Solenoid valves can be divided into the following types according to their working principles and structures:
Direct-acting solenoid valve: simple structure, directly using electromagnetic force to push the valve core to move. Suitable for low pressure and small flow occasions. When powered on, the electromagnetic force overcomes the spring force to lift the valve core and open the fluid passage; when powered off, the spring force presses the valve core back and closes the fluid passage.
Pilot-operated solenoid valve: complex structure, the pilot air pressure generated by the electromagnetic pilot valve pushes the main valve core to move. Suitable for high pressure and large flow occasions. When powered on, the electromagnetic pilot valve opens, the pilot air pressure pushes the main valve core to move, and the fluid passage is opened; when powered off, the pilot air pressure disappears, and the main valve core closes the fluid passage under the action of spring force or medium pressure.
Step-by-step direct-acting solenoid valve: combines the characteristics of direct-acting and pilot-operated solenoid valves. When the power is on, the electromagnetic force directly lifts the pilot small valve and the main valve closing parts upward in turn, and the valve opens; when the power is off, the pilot valve uses the spring force or the medium pressure to push the closing parts downward to close the valve.