Working Principle of Automobile Solenoid Valve
As the actuator of the electronic control system, the automobile solenoid valve plays a key role in many systems of the automobile. Its working principle is mainly based on the interaction between electromagnetic force and spring force.
Direct-acting solenoid valve principle: It is the most basic working form. When the solenoid valve is energized, the electromagnetic coil will generate electromagnetic force. The function of this electromagnetic force is to lift the closing part that was originally tightly fitted on the valve seat, so that the valve is open; once the power is off, the electromagnetic force disappears. At this time, the spring installed in the solenoid valve will play a role, relying on the spring force to press the closing part back to the valve seat again, so that the valve is closed. For example, in some simple oil or gas pipeline control, the direct-acting solenoid valve can directly control the on and off of the medium.
Distributed direct-acting solenoid valve principle: This is a structure that combines direct-acting and pilot types. When there is no pressure difference between the inlet and outlet, the electromagnetic force begins to play a role when the power is on. It not only directly drives the pilot small valve, but also makes the closing parts in the main valve be lifted up in turn, so as to realize the valve opening operation. This solenoid valve combines the advantages of direct-acting and pilot-operated types. It will perform better in some automotive control systems that require precise control and do not change much in system pressure.
Principle of pilot-operated solenoid valve: When powered on, the electromagnetic force will cause the pilot hole to be opened. In this way, the pressure in the upper chamber will drop rapidly, and a pressure difference will be formed around the closing part, where the upper pressure is lower than the lower pressure. Due to the pressure difference of the fluid, the closing part will be pushed upward, and the valve will eventually be fully opened; when the power is off, the spring force will cause the pilot hole to close, and the inlet pressure will quickly enter the chamber through the bypass hole, which will form a pressure difference around the closing part, so the fluid pressure will push the closing part downward and close the valve. This solenoid valve is used in some automotive systems that require high valve opening speed and fluid pressure control, such as the intake or exhaust system of the automotive engine, which can help achieve more precise flow and pressure control, thereby improving the overall performance of the engine.
Example of the working mechanism of the solenoid valve in the automotive system: In the idle control system of the automotive engine, the idle solenoid valve plays a vital role. When the engine is idling, the idle solenoid valve continuously adjusts its opening degree through the precise control of the computer (ECU). When it is necessary to maintain a lower idle speed, the ECU will control the solenoid valve to reduce the opening and limit the intake volume; if it is necessary to increase the idle speed, the ECU will control the solenoid valve to increase the opening and increase the intake volume. In order for the solenoid valve to accurately complete these operations, it relies on the various working principles mentioned above to achieve precise intake volume control and ensure that the engine maintains idle speed at the lowest stable speed, which can not only optimize fuel efficiency and emission performance, but also maintain the stability of engine operation.
