Clutch assembly for semiautomatic gear transmission

Abstract

A disk clutch inserted between a torque converter and a synchromesh gear train of an automotive transmission comprises a driving friction-plate carrier coupled with the turbine of the converter and a driven friction-plate carrier coupled with an input shaft of the gear train, the driving carrier forming two fluidically separated concentric cylinder spaces between itself and an operating piston embraced thereby. The inner cylinder is of smaller effective area and is pressurized in normal operation by hydraulic fluid (oil) but can be temporarily depressurized, during gear shifting, by a valve controlled by the shifting mechanism; this space communicates via an internal flow channel of the driving carrier with a radial bore in that carrier occupied by a centrifugally and/or resiliently loaded body of a quick-venting valve normally blocking an exit port leading from the outer cylinder space to the interior of a surrounding housing. Upon the unblocking of that exit port in response to depressurization of the inner cylinder space, the piston is moved by a Belleville spring into a disengagement position until the inner cylinder space is repressurized whereupon fluid from that space re-enters the internal flow channel and represses the quick-venting valve to this blocking position while also passing through the valve body into the outer cylinder space to help return the piston to its engagement position.