technique on developin a VCR Engine

1. KISHORE THATIKONDA

2. What is Compression Ratio?
If compression ratio becomes large,
then thermal efficiency increases,
But, engine power decreases due to Knocking

3. Solution for the Contradiction
 Low Load & Speed : High C/R - Engine Efficiency ↑
 High Load & Speed : Low C/R - Engine Power ↑

4. What is VCR Engine?
 Variable Compression Ratio(VCR) Engine, where the
compression ratio of the engine can be controlled at
each operating condition

5. Why VCR ?!
 Down sizing the engines
 Increasing the fuel efficiency
 Obtain more engine power with less amount of fuel
 VCR + Turbo Engine improves 20~30% of Fuel
Consumption in comparison with the same power of
Engine

6. Chart – Engine Efficiency vs Engine
Power

7. Objectives
 To learn the existing techniques in VCR Engine
 To come up with a better technique
 To build a model in SolidWorks
 To simulate the model
 To analyse the pressure inside the chamber

8. Existing Techniques

9. Moving Cylinder Head - SAAB

10. Moving Cylinder Head Type

11. Varying Combustion Chamber
Volume - Ford

12. Modification of Connecting Rod
Geometry - Nissan

13. Modification of Connecting Rod
Geometry - Nissan

14. Control Shaft Movement

15. Crank Pin Alteration - Rapan

16. Crank Pin Alteration - Mayflower

17. Modification of Connecting Rod
geometry - Peuguot

18. Techniques at a Glance

19. Suggestions
 By combining the SAAB’s moving head technique and
the Ford’s additional piston technique
 Combustion Chamber Volume can be easily varied using
an additional piston
 Moving head- instead to move the head, the piston can
be moved so that more volume is created in the chamber
with a little displacement of the piston

20. Idea 1

21. Idea 1 details
 Using a rack and lead screw type of arrangement on
either side of the additional piston
 With the movement in the lead screw piston can be
moved
 Advantages
 More cylinder volume is created with a small movement of the
piston
 Disadvantages
 Placing the sparkplug
 Due to the high pressure, rack and lead screw arrangement
may fail

22. Idea 2
 By using control slot, the piston can be moved

23.  The movement of the slot can be controlled using a
hydraulic pump

24.  By using this method the VCR can be obtained
 Spark plug is fixed in the additional piston which has a
hemispherical shaped crown
 This shape will be helpful in spark development
 And also to obtain more volume when compared to the
flat surfaced piston

25. Variable Displacement using
Control Slot

26. Result of Idea Generation

27. Future Works
 Pressure inside the combustion chamber for various
compression ratios is derived
 Analysis on the additional piston with the peak
pressure to check the factor of safety and running
conditions

28. Conclusion
 Variable Compression Ratio engine can maximize the
engine power and fuel economy
 Several concepts of VCR engine are obtained
 A new concept of VCR Engine is developed