Solenoid valve

1.Whats is solenoid valve
Solenoid valve is an automatic basic element used to control fluid and belongs to actuator; Not limited to hydraulic and pneumatic. The solenoid valve is used to control the direction of hydraulic flow. The mechanical devices in the factory are generally controlled by hydraulic steel, so the solenoid valve will be used.
The working principle of the solenoid valve is that there is a closed cavity in the solenoid valve, and there are through holes in different positions. Each hole leads to different oil pipes. There is a valve in the middle of the cavity, and there are two electromagnets on both sides. The magnetic coil on which side energizes the valve body will be attracted to which side. By controlling the movement of the valve body, different oil drain holes will be blocked or leaked. The oil inlet hole is normally open, and the hydraulic oil will enter different oil drain pipes, Then the oil pressure pushes the piston of the oil cylinder, which drives the piston rod, and the piston rod drives the mechanical device to move. In this way, the mechanical movement is controlled by controlling the current of the electromagnet.
The above is the general principle of solenoid valve
In fact, according to the temperature and pressure of the flowing medium, for example, the pipeline has pressure and the self-flow state has no pressure. The working principle of solenoid valve is different.
For example, the zero-voltage startup is required under the gravity state, that is, the coil will suck up the whole brake body after being powered on.
The solenoid valve with pressure is a pin inserted on the brake body after the coil is energized, and the brake body is jacked up with the pressure of the fluid itself.
The difference between the two methods is that the solenoid valve in the self-flow state has a large volume because the coil needs to suck up the whole gate body
The solenoid valve under pressure only needs to suck up the pin, so its volume can be relatively small.
Direct acting solenoid valve:
Principle: When energized, the solenoid coil generates electromagnetic force to lift the closing part from the valve seat, and the valve opens; When the power is cut off, the electromagnetic force disappears, the spring presses the closing part on the valve seat, and the valve closes.
Features: It can work normally under vacuum, negative pressure and zero pressure, but the diameter generally does not exceed 25mm.
Distributed direct-acting solenoid valve:
Principle: It is a combination of direct-action and pilot type. When there is no pressure difference between the inlet and outlet, the electromagnetic force will directly lift the pilot small valve and the main valve closing part upward after energizing, and the valve will open. When the inlet and outlet reach the starting pressure difference, the electromagnetic force will pilot the small valve, the pressure in the lower chamber of the main valve will rise, and the pressure in the upper chamber will drop, so as to push the main valve upward by using the pressure difference; When the power is cut off, the pilot valve uses spring force or medium pressure to push the closing part and move downward to close the valve.
Features: It can also operate at zero differential pressure, vacuum and high pressure, but the power is large, so it must be installed horizontally.
Pilot operated solenoid valve:
Principle: when energized, the electromagnetic force opens the pilot hole, and the pressure in the upper chamber drops rapidly, forming a high and low pressure difference around the closing part. The fluid pressure pushes the closing part upward, and the valve opens; When the power is cut off, the spring force closes the pilot hole, and the inlet pressure rapidly forms a pressure difference of lower and higher around the valve closing parts through the bypass hole. The fluid pressure pushes the valve closing parts downward to close the valve.
Features: The upper limit of the fluid pressure range is high, and can be installed arbitrarily (customized), but the fluid pressure differential condition must be met.
The two-position two-way solenoid valve is composed of valve body and solenoid coil. It is a direct-acting structure with its own bridge rectifier circuit and overvoltage and overcurrent safety protection
The solenoid coil is not energized. At this time, the iron core of the solenoid valve leans against the double pipe end under the action of the return spring, closes the double pipe end outlet, and the single pipe end outlet is in the open state. The refrigerant flows from the single pipe end outlet pipe of the solenoid valve to the refrigerator evaporator, and the refrigerator evaporator flows back to the compressor to realize the refrigeration cycle.
The solenoid coil is energized. At this time, the iron core of the solenoid valve overcomes the force of the return spring and moves to the single pipe end under the action of the electromagnetic force, closes the single pipe end outlet, and the double pipe end outlet is in the open state. The refrigerant flows from the double pipe end outlet pipe of the solenoid valve to the refrigerator evaporator and returns to the compressor to realize the refrigeration cycle.
The two-position three-way solenoid valve is composed of valve body and solenoid coil. It is a direct-acting structure with bridge rectifier circuit and overvoltage and overcurrent safety protection А? Br>Working state 1 in the system: the solenoid valve coil is not energized. At this time, the iron core of the solenoid valve leans against the double pipe end under the action of the return spring, closes the double pipe end outlet, and the single pipe end outlet is in the open state. The refrigerant flows from the single pipe end outlet pipe of the solenoid valve to the refrigerator evaporator, and the refrigerator evaporator flows back to the compressor to realize the refrigeration cycle. (See Figure 1)
Working state 2 in the system: solenoid valve coil is energized. At this time, the iron core of the solenoid valve overcomes the force of the return spring and moves to the single pipe end under the action of the electromagnetic force, closes the single pipe end outlet, and the double pipe end outlet is in the open state. The refrigerant flows from the double pipe end outlet pipe of the solenoid valve to the refrigerator evaporator and returns to the compressor to realize the refrigeration cycle.