Techtalk April June 2014 Powertrain

7/25/2019 Techtalk April June 2014 Powertrain

1/60

VOL. 7, ISSUE 2, APR - JUNE 2014

POWERTRAIN

l

l

l

l

l

l

l

l

l

History of Powertrain

Basics of Transmission

Hydraulic Hybrid

Hybrid Powertrain: Revolo

Alternate Fuel Powertrain

Powertrain Components: Variable Valve LiftSensors in Powertrain

Safety Features in Powertrain

Selecting Powertrain Technologies for the Future


2/60

Colophon

TechTalk@KPIT is a quarterly journal of

Science and Technology published by

KPIT Technologies Limited, Pune, India.

Dr. Vinay G. Vaidya

CTO,

KPIT Technologies Limited,

Pune, [email protected]

Kanchan Chivate

Reenakumari Behera

Kailash Shrinivasan

Smita Nair

Mindsye Communication, Pune, India

Contact : 9673005089

[email protected]

The individual authors are solely responsible

for infringement, if any.

All views expressed in the articles are those

of the individual authors and neither the company

nor the editorial board either agree or disagree.

The information presented here is only for giving an

overview of the topic.

For Private Circulation Only

TechTalk@KPIT

Guest Editorial

Chief Editor

Editorial and Review Committee

Designed and Published by

Suggestions and Feedback

Disclaimer

Anup Sable

Senior VP -

Automotive and Engineering,

KPIT Technologies Ltd.

Pune, India

Pranjali Modak

Priti Ranadive

Aditi Sahasrabudhe


3/60

Editorial

Scientist Profiles

Book Review

Articles

Guest Editorial 2

Anup SableEditorial 3

Dr. Vinay Vaidya

'Karl Benz' - 49

Smita Nair

Where Good Ideas Come From 37

The natural history of innovation

Steven JohnsonPriti Ranadive

4

Mayurika Chatterjee

10

Sushant Hingane

16Kailash Srinivasan and Milind Potdar

20

Sachin P. Pandit and Nandulal Kushabhau Gavali

26

Samir Sattigeri and Kiran Dakle

32

Subodh Pachghare

38

Shweta Kabade

44

Priyank Vijapur and Santosh Nalanagula

Ravi Ranjan and Naveen Manuel

History of Powertrain

Basics of Transmission

Hydraulic Hybrid

Hybrid Powertrain: Revolo


Powertrain Components: Variable Valve Lift

Sensors in Powertrain

Safety Features in Powertrain

Selecting Powertrain Technologies for the Future 50

Contents

TechTalk@KPIT, Volume 7, Issue 2, 2014

1


4/60

Guest Editorial

It is indeed a great pleasure for me to get this opportunity to write an editorial on Powertrain.

Powertrain as a domain is very close to my heart since childhood days. Memories are still fresh of

discovering an ethanol engine in the scraps market and struggling to get it to work while in

secondary school and then meeting another teenager who had created steam engine at home

using pressure cooker as the boiler to generate the steam.

No one can question the impact that the invention of powertrain has had on humanity. From the

initial steam powered vehicles to the modern gasoline and diesel powered engines, human beings

owe a lot to the power of this technology towards bringing us a better quality of life.

In the last 125 plus years, powertrains have made a progress from purely mechanical system to an

electronically assisted mechanical system (mechatronics), to very complex software driven

electronic systems. Today, thousands of parameters are internally computed using software in real

time to measure and then deliver accurately the fuel to the engine so that the engine delivers us the

best (or more appropriately the optimum) fuel efficiency bundled with performance and emissions.

Today more and more innovation is happening in connecting the powertrain via telematics to

external world to bring in even more fuel efficiency, safety and emission control.

While there has been a tremendous impact of powertrain on our lives in a positive way, it has also

now brought in a set of issues. Modern cities are plagued with traffic problems and as a result the

vehicles are spewing harmful gases and particulates while they stall in the traffic or move at a snail's

pace. This throws up challenges for innovators and we all know that cleaner options like the electric

vehicles are making slow but steady progress to replace the conventional powertrain and solve this

pollution problem.

While the electric vehicles offer a solution to the environmental issues, today the commercial

viability of the electric vehicles is questionable, largely due to the cost of the batteries. There have

been, some evidence of success in pockets that indicate that electric technology is here to stay and

shape the future of the mankind.

To supplement the electric powertrain there needs to be a lot of innovation going into the generation

of electricity in cleaner ways. On the horizon we have other technologies like fuel cells which are

commercially unviable now but present a great future for cleaner transportation.

Overall, faster transportation is here to stay.So, go ahead and enjoy this issue of TechTalk, where

you can explore this history of powertrain and also take a look at what future has in store for us.

Senior VP -Automotive and Engineering,KPIT Technologies LtdPune, India.

Anup Sable


2


5/60

Dr. Vinay G. VaidyaCTOKPIT Technologies Limited,Pune, India

Editorial

Please send yourfeedback to :[email protected]


3

Eric Morris, a grad student at UCLA in 2007, in his well-known master's thesis, wrote about the state of New York

and London during the late 1800s. One of his articles on the subject is aptly titled, 'From Horse Power to

Horsepower'. In the article, he mentions the top problem discussed in the international town planning conference

in 1898 in New York. To our surprise, that problem was getting rid of horse manure. One can only imagine the

euphoric feeling of many when Karl Benz invented an internal combustion (IC) engine in 1879, which led to thefirst automobile. Ironically, the invention of the automobile was thought to have solved the problem of pollution,

since automobiles would eliminate horse manure. Karl Benz was granted a patent on automobile in 1886. Benz

truly revolutionized transportation for masses.

In less than two decades after the grant of the first patent on automobile, came the flying machine at Kitty Hawk in

December 1903. This was another major event that revolutionized transportation around the globe. It is quite

interesting to compare the history of advancements in automobiles with those in aircrafts over the last century.

Advancements in automobile came from different directions. It included increase in horsepower, manufacturing

processes, mass production methods, auto transmission, tires, shock absorbers, comfort, communication, GPS,

as well as infotainment. From combustion side, we have come a long way to completely electronic ignition as well

as improving efficiency all the way to mid-30 percent. Starting with a speed of 4 km/h, we have now reached wellover 400 km/h.

Aircrafts have also made lot of progress. Starting with propellers, airplanes moved on to using jet engines. This

change led to breaking the sound barrier. From propellers to jets to supersonics is one way to look at it. The other

is to see increase in size and capacity to carry load. As technology advances, we lose the charm of new

technology and we start accepting it as the only way of life. Out of that acceptance, mental limits and boundaries

are built. This is where innovation stops.

Let us dream of a completely new era with new designs and no baggage of technology barriers.

The first dream is about an automobile. Let us come up with the following specifications for this dream car. It

should have an IC engine with more than 60% efficiency. It should have a range of 1500 km. It should cost lessthan 2 cents per km. The expectation for the top speed is 100 kmph. It should be 50% better for the environment

than present day cars.

The second dream is about an aircraft. We are going to be equally hard on the specifications. The first barrier that

we want to break is that of needing a runway to takeoff. Thus, the specifications would be as follows. It should be

able to takeoff without a runway. It should be able to carry 10000 kg of load. It should be able to carry 50

passengers. It should be able to stay up in the air without refueling for more than 3 weeks. Top speed should be

160kmph. It should be 70 % more environmentally better than a cargo airplane.

Which one of these would you say is impossible? Chances are good that you would say that the second dream is

less likely to come true. However, the good news is that second dream has come true. On Feb. 28, 2014, this

aircraft was unveiled by Hybrid Air Vehicles Ltd. This aircraft is 300ft long and is 60ft longer than the biggestairliners.

If the impossible is possible, how about taking the challenge of the first dream and making it a reality? We have not

seen much in the past 125 plus years in terms of radical breakthrough in the IC engine design. Isn't it time that we

make a major impact on IC engine efficiency and go beyond 60? Any takers for the challenge? Where have all the

innovators gone?


6/60


4


7/60

Journey of thePowertrain Technology

Mayurika Chatterjee

Automotive, Allied Engg.CREST,KPIT Technologies LimitedPune, India

Areas of Interest

Mechatronics & Control Systems


5


8/60

Engine

TransmissionDrive Shaft

Rear Wheel

Clutch U-joint Differential

Figure 1: Today's 'Wheeled Motor Vehicle' [Ref.1]

The central character of this article is a'wheeled motor vehicle' [Fig.1], which is self-propelled and carries passengers. This articlecovers the journey of this character. Theinteresting part is that ever since the 'wheeledmotor vehicle' is conceptualized, it hasevolved through decades. It took almost100,000 patents around the world to create

the modern automobile that we see around ustoday.

Going through the history, it can be said thatthere are major three aspects which broughtabout the evolution in the powertraintechnology, viz. government policies, publicdemands and the technology advancements.

I. Introduction

The concept of mobility is very important partin human evolution. During earlier times,people used animal carts as a means oftransport that was later replaced by the steamengine automobile. With passage of time andother technological advancements, mankind

demanded new and improved means ofmobility. Now, just traversing the distance wasnot the only intent but other factors such as thetravel cost, environmental impact, etc. wererequired to be considered. This resulted innew expectations from various domains of theautomotive industry.

