CONTROL SYSTEM FOR VEHICULAR AUTOMATIC TRANSMISSION

摘要

A control system for executing an upshift from an off-going speed ratio to an on-coming speed ratio by controlling the release of the hydraulic pressure from the frictionally engaging element used for the off-going speed ratio and by controlling the supply of the hydraulic pressure to the frictionally engaging element used for the on-coming speed ratio comprises first and second off-going pressure releasing valves 70 and 80, which release the hydraulic pressure of the frictionally engaging element used for the off-going speed ratio, and a linear solenoid valve 60, which controls the operation of the off-going pressure releasing valves. The linear solenoid valve 60 controls the operation of the off-going pressure releasing valves in correspondence to the throttle opening of the engine. In this case, the smaller the throttle opening of the engine, the earlier the timing for releasing the hydraulic pressure from the frictionally engaging element used for the off-going speed ratio is set.