Created on:2021-05-26 16:06

Failure and troubleshooting of PV2R vane pump

Failure and troubleshooting of PV2R vane pump

① PV2R type high pressure and low noise vane pump is a kind of hydraulic pump product introduced from Japan oil research company in 1980s. Its structure is basically similar to YB1 series vane pump in China. It consists of stator, rotor, blade and port plate. The stator transition curve is of high order, so the noise of the pump is low. The blade is a single blade. The working pressure of the pump (the rated pressure of the pump is 16MPa) is increased by thinning the thickness (the minimum thickness of the blade is 1.6mm) and improving the strength of the stator. The pump is used as the oil source of a special hydraulic press (6 sets of the same equipment).

After using the pump for 3 months, it was found that the blade of a hydraulic press was broken at the same time.

② According to the working principle of vane pump, when the pump is working, the vane rotates with the rotor. In the transition area (pressure oil area), the up and down pressure before and after the vane is the same, and the radial expansion resistance of the vane is small. However, in the working area (sealing area), the situation is different. At this time, the blade plays a role of sealing the high and low pressure oil chamber. There is a pressure difference between the front and back of the blade, and there is a tilt phenomenon in the blade groove (Fig. E). In this way, at two points a and B, the blade contacts with the rotor and produces a d-clamping force. With the increase of the working pressure of the pump, the pressure difference area increases and the clamping force also increases. At this time, if the blade does not enter the transition zone, the blade will not move radially and will not break; once it enters the transition zone, the blade needs to move radially. Because the blade of the pump is thin, if there are internal hidden dangers in the original production process of the pump (such as blade machining, heat treatment, material performance failing to meet the design requirements) and the system oil pollution is out of tolerance, the blade will be stuck The blade is broken because of the tightness.

E1.jpg

Another reason is that when the blade just enters the oil pressure area, the blade is pushed into the rotor groove by the inner surface of the stator to make radial movement, but because the triangular groove at the end of the annular hole of the valve plate is not connected with the sealing cavity, the blade is in the unilateral stress state, and the force on the upper and lower parts of the blade is unbalanced, only under the root hydraulic pressure; at the same time, the width gap between the blade, rotor and stator is 15-30 μ M When the contamination in the oil is greater than the clearance, the blade is easy to be clamped and broken.

③ Prevention measures and effects in order to prevent the blade from breaking, on the one hand, the advanced transition curve should be adopted to make the blade move smoothly without impact; at the same time, when the blade enters the oil pressure area, the triangular groove at the end of the annular hole in the oil pressure area of the valve plate should be connected with the sealing chamber; on the other hand, the operator should regularly check the inlet and outlet filter devices of the hydraulic system and the air filter with oil filling filter every month Filter. The medium used in the pump is No.46 ordinary hydraulic oil, and its quality index should meet the relevant regulations. The cleanliness of the oil medium should always be maintained in the use of the pump, and its cleanliness is within 12 level of nas1638.

When the oil cleanliness is up to the standard, PV2R pump works normally.

(3) Trouble shooting of 63pcy14-1 swash plate constant pressure variable axial piston pump

① The hydraulic system of a new equipment uses 63pcy14-1 swash plate constant pressure variable axial piston pump made in China. After the equipment arrives, the fire-resistant hydraulic oil is selected according to the wiggs series hydraulic pump, and the oil is added into the system with oil filling truck as required. 15 minutes after the whole machine started, there was a "bang bang" noise from the pump to the inlet of the integrated oil circuit block, and the pipeline was accompanied by vibration. Listen with a long handle screwdriver, there was a crisp metal knocking sound at the inlet and outlet of the integrated oil circuit block, there was a weak vibration and noise at the variable head of the pump, and the system pressure could only rise to 5 If the relief valve is adjusted continuously, the pressure is difficult to increase, and the noise increases sharply, but there is no noise at the fixing bolt of the pipeline. The pump case is hot by hand.

② Cause analysis: after eliminating the overflow valve fault in the hydraulic system and confirming the hydraulic pump fault, it was decided to dismantle the Zhuzhai pump. After disassembly, it was found that three plungers had been pulled off from the slippers, two of which were cracked, and one slipper had been broken. At the same time, it was found that the matching surface of the plunger and cylinder liner was scratched. Therefore, the oil return filter was removed immediately, and it was found that there were a lot of metal chips on the filter element and the hydraulic oil was seriously polluted in just over an hour from the failure of the system to the confirmation of the damage of the hydraulic pump. The reason is that the equipment manufacturer did not thoroughly clean the oil tank and other hydraulic components, and there was a design error, so the leakage port of the plunger pump was designed in the oil tank close to the oil inlet pipe of the pump.

③ Troubleshooting method and effect: after the initial troubleshooting, filter the hydraulic oil, clean the system, and replace it with a new plunger pump, but the fault still exists. Finally, it is found that the viscosity of hs620 fireproof oil is 43mm2gs, which is in the lowest limit of 414-74.8mm2/s required by PCY series piston pump manufacturer. On the other hand, due to the high temperature on site and the poor lubricity of hs620 oil, the hydrostatic bearing effect between slipper and swash plate is poor for domestic pumps. The slipper can not float and form oil film, resulting in the damage of plunger pump in a very short time. Therefore, it is considered that the selection of hydraulic oil is improper. After replacing the hydraulic pump, use the anti-wear hydraulic oil. The equipment will run normally.

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