One of the most important aspects of thesesystems was to connect a power source to thewheels of the carriage that carried people.This, as the name indicates, is basically thepowertrain system of a vehicle, a system that

powers the wheels. It consists of the parts thatproduce energy (then horse, now engine),some part that converts the energy to torque(then linkages, now transmission gears) andlastly, the part that sends that energy to theelement (drive shaft/mechanical linkages towheels) which ultimately propels the vehicle.

This article covers the evolution of thepowertrain systems including how and whythe powertrain technology has changed overtimes. Multiple scenarios and renewedexpectations discussed in the subsequentsections of the article led various technologies

to come together to make these changeshappen.

II. Let's move!

The story begins in 1769, with the advent ofsteam engine automobiles. In the early 19th

century, a variety of vehicles powered bysteam were on road, such as steam cars,buses and steam rollers [3]. It was a simplemechanical technique which did not need anysort of transmission mechanism. However, the

Figure 2:Cugnot's Steam Locomotive, 1769 [Ref. 2]

steam engine vehicles did not take off well.The design did not prove to be an ideal choicefor a road vehicle due to its high maintenancecost and its requirement for greater space.Other impact factor was the labor costs forcoal handling. The 'technology' did not helpmuch either with below par machiningtechniques. Its high power to weight ratio andthe slow start process (since steam needed tobe pressurized up to a certain amount for avehicle to start)were not suitable features for a

road vehicle. Cugnot built the first steam-powered self-propelled tricycle in the year1770. Next, a French inventor improvedCugnot's design and is also known to be thefirst one to invent differential gear [4]. In 1789,Oliver Evans was granted the first U.S. Patentfor a steam powered automobile [4].


6


9/60

Engine


Rear Whe

Clutch U-joint Different

Other aspects that affected the usage ofsteam engine were the 'government policies'and the 'public demands'. People experiencedthat the steam engines caused road damage,scared the horses (Yes! Pretty much a big dealat that time), blocked narrow lanes anddisturbed the locals at night due to their loudnoise. Hence, due to public demands and

other safety concerns, 'The Locomotive Act'(1865), famously known as the 'Red Flag Act'was passed. This included maintaining aspeed limit of 4mph (2mph in towns), apartfrom the compulsory presence of a man onfoot who led the vehicles by swaying a red flagand blowing a horn. This, along with thetechnological limitations discouraged itsusage in road transport.

However, until the early 20th century, thesteam-powered automobiles were beingcontinually developed in different parts of the

world. Between the years 1873 to 1883,Amedee Bollee Sr. designed and built manyadvanced steam cars which included basictransmission units such as shaft drive to thedifferential [4]. In the late 19th century, anothertechnology, the powerful petrol engines cameinto being. This was the last straw in thealready limping steam technology whichultimately ended the steam engine era.

A n o t h e r a s p e c t o f ' T e c h n o l o g yadvancements', plays an important role in thissect ion . I t i s these techno log ica ladvancements that helped make internalcombustion engine (ICE) technology assuccessful as it is today. From a labexperimental set-up to its vast usage in majorapplications (including in automotive), it hasset a strong foot-hold in the market.Experiments during the early 19th centurywere not successful due to lack of suitablefuels. In 1807, Swiss inventor, Francois Isaacde Rivaz invented an ICE using mixture ofhydrogen and oxygen as fuel and with electric

ignition. He patented it in 1807 and in 1808 hecreated the 'world's first internal combustionpowered automobile' [5]. But his design wasunsuccessful. However, the experiments tocreate successful ICE design continued. JeanJoseph tienne Lenoir patented a double-acting, electric spark-ignition internal

III. Rise of a long shadow

combustion engine fueled by coal gas in theyear 1860 [5].Subsequently, in the year 1863,Jean Joseph tienne Lenoir improved hisengine design by using petroleum as fuel andadding a primitive carburetor. This vehiclecreated history by completing a fifty-mile roadtrip [5].This design and de Rochas' designs ofa four stroke engine was improved by the

German engineers, Eugen Langen andNikolaus August Otto in the year 1866.

A decade later, Otto patented a four-strokeengine, popularly known as the "Otto cycle".Taking it one step further, in 1885, the duo ofGottlieb Daimler and Wilhelm Maybachdesigned a small, fast and light weight enginewith a carburetor through which gasoline gotinjected into a vertical cylinder [5]. Later, as it isgenerally known, Karl Benz was granted apatent on his design of a gas-fueled car in theyear of 1886. Several types of engines were

being developed and improved, like the two-stroke, four stroke, etc. This basically madethe system compact which resulted in a lowweight to power ratio. The commercial viabilityalso helped in its popularity. Also, dieselpowered engine was in development and inthe year 1893, Rudolf Diesel received a patentfor his engine design based on compressedignition.

Still, the powertrain technology had a long wayto go to be called as a successful technology.It had its own problem of inefficient engine

power transmission and thus the transmissionsystem (gears, clutches etc.) was invented [6].The transmission system allowed transferringthe engine power efficiently to the wheels, asper the requirement. The first one was manualtransmission, where the gears are changedmanually by the driver, as per the powerdemand. The first transmission invented by W.H. James in 1832 was a three-speedtransmission [7]. The modern transmission isattributed to the French inventors, Levassorand Panhard, who fitted their design to thePanhard motor car in 1895. The semi-

automatic type transmission becameavailable since 1937 and where known as 'theAutomatic Safety Transmission'. Thisfacilitated easy shifting of gears and hence aneasier driving. This system included the usageof planetary gears and conventional frictionclutch [8].


7


10/60

Engine


Rear Wheel


Figure 3 : Transmission system [Ref.9]

In parallel, in the electronics domain,technologies such as solid-state electronicsand the control theory were advancing. Thesetransitions allowed the usage of refinedelectronic systems to be used in solvingautomotive control and instrumentationchallenges. Until today, large scale applicationof control theory and modeling is observed inthe development of powertrain system whichstarted during the 1980s. The transmissionsystem also gained with such technologicaladvancements. For example, the automatictransmissions became a reality. The first true

automatic transmission developed by GMengineer was included in the 1948 Oldsmobileand subsequently, Ford installed theautomatic transmission design by BorgWarner in the 1950[8]. Today, the transmissionsystem is also electronically controlled and it isstill evolving.

For a very long time, IC engines ruled theindustry and many technologies were lost in itsshadow. But, change is inevitable. Increasingpollution and global warming was a majorconcern and people demanded better and

cleaner technologies. IC/diesel engineshandled significant changes to regulateemissions, but this did not stop the automotiveindustry to call upon a long lost technology-The Electric car.

Engine


Rear Wheel


IV. Revenge of an Electric car

For many, it might be a surprise that electricca rs we re ac t ua l l y bu i l t o r evenconceptualized before 21st century. In theyear 1837, Robert Davidson invented galvaniccell powered electric vehicle.

Plante. This led to further developments inelectric vehicle design as the rechargeablebattery allowed electricity storage on board.Andreas Flocken invented the first electric carin 1888, popularly known as the 'FlockenElektrowagen'. It was quite popular betweenlate 1800s and early 1900s, since it providedease of operation and comfort as opposed to

the gasoline cars available at that time.But, as mentioned earlier, 'technologicaladvancements' in the IC engine techniques,soon took over the electric car. The petroleumindustry too prospered during that time andbecame almost a monopoly in the market.Also, petrol vehicles could be quickly refueledand were cheaper as compared to the electriccar. These factors ultimately did not let electricpropelled vehicles sustain and they were lostin the dark.

In the late 1990s, the electric vehicle came into

the picture again when GM introduced anelectric vehicle known as the EV1. Thisbecame hugely popular due to its reasonableprice and performance. Later, 'The CaliforniaAir Resources' passed a mandate for theautomotive manufacturers directing them toproduce a fixed amount of electric vehicle peryear [10]. But this was short-lived due to somenegative publicity and pressure from large oilcorporations (which saw electric vehicle as athreat). Thus, the electric vehicles werescrapped and again lost its place. In themeantime, research on hydrogen car

technology began hoping to find another cleanalternative fuel technology. The technologyhas feasibility issues and currently extensiveresearch is going on to make it a commercialreality.

But, as fate would have it, the electric vehiclescame back with vengeance. The veryadvantages of the petrol engines were now itsmain handicaps. The fuel prices peaked andother governmental concerns caused a rise inthe degree of excitement towards electricvehicle. Innovators and entrepreneurs all

around the world now started to invest andexplore the electric vehicle technology. Theadvancements in the battery systems,electrical machines and control techniqueshelped in the renewal of the electric vehicles.There are many versions of electrified

There was a significant development inrechargeable battery technology in 1859 bythe invention of lead-acid battery by Gaston


8


11/60

Engine


Rear Whe

Clutch U-joint Different

vehicles available in the market today- Hybridvehicle, Plug-in hybrid, full electric vehicle andso on. The electric transmission technologyfurther increases the controllability andefficiency of the system. Research is alsobeing conducted for the In-Wheel motor typeelectric vehicles which further improves thevehicle stability.

