A system and method for determining a remaining useful life of a portion of a wet clutch system is provided. The system comprises a first clutch assembly, a proportional valve, a sensor, and a controller. The proportional valve regulates a pressure applied to the first clutch assembly. The sensor measures a response of the first clutch assembly during one of engaging and disengaging a first portion of the first clutch assembly with a second portion of the first clutch assembly. The controller controls the proportional valve, calculates a mean coefficient of friction of the first clutch assembly based on the sensed response of the first clutch assembly, and determines a remaining useful life of a portion of the wet clutch system based on the mean coefficient of friction of the first clutch assembly.

A method for controlling clutch pressure in an electronically controlled limited slip differential comprises receiving a target clutch pressure command indicative of a desired differential torque transfer setting. Processing the target clutch pressure command comprises estimating one of a motor current or a motor speed, calculating an integrated error of a target motor current or an integrated error of a target motor speed, calculating gains over time based on the estimated motor current or the estimated motor speed and based on the integrated error of the target motor current or the integrated error of the target motor speed, applying the calculated gains thereby forming a closed loop feedback, and calculating an oscillation. The target motor current or the target motor speed is applied to a motor connected to a clutch in the differential according to the calculated oscillation to control the clutch pressure of the differential.

According to one embodiment, a current detection circuit (12) includes: a detection resistor (Rs) provided between a solenoid valve (106) and a solenoid driver (11); an amplification unit (121) configured to amplify a detected voltage of the detection resistor (Rs); an AD converter (122) that is driven by a reference voltage (Vref) generated based on a reference current (Iref) and configured to convert an output voltage from the amplification unit (121) into a digital value and output the digital value as a detected current value (D1); and a correction unit configured to perform a correction on the detected current value (D1). The correction unit includes: a temperature sensor (123); a storage unit (125) configured to store information about temperature characteristics of the detected current value (D1) generated due to temperature characteristics of a reference current in each of two or more different temperature regions; and an operation unit configured to apply, to the detected current value (D1), a first correction coefficient calculated based on a detection result of the temperature sensor (123) and information about temperature characteristics of the detected current value (D1) stored in the storage unit (125).

A dual-clutch transmission includes a hydraulic system for actuating hydraulic cylinders of the clutches and the shifting elements. The hydraulic system has a pressure accumulator providing an accumulated pressure in the hydraulic system, and control valves actuatable by a control unit and respectively arranged in pressure lines routed to the hydraulic cylinders of the clutches to adjust the hydraulic pressure applied to the clutches. Pressure sensors associated with the control unit detect the hydraulic pressure. The control unit activates a pressure reduction mode when detecting a long vehicle downtime, and the accumulated pressure can be reduced in the pressure reduction mode, in which the control unit continuously opens the control valve associated with one clutch. Additionally, the pressure sensor associated with the first clutch together with the control unit is integrated into a control circuit in which the first pressure sensor assumes the detection of the actual accumulated pressure value.

A method for determining a torque acting at a position of a drive train of an agricultural towing vehicle, includes controlling a clutch of the drive train between a closed state and an open state, capturing a drive-side rotational speed at the clutch via a first rotational speed sensor, capturing an output-side rotational speed at the clutch via a second rotational speed sensor, controlling the clutch in the direction of the open state, determining, during controlling the clutch, a difference between the rotational speeds on the drive and output sides, comparing the difference with a predetermined difference limit value, capturing the value of a physical variable that causes the clutch control on the basis of the comparison result, and determining the torque on the basis of the captured value of the physical variable.

A hydraulic system for an automatic gearbox for a motor vehicle, includes a high-pressure circuit which includes a pressure accumulator, at least one clutch and actuators, and a low-pressure circuit for cooling the clutch, the high-pressure circuit and the low-pressure circuit each containing a hydraulic cooling pump and a hydraulic charging pump that can be driven by a shared electric motor; and a controller which, when it is detected that the pressure accumulator needs to be charged, controls the electric motor to run at a charging setpoint speed, and/or, when it is detected that cooling is needed or another need exists, controls the electric motor to run at a cooling setpoint speed or another setpoint speed. When the pressure accumulator does not need to be charged and there is no need for cooling and no other need, the controller reduces the setpoint speed to zero for a specified period. At the end of the period the controller controls the electric motor to run at least at the test speed.

A driving-force transmitting apparatus 1 includes first and second friction clutches, a piston that presses the first and second friction clutches, a hydraulic pump that feeds hydraulic oil to a cylinder chamber in the piston, an electric motor that drives the hydraulic pump, and a control apparatus that controls the electric motor to adjust the discharge pressure of the hydraulic pump. The control apparatus has a feedback control apparatus that controls the electric motor using a correction value based on a deviation between a target value and an actual value of the discharge pressure of the hydraulic pump, a hydraulic-oil temperature estimating apparatus that estimates a temperature of hydraulic oil, and a gain adjusting apparatus that changes a correction amount for feedback control in accordance with the estimated temperature of the hydraulic oil.

The invention relates to a clutch device for a drivetrain of a motor vehicle, including a pressure plate which is preferably displaceable in the axial direction of the clutch device, wherein the pressure plate, in a coupled position of the clutch device, presses a clutch disk against a counterpressure plate that can be connected to a crankshaft of an internal combustion engine, and including an actuating device which has a displaceable actuating piston. The displacement position of the actuating piston defines a position of the pressure plate and the actuating piston can be driven by a drive unit of the actuating device in order to displace the pressure plate between the coupled position and an uncoupled position. The drive unit has at least one pump, and the at least one pump is accommodated in a pump seat housing and the pump seat housing is connected to the counterpressure plate in such a way as to rotate therewith.