Solenoid valve is an industrial equipment controlled by electromagnetism. It is an automatic basic component used to control fluid and belongs to actuator.
The pneumatic solenoid valve is one of them, which blocks or leaks different oil discharge holes by controlling the movement of the valve body, and the oil inlet hole is normally open, and the hydraulic oil will enter different oil discharge pipes, and then pass through. The oil pressure of the pneumatic solenoid valve pushes the piston of the oil cylinder, so that the mechanical movement of the entire solenoid valve is controlled by controlling the current of the electromagnet of the pneumatic solenoid valve.
This article mainly introduces the detailed content of the pneumatic solenoid valve and the solenoid valve. Let's take a look together.
Solenoid valve is several positions
According to the function and needs, the pneumatic solenoid valve has many channels and positions.
There are two-position two-way, two-position three-way, two-position five-way, two-position four-way, solenoid valve. (two-position five-way and two-position four-way are divided into single electric control and double electric control).
There are three-position and five-way; three-position and five-way are: middle-sealed three-position and five-way solenoid valve, medium-pressure three-position and five-way solenoid valve, middle-release three-position and five-way solenoid valve, and three-position and four-way solenoid valve. There are also four-position five-way solenoid valves (three solenoid heads) and so on for special needs.
Of course, the simplest and most commonly used are two-position three-way solenoid valves and two-position five-way solenoid valves.
The three-position five-way solenoid valve is only used when the cylinder (actuator) needs to stop in the middle.
Detailed explanation of several positions and several channels of solenoid valve (schematic diagram)
"Pass" and "position" are important concepts of pneumatic directional solenoid valves. Different "pass" and "position" constitute different types of pneumatic directional solenoid valves.
The so-called "two-position valve" and "three-position valve" mean that the spool of the reversing valve has two or three different working positions.
The so-called "two-way valve", "three-way valve" and "four-way valve" mean that there are two, three, and four valves on the valve body of the reversing valve that are not connected to each other and can be connected with different oil pipes or interfaces in the system. The oil passage/air passage can only be conducted through the switch of the valve port when the valve core is displaced.
The "several digits" in the front, you can say several digits depending on how many working states the valve has. If there are pneumatic component symbols, it will be easier to understand. The square on the symbol represents the valve body (there are arrows inside) or T-line) as many as a few. The following "jitong" means that there are several points on one of the squares (points that intersect with the arrow line and the T line), which is Jitong.
The meanings of graphic symbols are generally as follows:
(1) Use boxes to indicate the working position of the valve, and how many boxes there are to indicate how many "positions" there are;
(2) The arrow in the box indicates that the oil circuit is connected, but the direction of the arrow does not necessarily indicate the actual direction of the liquid flow;
(3) The symbol "┻" or "┳" in the box indicates that the passage is blocked;
(4) The number of interfaces connected to the outside of the box means how many "connections";
(5) Generally, the oil inlet/air inlet connecting the valve with the system oil supply circuit or air is represented by the letter p; the oil return/air return port connected between the valve and the system oil return circuit/air circuit is represented by t (sometimes o) Indicates; and the oil port/gas port connected to the valve and the actuator is represented by a, b, etc. Sometimes it is used on the graphic symbol to indicate the leakage oil port;
(6) The reversing valve has two or more working positions, one of which is the normal position, that is, the position where the spool is not subjected to the operating force. The middle position in the graphic symbol is the normal position of the three-position valve. The two-position valve utilizing the spring reset takes the channel state in the box close to the spring as its normal position. When drawing the system diagram, the oil circuit/air circuit should generally be connected to the normal position of the reversing valve.
(The picture below shows three-position four-way)
On-off, the five-way has five channels for ventilation, one of which is connected to the air source, two are connected to the air inlet and outlet of the external air chamber of the double-acting cylinder, and two are connected to the air inlet and outlet of the inner air chamber. The specific work The principle can refer to the working principle of the double-acting pneumatic actuator: on the air path (or liquid path), the two-position three-way solenoid valve has an air inlet (connected to the air source) and an air outlet (provided to the target Equipment air source), 1 exhaust hole (generally install a muffler, if you are not afraid of noise, you can not install it).
The two-position five-way solenoid valve has 1 air inlet (connected to the air source), 1 positive air outlet and 1 reverse air outlet (respectively provided to the target equipment with a positive and a negative air source), 1 There are 1 positive action exhaust hole and 1 reverse action exhaust hole (with muffler installed). For small automatic control equipment, the trachea generally uses 8-12mm industrial rubber trachea.
Electrically speaking, the two-position three-way solenoid valve is generally a single solenoid (that is, a single coil), and the two-position five-way solenoid valve is generally a double electric control (that is, a double coil). Coil voltage level generally adopts DC24V, AC220V and so on.
The two-position three-way solenoid valve is divided into two types: normally closed type and normally open type. The normally closed type means that the air circuit is broken when the coil is not energized, and the normally open type means that the air path is open when the coil is not energized.
The action principle of the two-position five-way double-electric control solenoid valve: when the positive action coil is energized, the positive action air circuit is connected (the positive action air hole has air), even if the positive action coil is powered off, the positive action air circuit is still connected , and will remain so until the reverse action coil is energized. When the reverse action coil is energized, the reverse action air circuit is connected (there is air in the air hole in the reverse action), even if the reverse action coil is powered off, the reverse action air circuit is still connected, and it will remain until the positive action coil is energized . This is equivalent to "self-locking".
Based on the characteristics of the two-position five-way dual-electric control solenoid valve, when designing the electromechanical control circuit or programming the PLC program, the solenoid valve coil can be activated for 1 to 2 seconds, which can protect the solenoid valve coil from damage .