7 5 7
F i g u r e 3.5.3-1 Dia ph r a g m Seal Concept
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Figure 3.5.3-2 Diaphragm Seal Test Rig
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3.6 MAJOR TASK 6 - PROTOTYPE ASE SYSTEM STUDY
This task will commence in the 1982-83 time period, and will consist of
studies concerned with bringing the ASE from its expected state of development
in September, 1984, to the start of production engineering.
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3.8 MAJOR TASK 8 - TECHNICAL ASSISTANCE
Technical assistance to the Government, as requested, will be provided
pursuant to the Technical Direction Clause of the contract. This effort will
include: Stirling engine and/or vehicle systems for DOE/NASA demonstration
purposes; models and displays for use at Government and professional society
technical meetings; computer program assistance to evaluate various NASAspecified engine modifications, parametric engine variations and engine
operating modes; training of personnel in the operation, assembly and
maintenance of Stirling engine systems and vehicles delivered to NASA;
appropriate communication media including brochures, audio-visual materials,
other literature, etc.
MTI has ordered and received a permanent display unit for use at technical
meetings and expositions. Plans are currently underway to use this display
for the October CCM in Dearborn, Michigan. The theme of this meeting will be
"Component Development". The P-40 Spirit and P-40 Opel will be on display and
available for demonstration rides. Technical papers will be presented by
MTI, USS, AMG and Ricardo.
Other effort under this task included:
• Photography, display materials and brochures for handout at the October
CCM.
• Repair of minor electronic damage to the P-40 Opel caused by a wiring
short circuit which occurred on September 18th.
• Renting a booth for the SAE mppfing in February 1980 in Detroit.
• Providing DOE with a versatile and portable display for use in theWashington, D.C. area.
• Design of an interlock system for the hood of the P-40 Opel and P-40
Spirit, and order of all hardware.
• Technical support to NASA for the disassembly and reassembly of the NASA
P-40 engine (ASE40-1).
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3.9 MAJOR TASK 9 - PROGRAM MANAGEMENT
This task defines the total program control, administration and management,
including reports, schedules, financial activities, test plans, meetings,
reviews, seminars, training, and technology transfer.
Task elements include:
• Program management.
• Technical direction.
• Monitoring of technical and financial progress.
• Report preparation, publication and distribution.
• Preparation of test plans, work plans, design reviews, etc.
• Coordination of monthly m eetings, review meetings, etc.
• Transfer of technology to the United States.
• Training of personnel.
• Seminars and technical society presentations.
• Government meeting coordinations and presentations.
• Engineering drawings and installation, operation and maintenance
manuals.
• Product assurance.
• Other items related to overall program management and control.
Effort continued at MTI on the cost proposal and work plan for the modified
program. Several meetings were held with NASA to further define the program
against projected funding guidelines. A new Statement of Work (SOW) was
received from NASA and will go into effect through a unilateral change order.
MTI is preparing the cost proposal to correspond to this SOW.
Agreement was reached with NASA regarding the rapid reporting of discrepancies
,-jnd failures of components, parts, assemblies, subassemblies, and engines. A
Discrepancy Notice will be completed and submitted to the Manager of Product
Assurance (at MTI) whenever an integral part of the system does not comply
with the intended configuration, fit, or function.
A Failure Notice and Analysis Report will be completed and submitted to the
llanager of Prod uct Assurance (MTI) whenever a system, subsystem, component, or
part fails to perform its intended function during testing, operations, or end
use.
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A program quarterly review,which was held at USS (Malrao, Sweden) on August
21-23, was attended by MTI/AMG/USS/NASA.
On September 12 and 13, an in-depth review of USS Product Assurance status was
conducted by MTI. Final preparation of the program Product Assurance Plan
will resume after the October CCM. The ASE Product Assurance Manager is now
committed to devote more time to complete the required product assurance
plans, direct their implementation by the subcontractors, and to perform
subsequent audits.
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RKMD
A P P E N D I X A
S T I R L I N G E N G I N E
D R I V E SYSTEMS TEST RIG
PROGRESS REPORT
H I G H W A Y V E H I C L E SYSTEMS
CONTRACTORS CO-ORDINATION M E E T I N G
23 - 25 OCTOBER 1979
HYATT REGENCY DEARBORN HOTEL, D E A R B O R N , M I C H I G A N
AUTHORS A.R.CROUCH/V.C.H.POPE
R I C A R D O CONSULTING E N G I N E E R S LTD.
