Working principle of solenoid valves

1. Assembly and Classification of Solenoid Valves

I. Classification by Control Method

1. Normally Closed Type: The air circuit is closed when the coil is de-energized.

2. Normally Open Type: The air circuit is open when the coil is de-energized.

3. Self-Holding Type: After the coil is energized, the solenoid valve opens and remains open even when the power is cut off. After the coil is energized, the solenoid valve closes and remains closed even when the power is cut off.

II. Classification by Operation Method

Direct-Acting Type

1. Coil 2. Magnetic Isolation Tube 3. Valve Core 4. Spring 5. Seal 6. Valve Body

Pilot Diaphragm Type

1. Coil 2. Magnetic Isolation Tube 3. Valve Core 4. Spring 5. Seal 6. Valve Body 7. Diaphragm 8. Spring 9. Pilot Hole 10. Valve Cover

Step-by-Step Direct-Acting Type

It adopts a combined principle of direct-acting and pilot-operated. When there is no pressure difference between the inlet and outlet, the electromagnetic force directly lifts the pilot valve and the main valve closing part upward in sequence after energization, opening the valve. When the start-up pressure difference is reached between the inlet and outlet, the electromagnetic force acts on the pilot valve after energization. The pressure in the lower chamber of the main valve rises while the pressure in the upper chamber drops, pushing the main valve upward by means of the pressure difference. When de-energized, the pilot valve uses spring force or medium pressure to push the closing part downward, closing the valve.

2/2-Way Solenoid Valve

2-way solenoid valve: The valve body has one inlet and one outlet connected to the pipeline. It is a one-way valve and shall be used in the direction of the arrow (one inlet and one outlet).

3/2-Way Solenoid Valve

The valve body has three ports connected to the pipeline and two holes, which can be used in three control modes:

• Normally Closed Type: The pressure port is closed and the exhaust port is connected to the cylinder port when de-energized; the pressure port is connected to the cylinder port and the exhaust port is closed when energized.

• Normally Open Type: The pressure port is connected to the cylinder port and the exhaust port is closed when de-energized; the pressure port is closed and the cylinder port is connected to the exhaust port when energized.

• Universal Type: Allows the valve to be connected as either a normally closed or normally open position.