Typical fault diagnosis and troubleshooting method of Manifold Block leading relief valve
Pilot relief valve has a variety of structures, pilot relief valve is a typical three-section concentric structure of the pilot relief valve, it is composed of the pilot valve and the main valve two parts. The pilot type relief valve has the advantages of large pressure range, small pressure regulation deviation, small pressure oscillation, sensitive action, large overload capacity and small noise.
With the development of hydraulic system of construction machinery towards medium, high pressure and super high pressure, the pilot relief valve is widely used in the control oil circuit of hydraulic system of construction machinery. In practice, in order to give full play to its efficiency and protect the control system, accurate and timely diagnosis and elimination of the failure of the pilot relief valve is a key link.
1, control failure, so that the main engine does not move
The failure of the pilot relief valve will cause the main engine to fail. According to the phenomenon, the reasons are analyzed as follows: the pilot valve spool spring breaks; Yin ni hole blockage; The pilot valve port is not well sealed; Main spool stuck, etc. The corresponding elimination measures are: replace or add flat pad in the broken place for emergency use; Cleaning dredge; Grind or break the oil circuit for emergency use; Grinding, cleaning.
2. The pressure limit is unstable
The pressure limit of the pilot relief valve is unstable, which is manifested by the low or high pressure of the hydraulic system, the weak action of the hydraulic actuator or the burst of the oil pipe, pump body and valve body.
The reasons for this failure are as follows: improper pressure adjustment; Pilot valve spool spring bending or softening; The oil is too dirty or the oil flow is not smooth. The corresponding elimination measures are: readjusting; Calibration, padding or replacement; Replace and clean.
Pilot type relief valve sealing performance
The sealing performance of the pilot relief valve refers to the ability of the pilot relief valve seal parts to prevent media leakage, which is the most important technical performance index of the pilot relief valve.
There are three sealing parts of the pilot relief valve: the contact between the opening and closing parts and the sealing surface of the seat; Packing and valve stem and packing box matching place; Body to bonnet connection.
One of the former leakage is called internal leakage, which is commonly known as lax, and it will affect the ability of the pilot relief valve to cut off the medium. For block valves, internal leakage is not allowed. The latter two leaks are called external leakage, that is, the medium leaks from the valve to the valve outside. Leakage will cause material loss, pollution of the environment, and even cause accidents when serious. For flammable and explosive, toxic or radioactive media, leakage is not allowed, so the pilot relief valve must have reliable sealing performance.