Hot knowledge: principle and classification analysis of proportional valves

The proportional control valve is mainly used for open loop control; the output of the proportional control valve is proportional to the input signal, and the magnetic force generated by the solenoid in the proportional control valve is proportional to the current.

　　In the traditional type of hydraulic control valve, only the hydraulic pressure can be controlled at a fixed value. For example, the pressure valve operates at a certain set pressure, the flow valve maintains the set flow rate, and the directional valve controls the hydraulic pressure. Switching the flow direction on/off. Therefore, the system functions composed of these control valves are subject to some restrictions. With the advancement of technology, many hydraulic systems require that the flow and pressure can be continuously or proportionally changed with the change of the control valve input signal. Although the hydraulic servo system can meet its requirements and has high accuracy, for most industries, they do not require the system to have such a high quality. They hope to ensure a certain control performance and at the same time low price. Reliable work and simple maintenance, so the proportional control valve was developed under this background.

　　Proportional control valves can be divided into three types: pressure control valves, flow control and directional control valves.

　　 Pressure control valve: The manual adjustment device that replaces the pilot relief valve with a proportional solenoid valve becomes a pilot proportional relief valve, and the output hydraulic pressure is continuously or proportionally controlled by the input signal.

　　Flow control valve: A proportional solenoid valve is used to replace the manual adjustment device of the throttle valve or speed control valve, and the throttle opening of the throttle valve or speed control valve is controlled by the input signal, which can be controlled continuously or proportionally Output flow. Therefore, the opening of the throttle can be determined by the voltage of the input signal.

　　 Directional control valve: The proportional solenoid valve replaces the general solenoid valve of the directional valve to form a direct-acting proportional directional valve. Not only can the sliding shaft be transposed, but the transposition stroke can be continuously or proportionally changed, thus connecting the oil port The oil passage area can also be changed continuously or proportionally, so the proportional directional control valve can not only control the movement direction of the actuator, but also control its speed.

　　 The hydraulic components actuated by the various proportional valves above are hydraulic cylinders or hydraulic motors.