| 摘要 |
PURPOSE:To carry out down shift operation of clutch to clutch without causing gear change shock with a small time lug by maintaining oil pressure in the abrasion engaging device of an engaging side to a prescribed value in low pressure before input rotary speed of a transmission exceeds the synchronous point of a gear change step, and then boosting oil pressure thereof. CONSTITUTION:In the automatic transmission 2 of forward 5 steps and backward 1 step provided with a torque converter 111, a plural gear change part 112 and a main gear change part 113, transmission between a second speed step and a third speed step is set as clutch to clutch transmission of brakes B2 and B3, and each clutch and brake are engaged and disengaged through an oil pressure control device 20 by command of a computer 30. In this case, at the time of down shift of clutch to clutch, engaging pressure of the abrasion engaging device of an engaging side is maintained to a prescribed low pressure value after input rotary speed of a transmission exceeds the synchronous point of a gear change step, so that opening pressure in the abrasion engaging device of an opening side is maintained to a high pressure value. When input rotary speed of the transmission exceed the synchronous point of the gear change step, opening pressure is reduced while raising engaging pressure. |
