Hydraulic pressure control system for hydraulically operated vehicle transmission

摘要

A vehicle automatic transmission control system, in which when a gear to be shifted to is determined in response to the throttle opening and vehicle speed, hydraulic oil is supplied to a clutch for the gear to be shifted to. In an early period of the gearshift, the hydraulic oil is supplied to decrease a time lag between an output of the gearshift command and a start of clutch engagement. In the system, there is provided, instead of an expensive oil pressure sensor, a means for estimating or detecting the clutch oil pressure as an capacity of power which the clutch can transmit. When the estimated or detected pressure is high, the supply of oil to the clutch is prohibited so as to prevent sudden clutch engagement which would otherwise produce shock.