What is the difference in principle between a proportional solenoid valve and an electric proportional valve?（3）

Third, the classification of the two is different:

1. Classification of proportional valves: 

1) Electromagnetic proportional valve: Electromagnetic type refers to a proportional electromagnet as an electromechanical conversion element, which converts the input current signal into a mechanical signal of force and displacement, and then outputs parameters such as control pressure, flow, and direction. proportional valve. 

2) Electric proportional valve: The electric type refers to a proportional valve that uses a DC servo motor as an electromechanical conversion element. The DC servo motor converts the input electrical signal into a rotational speed, and then outputs force and displacement through a reduction device and a conversion mechanism such as a lead screw nut, a rack or a gear cam, and further controls hydraulic parameters. 

3) Electro-hydraulic proportional valve: Electro-hydraulic refers to the proportional valve with torque motor and nozzle baffle structure as the pilot control stage. Input different electrical signals to the torque motor, and output displacement or angular displacement through the baffle connected to it (sometimes the armature of the torque motor is the baffle), thereby changing the distance between the baffle and the nozzle, and changing the flow of oil ejected from the nozzle resistance, and then control the transmission parameters.

2. Classification of common valves: 

1) Classification by control mode: manual, electric control, hydraulic control. 

2) Classification by function: flow valve (throttle valve, speed control valve, diversion and flow collection valve), pressure valve (overflow valve, pressure reducing valve, sequence valve, unloading valve), directional valve (electromagnetic reversing valve, Manual reversing valve, one-way valve, hydraulic control one-way valve). 

3) According to the installation method: flat valve, pipe valve, stack valve, screw cartridge valve, cover valve. 

4) Divided into manual valves, electric valves, electric valves, hydraulic valves, electro-hydraulic valves, etc.