Even though the electric vehicle is expensivethan the conventional system, technologistaround the world are making constantprogress in every aspect to make itcommercially viable for the common man.

Our central character of the article, 'wheeledmotor vehicle', has come a long way and asbeing predicted, still has a longer way to go.There will always be the three aspects-government policies, public demands and

V. Conclusion

technological advancements- which will pavethe way for a better future. There is also achance that other new aspects, such asavailabil ity of resources, unforeseendevelopments and concerns, might appear onthe scene which would decide the course ofevolution of the powertrain. Today, with launchof every new vehicle, powertrain capability

plays a major role. All the aspects and thecharacters described may eventually lead usto an electric Nano (low cost and environmentfriendly) with equally great high-tech featuresthat we have in today's conventional high endvehicle. May be, even our first ever vehicle,the steam powered automobile, may rise fromits ashes and advance to overtake theconventional and existing technologies, whoknows!

Bibliography

1. Image source available at ' http://expertshub.org/training-programs/advanced-ic-engine-technology/'

2. Carl Burgess Glasscock, Car History - A Vision Becomes Reality , an article available at

'http://www.americanautohistory.com/Articles/Article001.htm'

3. History of the automobile,Wikipedia, available athttp://en.wikipedia.org/wiki/History_of_the_automobile

4. The History of the Automobile available at http://inventors.about.com/library/weekly/aacarssteama.htm

5. Automobile History : History of Cars and Engines available at

http://inventors.about.com/od/cstartinventions/a/Car_History_2.htm

6. Chao-Hsu Yao, Automotive Transmissions: Efficiently Transferring Power from Engine to Wheels, Article in

Discovery Guides

7. Automobile History : History of Cars and Engines available at

http://inventors.about.com/od/cstartinventions/a/Car_History_2.htm

8. History of Automotive Transmission available at

http://www.diablotransmissions.com/history_automatic_transmission.html

9. Image from How Manual Transmissions Work, HowStuffWorks, Inc. available

athttp://auto.howstuffworks.com/transmission.htm

10.Andrew Xia,The Death and Re-birth of the Electric Car available athttp://www.theyoungwanderer.com/the

death-and-re-birth-of-the-electric-car-andrew-xia/


9


12/60


10


13/60

'From Manual to Automatic'

Area of interestsMathematical Modelling andSimulation, Control System.

Sushant HinganeAutomotive, Allied Engg.


11


14/60

Planet carrieris lockedin place

Outer planetgears turnring gear

Input fromtorque

converter

Small sun gearturns inner

planet gears

Inner planetgears mesh

with, and turnouter planet

gears

Large sun gear'freewheels'

I.Introduction: Trans-missionImpossible!Imagine yourself in a dirt track racing or in arace on a terrain that has steep slopes andsharp turns. Would you let your car decidewhat wheel torque to select? On the otherhand, consider yourself in bumper-to-bumpertraffic condition on a city road where there are

several traffic junctions and cross sections. Doyou want to keep on shifting the gears everytime you slow down or put the pedal to themetal? Or you want a car that is smart enoughto select the gear according to the acceleratorpedal position? The easiest type that will cometo you depends on which side of the Atlanticyou are. Around 80% of the car users in theUnited States prefer automatic gear shift overmanual, whereas 80% of the European carusers prefer manual transmission overautomatic [1]. But that doesn't meanautomatic transmission vehicles are not liked

in Europe. In fact, they are. Even in a growingautomobile market in India, the automatic geartechnology is much appreciated and is indemand these days. Ok, so moving further,let's gear up now, shall we?

In this article, we will discuss some of the typesof the vehicle transmissions and then you canmake a reasonable choice for yourself. We willsee the advantages and the drawbacks ofeach of the transmission technologies. Thecomponents that go into each type and theirfunctionalities are also covered in the article.

II. Manual transmission: Swaggerwith a stick

Before getting into manual transmission, let'sbegin with transmission. What exactly is atransmission system? The job of a vehicletransmission [2] [3] [4] is to take the torquepower coming from the engine and transfer itto the wheels, through various componentassemblies. Now, it is not just the 'transfer' ofthe torque, but it is also 'multiplication' orimprovement of the engine torque through the

gear set assembly. Lower gears provide high

Figure 1: Manual transmission system overview

torque but less speed, whereas higher gearsprovide less torque but high speed. Thus, for adriver, it becomes obvious that he needs hightorque power (i.e. lower gears) while movingthe vehicle from the rest, or to climb a hill, or incase if the vehicle is heavily loaded. Inordinary driving conditions, when the vehicleis already in motion and has acquired a

significant speed, the driver can shift to highergears to multiply the rotational speed comingfrom the engine, of course at the cost of thetorque power.

Manual transmission, sometimes referred toas Standard, is the simplest form of thevehicle transmission so far. In this system, theinterlocking gear wheels are so arranged that,by operating the selector lever, a driver canselect one of the several speed ratios betweeninput shaft and output shaft. And to allowsmooth shifting from one gear to another, aclutch is provided to disengage the engine

from the transmission. Figure 1 shows a blockdiagram overview of manual transmission.

A. ClutchThe first stage in the transmission of a car with

manual gearbox is a clutch. This concept is an

excellent solution for changing the gears while

the vehicle is moving. The job of a clutch is to

engage or disengage two rotating shafts, one

driven by the engine and other driving the

wheels. Purpose is to prevent the stalling of

the engine when vehicle has come to halt.

Most of the clutches work on the principle of

friction. When the clutch pedal is pressed, a

cable or a hydraulic piston pushes the frictiondisk from the gear side to get disengaged with

the disk from the engine side. This is the time

when the gear is to be shifted. Since the clutch

action is based on the friction, it is always

recommended to gradually press the clutch to

achieve a smooth transition.


12


15/60



Input fromtorque

converter

Small sun gear

turns innerplanet gears

Innergear

with, aouter

ge

Large sun ge'freewheels

Figure 2: Simple gear mechanism [Ref. 6]

Figure 2 shows a five speed transmission on astandard transmission vehicle. In this, themovement of the three collars (shown in pink)is controlled through the gear selector fork andin turn the gear selector lever [5].

III. Semi-automatic transmission-Manumatic or Autoual?

The transmission technique that isintermediate between manual and automatictransmission is semi-automatic or also knownas clutch less manual transmission or dual-clutch transmission. In this, the transmissiondoes not change the gear automatically, but iteliminates the need of a clutch for the geartransition.

In a semi-automatic transmission there aretwo clutches (so is called 'dual clutchtransmission'), but no clutch pedal. So, unlikethe manual transmission, where the driverpresses the clutch pedal and changes thegear with the selector lever, the clutches arecontrolled through electronic or hydrauliccontrols [6]. One clutch controls evennumbered gears and the other clutch controlsthe odd numbered gears, as shown in Figure3.

Figure 3: Dual clutch assembly [Ref. 7]

IV. Automatic transmission- Juststep on the gas!

The period from 1940 to 1960 was when thebiggies in the American automobile industry,like General Motors, Ford, and Chryslerstarted to adopt the automatic transmissionsystem (or simply automatics) and asignificant number of automatic vehicles

started to run on the roads. The automatictransmission can switch to the optimum gearwithout driver's intervention, except forstarting the vehicle and going into the reverse.For a person behind the wheel, the maindifferences in driving an automatictransmission are:

- There is no clutch pedal.

- There is no gear selector lever.

So, when a user has selected the 'Drive'mode, the gear changes automatically.

The Figure 4 shows a schematic overview ofthe automatic transmission line.

B. Gears

Manual transmission has relatively simplegear mechanism as compared to automatic.The gear shift procedure is to press the clutchpedal gradually, move the gear selector leverin the appropriate gear position and thenrelease the clutch pedal.

Figure 4: Automatic transmission system overview

A. Torque Converter

Unlike the manual transmission, there is no

clutch (and of course a clutch pedal) in an

automatic transmission. So, there is no

mechanism that will disengage the gearbox

input shaft and the engine crankshaft while in

a gear transition. If the engine crankshaft and

the gearbox input shaft are always connected,

the engine will stop as soon as the vehicle

comes at rest. To solve this problem, the

torque converter is used [7].

This device not only provides a mechanicaldecoupling of the input shaft (turbine output

shaft in Figure 5) and the engine crankshaft,

but also multiplies the engine torque up to the

ratio 3:1 with the help of fluid coupling.


13


16/60



Input fromtorque

converter

Small sun gearturns inner

planet gears

Inner planetgears mesh

with, and turnouter planet

gears

Large sun gear'freewheels'

Figure 5: Torque converter [Ref. 8]

As can be seen in Figure 5, the torqueconverter casing is filled with the transmissionfluid which takes the kinetic energy from thevanes of the rotating pump (impeller)connected to engine and transfers it to theturbine which drives the output shaft.

There is a high torque requirement when thevehicle has to start from the resting position.This initial push is provided by a small

component called a stator. The returning fluidfrom the turbine vanes to the impeller isredirected by the stator so that it aids therotation of the impeller, instead of impeding it.This action results in the increase in theturbine output torque and reduction in the heatloss in the fluid.

