Hydraulic control system for automatic transmission

A hydraulic control apparatus for an automatic transmission of a vehicle, the control apparatus comprising:

• an oil pump driven by an engine;
• a forward clutch arranged to be changed over from a disengagement state to an engagement state by an engagement pressure from the oil pump at a start of the vehicle;
• an idling stop control section configured to stop the engine at a stop of the vehicle when a predetermined condition is satisfied, and to restart the engine when the predetermined condition is not satisfied;
• an engine speed sensing section configured to sense an engine speed;
• a filling start judging section configured to judge a start of filling to the forward clutch when the sensed engine speed is greater than a complete explosion judging engine speed and when an integrated value of the sensed engine speed is greater than an engine complete explosion judging total rotation number;
• and
• an engagement pressure control section configured
• to control the engagement pressure to output a filling pressure command value until an end of a piston stroke of the forward clutch in a filling phase, and then to hold clutch plates in a slip state after the end of the piston stroke of the forward clutch in an engagement phase when the forward clutch is changed over from the disengagement state to the engagement state, and
• to shift from the filling phase to the engagement phase when a predetermined time elapses from the judgment of the start of the filling to the forward clutch.

A hydraulic control method for an automatic transmission of a vehicle including an oil pump driven by an engine, and a forward clutch arranged to be changed over from a disengagement state to an engagement state by an engagement pressure from the oil pump at a start of the vehicle, the control method comprising:

• stopping the engine at a stop of the vehicle when a predetermined condition is satisfied;
• restarting the engine when the predetermined condition is not satisfied;
• sensing a hydraulic pressure in the automatic transmission;
• judging a start of filling to the forward clutch in accordance with the sensed hydraulic pressure;
• and
• controlling the engagement pressure to output a filling pressure command value until an end of a piston stroke of the forward clutch in a filling phase, and then to hold clutch plates in a slip state after the end of the piston stroke of the forward clutch in an engagement phase when the forward clutch is changed over from the disengagement state to the engagement state, and
• shifting from the filling phase to the engagement phase when a predetermined time elapses from the judgment of the start of the filling to the forward clutch.