Gear thrust controlled multi-mode clutch for power transmissions

Abstract

Multi-mode friction clutch having a plurality of interleaved clutch plates operable for establishing gear ratios in planetary and countershaft type automatic transmissions and operative to provide smooth and self-synchronized shifting without the use of one-way roller or sprag clutches. Gear thrust forces from associated helical gearing and opposing hydraulic pressure forces are used to regulate the hydraulic pressure of a piston chamber by shifting an annular control sleeve which controls fluid exhaust from the chamber to maintain a direct relationship between the torque capacity of the clutch and the variable torque it actually carries. Consequently, the clutch is automatically released when the transmitted torque diminishes to zero or reverses. The clutch is applied in a normal lock mode for predetermined gear ratios, set in one-way mode for shifting and totally released when the shift is completed. The multi-mode clutch is applicable to a chain driven multi-axis countershaft transmission construction, which further foreshortens the transmission for improved utilization of the space allocated for vehicle powertrains.