CONTINUOUSLY VARIABLE

TRANSMISSION

(CVT)

CONTENTS

• INTRODUCTION

• HISTORY

• TYPES OF CVT

• ADVANTAGES

• CVT VS AT

• DISADVANTAGES

• APPLICATION

• CONCLUSION

• REFERENCE

INTRODUCTION

CVT is an advanced technology of automatic transmission.

Unlike traditional automatic transmissions, continuously variable transmissions don't have a gearbox with a set number of gears.

CVT also known as single-speed transmission, gearless transmission, one-speed automatic, variable pulley transmission.

Varies the transmission ratio continuously.

Shifts automatically with an infinite number of ratios.

HISTORY

• Leonardo da Vinci sketches is the basis for the first

continuously variable transmission in 1490.

• First patent for the CVT Transmission was made by Daimler &

Benz in 1886.

• The first workable belt driven CVT was designed and built by

the Dutchman Huub van Doorne in 1958.

• In Early 1990's Nissan introduced CVT in their Nissan March

TYPES OF CVT

1. Pulley based CVT

2. Cone CVT

3. Toroidal CVT

4. Hydraulic CVT

PULLEY BASED CVT

• It consist of main 3 parts

1.Primary clutch

2.Secondary clutch

3.Belt

1. PULLEY BASED CVT

• Low Gear • Top Gear

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.

CVT belts

• https://www.youtube.com/watch?v=dp8lHBDFhpo

2. CONE CVT

CONE CVT

Fig 1.4a: Cone CVT showing the initial position of the belt as it

grips the driver shaft (lower) and the driven shaft (upper).

Fig 1.4b: Cone CVT showing the intermediate position as the belt

moves to the right with increase in rpm on the driver shaft.

Fig 1.4c: Cone CVT showing the final position of the belt as it has

moved to the end on right due to increase in rpm on the driver shaft

3. TOROIDAL CVT

• Toroidal CVTs are made up of discs and rollers that transmit

power between the discs by means of tractive force.

• A viscous fluid(EHL) is placed between the rollers and discs.

• The change in angle by a roller must be mirrored by the

opposing roller.

• The position of the rollers is controlled hydraulically.

TOROIDAL CVT

4. HYDRAULIC CVT

• It consist of variable-displacement pumps and hydraulic motor.

• In this type of transmission, the rotational motion of the engine

operates a variable-displacement pumps on the driving side.

• The pump converts rotational motion into fluid flow.

• A hydraulic motor located on the driven side, the fluid flow is

converted back into rotational motion.

HYDROSTATIC CVT

ADVANTAGES

• Allow for an infinite number of gear ratios.

• Eliminates "shift shock" -- makes it smoother ride

• Responds better to changing conditions.

• Better fuel economy & power loss than automatic transmission

ADVANTAGES

• 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 fewer moving parts to a CVT transmission.

DISADVANTAGES

• Limited torque capacity as compared to the manual

transmission system

• More costlier than manual transmission

• Slipping in the drive belt or pulleys.

• Additional gear train required for reverse condition.

APPLICATIONS

• Commonly used in automobiles

• New continuous variable transmission for medium duty trucks

and buses.

• Starts development on wind turbine cvt

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.

REFERENCE

• Nilabh Srivastava, Imtiaz Haque, “A review on belt and chain continuously

variable transmissions (CVT): Dynamics and control” ,Mechanism and

Machine Theory, Volume 44, Issue 1, January 2009, Pages 19-41.

• Mr. Jadhav S. S Prof. Hanamapure N. S, “ Toroidal Drive System for

Vehicle Transmission Control”, IJSRD - International Journal for Scientific

Research & Development| Vol. 2, Issue 09, 2014 | ISSN (online): 2321-0613.

• Da Wen Ge, Sugeng Ariyono and Daw Thet Thet Mon, “ A REVIEW ON

CONTINUOUSLY VARIABLE TRANSMISSIONS CONTROL”, National

Conference in Mechanical Engineering Research and Postgraduate Students

(1st NCMER 2010) 26-27 MAY 2010

THANK YOU…