Patent ID: 6094613
Filing Date: 2000-07-25
Classification: B60W,F16H,Y02T,Y10T

Abstract:
A control apparatus for controlling a vehicle automatic transmission configured to transmit an increased or decreased engine speed outputted to a drive shaft in a vehicle and to change a transmission gear ratio, includinga plurality of friction engagement devices configured to turn on or off transmitting the outputted engine speed by engagement or disengagement of friction transmitting mechanisms,a hydraulic circuit configured to effect the vehicle speed changing with change of the transmission gear ratio by causing at least one friction transmitting mechanism of said friction engagement devices to engage and causing at least one friction transmitting mechanism of the remaining friction engagement devices to disengage, andpressure control command generator configured to generate a pressure control command value to control the hydraulic pressure to be supplied to said hydraulic circuit for effecting disengagement of the friction transmitting mechanism of said friction engagement device at the time of the vehicle speed changing, the control apparatus comprising:an acceleration detector configured to detect a longitudinal vehicle acceleration;an inertia phase detector configured to detect, in the period from the start to the end of the vehicle speed changing, an inertia phase by using a variation in the acceleration, said inertia phase following a torque phase;a torque variation calculator configured to calculate a coefficient value of the torque variation of the drive shaft from the value of the acceleration in the inertia phase;memory configured to store a predetermined constant value of the torque variation of the drive shaft in the inertia phase; anda comparator configured to compare the coefficient value of torque variation with stored constant value to determine when said friction engagement device is in a changed state over time to cause said pressure control command generator to output the pressure control command value.