Common noise faults of the hottest hydraulic parts

2022-08-24
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Several common noise faults of hydraulic parts

taking the hydraulic elastic modulus and maximum experimental force of wlyl00 hydraulic excavator as an example, this paper introduces the possible causes of noise and troubleshooting methods as follows

1. Noise of piston pump or motor

(1) suction phenomenon is one of the main reasons for high noise of hydraulic pump. When air is mixed into the oil, cavitation is easy to form in its high-pressure area and propagate in the form of pressure wave, causing oil oscillation and cavitation noise in the system. The main reasons are:

① the oil filter and oil inlet pipe of the hydraulic pump are blocked or the oil viscosity is too high, which can cause the vacuum at the oil inlet of the pump to be too high and make the air penetrate

② the oil seal at the shaft end of the hydraulic pump and pilot pump is damaged, or the seal of the oil inlet pipe is poor, causing air to enter o

② the oil level in the oil tank is too low, which makes the oil inlet pipe of the hydraulic pump empty directly

when there is high noise in the operation of the hydraulic pump, the above parts should be checked first, and the problems found should be handled in time

(2) the internal components of the hydraulic pump are excessively worn, such as the wear and strain of the human-oriented mating parts of the constant lubrication instruments such as the cylinder body and port plate of the plunger pump, the plunger and the plunger hole, which will cause serious leakage in the hydraulic pump. When the hydraulic pump outputs high-pressure and small flow oil, it will produce flow pulsation and cause high noise. At this time, the deflection angle of the variable mechanism of the pilot system can be appropriately increased to improve the influence of internal leakage on the pump output flow. The servo valve spool of the hydraulic pump and the piston controlling the flow will also be worn and strained locally, Ivo lansbergen, President of Asia Pacific region of DSM engineering plastics business department, said: "the Xiaomi project reflects the pulsation of DSM in actively expanding China's domestic and overseas markets, causing fluctuations in the output flow and pressure of the hydraulic pump, resulting in greater vibration and noise at the pump outlet. At this time, components with serious wear and tear can be brush plated, matched or replaced.

(3) The valve plate of hydraulic pump is also one of the important components that are easy to cause noise. During the use of the valve plate, the surface wear or oil sludge deposition at the opening of the unloading groove will shorten the unloading groove and change the unloading position, resulting in oil trapping, which will then cause higher noise. In the normal repair process, the valve plate repaired by flat grinding will also have the consequence of shortening the unloading groove. At this time, if it is not properly trimmed in time, it will also produce large noise. During the assembly process, the large unloading groove of the port plate must be installed in the high-pressure chamber of the pump, and its sharp angle direction must be opposite to the rotation direction of the cylinder block, otherwise it will also bring greater noise to the system

2。 The noise of the overflow valve

the overflow valve is easy to produce high-frequency noise, which is mainly caused by the unstable performance of the pilot valve, that is, the noise caused by the air vibration caused by the high-frequency oscillation of the pressure in the front chamber of the pilot valve. The main reasons are:

(1) air is mixed in the oil, which forms cavitation in the front chamber of the pilot valve and causes high-frequency noise. At this time, the air shall be exhausted in time and the outside air shall be prevented from re entering

(2) the needle valve is excessively worn due to frequent opening during use, so that the conical surface of the needle valve and the valve seat cannot be tightly closed, resulting in unstable pilot flow, pressure fluctuations and noise. At this time, it should be repaired or replaced in time

(3) the pressure regulating function of the pilot valve is not stable under internal and external problems due to the fatigue deformation of the spring, resulting in large pressure fluctuations and noise. At this time, the spring should be replaced

3. Noise of hydraulic cylinder

(1) there is air mixed in the oil or the air in the hydraulic cylinder is not completely exhausted, causing cavitation under the action of high pressure and causing large noise. At this time, the air must be exhausted in time

(2) the cylinder head oil seal is too tight or the piston rod is bent, which will also produce noise due to other forces during movement. At this time, replace the oil seal or straighten the piston rod in time

4. pipeline noise

excessive dead bending of the pipeline or loose fixing clips can also produce vibration and noise. Therefore, dead bends should be avoided in the pipeline layout, and the loose clips should be tightened in time

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