A wet multi-plate clutch includes: a piston movable between a transmission position where the piston pushes a clutch plate group including a plurality of inside clutch plates supported on an inside cylinder and a plurality of outside clutch plates supported on an outside cylinder, in an axial direction to cause friction between the inside and outside clutch plates, and a disconnection position where the piston is spaced apart from the clutch plate group; and a movable wall configured to move integrally with the piston. The disconnection position includes a first disconnection position and a second disconnection position where the distance between the clutch plate group and the piston is longer than at the first disconnection position. When the piston is positioned at the first disconnection position, a first through hole provided in the inside cylinder and a second through hole provided in the movable wall overlap in the radial direction.

A driving-force transmitting apparatus 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.

A hydraulic system including a hydraulically actuated clutch, a hydraulically actuated shifting piston, and a pressure source for actuating the clutch as well as the shifting piston. The movement of the shifting piston also controls a valve function which serves to open a connection from the pressure source to the clutch only when the shifting piston has reached one of its end positions.

A method of controlling an all-wheel-drive system connect event including providing a power transmission apparatus having a clutch, a propeller shaft, and a rear drive unit with a clutch pack assembly. The rear drive unit clutch pack is actuated by creating a model of the propeller shaft rotational speed, adapting the model parameters to compensate for temperature and vehicle wheel speed, storing the model, adapting the model utilizing information collected during a previous all-wheel-drive system connect event, and developing a set point for the clutch driving element utilizing the model and a multi-loop control architecture. The power transmission apparatus clutch is then engaged.

A mechanical front wheel drive roller wedging control system includes a 4WD switch in a vehicle operator station, a roller cage drag mechanism electrically activated by the 4WD switch and providing a drag on a roller cage if the 4WD switch is in an on position, and a throttle pedal switch actuated by the throttle pedal and that deactivates the roller cage drag mechanism when the throttle pedal is released. In an alternative embodiment, a controller may deactivate the roller cage drag mechanism when a throttle position sensor or engine speed sensor is below a minimum value.

A method for operating a drivetrain for a motor vehicle, said method includes: reducing a transmission torque transmitted between a primary drive axle operatively connected with a secondary drive axle of the motor vehicle via a clutch configured to allow adjustment of the transmission torque when determining at the secondary drive axle a wheel slip which exceeds a defined slip threshold value.

A power transfer assembly for a motor vehicle includes a clutch protection system to prevent damage to an actively-controlled multi-plate mode clutch of the power transfer assembly. The clutch protection system includes a transfer case control module (TCCM) and an engine control module (ECM) configured to regulate the distribution of torque applied from an engine to front and rear output shafts of the power transfer assembly. The TCCM is in operable communication with the engine control module ECM, wherein TCCM is configured to detect slip in the actively-controlled multi-plate friction clutch and to communicate with the ECM to selectively reduce the output torque of the engine in response to detected slip.

To provide a device to facilitate protection of a clutch while minimizing degradation of the torque transmission performance. A hydraulic clutch for drive power distribution is provided between a drive power source and auxiliary driving wheels, and a commanded torque is determined depending on the travel situation. The hydraulic pressure corresponding to the commanded torque is supplied to the hydraulic clutch. The surface temperature of the clutch is estimated (detected). The device generates a limiting value to limit the commanded torque when the difference in rotation between input and output shafts of the clutch is not less than a predetermined threshold and the commanded torque is not less than a predetermined value and performs control so as to increase the limiting value with an increase in the surface temperature of the clutch.

Accurate control is to be performed while taking an advantage of the hydraulic pressure sealing-type control. A control device of a vehicle includes a hydraulic chamber (15) into which a hydraulic pressure operating a power transmission element (10) is introduced, a first pressure regulating mechanism (35, 37) and a second pressure regulating mechanism (43) that switch hydraulic pressure in the hydraulic chamber (15), and a control device (50). The control device (50) can switch a first state in which the pressure regulating mechanism (35, 37) is in a pressure rising state and the second pressure regulating mechanism (43) is in a holding state so as to increase pressure of the hydraulic chamber, and a second state in which the second pressure regulating mechanism (43) is in a non-holding state so as to decompress the hydraulic chamber.

An AWD-vehicle control device includes a transfer clutch that adjusts a driving force, a detector that detects a steering angle of a steering wheel, a detector that detects an accelerator pedal opening, a detector that detects a vehicle speed, a detector that detects an engine revolution speed, a detector that detects a turbine revolution speed of a torque converter, and a transfer clutch controller that adjusts hydraulic pressure supplied to the transfer clutch and controls a coupling force of the transfer clutch. If a predetermined period has passed from the accelerator pedal opening becoming less than a predetermined opening, the vehicle speed is within a predetermined range, a deviation between the engine and turbine revolution speeds is less than a predetermined speed, and the steering angle is equal to a first predetermined angle or greater, the transfer clutch controller controls the hydraulic pressure to reduce the coupling force.