The concept of hydraulic valve (3)

Pressure control:

According to the purpose, it is divided into overflow valve, pressure reducing valve and sequence valve.

(1)Relief valve: It can control the hydraulic system to maintain a constant state when it reaches the set pressure. The overflow valve used for overload protection is called safety valve. When the system fails and the pressure rises to the limit value that may cause damage, the valve port will open and overflow to ensure the safety of the system.

(2)Pressure reducing valve: It can control the branch circuit to obtain a stable pressure lower than the oil pressure of the main circuit. According to the different pressure functions it controls, the pressure reducing valve can be divided into fixed value pressure reducing valve (the output pressure is a constant value), fixed difference pressure reducing valve (the difference between input and output pressure is a fixed value) and fixed ratio pressure reducing valve (Keep a certain ratio between input and output pressure).

⑶Sequence valve: After one actuator (such as hydraulic cylinder, hydraulic motor, etc.) is activated, other actuators are activated in sequence. The pressure generated by the oil pump first pushes the hydraulic cylinder 1 to move, and at the same time acts on the area A through the oil inlet of the sequence valve. When the hydraulic cylinder 1 moves completely, the pressure rises, and the upward thrust acting on the area A is greater than the setting of the spring After the value is set, the spool rises to connect the oil inlet port with the oil outlet port, so that the hydraulic cylinder 2 moves.