Continuously variable transmission

Presenter : Junaid ahmed (Ned UNIVERSITY) AUTOMOTIVE ENGINEERING 09-10

CONTINUOUSLY VARIABLE

TRANSMISSION (CVT)

A Continuously variable transmission (CVT) is a transmission which can change steplessly through an infinite number of effective gear ratios between maximum and minimum values.

Continuously Variable Transmission

Types of CVT CVT has been classified into Seven(10)

types:1.  Pulley Based CVT’S or Reeves drive2. Toroidal or roller-based CVT (Extroid CVT)3. Magnetic CVT or mCVT4.  Infinitely Variable Transmission (IVT)5.  Ratcheting CVT6.  Hydrostatic CVTs7.  Naudic Incremental CVT (iCVT)8.  Cone CVTs9.  Radial roller CVT10.  Planetary CVT

Pulley Based CVT’S

o In this most common CVT system , there are two V-belt pulleys that are split perpendicular to their axes of rotation, with a V-belt running between them.

Toroidal CVT’S

o Toroidal CVTs are made up of discs and rollers that transmit power between the discs.

Hydrostatic CVT’S

o Hydrostatic transmissions use a variable displacement pump and a hydraulic motor. All power is transmitted by hydraulic fluid.

Infinitely Variable Transmission (IVT)o A subset of CVT designs are called infinitely variable transmissions (IVT or IVTs)

Cone CVTs

o A cone CVT varies the effective gear ratio using one or more conical rollers.

WHY Use CVT……..?

CVT MT8.8 sec. 11.9 sec.

0-100 Km/h

• The Continuously Variable Transmission (CVT) proved 35% more efficient than the Manual Transmission (MT).

• With same car and engine, the CVT takes only 75% of the time to accelerate to 100km/h, compared to the MT.

Disadvantages of Gearbox

Produce jerk to vehicle during the change of gears.

Considerable loss of power in the transmission system.

Low starting acceleration.

Considerable driving fatigue

Advantages of CVT Constant, stepless

acceleration.

The main advantage of CVTs is that they allow an engine to run at its ideal RPM regardless of the speed of the vehicle.

There are 25% fewer moving parts to a CVT transmission.

There are 25% fewer moving parts to a CVT transmission.

Less power loss in a CVT than a typical automatic transmission.

Responds better to changing conditions, such as changes in throttle and speed.

APPLICATIONS Many small tractors for home and garden use simple rubber belt CVTs.

All snowmobiles, old and new, and motor scooters use CVTs.

Audi A4 also uses CVT.

CVTs have been used in aircraft electrical power generating systems and in Formula race cars.

Future Of CVT

Fuel economy and Emissions New fuel regulations. Cost

CONCLUSION CVT is the most superior technology for power transmission And it would be the widely acceptable technology throughout the world.

REFERENCES www.Howstuffworks.com

www.Wikipedia.org

www.nissan-global.com

www.autos.aol.com

THANK YOU