A method is disclosed for monitoring the functions of a friction clutch which is arranged in a vehicle between a drive motor and a compressor of a compressed air supply system and which can be disengaged and engaged pneumatically. In a delivery mode of the compressor, at least one operating parameter is detected by sensor and evaluated in an electronic control unit. When a slipping condition of the friction clutch is identified, a value for a cut-off pressure of the compressor stored in the electronic control unit is reduced. When a slipping condition has been identified, the delivery mode of the compressor is ended by disengagement of the friction clutch, and a warning signal and/or warning information is outputted.

A method for automatically warming up a clutch actuator for a clutch of a transmission in a vehicle, wherein the clutch actuator is operable by use of pressurized fluid and configured to actuate the clutch from an engaged to a disengaged state, and/or vice versa, the method including: identifying if a temperature is below a predetermined temperature value and if the clutch actuator is leaking, and if it is identified that the temperature is below the predetermined temperature value and that the clutch actuator is leaking; then repeatedly pressurizing the clutch actuator by use of the pressurized fluid until a state is reached indicative of the clutch actuator being functional, or until a maximum run out state is reached indicative of a faulty clutch actuator.

This clutch control apparatus includes: a clutch device that connects and disconnects a power transmission between an engine and a drive wheel; a clutch actuator that drives the clutch device and changes a clutch capacity; a driven mechanism that is arranged between the clutch actuator and the clutch device, is operated by a drive of the clutch actuator, and operates the clutch device; a control part that calculates a control target value of the clutch capacity; and a temperature sensor that measures a temperature of the driven mechanism, wherein the control part corrects the control target value based on the temperature measured by the temperature sensor.

Methods and systems are provided for wet clutch pressure control to reduce drag and degradation of rotary seals in a transmission. In one example, a method may include determining an upper threshold pressure based on a rotational speed of a shaft of the transmission, determining a lower threshold pressure based on the rotational speed of the shaft, and adjusting a pressure of hydraulic fluid applied to the clutch to be between the upper threshold pressure and the lower threshold pressure. In this way, the pressure of the hydraulic fluid applied to the clutch may be maintained at a level that allows full torque transfer by the wet clutch while reducing drag on the rotary seals.

A vehicle includes a first axle, a second axle, a driveshaft, a first clutch, a second clutch, a third clutch, and a controller. The second axle has first and second half shafts. The second axle has first and second wheels. The driveshaft is disposed between the first and second axles and is coupled to the second axle. The first clutch is configured to selectively couple the driveshaft to the first axle. The second clutch is configured to selectively couple the first wheel to the first half shaft. The third clutch is configured to selectively couple the second wheel to the second half shaft. The controller is programmed to repeatedly connect the first axle to the second axle via the driveshaft by alternating between (i) closing the second clutch and then the first clutch and (ii) closing the third clutch and then the first clutch.

Method for determining a kisspoint of a clutch. A method is provided of determining a kisspoint of a clutch in a driveline of a vehicle comprising a. increasing a target clutch pressure of a clutch piston up to a first predetermined test target pressure, b. increasing the target clutch pressure up to an upper target pressure and subsequently keeping the target clutch pressure stable for a predetermined time interval, c. monitoring a parameter indicative for the filling of the clutch piston, e.g. the rotational speed of a pump, during the predetermined time interval, d. repeating steps a., b., and c. for at least one further predetermined test target pressure, and e. determining the kisspoint based on the monitored parameter indicative for the filling of the clutch piston.

A method for operating an electrohydraulic transmission clutch of a motor vehicle, wherein, for a clutch operation, a hydraulic pressure is set by way of a regulating device of a controller as a function of a clutch signal, and, through the pressure, a disengagement element of the transmission clutch is moved through a soft region into a rigid region via a rigid point, or vice versa. The soft region is to be compensated for. Further, as a function of the clutch signal, the regulating device generates a preliminary target value signal for the pressure and a time derivative of the preliminary target value signal is generated as a movement signal, and a pilot control generates a pilot control signal as a function of the movement signal, and the preliminary target value signal and the pilot control signal are combined to give a final actuating value signal for the pressure.

A friction engagement element control system is provided, which includes a friction engagement element including friction plates, which are an input-side friction plate and an output-side friction plate, and an actuation system configured to engage the input-side friction plate with the output-side friction plate with a pushing force, the friction plates having a characteristic in which a friction coefficient thereof decreases as a rotational difference between the friction plates increases. The device includes a controller configured to control the pushing force so that the negative slope characteristic becomes a positive slope characteristic in which a frictional force of the friction engagement element decreases as the rotational difference decreases, when engaging the friction engagement element.

A method is disclosed for monitoring the functions of a friction clutch which is arranged in a vehicle between a drive motor and a compressor of a compressed air supply system and which can be disengaged and engaged pneumatically. In a delivery mode of the compressor, at least one operating parameter is detected by sensor and evaluated in an electronic control unit. When a slipping condition of the friction clutch is identified, a value for a cut-off pressure of the compressor stored in the electronic control unit is reduced. When a slipping condition has been identified, the delivery mode of the compressor is ended by disengagement of the friction clutch, and a warning signal and/or warning information is outputted.

Methods and systems are provided for controlling and diagnosing one or more clutches in a transmission. In one example, a method for operation of a vehicle system is provided that includes at a diagnostic controller or processing unit independent from a driveline controller or processing unit, respectively, determining an engagement state of a clutch in a transmission of the vehicle system, wherein the engagement state is selected from a group of three or more clutch engagement states. The method further includes identifying an unauthorized clutch state based on the engagement state of the clutch and a speed of the vehicle and responsive to the identification of the unauthorized clutch state, operating the vehicle system in a fault state.