B R I D G E WORKS
SHOREHAM-BY-SEA
SUSSEX
This presentation is sponsored by the U.S. Department of Energy
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A C K N O W L E D G E M E N T
T h e work reported i n t h i s presentation w a s performed b y Ricardo
C o n s u l t i n g Engineers Ltd., a s sub-contractor t o K B U n i t e d S t i r l i n g
(Sweden) & Co., who themselves are sub-contractors to M e c h a n i c a l Technology
I n c o r p o r a t e d , 368 Albany-Shaker Road, Latham, New York 1 2 1 1 0 . Mechanical
Technology Incorporated i s t h e Automotive S t i r l i n g Engine Development
Program p r i m e contractor t o t h e National Aeronautics a n d Space
A d m i n i s t r a t i o n ' s Lewis Research Center, Cleveland, Ohio M135. under p r i m e
c o n t r a c t No. DEN3-32. The program is part of the U.S. Department of Energy,
D i v i s i o n o f Transportation Energy Conservation, Heat E n g i n e Highway V e h i c l e
Systems Program.
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raoiuONSII HN(. tN..INI I »
A B S T R A C T
T h i s is a review of'the work in progress to achieve a quieter
c o u p l i n g arrangement between the two crankshafts and the main d r i v e shaft
i n the 'U' form S t i r l i n g powered engine. Knowledge gained from t h i s
i n v e s t i g a t i o n w i l l b e incorporated into t h e design o f M O D 1 a n d M O D 2
engines which are part of the overall program.
An e x i s t i n g P40 U n i t e d S t i r l i n g engine has been adapted as a test
u n i t t o accept a l t e r n a t i v e gear forms, w i t h p l a i n a n d r o l l i n g contact
bearings, a twin l i n k driv e, a d elta plate drive and a chain drive.
The engine conversion, the test rig i n s t a l l a t i o n and noise
m e a s u r i n g equipment a r e described.
T h e t e s t program started i n J u l y 1979, i s progressing a s p l a n n e d
a n d w i l l be completed by March 1980. To date the noise l e v e l s of ^
d i f f e r e n t gear forms have been measured, mounted i n both p l a i n a n d r o l l i n g
contact bearings. Gears w i t h very s m a l l teeth (0.8 module) gi ve the
lowest noise l e v e l at speeds below 30 rev/sec, and there is l i t t l e - noisel e v e l dif ference between the p l a i n and b a l l bearings for these gears. The
results obtained are for comparative purposes only and cannot be related
t o v e h i c l e d r i v e - b y levels.
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REASONS FOR TEST RIG
T e c h n i c a l Support f o r M O D 1 Design
M O O 1 i s t h e f i r s t S t i r l i n g engine t o b e designed w i t h i n t h e
Automotive S t i r l i n g engine program. I t i s s p e c i f i c a l l y designed f o r
automotive use and the f i r s t engine is scheduled to be ready for test in
e a r l y 1981.
The short tim escale allowed for the design of MOD 1 necessitates
the use l a r g e l y of e x i s t i n g technology. Hence the design of MOD 1 was
based i n concept o n t h e successful P b Q engine produced b y United S t i r l i n g ,
Sweden.
T h e P ^ t O engine h a s four pistons i n a square configuration which
actuate t w o p a r a l l e l crankshafts. Each crankshaft i s f i t t e d w i t h a gear
w h i c h d r i v e s a c e n t r a l common output shaft. The t w i n crankshaft systemi s sometimes referred to as a 'U' configuration.
The P^O engine however was designed for use m a i n l y as a research
and stationary engine. When t h i s design concept is used for automotive
a p p l i c a t i o n , t h e r o t a t i o n a l speed i s increased w h i c h tends t o increase
t h e drive t r a i n noise. Although t h e engine when i n s t a l l e d i n a c a r c a n
be completely satisfactory from the passengers' point of view, the gear
noise may be apparent outside the vehicle.
D r i v e System Noise Red uction
The geared system which couples the t w i n crankshafts to the output
c r d r i v e n shaft tends to be (subjectively) the predominant noise, as thecontinuous combustion system and S t i r l i n g cycle gives a smoother rate of
change of pressure than the i n t e r n a l combustion engine and therefore the
S t i r l i n g engine generally i s comparatively q u i e t .
The gear noise may be l a r g e l y caused by the c y c l i c nature of the
i n p u t load. Each crankshaft has two crankpins at 90° to each other, and
t h e crankshafts a r e phased t o give equal o v e r a l l f i r i n g i n t e r v a l s . Thereforeeach crankshaft and gear has a d r i v i n g and d r i v e n period d u r i n g one revolution.
When f i t t e d w i t h h e l i c a l gears t h e crankshafts a n d d r i v e shaft tend
t o move a x i a l l y w i t h respect to each other d u r i n g a cycle. There is also a
separating force between mating gears.
The drive system is then a unique combination of the geometrical
r e l a t i o n s h i p of the gears and p e c u l i a r c y c l i c torque i n p u t .
D r i v e Systems Test Rig Proposal
A test rig was therefore proposed to be representative of the MOD 1
e n g i n e and on which a l t e r n a t i v e crankshaft c o u p l i n g systems could be f i t t e d
and their noise l e v e l s measured.
