Automotive Solenoid Valve Working Principle
The working principle of an automotive solenoid valve is as follows: when energized, the electromagnetic coil generates electromagnetic force to lift the closing element from the valve seat, opening the valve; when de-energized, the electromagnetic force disappears, and the spring presses the closing element back onto the valve seat, closing the valve.
There are three types of solenoid valves, as follows:
1. Distributed Direct-Acting Solenoid Valve: This combines direct-acting and pilot-operated principles. When there is no pressure difference between the inlet and outlet, energizing directly lifts the pilot valve and the main valve closing element sequentially, opening the valve. When the inlet and outlet reach the starting pressure difference, energizing actuates the pilot valve, increasing the pressure in the lower chamber of the main valve and decreasing the pressure in the upper chamber, thus using the pressure difference to push the main valve open. When de-energized, the pilot valve uses spring force or medium pressure to push the closing element downwards, closing the valve.
2. Direct-Acting Solenoid Valve: When energized, the electromagnetic coil generates electromagnetic force to lift the closing element from the valve seat, opening the valve; when de-energized, the electromagnetic force disappears, and the spring presses the closing element back onto the valve seat, closing the valve.
3. Pilot-operated solenoid valve: When energized, the electromagnetic force opens the pilot orifice, causing the pressure in the upper chamber to drop rapidly. This creates a pressure differential around the closing element, with the pressure lower at the top and higher at the bottom. The fluid pressure pushes the closing element upward, opening the valve. When de-energized, the spring force closes the pilot orifice. The inlet pressure quickly passes through the bypass orifice, creating a pressure differential around the closing element, with the pressure lower at the bottom and higher at the top. The fluid pressure pushes the closing element downward, closing the valve.
