Control system and method for controllable output type hydraulic fluid pump of automatic transmission providing decreased pump output in association with the engine starting condition

摘要

An automatic transmission, for a vehicle with an engine, includes a hydraulic fluid pump which supplies pressurized hydraulic fluid. It is detected whether or not the engine is being started, and the pump output is controlled so as to be decreased when the engine is being started. If the pump is one whose output per one revolution of its input member is variable, then its output may be thus controlled by decreasing its output per one revolution when the engine is being started. And, if the pump is a variable capacity type vane type hydraulic fluid pump the output of which per one revolution of its input member is controlled by varying the eccentric position of a controlling member thereof, then its output per one revolution may be thus controlled by varying this eccentric position to give a pump output per one revolution decreased when the engine is being started. Alternatively, if the pump is a fixed capacity type electrically driven type hydraulic fluid pump the output of which per one revolution of its input member is substantially constant, then its output may be thus controlled by decreasing the rotation speed of its input member, possibly to zero, when the engine is being started. A system for implementing this method is also disclosed.