A P * » 0 engine was used, to which a l t e r n a t i v e gear forms, l i n k s , a
p l a t e and a chain d r i v e could be fitted. For c y c l i c speed r e g u l a r i t y and
expediency for t e s t i n g , the engine was motored and was fitted w i t h dummyhaads pressurised with h e l i u m to s i m u l a t e the c y c l i c torque from an actual engin
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• N S l l l »M Nl.lh. I H-.
BENEFITS AND LIMITATIONS
BENEFITS FRCM TEST RI G
S u b j e c t i v e l y lower noise l e v e l s w i l l b e obtained f o r t h e d r i v e
system i n t h e a l r e a d y q u i e t S t i r l i n g engine.
M e a s u r e d noise l e v e l s w i l l b e obtained f o r a l t e r n a t i v e gear
tooth forms.
Measured noise l e v e l s w i l l b e obtained f o r alternative p l a i n a n d
r o l l i n g contact b e a r i n g s .
Measured n c s e l e v e l s w i l l b e obtained f o r a l t e r n a t i v e l i n k , c h a i n o r
p l a t e d r i v e s .
L I M I T A T I O N S OF TEST RlG
I t must be noted however that all the noise level are for
comparison w i t h each other only
- they are not absolute
- they are not measured on a powered engine
- they are not measured in a vehicle and cannot be compared
with current vehicle drive-by noise levels in any way.
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RI^RDCCOMSUI UNO > NGIN' I 1 •
ADVANTAGES OF THE U CONFIGURATION
T h e S t i r l i n g c y c l e , a s d e v e l o p e d b y U n i t e d S t i r l i n g , r e q u i r e s e a c h
of the f ou r p i s t o n s to be p h a s e d at 90° w i t h r e f e r e n c e to the a d j a c e n t
p i s t o n . B y h a v i n g t h e c y l i n d e r s p a r a l l e l t o e a c h o t h e r w i t h a t w i n
c r a n k s h a f t s y s t e m , t h e h e a t e r h e ad d e s i g n i s s i g n i f i c a n t l y s i m p l i f i e d
c o m p a r e d w i t h a Vee c o n f i g u r a t i o n , and becomes m o r e a m e n a b l e to m a s s
p r o d u c t i o n t e c h n i q u e s .
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U FORM ENGINE
Courtesy KB U n i t e d S t i r l i n g (Sweden) AB £ Co
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R K 3 R D OCONSULTING CNOWUM
T E S T U N I T
The test u n i t is based on a PkQ crankcase, m o d i f i e d to accept new
crankshafts, m a i n d r i v e shafts, front and r e a r spacer p l a t e s and a sump
adaptor p l a t e .
A l t e r n a t i v e gears and a c h a i n d r i v e may be f i t t e d at the d r i v e e n d .
A t w i n l i n k d r i v e a n d d e l t a p l a t e d r i v e m a y b e f i t t e d a t t h e free
e n d .
The d r i v e end space p l a t e a l l o w s b a l l b e a r i n g s or a n g u l a r contact
b e a r i n g s (to control end float) to be t e s t e d w i t h the m i n i m u m of r e b u i l d
a s a l t e r n a t i v e s t o t h e o r i g i n a l p l a i n b e a r i n g s .
O i l jets spaced a t s t r a t e g i c p o s i t i o n s a l l o w o i l t o b e d i r e c t e d
i n t o the gear mesh or the e x i t face, by e x t e r n a l l y mounted control t a p s .
T h e crankcase assembly i s f i t t e d w i t h ' d u m m y1
heads p r e s s u r i s e d
w i t h h e l i u m , t o s i m u l a t e t h e c y c l i c pressures i n t h e powered S t i r l i n g
cycle.
The e n g i n e was not used as a powered S t i r l i n g c y c l e u n i t in o r d e r
t o m i n i m i s e c y c l e t o cycle pressure v a r i a t i o n s , a n d i n order t o a v o i d t h e
l a r g e heat rejection i n t h e test c e l l .
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DRIVE SYSTEMS TEST UNIT
MODIFIED P40
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RI0PDQCONSULTING tNGUftCftf
TORQUE CURVE COMPARISON
The two curves show the torque v a r i a t i o n between a complete d r i v i n g
e n g i n e u s i n g its own h e a t i n g source, and a motorised engine(using h e l i u m as
a working medium)driven by an electric dynamometer.
The curves show that on a motorised engine there is more negative
work, therefore more torque reversals, hence crankshaft r e v e r s a l s and gear
tooth clash. However t h i s test u n i t is only a means of p r o v i d i n g a constant
load and torque cycle, to allow various d r i v e arrangements to be f i t t e d
and compared.
