A four-wheel drive vehicle comprises: a dog clutch; an electronically controlled coupling; and a control device switching a drive state to the four-wheel drive state when the control device determines that a running road surface is a low friction road and switching the drive state to the two-wheel drive state when the control device determines that the running road surface is a high friction road. In the case of switching the drive state from the four-wheel drive state to the two-wheel drive state, the control device temporarily releases the electronically controlled coupling to redetermine whether the running road surface is the low friction road or the high friction road before releasing the dog clutch and prohibits switching from the four-wheel drive state to the two-wheel drive state when it is redetermined that the running road surface is the low friction road.

Methods and systems are provided for operating a vehicle that includes a torque vectoring electric machine. In one example, torque output of a torque vectoring electric machine is adjusted to reduce driveline torque disturbances when the torque vectoring electric machine is activated. The torque output is adjusted in response to a speed difference between a wheel speed and a speed of the torque vectoring electric machine.

Methods and systems are provided for operating a vehicle that includes a torque vectoring electric machine. In one example, torque output of a torque vectoring electric machine is adjusted to reduce driveline torque disturbances when the torque vectoring electric machine is activated. The torque output is adjusted in response to a speed difference between a wheel speed and a speed of the torque vectoring electric machine.

A drive force control system for a vehicle configured to allow a driver to find out a steering angle at which a wheel grips a road surface. In the vehicle, a torque distribution ratio to a pair of wheels turned by a steering wheel and another pair of wheels is changeable. A controller restricts a control to change the torque distribution ratio in the event of a slip of the pair of wheels, if a steering angle of the pair of wheels is changed to allow the pair of wheels to grip a road surface.

Methods and systems for a locking mechanism in an inter-axle differential are provided. A vehicle system, in one example, includes an electric motor coupled to a clutch assembly in a locking mechanism of an inter-axle differential coupled to a first axle and a second axle, the clutch assembly is configured to selectively disengage the locking mechanism, and in the disengaged configuration the locking mechanism permits speed differentiation between the first and second axles. The system further includes an electric motor brake coupled to the electric motor and configured to selectively apply a brake torque to the electric motor and the electric motor is configured to actuate the clutch assembly.

Methods and systems for a locking mechanism in an inter-axle differential are provided. A vehicle system, in one example, includes an electric motor coupled to a clutch assembly in a locking mechanism of an inter-axle differential coupled to a first axle and a second axle, the clutch assembly is configured to selectively disengage the locking mechanism, and in the disengaged configuration the locking mechanism permits speed differentiation between the first and second axles. The system further includes an electric motor brake coupled to the electric motor and configured to selectively apply a brake torque to the electric motor and the electric motor is configured to actuate the clutch assembly.

A drive force transmission apparatus is mountable on a four-wheel drive vehicle switchable between a four-wheel drive mode that transmits a drive force of an engine to front wheels and rear wheels, and a two-wheel drive mode that transmits the drive force to only the front wheels. The drive force transmission apparatus allows adjustment of the drive force to the rear wheels, and includes a multi-plate clutch, a piston for axially pressing the multi-plate clutch, an actuator for axially moving the piston, and a control unit for controlling the actuator. Upon satisfaction of a predetermined condition that indicates a high probability of the vehicle needing to be switched from the two-wheel drive mode to the four-wheel drive mode, the control unit causes the actuator to displace the piston by a predetermined amount with respect to an initial position of the piston toward the multi-plate clutch.

A disconnect including: an input hub; an output race including a radially inner surface with ramps; wedge plate segments radially disposed between the input hub and the output race, each segment including a ramp in contact with an outer race ramp; an actuator cage; and an actuator plate. For a connect mode, the input hub, the wedge segments, and the output race transmit torque from an electric motor of an electrically-powered vehicle to a wheel of the vehicle. In a disconnect mode, relative rotation between the input hub and the output race is enabled. To transition from the connect mode to the disconnect mode: the actuator plate is displaced by an actuator; the actuator plate axially displaces the actuator cage; and the actuator cage circumferentially displaces the wedge plate segments to decrease or break frictional contact between the wedge plate segments and the input hub.

A disconnect including: an input hub; an output race including a radially inner surface with ramps; wedge plate segments radially disposed between the input hub and the output race, each segment including a ramp in contact with an outer race ramp; an actuator cage; and an actuator plate. For a connect mode, the input hub, the wedge segments, and the output race transmit torque from an electric motor of an electrically-powered vehicle to a wheel of the vehicle. In a disconnect mode, relative rotation between the input hub and the output race is enabled. To transition from the connect mode to the disconnect mode: the actuator plate is displaced by an actuator; the actuator plate axially displaces the actuator cage; and the actuator cage circumferentially displaces the wedge plate segments to decrease or break frictional contact between the wedge plate segments and the input hub.

A vehicle driveline system for a vehicle is provided. The system comprises a differential having a differential housing connectable to an engine via a pinion, and two output shafts being connectable with respective wheel axles, and an electrical motor being selectively connected to the differential housing. The differential housing extends into a hollow shaft having a radial protrusion provided with engagement means, such as splines, for connecting with a shifting sleeve, wherein said shifting sleeve is configured to be actuated for connecting the electrical motor to said differential housing.