Of Hydraulic Piston Pump Noise Analysis
Liaoning Liaoning saddle Engineering Machinery Co., Ltd. Ma-dong
When a construction machinery used on the hydraulic piston pump in operation issued by excessive noise, this is the pump will be damaged symptoms.
Hydraulic Piston Pump (hereinafter referred to as pump) has the following seven kinds of noise.
⒈ pump noise inherent in
Pump noise is inherent in the original pump manufacturing technology to the present has not yet reached "robustness" requirements. Working methods of the pump, the pump rotation axis of each week, each pump plunger only have to make an oil absorption into the oil pressure cycle. Upon completion of the plunger suction pressure oil in the process of assignment, when the cylinder bore on the plunger chamber from the valve plate on the oil-absorbing window full of oil after the suction to the row of rotary oil transition, low-pressure oil-filled cavity of the plunger hole with the valve plate on a row of the high-pressure oil within the oil window, connected to the moment before (see Figure 1, to Kawasaki, Japan K3V pump valve plate, for example), behind the oil window of the high-pressure oil from a `second pre-boost Kong and the triangular cutting slots into the cylinder piston bore hydraulic chamber to increase chamber to form the impact of traffic intrusion (see Figure 2 left). As the plunger pulled out with the intrusion flow of pressurized, the pressure cylinder piston bore cavity with the row of rising to the hydraulic balance of the oil chamber, the plunger depressed to push the inclined plate, the plunger has experienced a downward movement oppression of oil into the cylinder of the assignment window, the plunger oil-drain resistance due to fluid impedance role in the discharge of oil a backlash by the system pressure resistance, the pressure cylinder piston bore cavity to form the overshoot. When the plunger to complete row of liquid, the cylinder plunger cavity hole spin a row of oil window, enter the valve plate of the cover areas, the cylinder piston bore cavity also I do not keep part of the emptying of the pressure overshoot dead volume of the pressure oil, due to valve plate on the angle of θ1 covered area, there is still a continued compression stroke plunger so the plunger cylinder bore cavity I kept pressure on the dead volume of the oil is more overshoot. When the cylinder piston bore cavity before rotating to the oil-absorbing window, to complete a release pressure process (see Figure 2 right), in order to facilitate the hydraulic cylinder piston bore cavity pressure to release oil-absorbing window with the low-pressure oil balance. Plunger cylinder bore cavity of the dead volume of high-voltage overshoot transient release the oil pressure cause a liquid explosive, this nine-hole cavity continuous plunger pressure transient liquid explosive is a stable high-pitched sound, each pump There are high or low liquid waterfall sound. Production plant around the world Hydraulic Pump valve plate in the transition region to take the pressure of various forms of noise reduction unit. From the traditional "triangle cutting trough" to "vent hole Dutch-style", "oblique trench-style" and so on, but they still not a satisfactory solution to the oil pump output pressure fluctuations in the fluid caused by the noise. For the construction machinery used in large displacement high-pressure pump pressure of mutation, dead volume of oil pressure relief area overshoot generated when the liquid explosive noise particularly strong.
⒉ cavitation noise
Hydraulic oil containing air bubbles when the oil bubble is inhaled with a cylinder bore, the piston in the cylinder hole in the oil hydraulic pressure into the cylinder with the oil stream surface emission window, in the high pressure, these bubbles will be in oil squeeze a sudden rupture, the size of the bubble is almost the same after the sudden high concentration of Bubble Collapse, it causes a strong gas explosion, the bubble burst produced by another high pitch noise, will be issued a strident The howling. This sharp ear-piercing noise is the pump pressure to follow the value of change. The highest pump output pressure, this noise decibels higher, when the pump after the pressure drops, such as the weak noise.
When the pump when the air inhaled a small amount of noise generated from the sound sounds like Katakata, somewhat like the voice of bearing damage. When the pressure rose to high-pressure pump, it creates a very strange heavy blow burst noise.
