Capacity control for nested clutch automatic transmission

摘要

A method and apparatus for increased clutch capacity in an automatic vehicle transmission having a nested clutch pair. An electronic control unit controls a pulse width modulator which applies control signals to the actuating solenoid valves of the nested pair of clutches. The electronic control unit operates to reduce the pressure on an engaged clutch of the pair during the period of time that the other clutch is being actuated during the shift. Once the shift is completed, the operating pressure on the previously engaged clutch is restored to a normal operating pressure. Provisions are also made for assuring that the period of time required for the shift is maintained between threshold limits or within a window of time. This adaptive feature precludes excessively short or long shifts.