One more feature of the torque converter is anelectronically operated lock-up clutch. Whenthe vehicle reaches a high speed, the lock-upclutch gets activated to mechanically connectthe flywheel from the engine side and the

output shaft turbine. This brings thetransmission fluid temperature down byreducing the load on circulating the fluid. Inthis condition, the total engine speed istransferred to the planetary gearbox.

The planetary gear set or epicyclic gearsystem, consists of one or more sets of acentrally pivoted sun gear, a ring gear (orannulus) and several planet gears whichrotate between these. Similar to the solar-planetary system, the planet gears rotate

around the sun gear.

B. Planetary Gear Set

The vehicle can have more than one planetarygear set. By controlling the clutches and thebrake bands, one can prevent certaincomponents from moving. In doing so, theinputs and the outputs of the system can bealtered, thus, a change in overall gear ratio isachieved. The final gear ratio depends onwhich component is fixed, which component isdriving and which one is being driven. Thesimple planetary gear operation is explainedin Table 1.

These gears are automatically changed byusing hydraulics or solenoid techniques whichare discussed in a further section.

Table 1: Simple planetarygear operation [Ref. 9]

Sun gear

Planet carrier

Ring gear

Carrier

Sun gear

Ring gear

Stationary Power Input Power Output Rotational Rotational

directionSpeed Torque

Ring gear

Sun gear

Planet carrier

Same directionas drivemember

Same directionas drivemember

Opposite directionas drivemember

Planet carrier

Sun gear

Planet carrier

Ring gear

Ring gear

Sun gear

Reduced

Increased

Reduced

Increased

Reduced

Increased

Increased

Reduced

Increased

Reduced

Increased

Reduced

C. Transmission control unit.

The automatic transmission system iscont ro l led using the computer ized'Transmission Control Unit' ECU [10], whichperforms the following functions:

- Monitor the torque converter parameterssuch as transmission fluid temperature, slipratio, output shaft torque, etc.

- Monitor the wheel speed, engine speed,

engine torque, etc.- With the measured parameters of the vehiclespeed and engine speed, calculate the mostsuitable gear ratio for the transmission.

- Control the clutches and brakes in the gearsets to automatically shift the gears in order tomeet the prior calculated gear ratio.

Gear shift using electric solenoids.

The shifting of the gears in automatic is merelycontrolling the clutches and the brake bands inthe gear set. One of the ways to control them isusing electrical solenoids, a device that willconvert the electrical signal into a translationalmotion of a needle. This needle, when pushed

on the clutch band, will engage the gear.Gear shift using pressure solenoids.

For some transmission controls, the gearclutches and bands are hydraulicallycontrolled using hydraulic pressure actuatingsolenoids. These are the solenoids in whichthe translational movement of the needle iscontrolled through hydraulic pressure.


14


17/60



Input fromtorque

converter

Small sun gear

turns innerplanet gears

Innergear

with, aouter

ge

Large sun ge'freewheels

V. Automatic transmission: DrivingmodesEven though there is no 'gear selector' lever infully automatic vehicles, the drivers areprovided with various drive mode optionswhich even include the manual gear shiftmode. Some of the vehicles have a modeselector lever while some of the vehicles havea rotary knob. Mentioned below are someofthe important drive modes [10].

Park (P).This mode prevents the vehicle frommoving by locking the transmission. The parkmode engages the teeth on the notch providedin the parking brake to hold the vehicle still.Since it only locks the transmission, when inPark mode, the driven and non-driven wheelscan still rotate freely. That's why it is alwaysrecommended to use hand brake whenparked.

Neutral (N).In this mode, by disengaging allgear trains within the transmission, no torqueis transferred to the drive wheels. This modecan be selected just before a driver stops theengine.

Drive (D). This posit ion allows thetransmission to use all forward gears (totally 4to 8 depending on the vehicle) in high or lowrange.

Reverse (R).This mode can only be selectedwhen the vehicle is stationary and engine is atidle, allowing a vehicle to be drivenbackwards. Reverse is very similar to the firstgear as far as the gear ratio is concerned.

Overdrive (OD). In this mode, the torqueconverter lock-up clutch engages the flywheelas discussed before, to maximize the output

speed. Transmission will automatically selectthe gear according to the vehicle speed andthe throttle pedal position.

Sport (S). This mode, similar to the Drivemode, uses all the forward gears, but up shiftsand holds the gears at higher engine speed,thus, improving the acceleration. This mode isespecially used in the off-road conditions.

Manual (Steptronic) (+/-). Manual modeallows the transmission to operate in semi-automatics steptronic mode. The driver canshift gears up and down with the freedom of

manual transmission.Winter (W).This mode engages second gearinstead of first, while driving off from thestationary position, in order to avoid the loss oftraction due to wheel spin on snow or ice.

Brake (B). This mode works as an enginebrake while the vehicle is descending a hill by

slowing down the engine with the help of afriction-based retarder. This is a way ofslowing down the car without downshifting oreven without pressing the brake pedal.

VI. Conclusion Trans-mission

accomplished!

A brief comparison between manual andautomatic transmission is provided below.

Looks cooler and feels sporty. You need

manual transmission vehicle to win a

race.

Parameter Manual Automatic

Driver'sComfort

FuelEconomy

Control

Panache

Cost

Automatics win the race of

technology, but it is still not

something what the James Bondwould drive.

Costs less as compared to the

automatics.

Speaking in general, manual

transmissions are less convenient than

automatic. But again, it depends on how

comfortable/conversant the driver is with

the gear stick.

More fuel efficient.

Manual wins here. For a person who

wants a complete control over the wheel

torques, manual transmission provides a

level of flexibility to set the gear ratio

which is favourable in situations like

racing, off-road terrains, etc.

Costs more but some might feel

it worthy to pay more.

When it comes to the driver's

comfort, all the extra money that

is spent on the automatic

vehicles starts paying off.

Consumes more fuel than

manual.

The vehicle intelligence sets the

gear ratio, based on the

selection of various drive modes

by the driver.

Manual transmission is the old school methodwhere the (smart and skilful) drivers can enjoythe complete control over the power deliveredto the wheels. But they are not made foreveryone. While, the automatic transmissionsapplies so much advancement and ingenuityinto the computerized control that it brings outan excellent driving experience as the yearsgo by. So, the drivers who like to havecomplete control of their vehicle can go for themanual transmission, while those who preferan intelligent vehicle that drives itself can gofor an automatic transmission- pick yourchoice and set the wheels in motion.

Referencesth

[1] Blog: Automatic versus manual cars, by Tim Barnes-Clay, May 28 2013.th

[2] BOSCH Automotive Handbook, 8 edition- May 2011, Wiley, Chapter Drivetrainth

[3] William B. Ribbens, Understanding automotive electronics, 7 edition 2013,

chapter Digital Powertrain control systems[4] Davy Geuns, Description: Automatic gearbox, June 2003[5] A real transmission, part of How manual transmission works.

Available:http://auto.howstuffworks.com/transmission4.htm[6] Dual-clutch transmission, Wikipedia.[7] Inside a torque converter, part of How torque converter works.

Available:http://auto.howstuffworks.com/auto-parts/towing/towing

capacity/information/torque-converter2.htm[8] The transmission bible

Available: http://www.carbibles.com/transmission_bible_pg2.html[9]Automatic transmission- course 262 section 3, TOYOTA technical training

Available: http://www.autoshop101.com/forms/AT03.pdf[10] Automatic transmission, Wikipedia

Available: http://en.wikipedia.org/wiki/Automatic_transmission


15


18/60


16


19/60

Hydraulic Hybrid

Milind Potdar

Kailash SrinivasanCorporate Marketing

Areas of InterestContent, Marketing Communications,New Media, Digital Marketing.

Areas of Interest

Embeded System,Hardware & S/W Design, RTOS.


17


20/60

I. Introduction

II. Hydraulic Hybrid Systems

As the number of vehicles has increased onroad, so have the ill-effects on theenvironment. Vehicle manufacturers havecome to realize this and have been constantlyworking towards reducing the vehicularemissions without compromising on theperformance of the vehicle. These pursuits

lead to having electronic controls in engine fordiesel, petrol, and gasoline engines. However,it was found that having only an internalcombustion engine with electric power wasn'tgoing to be sufficient for reducing emissions.As a next step, the battery-operated electricvehicles were launched. But they were notfeasible for long drives as the battery was theonly source of power and the battery neededto be recharged frequently. This limitation ofthe electric vehicles gave birth to the idea of'hybrid vehicles'.

The hybrid vehicles use two or more

propulsion systems; integrating an internal

combustion engine with some second power

source. Hybrid vehicles utilize two sources of

power and energy to achieve optimal

propulsion and efficiency for a vehicle. One

type of hybrid is the motor and battery-

operated hybrids. These hybrids offer several

benefits, such as fuel efficiency, good mileage,

fewer emissions etc. The other hybrid sources

for powering a vehicle include gaseous fuels

like hydrogen, CNG, LPG, ethanol, hydraulics,etc. In this article, we will explore the hydraulic

hybrid vehicle system. A hydraulic hybrid

system uses pumps or motors to store energy

in hydraulic accumulators. Hydraulic hybrid

systems works well for heavy duty vehicles

and off-road vehicles, as they require large

space for the pumps/motors and the

accumulators.

