A control device is to be applied to a four-wheel drive vehicle including a first coupling device interposed between a rear-wheel final gear device and a rear left wheel axle and a second coupling device interposed between the rear-wheel final gear device and a rear right wheel axle. The control device includes a controller changes a coupling torque of the first coupling device and a coupling torque of the second coupling device independently of each other. The controller estimates, when the vehicle is accelerating, a vehicle body speed of the vehicle under a state in which the coupling torque of any one of the first coupling device and the second coupling device is set to a value larger than zero and the coupling torque of another one thereof is set to zero. Thereby, the control device can accurately estimate the vehicle body speed when the vehicle is traveling while accelerating.

One vehicle wheel is disconnected from a differential while the vehicle is in a front wheel drive mode. A controller checks for a malfunction of the differential while the vehicle is in the front wheel drive mode and in response to a request to enter an all wheel drive mode. If speeds of the other vehicle wheel and the differential input indicate that the malfunction is present, the all wheel drive mode is disabled and the driver is informed. If fluid temperature indicates a risk of the malfunction, all wheel drive mode is temporarily disabled and the driver is informed. If the temperature condition continues to be present for a predetermined duration, the all wheel drive mode is disabled.

A four-wheel-drive vehicle includes: a pump that is actuated by an electric motor; a friction clutch that has a plurality of clutch plates that are pressed by a piston that is movable by working oil discharged from the pump; a control device that controls the electric motor; front wheels, to which a drive force of an engine is always transferred; and rear wheels, to which the drive force of the engine is transferred in accordance with the fastening force of the friction clutch. When it is determined that the vehicle is in a high fastening force-requiring state in which it is necessary for the friction clutch to transfer a large drive force temporarily, the control device causes the electric motor to output torque that is larger than torque that the electric motor can continuously output.

A differential device includes: a differential case on which a meshed portion is formed; a tubular slide member that has a meshing portion; a differential gear mechanism disposed inside the slide member; a pinion gear shaft that supports pinion gears of the differential gear mechanism; and an actuator that moves the slide member in the axial direction. The slide member has a cylindrical portion, on one side of which in the axial direction the meshing portion is formed, and a long hole that extends in the axial direction of the cylindrical portion and that opens toward the other side in the axial direction, which is the opposite side from the meshing portion. The pinion gear shaft is fitted with the long hole, and supported by the slide member. A reinforcing ring that suppresses deformation of the slide member is attached to an end portion of the cylindrical portion in which the long hole opens.

A clutch apparatus includes a clutch hub, a clutch drum, a multi-plate clutch having inner clutch plates and outer clutch plates, a piston for pressing the multi-plate clutch, an electric motor, a moving mechanism for moving the piston in an axial direction in accordance with the amount of rotation of the electric motor, and a control unit for controlling the electric motor. When increasing a rotational force that is transmitted between the clutch hub and the clutch drum by increasing electric current that is supplied to the electric motor, the control unit moves the piston in the axial direction by temporarily supplying the electric motor with the electric current having a first current value that is greater than a second current value corresponding to a target rotational force that needs to be transmitted between the clutch hub and the clutch drum.

A system and method for electronically controlling a limited slip differential is disclosed. The method includes determining, by an electronic controller of a vehicle, a request for a limited-slip-differential coupling torque to be applied. The request is based upon an estimation of the vehicle's mass. The method also includes transmitting the request to an electronic limited slip differential of the vehicle. The electronic limited slip differential is configured to apply the requested limited-slip-differential coupling torque.

Provided is a control device for a hybrid vehicle including a controller that performs a control of the hybrid vehicle including an engine and an electric motor that serve as driving sources, a transmission, and first and second clutches. The first clutch is provided between the engine and the transmission. The second clutch is provided between the transmission and driving wheels. The controller includes first and second control units. The first control unit performs a control, in a motor traveling mode, to bring the first clutch to a disengaged state. The motor traveling mode includes traveling solely with the electric motor being driven. The second control unit performs a control, in the motor traveling mode, to bring the second clutch to a mildly engaged state in which input, from the driving-wheel side, of torque larger than driving torque causes the second clutch to slide.

For the operation of a gearless clutch-controlled differential unit with a first clutch and a second clutch, without abandoning the possibility of assigning different torques to the clutches, it is provided that a control variable originally generated by a control variable unit is supplied to the first clutch unchanged while the control variable is supplied to the second clutch subject to the intermediate connection of an individual control element. The first and second clutches have clutch characteristics that are distinct from one another.

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.

A dog clutch includes: a first rotational member; a second rotational member; a clutch member; an electromagnetic coil; and a position detecting portion. A control method for the dog clutch, includes: supplying an exciting current to the electromagnetic coil when the clutch member is moved from the non-connecting position toward the connecting position; and promptly reducing the exciting current when the position detecting portion detects that the clutch member has moved to the connecting position.