Classification of solenoid valves

Classification of solenoid valves

Direct acting solenoid valve

　　 Introduction:

　　There are two types: normally closed and normally open. The normally closed type is closed when the power is cut off. When the coil is energized, electromagnetic force is generated, so that the moving iron core overcomes the spring force and attracts the static iron core to directly open the valve, and the medium is in a path; when the coil is powered off, the electromagnetic force disappears and the moving iron The core is reset under the action of the spring force, and the valve port is directly closed, and the medium is blocked. The structure is simple, the action is reliable, and it works normally under zero pressure difference and micro vacuum. Normally open type is just the opposite. Such as a solenoid valve with a flow diameter smaller than φ6.

　　 principle

　　 When the normally closed type is energized, the solenoid generates electromagnetic force to lift the open part from the valve seat, and the valve opens; when the power is off, the electromagnetic force disappears, and the spring presses the open part on the valve seat and the valve opens. (Normal open type is the opposite of this)

　　 Features

　　 It can work normally under vacuum, negative pressure and zero pressure, but the diameter generally does not exceed 25mm.

　　 Step-by-step direct-acting solenoid valve

　　 Introduction

　　 This kind of valve adopts the primary opening valve and the secondary opening valve to be connected in one body. The main valve and the pilot valve make the electromagnetic force and the pressure difference directly open the main valve port in steps. When the coil is energized, electromagnetic force is generated to make the moving iron core and the static iron core attract, the pilot valve port is opened and the pilot valve port is set on the main valve port, and the moving iron core and the main valve core are connected together, at this time the main valve is on The pressure of the cavity is unloaded through the pilot valve port, and the main valve core moves upward under the simultaneous action of the pressure difference and the electromagnetic force, and the medium flow of the main valve is opened. When the coil is de-energized, the electromagnetic force disappears. At this time, the movable iron core closes the pilot valve hole under the action of its own weight and spring force. At this time, the medium enters the upper cavity of the main valve core in the balance hole to increase the pressure in the upper cavity. The main valve is closed under the action of spring return and pressure, and the medium is cut off. The structure is reasonable, the action is reliable, and it works reliably even at zero pressure difference. Such as: ZQDF, ZS, 2W, etc.

　　 principle

　　 It is a principle of combining direct action and pilot type. When there is no pressure difference between the inlet and the outlet, the electromagnetic force directly lifts the pilot small valve and the main valve closing member upwards in turn, and the valve opens. When the inlet and outlet reach the starting pressure difference, after power on, the electromagnetic force pilots the small valve, the pressure in the lower chamber of the main valve rises, and the pressure in the upper chamber drops, so that the pressure difference pushes the main valve upward; when the power is off, the pilot valve uses a spring The force or medium pressure pushes the closing piece and moves downward to close the valve.

　　 Features

　　 can also operate under zero pressure difference, vacuum or high pressure, but the power is large, and it must be installed horizontally.

　　Indirect pilot solenoid valve

　　 Introduction

　　 This kind of solenoid valve is formed by connecting the pilot valve and the main valve core to form a channel combination; the normally closed type is closed when it is not energized. When the coil is energized, the generated magnetic force causes the moving iron core and the static iron core to attract, the pilot valve port opens, and the medium flows to the outlet. At this time, the pressure in the upper cavity of the main valve core decreases and is lower than the pressure on the inlet side, forming a pressure difference to overcome the spring The resistance moves upwards to achieve the purpose of opening the main valve port and the medium flows. When the coil is de-energized, the magnetic force disappears and the movable iron core resets and closes the pilot port under the action of the spring force. At this time, the medium flows in from the balance hole, the pressure in the upper cavity of the main valve core increases, and moves downward under the action of the spring force. Close the main valve port. The principle of normally open is just the opposite.

　　 principle

When energized, the electromagnetic force opens the pilot hole, the pressure in the upper chamber drops rapidly, and a high pressure difference is formed around the open part. The fluid pressure pushes the open part to move upward and the valve opens; when the power is off, the spring force opens the pilot hole , The inlet pressure quickly passes through the bypass hole to form a low and high pressure difference around the valve closing member, and the fluid pressure pushes the opening member to move downwards to open the valve.

　　 Features

　　Small volume, low power, high fluid pressure range upper limit, can be installed arbitrarily (need to be customized) but must meet the fluid pressure difference conditions.