⒊ mechanical noise
Pump mechanical noise issue has ⑴ pump main body axis and the damage to the engine to take over office. ⑵ pump bearings office.
Such as pumps and the engine output shaft axis in different heart or top dead, flexible couplings and connections for broken bolts loose on the block will be noise.
If the bearing is damaged we will send out the voice of a continuous buzzing sound. As the pump speed increased, noise has also followed increases. Bearing damage, pump will appear tremble.
Pump mechanical noise is employing the ear can hear, the best way is to pump low-speed run-time, link up with industrial stethoscope or screwdriver in the pump all parts of the patient to listen,
⒋ sudden noise
Pump 1, but a sudden noise, it was necessary to immediately stop the pump running, this is the pump parts had been damaged.
Oblique axial plunger pump or a broken plunger pump swashplate sliding boots off, on the return drive fragmentation. This phenomenon is accompanied by the noise switch to circle the ring pump every time continuous loud noise impact. As it was setting off firecrackers in the pump body. Accompanied by population pressure hose pump P are the pulse of the phenomenon.
1 However, a sudden noise, the most critical is to not allow the hydraulic system pressure is rising because of pump parts cracked shell pieces of metal slag will be accompanied by pressure from the oil into the system. Pump a sudden noise is terrible, it is not only a pump damage, broken pieces of metal slag into a hydraulic system, but it is impossible to clear the hydraulic system caused by life-long harm.
⒌ pump repaired the noise generated by
Installation of pumps repaired after the noise than those without pre-pump repair of even greater reasons this occurs:
I pump suction hose hardening occurred in the installation of pumps, the pump has been a significant swing oil-absorbing side of hose, the hose and hard pipe to link the loose leak occurred at the air.
Ii Another assembly method is inappropriate in the front and rear pairs of even the pump (or so) two cylinder-hole symmetry, there has been resonant noise.
Iii is the replacement of bearings clearance exceeded, the pump bearings are a special type and high-precision level (large carrying capacity of bearings), can not use ordinary bearings.
Iv is the issue of quality replacement parts, spare parts with the precision between the lower grades, resulting in operating frequency resonance noise.
V is the cylinder with the valve plate matching between the friction pair arc bias, resulting in excessive leakage of oil between the friction pair noise.
Vi is a new inclined shaft pump pump valve plate and the old sliding-arc Road after the cover variable bias, resulting in high-pressure valve plate on the back of the mouth and pump the rear cover of flat area between the high-pressure leak, gas loss occurs the noise. New swashplate pump valve plate on the back of the rear cover and the old pump pressed districts will also give rise to similar failures and noise.
⒍ replacement of hydraulic oil pump after the emergence of the noise
This noise is the new replacement of the oil in the air did not fully escape, when the pharyngeal pumping into the air bubbles, then the outlet of the pump under high pressure, these bubbles will suddenly rupture, causing pressure gas waterfall sound, and the other The reason is the new replacement hydraulic oil of poor quality, longer storage, oil in the defoaming additive to oxidize, or oil in a variety of chemical additives incompatible with the adverse reaction, would not achieve the elimination of oil in the air effect.
Any brand of mineral hydraulic oil contains about 10% air. This is the way the air is two kinds of hydraulic oil in there, a bubble is in the form of oil, another benefit is based on molecules dissolved in the liquid form, is watching not be met. Increase the volume of the liquid is not obvious.
7, gradual onset noise
I pump in the process of long-term use, noise from small to big. Is the valve plate and the cylinder with flow occurred at about wear and tear, valve plate and cylinder with the arc flow is hydrostatic oil film balance, static pressure of the oil in the oil film containing metal particles, such as arises when the erosion wear, long-term erosion wear and tear will be In the valve plate of the arc have a certain width of the wear and tear on the region, with inner and outer flow of the window arc curve changes occurred Yuen, resulting in leakage from the micro to the large leakage of the process, there is also the throttle the noise from small to strong.
