Abstract
The project discussed in this paper focused on the frictional characteristics of clutch facing materials in order to elucidate the mechanism by which the torque capacity of the multiple plate clutches used in automatic transmissions (AT) varies with mode of use. The frictional characteristics of the facing materials are affected by the temperature, contact pressure, and sliding velocity of the friction surfaces. The temperature of the clutch plate, sliding velocity of the friction surfaces, and degree of misalignment of the gears transmitting torque were therefore measured in an AT during torque transmission. Next, a torque capacity prediction model, able to simulate the flow of torque transmission in the AT, was constructed on the basis of these measurement results. An examination of the friction force vectors of the clutch disks showed that the torque capacity of an AT operating at a constant temperature is affected by radial components of the friction force vectors on the friction surfaces. In addition, this model enable torque capacity in an operating AT to be predicted for the first time with an accuracy to within ±5% of measured values.
