Micro vacuum pump is a compact instrument with one suction nozzle and one exhaust nozzle, which can continuously form vacuum or negative pressure at the inlet and form micro-positive pressure at the exhaust nozzle with the working medium of gas.
In practice, customers often need to change the direction of air flow in the pipeline. For example, the customer may hope to realize suction and exhaust alternately in one pipe. Actually, it’s easy to complete in a positive pressure pipeline system, only one two-position four-way solenoid valve can realize the function.
However, all the two-position four-way solenoid valves available on the market can’t work normally in the vacuum pipeline. How to solve it? In fact, some users have used the combination of four two-position two-way (2/2-way) solenoid valves (one of them is the air circuit on-off switch) to realize the function of the two-position four-way solenoid valve.

The hydraulic system can be divided into power elements, actuators, control elements, auxiliary elements and working medium. The solenoid valve is controlled by electromagnet, which is one kind of hydraulic valve, as a commonly used control component.
Generally, a solenoid valve has two or more working positions. One is the normal working position, namely the position of spool without an operation force. The middle position in the above symbol graphy is the normal position of the three-way pneumatic solenoid valve, simply speaking, it' s also the initial position of valve when it' s not powered on or hasn' t started to operate. The normal position of a two-position pneumatic solenoid valve with spring reset is the connection state in the frame near the spring. When drawing a system diagram, the oil/gas lines should generally be connected to the normal position of the pneumatic solenoid valve.

The working principle of PLC controlling the solenoid valve is that output module of PLC switch value is connected to the coil end of the solenoid valve. When the corresponding point of the module has a voltage output, the solenoid valve coil is powered on and the contacts are attracted. When there is no voltage output, the coil is powered off and the contacts separate.

Solenoid valve is composed of solenoid coil and magnetic core as well as a valve body with one or more holes. When the coil is energized or de-energized, the operation of magnetic core will cause the fluid to pass through the valve body or be cut off, thus changing the direction of fluid. The solenoid part of solenoid valve is composed of fixed iron core, moving iron core, coil and other parts. The valve body is composed of slide spool, slide valve sleeve and spring base. The solenoid coil is directly mounted on the valve body, and the valve body is sealed in the sealing pipe to form a simple and compact combination. The common solenoid valves in air separation include two-position three-way (3/2) solenoid valve, two-position four-way (4/2) solenoid valve and two-position five-way (5/2) solenoid valve.