What is the circuit of a hydraulic system?
Simply put, it is a circuit that is composed of certain hydraulic components and accessories and can complete a certain function. The hydraulic system circuits are classified into pressure holding circuits, unloading circuits, reversing circuits, locking circuits, etc.
Principle of hydraulic system reversing circuit:
It is suitable for realizing the oil circuit that changes the movement direction of the actuator. A simple reversing circuit can be realized by using various reversing valves or changing the oil delivery direction of a two-way variable hydraulic pump. The reversing valve includes solenoid valve, electro-hydraulic valve and manual valve. It is divided into two driving forms: DC and AC. It is characterized by fast commutation action and certain impact force. However, the AC solenoid valve should not be switched frequently.
Principle of hydraulic system unloading circuit:
- The role of unloading: It can make the system without pressure without stopping the motor and pump, because if the motor and pump stop in a short time during loading and unloading, they will have to stop frequently, which is harmful to the motor and pump. Without unloading, it runs under load and consumes more power.
- Unloading principle: Generally, unloading valve is used for unloading; the unloading valve is installed on the branch road of the pump outlet, which can be manual or electric. When it is turned on, the pump oil is directly returned to the oil pool. It can also be partially unloaded, as long as the unloading valve is installed on the pressure pipe branch of the local oil circuit.
Principle of hydraulic system locking circuit:
The first type is a circuit locked with a reversing valve. Due to the influence of leakage in the reversing valve, the reversing valve is used for locking, and the locking accuracy is low.
The second type is a loop locked with a one-way valve. When the hydraulic pump stops working, the movement of the piston of the hydraulic cylinder in the right direction is locked by the one-way valve, and it can move in the left direction. Only when the piston moves to the left to the extreme position, can the two-way locking be achieved. The locking accuracy of this circuit is also affected by the leakage in the reversing valve.
The third type is a loop locked with a hydraulically controlled check valve. When the reversing valve is in the neutral position, the hydraulic control check valve is allowed to enter the oil and the control oil port is communicated with the oil tank, the hydraulic control check valve is quickly closed, and the leftward movement of the hydraulic cylinder piston is locked by the hydraulic control check valve. It can move to the right and can only be locked in one direction.
The fourth type is the double hydraulic control check valve (hydraulic lock) to lock the circuit. Such locking circuits are commonly used in hydraulic systems of construction machinery. When the three-position four-way electromagnetic reversing valve is in the neutral position, the oil inlet and control ports of the two hydraulic control check valves are in communication with the oil tank, so that the two hydraulic control check valves are quickly closed, which can realize the two-way hydraulic cylinder Lock tight.
Further reading:Analysis and Treatment of Common Faults in Hydraulic System