Air compressor noise analysis and control

The technical center of Anshan Oilless Air Compressor Co., Ltd. was transformed into 4031 pieces of Liaoning and the noise was controlled according to the analysis results, and the control effect was evaluated.

The 210.057 air compressor produced by Anshan Oilless Air Compressor Co., Ltd. is too noisy due to the noise of 8,48, which can not meet the user's requirements. 65 The demand for low-noise air compressors on the market is large, especially in hospital residents. Air compressors in areas such as districts and educational districts are more stringent in noise requirements. To this end, the noise source and its characteristics of the air compressor are analyzed, and the sound insulation is controlled by the sound insulation box, and the need for ventilation and cooling is taken into consideration. The air compressor that achieves the expected noise source of the air compressor is a multi-source generator. The noise is mainly the intake noise, exhaust noise and mechanical noise.

Intake noise The intake air intermittently draws in air, generating pressure pulsation and transmitting it into the air to form aerodynamic noise. With the intermittent opening of the air intake valve of the air compressor cylinder, when the airflow is intermittently sucked into the cylinder, pressure fluctuations are generated in the vicinity of the air inlet, and are radiated from the air inlet in the form of sound waves, thereby generating intake noise.

When the exhaust noise gas is intermittently discharged from the cylinder valve, the airflow generates noise caused by the disturbance; the high-pressure gas generated by the air compressor enters the gas storage tank through the pipeline, and the pressure pulsation is generated as the displacement of the exhaust gas is generated, so that the pipeline is generated. The vibration forms noise; when the compressed gas passes through the small hole of the valve, it is injected at the speed of sound, and the valve noise is formed at the outlet of the impact valve or the outlet of the valve. The size of the valve noise is related to the shape and size of the valve and the pressure and flow of the compressed air. When the air compressor is vented, the volume of the compressed air suddenly expands and enters the atmosphere at a high flow rate, resulting in a strong exit at the outlet of the pipe. Eddy current noise, although it is intermittent, but because of its high frequency and sound level, it has a great impact on the surrounding environment.

Mechanical noise Mechanical noise is mainly caused by friction and uneven transmission of force between mechanisms. When the air compressor is running, many components rotate and reciprocate rapidly, causing frictional shocks and causing noise generated by vibration of the machine. There are mainly piston reciprocating motion and cylinder wall friction, so that the noise spectrum wall of the cylinder Talc 22 is inherently buccal + strong vibration, the curved rod connecting rod and the crossfire, etc., also occurs during the movement, the friction of the bearing, the vibration and the noise of the external body including the machine The vibration and noise of the shell support structure and the base; the vibration and noise of the cooling system also include the noise emitted by the vibration of the casing caused by the noise imbalance of the bearing during the operation of the motor; the noise source parts of various compressors and their transmission paths are generally It is similar, 1 is the noise source of the live cold compressor and its transmission path.

1. Cylinder 1 live cold 3. Connecting rod crankshaft. , 4. Cooling wind by 5. Motor 6. Gear pair 7. In-cylinder gas pressure change 8. Words, 1 boat 9. Not balanced, sexually swaying machinery, also the animal's squeak and shock. Turbulent noise 2. 蚪哄 +13 channel sound (4) cooling air 玷 meshing rushing out 彤 intake valve cylinder gas pulsation and 18. gas through the sputum idle thirsty sound 9. body. Qu, 20. Motor mechanics 25. Cylinder. Cylinder 26. The body. The structure of Qufupo is from the snoring 27. The breathing hole is vented by 28. The casing is drilled, and the shell structure is made of 3 peppers. Cylinder. The intake wheel system is clever, the rim system is from the pepper and the boat. The gas is swaying. 4. The gas is like a pepper and the 42-station tank is 43 cans. The resonance sound 45 is connected to the wide system 46, and the air is injected into the atmosphere. 2. The characteristics of the air compressor noise are analyzed. The noise rate of the air compressor is relatively wide. The main peak frequency of the influential is between 202000 and 2 is 2 The noise cheek spectrum of the double 0.057 plow compressor was measured by a double cheek analyzer. The range of frequency that can be frequencyd by 2 is wide, and there is a large peak of the garbage at the center of about 400, and the frequency of the compressor is reduced as the size of the compressor increases or if the speed of the machine decreases.

