The input signal increases, the air supply solenoid valve pilot valve1 reverses, and the exhaust solenoid pilot valve 7 is in the reset state, the air supply pressure enters the pilot chamber 5 from the SUP port through valve 1, the pilot chamber pressure rises, the air pressure acts above the diaphragm 2, the air supply valve spool 4 connected with the diaphragm 2 is opened, the exhaust valve spool 3 is closed, and the output pressure is generated. This output pressure is fed back to control loop 8 through pressure sensor 6. Here, a quick comparison is made with the target value until the output pressure is proportional to the input signal, resulting in a change in the output pressure proportional to the change in the input signal. Because there is no nozzle baffle mechanism, the valve is not sensitive to impurities and has high reliability.

Characteristic
1) It can realize the stepless adjustment of pressure and speed and avoid the impact phenomenon when the normal switching valve reverses.
2) Can realize remote control and program control.
3) Compared with intermittent control, the system is simplified and the components are greatly reduced.
4) Compared with the hydraulic proportional valve, small volume, light weight, simple structure, low cost, but the response speed is much slower than the hydraulic system, and more sensitive to load changes.
5) The use of small power, less heat, low noise.
6) There will be no fire and no environmental pollution. The effect of temperature change is small.