Abstract: A power distribution control system system takes a strategy for adjusting power distribution to vary control mode in order to avoid influence of variation of wheel speed difference between a primary driving wheel directly or permanently connected to a vehicular prime mover, i.e. an automotive internal combustion engine and thus having greater inertia and an auxiliary driving wheel having smaller inertia. For this, occurrence of hunting in power distribution control is detected. As long as hunting is not detected, the wheel speed difference dependent power distribution control mode is selected for controlling power distribution depending upon a wheel speed difference between the primary and auxiliary wheels.

Abstract: A driving force distribution control device for a four wheel drive vehicle comprises first computing means for computing a clutch engaging force using a rotational speed differential between front and rear wheels, second computing means for computing a clutch engaging force using only a vehicle speed and third computing means for computing a target clutch engaging force form the sum of the clutch engaging forces computed by the first and second computing means. A transfer clutch variable in engagement for controlling distribution of a driving force to the front and rear wheels is brought into engagement with the target clutch engaging force.

Abstract: A driving force distribution control system for a 4WD vehicle includes a transfer clutch for continuously varying a front wheel driving force transmitted to front wheels, a sensor group for sensing conditions of the vehicle to determine a vehicle speed, and a front and rear wheel speed difference obtained by subtracting a front wheel speed from a rear wheel speed, and a control unit for controlling the front wheel driving force substantially continuously by controlling the engagement force of the transfer clutch.

Abstract: A control system for controlling a driving torque distribution between front and rear axles of a four wheel drive vehicle includes a transfer clutch capable of continuously varying a torque transmitted to the front axle, front and rear wheel speed sensors for determining a front and rear wheel speed difference, a sensor for directly or indirectly sensing a lateral acceleration of the vehicle and a control unit. The control unit controls the transfer clutch in a characteristic such that the torque transmitted to the front axle is increased continuously and monotonically with an increase of the wheel speed difference at a steep rate when the lateral acceleration is low, and at a gradual rate when the lateral acceleration is high.

Abstract: A driving force distribution control system for a 4WD vehicle includes a transfer clutch for continuously varying a front wheel driving force transmitted to front wheels, a sensor group for sensing a front wheel speed, a rear wheel speed and a vehicle speed, and a control unit for continuously controlling the front wheel driving force by controlling the engagement force of the transfer clutch. The control unit is arranged to vary the driving force distribution from a 2WD mode toward a 4WD mode in accordance with a front and rear wheel speed difference when the front wheel speed is higher than the rear wheel speed, and at the same time the vehicle speed is higher than a predetermined reference speed. Therefore, the control system can improve the stability of the vehicle during engine braking, and prevent tight corner braking at low vehicle speeds.

Abstract: A control system for a limited-slip differential gear unit is cooperative with a traction control system to provide better vehicle driving stability. The control system for a limited-slip differential gear unit is capable of optimizing driving torque transmission characteristics for improving cornering stability of the vehicle. The limited-slip differential gear unit control system, according to the invention, is operative in response to difference of wheel slippages at driven wheels for slip limiting force in order to adjust wheel slippage of heavier load driven wheel at a predetermined value. The control system is cooperative with a traction control system which is detective of wheel slippage due to wheel spinning caused by excessive driving torque to be applied to the driven wheels and adjusting the driving torque to be distributed to the driven wheels.

Abstract: A four wheel drive system of a vehicle has a multiple disc friction type transfer clutch capable of varying torque transmitted to front wheels, a hydraulic circuit for varying an engagement force of the transfer clutch by supplying a fluid pressure to the transfer clutch, front and rear wheel rotational speed sensors, a sensor for sensing a turning radius corresponding to a steering angle, and a control unit for varying the torque transmitted to the front wheels by sending a control signal to the hydraulic circuit in accordance with a front and rear wheel speed difference, a vehicle speed and the turning radius.

Abstract: A four wheel drive system has an interaxle multiple disc friction clutch, an actuator for varying torque transmitted through the clutch to a front wheel drive shaft by varying a clutch pressure of the clutch, first and second sensors for sensing rotational speeds of the front wheel and rear wheel drive shafts, a third element for producing a third signal, and a control unit for controlling a driving torque distribution between the front and rear wheel drive shafts by sending a control signal to the actuator. The control means increases the torque transmitted through the clutch with increase in a speed difference between the front wheel and rear wheel drive shafts in accordance with one of characteristics selected in accordance with the third signal. The third element is designed to find a condition of the vehicle which can be controlled by a driver of the vehicle, and may take the form of an accelerator position sensor or a manually operated selector switch.