A clutch device includes a plurality of clutches; a plurality of cylinder chambers provided to respectively correspond to the clutches; a pump configured to discharge a hydraulic fluid; a plurality of control valves each of which is configured to control the hydraulic fluid supplied from the pump to a corresponding one of the cylinder chambers; and an oil passage that distributes the hydraulic fluid discharged from the pump, to the control valves. The oil passage includes at least one split point at which the hydraulic fluid discharged from the pump splits. At least one check valve is provided between the at least one split point and at least one control valve among the control valves, the at least one check valve being configured to block a flow of the hydraulic fluid in a direction from the at least one control valve toward the at least one split point.

A control device is mountable on a four-wheel drive vehicle including a main drive wheel and an auxiliary drive wheel, and is configured to control a drive force transmission device configured to transmit a drive force to the auxiliary drive wheel. The control device includes a processor and a memory storing a program, when executed by the processor, to cause the control device to change a control characteristic of the drive force transmission device that indicates a relationship between a vehicle state of the four-wheel drive vehicle and a drive force transmitted to the auxiliary drive wheel in response to an input from the input device.

A power transmission device is provided, which includes a main-drive-wheel drive part, and an auxiliary-drive-wheel drive part having a power extraction part which has a transfer gear set comprised of a transfer drive gear connected to the main-drive-wheel drive part and a transfer driven gear meshing with the transfer drive gear and configured to transmit power to the auxiliary drive wheels. In a power transmission path from the main-drive-wheel drive part to the transfer drive gear, an input shaft connected to the main-drive-wheel drive part and a power transmission shaft connected to the transfer drive gear are coupled to each other in a radial direction through a first spline having a first backlash. A first shear damper without backlash and a second shear damper provided with a second spline having a second backlash smaller than the first backlash are provided between the input shaft and the power transmission shaft.

Related are a method and an apparatus for protecting a clutch in a vehicle driving process. The method comprises: acquiring a current oil temperature of a space where the clutch is located and judging whether the current oil temperature is within a set temperature interval or not; in a case where the current oil temperature is within the set temperature interval, detecting whether a current wheel speed difference between front shaft and rear shaft reaches to a set wheel speed difference threshold or not; and in a case where the current wheel speed difference between the front shaft and rear shaft reaches to the set wheel speed difference threshold, triggering a first protective mode that is preset to protect the clutch; and in a case where the current oil temperature is higher than the set temperature interval, triggering a second protective mode that is preset to protect the clutch.

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.

A weight ratio of each driving wheel of the vehicle at the time of automatic driving is calculated, a front and rear distribution ratio of a driving force of the vehicle is calculated from the weight ratio, a rear wheel plan driving force is calculated from the front and rear distribution ratio and an action plan required driving force, and a temperature of a rear wheel motor is estimated. Then, when the estimated attainment temperature of the rear wheel motor is higher than the upper limit value of the temperature, the front and rear distribution ratio is changed within a range in which excessive slip does not occur at the front wheels, the rear wheel plan driving force is recalculated, and the automatic driving of the vehicle is implemented taking the rear wheel plan driving force as a target driving force.

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.

A driving force distribution control system for a four-wheel drive vehicle is provided. The four-wheel drive vehicle uses front wheels as main driving wheels, and when a towed vehicle is coupled to a coupling part provided to a rear part of the four-wheel drive vehicle, the towed vehicle has the center of gravity position so that a downward load in a vehicle up-and-down direction is applied to the rear part of the vehicle through the coupling part. A driving force distribution control device includes a towing determination module configured to determine whether the vehicle is towing the towed vehicle, and when it is determined that the vehicle is towing the towed vehicle, a driving force distribution control device controls the driving force distributing device so that the driving force distributing amount to rear wheels becomes larger than that when the four-wheel drive vehicle is not towing the towed vehicle.

A driving force distribution control system for a four-wheel drive vehicle is provided. The four-wheel drive vehicle uses front wheels as main driving wheels, and when a towed vehicle is coupled to a coupling part provided to a rear part of the four-wheel drive vehicle, the towed vehicle has the center of gravity position so that a downward load in a vehicle up-and-down direction is applied to the rear part of the vehicle through the coupling part. A driving force distribution control device includes a towing determination module configured to determine whether the vehicle is towing the towed vehicle, and when it is determined that the vehicle is towing the towed vehicle, a driving force distribution control device controls the driving force distributing device so that the driving force distributing amount to rear wheels becomes larger than that when the four-wheel drive vehicle is not towing the towed vehicle.

A vehicle driving-force distributing device includes: first connecting/disconnecting teeth disposed on the inner circumferential side of the ring gear; a connecting/disconnecting mechanism that includes a cylindrical member and a connecting/disconnecting sleeve including second connecting/disconnecting teeth and spline-fitted movably in the rotation axis direction and relatively non-rotatably to the outer circumferential side of the shaft insertion portion and that connects and disconnects a power transmission path between the ring gear and the differential case by moving the connecting/disconnecting sleeve in the rotation axis direction between a meshing position at which the second connecting/disconnecting teeth are meshed with the first connecting/disconnecting teeth and a non-meshing position at which the second connecting/disconnecting teeth are not meshed with the first connecting/disconnecting teeth; and a synchronizing mechanism disposed between the ring gear and the cylindrical member and reducing a relative rotation between the first connecting/disconnecting teeth and the second connecting/disconnecting teeth.