1. fault phenomena and analysis
There are various forms of the inclined disc axial piston pump, but the principle of general structure is basically the same. The common shaft pump is used as an example to illustrate its structural characteristics and common fault causes.
(1) structure
The plunger pump is mainly composed of plunger, cylinder, cylinder, drive shaft, drive shaft, slanting disc, return plate, spring and servo variable mechanism. The drive shaft passes through a slanted disc with tapered bearings on both ends. The rotating cylinder is evenly distributed in the circle (usually 7 or 9), and the rotating cylinder is supported on the drive shaft through the drum shaped spline. The plunger tail is supported. With a sliding boot, the part is pressed on the slanting disc through a return plate and a spring. The inclined disc is mounted on the bottom of the hydraulic pump shell through a pair of bearings and can rotate in a certain angle range. As the drive shaft drives the cylinder body rotation, the plunger is rotated on the one hand and the other is axially moving. The axial pump usually comes out because of the characteristics of the above structure transmission. The following failure:
1) the contact face wear of the cylinder body and the disks. The size of the normal wear of the face depends on the strength of the compression spring force in the cylinder and the state of the hydraulic lubrication. In the case of small change in the lubrication condition, the normal wear of the cylinder body and the end of the flow disc has little effect on the seal condition of the plunger pump. The oil liquid has repeatedly scoured the high pressure and low pressure overflow area of the flow plate to make its deep and shallow grooves to increase the pump leakage and seriously lose its working capacity. The bearings at both ends of the drive shaft are easily worn after a certain time, resulting in axial and radial runout gaps. The body directly acts on the flow plate. Because of repeated impact on the local surface of the flow plate, it is easy to produce fatigue exfoliation and distortion. The stripped metal fragments are mixed on the surface of the two relative motion or into the plunger cavity, forming serious particle wear, and pulling the cylinder with the flow plate, the plunger surface and the cylinder hole out of the deep groove, causing the pump to pump the pump. The oil leakage is increased or the working capacity is completely lost.
2) the wear of the plunger. The piston has a high precision for the transmission accuracy and a strong sensitivity to the hydraulic oil pollution. A little carelessness will lead to the early wear of the plunger and the local damage to the surface. After a period of time, the plunger pump is worn and the joint clearance increases obviously because of the wear of the transmission mechanism. The additional inertia impact will increase as a result. At the end of the plunger, the plunger is skewed and worn in motion. When the hydraulic oil temperature rises to higher than the normal value, the lubrication condition of the plunger is deteriorated by the dry friction when the heavy load of the hydraulic oil is above the normal value. The cylinder plug can be killed in the rotating cylinder in a moment under the impact load, and the light may draw the plunger research. After grinding and repairing, the plunger is locked in the cylinder body, and the slipper and the return disk are broken, causing the cylinder block and plunger to be scrapped.
3) the wear of the tail of the plunger and the slipper, slipper and slanted disc. The wear degree of the slipper and the slanted disc mainly depends on whether the lubrication small holes in the plunger tail often remain unblocked. This is the key to ensure the formation of the boundary oil film between the inclined plate and the slipper. As the diameter of the small hole in the plunger tail is very small, the metal impurities and the oil pollution will destroy the original. Some lubrication states speed up the wear between slipper and plunger tail and slipper and slanting disc. The slipper wears a continuous reaction after the slipper is worn, and the impact return plate makes it wear out larger elliptical holes. The loose return plate has repeated impact on the end of the plunger and makes it wear out, thus producing greater noise.
4) the servo variable mechanism is not working, the induction piston hairpin, the pressure adjusting spring break. This will make the angle of the inclined disc change or change cannot adapt to the need of the load change, cause the heat of the pump and system, the invalid loss increase. In the process of rotation, the angle enlarging inclined disk often collided with the hydraulic pump shell, and the deep groove mark was hit on the back of the shell and the back plate. The vibration of the servo valve and the wear of the components in the valve were artificially accelerated, so the original working performance of the plunger pump was damaged.
