3 Way 2 Position Pneumatic Solenoid Valve for Single Acting Cylinder

Solenoid valves are usually used on mechanical control and industrial valves. The position of the valve core is controlled by an electromagnetic coil. The air source is cut off and pass through, realizing the change the direction of fluid flow and then switching on and off of the valve. The following is a brief introduction of 2 position 3 way pneumatic solenoid valve to control the single acting cylinder. From this, we can have a better understand how a 3/2-way pneumatic solenoid valve work.

Introduction of 3/2 way pneumatic solenoid valve

The two-position three-way pneumatic solenoid valve has two positions and three ways. Two positions means that there are 2 positions of the valve core. Three ways, has 3 ports, namely, a air inlet, a working port (air outlet) and a exhaust port. The pneumatic solenoid valve can be divided into normally open and normally closed. The figure below shows a 3/2-way normally closed pneumatic solenoid valve, with a air inlet (P), two air outlets (A/B).  When the solenoid valve is powered on, P and A are connected. P and B are connected when the solenoid valve is powered off.
3/2 way solenoid valve for single-acting cylinder

The single-acting air cylinder is to add the spring to one end of the piston. When there is no compressed air, the piston just suffers the spring force from one side, so it maintains on one position. When compressed air is pumped into the other side of the piston, the piston moves to the direction with the spring after the pressure of the compressed air overcomes the force of the spring. After that, the spring is compressed. When the piston suffers the tension of the spring, the movement is generated and recovers to the primitive state. Repeatedly control the ventilation and leakage at one side of the piston to finish repeated movement of the air cylinder. It should be noted that, no matter which side of the piston suffers the pressure, the side not suffering the pressure must be connected with the air. In this way, the piston can pump out the air within the chamber during the process of movement. The single-acting air cylinder is usually controlled by 2-position and 3-port solenoid valve.

1. Initial state
The solenoid valve is normally-closed, which is at a state of electric supply. The single-acting air cylinder piston functions on the left of the air cylinder via the spring. The single-acting air cylinder is generally controlled by the two-position and three-port solenoid valve. See Fig. 1.

2. Working state
When the solenoid valve gains electricity, the solenoid valve P port and A port are connected with power. The air source flows from A port into the air cylinder, and the air cylinder piston moves to the right. See Fig. 2 below.

3. Power-off state
When the solenoid valve losses electricity, the solenoid valve A port and R port are connected with power. The air cylinder discharges air via the solenoid valve, and the piston returns to the left under the action of the spring. See Fig. 1.