1 Gas pressure and scrambling in the cylinder. When the air sequencer is working, the pressure of the flying body in the cylinder changes periodically. This gas pressure change produces the gas sound in the cylinder, and at the same time, activates the cold cylinder and cylinder.

Vibration of components such as connecting rods and the body. Rushing and emitting sound, this is the source of air compressor noise. Analysis of the gas pressure of the cheeks, frog research and control of the six aspects of the sound and solid sound. The gas pressure cheek is a kind of discrete chopping spectrum. Its base cheek is the speed of the frog air compressor, and the cheeks are an integral multiple of the base cheek. General + force cheek please 4 divided into a cheek segment, I thought that the low frequency 艮 2 training this is the high cheek 虬 3 between the two 为 is the middle cheek segment. It must be said that the boundaries of this section are not very strict, and the diameter of the dry cylinder is small. When the rotation speed is high, the boundary cheek rate is quietly high, and vice versa. Each cheek segment has its own characteristics.

0 low buccal segment contains the first few harmonics from the base cheek sweat, in which the gas pressure level reaches a considerable level of ,, they are mainly due to the internal and external discharge force of the machine and the size of the work surface. It was decided that it caused low cheek forced vibration of parts such as gas shears. Due to the solidity of the cylinder and other parts, the cheek-wei is far and far, and the buccal rate is disturbed. Therefore, the buccal noise radiated from the components such as the cylinder is low. The periodic variation of the working process in the buccal segment of the buccal segment The characteristics gradually disappear. The buzz is controlled by the impact of the output. From the separation, please change to the continuum, the pressure level decreases with the increase of the buccal string, and the decrease is mainly controlled by the value of the gas pressure curve, which is the value of the high pressure rise rate. The heart, the heavier, the pressure level The smaller the trend as the frequency string increases, the smaller the cheek elimination curve is. For example, in a rotary retracting machine, there is often a closed capacity, causing a sudden change in gas pressure, resulting in a large mountain value of 3, which causes a large noise in the middle collar.

3 The height of the buccal section of the high buccal segment is mainly determined by the maximum value of the acceleration of the dry pressure rise, which will cause the cylinder to resonate. When the air column resonance is intensified, it will cause a zigzag pressure wave to appear on the work. The resonance frequency is illusory as the 进气4 air compressor air intake sound is normal, the sound of the intake air squeaks in the idle, but due to the air intake system At the Ximen population, at the speed of the 荇 or the force is also excited, it, the excitation source of the forced vibration of the column, the frequency of the excitation function to be affected, and the special bamboo of the intake manifold system. The air column's fixed rate characteristic is a cheek sound characteristic.

When the valve is closed for a long time, it will cause the airflow to reverse, which will also stimulate the 0-excited vibration of the elastic valve. The air valve noise is in the attitude of the air intake + through the cylinder. The cylinder head and the pipe are passed out.

3 Intake, the gas of the sonar tracheal enthalpy, the pulsation of the pulsation into the force, will lead to the body sound radiation at the mouth of the compressor, that is, the sound of the intake hum. The inlet of the air is reduced by the air inlet of the air, so the incoming noise is often 50 compared with the noise of the upper sound source of other parts, so the air compressor hum is the total hum of the compressor, mainly section. 4 is the air compressor noise, 3 valve piece, the vibration vibration sound is too large for the dry elastic valve or no lift, the limiter's tongue valve, the valve will appear vibration, the generation of the cheek Wei approximation, etc. 1 The inter-frequency + chattering of the valve piece, the lack of elastic system will also increase the number of times the 打1 hit valve seat becomes a lift limiter, thereby increasing the click. The circumference 3 is the air valve, the intake noise caused by the vibration, the sound speed in the work class, and the D cylinder diameter is independent of the compressor operating speed, but the cylinder diameter.

plant. Quality, off.

