METHOD OF CONTROLLING SPEED SHIFTING OPERATION OF AUTOMATIC TRANSMISSION

摘要

PURPOSE:To prevent the fluctuation in the acceleration of a vehicle body and its vibration at the time of speed shifting, by changing the engaged state of frictionally engaged elements of a gear mechanism at the time of speed shifting while keeping a high gear clutch unengaged. CONSTITUTION:While the speed of a vehicle is not lower than a prescribed level, a high gear clutch 7 is kept engaged, by a solenoid valve 42. When a speed shifting signal is generated at the time t1 during that period, the high gear clutch 7 is immediately disengaged and timers (a), (b) start operating. The operation time of the timer (a) is set shorter than that of the other timer (b). At the time t2 when the operation of the timer (a) ends, a low-second and a second-third solenoid valves 40, 41 act to change over the engaged state of engaged elements. At the later time t3 when the operation of the timer (b) ends, the solenoid valve 42 acts to keep the high gear clutch 7 again engaged from the time t3 on.