Hydraulic systems are similar to conventional

hybrid electric vehicles in the sense that they

both improve fuel economy by utilizing the

energy generated every time a driver brakes,

also known as regenerative braking. However,

instead of storing energy in a lithium-ion

battery (like in battery-operated hybrids), the

hydraulic systems uses a hydraulic pump-

motor, reservoir, and accumulator with an

internal combustion engine. The energy is

used to move fluids from a reservoir into the

accumulator. As the fluid enters the chamber

there is a build-up of pressure, which turns into

compressed energy helping to launch the

vehicle.

The hydraulic hybrid systems are cheap and

fuel efficient as they can store energy quickly,

allowing them to capture more energy from the

braking. Hydraulic hybrid recovers up to 75%

of the vehicle's kinetic energy compared to the

25% for the electric hybrids. Hydraulic hybrids

are more effective and efficient for vehicles

that need to start and stop frequently. Hence, itbenefits commercial and heavy duty vehicle,

like garbage trucks, delivery trucks, and city

buses, as these vehicles need to start and

stop a lot while on their way.

III. Working Principle

As shown in Figure 1, hydraulic hybrid vehiclesystem consists of four main components [1]:

1. The working fluid

2. Reservoir, pump/motor (in parallel hybrid

system) or in-wheel motors3. Pumps (in series hybrid system)

4. Accumulator

ICE

Pow

ertra

in

split

Tran

smission

HYDMOTO

R

Fluid Gas

Fluid Gas

HYD

PUMP

Reservoir

Accumulator

Figure1: Block diagram of Hydraulic Powertrain


18


21/60

Like the motor and battery operated hybrids,the hydraulic systems are also configured asthe parallel hydraulic hybrid and the serieshydraulic hybrid. In a parallel hydraulic hybrid,the hybrid components (reservoir, pump andaccumulator) are attached to the conventionaltransmission and the driveshaft which drivesthe wheels. So, it is an add-on to the existing

drive train. The engine provides power to thewheels through the conventional transmissionsystem. This configuration allows thehydraulic system to assist the engine instopping and accelerating the vehicle. Thekinetic energy lost during braking is stored inthe hydraulic accumulators.

In a series hydraulic hybrid there is noconventional transmission and driveshaft. Theengine is not connected to the wheels and thepower is directly delivered to the wheels. Thepump acts as a motor and uses the high

pressure fluids from the accumulator to propelthe vehicle. As the hydraulic system itselfdrives the wheels, the gasoline engine can beshut off, unlike in the parallel hydraulichybrids, providing more fuel savings. Both, theparallel and the series configuration lead toimprovements in fuel economy, brake life,acceleration and emissions.

Figure 2 shows the actual hydraulic system invehicle developed by Peugeot and BOSCH.

Figure 2: Actual working model (Ref. 3)

IV. Conclusion

Hydraulic hybrid systems are lighter and

cheaper than the electric systems of similarpower. High power hydraulic systems arerobust systems. Hydraulic systems are perfectfor all the heavy-duty vehicles such as trucks,busses, military vehicles, etc. as they need tostart and stop frequently. The hydraulic hybridsystems can operate over a range of climatic

conditions when the right kind of oils is utilized.Hydraulic hybrid systems are fuel neutral -they can be applied to vehicles using differenttypes of fuel, like diesel, CNG, LPG, etc.Hydraulic hybrid technology offers improvedacceleration and reduced fuel consumption,brake wear and emissions [5].

Although the hydraulic hybrids are now findinga place in the market, adapting hydraulicsystems for commuter cars will prove to be abig challenge. The reasons are plenty.Small/passenger cars do not have thenecessary space to accommodate the bulkyair storage tanks that are found in largervehicles. Add to that the industrial-qualitynoise, which will also have to be drasticallyreduced to suit smaller cars. So, the wayforward will be to find a way to power to allelectrical systems in a vehicle, such as windshields, headlights etc., without relying on a

battery. Several companies are working on orhave plans to work on the hydraulic hybridvehicles. If their technology is successful, itcould prompt many manufacturers to go forhydraulic hybrids and it may potentiallychange the market for the commuter vehicles.

References

1. Hydraulic HybridsAvailable online at:https://en.wikipedia.org/wiki/Hydraulic_hybrid

2. How hydraulic hybrids worksAvailable online at: http://auto.howstuffworks.com/hydraulic-hybrid2.htm

3. Hydraulic Hybrid system, by BoschAvailable online at:http://www.bosch.fr/en/fr/newsroom_7/news_7/news-detail-page_12864.php

4. Improving the fuel economy by using Hydraulic HybridPowertrain in passenger cars by SakotaZeljko (Machines,Technologies, Materials: ISSN 1313-0226. ISSUE 4/2013)

5. Presentation, Hydraulic Hybrid Vehicle Technologies, byMichael Conrad, September 9, 2008.


19


22/60


20


23/60

Hybrid Powertrain: 'Revolo'

Sachin P. PanditRevolo Hybrid Program

Areas of interestSystem Engineering,Control Logic Development,& Performance Optimization of HEV

Nandulal Kushabhau GavaliHybrid Solution

Area of InterestsMotor Control,ECU Designs for Powertrain,& Automotive Embedded Applications


21


24/60

I. IntroductionThe current global warming, pollution, priceinflation and depletion of natural resourceshave led to a need for development of greentechnologies. The amount of pollution causedby vehicles and continued increase ingasoline price has resulted in a need forsearching alternate fuel options. Researchhas been ongoing since the time of conception

of the vehicle, to make it more efficient in termsof fuel usage and to make it moreenvironmental friendly. This has given rise toalternative technologies to the conventionalinternal combustion engines. One suchalternative developed is the hybrid vehicletechnology. A hybrid vehicle is the one in whichthe engine is acting as one power sourcewhereas the battery or fuel cell is acting asanother power source.

It is well known that hybridization of the vehiclereduces the total emissions caused by the

vehicle in its entire life. Hence, the hybridvehicle systems are useful to reducegreenhouse gases. 'Revolo', is one suchaffordable and innovative plug-in hybridelectric vehicle technology developed by KPITTechnologies. This plug-in, parallel hybridsolution transforms vehicles, enables motorand engine to work seamlessly for a fuelefficient, green vehicle. 'Revolo' maybe usedas a retro-fit solution and hence provides theadvantage of converting the existing on-roadvehicles into a plug-in hybrid. The productonce fitted will help improve fuel efficiency of

over 35%, reduce CO2 Emissions by over30% and resulting in net energy savings ofover 25%. The solution is applicable to a largerange of vehicles from a small 800cc gasolinehatchback to 3000cc diesel light commercialvehicle OR school bus. Given the way it isdesigned and engineered, Revolo is the mostfrugal plug-in hybrid solution available. Nowonder that KPIT Technologies has won manyprestigious awards for this innovativetechnology. Some of the awards include: WallStreet Journal's Technology Innovation Awardin 2011, and 'Best Implemented Sustainability

Innovation of the Year 2011' award at GlobalKnowledge @ Whar ton Innovat ionTournament.

The broader scope of the article is to study thedifferent types of hybrid powertrains availablein industry as well as the different componentsincluded in such powertrains. We also present

a case study on the innovative and patentedelectric-hybrid vehicle system, 'Revolo'. It isinvented, designed, developed, andmanufactured by KPIT Technologies.

Hybrid vehicles operate on a dual mode,wherein the power is provided by both, anengine and a motor. The motor is used to drivethe partial load which is carried by the engine.The motor is directly connected to engineeither through a belt-pulley drive or through agearbox assembly. In some designs, the

motor is placed on the shaft where it connectsto a differential gear box of the vehicle.Different types of motor technologies arebeing deployed into the hybrid vehicle system.

The batteries used as the second powersource for supplying power to the motor areLead Acid, Ni-MH (Nickel-Metal hydride), andLi-Ion (Lithium-ion) types. The ValveRegulated Lead Acid(VRLA) batteries are themost commonly used in industry. Good thingabout the VRLA batteries is that it can berecycled. Hence, the emission or waste

created due to these batteries is very low andcan be advantageous when compared toGasoline/Diesel/CNG engines. Li-Ion has avery good energy to weight ratio. It also has agood life over the lead acid batteries. Li-Ionbatteries have to be protected against the highrate of charge, high discharge, and hightemperature so as to use them into a safeoperational zone.

Today different types of hybrid configurations

are employed in vehicles. The majordifference is based on how the engine and themotor assist each other in the total operationof the vehicle. There are also differencesbased on the how much hybridization hasbeen used in the vehicle. These differences,based on the level of hybridization, arecovered

II. Scope of the Article

III. Background

IV.Different types of HybridPowertrain


22


25/60

in detail in the subsequent sections.

