Abstract: An improvement is provided in a differential gear which includes an input shaft, a differential casing adapted to be rotated by the input shaft, a differential pinion shaft radially extending within the differential casing and a plurality of differential pinion gears rotatably mounted on the differential pinion shaft. A pair of side gears having a rotation axis common to that of the differential casing and meshing with the pinion gears, and a pair of output shafts fixed to the side gears. The improvement comprises a centrifugal weight member slidably mounted on the differential pinion shaft and radially inwardly biased, and a multiple disc clutch provided between the differential casing and the output shafts. The clutch is adapted to be engaged in response to the radially outward movement of the centrifugal weight member.

Abstract: A differential device using a fluid includes a differential case and a pair of sleeves which are rotatably supported by the differential case. Each of the outer end portions of the sleeves is connectable to one of a pair of rotary output shafts, while the inner end portions of the same are protruded into the case to face each other with a small clearance left therebetween. A chamber to be filled with a viscous liquid is defined between the case and the sleeves. A plurality of drive plates which are rotatable integrally with the case and a plurality of driven plates which are rotatable integrally with the sleeves are disposed in the chamber alternately with each other and in an overlapping manner. Guide rings are interposed between the nearby driven plates to position them at equally spaced locations.

Abstract: Disclosed is an actuator for steering the rear wheels in front and rear wheel steering device for vehicle in which the external forces, such as the self aligning torque of the rear wheels and irregularities of the road surface, which may be applied to the rear wheels are prevented from being transmitted to the actuator for controlling the steering angle of the rear wheels. Thereby, the steering angle of the rear wheels are determined solely by the control action of the front and rear wheel steering device and the motion of the vehicle is not affected by external forces. As a result, the vehicle motion is stabilized. When the force for steering the front wheels is transmitted to the rear wheels to steer them, elimination of the reaction from the road to the actuator prevents undesirable variation in the force required to steer the vehicle or the force required to hold a steering angle.

Abstract: In a front and rear wheel steering device for a vehicle in which the steering angle ratio of the rear wheels relative to the front wheels is variable according to the vehicle speed, by accounting for the magnitude of vehicle acceleration in determining the steering angle ratio of the rear wheels by using a mathematical function in the form of f(u) - g(u')where u is a vehicle speed and u' is a change rate of the vehicle speed, it is possible to reduce the slip angle of the vehicle to zero irrespective of the vehicle speed and the vehicle acceleration and the phase delay of the lateral response of the vehicle can be reduced, whereby the driveability of the vehicle is substantially improved and, thus, driving a car can be made easier, safer and less tiring.

Abstract: The front and rear wheel steering device of the present invention not only has a means for allowing the manual selection of a mathematical function which determines the steering angle ratio of the rear wheels relative to the front wheels from a plurality of mathematical functions but also has a means for limiting such a manual selection depending on the condition of the vehicle. Since manual selection of a mathematical function for the steering angle ratio may not be appropriate under certain vehicle conditions, the device of the present invention limits such a manual selection when the vehicle speed, the vehicle acceleration, the shift position of the transmission, the steering speed or the steering acceleration is greater than a certain value. Thereby, the convenience of the manual selection of the steering angle ratio is preserved yet any undesirable vehicle response from improper manual selection of the steering angle ratio is prevented.

Abstract: An actuator for steering the rear wheels in front and rear steering device for a vehicle in which the steering angle of the rear wheels can be manually neutralized should the actuator fail with the rear wheels steered to a certain angle. The actuator may be a type which either directly steers the rear wheels following command from control means or varies the state of means for setting up the steering angle ratio of the rear wheels. In either case, a preferably detachable handle may be engaged to an output end of power means of the actuator. Thus, the situation in which the rear wheels are frozen at a certain steering angle and the driving of the vehicle becomes difficult is safely avoided.

Abstract: A front and rear wheel steering device which varies the steering angle ratio of rear wheels relative to the steering angle of front wheels in relation with vehicle speed is utilized to improve the drive response of a vehicle, as well as to improve the maneuverability of the vehicle. By varying the steering angle ratio which is a function of vehicle speed according to the running condition of the vehicle, the interference of the running condition of the vehicle upon the driving response can be reduced. The driving response may be evaluated in terms of yaw rate or lateral acceleration of the vehicle for a certain steering input. The running condition of the vehicle may comprise any combination of vehicle acceleration, friction between tires and the road surface, load acting between front wheels and the road surface, and load acting between rear wheels and the road surface.

Abstract: In a front and rear wheel steering device for a vehicle in which the steering angle ratio of the rear wheels relative to the front wheels is variable according to the vehicle speed, by accounting for the magnitude of vehicle acceleration in determining the steering angle ratio of the rear wheels by selecting a mathematical function from a plurality thereof, the vehicle response particularly in high speed range can be improved. Smooth transition from a certain characteristics to another may be achieved either by preparing a number of mathematical functions of vehicle speed for the steering angle ratio of the rear wheels or providing some time delay in the transition from one characteristics to another, preferably in proportion to the magnitude of the vehicle acceleration.

Abstract: In a front and rear wheel steering device contive for vehicle in which the steering angle ratio of the rear wheels relative to the front wheels is variable according to the vehicle speed, provision of a manual selection means for fixing the steering angle ratio to certain fixed values which may be either positive or negative can greatly improve the maneuverability of the vehicle in both high speed and low speed ranges. However, inadvertent manual selection of the steering angle ratio is not desirable since it may cause a sudden change in the steering angle of the rear wheels. Therefore, this invention provides means for preventing the manual selection of the steering angle ratio when it is not proper. This means may be an active prohibition control of manual steering angle ratio selection means, an alarm to warn the driver or a vehicle speed control which limits the vehicle speed.

Abstract: In a front and rear wheel steering device for vehicle for variably controlling the steering angle ratio of rear wheels relative to the steering angle of front wheels according to a certain mathematical function of vehicle speed in such a manner that the rear wheels are steered in opposite phase relationship in a low speed range and in same phase relationship in a high speed range, by providing a selection means for manually selecting a special mathematical function for an extremely low speed range which will cause a same phase relationship at an extremely low speed and a smooth transition to the certain mathematical function, parking the car along a curbstone and changing the lateral position of the vehicle in a limited space are simplified since the rear part of the vehicle will not swing laterally.