what causes hydraulic pump whine made in china

Every hydraulic pump makes some noise. If all is well with a pump, then this noise stays more or less the same. However, if something goes wrong with the pump or its connected system parts, then you may start to hear sounds that you haven"t heard before.

The fluid that flows through your system needs to move at a smooth and even rate. The pump has to deliver the fluid at a specific flow for things to work.

If something prevents the fluid from achieving and maintaining its optimum flow, then your pump may start to make unusual noises. For example, you may hear a high-pitched whine coming from the pump. This can be a constant or intermittent sound.

If your pump whines constantly, then you may have a cavitation problem. Here, the pump can"t deliver its fluid at the right volume or rate. There isn"t enough fluid coming through the pump"s suction line.

In some cases, this is a sign that your pump"s motor is on the wrong setting. So, the pump itself is working at the wrong speed to create the right flow.

A hydraulic pump might get noisy if one of its parts or connections has a problem. A faulty or failing pressure control, bearing, valve, seal, or coupling can make a noise you haven"t heard before.

In some cases, you may hear vibrating clunks as your pump works if you have a problem with a connecting pipe. A loose seal or connector might allow the pipe to move. It then passes vibrations along to the pump itself.

While some noise problems are easy to fix, some are a sign that your pump is close to the end of its working life. Sometimes, this is due to natural wear, usage, and age. However, in some cases, minor problems cause more widespread damage if you don"t fix them quickly.

For example, if you"ve had cavitation problems for a while, then your system may not have been getting the lubrication it needs; it may have overheated regularly. Even if you fix the cavitation issue, you may be left with a damaged pump that needs a more significant repair, rebuild, or replacement.

So, while new sounds or an increase in operating noise don"t necessarily mean that you have a serious pump problem, you should investigate any unusual noise. Typically, this is a sign that something isn"t working right.

A minor problem in your system could go on to cause significant damage. For an expert diagnosis, contact Quad Fluid Dynamics, Inc. Ourhydraulic pump repair and rebuild servicewill get your pump running smoothly and efficiently again.

Pump cavitation is first and foremost caused by insufficient flow. This happens when the volume of fluid being supplied doesn’t meet the demands of the hydraulic circuit, and the pressure at the suction end of the pump isn’t sufficient. This leads to the absolute pressure falling below the vapor pressure of the liquid, which leads to air bubbles being formed. These tiny bubbles implode as they pass through the system, creating shockwaves and causing pump vibrations.

The process of these bubbles forming and collapsing is done with a great deal of force, and leads to eventual metal erosion inside the pump. The mechanical damage caused by cavitation can have irreversible impacts on system components and may possibly lead to complete failure. Cavitation happens only on the suction side of the pump, and may be caused by a series of different malfunctions, including:

Cavitation is typically characterised as a high-pitched whining or screeching sound, and in some extreme cases, can present itself as a loud rattling sound. Whilst these hydraulic pump whine noises are generally the most obvious telltale signs of cavitation, other symptoms to look out for also include:

By design, hydraulic pumps contain a miniscule amount of air which allows space for the hydraulic fluid to heat up and expand. However, too much air in the pump can cause serious issues – this is known as aeration.

Aeration in a hydraulic pump occurs when there is an air leak in the suction line. When outside air enters the pump through a damaged connector, loose pump seal, pipe fitting, or any other damage, it gets drawn into the pump’s hydraulic fluid supply. This unwanted air quickly gets dissolved into the hydraulic fluid and leads to contamination.

Contaminated hydraulic fluid can have serious implications for the system, as the excess air means that it cannot conduct heat as efficiently and can cause the fluid to foam. This can lead to overheating and in some cases, a substantial decrease in power. Aeration may happen on both sides of the pump, and has several causes including:

Similar to cavitation, aeration is usually indicated by a sudden change in noise, which can sometimes make it difficult to differentiate between the two causes However, aeration tends to produce a more erratic low-pitched ‘rumbling’ or ‘rattling sound, as opposed to the more consistent whining noise of cavitation.

Excessive or erratic hydraulic pump noise is a symptom of malfunction that could cause damage or accelerated wear if not addressed quickly and correctly. While it’s never nice to hear strange noises emitted from your pump, different forms of noise, which are related to different faults can provide valuable clues that can help you to diagnose your problem and get it fixed before it turns into something major.

So it pays to know what different pump noises mean and with practice you can quickly distinguish between the normal operating sounds and signs that something is wrong. In this article, we’ll talk about what causes some of these sounds, so you can identify them.

