Patent ID: 6962547

Claim:
An oil pressure control device for use with a vehicle transmission, which transmission has a shift lever that is configured to select a range from among a drive range that advances the vehicle, a reverse range that reverses the vehicle, and a stop range that stops the vehicle, wherein the vehicle has forward and reverse frictional-engagement devices that convert a drive force generated by an engine to a drive force that advances the vehicle or a drive force that reverses the vehicle, wherein the forward frictional-engagement device is engaged by oil pressure in the drive range, wherein the reverse frictional-engagement device is engaged by oil pressure in the reverse range, and wherein both the forward frictional-engagement device and the reverse frictional-engagement device are released in the stop range, the oil pressure control device comprising: a pressure adjusting device that engages or releases the forward frictional-engagement device or the reverse frictional-engagement device by supplying the oil pressure to one of the forward frictional-engagement device and the reverse frictional-engagement device; a sensor that detects a range selected by the shift lever; and a controller that controls the pressure adjusting device based on a signal from the sensor, wherein the controller is configured to measure a stop-range selected time period during which the stop range is selected after the reverse range, and wherein the controller functions to control the pressure adjusting device to: supply an initial oil pressure to the forward frictional-engagement device and subsequently decrease the supplied oil pressure from the initial oil pressure to a predetermined oil pressure, when the drive range is selected after the stop range or the reverse range; increase the supplied oil pressure at a small increase rate from the predetermined oil pressure during a predetermined time period; and increase the supplied oil pressure at a large increase rate, after the predetermined time period has elapsed, wherein, during the predetermined time period, the supplied oil pressure is set depending on the stop-range selected time period.