Shift control system of an automatic transmission

摘要

A shift control system of an automatic transmission controls operating forces on frictional engaging elements being engaged and disengaged with gear elements during a shift operation by generating a target transmission variable which prevents a rate of change of a corresponding target input rotational speed from inverting at the start of the shift operation and/or at the end of the shift operation. The target transmission variable may be the target input rotational speed, a target gear ratio, or other variable corresponding to a target input rotational speed which has a rate of change gradually changing at the start and end of the shift operation so as to avoid any inversion of the rate of change within a predetermined duration after the start of the shift operation and within a predetermined duration before the end of the shift operation. The target transmission variable is applied along with a detected actual transmission variable to a feedback control which produces a signal for correcting a control hydraulic pattern produced in shift logic to operate a current control which controls a linear solenoid valve operating hydraulic servos to control the frictional engaging elements.