Working principle of pilot solenoid valve

The picture shows the pilot solenoid valve, which is composed of the pilot valve and the main valve. The two are connected by a channel. When the solenoid valve coil is energized, the moving iron core and the static iron core are pulled together to open the pilot valve hole, and the pressure in the back cavity of the valve core passes The pilot valve hole flows to the outlet. At this time, the pressure in the back cavity of the valve core is lower than the inlet pressure. The pressure difference is used to separate the valve core from the main valve port, and the medium flows from the inlet to the outlet. When the coil is de-energized, the moving iron core is separated from the static iron core, and the pilot valve hole is closed. The pressure in the back cavity of the valve core is gradually supplemented by the inlet pressure and balances with the inlet. The valve core closes the valve tightly due to the spring force.

Pilot-type solenoid valve such as: ZCB, ZCZP, ZCGL

Pilot diaphragm solenoid valves such as: ZCA, ZCS

Features: low power consumption, large diameter, simple structure and arbitrary installation direction, but only for occasions where there is a certain pressure difference across the solenoid valve.

The solenoid valve is a widely used control element in the aerospace field. A pilot-operated two-way solenoid valve is a two-position five-way structure with two chambers, normally open and normally closed. It switches the opening and closing of downstream gas equipment through gas flow. Due to the complicated structure of the solenoid valve and the gas channel, during use, it is found that different individuals of the same solenoid valve will exhibit different pressure building processes. Because the pressure build-up pressure of the normally open cavity and the normally closed cavity of the solenoid valve (no special instructions, the pressure in this article refers to gauge pressure) and the pressure build-up time may have a greater impact on the downstream gas equipment, it needs to be deepened analysis.

Pilot two-way solenoid valve is mainly composed of valve body, normally closed main valve flap, normally open main valve flap, pilot valve flap, electromagnet and other parts. The main valve flap and the piston are connected by a plunger (Figure 1) .Its characteristic is that there is no elastic reset element such as a spring inside, which completely switches the air passages by aerodynamic force and electromagnetic force, and controls the supply of air between the normally open cavity and the normally closed cavity. Sealed, the maximum working pressure is 5.0MPa.

When the electromagnet is in the power-off state, the inlet gas is divided into two channels, one directly acts on the normally open main valve flap to open it, the solenoid valve normally opens the cavity B to supply gas, and the other acts on the pilot valve flap and along the gas The channel enters the normally closed control chamber F, which seals the normally closed main valve flap. When the electromagnet is energized, the pilot valve flap closes, the gas in the normally closed control chamber F is discharged into the atmosphere from the bleed port D, the pressure in the normally closed control chamber F is released, the normally closed main valve flap opens, and the solenoid valve normally closed chamber C supplies gas. At the same time, the gas will also enter the normally open control chamber E along the gas channel, pressing the normally open main valve flap tightly and sealing it.

1. Valve body 2. Normally open main valve flap 3. Diaphragm 4. Pilot valve flap 5. Electromagnet 6. Normally closed main flap

A-Air inlet B-Normally open chamber C-Normally closed chamber D-Air bleed port E-Normally open control chamber F-Normally closed control chamber G-Normally open control chamber bleed port H-Normally closed control chamber bleed port

(a) Power-off state (b) Power-on state

Figure 1 Pilot operated two-way solenoid valve

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