Created on:2021-12-07 13:32

Repair of vane pump

Repair of vane pump

1. Repair of oil distribution plate and side plate

The oil distribution plate and side plate are mostly worn and strained. For Yb vane pump, as long as the total depth of wear and strain between the oil distribution plate and the side plate is not greater than 0.8mm, there is 1mm assembly clearance between the left and right pump bodies, so the scars can be removed by flat grinding, and then assembled after polishing. The upper and lower notches B on the oil distribution plate are oil suction windows, the two waist holes a are oil pressure windows, and the separated part is oil sealing area, as shown in Figure J. A triangular groove is opened at the end of the waist hole, which is used to gradually connect the sealing volume of the blade with the high-pressure chamber to avoid hydraulic impact and reduce vibration and noise. Note that after grinding, the size of the unloading triangular groove will be greatly shortened. If it is not slender, vibration and noise will be generated, but it can not be repaired too long. Because it is too long, the oil suction chamber may be connected with the oil pressure chamber, Reduce the output flow of the pump. An annular groove C is opened on the oil distribution plate corresponding to the blade root, and two small holes D in the annular groove are connected with the oil drain hole, which leads pressure oil to act on the bottom of the blade. During grinding, pay attention to maintain the depth and shape of the annular groove C, and do not damage or block the two small holes D, otherwise the vane pump cannot work normally. The f hole on the oil distribution plate is an oil drain hole, which leads the oil leakage between the pump bodies to the oil suction chamber. Pay attention not to block the f hole during grinding. The parallelism of the contact plane between the repaired side plate or oil distribution plate and the rotor shall be within 0.01mm, the perpendicularity between the end face and the inner hole (oil distribution plate) shall be within 0.01mm, the surface roughness of the end face shall meet the technical requirements, and the flatness shall be 0.05mm.

2. Repair of stator

When the vane pump works, the vane is close to the curved surface of the stator under the action of pressure oil and centrifugal force. The contact pressure between the vane and the curved surface of the stator is large, which may cause wear. In the oil inlet chamber, there is high pressure oil at the blade root, so the oil inlet chamber is most vulnerable to wear. When the curve surface is less worn, it can be polished with metallographic sandpaper; If the wear is serious or the surface is serrated, it must be grinded and repaired on a special grinder; If there is no special grinder for repair, only new parts can be replaced. Another simple method is to turn the stator 180 ° for installation, and re process the positioning hole at the symmetrical position, as shown in Figure K. At this time, the original oil inlet chamber on the stator becomes an oil pressure chamber.

3. Repair of rotor

The end face of the rotor is in contact with the valve plate, which is prone to wear. If the wear is not serious, the roughened part can be polished with an oilstone or polished by grinding. If there is much wear, the end face shall be polished by positioning the mandrel on the cylindrical grinder. The parallelism of both ends shall not be greater than 0.008mm and the surface roughness Ra ≤ 0.16 μ m. The perpendicularity between the end face and the hole shall not be greater than 0.01mm. It shall be noted that after grinding the rotor end face, the blade width ratio shall be grinded according to the rotor width, and it shall be ensured that the blade width is less than 0.005mm of the rotor width.

Due to the frequent reciprocating motion of the blade, the blade groove of the rotor has a large amount of wear, but the wear of each groove is not necessarily the same. In order to control the matching clearance between the blade and the blade groove is basically the same, the groove needs to be reground with a special grinder, and then the blade is equipped separately to ensure that the matching clearance is 0.013 ~ 0.018mm. If the blade does not move flexibly in the groove, it can be repaired by grinding.

4. Blade repair

The top of the blade in contact with the curved surface of the inner ring of the stator and the two sides in contact with the port plate are most vulnerable to wear. After wear, it needs to be repaired with a special fixture. Figure L shows the required accuracy of the blade, and dimension L is the rotor width.

As shown in Figure m, it is a fixture for grinding four surfaces of blades. During grinding, all blades in the vane pump are clamped in the fixture at one time and clamped in four times to grind two sides and two end faces of blades. Figure n shows the fixture for grinding blade chamfer. During grinding, the chamfer shall reach 1 × 45 °, which is basically 1 / 2 of the blade thickness. It is better to grind it into a circular arc shape. In this way, the blade can slide smoothly on the curved surface of the inner ring of the stator without affecting the oil delivery and generating noise. After grinding, deburring shall be carried out with oilstone. If the top of the blade is seriously worn, the damaged top can also be used as the root. If the two planes contacting the blade and the rotor slot are worn, they can be put on the surface grinder for grinding or grinding, but the matching clearance with the rotor slot shall be ensured to be 0.013 ~ 0.018mm, otherwise new blades shall be used for grinding or grinding.

MN1.jpg

5. Repair of support block and sliding block of variable displacement pump

The sliding block, support block, needle roller cage and rectangular chuck are assembled, which are the main components to bear the hydraulic pressure in the stator pressure oil chamber. The contact plane of the sliding block, support block and needle roller is easy to wear, and even be pressed out of the track dent or needle roller deformation. At this time, it can be ground (or flat ground) according to the requirements shown in Figure o, and equipped with roller needles of the same specification and size (diameter error < 0.005mm). Assembly is to adjust the height dimension of the rectangular snap ring so that the slider can move left and right for a sufficient distance. In the support direction of the support block, the eccentricity of the stator center relative to the rotor center is usually 0.04 ~ 0.08mm. For this purpose, a bright steel strip or flat copper sheet with appropriate thickness shall be padded between the support block and the cover (see Figure P). In order to ensure that the downward displacement eccentricity is 0.04 ~ 0.08mm, the thickness of bright steel strip shall be

δ= (1/2)(D-d)-(h1-h2)+(0.04~0.08)

OP1.jpg

6. Maintenance of variable displacement pump control piston

The spring piston and feedback piston move frequently, and the outer circle is easy to wear. The left and right sides of the spring piston are drained, and the sealing requirements are not strict. As long as the burrs and foreign matters between the outer circle and the pump body hole are removed to make it move flexibly. The outlet pressure oil of the pump is connected to one side of the feedback piston and sealed by clearance. The volumetric efficiency of the pump will be reduced after its outer circle is worn. It can be repaired or replaced by brush plating. The material is 40Cr, machined after quenching and tempering, and then hardened to hrc45. The clearance with the pump body hole shall be controlled at 0.008 ~ 0.015mm

7. Bearing repair

The rolling bearing cannot be reused after wear. Some vane pumps produced in recent years adopt PTFE plastic composite sliding bearings with steel sleeves, which have been produced by special manufacturers. The inner hole surface roughness Ra ≤ 0.4 μ m. The same cylindricity of inner and outer circles is 0.02mm, and the fit clearance with shaft diameter is 0.05 ~ 0.07mm. Suitable double row needle roller bearing or tin bronze sliding bearing can also be selected.

8. Shaft repair

Shaft fracture is generally rare, mainly due to the wear of the bearing. The journal can be ground until the scar is removed, but the sliding bearing shall be equipped by itself, with coaxiality of 0.02mm and inner hole surface roughness Ra ≤ 0.4 μ m. If the shaft is broken, it needs mapping and processing.

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