In the upper section. The pressure excitation of the first and the segment has the greatest influence on the noise because of the gas shear that is excited by it. Cut and play. The connecting rod, the crankshaft and the body element, the intrinsic butterfly + is in the middle. Shangke Duan Fan Ge. Thereby the resonance is caused by the drill. This vibration is induced by the sputum. 1. It is in line with the sensitive human cheek Weifan, so the six sound levels are higher.

2 The squeaking of the air valve follows the opening and closing of the helium valve, so that the gas flooding at the valve passage changes, causing the gas and solid sound at the valve. The exhaust valve noise is known by the 苓 部 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , The attack valve seat, so in one, two stations are generated during the period. The shock sonar string and the lift limiter structure system generated when opening are also met. The cap of the capping system has Ai. The 激发 激发 激发 为 为 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡 坡揸 速度 速度 speed training flashing table. The masking speed is the angular velocity of the crankshaft.

Therefore, the Lulu valve lifts. As the speed increases, the punch and noise will also increase. Usually, the noise of the valve seat is large, especially when the valve is delayed. The masking speed of the valve closing moment is very large, so it produces a louder sound.

2 vortex noise! The high-speed airflow passes through the air passage, generating a large amount of mail, thereby forming a wide-band continuous. , the sound of the gas snoring, its large taste value é’º string is d vertical airflow direction of the sputum, degree, u valve valve speed, general mechanical metallurgy mine general mechanical air compressor noise control like sound absorption sound insulation And methods and measures for vocalization. Sound absorption means that when sound waves are incident on the surface of an object, part of the sound energy is absorbed by the object and converted into other forms of energy to reduce noise. Sound insulation is to close the noise source, control the noise in a small space, and block the propagation of sound. Silencing is to fix the porous material in the inner wall of the airflow passage in a fixed manner to achieve the purpose of weakening aerodynamic noise.

According to the characteristics of the noise source frequency, the noise control requirements and the site conditions, the following measures were taken for the noise control of each part of the air compressor.

The air intake noise control controls the intake noise of the air compressor, and a method of installing the muffler is adopted. Because the noise of the air inlet of the air compressor is low frequency, the peak appears in 31.563, such as 125 frequency bands, 200 sound energy accounts for 9899, ​​200 or more, only 12,630 or more, and the high frequency noise only accounts for 2 of the total sound energy. . According to the frequency analysis measured by the inlet noise, a resistant muffler is used. Its muffling performance is a wide frequency band of low frequency and low intermediate frequency, which is mainly suitable for reducing low frequency and low intermediate frequency noise. In order to ensure the muffling effect of the muffler, the intake muffler adopts a resistant muffler such as a fiber-free and non-foaming plastic material, that is, a composite micro-perforated plate muffler or a micro-perforated plate muffler. A resistive muffler that does not use a loose material such as fiber or foam is because the fiber material causes the fiber to escape, the foam plastic ages into a powder, and the escaping fiber or powder material enters the cylinder of the air compressor, causing the cylinder to be pulled, the machine A fault has occurred and it is not working properly.

Exhaust port noise control The air compressor with high exhaust pressure and high flow rate has high exhaust noise. In the exhaust system, a special muffler is required to enter the hall. The exhaust muffler requires a large amount of muffling, a wide muffling frequency band, a decompression expansion, and a reduction in the pressure drop of the exhaust vent to reduce the exhaust noise. For the ZW0.057 air compressor with low flow, the noise is not large and mainly for medium and high frequency, and a resistive muffler is used. The advantage of the resistive muffler is that it can silence the sound in a wide range of medium and high frequencies, especially for high frequency sound waves. Resistive muffler is a muffler that utilizes different structural forms of porous sound absorbing materials in the airflow pipe. It is often called a resistive material to absorb sound energy and reduce noise. It is the most widely used muffler in various types of muffler, and has a wide range of mufflers. The muffling frequency range is particularly significant in the mid-high frequency range. The sound waves enter the muffler, and most of the sound energy is absorbed, which acts as a muffler.