Ii pump suction side of the aging hose, air hose and hard pipe connection from the office has been inhaled, the air leak from zero to trace leaks and then to excessive leakage of a process, caused by inhalation of air pump "cavitation" This kind of noise are the noise from a small extension of working hours associated with the increased.
Some people think that I side-channel pumps are not oil-absorbing oil spills, there would be no air infiltration, this is the wrong understanding. From the principles of fluid mechanics and atmospheric pressure, when the pump does not work when the pump suction side and the atmosphere is zero pressure differential between the pump suction pipe flow of the liquid is not in equilibrium, there is no oil leakage. When the "variable pump" while working at the pump suction pipe when the fluid flow rate is faster when the slow state. When the pump "variable character" decided to pump the swing angle from zero to the maximum instantaneous change in angle, the pump suction pipe from the static state of the oil change to a fast-moving state of the time difference, the flow (liquid resistance) can not satisfy the pump demand, then produce a very large siphon phenomenon (that is, people talking about sucking force). Sucking pump suction force occurring phenomenon, also from the hose and hard pipe junction suck into the air and the emergence of cavitation.
When the pump flow rate of oil-absorbing excessive mouth tube, the (international standard for the steady flow state of 0.5m / s, absolute pressure of not less than 0. 8bars [1], the reality of the pump suction side of the peak flow rate, some up to 2. m / s turbulent state,). Pump suction side will be lower than atmospheric pressure is negative, then there is not enough pressure to speed up the flow into the pump rotating components, which could generate siphon phenomenon, siphon pump if there is the phenomenon that the life of the pump is of fate.
8, cavitation noise hazards
Pump in operation, where an over-current part of their local area (which is the pressure pump exports) for some reason, the absolute pressure of pumping the liquid down to temperatures at that time under the pressure of vaporization of liquid, the liquid will be vaporized in the area began to produce a large number of steam, the formation of bubbles, the bubble when the liquid contains a large number of streams flowing through the cylinder with high-pressure area outside the window, the bubble around the high-pressure liquid resulted in sharply reduced air bubbles, these bubbles have been pressed a sudden rupture, the role of the process will produce heat. According to the calculations, when the bubble is compressed to the pressure from zero 3000Psi (207Bar), the temperature can be raised to 1149 ℃. [2] heat to burn oil to generate resin-like substance, making oil the main reason for rapid oxidative degradation of deterioration.
In the bubble burst, while condensation of liquid particles at high speed filling holes, in this moment has a very strong impact on the role and to the impact of a high frequency of the fight against the metal surface, the impact of stress up to several tons per square inch, which species of cavity rupture of the energy release would be "nibbled" at the metal surface, like a sculptor with a hammer and chisel carving stones. When this occurred in the hydraulic impact of valve plate metal side walls, the bubble burst when you hit the cylinder wall, this time the instantaneous pressure of a great, and the resulting impact on the local hydraulic metal surface denudation. So that the surface of metal parts gradually formed pitting. Severe cases, cause the surface of small pieces of metal fall off, there pits (see Figure 3 Figure 4), a phenomenon known as cavitation. If the long-standing cavitation, pump life will be shortened.
Cavitation fault diagnosis methods:
I When the pump is high-pressure state, the glue used to hold the pump high-pressure pipeline looks, perceive the flow of the liquid inside the tubes if there was any vibration phenomenon.
Ii When the pump is high-pressure state, the port side of the pump Oil pump shell to listen to whether there is an explosion noise pops.
Iii open the hydraulic tank filler flap size excavator arm stretched flat, fast-rising bucket from the ground to observe the oil in the fuel tank if there are a large number of bubbles escape.
9 Conclusion
Any kind of noise, are harmful to the pump. Pump as long as the emergence of excessive noise, it is necessary for maintenance of the pump, do not wait until the pump failure after a thorough maintenance, then the loss may be too large.
