Four-wheel steering introduction
Four wheel steering (4WS) means that during the steering of the car, the four wheels can be deflected relative to the body at the same time according to signals such as the front wheel or driving speed. The rear wheel of the four-wheel steering car can be deflected in the same direction as the front wheel and can be deflected in the reverse direction, as shown in Figure 2.
If the steering of the rear wheel is the same as the steering direction of the front wheel, it is called the same direction control mode. The turning radius is larger than the turning radius of the two-wheel steering. When the car is driving above 40km/h, the rear wheel has a deflection angle of 2.5°. The utility model has the advantages that the deflection angle of the vehicle body and the traveling direction is small when the vehicle is turned, the rotation and the side slip of the vehicle when the vehicle is adjusted to the steering direction are reduced, the steering stability is improved, and the vehicle can be stably steered on the wet road surface.
If the steering of the rear wheel is opposite to the steering direction of the front wheel, it is called the reverse (reverse) control mode, and the turning radius is smaller than the turning radius of the two-wheel steering. At low speeds, the rear wheel has a reverse deflection angle of up to 5°, which is suitable for cars entering the garage and turning at narrow corners. As the vehicle speed increases, the steering angle of the rear wheels becomes smaller, and the steering angle becomes 0° when the vehicle speed reaches 40 km/h. This increases the mobility of the car to park or turn in tight spaces.
The four-wheel steering system works in mechanical, hydraulic and electric modes.