Time-varying friction thermal characteristics research on a dry clutch

Abstract

In the continuous shifting condition, frequent working on a dry clutch causes a sharp internal temperature rise on the friction surfaces of the clutch. In order to determine the force on the friction surfaces of the clutch accurately, the elastic characteristics produced by the cushion spring, the link strip and the diaphragm spring are analysed in this paper. Then, through monitoring of the throw-out bearing force, the friction torque of the clutch and the slipping-friction power can be estimated. Finally, based on three thermal loads on the friction surfaces of the dry clutch (including the initial environment temperature, the slipping-friction power and the convection heat), its thermal field distribution with changes in the time and the radius during the entire shift process can be acquired. In the earlier phase (before approximately 180 s), the surface temperature distribution varies with the slipping-friction power. Also the slipping-friction power plays a major role in the thermal load on the friction surfaces. However, the slipping-friction power does not do so in the later phase (after about 180 s) owing to the difficulty with heat radiation. This means that the time-varying thermal characteristics of a dry clutch are related to the working time of the clutch.