We all know that the intake valve, as the "mouth and nose" of the air compression system, plays a very important role in the operation of the entire air compressor. The air filtered by the air filter enters the head through the intake valve and completes the compression process in the head. Today we compare the intake valves on industrial frequency and variable frequency air compressors.
First of all, for industrial frequency air compressors, during the normal operation of the air compressor, the intake valve plays the role of starting, loading, air intake adjustment, unloading and shutdown.
Startup: When the air compressor is started, the intake valve is closed, which reduces the motor load at startup. Only the small holes on the valve are used to intake air, so that the air compressor forms internal pressure and completes the self-lubrication of each component.
Loading: After the motor star-delta start conversion is completed, the main control system will compare the set pressure with the actual system pressure. When the actual pressure is lower than the system set pressure, the intake valve opens and the air compressor is loaded.
Intake volume adjustment: Generally, a capacity regulating valve (inverse proportional valve) is connected in parallel to the solenoid valve bypass. The function of this regulating valve is to reduce the number of unloading times of the air compressor and the number of start-stop times of the motor by slightly adjusting the intake volume. It belongs to stepless adjustment. This kind of adjustment has a certain pressure range.
Unloading: When the pressure of the air compressor is higher than the upper pressure limit set by the system, the intake valve plate will be closed, and air will only be taken in through the small hole on the intake valve. At the same time, the vent valve is opened so that the gas of the air compressor only maintains the internal pressure.
Shutdown: After the motor stops, the check valve on the intake valve closes quickly to prevent the lubricating oil in the machine head from spraying out. At the same time, the vent valve continues to vent, so that the internal pressure of the air compressor reaches the atmospheric pressure to ensure normal start next time.
Secondly, compared with the intake valve of the power frequency air compressor, the variable frequency air compressor relies on its own speed change to change the intake volume, and its matching intake valve structure is relatively simple.
When the variable frequency air compressor is equipped with an intake valve, the negative pressure formed inside the head offsets the force of the balance block connected to the valve, ensuring that the intake volume can be adjusted according to the motor speed. On the other hand, it can ensure that the oil in the head does not spray out when the machine is shut down, and play a role in emptying.