In the existing market, the power steering system can be roughly divided into three categories: mechanical hydraulic power steering system, electronic hydraulic power steering system and electric power steering system.
Mechanical hydraulic power steering system
Mechanical hydraulic power steering system generally consists of hydraulic pump, oil pipe, pressure flow control valve body, V-shaped transmission belt, oil storage tank and other components.
This system works regardless of whether the car is turning or not, and when the high steering speed is low, the hydraulic pump needs to output more power to obtain a larger boost. Therefore, resources are also wasted to some extent. Moreover, due to the high pressure of the hydraulic pump, it is also relatively easy to damage the power assist system.
In addition, the mechanical hydraulic power steering system consists of a hydraulic pump and a pipeline and a cylinder. To maintain the pressure, regardless of whether or not steering assistance is required, the system is always in a working state and has high energy consumption, which is also a cause of resource consumption.
In general, economical cars use more mechanical hydraulic power assist systems.
Electro-hydraulic power steering system
Main components: oil storage tank, power steering control unit, electric pump, steering gear, power steering sensor, etc., wherein the power steering control unit and electric pump are a whole structure.
Working principle: The electro-hydraulic steering assist system overcomes the shortcomings of the traditional hydraulic steering assist system. The hydraulic pump used is no longer driven directly by the engine belt, but an electric pump. All the working conditions are calculated by the electronic control unit according to the driving speed and steering angle of the vehicle. Simply put, at low speed and large steering, the electronic control unit drives the electronic hydraulic pump to output high power at high speed, which makes the driver save direction; when the car is driving at high speed, the hydraulic control unit drives the electronic hydraulic pump at a lower speed. Operation, while not affecting the need for high-speed steering, while saving part of the engine power.
Electric Power Steering System (EPS)
The English full name is Electronic Power Steering (EPS), which uses the power generated by the electric motor to assist the driver in power steering. The composition of EPS, different cars, although the structural components are not the same, but generally similar. It is generally composed of a torque (steering) sensor, an electronic control unit, a motor, a speed reducer, a mechanical steering gear, and a battery power source.
Main working principle: When the car is turning, the torque (steering) sensor will “feel” the torque of the steering wheel and the direction of the intended rotation. These signals will be sent to the electronic control unit through the data bus. The electronic control unit will according to the transmission torque. The data signal, such as the direction of the intended rotation, sends an action command to the motor controller, so that the motor outputs a corresponding amount of rotational torque according to the specific needs, thereby generating a power steering. If you don't turn, the system will not work, and it will wait in the standby state. Due to the working characteristics of electric power steering, you will feel that driving such a car, the sense of direction is better, and the speed is more stable at high speed, that is, the direction is not floating. And because it doesn't work when it doesn't turn, it also saves energy. In general, high-end cars use such power steering systems.