Development of a positive drive iCVT(Incremental Continuously Variable Transmission)

6th International CTI-Symposium „Innovative Automotive Transmissions“3 – 7 December 2007, Berlin, Germany

Dr. J.J. Naude, Barloworld CVT Technologies

Dr. J.J. NaudeBarloworld CVT Technologies

South Africa

1. Naudic iCVT concept

2. iCVT operation

3. iCVT ratio shifting

4. iCVT prototype

5. Different design configurations

6. On-highway commercial vehicle simulation

7. Conclusion

Presentation content

The old basis for a CVT is a chain/belt running between two movable conical sheaves, with the sheaves being movable on theiraxis, thus adjusting the radius at which the chain/belt rests with chain/belt sides in friction drive with the sheaves.

The NAUDIC iCVT transforms above old concept into a new mechanically positively linked positive drive concept which:

Eliminates the frictional and control losses

Can be scaled to meet any torque or power requirement

Allows small incremental ratio shifts without powerinterruption

1. Naudic iCVTConcept

IdlersChain throat

Partial drive

Chain with extended pins

Conical disk

Drive bars operating in slots in the conical disks

Variator2. iCVT operation

2. iCVT operation

Chain pins ONLY position chain on sheaves

Drive bars roll into position on chain rollers

Drive bars are positively locked in place by the chain links

Chain rollers Drive barChain links Chain pins

Chain

2. iCVT operationDrive bar synchronization

Video clip of drive bar synchronization in the chain throat

2. iCVT operation

Throat Idler

Model in low ratio

Throat Idler

Chain throat

Slack idler

Input driver

Input driver

2. iCVT operation

Throat Idler

Model in high ratio

Throat Idler

Chain throat

Slack idler

Input driver

Input driver

2. iCVT operation

iCVT input

Input drive

Slack idler tensioning system

Sprag incorporated input driver

Sprag incorporated input driver

3. iCVT ratio shiftingGeneva wheel based

Based on the proven Geneva indexing wheel

Accurate and synchronized mechanical shifting

Simple and robust design for generation of high speed and high torque shifting.

Simple solenoid activation of a pure mechanical shifting sequence

iCVT shifting requiresan index on demand in both directions mechanical device

Geneva wheel

Geneva drivers

Animation3. iCVT ratio shifting

Model shifting3. iCVT ratio shifting

Geneva wheel is actuated by a barrel cam

Barrel cam is activated by a solenoid pin

Barrel cam

Solenoid pin

iCVT shifter as implemented in the iCVT model

Very similar to iCVT shifter implemented in the iCVT test vehicle

Geneva driverGeneva

driver

4. iCVT prototypeVehicle

Controlling PC in cockpit of test vehicle

iCVT prototype fitter to the rear of the test vehicle

Drive train configuration4. iCVT prototype

Variator4. iCVT prototype

Metal band chains proven in commercial friction drive CVT’s

Every second link adapted for positive drive in ribbed sheaves

Very small pitch – typically 4mm

Very small ratio increments

Composite metal bands

Driver links in blue and Spacer links in orange

Commercial friction drive band chain

5. Design configurationsComposite metal band chain

Alternating drive links positively engage driver cavities and sheave ribs

Driver cavity

Driver links in blue

Sheave

Ribs

5. Design configurationsComposite metal band chain

Rocker pin chains proven in commercial friction drive CVT’s

Rocker pin tips profiled to engage sheave ribs

Rocker pins provide robust and silent drive

Composite metal bands

Commercial friction drive

rocker pin chain

Rocker pin chain5. Design configurations

Alternative rocker pin ends, positively engage driver cavities and sheave ribs

Driver cavity

Driving rocker pin

ends

Sheave

Ribs

5. Design configurationsRocker pin chain

All simulations were done on a software package, VBDrive, originally developed for the South African

military

6. SimulationsVBDrive

Input data to the simulations included:

Engine fuel consumption and performance data

GPS plotted routes

Other vehicle and drive train specifications

Current VBDrive users include:

Simulation highlights - fully laden (8 ton) truck

13.59% fuel consumption reduction on highway conditions (speed limit 120 km/h)

14.3 % reduction in acceleration time 0-80km/h

8 ton commercial truck6. Simulations

7. Conclusion

iCVT concept provides CVT capability

Mechanical efficiency comparable to manual transmissions

iCVT concept can be scaled up to accommodate any power or torque range

iCVT concept proven in iCVT test vehicle and can be test driven by interested parties.

iCVT CONSEPT is patented in 13 countries based on WO2005/036028

Contact:Richard S. Michelson

Barloworld CVT Technologies

180 Katherine Street Sandton

P.O. Box 44947 Linden 2104 South Africa

Tel +27 11 887 0825

Fax +27 11 786 4159

Cell +27 82 093 4449

E-mail rmichelson@barloworld-cvt.com

Web www.barloworld-cvt.com

Contact details