| 摘要 |
PROBLEM TO BE SOLVED: To prevent a uncomfortable speed change feeling at the time of extremely low oil temperature by forbidding a speed change operation toward a low speed stage until a prescribed time has elapsed after the speed change operation toward a high speed stage was completed, when the discharging state of the hydraulic pressure is delayed more than a prescribed time from a frictional engagement element on the side on which the element is released at the time of a speed change. SOLUTION: When a speed change from a first speed stage to a second speed stage is to be achieved, first and second brake solenoid valves 35, 32 are put under the duty control of a controller 37, and by supplying the line pressure adjusted to a prescribed pressure to first and second brake servos 34, 31, the operation of first and second brakes 11, 12 can be controlled. At this time, if a down-shift to the first speed stage is performed at a very low temperature (e.g. oil temperature of -15 deg.C and below), the hydraulic pressure is supplied again before the discharge of the hydraulic pressure from the second brake 12 is thoroughly completed, because of the high viscosity of the oil or a delay of the motion of the second brake 12, resulting in excessive supply of the hydraulic pressure. To prevent this, the down-shift is forbidden for, for example, two seconds. |
