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.

The present disclosure provides an electronic stability control method for a vehicle for performing vehicular electronic stability control simply by adjusting driving force and braking power that are generated by a driving device of the vehicle without use of a driving force distributing method between front, rear, left, or right vehicle wheels. To this end, the vehicular electronic stability control method includes determining a vehicular state value indicating a driving state of a vehicle from information collected from the vehicle, comparing the determined vehicle state value with a first reference value, and controlling an operation of a driving device for generating driving force for driving the vehicle by the controller when the vehicle state value is greater than the first reference value to adjust driving force for preventing understeer or oversteer of the vehicle.

A sensor abnormality determination device of a four-wheel drive vehicle including a drive source, main drive wheels and sub-drive wheels, a power transmitting member, a first connecting/disconnecting device, a second connecting/disconnecting device, a first sensor, and a rotation sensor, the sensor abnormality determination device comprises a first sensor abnormality determining portion determining that the first sensor is abnormal when the rotation sensor detects the rotation of the power transmitting member and it is presumed that the four-wheel drive vehicle is in the four-wheel drive state, when the first sensor detects that the first connecting/disconnecting device is in the disconnecting state, and when the rotation sensor detects the rotation of the power transmitting member after the second connecting/disconnecting device is switched to the disconnecting state.

A vehicle orientation control device is provided in a four wheel drive vehicle capable of applying braking and driving force to each of the vehicle wheels. The vehicle orientation control device (24) is provided in a vehicle control device (10) for controlling the four wheel drive vehicle and includes a standard yaw rate calculating unit (25), a yaw rate sensor (22), a target yaw moment calculating unit (26), a braking and driving force commanding unit (15), and a yaw moment control unit (27). The yaw moment control unit (27) includes an allocation ratio varying unit (27a) for continuously changing the front and rear allocation ratio of the yaw moment control torque to be distributed to the front and rear wheels (3) and (2) in dependence on the detected actual yaw rate that is detected by the yaw rate sensor (22).

A traction control device and method for a four-wheel drive electric vehicle are disclosed. When the drive wheels of an electric vehicle spin, a drive force of the electric vehicle is controlled so as to restrain the spinning of the drive wheels and to secure the starting performance and acceleration performance of the electric vehicle.

A method for decelerating a vehicle includes actuating an electric brake motor of an electromechanical braking mechanism in an event of a failure of a hydraulic vehicle brake to produce a braking force in an event of a failure of the hydraulic vehicle brake. The method further includes producing a decelerating torque in the drive train of the vehicle in the event of the failure of the hydraulic vehicle brake. The vehicle includes a brake system. The brake system has the hydraulic vehicle brake and the electromechanical braking mechanism with the electric brake motor.

A wheel load estimation method of a four-wheel drive vehicle driven by a rotational driving device comprises a correlation relationship setting step for previously setting a correlation relationship between a total weight and at least one of the front wheel load and the rear wheel load by variously changing a movable load of the vehicle, a total vehicle weight computation step for calculating a current total vehicle weight from an output torque of the rotational driving device and a longitudinal acceleration of the vehicle corresponding to the output torque, and a wheel load estimation step for estimating the wheel load of at least a driving wheel from the correlation relationship and the total vehicle weight.

A hybrid powertrain includes a torque provider, an automatic transmission without a torque converter, and a transfer case configured for providing four wheel drive low range. A controller receives a signal indicative of the transfer case being in low range and determines if brake pedal torque is indicative of a brake pedal being released and, if so, commands engagement of a launch clutch of the transmission up to maximum creep torque capacity at a predetermined maximum gradient. The controller determines when torque provider speed is synchronized with vehicle creep speed, and upon such determination, controls the launch clutch to fully engage to a lock up state to mimic behavior of engagement of a manual transmission gear when the hybrid powertrain is in low range to thereby substantially eliminate a time lag associated with automatic transmissions having a torque converter or a constantly slipping launch clutch.

A vehicle includes a first axle temporary driven by a motor, a second axle permanently connected to the motor via a propeller shaft, and a sub-shaft that connects the propeller shaft and the first axle. A control system for a connection between the motor and the first axle includes a first clutch between the propeller shaft and the sub-shaft, a second clutch between the sub-shaft and the first axle. The first clutch is controlled to continue applying a synchronous torque until the second clutch is determined to be connected. The second clutch is controlled to be connected in response to a determination that the second clutch is connectable.

The control device of a four-wheel drive vehicle is applied to a four-wheel drive vehicle having a differential restriction device which can change a differential restriction degree between a front wheel rotary shaft and a rear wheel rotary shaft, a braking device can separately change a braking force of the front wheels and a braking force of the rear wheels. The control device determines whether a specific state which has a high possibility that a state where a rear wheel slip ratio becomes larger than a front wheel slip ratio is generated occurs assuming that the differential restriction degree is set to a first degree when the differential restriction degree is set to a second degree so as not to allow the differential operation and change the differential restriction degree from the second degree to the first degree when it is determined that the specific state has occurred.