A method and device for controlling an engine clutch of a hybrid vehicle are provided. The method includes setting a target speed of an engine to change a driving mode of the hybrid vehicle from an EV mode to an HEV mode and operating a HSG to adjust an engine speed to reach the target speed. An engine clutch that connects the engine with a driving motor or disconnects the engine from the driving motor is engaged to start when the speed of the engine is maintained at the target speed. A kiss point generated when the engine clutch is in a slip state is detected to learn the kiss point of the engine clutch and an output of the engine is increased based on a driver required torque when the speed of the engine and a speed of the driving motor are synchronized after the kiss point is learned.

A continuously variable transmission, a control system, and a method are provided. The control system and method are configured to learn a desired running pressure to be applied to a clutch that is lower than a pulley clamping pressure and higher than a pressure at which the clutch would slip (a clutch critical pressure), so that the clutch can act as a fuse to avoid pulley slip. A plurality of clutch slip tests are performed, each of which include decreasing pressure supplied to the clutch until a clutch slip occurs. Clutch slip data points are collected at the point of slip and used to determine a gain and an offset, where the gain is a clutch pressure versus clutch torque capacity gain, and the offset is a clutch pressure offset, which is used to determine the clutch critical pressure.

A method for learning an engine clutch kiss point of a hybrid vehicle includes: controlling, by a controller, an engine clutch which connects an engine with a motor or disconnects the engine from the motor so that the engine clutch is engaged after the controller checks stop of the engine and of the motor and stabilization operation for a hydraulic pressure line of the engine clutch is performed; controlling the motor to have a certain speed after the stabilization operation; controlling the engine clutch to be engaged after speed of the motor is stabilized; determining whether torque variation of the motor when the engine clutch is engaged is equal to or greater than a threshold value; and determining a hydraulic pressure at which the torque variation is the threshold value as the kiss point of the engine clutch.

A method for learning an engine clutch kiss point of a hybrid vehicle includes: controlling, by a controller, an engine clutch which connects an engine with a motor or disconnects the engine from the motor so that the engine clutch is engaged after the controller checks stop of the engine and of the motor and stabilization operation for a hydraulic pressure line of the engine clutch is performed; controlling the motor to have a certain speed after the stabilization operation; controlling the engine clutch to be engaged after speed of the motor is stabilized; determining whether torque variation of the motor when the engine clutch is engaged is equal to or greater than a threshold value; and determining a hydraulic pressure at which the torque variation is the threshold value as the kiss point of the engine clutch.

A method for learning a touch point of an engine clutch of a hybrid electric vehicle including a motor connected to a transmission and an engine selectively connected to the motor through the engine clutch includes determining whether a learning condition of the touch point of the engine clutch is satisfied, releasing a transmission clutch and controlling a motor speed when the learning condition is satisfied, increasing a coupling pressure of the engine clutch when a change amount of the motor speed is less than a first predetermined value, comparing a change amount of a motor torque according to the increased coupling pressure of the engine clutch with a second predetermined value, and learning the touch point of the engine clutch when the change amount of the motor torque is greater than or equal to the second predetermined value.

The invention relates to a method for determining an engagement point of a hybrid clutch in a hybrid vehicle; which hybrid clutch is actuated by a hydrostatic clutch actuator and disconnects or connects an internal combustion engine and an electric traction drive; the engagement point is determined by slowly actuating the clutch starting from a position in which the hybrid clutch is in the non-actuated state, and monitoring a moment of the electric traction drive when a defined increase in the momentum is detected. In a method in which engagement point adaptation is optimized, a current engagement point (tp) is adapted during operation of the hybrid vehicle using a start-up routine, by which a first engagement point is determined when the hybrid vehicle is started; the hybrid clutch is moved close to a previously determined engagement point, and starting from said last determined engagement point, the hybrid clutch is displaced further until the defined increase in the moment is detected.

Methods are provided for checking the actuating accuracy of a clutch arranged in a force flow between a fixable shaft and an electric machine of an electric or hybrid motor vehicle when at a standstill. One method includes: fixing the shaft, setting a defined setpoint torque on the clutch to be checked, continuously ramping up the electric machine up until the first slipping of the clutch, comparing the achieved torque of the electric machine with the setpoint torque preset on the clutch. Another method includes: fixing the shaft, ramping up the electric machine to a defined rotational speed, setting a defined setpoint torque on the clutch to be checked, comparing the torque of the electric machine needed to maintain a constant rotational speed with the setpoint torque set on the clutch.

Methods and systems for operating a clutch of an axle are provided. In one example, the clutch may be characterized in static or dynamic conditions. The clutch characterization may be a basis for subsequently operating the clutch during gearbox shifting. In particular, an amount of torque that is transferred via the clutch may be controlled or adjusted according to the clutch characterization.