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CYCLIC TORQUE AG A I N ST C R AN K ANG LE
Torque Curve Variation
0
Stirling Powered Engine
Meany torque
,0utput shaf t ro
Onecrankshaft
oo
us
CO
0)-a0)
to
aic
0
Motored Test R ig
'\ I
Onec ranksha f t
•Output" shaft
X)(U
cr>
CD
in0)
4->u3O
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RlflRDOCOMMUTING CHOHiEEMS
T E S T C E L L
The test c e l l contains the test u n i t , with an acoustic hood
which can be lowered over the u n i t during noise measurements.
T h e test u n i t i s motored b y a s w i n g i n g a r m e l e c t r i c dynamometer
T h e heat generated d u r i n g testing i s l a r g e l y d i s s i p a t e d through heat
exchangers in the coolant and l u b r i c a t i o n system.
The h e l i u m required to pressurise the 'dummy' heads is stored
outside t h e test c e l l i n g a s bottles.
The test c e l l also contains sound recording equipment and a
control console.
Microphones are located at the free end of the test u n i t , the
d r i v e end and the r i g h t side (looking on the d r i v e end). As a further
check, accelerometers are mounted on the front and rear covers.
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TEST CELL - SCHEMATIC
Microphone 3
Microphone 1
Microphone 2
Plan view
Accelerometerpositions
.Acoust ic hood
Speed and syncron is ingpulse
Side view
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C O N S U L ! I N C INMNIIRS
EFFECT OF MEAN CYCLE GAS PRESSURE ON NOISE .
A test was made at AO rev/s to investigate noise v a r i a t i o n at
mean cycle pressures from 30 to 100 bar. As the graph shows there is
no apparent fluctuation fn noise levels, only a g r a d u a l increase in noise.
I t v a s therefore decided t o l i m i t t h e cycle pressure t o 6 0 b a r t o a l l o wgreater use of h e l i u m content in the pressure bottles, and to m i n i m i s e
t h e l o a d i n g on the pistons and piston rod seals, in the absence of
d i r e c t cooling i n t h i s area.
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EFFECT OF MEAN CYCLE GAS PRESSURE ON NOISE
Speed at 40 rev/s.
C D
i
o >
CO00
Microphone 2
Microphone 1 —
60 80Mean Cycle Pressure - bar
100
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RMkL < L •COMSUIIlNf. t NI, •• • t H
1
EFFECT OF MEAN CYCLE GAS PRESSURE ON NOISE. .2
A s a f u r t h e r v e r i f i c a t i o n o f b e i n g a b l e t o r u n a t l o w e r m e a n
c y c l e g a s p r e s s u r e s , a f r e q u e n c y a n a l y s i s w a s t a k e n a t b l o a d C o n d i t i o n s .
E a c h s p e c t r u m i n d i c a t e d peaks a t s i m i l a r f r e q u e n c i e s . Therefore i n
c o n j u n c t i o n w i t h t h e p r e v i o u s m e a s u r e m e n t s , i t w a s a c c e p t e d t h a t i t
w o u l d be s a t i s * a c t o r y to run at a mean c y c l e p r e s s u r e of 60 b a r .
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EFFECT OF MEAN CYCLE GAS PRESSURE ON NOISE
Microphone Position 2
Speed - 40 rev/s
2 Module - 15°Helix Gears
100 bar 60 bar
80 bar AO bar
C D"D
70
60
50100 1k 10k
1/3 Octave Band Frequency - Hz
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CONSULTING ENGtMFER S
TESTING P R O C E D U R E
T h e engine i s started a n d r u n a t 2 0 rev/sec u n t i l a n o i l
temperature of 50°C and water temperature of2*0°C are reached. The
a u t o m a t i c water and oil control systems are then operativ e.
A q u a s i steady state r e c o r d i n g is made of the e n g i n e noise by
g r a d u a l l y i n c r e a s i n g the engine speed from 5 to 50 rev/sec over a
2 m i n u t e t i m e d u r a t i o n .
Tests are continued w i t h the e n g i n e r u n n i n g at 5 rev/sec for
a p p r o x i m a t e l y 5 m i n u t e s a l l o w i n g noise and v i b r a t i o n r e c o r d i n g s to be
taken. Tests are repeated at increments of 5 rev/sec, up to a speed of
50 rev/sec (i.e. 10 tests are recorded).
A t each of these test p o s i t i o n s , the m e c h a n i c a l losses are
checked and logged.
The acoustic hood is lowered over the u n i t for the d u r a t i o n of
the test.
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TEST CELL
•W9 9 9 9 9 9 0
Acoustic Hood in Position
During Tests.
9 9 9 9 9 Q Q
Acoustic Hood Removed
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R f c W T O. OMSUIllN . IN.lNIMS
SEQUENCE OF E N G I N E TEST B U I L D S
The sequence of test b u i l d s is shown opposite.
Currently the program is on schedule.