A constant hissing sound is indicative of a relief valve that is set too low or is stuck open and is continually releasing pressure. An erratic whistling sound is a symptom that a relief valve is set incorrectly or is damaged. It is common for pump settings to be changed carelessly or inadvertently - sometimes to overcome other issues with the hydraulic system - sometimes due to a lack of understanding of the correct operating conditions, so include this in your regular checks. In addition to noise problems, relief valve damage can be accompanied by slamming of actuators, stalls and excessive heat generation.

Noise issues are just one symptom that gives you a clue when things go wrong with your hydraulic pump. There are several other issues to know and understand, which could help you to identify pump problems quicker. Which means you can sort them out sooner - potentially saving big money down the road. These include heat problems, pressure problems and flow problems.

Among the various types of hydraulic pumps, the vane pump is a type of pump capable of achieving lower noise due to smooth operation and small flow pulsation. However, with the development of the vane pump to high pressure and high speed, noise has become a prominent problem. In the late 1950s, a vane pump with a pressure rating of 14.0 MPa appeared in foreign countries with a noise of about 75 DB. Since 1960, foreign countries have begun to pay attention to the research of reducing vane pumps. By the end of the 1970s and the mid-1980s, a series of low-noise vane pumps with excellent performance have emerged, and the noise can generally be controlled below 65DB. Among them, Japan Oil Research"s PV2R series vane pump, even as low as 51-62DB, has reached the level of noise lower than the same power motor.

1. During the operation of the pump, friction, collision, etc. between the blade and the stator curve surface cause noise. The main reason for the friction between the blade and the stator is that the pressure of the blade liquid is not well balanced, and the force at the bottom is too large, which is caused by the contact between the top of the blade and the surface of the stator. There are two reasons for causing the blade to collide with the stator: one is caused by the stator curve changing the blade motion state and the vibration caused by the impact; the other is the unstable blade motion caused by the machining accuracy error of the part. of. The impact of the blade on the stator is the most basic cause of the noise generated by the vane pump, so it is very important to study the characteristics of the stator curve.

The above 4 points are the common causes of the noise of the vane pump. Users can check the noise problem one by one and solve it in time to avoid causing greater losses. If technical doubts can be consulted, Taizhou Yongchang Hydraulic Machinery Co., Ltd., we Will provide quality technical support.

Most ship’s hydraulic systems cry out with a noise where this becomes specifically unbearable for those who are in the vicinity.  At this moment, shipping is busy combating exhaust gas emissions.  While there are no regulations or any stringent requirements to be met for Noise emissions, the shipping industry can soon witness it.

There are some tankers and other ships with hydraulic driven cargo pumps and some high capacity fuel oil transfer pumps which are hydraulic driven that cause significant noise during their operation.

The dominant source of noise in hydraulic systems is the pump.  The hydraulic pump transmits structure-borne and fluid-borne noise into the system and radiates air-borne noise.All positive-displacement hydraulic pumps have a specific number of pumping chambers, which operate in a continuous cycle of:

These separate but superimposed flows result in a pulsating delivery, which causes a corresponding sequence of pressure pulsations.  These pulsations create fluid-borne noise, which causes all downstream components to vibrate.The pump also creates structure-borne noise by exciting vibration in any component with which it is mechanically linked, e.g. pump casing, tank top, pipings, bulkheads etc.  The transfer of fluid and structure induced vibration to the adjacent air mass results in air-borne noise.

While fluid-borne noise attributable to pressure pulsation can be minimized through hydraulic pump design, it cannot be completely eliminated.  In large hydraulic systems or noise-sensitive applications, the propagation of fluid-borne noise can be reduced by the installation of a silencer.  The simplest type of silencer used in hydraulic applications is the reflection silencer, which eliminates sound waves by superimposing a second sound wave of the same amplitude and frequency at a 180-degree phase angle to the first.

The propagation of structure-borne noise created by the vibrating mass of the power unit (the hydraulic pump and its prime mover) can be minimized through the elimination of sound bridges between the power unit and tank, and the power unit and valves.This is normally achieved through the use of flexible connections i.e. rubber mounting blocks and flexible hoses, but in some situations it is necessary to introduce additional mass, the inertia of which reduces the transmission of vibration at bridging points.

