An electromagnetic valve is an automatic control valve that uses an electromagnetic coil to attract the valve core when energized and reset when de-energized, thereby opening or closing air/liquid passages. Most are DC 6V, 12V, or 24V, and are often integrated with miniature air pumps, vacuum pumps, and water pumps to achieve automatic switching, reversing, and pressure relief of air and water flow. They are widely used in medical, beauty, and small pneumatic equipment.
Internal Structure: Composed of five parts: electromagnetic coil, moving iron core (valve core), spring, valve body, sealing gasket, and inlet/outlet ports.
Working Principle:
De-energized state: The spring holds the valve core in place, and the sealing gasket blocks the valve port, cutting off the flow of medium.
Electrified state: The coil generates magnetic force, overcoming the spring's tension to pull the valve core, opening the valve port and allowing air/liquid to flow freely.
De-energized state: The magnetic force disappears, the spring pushes the valve core back to its original position, sealing the valve port, closing the passage, and stopping the flow.
Normal open valve is the opposite: Normally open, closed when energized.
Main Categories
1. Two-way, two-position
Solenoid Valve (most widely used): One inlet and one outlet port, controlling only the flow of the pipeline. Used with vacuum pumps for negative pressure control and water pump control.
2. Two-way, three-position solenoid valve (standard in beauty/medical applications): One inlet, one outlet, and one vent port.
Power on: Inlet → Outlet, supplying air/operating under negative pressure.
Power off: Outlet → Vent, quickly depressurizing and releasing vacuum in the chamber.
Mostly used in blackhead removal devices and negative pressure therapy devices.
3. Miniature direct-acting solenoid valve: Compact size, rapid response (millisecond-level opening and closing), no pilot structure, can be driven at low pressure, suitable for built-in installation in small instruments.