Following the b a s e l i n e tests, noise l e v e l s have been measured on
4 different gear forms, and w i t h a l t e r n a t i v e p l a i n b e a r i n g s and b a l l
b e a r i n g s on each gear tooth form. The results are shown l a t e r in t h i s
report.
The r e s u l t s are under constant review and the schedule may be
adjusted s l i g h t l y w i t h i n t h e contractual l i m i t a t i o n s .
O n e a d d i t i o n a l test i n t r o d u c e d w i l l b e t o f i t inductance
p r o x i m i t y gauges mounted on the front cover at the end of each shaft.
These gauges sense r e l a t i v e movement, and tests w i l l be made on the
shafts w i t h h e l i c a l and s t r a i g h t spur gears to measure and compare a x i a l
shaft movements.
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CO N SU M I N G E N G I N E E R S
SEQUENCE OF ENGINE TEST BUILDS
JULY 1979 BASELINE TESTS
2 MODULE - 15° HELIX
| 2 MOP STRAIGHT SPUR - 0.8 MOD 15° ELIX - 2 MOD 25°HELIX j
FIT BALL BEARING
2 MODULE - 15° HELIX
[ 2 MODSTRAIGHT SPUR - 0.8 OD 15° H E L I X - 2 MOD 25°H E L I X|
OCTOBER 1979 [ L I N K D R I V E |
2 MOD 25° HELIX - 2 MOD STRAIGHT SPUR^
|REMOVE L I N K S|
2 MOD 15 H E L I X SHAVED, DIN 6, CAST IRON
1 MOD 15° H E L I X AX I CON (ROLLING CONTACT)
I|FIT TAPER BEAR ING S|
[ 2 MOD 15° HELIX - BEST HELICAL - 2 MODSTRAIGHT SPUR |
FIT PLAIN BEARINGS
I[ D R I V E P L A T E|
MARCH 1980 j CHAIN DRIVE|
[ W R I T E R E P O R T )
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M'U )
A L L G E A R D R I V E
To couple together the three shafts of a square four u n i t , and to
accommodate the c y l i n d e r f i r i n g sequence, a gear d r i v e arrangement offers
t h e s i m p l e s t solution. T h e ma in advantage i s that i t allows t h e m a i n drive
shaft to act as a contra-rotating balancer shaft, by counteracting the
i n h e r e n t p i t c h i n g couple caused b y t h e d i s p o s i t i o n o f t h e crankshaft
b a l a n c e weights, a n d thus g i v i n g 100$ dynam ic engine balance.
Together w i t h t h e smooth cyclic torque output from t h e d r i v e shaft,
t h i s gives a power p l a n t almost free from v i b r a t i o n .
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ALL GEAR DRIVE
Gear Train
Viewed from Drive End of Engine
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G E A R F O R M S
Gears t e s t e d to d a t e were chosen to g i v e a w i d e b a n d of n u m b e r s
o f t e e t h a n d h e l i x a n g l e s .
The gears are:-
-O1 5 h e l i x .
_ o
46 t e e t h - 2 m o d u l e (12.7 DP)
1 1 5 t e e t h - 0.8 module(32 DP) 15" h e l i x .
48 t e e t h - 2 m o d u l e (12.7 DP) S t r a i g h t s p u r .
43 t e e t h - 2 m o d u l e (12.7 DP) 25° h e l i x .
Reference G e a r .
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GEAR FORMS
08 Module - 15 Helix 2 Module - 25 Helix
2 Module - 15 Helix
Reference Gears
2 Module - Straight Spur
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CONSULTING CNGiNCCHS
N O I S E AND VIB RATI ON TESTING - RECORDING
M I C R O P H O N E S
The microphones were all p o s i t i o n e d approx. 0.75m above floor
h e i g h t , w i t h microphone 1 approximately 1 m t o t h e sid e, microphone 2
a p p r o x i m a t e l y O.^m away from the d r i v e - e n d and microphone 3 a p p r o x i m a t e l y
0.5m away from the opposite end of the engine (all dimensions are taken
from the v e r t i c a l centre l i n e of the engine). S i g n a l s from the microphones
were monitored d u r i n g t h e tests u s i n g a sound l e v e l meter ( g i v i n g o v e r a l l
A - w e i g h t e d levels). After s u i t a b l e a m p l i c a t i o n , t h e s i g n a l s were
recorded on 3 channels of a 7 channel FM machine.
ACCELEROHETERS
The accelerometers were mounted on the d r i v e - e n d gear housing, and
on the front cover. S i g n a l s from these accelerometers were a m p l i f i e d and
i n t e g r a t e d t o g i v e v i b r a t i o n v e l o c i t y information, hich w a s recorded o n
a further 2 channels of the tape recorder.
The r e m a i n i n g 2 channels were used for speed and synchronisat ion
s i g n a l s .
