Noise analysis of several plunger pumps

1. Mechanical noise
The primary place where the pump announces mechanical noise is the coupling bearing between the pump spindle and the engine. Mechanical noise may occur if the pump spindle is different from the engine output shaft or is not centered or capped, the elastic coupling is damaged or the bolt is loose. Bearing damage will be announced after a series of "gurgle" sound, the higher the speed of the pump noise, the higher the pump will be, together with a pump will appear to shiver.
The mechanical noise of the pump can be heard by the human ear. When the pump is running at a low speed, it can be heard by the industrial stethoscope or through screwdriver in all parts of the pump.
2. Cavitation noise
Rich bubble when the hydraulic oil, the oil with air bubble drawn into the cylinder hole of piston in the cylinder hole squeeze oil into the oil discharge valve plate cylinder body window, under the effect of high pressure these bubbles will be squeezed by Russia but break, intrusive almost the same bubble was sudden breaking again after high pressure oil enrichment, would amount to a small gas explosion. Another high - pitched noise that occurs when a bubble bursts will announce a sharp, sharp hissing sound. This sharp, sharp noise changes with the pump's pressure. The noise is also highest when the pump output pressure is at its peak, and it weakens when the pump pressure is reduced.
When the pump inhaled a small amount of air, the noise sounded like "clack, clack," a bit like a damaged bearing. When the pressure of the pump rises to high pressure, there will be a very perverse crack burst of noise.
3. Burst noise
In the inclined shaft of pump plunger cracking or swash plate pump plunger sliding boots drops, return the disk rupture sudden noise, is the pump every turn a barrage of loud clattering noise, as the same set off firecrackers.
Once the pump presents a sudden noise, it is necessary to stop the pump immediately to prevent the further expansion of the problem. The most crucial is not allow hydraulic system pressure rise, due to the pump shell parts broken pieces of the metal clinker will follow pressure oil into the system, not be removed completely, will be a lifelong harm to hydraulic system.
4. Inherent noise
Inherent noise to clarify pump to produce skill now haven't reach the request, the pump works, the pump spindle each rotation for a week, not a plunger pump are an oil absorption to pressure oil circulation. Plunger in the finished oil suction, pressure distribution of flow process, the overshoot of the plunger cylinder body hole cavity die in high-pressure oil in a flash will constitute a liquid explosive pressure relief, the plunger pressure transient liquid explosive hole cavity is a safe, high tone sound, each pump there is high or low fluid organ sound. Various kinds of noise reduction units are adopted in the pressure transition zone of the distribution disc in hydraulic pump production plants around the world. From traditional "triangle saving groove" to "unloading hole" and "oblique groove", the fluid noise caused by pump output pressure oil shaking has not been solved satisfactorily. As for the high pressure pumps with large displacement pressure changes in engineering machinery, the liquid explosion noise is stronger when the excess oil pressure is discharged in the dead volume area.
5. Oil change noise
Factor: the air in the new replacement oil does not escape sufficiently. When the pump inhales the bubbles, the bubbles will contract and break down in a high pressure effect at the pump outlet. The newly replaced hydraulic oil is of poor quality and has been stored for a long time. Oxidation of defoaming agent in oil solution or adverse reactions of various chemical additives in oil products have failed to eliminate the air in oil products.
6. Patched noise
The noise after the pump repair is greater than that before the repair, and the factors are as follows: when the pump oil suction hose is hardened and the device is greatly shaken, the joint between the rubber hose and the hard pipe will loosen and leak gas. In case of improper installation method, the front, back or left and right cylinder bore in the dual pump are symmetrical, and the resonance noise will appear. The noise also occurs when the bearing clearance overruns with respect to the replacement. The precision level of the pump bearing is huge bearing capacity bearing, not general bearing; The quality of the replacement parts is in doubt, and the low precision level of the parts will result in the occurrence of operating frequency resonance noise. Correspondingly, the cylinder body and the flow distribution plate pair conflict subarc offset, which will attack the excessive noise of oil leakage between the conflict subunit. The deviation of the new distributor disc and the variable sliding arcway on the back cover of the old pump will result in the leakage of the plane in the high pressure area between the high-pressure mouth on the back side of the distributor disc and the high pressure area between the back cover of the pump, and the burst gas loss noise. The same noise will appear on the back side of the new distribution disc of the inclined disc pump and on the back cover of the old pump.
7. Cavitation noise
Pump in operation, if the flow of some parts such as pump discharge liquid must be pressure down to a temperature vaporization pressure, the liquid will vaporize attack many steam bubbles, when loaded with a lot of bubbles in the liquid flowing through the cylinder valve window to the outside of the high, high pressure liquid will reduce bubble rapidly until Russia but break, high temperature and attack. The high temperature makes the oil burn, produces the resinous material, and accelerates the oxidation and transformation of the oil.
Condensation of air bubbles break, liquid particle filling holes at high speeds, in a flash will impact metal appearance at high frequency, great impact stress, can "eat" metal appearance, like carve a hammer or chisel carved stones are the same. When the hydraulic shock attack at the edge of the valve plate of metal wall, bubble bursting hit the cylinder wall instantaneous pressure is great, has the erosion effect of metal appearance, make the metal parts gradually form pitting appearance, serious when they make the metal appearance small drops, presents small hole, if the air-pocket scene exist for a long time, great harm.
The methods for distinguishing cavitation faults are as follows:
(1) when the pump is in a high pressure state, hold the high-pressure rubber hose of the pump by hand to perceive whether there is vibration when the liquid in the pipeline is active. When the pump is under high pressure, in the pump suction side listen to the pump shell is there a crack blasting noise.
(2) open the oil cap of the hydraulic oil tank, excavate the manipulator arm and the bucket pole, and lift the bucket from the ground quickly to observe whether there are many bubbles escaping from the oil in the tank.
(3) as long as the pump presents overspend noise, the pump shall be repaired in time. If the pump fails to repair after failure, the loss will be too large.
8. Asymptotic noise
(1) in the long service of the pump, the noise is from small to large. Factor is the distribution of flow valve plate and cylinder surface wear, valve and valve plate surface and cylinder surface static pressure oil film is balanced, rich in metal particles in the oil film will attack erosion wear, long time of erosion wear will flow on the plate surface, constitutes a width must be wear area, make the flow matching window onset of inner ring and outer ring of round curve change xuan, lead to leakage from light to heavy, saves the noise is from small to large.
(2) the oil pump suction hose aging, air is sucked from the linkage between the hose and hard tube, the air will be leaked from zero to trace leaked to excessive leakage, pump suction air after the "air pockets in the composition of noise with the extension of working hours from small to large.
If think the side pipe of pump suction port does not leak oil, won't have air infiltration person, this is fault.
When the flow rate of the oil pump suction pipe mouth overruns, oil pump suction mouth side certainly will be lower than atmospheric pressure and negative pressure, at the moment does not meet the pressure to speed up the flow into the pump rotating components, siphon will attack, the pump is killed.