1. Butterfly inlet control valve: when the screw air compressor is started, the inlet valve disc is closed to ensure no load start. When the motor operates under heavy load, the three-phase solenoid valve is opened after being powered on. The servo cylinder of the incoming gas inlet valve pushes the valve rod of the servo cylinder to drive the inlet butterfly valve to fully open and start heavy load operation. The single swing check valve inside the butterfly air inlet control valve is equipped with counterweight and fluororubber sealing ring. When starting up, the main engine of the screw air compressor sucks air. Due to the pressure difference, the check valve can be closed tightly and quickly in time to ensure that there is no phenomenon of oil spitting during shutdown. The opening and closing of the butterfly valve is controlled by the cylinder manually. According to the received pressure signal and combined with the anti proportional valve, the length of the piston rod of the cylinder can be controlled. The butterfly valve can be opened or closed, so as to adjust the air intake of the screw air compressor.

The structure of butterfly intake control valve is composed of valve body, single swing check valve, butterfly valve and servo cylinder.

2. Air inlet valve: use the up and down action of the piston in the air inlet valve of the air compressor to control the operation of the empty and loaded vehicle of the air compressor. When the air compressor is started, stopped and unloaded, the relief solenoid valve uses the air inlet to supply air to the piston to close the piston upward; When the air compressor works at full load, the discharge solenoid valve is powered on to stop the discharge, the piston chamber is discharged from the exhaust port, the intake valve piston decreases due to the intake pressure difference, the intake valve is fully opened, and the air compressor works at full load; When the pressure reaches the upper limit of the set pressure, the discharge solenoid valve loses power and begins to discharge, and push the intake valve piston up to make the intake valve closed. At this time, the air compressor is in idle-load state.

The structure of piston intake valve is composed of air inlet, valve upper cover, piston, base and discharge solenoid valve.