In the pneumatic control system, the ON-OFF valve with lower frequency is used to control the on-off of the gas path. By reducing the pressure valve to adjust the required pressure, by throttle valve to adjust the required flow. This kind of traditional pneumatic control system to have more than one output force and more than one speed, you need more than one pressure reducing valve, throttle valve and reversing valve. In this way, not only the components need more, the cost is high, the composition of the system is complex, and many components need to be adjusted manually in advance. The electrical proportional valve control belongs to continuous control, which is characterized by the output with the input (current value or voltage value) changes, there is a certain proportional relationship between the output and the input. Proportional control can be divided into open loop control and closed loop control. Closed-loop control of a signal feedback system.

Electro-hydraulic proportional valve is the proportional solenoid input voltage signal in the valve to produce corresponding action, so that the working valve spool displacement, valve port size changes and to complete the pressure and flow output components proportional to the input voltage. Spool displacement can also be fed back mechanically, hydraulically, or electrically. Electro-hydraulic proportional valve has a variety of forms, easy to use electrical and computer control of various electro-hydraulic systems, high control precision, flexible installation and use, and strong anti-pollution ability and other advantages, the application field is widening. Electric proportional valve fast and easy automatic selection and collection, R & D and production of cartridge proportional valve and proportional multiway valve fully take into account the characteristics of construction machinery, with pilot control, load sensing and pressure compensation functions. It is of great significance to improve the overall technical level of mobile hydraulic machinery. In particular, the electronic pilot operation, wireless remote control and wired remote control show good application prospects.