How to deal with the fault of electric high pressure oil pump?

In our daily life, the application of electric pressure test pump is very wide, many enterprises will use this machine, its role can not be ignored, to bring great convenience to people. However, the pressure regulation of small hot oil pump in daily use will be abnormal, the main valve core will be stuck, and the oil return flow of overflow valve will fluctuate.

For example, the main valve core of the overflow valve of the electric fuel pump is stuck:

Fault analysis:

In the pressure control circuit, the hydraulic pump is a constant displacement pump, and the power of the three position four-way reversing valve of the small oil well pump is y. Therefore, the hydraulic cylinder stops working, the system does not unload, and all the pressure oil from the hydraulic pump overflows back to the oil tank through the relief valve. The relief valve of the system generally adopts the pilot type lubricating valve, which has a three-stage concentric structure. This kind of relief valve is suitable for high pressure and large flow system, with high coaxiality requirements and good pressure regulating and overflow performance.

In the system, when the directional valve is in the middle position, adjust the pressure of the relief valve, and it is found that the relief valve works normally when the pressure value is lower than 10MPa; when the pressure is adjusted to any pressure value higher than iompa, the system will emit a scream. At this time, we can see that the pointer of the pressure gauge vibrates violently, and the noise comes from the relief valve.

Exclusion method:

This is because in the three-stage coaxial high-pressure relief valve, there are two sliding fits between the main valve core, the valve body and the valve cover. After the assembly of the valve body and the valve cover, if the coaxiality deviation of the inner hole exceeds the specified requirements, the main valve core will not be able to move flexibly, and can only stick to one side of the inner hole for abnormal movement. Adjusting to a certain pressure will inevitably cause the vibration of the main valve core. The vibration is not the normal vibration of the main valve core in the process of operation, but the high frequency vibration caused by the main valve core stuck in a certain position (at this time, the main valve core bears the hydraulic clamping force at the same time). This high frequency vibration will inevitably cause strong vibration of the spring, especially the pressure regulating spring of the pilot valve of the poppet valve, and produce abnormal noise.