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NOISE AND VIBRATION TESTING
1 Recording
Dynamometern
Speed & sync,signals
Vibrat ionsignal
amplif ier £integrator.
Soundlevelmeter.
Noisesignal
ampl i f ier
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CONSUITIHI. CMCNi t "
N O I S E AND V I B R A T I O N T E S T I N G - A N A L Y S I S
A n a l y s i s of the r e c o r d e d d a t a was p e r f o r m e d in one of 3 d i f f e r e n t
ways, d e p e n d e n t o n t h e t y p e o f t e s t p e r f o r m e d . N o i s e a n d v i b r a t i o n r e s u l t s
from the s t e a d y - s t a t e t e s t s ( r e c o r d i n g s m a d e at c o n s t a n t e n g i n e s p e e d and
m e a n gas p r e s s u r e ) were u s e d to o b t a i n 1/3 octave f r e q u e n c y s p e c t r a and
t o i n v e s t i g a t e t h e r e l a t i o n s h i p b e t w e e n t h e n o i s e o r v i b r a t i o n s i g n a l s
a n d t h e c r a n k s h a f t a n g u l a r p o s i t i o n a n d r o t a t i o n a l speed. F r e q u e n c y
a n a l y s i s was c a r r i e d out on a B 6 K 2 1 3 1 d i g i t a l a n a l y s e r . I n v e s t i g a t i o n
o f t h e r e l a t i o n s h i p s b e t w e e n t h e n o i s e a n d v i b r a t i o n s i g n a l s a n d t h e
c r a n k s ' s p e e d a n d p o s i t i o n w a s m a d e b y d i s p l a y i n g t h e n o i s e ( o r v i b r a t i o n )
s i g n a l , w h i c h m a y h a v e b e e n p r e v i o u s l y p a s s e d t h r o u g h a 1 / 3 r d o c t a v e
f i l t e r set, o n a n o s c i l l o s c o p e , t o g e t h e r w i t h a t r a c e s h o w i n g t h e c r a n k s '
a n g u l a r p o s i t i o n ( u s i n g t h e s y n c h o n i s a t i o n p u l s e ) . I n t h i s m a n n e r i t w a s
p o s s i b l e t o i d e n t i f y r e l a t i o n s h i p s between c r a n k s p e e d a n d f o r c i n g f u n c t i o n
f r e q u e n c i e s , a n d ( t o a l i m i t e d extent) t o i d e n t i f y t h e p h a s i n g o f t h e
l o w - f r e q u e n c y f o r c i n g f u n c t i o n s compared w i t h t h e c r a n k p o s i t i o n .
T h e r e c o r d i n g s m a d e d u r i n g q u a s i - s t e a d y s t a t e t e s t s ( i n w h i c h t h e
e n g i n e was g r a d u a l l y a c c e l e r a t e d over the s p e e d range) were u s e d to
p r o d u c e p l o t s of the o v e r a l l A - w e i g h t e d l e v e l s a g a i n s t the e n g i n e speed.
These p l o t s may be u s e d to o b t a i n comparisons between noise and v i b r a t i o n
l e v e l s for d i f f e r e n t b u i l d s over the w h o l e speed range.
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NOISE AND VIBRATION TESTING
2, Analysis
Speed
Svnc
Dig i t a l f requency analys isarid subsequent data storageon computer f i l e .
Quasi-steady state plots ofOvera l l level v Speed.
Osc i l l oscope display o f f i l t e redsignal and crank pos i t ion (From
sync, pulse.)
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RI0RLG
P R E L I M I N A R Y RESULTS - GEAR TESTS LEVELS
Result* of th* quasi steady-state tests for the b u i l d s w i t h
d i f f e r e n t gear d r i v e arrangements are shown. The plots are shown fort h e noise as measured at microphone p o s i t i o n 2, t h i s b e i n g the p o s i t i o n
closest to the gear housing. Results from the other microphone p o s i t i o n s
showed the same trends as those presented, but to a lesser degree.
B u i l d No 1, u s i n g the 2 module, 15° h e l i x 'reference' gears,
showed a steady increase in noise l e v e l w it h speed, the slope of the
curve when p l o t t e d on log scales b e i n g approximately 50 dBA/decade. T h i s
steady increase was m a i n t a i n e d up to a speed of 40 rev/s, above which speed
there was a s i g n i f i c a n t (- 2dBA) decrease in l e v e l to a m i n i m u m at
45 rev/s. W i t h further speed increase, the noise l e v e l increased w i t h
speed at a p p r o x i m a t e l y 60 dBA/decade.
The fine-toothed gears of 0.8 and 15° h e l i x angle r e s u l t e d in a
decrease i n t h e noise l e v e l compared w i t h b u i l d 1 o f a p p r o x i m a t e l y 2 £ d B A
over the whole of the measured speed range. The same trend of noise l e v e l
decrease and r i s e was demonstrated as for the reference gear b u i l d at
h i g h speeds (40 to 50 rev/s).