A Parallel Hybrid Topology

The parallel hybrid topology is shown inFigure1 [1]. In this topology, the motor isdirectly coupled to the engine through acoupling or a pulley-belt arrangement. Apower-electronic converter is the 3-phaseinverter, along with intelligence of applyingdifferent amount of torque based on thespeed-load condition of the vehicle. Theengine RPM is measured using an enginecrank-speed sensor. The vehicle speed ismeasured using a speed sensor. Thedifference in speeds always gives the gearposition in which the vehicle is running. This isthe indirect load measurement on the engine.The motor revolutions per minute (RPM) canbe varied and based on the speed of the motor

V. The different hybrid topologiesare as follows:

MotorController

3 phaseMotor

Wheel

IC Engine

Coupling

Figure 1: Typical Parallel Hybrid topology in a vehicle

torque applied can be controlled. The vehicle

can be tuned on chassis dynamometer for

various torque-speed operating points. The

speed differential created between the engine

RPM and the motor RPM will determine the

actual assistance applied.

B. Series Hybrid Topology

The typical series hybrid topology is as shown

in Figure 2 [1]. The engine is used to charge

the batteries in a running condition. The main

advantage of this system is higher efficiency.

The engine can be run at a constant speed or a

variable speed based on the charging current

required. Hence, it can be ensured that the

engine will always run at the highest possible

efficiency.

MotorController

3 phaseMotor

Charger

GeneratorEngine

Wheel

Figure 2: Typical Series Hybrid topology in a Vehicle

The vehicle will always run as an electricvehicle while the engine, generator, charger,and battery will be acting as a fuel cell. Themain limitation of this topology is that theaftermarket system assembly becomesdifficult. So, it can be advantageous if this hasbeen fitted by the OEM into the vehicle.

C. Series-Parallel Hybrid Topology

As name suggests, it is the mixed series andparallel hybrid topology. It is also known asPower-Split hybrid topology. The engine isdirectly coupled to the motor as well asgenerator for battery charging. Hence, thecapacity of engine will be higher thanwhatever is used in the Series-Hybridtopology.

A. Micro-hybrid

In micro-hybrid type vehicle, the engine will bestopped during high idle time and theregenerative braking is used to stop theengine instantaneously. The vehicle will startsimply by pressing the clutch paddle or anyother means. This will be advantageous interms of fuel economy and the reduction ofvehicle emission.

B. Mild-hybrid

The mild hybrid type vehicle is similar to amicro-hybrid with addition to torqueassistance to the engine. A typical example ofa mild-hybrid is the Honda Civic.

C. Strong hybrid

The strong hybrid consists of the mild hybridcomponents plus an electric launch. It meansthat the vehicle can launch in an electricalmode. The battery used is smaller than PHEVtype and generally it is less than 2KWhr rating.

Due to the smaller battery used the totalelectric range is less. A good example of astrong hybrid is the Toyota Prius.

VI. Level of Vehicle Electrification


23


26/60

D. Plug-in Hybrid Electric Vehicle (PHEV):

In this type of electrification, the strong hybridtype is added with a plugging feature. Theplugging feature means an external chargingfacility is made available. Higher capacitybatteries are used (> 2KWhr) in this type ofhybrid so that longer electrical range isachieved. A good example of a PHEV is the

KPIT 'Revolo'.E. Electric VehicleIn pure electric vehicle, there will be no engineavailable. The only source of power is theelectrical motor which generates the energyrequired to drive the vehicle. Higher capacitybatteries are used so as to achieve longerelectrical range.

A. Introduction of Revolo Hybrid System

'Revolo' hybrid is a plug-in parallel electric

hybrid powertrain developed by KPIT. Thispowertrain allows the engine and an electricmotor to supply torque to the wheels. Revolopowertrain can be adapted to either gasolineor diesel engine vehicles which can either beretrofit or be integral to the on-road vehicles.

The objectives of Revolo Powertrain are toincrease the fuel economy, reduce theexhaust emissions and to recover the brakingenergy.

The block diagram arrangement of the major

Revolo powertrain components is shown inthe Figure 3. It consists of the followingcomponents:

V I I . K P I T R e v o l o H y b r i dSystem[3][4][5]

Battery

Pack

Vehicle

Battery

Pack Engin

e

MC

U

DC-

DC

HCU

Charge

r

Motor

Figure 3: Block Diagram arrangement ofRevolo Powertrain System

I. Electric Motor:A compact size caged rotorinduction motor provides torque up to 25% ofthe vehicle engine rating.

II. MCU:Also referred to as the inverter whichprecisely controls the torque of the electricmotor as decided by the control algorithm.

III. HCU: Control logic for the completeoperation of Revolo powertrain resides in theKPIT designed Hybrid control unit (HCU).

IV. Traction Battery Pack: 48V DC batterypack provides the electrical energy sufficientto achieve the decided/predetermined hybridrange.

V. Traction Battery Charger: Chargerensures the charging of the hybrid batterypack with a predefined charging profile tomaximize the life of hybrid battery pack. Thischarger works with domestic power outlet.

VI. DC to DC Charger:48V DC to 12V DCconverter fulfills the load requirement of thevehicle's electrical system. This converter isrequired in those Revolo powertrainconfigurations where the 12V alternator isremoved from the vehicle.

B. Working Principle

There are certain operating zones of theengine where the exhaust emissions are veryhigh. The carbon content in the gases from theexhaust indicates the fuel economy of a

vehicle. Higher the carbon content, lower isthe fuel economy of the vehicle. Engine torquesharing at these high emission operatingzones results into lowering of the amount ofexhaust emissions which further leads to anincreased fuel economy.

Revolo powertrain works on the torquesharing principle. Electric motor provides thetorque assistance to the engine where theexhaust emissions are very high. Emissionsimulation tuning approach helps indetermining the low emission operating points

and the amount of motor torque beingprovided to the engine [2].

Revolo powertrain continuously operates inthe following modes:Hybrid traction, Enginealone and Regeneration.


24


27/60

ECM

Engine

HCU

MCU

Vehicle Sensors and

Switches

Motor

Battery

Pack

Figure 4: Overall Control Scheme of Revolo Powertrain

The control algorithm residing in the HCUdecides the mode of operation and thecorresponding amount of positive, zero ornegative torque command considering thedriving conditions. Driving conditions aresensed by the sensors and the switcheslocated in the vehicle. HCU communicatesthis torque command to the MCU which furthercontrols the operation of the motor,accordingly. Figure 4 shows the overall controlscheme of the Revolo powertrain.

C. Dynamometer Testing Results

With an optimized HEV control algorithm, theoveral l system ef f ic iency improvessignificantly. Figure 5 illustrates the change incarbon dioxide emissions because of motorassist on a particular zone of a drive cycle.Primary axis indicates the vehicle speed andsecondary axis indicates the carbon dioxideemissions. It can be observed that with theRevolo hybrid technology, the emissions arereduced almost by 40% in this operating zone.

Figure 5: CO2 emissions with Revolo and without Revolo

VIII. ConclusionThere are different types of hybrid topologiesthat have been experimented with. Also, thereare different amount of electrificationsavailable in the vehicle, from micro-hybrid to acomplete electric vehicle. KPIT 'Revolo' is oneof the PHEV types of hybrid system. It isdesigned such that, as a retro-fit application, it

will take minimum amount of time to install intoa vehicle. Revolo performance statistics areillustrated in Figure 6.

Figure 6: Revolo performance statistics

Emission reduction30%+

Fuelefficiency

improvement35%+

Cost of traveldecreases by

25%+

In Revolo, the torque assisting is designed insuch a way that the above parameters can bematched. Apart from the targeted parameters,the safety issues are also considered into thedesign and the selection of differentcomponents into hybrid system. Revolo is anentirely new and novel approach tohybridization. Till date, 14+ patents have beenfiled for the 'Revolo' technology across variouscountries. The patents are for both, noveldesigns at component level as well as at the

system level. The patent applications cover awider variety of novel ideas related to themotor, motor control, energy storage systems,and hybrid systems with lower powerrequirement for vehicle. Furthermore, theproduct is independent of the degree ofelectronic control of the base vehicle and canalso be installed in vehicles with a puremechanical powertrain.

D. Safety Considerations

Various safety considerations that are takencare of in the Revolo powertrain include overtemperature, over voltage, over current, undervoltage, short circuit, EMI/EMC compliance,vehicle ignition interlock and emergencymanual cutoff.

References1. Available online,

http://en.wikipedia.org/wiki/Hybrid_vehicle_drivetrain

2. U.S Patent no. 8,560,156, titled 'Power assisting

system'

3. U.S Patent no. 8,596,391, titled 'Method of

converting vehicle into hybrid vehicle'

4. U.S Patent no. 8,423,214, titled 'Motor assistance

for a hybrid vehicle'

5. U.S Patent no. 8,606,443, titled 'Motor assistance

for a hybrid vehicle based on user input'


25


28/60


26


29/60


Samir SattigeriHybrid Revolo

Areas of InterestAlternate Fuel &Advanced Technology inPowertrain Development

Kiran DakleHybrid Revolo

Areas of InterestVehicle/Component Homologation& Testing


27


30/60

StepperMotor

Pressure

Regulator

Gear Box Engine

CNG ECU

CNG FuelLine

CNG Tank

Refillingvalve

I. Introduction

II. Gaseous Fuel

Powertrain is the heart of an automotivedesign. Engine and transmission are the maincomponents of a vehicle powertrain. Enginegenerates power required to drive the vehicleby combustion of the fuel. This power is thenapplied to the drive the vehicle through thetransmission. Broadly, the two types of fuelsthat are used in the vehicle are gaseous fuelsand liquid fuels. Out of these, diesel andgasoline are the conventional fuels used in avehicle.