References [1] German Rexroth Pumps Technical Information Installation Guide
[2] Parker Hydraulic Training Manual
Liaoning Liaoning saddle Engineering Machinery Co., Ltd. Ma-dong
When a construction machinery used on the hydraulic piston pump in operation issued by excessive noise, this is the pump will be damaged symptoms.
Hydraulic Piston Pump (hereinafter referred to as pump) has the following seven kinds of noise.
⒈ pump noise inherent in
Pump noise is inherent in the original pump manufacturing technology to the present has not yet reached "robustness" requirements. Working methods of the pump, the pump rotation axis of each week, each pump plunger only have to make an oil absorption into the oil pressure cycle. Upon completion of the plunger suction pressure oil in the process of assignment, when the cylinder bore on the plunger chamber from the valve plate on the oil-absorbing window full of oil after the suction to the row of rotary oil transition, low-pressure oil-filled cavity of the plunger hole with the valve plate on a row of the high-pressure oil within the oil window, connected to the moment before (see Figure 1, to Kawasaki, Japan K3V pump valve plate, for example), behind the oil window of the high-pressure oil from a `second pre-boost Kong and the triangular cutting slots into the cylinder piston bore hydraulic chamber to increase chamber to form the impact of traffic intrusion (see Figure 2 left). As the plunger pulled out with the intrusion flow of pressurized, the pressure cylinder piston bore cavity with the row of rising to the hydraulic balance of the oil chamber, the plunger depressed to push the inclined plate, the plunger has experienced a downward movement oppression of oil into the cylinder of the assignment window, the plunger oil-drain resistance due to fluid impedance role in the discharge of oil a backlash by the system pressure resistance, the pressure cylinder piston bore cavity to form the overshoot. When the plunger to complete row of liquid, the cylinder plunger cavity hole spin a row of oil window, enter the valve plate of the cover areas, the cylinder piston bore cavity also I do not keep part of the emptying of the pressure overshoot dead volume of the pressure oil, due to valve plate on the angle of θ1 covered area, there is still a continued compression stroke plunger so the plunger cylinder bore cavity I kept pressure on the dead volume of the oil is more overshoot. When the cylinder piston bore cavity before rotating to the oil-absorbing window, to complete a release pressure process (see Figure 2 right), in order to facilitate the hydraulic cylinder piston bore cavity pressure to release oil-absorbing window with the low-pressure oil balance. Plunger cylinder bore cavity of the dead volume of high-voltage overshoot transient release the oil pressure cause a liquid explosive, this nine-hole cavity continuous plunger pressure transient liquid explosive is a stable high-pitched sound, each pump There are high or low liquid waterfall sound. Production plant around the world Hydraulic Pump valve plate in the transition region to take the pressure of various forms of noise reduction unit. From the traditional "triangle cutting trough" to "vent hole Dutch-style", "oblique trench-style" and so on, but they still not a satisfactory solution to the oil pump output pressure fluctuations in the fluid caused by the noise. For the construction machinery used in large displacement high-pressure pump pressure of mutation, dead volume of oil pressure relief area overshoot generated when the liquid explosive noise particularly strong.
⒉ cavitation noise
Hydraulic oil containing air bubbles when the oil bubble is inhaled with a cylinder bore, the piston in the cylinder hole in the oil hydraulic pressure into the cylinder with the oil stream surface emission window, in the high pressure, these bubbles will be in oil squeeze a sudden rupture, the size of the bubble is almost the same after the sudden high concentration of Bubble Collapse, it causes a strong gas explosion, the bubble burst produced by another high pitch noise, will be issued a strident The howling. This sharp ear-piercing noise is the pump pressure to follow the value of change. The highest pump output pressure, this noise decibels higher, when the pump after the pressure drops, such as the weak noise.
When the pump when the air inhaled a small amount of noise generated from the sound sounds like Katakata, somewhat like the voice of bearing damage. When the pressure rose to high-pressure pump, it creates a very strange heavy blow burst noise.