Use of the 2 module s t r a i g h t - c u t spur gears ( b u i l d k) gave noise
l e v e l s very s i m i l a r t o those o f t h e reference gear b u i l d a t speeds o f u p
t o 25 rev/s. Above t h i s speed however, there was a d i s t i n c t ' f l a t t e n i n g1
o f t h e noise a s speed p l o t , w i t h further increase i n speed causing l i t t l e
increase in noise l e v e l . The increase in l e v e l from 25 to 45 rev/s was
a 1.5 dB A, whereas for the reference gear b u i l d the corresponding
i n c r e a s e was 4 dBA.
O v e r most of the speed range (20 to *»5 rev/s) , use of the
2 module, 2 5 ° h e l i x angle gears r e s u l t e d i n noise l e v e l s a p p r o x i m a t e l y
l j d B A h i g h e r t h a n l e v e l s measured f o r t h e reference gear b u i l d .
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GEAR NOISE LEVELS
Q ua si- Steady State
Mean Pressure - 60 bar
Build 1 : Reference gearsBuild 2 : Fleron gears
2 module -15 o Helix0-8 m od ule-1 5° Hel ix
Build 4 S t ra ig ht -c ut spur gea rs— 2 moduleBuild 525°Helical gears.- 2module
Microphone Posi t ion 2
C DTD
U 100
a;
inina*
cDo
8020 30 40
Engine Speed - rev /s .
50
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RI0RDOCONSULTING IN..INFCHS
P R E L I M I N A R Y RESULTS - BALL VERSUS P L A I N B E A R I N G S
I n an attempt to reduce possible noise sources caused by
crankshaft and d r i v e shaft movement, the o r i g i n a l p l a i n bearings on the
r e a r crankshaft journals and d r i v e shaft were replaced by b a l l bearings
mounted in the rear spacer plate.
When the engine is running, the m a t i n g gears have a separating
force and the two shafts tend to move through t h e i r r a d i a l b e a r i n g
clearance. Each crankshaft is also subjected to a d r i v e n and d r i v i n g
p e r i o d d u r i n g one revolution. When f i t t e d w i t h h e l i c a l gears, the
crankshafts and driveshaft therefore also tend to move a x i a l l y . B a l l
b e a r i n g s w i l l l i m i t t h e r a d i a l movement a n d tend t o damp t h e a x i a l shaftmovement.
A l l four gear sets were tested with b a l l bearings over a
q u a s i - s t e a d y state test. Comparable noise l e v e l s w i t h the 0.8 module 15°
h e l i x gears a t a l l microphone positions a n d accelerometer position 1 a r e
shown w i t h p l a i n a n d b a l l bearings.
I t can be seen that although noise l e v e l v a r i a t i o n s were achieved ,
no s i g n i f i c a n t advantage with the b a l l bearing arrangement was apparent.
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GEAR NOISE LEVELS
Quasi - Steady State
Gears Tested - 08 Module - 15 Helix
Build 2:Plain bearing
Build 8 = Ball bearing
<CD-D
< U
o >
o >
^inl/>0>
•Dc
I
'Mic. po s i t ion 1
'Acc el , pos i t ion 1
20 30 40
Engine Speed - rev/s
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F U T U R E T E S T S 1
L I N K S A N D GEAR D R I V E
The crankpin layout throughout the engine is such that there
i s a 90° crankpin displacement on each crankshaft and a 90° displacement
between each crankshaft, making four power strokes (every 90°) for each
e n g i n e revolution. Due to the f i r i n g order sequence required by t h i s
system, a crankshaft is powered twice in succession (90° apart), and
then d w e l l s for 180° which gives an uneven cyclic torque in each
crankshaft. This i r r e g u l a r torque is transmitted by the gears (on an
a l l gear d r i v e arrangement), through the teeth, to the main d r i v e shaft.
W i t h the J i n k d r i v e the two crankshafts are coupled together
w i t h t w i n l i n k s , spaced at 90°. Theoretically t h i s w i l l allow the torque
f l u c t u a t i o n s l a r g e l y to be cancelled, g i v i n g a smoother torque d r i v e from
t h e geared crankshaft to the m a i n d r i v e shaft.
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LINK AN D G E AR D R I V E
Link and Gear Drive
Viewed from Front of Engine
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J l
F U T U R E T E S T S 2
D E L TA PLATE
The d e l t a p l a t e d r i v e , a l t h o u g h l i t t l e known and u s e d , c o u l d offer
a smooth and a s s u m e d q u i e t d r i v e s o l u t i o n . The p l a t e can accommodate other
a u x i l i a r y d r i v e p o s i t i o n s , such a s o i l p u m p , h y d r a u l i c p u m p , a n d water
p u m p , p r o v i d i n g t h a t e n g i n e speed i s acceptable.