Energy, security, environmental effects andpollution, CO2 reduction, etc. are the keydrivers that are causing automotivemanufacturers to conduct research onexploring use of alternate fuels for driving thevehicles. The alternate fuels that can be usedto drive a vehicle can be broadly classified intotwo groups:

1. Gaseous Fuel 2. Liquid Fuels

In this article, we will take a detailed look atsome of the gaseous fuels, their powertrainmodifications, the technology roadmap andapplication, the pros and cons and thechallenges. This is followed by a brief look atthe liquid fuels and the hybrid and electricvehicles.

Now-a-days increasing numbers of vehiclesare seen running on gaseous fuels like CNG(Compressed Natural Gas), Propane / LPG(Liquefied Petroleum Gas), hydrogen, etc.Amongst them, CNG and LPG fuels are beingused widely [1].

A. Changes Needed in Base Vehicle

(Powertrain)Technically, vehicles running on eithergasoline or diesel can be retrofitted to run onthe dual or dedicated fuel mode. It is possibleto retrofit a vehicle that is already in use andnow automakers are also coming up with

factory fitted CNG / LPGv e h i c l e s . I n c a s e o f

CNG/LPG, accommodatingan add-on fuel mode in agasoline vehicle is easiercompared to the dieselvehicle. Retro-fitting an add-on fuel mode in a dieselengine vehicle need

modification of the engine from CI(Compression Ignition) to SI (Spark Ignition).This modification includes changes in thecylinder head, the piston, the cylinder, theignition system, the cooling system, etc [3].

Figure 1 below shows the basic layout of aCNG enabled vehicle.

StepperMotor

PressureRegulator

Gear Box Engine

CNG ECU

CNG FuelLine

CNG Tank

Refillingvalve

Figure 1: Basic Layout of a CNG Enabled Vehicle

Running a gasoline vehicle on hydrogenneeds a number of changes/modification inthe base powertrain like the valves,connecting rod, spark plug, ignition coil andintake manifold, etc. One example ofmodification is there placement of the normalspark plug with non-platinum tip plugs. Themodification costs would be about 1.5 times of

the current cost of the gasoline engine [2].

B. Technology Road Map

i. In Vehicle Technology: For CNG / LPGvehicles, it primarily started with the 'OpenLoop' system (without feedback) integrationwith carbureted vehicles. As time passed,stringent emission norms forced thistechnology to evade and then the 'Close Loop'system took the lead in market from 1998 to2010. Currently, the third generation systemcalled 'Sequential System' (Injection system)is becoming more popular due to its reliability

and at par performance with gasolinetechnology. Use of hydrogen as a fuel to runthe vehicle started with the supply of hydrogenthat was stored on-board to the engine. Then,considering the passenger safety (as on-board stored hydrogen is risky), the nextphase evolved which is enrichment of base


28


31/60

StepperMotor

Pressure

Regulato

Gear Box Engine

CNG ECU

CNG FuelLine

CNG Tank

Refillingvalve

fuel with onboard generated hydrogen.Currently, automotive industry is working onusing hydrogen fuel cell to run the vehicleswhich is safer and also helps keep theenvironment clean [3].

ii. Infrastructure Technology: Instead ofhaving one mother station and multipleoutlets, government should emphasis onhaving multiple mother station as retail outlets.This will increase fuel availability with correctpressure (in case of CNG) and will encouragepeople to go these greener alternate fuelvehicles.

C. Technology Selection and Application

Alternate fuels being a source of cleaner andeconomical fuel, they are now getting hugetraction in market. Automotive market ismainly divided in two streams i.e. passengervehicles and commercial vehicles. Alternatefuels like CNG, LPG and Hydrogen (in someextent) are seen being popular in thepassenger vehicle segment. Option to choosebetween the dual fuel and the dedicated fuelmode are available for the customers.However, commercial vehicles mostly run ondedicated fuel mode only [3].

D. Pros and Cons:

Alternate fuels are cleaner than theconventional fuels which help to protect theenvironment. Due to the complete combustionof the alternate fuels, we save energycompared to gasoline and diesel. Theoperating costs are lower than its conventionalcounter parts. As the end consumer isbenefited in monitory terms, the usage ofalternate fuels has been increasing. Thedrawback of alternate gaseous fuels is that thestorage of such high pressure fuel in vehicle isrisky. However, mandate of exercising safetycode of conduct lowers the risk to minimum.Also, installing the alternate fuel system on thevehicle requires high initial cost.

E. Rules & Regulations

Some government rules are already in placeto regularize the use of alternate fuels invehicles either by retrofit solutions for theexisting vehicles or by use of factoryfitted/installed alternate fuel kits on vehicle.

F. Challenges: Consumer Acceptance

Step wise action plan needs to be executed to

make alternative fuel as a first choice for thetransportation industry. Multiple studiessuggest that the considerations mentionedbelow will largely contribute in boosting thealternative fuel usage [4]:I .Government po l i c ies to p romotedevelopment and usage of alternate fuelsII. Facilitate local manufacturers to developtechnology in order to boost economyIII. Infrastructure development: Refillingstations, fuel pipe line density, etc.IV. Mandate to automakers for manufacturingalternate fuel vehicles.V. Tax incentives for vehicles enabled withalternate fuelVI. Individual contribution to protect theenvironment and conserve energy

Under the liquid alternate fuels, we will brieflylook at bio-diesel, LNG, ethanol and methanol.

A. Bio DieselBio diesel is domestically produced, non-toxic,biodegradable and a renewable fuel. It can bemanufactured from vegetable oils, animal fats,or recycled restaurant grease. It burns cleaneras compared to the petroleum diesel fuel.

Bio diesel is different from the vegetable andwaste oils that are used in fuel converteddiesel engines. Biodiesel is to be used in thestandard diesel engines. Biodiesel is adomestically produced. It burns clean and is arenewable substitute for petroleum diesel.

When biodiesel is used as a vehicle fuel, itincreases energy security, improves publichealth and provides a cleaner environment.

Biodiesel can be used alone or may beblended with petro diesel in any proportions.Blends of biodiesel and conventionalhydrocarbon-based diesel are mostcommonly distributed in the retail diesel fuelmarketplace. A system known as the "B" factoris used to state the amount of biodiesel in any

III. Liquid Fuels

fuel mix. For example, 100%biodiesel is referred to as B100,20% biodiesel, 80% diesel islabeled B20, 5% biodiesel, 95%diesel is labeled B5, and so on.Blends of 20% biodiesel andlower can be used in dieselequipment with no or only someminor modifications to the


29


32/60

StepperMotor

Pressure

Regulator

Gear Box Engine

CNG ECU

CNG FuelLine

CNG Tank

Refillingvalve

Biodiesel can be handled, stored andtransported without any risk.

B. LNG (Liquefied Natural Gas)

In a gaseous state, liquefied natural gasoccupies about 1/600th volume of naturalgas.LNG is odorless, colorless, non-toxic andnon-corrosive.LNG is flammable after itvaporizes into a gaseous state. The/volumetric/ energy density of LNG is 2.4 timesgreater than that of CNG or 60 percent of thatof diesel fuel.LNG achieves a higher reductionin volume as compressed to natural gas(CNG). Due to this, it is efficient to transportLNG over long distances, where there are nopipelines. Cryogenic sea vessels or cryogenicroad tankers are specially designed carriersfor transporting LNG [5] [8].

LNG is used to transport the natural gas to themarkets. It is then re-gasified and distributedas pipeline natural gas. LNG maybe used innatural gas vehicles. However, generally,vehicles are designed to use the compressednatural gas. The relatively high cost ofproduction and the need to store the gas inexpensive cryogenic tanks has hindered thewidespread commercial use of LNG.

C. Ethanol

Ethanol (CH3CH2OH) is a clear, colorlessliquid and a renewable fuel. It is made fromvarious plant materials collectively known as"biomass." It is also known as ethyl alcohol.Ethanol in a low-level blend is used tooxygenate the fuel and reduce the air pollutionin more than 95% of the U.S. gasoline. Ethanolis also available as E85, or high-level ethanolblends. The flexible fuel vehicles are the onesthat can run on high-level ethanol blends,gasoline, or any blend of these. The blender orthe fuel supplier mixed the Ethanol with thegasoline before distributing it to the fuelingstations [5].

Due to the higher octane number that Ethanolhas as compared to gasoline, it providespremium blending properties. Low-octanegasoline is blended with 10% ethanol to attainthe standard 87 octane requirement. Ethanolcontains about 30% less energy thangasoline. E85 contains about 25% less energythan gasoline. High-level ethanol blendscontain less energy per gallon than doesgasoline, to varying degrees, depending on

is spills on the surface orwhen released into theenvironment. It is safer thanpetroleum diesel because itis lower combustion point.The flashpoint for biodiesel ishigher than 130C, whereasit is about 52C for petroleumdiesel.


30

powertrain [5] [6].

