Technology for Prediction of Torque Capacity during Operation of AT with Focus on Friction Properties of Facing Materials in Multiple Plate Clutches

The project discussed in this paper focused on the torque transmission characteristics of facing materials in order to enable desktop prediction of the torque capacity of the multiple plate clutches used in automatic transmissions (AT). The amount of torque transmitted by the facing materials themselves is affected by the temperature, contact pressure and sliding velocity of the friction surfaces. An analytic model of a test apparatus was therefore constructed, and the friction properties of the facing material were identified from the amount of torque transmitted. Next, a torque capacity prediction model, able to simulate the flow of torque transmission in the transmission, was constructed. This enabled torque capacity in an operating AT to be predicted for the first time with an accuracy to within ±5% of measured values. In addition, an examination of the friction force vectors of the clutch disks showed that torque capacity is affected not only by friction force components acting in the direction of rotation, but also by simultaneously produced friction force components acting in a radial direction. The project also showed that the developed method of predicting torque capacity is effective for ATs with differing clutch layouts.