T h e m a i n d i s a d v a n t a g e i s t h a t a l l s h a f t s w i l l r o t a t e i n t h e s a m e
d i r e c t i o n , l e a v i n g t h e e n g i n e w i t h a n u n b a l a n c e d p i t c h i n g moment. T o
r e g a i n f u l l o v e r a l l b a l a n c e t h e f i t m e n t o f a c o n t r a - r o t a t i n g s h a f t w i l l b e
necessary.
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DELTA PLATE DR IVE
Delta Plate Drive
Viewed f rom Front of Enaine
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ONMII I IN.. I Mt.lNII
F U T U R E T E S T S 3
C H A I N D R I V E
T h e c h a i n d r i v e w i l l b e f i t t e d t o t h e r e a r o f t h e u n i t , a n d i s a
3/8" t r i p l e c h a i n f i t t e d w i t h a double a c t i n g adjuster.
The t h r e e c h a i n sprockets are m a c h i n e d to g i v e a s t a g g e r e d t o o t h
p r o f i l e , and t h i s is a c h i e v e d by s p a c i n g each c h a i n s p r o c k e t 1/3 of a
t o o t h b e h i n d the a d j o i n i n g sprocket.
A g a i n t h e m a i n d i s a d v a n t a g e i s a s t h e d e l t a p l a t e d r i v e , f o r a l l
t h r e e s h a f t s r o t a t e i n t h e same d i r e c t i o n a n d a c o n t r a - r o t a t i n g b a l a n c e
s h a f t w i l l b e necessary.
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CHAIN DRIVE
Chain Drive
Viewed from Front of Engine
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R K a R D OCOHMILTHa C N Q M E E K S
C O N C L U S I O N S
Conclusions to be drawn from the results so far obtained may be
summarised as:-
1 . The operating condition of 60 bar mean gas pressure is representative
of all operating conditions. Operation at higher gas pressures
affects the overall level of noise and vibration measured, but doesnot s i g n i f i c a n t l y alter the 1/3 octave frequency spectrum shape.
2. At engine speeds up to approx. 30 rev/s, the use of fine-toothed
h e l i c a l gears results i n radiated noise levels t y p i c a l l y 2 i d B A
lower than those produced by any other tested gear system.
3. For speeds between 30 and ^5 rev/s, the use of straight cut spur
gears gives noise levels approximately 1i dBA lower than those of
the fine-toothed gears which were in turn approx. 2i dBA lower
than the reference b u i l d levels.
k. Inspection of the 1/3 octave noise frequency spectra shows a peak,
most l i k e l y due to a structural resonance of some form, at a
frequency of 630 to 800 Hz. This peak is the controlling factor
i n the subjective assessment (and the A-weighted overall level) of
the radiated noise.
5. Inspection of the noise and v i b r a t i o n signals from the
accelerometers have not yet been completely analysed.
6. Use of b a l l bearings at the d r i v e end of the 'shafts gave no
s i g n i f i c a n t overall red uction of either the noise or the v i b r a t i o n
l e v e l s , although there were l o c a l variationsof up to ± 3 dBA
depending on engine speed and measuring positions.
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1. R e p o r t N o .
NA SA CR-159744
2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtit le
AUTOMOTIVE STIRLING ENGINE DEVELOPMENT PROGRAM - QUARTERLY
TECHNICAL REPORT FOR PERIOD: JULY 1 - SEPTEMBER 30, 1979
5 . Report Date
March 1980
6. Perform ing Organization Code
7. Author(s)
Therese A. Derikart
Merton Allen
8. Performing Organization Report No .
MTI 79ASE101QT6
10. W o rk Unit No.
9 . P e r f o r m i n g O r g a n i z a t i o n N a m e a n d Address
Stirling Engine S y s t e m s Division
Mechanical Technology Inc.
968 Albany-Shaker Road
Latham, New York 12110
11. Contract or Grant No .
DE N 3-32
. Sponsoring Agency N a m e and A d d r e s s
U . S . D e p a r t m e n t o f E n e r g yO f f i c e of Transportation P r o g r a m sW a s h i n g t o n D.C.
1 3 . Type o f R e p o r t a n d P e r i o d C o v e r e dQuarterly Contractor R e p o r tJuly 1 - S e p t e m b e r 30, 1979
1 4 . S p o n s o r i n g A g e n c y Code
D O E/N A S A /0 0 3 2 - 7 9 /5
Notes
Quarterly Report. Prepared under Interagency Agreement EC-77-A-31
William K. Tabata, Transportation Propulsion Division. NASA Lewis
Ohio 44135
-10040. Project Manager,
Research Center, Cleveland,
This Quarterly Technical Progress Report covers the sixth quarter of activity after award of