A method of setting a clutch control reference value may make it possible to more accurately learn the VKP of a hydraulic multi-plate clutch controlled by a solenoid valve, improving the accuracy of clutch control, and furthermore, to improve the quality of shifting a vehicle by the precise control of a transmission provided with such a clutch.

A method of setting a clutch control reference value may make it possible to more accurately learn the VKP of a hydraulic multi-plate clutch controlled by a solenoid valve, improving the accuracy of clutch control, and furthermore, to improve the quality of shifting a vehicle by the precise control of a transmission provided with such a clutch.

Systems and methods for operating a vehicle that includes an engine and an electric machine are described. In one example, an actual total number of transmission gear downshifts are counted to determine whether or not a transmission clutch characterization is immature. The transmission clutch characterization may be adjusted if it is determined to be immature.

A method for determining reference values of a sensor is provided. The reference values correspond to a disengaged operating condition or to an engaged operating condition of a form-locking shift element (A, F). With the aid of the sensor, at least one operating parameter of the shift element (A, F) determinable during a disengagement and during an engagement of the shift element (A, F). A torque, an actuation force of the shift element (A, F), and a differential speed between shift-element halves of the shift element (A, F) are varied during the determination of the reference values of the sensor in such that the form-locking shift element (A, F) is transferred into the disengaged operating condition or into the engaged operating condition.

A control method of a clutch for a vehicle may include determining whether or not learning of clutch characteristics is possible; learning the clutch characteristics when the learning of the clutch characteristics is possible; determining a clutch torque for controlling the clutch in consideration of a change amount in the clutch torque before and after the learning and controlling the clutch by the determined clutch torque; and determining whether or not it is difficult to continue to learn the clutch characteristics.

A method of detecting a ball loss condition in a ball and ramp assembly. The method includes providing a drive unit having one or more clutch pack assemblies, one or more motors with a motor output shaft and one or more ball and ramp assemblies. One or more actuation profiles are ran by the motors and an amount of motor current used and a position of the output shaft of the motor is measured during the running of actuation profiles. One or more motor current vs. motor output shaft position plots are generated having one or more characteristic curves based on the amount of current measured and the position of the output shaft measured. The amount of motor current is compared to the motor current of characteristic curve at a given output shaft position and based on that comparison a ball loss condition is identified.

This clutch control device is provided with: a supply valve and a supply valve control unit, which control the supply of an operating fluid to a pressure chamber; a first discharge valve and a first discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber; and a second discharge valve and a second discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber. When it is determined that the engagement and disengagement switching of a clutch device 2, which is necessitated by the discharge of the operating fluid in the pressure chamber, is required, the first discharge valve is controlled to be opened and then the second discharge valve is controlled to be opened.

Systems and methods for operating a vehicle that includes an engine and an electric machine are described. In one example, an actual total number of transmission gear downshifts are counted to determine whether or not a transmission clutch characterization is immature. The transmission clutch characterization may be adjusted if it is determined to be immature.

A method for controlling an engine clutch includes steps of controlling the hydraulic pressure transmitted from a master cylinder, driven by a motor, to a concentric slave cylinder using a controller outputting a motor control command for controlling an engine clutch so as to switch the engine clutch to a target state, driving the engine clutch using the concentric slave cylinder, after the step of controlling hydraulic pressure, detecting a position of a piston of the master cylinder using a first travel sensor and detecting a position of a piston of the concentric slave cylinder using a second travel sensor, and performing compensation control with respect to the motor based on the positions of the pistons detected by the first travel sensor and the second travel sensor using the controller so that the engine clutch is switched to the target state.

A vehicle includes an engine, a transmission, and a controller. The transmission has clutches, a circuit configured to transport fluid to the clutches, a pump configured to circulate the fluid through the circuit, and an accumulator disposed along the circuit. The controller is programmed to, responsive to an engine start and a fluid temperature being less than a temperature threshold, discharge the accumulator to prime the pump.