This document presents information on continuously variable transmissions (CVTs). It discusses the three main types of CVTs: pulley-based, toroidal, and hydrostatic. Recent developments in CVTs from Subaru, Honda, and Nissan are outlined, focusing on improved fuel efficiency and driving experiences. Advantages include improved fuel efficiency and engine performance, while disadvantages include higher costs and limitations for high-torque applications. Future applications in hybrid vehicles are also discussed.

1. Title:
Continuously Variable
Transmission
Presented by:
Mr. Sanket Rairker (53)
Guided by:
Prof. N. H . Khandare

2. Contents
1. Introduction
2. Types :
o Pulley based
o Toroidal
o Hydrostatic
3. Recent Developments
o Infinitely variable transmission by Subaru, Japan
o Honda CR-Z CVT
o Nissan XTRONIC
4. Advantages and Disadvantages
5. Future scope
6. Conclusion
7. References

3. Introduction
• Fuel economy dilemma solution : CVT , a type
of AT
• How is it different from conventional
transmission?
• History:-
• Birth- Leonardo da Vinci’s sketches
• GM revives it 500 years later
• DAF creates first commercially successful model
in 1958.
• Subaru and Nissan further refine it.
• Ford starts the trend for chain driven models.
• Nissan uses toroidal CVT’s

4. TYPES
1. Pulley Based CVT
• Contains :Drive pulley, driven pulley and a belt
connecting them.
• Diameter of pulleys is variable.
• Effective speed ratio maintained.

5. 2. Toroidal CVT
•Contains two discs( i /p , o/p),and two
rollers.
•Rollers maintain contact between
discs , transmit power.
•Corresponding areas of contacts of
each disc determines the speed ratio.
•Rollers are pivoted such that a large
no. of speed ratios can be obtained.
•Effective for high torque apps due to
greater durability(no belts).

6. 3. Hydrostatic CVT
•Contains a variable displacement(i/p) pump
and a hydraulic motor(o/p).
•Pump drives the motor using the fluid. Flow
of fluid varied by the pump.
•Consequently, motor speed varies, thus
varying the torque.
•Fluid circulates between the two components
continuously.
•Useful for high torque applications , but prone
to contamination.
•Costlier than other types.

7. Recent Developments
1. Infinitely variable
transmission (IVT) , by
Subaru, Japan
• An IVT is a CVT featuring a
“zero” ratio ;zero o/p for finite i/p
speed, thus ratio is ∞.
• Zero relates to idling
• Enables reversal of rotation.
• Output shaft connected to a
epicyclic gear set , which helps
shift between three modes:
forward , neutral , reverse.

8. 2. Honda CR-Z CVT
• Used in mid sized vehicles.
• Features a highly efficient oil pump containing
sintered gears for improved performance.
• G-Design Shift, a new coordinated control
system for gearing, throttle and hydraulic control,
responds quickly to driver input, maintains strong
and smooth acceleration and helps realize an
exciting and sporty driving feel.
•Also features “Idle stop” technology which
temporarily stops the engine if idling for longer.
•5 percent higher fuel economy than a
conventional CVT.

9. 3. The Nissan Xtronic :
•Ratios about 30% faster, providing
instantaneous response to the driver's
intention, in addition to a natural feeling
of poweGear ratio range from low to
high gear is expanded to approximately
6.
•Pulley and steel belt improvements and
the use of high performance ATF
(Automatic Transmission Fluid).
•Improved the electronic control system
and the hydraulic system components
that control the elements of the CVT.
•Result: Improved acceleration , fuel
economy and driving experience.

10. Advantages and Disadvantages
Advantages
• Improved fuel efficiency.
• No shift shock to the engine
as well as the driver.
• Engine runs at its most
efficient speed, virtually
independent of vehicle
speed.
• Faster acceleration and
increased driving comfort.
Disadvantages
• High cost.
• Not suitable for use in very
high torque engines.
• Design of belt and the
pulleys is difficult.
• Slippage in the drive belt or
rollers.

11. Future scope
• CVT can be improved with research on the belt design
permitting use in high performance vehicles.
• Hybrid vehicles will also feature with this type of transmission
:
• Electric motors can avoid the low speed/ high torque
problems often associated with CVTs, through an
innovative double-motor system.
• Kia recently tested a system where the CVT allows the
engine to run at constant speed and the motor allows the
engine to run at constant torque independent of driving
conditions.
• In the future a major amount of cars will feature CVT .

12. Conclusion
• The applications and benefits of continuously variable
transmissions can only increase based on today’s research and
development.
• With an increase in the number of companies opting for CVTs
there will be a consequent decrease in the cost of the vehicle as
well as the transmission.
• CVTs can as well replace the existing automatic transmissions
and thus become the most frequently used transmission
system.

13. References
• N. Srivastava, I. Haque A review on belt and chain continuously variable
transmissions (CVT): Dynamics and control, Mechanism and Machine
Theory 44 (2009) 19–41.
• Manring,Al-Ghrairi,Vermillion,2013,”Designing a hydraulic continuously
variable-transmission (CVT) for retrofitting a rear-wheel drive
automobile”, Journal of mechanical design , ASME , Volume
1.35,December 2011.
• http://www.nissanglobal.com/EN/TECHNOLOGY/OVERVIEW/cvt.html.
• "SEAT Exeo 2.0 TSI technical information". Retrieved 14 September
2009.
• "Suzuki Electrically-controlled Continuously Variable Transmission
(SECVT)". Global Communications Magazine (Suzuki Motor Corp.) 1.
2002. Retrieved 18 October 2013.
• https://www.subaru.com/engineering/transmission.html