Control system for automatic transmission

摘要

A control system for an automatic transmission having a hydraulic power transmission for transmitting the rotation of an engine to a gear shifter; a clutch to be applied, when a forward drive range is selected, for connecting the hydraulic power transmission and the gear shifter to one another; a one-way clutch to be locked, when the clutch is applied, for establishing a first forward speed of the gear shifter; a brake for locking the one-way clutch, when applied, to block the backward rotation of the output shaft of the gear shifter; a first hydraulic servo for applying the clutch when fed with an oil pressure; a second hydraulic servo for applying the brake when fed with an oil pressure; a stopping state detector that detects the stopping state of a vehicle by determining the vehicle speed is substantially 0, the accelerator pedal is in a released state and the foot brake pedal is depressed; a gradient detector that detects the gradient load of an uphill, as applied to the vehicle; and a controller that controls the oil pressure to be fed to the first and second hydraulic servos on the basis of the signals from the stopping state detector and the gradient detector. The controller includes a decision maker that determines whether the road is uphill, on the basis of the signal from the gradient detector; a pressure reducing device that reduces the oil pressure to be fed to the first hydraulic servo, to bring the clutch into a substantially released state; a feed device that feeds an oil pressure, as regulated on the basis of the gradient detector, to the second hydraulic servo, to apply the brake at an engaging extent according to the gradient load; and a device for executing the reduction of the feed oil pressure to the first hydraulic servo by the pressure reducer and the feed of the regulated oil pressure to the second hydraulic servo by the oil pressure feeder, if it is detected by the stopping state detector that the vehicle is in the stopping state and if it is determined by the decision maker that the road is uphill.