Cvt Literature Review

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Trends in Continuously Variable Transmission System: A Literature Review Rushikesh Chaware1, Prof. V. H. Bansode 2 1Department of Mechanical Engineering, Smt. Kashibai Navale College of Engineering, Pune, 2Department of Mechanical Engineering, Smt. Kashibai Navale College of Engineering, Pune, ABSTRACT Ample amount of research is going on since last two decades for improving the fuel economy and reduce power loses in vehicle by developing power train systems. Continuously variable transmission (CVT) is a solution for it. The CVT gives the continuously varying gear ratio instead of discrete ratios which saves fuel and gives better performance of vehicle that complies with the engine's working…show more content…
1.(a) Principle of a V-belt CVT; (b) Variator geometry[1] 2. VARIOUS TYPES OF CVT There are many types of CVTs each with its own unique characteristics, but belt and chain CVTs have gained more importance as they were able to meet the requirements at some context. Following are some types of CVTs. 2.1. Push Belt CVT Push Belt type of CVT is the most common type. It has a belt composed of segmented steel blocks stacked on a steel ribbon as shown in Fig.3. This belt is used to transmit power between two conical pulleys or sheaves, one fixed and one moving. With this special type of belt it also uses a electronic circuit for continuously changing the distance between the pulleys depending on the engine output which is analogous to the shifting of gears. The advancement in push belt type has been rapid in few years and it has drawn more attention of automakers. Fig. 2.Model of Push Belt CVT [8] Fig. 3.Composition of Push Belt[8] 2.2. Toroidal Traction-Drive…show more content…
5. Variable Diameter Belt CVT[2] 2.4. Nutating Traction Drive CVT This type of drive uses a pivoting, conical shaft to change the gear ratios which is analogous to hanging gears in CVT. As the cone angle changes the inlet radius decreases and outlet radius increases, resulting in change in gear ratio. Thus by changing cone angle between two limits an infinite gear ratio can be obtained. 3. SINGLE ACTING PULLEY ACTUATOR CVT This is the modification in the Push Belt type of CVT here the servomotor is utilized as an actuator and a spring mechanism is also utilized. The primary pulley's movable sheave is actuated by the servomotor with gear reducer and power cam mechanism and movable sheave of secondary pulley is actuated by the spring mechanism for the clamping force, as shown in Fig.6. A spring disc is inserted in the back of the secondary pulley sheave to provide a continuous clamping force to the belt to reduce the slip during transmission. When CVT is transmitting, the change in gear ratio is required the servomotor will actuate the primary pulley in axial direction to the required value, at the same time the spring mechanism will actuate the secondary pulley to adjust the radius to required value and provide a optimal clamping force to prevent slippage. Thus the modification in CVT reduces the slip and makes it more efficient for

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