Patent ID: 6843754

Claim:
A control apparatus for controlling an automatic transmission for a vehicle comprising: an automatic transmission capable of switching plural shift stages; a torque converter for controlling transmitting rotation of an engine to the automatic transmission via a fluid; a first friction engagement element for connecting a turbine wheel housed in the torque converter and a forward movement member housed in the automatic transmission when the first friction engagement element is engaged; a one-way clutch housed in the automatic transmission to establish a predetermined shift stage in the automatic transmission cooperating with the first friction engagement element; and a second friction engagement element housed in the automatic transmission to prevent an output shaft of the automatic transmission from being rotated in a reverse direction cooperating with the one-way clutch when the second friction engagement element is engaged, wherein an engagement force for engaging the first friction engagement element is set to be lower than an engagement force for establishing the predetermined shift stage with the second friction engagement element being engaged when a vehicle is under a stationary condition with an acceleration operating member not being operated and a brake operating member being operated under a forward driving range being established in the automatic transmission, the engagement force for engaging the first friction engagement element is increased when the vehicle starts from the stationary condition with the brake operating member released from the operated condition, and the engagement force for engaging the second friction engagement element is decreased when a relative rotational speed between the turbine wheel and the forward movement member becomes equal to or smaller than a predetermined rotational speed, thereby the predetermined shift stage is established in the automatic transmission; and wherein the engagement force for engaging the second friction engagement element is decreased at a predetermined rate when the relative rotational speed becomes equal to or smaller than an intermediate rotational speed which is greater than the predetermined rotational speed in response to the vehicle start from the stationary condition with the brake operating member released from the operated condition, and the engaging force for engaging the second friction engagement element is further decreased faster than the predetermined rate when the relative rotational speed becomes equal to or smaller than the predetermined rotational speed.