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Proportional solenoid valve working principle introduction explanation

The flow control valve is a proportional solenoid valve, which is based on the principle of electromagnetic switch valve: When power is off, the spring presses the iron core directly on the valve seat and closes the valve. When the coil is energized, the resulting electromagnetic force lifts the core against the force of the spring, opening the valve. The proportional solenoid valve makes some changes to the structure of the solenoid switch valve: it balances the spring force with the electromagnetic force at any coil current. The size of the coil current or the magnitude of the electromagnetic force will affect the plunger stroke and valve opening, and the ideal linear relationship between the valve opening (flow) and the coil current (control signal).
Direct-flow proportional solenoid valve flow is under the valve seat. The medium flows in from below the valve seat, and its direction of force is the same as that of the electromagnetic force, which is opposite to the force of the spring. Therefore, it is necessary to set the maximum and minimum flow values corresponding to the working range (coil current) in the working state. Dendro's proportional solenoid valves are closed when power is off (NC, normally closed).
If the plunger and plunger stopper geometry are both flat, the electromagnetic force will drop too much as the air gap increases, making the valve useless as a regulating valve. Only by designing the plunger and the plunger stopper as a special structure can the spring force and the electromagnetic force be balanced under different coil current values. The outside of the stopper was designed to be tapered, and the top of the plunger was designed as a fully mirrored bevel. When power is off, the spring force closes the valve. The seal integrated in the bottom of the plunger ensures that the valve is leak-free.
The plunger moves in the valve guided by the guide pin (top) and flat spring (bottom). The more flexible the plunger slides over the coil, the higher the response sensitivity and the better the repeatability of the control position. Because in addition to electromagnetic force and spring force, there is a third kind of unavoidable force: friction. Friction can interfere with control characteristics. However, as long as the plunger is accurately guided and special electronic control is used, the friction force can be greatly reduced.

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