Fault phenomenon, reason analysis and improvement method of hydraulic oil pump

Fault phenomenon, reason analysis and improvement method of hydraulic oil pump

I. Analysis of the failure phenomenon and cause of hydraulic oil pump

1. Check the inside leakage of the boom cylinder. The easiest way is to raise the boom to see if there is a clear and free fall. If the drop is obvious, remove the cylinder and check that the seal ring has been worn out and should be replaced;

2. Check the valve. First, clean the safety valve and check if the spool is worn out. Replace it if worn. After the safety valve is installed, if there is still no change, check the condition of the valve plug wear. The clearance limit is 0.06mm, and the wear should be replaced.

3. Measure the pressure of the hydraulic pump. If the pressure is low, then adjust, and the pressure can not be adjusted, then the hydraulic pump is seriously worn.

In general, the main reason that can cause hydraulic oil pump boom loading to fail is:

a. The hydraulic pump is heavily worn. When the pump is running at low speed, the leakage in the pump is serious. At high speed, the pump pressure slightly increases. However, due to the wear and internal leakage of the pump, the volumetric efficiency drops significantly and it is difficult to reach the rated pressure. The long time working of the hydraulic pump exacerbates the wear and increases the oil temperature. As a result, the hydraulic components are worn out, and the seals are aged and damaged. The seal capacity is lost, and the hydraulic oil deteriorates, eventually leading to failure.

b. The selection of hydraulic components is unreasonable. The boom cylinder specifications are 70/40 non-standard series, and the seals are also non-standard parts. The manufacturing cost is high and the seal replacement is inconvenient. The cylinder bore of the boom cylinder is bound to make the system set high pressure;

c. The design of the hydraulic oil pump system is unreasonable. As can be seen from Figure 1, the control valve and the hydraulic steering gear is a single pump in series, the safety valve set pressure is 16MPa, and the rated working pressure of the hydraulic pump is also 16MPa. Hydraulic pumps are often operated under full load or long-term overload (high pressure) conditions, and the system has hydraulic impact, long-term oil change, hydraulic oil contamination, exacerbated hydraulic pump wear, resulting in hydraulic pump casing burst (later discovered Such failures).

Second, the hydraulic pump improvement and effect

1. Improve hydraulic system design. After many arguments, the advanced priority valve and the load-sensing full-hydraulic steering gear were used. The new system was able to prioritize the distribution of flow according to the steering requirements. The amount of the load and the steering wheel rotation speed ensured that the fuel supply was adequate. All can be used to supply the working device circuit, thus eliminating the power loss caused by excessive oil supply to the steering circuit, improving the system efficiency and reducing the working pressure of the hydraulic pump;

2. Optimize the design of the boom cylinder and hydraulic pump to reduce the system working pressure. With optimized calculations, the boom cylinder uses the standard series 80/4. The displacement of the hydraulic oil pump was increased from 10 ml/r to 14 ml/r, and the system set pressure was 14 MPa, which satisfied the lifting force and speed requirements of the boom cylinder.

3. During use, attention should also be paid to the correct use and maintenance of the hydraulic pump of the loader. Add or replace the hydraulic oil regularly to maintain the cleanliness of the hydraulic oil and strengthen daily inspection and maintenance.

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