MULTIPLE ENGAGEMENT WET CLUTCH HEAT TRANSFER MODEL

Abstract

To optimize the thermal performance of transmission wet clutches during multiple engagements, a general thermal numerical model has been developed. At every cycle, temperatures are computed throughout the clutch materials until a periodic steady state is achieved. One cycle is characterized by (a) an engagement period where the separator plate is contacting the friction lining with heat being generated while some cooling is provided by the oil passing through friction material grooves; (b) a locked stage of separator plate and friction lining contact during which the heat generation is zero while oil cooling through the grooves continues; and (c) a cooling period with the separator plate completely disengaged from the friction lining while the oil cools both surfaces. Temperatures are calculated from the transient numerical solution of the heat conduction equation in two dimensions. The finite difference technique based on an implicit numerical scheme is employed. This approach is verified by comparison with a known solution as well as experimental data, and a sample run is presented for conditions representative of an actual clutch assembly.