⒊ mechanical noise
Pump mechanical noise issue has ⑴ pump main body axis and the damage to the engine to take over office. ⑵ pump bearings office.
Such as pumps and the engine output shaft axis in different heart or top dead, flexible couplings and connections for broken bolts loose on the block will be noise.
If the bearing is damaged we will send out the voice of a continuous buzzing sound. As the pump speed increased, noise has also followed increases. Bearing damage, pump will appear tremble.
Pump mechanical noise is employing the ear can hear, the best way is to pump low-speed run-time, link up with industrial stethoscope or screwdriver in the pump all parts of the patient to listen,
⒋ sudden noise
Pump 1, but a sudden noise, it was necessary to immediately stop the pump running, this is the pump parts had been damaged.
Oblique axial plunger pump or a broken plunger pump swashplate sliding boots off, on the return drive fragmentation. This phenomenon is accompanied by the noise switch to circle the ring pump every time continuous loud noise impact. As it was setting off firecrackers in the pump body. Accompanied by population pressure hose pump P are the pulse of the phenomenon.
1 However, a sudden noise, the most critical is to not allow the hydraulic system pressure is rising because of pump parts cracked shell pieces of metal slag will be accompanied by pressure from the oil into the system. Pump a sudden noise is terrible, it is not only a pump damage, broken pieces of metal slag into a hydraulic system, but it is impossible to clear the hydraulic system caused by life-long harm.
⒌ pump repaired the noise generated by
Installation of pumps repaired after the noise than those without pre-pump repair of even greater reasons this occurs:
I pump suction hose hardening occurred in the installation of pumps, the pump has been a significant swing oil-absorbing side of hose, the hose and hard pipe to link the loose leak occurred at the air.
Ii Another assembly method is inappropriate in the front and rear pairs of even the pump (or so) two cylinder-hole symmetry, there has been resonant noise.
Iii is the replacement of bearings clearance exceeded, the pump bearings are a special type and high-precision level (large carrying capacity of bearings), can not use ordinary bearings.
Iv is the issue of quality replacement parts, spare parts with the precision between the lower grades, resulting in operating frequency resonance noise.
V is the cylinder with the valve plate matching between the friction pair arc bias, resulting in excessive leakage of oil between the friction pair noise.
Vi is a new inclined shaft pump pump valve plate and the old sliding-arc Road after the cover variable bias, resulting in high-pressure valve plate on the back of the mouth and pump the rear cover of flat area between the high-pressure leak, gas loss occurs the noise. New swashplate pump valve plate on the back of the rear cover and the old pump pressed districts will also give rise to similar failures and noise.
⒍ replacement of hydraulic oil pump after the emergence of the noise
This noise is the new replacement of the oil in the air did not fully escape, when the pharyngeal pumping into the air bubbles, then the outlet of the pump under high pressure, these bubbles will suddenly rupture, causing pressure gas waterfall sound, and the other The reason is the new replacement hydraulic oil of poor quality, longer storage, oil in the defoaming additive to oxidize, or oil in a variety of chemical additives incompatible with the adverse reaction, would not achieve the elimination of oil in the air effect.
Any brand of mineral hydraulic oil contains about 10% air. This is the way the air is two kinds of hydraulic oil in there, a bubble is in the form of oil, another benefit is based on molecules dissolved in the liquid form, is watching not be met. Increase the volume of the liquid is not obvious.
7, gradual onset noise
I pump in the process of long-term use, noise from small to big. Is the valve plate and the cylinder with flow occurred at about wear and tear, valve plate and cylinder with the arc flow is hydrostatic oil film balance, static pressure of the oil in the oil film containing metal particles, such as arises when the erosion wear, long-term erosion wear and tear will be In the valve plate of the arc have a certain width of the wear and tear on the region, with inner and outer flow of the window arc curve changes occurred Yuen, resulting in leakage from the micro to the large leakage of the process, there is also the throttle the noise from small to strong.