As compared to petroleum diesel, use ofbiodiesel in a conventional petroleum dieselengine substantially reduces tailpipeemissions of unburned hydrocarbons (HC),carbon monoxide (CO), sulfates, polycyclicaromatic hydrocarbons, nitrated polycyclicaromatic hydrocarbons, and particulatematter (PM). All the engines that aremanufactured in 2010 and later are required tomeet the emission standards irrespective ofwhether they are running on biodiesel, diesel,or even natural gas. Selective catalyticreduction (SCR) technology, which reducesnitrogen oxide (NOx) emissions to near zerolevels, makes this possible. For these newtechnology engines, the emissions from dieselfuel are comparable to those from biodieseland are extremely low. These new technologyengines are some of the cleanest engines on

road. B100 provides the most reduction inemissions, but lower-level blends also providesome benefits. B20 has been shown to reducePM emissions 10%, CO 11%, and unburnedHC 21% in older engines. Greenhouse gasand air-quality benefits of biodiesel areroughly commensurate with the blend. B20use provides about 20% of the benefit of B100use [5] [7].

Biodiesel improves fuel lubricity and raises theCetane number (measure of combustionquality) of the fuel. The lubricity of the fuel

prevents the moving parts of the diesel enginefrom wearing out prematurely. The lubricity ofdiesel fuels can be increased by use ofbiodiesel at blend levels as low as1%.However, before using biodiesel be sureto check your engine warranty to ensure thathigher-level blends of this alternative fuel donot void or affect your engine.As biodiesel is nontoxic, it causes lessdamage as compared to petroleum diesel if it


33/60

StepperMotor

Pressure

Regulato

Gear Box Engine

CNG ECU

CNG FuelLine

CNG Tank

Refillingvalve

the volume percentage of ethanol in the high-level blend. A lower octane number preventsengine knocking, thus, ensuring drivability [5].

D. Methanol

Methanol (CH3OH) is also known as woodalcohol. As an engine fuel, methanol haschemical and physical fuel properties similarto ethanol. Methanol maybe one of thealternatives to the conventional transportationfuels. Methanol is cheaper to produce ascompared to the other alternative fuels.Methanol has a lower risk of flammabilitycompared to gasoline. Methanol also offersimportant emission benefits as compared togasoline. It can reduce hydrocarbonemissions by 30 to 40 percent with M85 and upto 80 percent with M100 fuels. Since the early1990s, the use of Methanol in vehicles hasdeclined drastically. Automakers are no longer

interested in manufacturing methanol vehicles[5] [9].

Under the Energy Policy Act of 1992,electricity is considered an alternative fuel.Electricity can be produced from variousprimary energy sources. Plug-in vehicles arecapable of drawing electricity from off-boardelectrical power sources (generally theelectricity grid) and store it in batteries.Though not yet widely available, fuel cellvehicles use hydrogen to generate electricityin a clean manner onboard the vehicle.

In a plug-in electric vehicle, energy is stored inthe onboard rechargeable batteries. Thisenergy is used to power the electric motor.Although vehicles that run only on electricityproduce no tailpipe emissions, there areemissions associated with the production ofelectricity itself. Fueling plug-in vehicles withelectricity is currently cost effective comparedto gasoline, especially, if drivers takeadvantage of off-peak rates offered by theutilities.

Many plug-in vehicle owners prefer chargingtheir vehicles at home (or at fleet facilities, inthe case of fleets). Some employers offeraccess to charging at the workplace. At someplaces, plug-in vehicles have the facility toaccess public charging stations at libraries,shopping centers, hospitals, and businesses.

IV. Electric & Hybrid Vehicle

However, charging infrastructure has beenimproving recently. The advancement in thesecharging facilities is making chargingconvenient and allowing the driver to coverlonger distance ranges. This is giving thedrivers confidence to meet their needs by useof the plug-in vehicles [10].

Vehicles that run on alternate fuels can costless, reduce emissions, and reducedependence on foreign fuels. Alternate fuelssuch as Natural Gas, Ethanol, Petroleum Gasand Bio-diesel have a very bright future in thewake of growing concern over the health of ourenvironment. The technologies like electricand hybrid vehicle have been in the market fora while now. However, to make them moresustainable additional research is required onbattery technology since they are costly andneed frequent charging.

V. Conclusion

References

1. Semin, Rosli Abu Bakar, A Technical Review of Compressed Natural Gas as an Alternative

Fuel for Internal Combustion Engines, American J. of Engineering and Applied Sciences 1 (4):

302-311, 2008, ISSN 1941-7020

2. Alternative Fuels: An Energy Technology Perspective, IEA/ATO working paper, Paris:

International Energy Agency, 2010.

3. Ross Braun, Doug Karlen and Dewayne Johnson, Sustainable Alternative Fuel Feedstock

Opportunities, Challenges and Roadmaps for Six U.S. Regoins, Soil and Water Conservation

Society, September 2010.

4. Clean Cities Program of U.S dept. of Energy.

Available online at: http://www1.eere.energy.gov/cleancities/

5. Department of Energy

Available online at: http://www.energy.gov/

6. Alternative Fuels Data Centre

Available online at: http://www.afdc.energy.gov/fuels/biodiesel_basics.html

7. Biodiesel, Wikipedia

8. Liquefied Natural Gas, Wikipedia

9. Methanol, Wikipedia

10. Heejay Kang, An Analysis of Hybrid-Electric Vehicles as the Car of the Future,

Dept. of Science, MIT, June 2007


31


34/60


32


35/60

Powertrain Component:Variable Valve Lift

Subodh PachghareCRESTKPIT Technologies LimitedPune, India

Areas of InterestHigh Performance Computing,Parallel Programming,Operating System Internals & Automotive

,


33


36/60

I. Introduction

Today's modern car engines are the bestexamples of precision control systems, andform a crucial part of powertrain, comprisingtransmission, drive shafts, differentials andfinal drive system. In this article, we will focuson micro-components of the engine,especially the parts that help the engine to

breathe. Inlet and outlet valves are the onesthat allow the engine to inhale air-fuel mixtureand exhale burnt gases respectively, thus, inturn producing rotational power by means ofexpanding gases.

Figure 1: Basic Engine Assembly (Ref. 1)

II. What are Engine Valves?

III. How Variable Valve Timing

Works?

To understand what exactly valves do, we willtake a look at Figure 1. Valves are controlledby camshafts having lobes designedspecifically to tap the valves that are reversetensioned by springs. This peculiar tapping bylobe opens the valves inside the cylinder up toa particular depth defined by the geometry ofthe lobe. As soon as this lobe rotates, the

springs cause the valve return to its originalposition. Both intake and exhaust cams areoperated by timing belts, which are againdriven by the engine power produced in thelast cycle. Each camshaft rotates once forevery two rotations of the crankshaft.

As explained earlier, today's engines canregulate opening of valves. As explained inSection II, all valves open at the same timewhen the lobe rotation hits each valve. Now, ifyou want to specifically control the timing anddelay the opening of valves of the exhaust,you will need a separate control mechanism

on exhaust camshaft. Variable valve timing isachieved by cam phasing or by using multiplecamshafts. Both the systems employ heavyamount of sensors to detect optimal timingsand act accordingly.

Based on the crank-shaft rotational speedsensor and ECU (Electronic Control Unit), thecar decides the timeframe for which to openthe exhaust valves and the intake valves. Cam

phasing takes input from the crankshaftpositional sensor, which in turn retards thetiming of the camshaft, thus, causing morepotent explosion of air-fuel mixture. Thisresults in high torque in the given RPM(revolution per minute) bracket. Cam phasingonly works on the concept cam phase angle.However, during recent times, cam phasing isknown to have some limitations. Variablelobes cannot be used in cam phasing due tothe oscillating angle position of the cam shaft.Early opening of valves (advance stage) canbe done by rotating the cam angle in the clock-wise direction while delayed opening of valves

(retard stage) can be done by rotating the camangle in a counter-clock wise direction [2].

IV. Disadvantages of Pure Vvt

Systems, Need for Variable Valve

Lift & Design

Only advancing and retarding of a valvedoesn't result into optimum torque delivery inhigh/low rpm range. Design of lobe can bealtered to enable change in lift height of thevalves, thus, creating overlapping regions ofperiod of intake valve openings as well asexhaust valve openings. So VVT system

underwent design revisions to change thecam dynamically. Lobe structure is given inFigure 2.

The flank of the lobe determines the lift of thevalve i.e. height of the valve opening. Theduration of the lobe also alters the time forwhich the valve remains open. On onecamshaft rod you can have multiple lobesspaced; ECU can shift the camshaft axially toengage different lobes based on the need andfeature tuning done by the car driver.Hydraulic actuators can be used to shift thecamshaft. At higher engine speeds, most of

VVTL systems shift to higher lift and higherduration lobes. Higher lift causes more air tobe pumped into the cylinder. Engines revvingat high speeds, for example 5000 rpm, cangenerate enough air momentum to shut thevalves from inside of the cylinder. Hence,special attention has to be paid whileopening/closing of the valves.


34


37/60

Figure 2: Camshaft Lobe Cross Section (Ref. 3)

If the engine is naturally-aspirated non-turbocharged

Techtalk April June 2014 Powertrain

Documents

Transcript of Techtalk April June 2014 Powertrain