Control system for automatic transmission with servo fill of second shift engagement element during completion of first shift when second shift commanded during first shift

摘要

If a shift to the 3rd speed is decided during the 5th-4th speed shift, in which the hydraulic servo for a second clutch is released by pressure regulation control, a changeover valve is switched by a solenoid valve so that the fluid pressure PC2 from the pressure regulating valve is conducted to a third clutch hydraulic servo. Thereby, the third clutch hydraulic servo pressure PC3 stands by at a predetermined engaging pressure PH and, at the same time, the servo-start of a fourth brake fluid pressure PB4 is performed by another pressure regulating valve. Meanwhile, the fluid pressure PC2 is released by an accumulator. After the servo-start ends and the 4th speed is established, the 4-3 speed shift control is performed, thus preventing shift shock and reducing shift duration.