A Seminar on

Continuously Variable Transmission

Presented byBagwan Nadim M.

Under guidance of Prof. S. T. Satpute

Introduction History of CVT CVT Introduction Case study: Belt type CVT Efficiency and losses Efficiency improvement strategies CVT v/s manual transmission Advantages and disadvantages of CVT Conclusion References

Content

Transmission overview(definition, necessity, functions, trends)

Types of transmission1. Manual Transmission2. Automatic Transmission3. Continuously Variable

Transmission

Introduction

First concept by Leonardo Da Vinci in 1490 Firs CVT application in 1923 by British Clyno

Car In 1926, George Cinstantinesco built car

with 2 cylinder engine Late 50’s, Hub Van Doorne built CVT called

variomatic 1965, Wheel Horse Inc., introduced

hydraulic CVT (model- 875 and 1075)

History of CVT

1974, Rubber belt CVT by Roxon 1987, electronic CVT by Subaru Late 90’s, Ford Escort and Orion models

launched with CVT 2006, Nissan with X-tronic CVT 2007, Dodge Caliber was launched 2008, Mitsubishi Lancer 2010, Suzuki SX4 and Kizashi 2013-15, Honda Accord (LX and EX)

History (contd.)

Basic concept Types of CVT 1. Variable diameter pulleys

2. Toroidal / Roller type CVT 3. Magnetic CVT 4. Infinitely Variable

Transmission 5. Ratcheting CVT 6. Hydrostatic CVT

CVT- Introduction

Elements of belt type CVT Intermediate elements:

1. metallic belt2. CVT chain3. LuK chain4. involute chain

Case Study: Belt type CVT

Belt type CVT:

Fig: Belt type CVT with low ratio

Case Study: Belt type CVT

Fig. for medium and high gear ratio: (a) medium ratio (b) high ratio

Belt type CVT (contd.)

Efficiency of CVT Losses in CVT:

1. Loss due to slip2. Pump loss3. The belt-related torque loss

Efficiency and losses

Variator Losses Improvement:1. CVT chain or intermediate

element2. Reducing of the clamping

forces Hydraulic Losses Improvement

Efficiency Improvement Strategies

Size and weight Gear ratios Manufacturing Fuel consumption Acceleration Emission control Power deliverd

CVT v/s Manual Transmission

Better fuel consumption Improved acceleration To allow the engine to revolute almost

immediately which delivers maximum torque Smoother ride experience Adapt the varying road conditions and power

demands Better emission control Lighter and smaller in size and cheaper than

any type of transmission

Advantages of CVT

Not faster and reliable Can not cope with big engines or higher

torque loads Higher cost of maintenance Limited amount of torque Transmission motion by friction causes

greater wear

Disadvantages of CVT

Continuous variable transmission (CVT) is the emerging technology in the automobile sector. The use of CVT is much beneficial compared to manual transmission and even automatic transmission. Today, emission control and the fuel economy are considered as the key requirements of the automobile manufacturing. If cost, fuel economy, emissions are considered as the prime factors, one should select CVT as the transmission system. Even there are some limiting factors of CVT, the technology is continuously improving. The limitations will soon be eliminated and the CVT will come as the standard transmission system which will also be implemented in automatic transmissions. CVT has to be seen as the future of the transmission system.

Conclusion

Tsutomu Tashiro, Noboru Miyamoto, “CVT Gear Ratio Control as an Engine Braking Actuator for Vehicle Automatic Deceleration”, Proceedings of the European Control Conference, August 23–26, 2009.

Huiwu Wang, Junting Sun, Chunguo Zhou and Hongjiang Wang, “The Research on Transmission Performances of Mechanical CVT with Friction Heat”,

E. Maleki Pour and S. Golabi, “Design of Continuously Variable Transmission (CVT) with Metal Pushing Belt and Variable Pulleys”, International Journal of Automotive Engineering, Vol. 4, Number 2, June 2014.

Carter, Jeremy, McDaniel, Loren and Vasiliotis, Christopher, “Use of a Continuously Variable Transmission to Optimize Performance and Efficiency of Two-Wheeled Light Electric Vehicles (LEV)”, EET-2007 European Ele-Drive Conference Brussels, 2007.

References

Ataur Rahman, Sazzad Bin Sharif, AKM Mohiuddin, Mahbubur Rashid and Altab Hossain, “Energy efficient electromagnetic actuated CVT system”, Journal of Mechanical Science and Technology, vol. 28 (4), pp. 1153~1160, 2014.

Talchol Kim and Hyunsoo Kim, “Integrated Engine-CV'T control Considering Powertrain Response Lag in Acceleration”, KSME International Journal,Vol. 14,No.7, pp. 764-772, 2000.

Heera Lee and Hyunsoo Kim, “CVT Ratio Control for Improvement of Fuel Economy by Considering Powertrain Response Lag”, KSME International Journal Vol 17 No. 11, pp. 1725~1731, 2003.

C. H. ZHENG, W. S. LIM and S. W. CHA, “Performance optimization of CVT for two wheeled vehicles”, International Journal of Automotive Technology, Vol. 12, No. 3, pp. 461-468, 2011.

W. Ryu and H. Kim, “CVT ratio control with consideration CVT system loss”, International Journal of Automotive Technology, Vol. 9, No. 4, pp. 459−465, 2008.

References (contd.)

L. Guzzella and A. Schmid, “Control of SI-Engines with CVT’s - A Feedback Linearization Approach”, IEEE, 7803-1872, pp. 633-638, 1994.

M. Pasquier, “Continuously Variable Transmission Modifications and Control for a Diesel Hybrid Electric Powertrain”, SAE International, 2004.

F. Xie, J. Wang and Y. Wang, “Study on CVT Ratio Tracking Controller”, Procedia Engineering, vol. 16, pp. 723 – 728, 2011.

D. C. Foley, N. Sadegh, E. J. Barth and G. J. Vachtsevanos, “Model Identification and Backstepping Control of a Continuously Variable Transmission System”, Proceedings of the American Control Conference, 0-7803-6495, pp. 4591-4596, 2001.

Talchol Kim and Hyunsoo Kim, “Low Level Control of Metal Belt CVT Considering Shift Dynamics and Ratio Valve On-Off Characteristics”, KSME International Journal, Vol.14, No.6. pp. 645-654, 2000.

References (contd.)