Actual pressure of a hydraulic clutch of a motor vehicle can be regulated by: a) providing a value for a desired pressure to be present in a clutch cylinder; b) filling the clutch cylinder with hydraulic fluid to achieve the desired pressure; c) wherein, if the desired pressure lies between 0 and 7 bar, the actual pressure in the clutch cylinder is adjusted by regulating a rotational speed of the pump of the electric motor, and if the desired pressure is greater than 7 bar, the actual pressure in the clutch cylinder is adjusted by regulating a motor current of the electric motor; d) regulating the actual pressure until the desired pressure is achieved.

A system is configured to control a clutch that connects a first rotating body and a second rotating body. The system includes a biasing portion, an actuator, an energization device, and a control unit. The biasing portion permanently biases the clutch in a connecting direction. The actuator drives the clutch in a disconnecting direction. The energization device energizes the actuator. The control unit controls the energization device. The energization device outputs a first current value to the actuator when a connection of the clutch is detected even if a condition for permitting a disconnection is satisfied. The energization device outputs a second current value lower than the first current value when the condition for permitting the disconnection is satisfied and a disconnection of the clutch is detected.

A control apparatus controls a driving force transmission device including: an electric motor; a pressing mechanism to convert the rotational force of the motor into an axial pressing force; friction clutches including friction members configured to come into frictional engagement with each other by the pressing force provided by the pressing mechanism. The driving force transmission device is configured to transmit a driving force between a pair of rotary members by the friction clutches. The apparatus includes: a target current calculating circuit to calculate a target current to be supplied to the motor, and a correction circuit to correct a voltage to be applied to the motor so as to reduce a difference between the target current and an actual current supplied to the motor. The correction circuit increases or reduces, in accordance with the actual current, the amount of correction of the voltage to be applied to the motor.

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.

A vehicle drive device includes: an electric motor; a multi-plate clutch including a plurality of clutch plates; a pressing mechanism configured to press the multi-plate clutch; an output rotary member to which a drive force of the electric motor is transferred through the multi-plate clutch; and a control device configured to control the electric motor and the pressing mechanism. The control device is configured to control the pressing mechanism using information on the result of test operation performed while the vehicle is stationary.

An electromechanical vehicle brake has an electric motor and an actuation piston, which acts on a braking assembly, as well as a ball screw drive. The ball screw drive comprises a spindle rotatable by the electric motor and a ball screw nut displaceable on the spindle. The ball screw nut is received in the actuation piston and cooperates with a stop on an inner axial end of the actuation piston to displace the actuation piston in an actuation direction. A spring element is arranged in the actuation piston between the stop and the ball screw nut. A travel sensor measures a linear displacement of the actuation piston. With the aid of the signal of the travel sensor, which indicates a displacement position of the actuation piston, a braking force currently applied by the actuation piston to the braking assembly is determined under consideration of the characteristic curve of the spring element.

A driving force transmission device includes an input rotation member, an output rotation member, a multiple-disc clutch, a pressing mechanism, and a control device including a current supply circuit. The control device is configured to compute a torque command value, to compute a current command value, to correct the current command value, and to control the current supply circuit such that an electric current depending on the current command value is supplied to the pressing mechanism. The control device is configure to correct the current command value by a correction amount in a constant-torque state after the torque command value changes, the constant-torque state being a state where a change rate of the torque command value is in a predetermined range, the correction amount depending on a duration of the constant-torque state.

A method of setting a clutch control reference value includes monitoring the pressure of a clutch while a controller applies test current having a predetermined amplitude and frequency to a solenoid valve in the manner of gradually reducing the magnitude of the test current from a predetermined entry value, applying, when the amplitude of the pressure of the clutch starts to change, predetermined checking current, the checking current vertically oscillating based on the magnitude of current when the amplitude of the pressure of the clutch starts to change as a central value, and determining a volumetric kiss point (VKP) by comparing the amplitude of the pressure of the clutch according to application of the checking current with a predetermined reference range.

Methods and systems are provided for a differential disconnect assembly of a vehicle, the differential disconnect assembly including a dog clutch used to engage and disengage a gear of a differential of the vehicle from a transmission of the vehicle. In one example, a method for operating a dog clutch comprises de-energizing a solenoid coupled to the dog clutch to initiate dog clutch disengagement; and during disengagement of the dog clutch when a return spring coupled to a first toothed interface of the dog clutch applies a first force on the first toothed interface in a first direction away from a second toothed interface, transiently re-energizing the solenoid that applies a second force to the first toothed interface in a second direction which is opposite the first direction.

A method for determining a kiss point is disclosed. A drive unit having one or more motors with a motor output shaft is provided. One or more actuation profiles are ran and an amount of motor current and motor shaft position data is measured. The data measured is filtered and one or more motor current vs. motor shaft position plots having one or more curves with a high force and high current region are generated. A derivative is calculated over the curves and a slope of the high force and high current region is determined. A relative slope threshold is determined by multiplying the slopes by a predetermined percentage. One or more lines having a slope substantially equal to the relative slope threshold are plotted. The kiss point is determined based on the position of the motor shaft where the derivative of the curves equals the slope of the lines plotted.