Method and system for learning and controlling torque transmission kiss point of engine clutch for hybrid electric vehicle

A method of learning a torque transmission kiss point of an engine clutch of a hybrid electric vehicle, in which a point at which the engine clutch of the hybrid electric vehicle driven by output of an engine and a motor, which are engaged and disengaged through the engine clutch, starts to transmit torque is learned and controlled, the method comprising:

• monitoring, by a control unit, power transference of a transmission between the engine and the motor;
• once power transference of the transmission transmitting the output of the engine and the motor is interrupted, learning, by the control unit, a torque transmission kiss point of the engine clutch;
• controlling torque of the motor to be zero and controlling a speed of the engine to reach a target idle speed after beginning to learn the torque transmission kiss point;
• in response to the speed of the engine reaching the target idle speed, measuring a speed of the motor rotated due to a viscosity of the engine clutch and storing the measured speed within the control unit;
• detecting a change of the speed of the motor while increasing hydraulic pressure applied to the engine clutch at a set ratio;
• setting hydraulic pressure when the change of the speed of the motor is greater by a predetermined value or more than the speed of the motor by the viscosity as new torque transmission kiss point hydraulic pressure;
• and
• applying the torque transmission kiss point of the engine clutch to a solenoid valve,
• wherein the transmission is an automatic transmission, and
• when the transmission is in park or neutral, the control unit determines that power transference from the transmission has been interrupted.

A system for learning a torque transmission kiss point of an engine clutch of a hybrid electric vehicle, the system comprising:

• an engine clutch positioned between an engine and a motor of the hybrid electric vehicle to engage and disengage the engine and the motor with a transmission, wherein the transmission is configured to shift power applied to wheels according to an operation of a shift stage lever and provide power accordingly;
• an integrated starter and generator (ISG) configured to start up the engine or generate power;
• and
• a control unit configured to learn the torque transmission kiss point of the engine clutch by controlling driving of the engine, the motor, the transmission, the ISG, and the engine clutch in an appropriate condition and monitoring states of the engine, the motor, the transmission, the ISG, and the engine clutch,
• wherein the control unit executes program instructions via a processor that perform a method of learning a torque transmission kiss point of an engine clutch of a hybrid electric vehicle, the method comprising:
• determining whether power transference of a transmission transmitting the output of the engine and the motor has been interrupted;
• determining whether the engine is on only when the power transference of the transmission has been interrupted;
• controlling the motor so that a speed of the motor is maintained at a set speed different from a revolution speed of the engine only when the power transference of the transmission is determined to have been interrupted and the engine is on;
• detecting a state change of the motor while increasing hydraulic pressure applied to the engine clutch at a set ratio;
• calculating a torque transmission kiss point of the engine clutch based on the state change of the motor;
• and
• applying the torque transmission kiss point of the engine clutch to a solenoid valve,
• wherein the transmission is an automatic transmission, and
• when the transmission is in park or neutral, the control unit determines that power transference from the transmission has been interrupted.

A non-transitory computer readable medium containing program instructions executed by a processor within a control unit, the computer readable medium comprising:

• program instructions that determine whether power transference to a transmission transmitting an output from an engine and a motor has been interrupted;
• program instructions that determine whether the engine is on only when the power transference of the transmission has been interrupted;
• program instructions that control the motor so that a speed of the motor is maintained at a set speed different from a speed of revolutions of the engine only when the power transference of the transmission is interrupted and the engine is driven;
• program instructions that detect a state change of the motor while increasing hydraulic pressure applied to an engine clutch at a set ratio;
• program instructions that calculate a torque transmission kiss point of the engine clutch based on the state change of the motor;
• and
• program instructions that apply the torque transmission kiss point of the engine clutch to a solenoid valve,
• wherein the transmission is an automatic transmission, and
• when the transmission is in park or neutral, the control unit determines that power transference from the transmission has been interrupted.