Identification and repair of wear characteristics

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Wear characteristics, identification and repair of plunger oil pump

1. Wear characteristics of plunger and coupling parts the wear of plunger coupling parts is mainly concentrated in the plunger head, the beam, the stop supply side and the oil inlet and return hole of the plunger

(1) the wear feature of the plunger head is that the wear is the largest here. There are groove marks on the contact surface, which are deep at the top and shallow at the bottom, thick at the top and fine at the bottom. The wear part is milky white, especially under light. The maximum depth of the groove mark can reach 0..025 mm, the maximum width is Elbegdorj, which means 4-5 mm, and the length is about 10 mm

(2 wear characteristics of the lintel of the plunger head. The wear here is smaller than that of the plunger head, and most of them are comb like fine grooves, which are also deep at the top and shallow at the bottom, thick at the top and fine at the bottom.

(3) the wear characteristics of the stop supply side of the plunger gradually reduce from the upper edge of the chute upward, and the wear width is about 5mm, which is milky white. At the same time, the edges of the stop supply side are blunt and rounded

(4) the wear characteristics of the lower shoulder of the plunger are very small here, and there are only short fine lines on the circumference of the shoulder

(5) the wear characteristics of the plunger sleeve are mainly near the oil inlet and return hole, and the oil inlet hole is larger than the oil return hole. The wear part of the oil inlet hole is near the centerline of the hole. The upper wear extends upward from the upper edge of the hole by about 6-7 mm, with a depth of about 0..027 mm, and the lower wear extends downward from the lower edge of the hole by about 4.5 mm, with a depth of about 0.015-0.017 mm. The wear width is about larger than the hole diameter

the wear of the surface near the oil return hole is mainly on the left, about.5mm wide, extending mm upward and mm downward, and the wear on the right side of the hole is very small

2. Identification of the plunger coupling. For the identification of the plunger coupling, the first is to conduct a general inspection by visual inspection to see whether there are obvious defects. For those who are qualified or cannot be determined, they can be further identified by testing

(1) visual inspection and identification: the head of the plunger, around the stop supply side or around the oil hole of the plunger sleeve can be seen with the naked eye, which is milky white due to wear. There is a clear feeling when scraping with a fingernail, the plunger or sleeve has rust, cracks, the top of the plunger or the stop supply side has peeling, etc. if there are any of the above defects, the plunger coupling is scrapped

(2) identify with the simple vacuum method, cover the top hole of the plunger with the right index finger, and slowly pull out the plunger with the left hand. At this time, the right index finger should feel suction. When it is pulled to about 2/5 of the total length of the plunger, release the plunger quickly, and at this time, the plunger will quickly return to the original position under the action of vacuum suction; It indicates that this plunger can be used continuously. Otherwise, it should be replaced with new parts or to be repaired

(3) the tightness test can be evaluated by using the injector tester. Install the plunger couple into the fuel injection pump body, install the oil outlet valve seat and other parts, do not install the oil outlet valve and the oil outlet valve spring, tighten the tight seat of the oil outlet valve, connect the tight seat end of the oil outlet valve of the fuel injection pump to the high-pressure oil pipe joint of the fuel injector tester, make the plunger in the maximum oil supply position, press the hand pressure rod of the fuel injector tester, increase the oil pressure to 22540 kPa, and stop pumping oil, Measure the time required for the oil pressure to drop from 19600 kPa to 9800 kPa. 7. The transmission chain of the compression testing machine should be filled with oil in time. The lubricating oil should be No. 50 mechanical oil. When filling, tilt the testing machine backward to make its base tilt up, and brush it with a brush dipped in oil on the chain of the detection part of the automobile safety belt coil spring under the base. The oil should not be excessive, so as not to flow downward. Its value should be in seconds. Otherwise, it is unqualified

3. Repair of plunger coupling

(1) the end face on the plunger sleeve is uneven. You can use grinding paste with a particle size of more than 600 to coat the thick glass and grind the upper end face. When grinding, keep the plunger sleeve vertical to the glass plate, gently drop the body with force, or the landing height and quality of the steel ball will directly affect the experimental results and be uniform. Rotate while moving, and constantly change the direction of rotation until the end face is smooth and free of scoring

(2) the blockage of the plunger in the plunger sleeve is generally common in the newly replaced plunger pair. The guide part of the plunger can be coated with engine oil for mutual research with the plunger sleeve. If it is too tight, it should be coated with polishing paste for mutual grinding. When grinding, use a bench drill or a hand drill to clamp the plunger, hold the plunger sleeve with your right hand, and move back and forth to grind each other. For the plunger with burrs on the top, use a fine oilstone with a particle size of 800, apply engine oil, tilt the plunger about 30 degrees, and gently rotate the plunger to remove burrs

(3) the plunger coupling with serious wear should be replaced with a new one

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