Patent ID: 6887183

Claim:
A system, comprising: an automatic transmission which achieves a first speed by engagement of a first engaging element and a second speed by engagement of a second engaging element; a device which generates a torque signal corresponding to input torque to the automatic transmission; and an electronic control unit (ECU) which controls the automatic transmission with reference to a shift line of a throttle opening versus a vehicle speed, the ECU being programmed to: determine shift from the second speed to the first speed when the throttle opening crosses the shift line; carry out changeover control in accordance with the determined shift to achieve release of the second engaging element and engagement of the first engaging element; detect a magnitude of the torque signal before a predetermined time of the determined shift when the changeover control is carried out; compare the magnitude of the torque signal with a preprogrammed switch determination value; carry out a first control of the second engaging element when the magnitude of the torque signal is larger than the preprogrammed switch determination value; carry out a second control of the second engaging element when the magnitude of the torque signal is equal to or smaller than the preprogrammed switch determination value, the second control requiring shorter time than the first control; and control the release of the second engaging element in accordance with one of the first and second controls.