The magnitude of noise radiation from an object is proportional to its area and inversely proportional to its mass.  Reducing an object’s surface area or increasing its mass can therefore reduce its noise radiation.For example, constructing the hydraulic reservoir from thicker plate (increases mass) will reduce its noise radiation.The magnitude of air-borne noise radiated directly from the hydraulic pump can be reduced by mounting the pump inside the tank.  For full effectiveness, there must be a clearance of 0.5 meter between the pump and the sides of tank, and the mounting arrangement must incorporate decoupling between the power unit and tank to insulate against structure-borne noise.The obvious disadvantage of mounting the hydraulic pump inside the tank is that it restricts access for maintenance and adjustment.If hydraulic system noise remains outside the required level after all of the above noise propagation countermeasures have been exhausted, encapsulation or screening must be considered.

Vibration and noise are two common phenomena in the operation of hydraulic components including hydraulic pump. Vibration is the inherent characteristic of elastic material. Noise comes from vibration. The animal that causes noise is called sound source, so the control of noise comes down to the control of vibration.

With the high pressure, high speed and high power of hydraulic technology, vibration and noise have become prominent problems in the development of hydraulic technology. Because the vibration affects the working performance and service life of the main engine and the system, and the noise not only causes human hearing loss, but also distracts the operator"s attention, and is more likely to submerge the alarm signal, causing personal and equipment accidents. Vibration and noise has become an important index to measure the performance of hydraulic pump.

(l) Theoretical analysis shows that the fundamental reason of the vibration is the size of the vibration element and the exciting force. The vibration can be measured by accelerometer instead of microphone in sound level meter. The main way to prevent, reduce and eliminate the vibration of hydraulic components and devices is to eliminate or reduce the excitation source (force), and reasonably design and match the inherent parameters of hydraulic components and devices.

(2) The generation, radiation and types of hydraulic noise can be seen from the following table. Hydraulic pump is the main noise source in all components of hydraulic system, which is called primary noise source. Other components, such as oil tank and pipeline, make little noise and are not independent noise sources. However, mechanical and liquid noise generated by pump and hydraulic valve will stimulate them to produce vibration, thus producing and radiating strong noise This kind of noise source is called secondary sound source. The noise of hydraulic system is the superposition of primary and secondary noise sources. Therefore, the vibration and noise control of hydraulic device should be considered from two aspects: component noise and device vibration noise. Obviously, reducing the noise of the hydraulic pump is the main way to control the noise of the whole hydraulic system.

The noise produced by hydraulic components and systems mainly includes mechanical noise and fluid noise. For hydraulic pumps, mechanical The noise includes the noise caused by the bearing vibration, the mechanical collision noise caused by the collision between the parts in the pump, the noise caused by the poor lubrication and friction between the surfaces of the relative moving parts, the noise caused by the vibration of the whole hydraulic pump as a mass spring system, and so on; the fluid noise includes the cavitation noise caused by the oil suction cavity, the vortex separation noise caused by the change of the flow channel, and the load The sound of pressure shock caused by sudden change or trapped oil, the sound of pressure pulsation caused by flow pulsation, etc.

Noise control is an important part of environmental protection and one of the quality evaluation indexes of hydraulic products. The noise health standard for industrial enterprises, which was published and implemented in China in 1980, is based on A-level (noise measured by A-weighted network in sound level meter). The allowable noise value of hydraulic pump in China is in JB / T 7041-2006_ JB / T 7039-2006 and JB / T 7042-2006 stipulate: for example, under the rated pressure and speed, the noise value of gear pump with rated pressure of 10-25mpa and displacement of more than 25-500ml / R shall be ≤ 85dB (a); the noise value of fixed vane pump with rated pressure of 16-25mpa and displacement of more than 50-63ml / R shall be ≤ 78dB (a). The noise value of swash plate axial piston pump with displacement > 25 ~ 63ml / R should be ≤ 85 dB (a).

(4) Noise measurement in order to analyze the noise of hydraulic pump, analyze the noise source and take appropriate control measures, it is necessary to measure the noise of hydraulic pump.

① The commonly used noise testing instruments include sound level meter, frequency analyzer and recording instrument. Sound level meter is a kind of noise measuring instrument which is widely used and suitable for the field. It can measure not only the sound pressure level and sound level of noise, but also the frequency analysis by filter, and use accelerometer instead of microphone to measure vibration. According to the measurement accuracy and application, the sound level meter can be divided into three types: ordinary type, precision type and pulse precision type. The noise measurement of hydraulic components and devices usually adopts the precise sound level meter. According to the display and reading methods, the sound level meter can be divided into pointer type and digital type (see Figure r for the appearance). The operation method and precautions of the sound level meter can refer to the product manual.

c. If the distance between two noise sources is close (such as hydraulic pump and its driving motor), the measuring point should be close to the measured noise source (0.2m or 0.1M).