What is a Hydraulic Valve?

Introduction of Hydraulic Valve

Hydraulic valve is a kind of automatic hydraulic parts operated with pressure oil, it is controlled by pressure valve pressure oil, usually combined with electromagnetic pressure valve, can be used for remote control of hydropower station oil, gas, water pipe system. Often used for clamping, control, lubrication and other oil circuit. There are direct action type and lead type, the use of lead type.

A component in hydraulic transmission used to control the pressure, flow, and direction of liquids. The control pressure is called pressure control valve, the control flow is called flow control valve, and the control on, off and flow direction is called direction control valve.

Classification

According to the control method classification: manual, electronic control, hydraulic control.

Classification by function: flow valve (throttle valve, speed regulating valve, shunt collecting valve), pressure valve (relief valve, pressure reducing valve, sequence valve, unloading valve), direction valve (electromagnetic reversing valve, manual reversing valve, check valve, hydraulic control check valve).

According to the installation mode: plate valve, tubular valve, stack valve, threaded cartridge valve, cover valve.

According to the control mode: manual valve, power valve, electric valve, hydraulic valve, electro-hydraulic valve and so on.

Direction Control

It is divided into check valve and reversing valve according to its use. Check valve: only allow the fluid in the pipeline one-way through, reverse is cut off. Reversing valve: change the on - off relationship between different pipelines. According to the valve core in the valve body working position number of two, three, etc.; According to the number of controlled channels divided into two, three, four, five, etc.; According to the spool drive mode of breaking, motor, electric, hydraulic, etc. In the late 1960s, the electro-hydraulic proportional control valve was developed on the basis of the above mentioned hydraulic control valves. Its output (pressure, flow) can change continuously with the input electrical signal. Electro-hydraulic proportional control valves are divided into electro-hydraulic proportional pressure control valves, electro-hydraulic proportional flow control valves and electro-hydraulic proportional direction control valves according to different functions.

Pressure Control

According to the use of relief valve, pressure reducing valve and sequence valve.

1. Relief valve: can control the hydraulic system to maintain a constant state when reaching the setting pressure. Relief valves for overload protection are called safety valves. When the system fails and the pressure rises to the limit value that may cause damage, the valve port will be opened and overflow to ensure the safety of the system.
2. Pressure reducing valve: can control the branch circuit to obtain stable pressure lower than the main circuit oil pressure. Reducing valve according to the pressure function it controls is different, and can be divided into fixed value reducing valve (output pressure for constant value), fixed difference reducing valve (input and output pressure difference for fixed value) and fixed ratio reducing valve (input and output pressure to maintain a certain proportion).
3. Sequence valve: can make an executive component (such as hydraulic cylinder, hydraulic motor, etc.) action, and then in order to make other executive components action.

Flow Control

The throttle area between the regulating valve core and the valve body and the local resistance generated by it to adjust the flow, so as to control the speed of the actuator. Flow control valves are divided into 5 types according to their uses.

1. Throttle valve: after adjusting the throttle port area, can make the load pressure changes little and the movement uniformity requirements are not high, the speed of the actuator is basically stable.
2. Speed regulating valve: when the load pressure changes, the inlet and outlet pressure difference of the throttle valve can be maintained as a fixed value. In this way, after the orifice area is set, no matter how the load pressure changes, the speed regulating valve can keep the flow through the throttle valve unchanged, so that the motion speed of the actuator is stable.
3. Shunt valve: regardless of the size of the load, can make the same oil source of two executive components to get the same flow for the same amount of shunt valve or synchronous valve; A proportional diverter valve is obtained which distributes the flow proportionally.
4. Collecting valve: the function is opposite to the shunt valve, so that the flow into the collecting valve is distributed proportionally.
5. Shunt valve: Both shunt valve and flow valve two functions.