Ii pump suction side of the aging hose, air hose and hard pipe connection from the office has been inhaled, the air leak from zero to trace leaks and then to excessive leakage of a process, caused by inhalation of air pump "cavitation" This kind of noise are the noise from a small extension of working hours associated with the increased.
Some people think that I side-channel pumps are not oil-absorbing oil spills, there would be no air infiltration, this is the wrong understanding. From the principles of fluid mechanics and atmospheric pressure, when the pump does not work when the pump suction side and the atmosphere is zero pressure differential between the pump suction pipe flow of the liquid is not in equilibrium, there is no oil leakage. When the "variable pump" while working at the pump suction pipe when the fluid flow rate is faster when the slow state. When the pump "variable character" decided to pump the swing angle from zero to the maximum instantaneous change in angle, the pump suction pipe from the static state of the oil change to a fast-moving state of the time difference, the flow (liquid resistance) can not satisfy the pump demand, then produce a very large siphon phenomenon (that is, people talking about sucking force). Sucking pump suction force occurring phenomenon, also from the hose and hard pipe junction suck into the air and the emergence of cavitation.
When the pump flow rate of oil-absorbing excessive mouth tube, the (international standard for the steady flow state of 0.5m / s, absolute pressure of not less than 0. 8bars [1], the reality of the pump suction side of the peak flow rate, some up to 2. m / s turbulent state,). Pump suction side will be lower than atmospheric pressure is negative, then there is not enough pressure to speed up the flow into the pump rotating components, which could generate siphon phenomenon, siphon pump if there is the phenomenon that the life of the pump is of fate.
8, cavitation noise hazards
Pump in operation, where an over-current part of their local area (which is the pressure pump exports) for some reason, the absolute pressure of pumping the liquid down to temperatures at that time under the pressure of vaporization of liquid, the liquid will be vaporized in the area began to produce a large number of steam, the formation of bubbles, the bubble when the liquid contains a large number of streams flowing through the cylinder with high-pressure area outside the window, the bubble around the high-pressure liquid resulted in sharply reduced air bubbles, these bubbles have been pressed a sudden rupture, the role of the process will produce heat. According to the calculations, when the bubble is compressed to the pressure from zero 3000Psi (207Bar), the temperature can be raised to 1149 ℃. [2] heat to burn oil to generate resin-like substance, making oil the main reason for rapid oxidative degradation of deterioration.
In the bubble burst, while condensation of liquid particles at high speed filling holes, in this moment has a very strong impact on the role and to the impact of a high frequency of the fight against the metal surface, the impact of stress up to several tons per square inch, which species of cavity rupture of the energy release would be "nibbled" at the metal surface, like a sculptor with a hammer and chisel carving stones. When this occurred in the hydraulic impact of valve plate metal side walls, the bubble burst when you hit the cylinder wall, this time the instantaneous pressure of a great, and the resulting impact on the local hydraulic metal surface denudation. So that the surface of metal parts gradually formed pitting. Severe cases, cause the surface of small pieces of metal fall off, there pits (see Figure 3 Figure 4), a phenomenon known as cavitation. If the long-standing cavitation, pump life will be shortened.
Cavitation fault diagnosis methods:
I When the pump is high-pressure state, the glue used to hold the pump high-pressure pipeline looks, perceive the flow of the liquid inside the tubes if there was any vibration phenomenon.
Ii When the pump is high-pressure state, the port side of the pump Oil pump shell to listen to whether there is an explosion noise pops.
Iii open the hydraulic tank filler flap size excavator arm stretched flat, fast-rising bucket from the ground to observe the oil in the fuel tank if there are a large number of bubbles escape.
9 Conclusion
Any kind of noise, are harmful to the pump. Pump as long as the emergence of excessive noise, it is necessary for maintenance of the pump, do not wait until the pump failure after a thorough maintenance, then the loss may be too large.
References [1] German Rexroth Pumps Technical Information Installation Guide
[2] Parker Hydraulic Training Manual






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