The Performance of One-Way Clutch in a Cam-Based Infinitely Variable Transmission

Abstract

Continuously variable transmission is the system which provides a step-less change in transmission ratio between two rotating shafts. When it can provide zero ratio, it is known as infinitely variable transmission (IVT). These systems are mainly classified into two categories; traction and non-traction types. In the traction type, the power is transmitted by friction force that develops between the active elements in the mechanism, while in the non-traction systems, the power is transmitted via direct contact. A very common type of non-traction IVT is the cam-based system. In this type, the rotating motion of the input element is converted to oscillatory motion with continuously variable amplitude. Eventually, the oscillatory motion is rectified to one-way rotational motion by means of a one-way clutch (rectifier). The rectifier is considered an essential element in the IVT system, as it is subjected to an extreme dynamical condition. In this study, the performance of one-way clutches (rectifiers) in a cam-based IVT is presented. The IVT system under consideration is a combination of two identical units and in each one, a rectifier is fitted at the output shaft. It is required that this rectifier is able to efficiently transmit the power during its engagement. It should also generate minimal power loss during disengagements, when aggressive relative motion is presented between its parts. It has been found that the operation of the one-way clutch is mainly determined by the designed cam profile. For this study, the profile is a combination of constant speed and trapezoidal forms. It was also concluded that the value of the selected transmission ratio controls the amount of fluctuation in the acceleration, velocity and displacement and hence, the energy lost due to slippage of the clutches.