Control system for hybrid vehicle

A system for controlling a hybrid vehicle equipped with an internal combustion engine, an electric motor connected to an output shaft of the engine through a hydraulic clutch and an automatic transmission connected to an output shaft of the motor to be inputted with an output torque outputted from at least one of the engine and the motor to transmit the output torque to driven wheels of the vehicle, comprising

• initial control conducting means for conducting an initial control to supply priming hydraulic pressure to the clutch to take up dead stroke and to start the engine, when an instruction to switch to vehicle driving powered by the engine is made in a course of vehicle driving powered by the motor;
• engine speed determining means for determining a speed of the engine;
• increase control conducting means for conducting an increase control to increase the output torque of the motor and to increase supply of hydraulic pressure to the clutch in synchronized with the detected engine speed, when the engine is started;
• and
• synchronous control conducting means for conducting a synchronous control to reduce the output torque of the engine for a predetermined period of time such that the engine speed is synchronized with the motor speed when the detected engine speed reaches a predetermined engine speed.

A method of controlling a hybrid vehicle equipped with an internal combustion engine, an electric motor connected to an output shaft of the engine through a hydraulic clutch and an automatic transmission connected to an output shaft of the motor to be inputted with an output torque outputted from at least one of the engine and the motor to transmit the output torque to driven wheels of the vehicle, comprising the steps of:

• (a) conducting an initial control to supply priming hydraulic pressure to the clutch to take up dead stroke and to start the engine, when an instruction to switch to vehicle driving powered by the engine is made in a course of vehicle driving powered by the motor;
• (b) determining a speed difference between speeds of the motor and the engine;
• (c) conducting an increase control to increase the output torque of the motor and to increase supply of hydraulic pressure to the clutch based on the determined speed difference, when the engine is started;
• and
• (d) conducting a synchronous control to reduce the output torque of the engine for a predetermined period of time such that the engine speed is synchronized with the motor speed when the speed difference becomes less than a predetermined threshold value.

A method of controlling a hybrid vehicle equipped with an internal combustion engine, an electric motor connected to an output shaft of the engine through a hydraulic clutch and an automatic transmission connected to an output shaft of the motor to be inputted with an output torque outputted from at least one of the engine and the motor to transmit the output torque to driven wheels of the vehicle, comprising the steps of

• (a) conducting an initial control to supply priming hydraulic pressure to the clutch to take up dead stroke and to start the engine, when an instruction to switch to vehicle driving powered by the engine is made in a course of vehicle driving powered by the motor;
• (b) determining a speed of the engine;
• (c) conducting an increase control to increase the output torque of the motor and to increase supply of hydraulic pressure to the clutch in synchronized with the detected engine speed, when the engine is started;
• and
• (d) conducting a synchronous control to reduce the output torque of the engine for a predetermined period of time such that the engine speed is synchronized with the motor speed when the detected engine speed reaches a predetermined engine speed.