The body noise control controls the noise of the air noise of the air compressor. Considering the sound insulation and sound absorption control technology, the air compressor is added with an acoustic enclosure to prevent the noise from spreading. This is because radiated noise and electromechanical noise cannot be controlled by silence only. The normal air compressor has a lot of noise due to the lack of a sound enclosure, and the market is therefore greatly limited.

The minimum occupied space, the sound insulation cover is designed as a box with a size of 600, 1X450mmX0mm, considering the ventilation cooling and the installation of the air outlet at the operating port. The perimeter and the upper cover are designed with a detachable door panel for easy maintenance. 6. The door panel and the main frame are bolted together and sealed at the joint.

1.5. Elimination 2.4. Air inlet 3. Air compressor 1. Motor 1 main unit 3, force refers to 4. Pressing silver 5. Reporting gas 6. 绶 冲, 7. Plant mouth sound insulation cover wall material selection and sound insulation The entire soundproof enclosure is made of 2, thick steel plate material with sufficient sound insulation. All the skeletons are made of thin-walled square steel and thin-walled steel. In order to avoid the formation of sound insulation and low porosity caused by the resonance and the anastomosis of the thin steel under the action of sound waves, the sound insulation performance is reduced, and the damping layer asbestos asphalt is coated with a large internal friction in the cover except for the bolting and hanging connection according to the structure. The lacquer has a thickness of 6 to suppress the bending vibration of the steel sheet and reduce the sound radiation of the steel sheet cover.

The sound absorbing material on the inner surface of the sound insulation cover is selected from the inner surface of the sound insulation cover, and has better sound absorption performance. That is, the sound absorption coefficient of the person.

The value should not be low. 5. To this end, the sound absorption inside our painful sound is based on the ultra-fine glass wool with an average suction coefficient of 72, jNo¢ is 5Cm, only the density is 25kg. Slope, cotton A perforated steel plate with a glass cloth and a mouth perforation rate of 25 was used for the protection of Shanghai. ,Time.迮 琥 琥 棉 , , , , , , 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥 琥Beep, a small channel or gap can send a lot of noise. The test sonar will drop 2,253,0, the seam processing is very important, the hole, the treatment method such as 1 1 contamination, the treatment of the exhaust hole, etc.忖 to hold 8 materials. The hair is soaked in sound, such as the cabinet 8, 1 such a structure is not only the sound of the sound, the use of suction to reduce the creaking sound.

2 Ventilation and heat dissipation hole processing The air compressor will generate thermal energy of the anvil during operation. It must be thermally expanded to keep the crucible running normally. The sound insulation should not exceed 4, so the forced heat system must be used to ensure Enough ventilation. The sound of the well, the air on the bottom of the right two sides is set to enter the cold air after the air is forced to silence, and then the machine is rushed to the machine. The hot air is installed in the partition, the top axial fan is pumped to the exhaust and the channel is removed, and the control of the 3 body vibration control must be tempered; the vibration of the empty machine is mainly passed. Can 5! And the tube is passed outwards. The control of vibration is mainly to take the vibration isolation control, mainly adopting the wide-ranging 1; 嗝振栉, in the air pressure 叽 main 叽 and the child support plus vibration isolators, so that they call the formation of elastic 5 smile. The vibration is achieved with a small amplitude, which is the key link along the vibration isolation. 1 Add a vibration isolator between the main support and the motor's overall support. To reduce the vibration transmission to low, the sound control effect, the quality of the 4 directly with the control of the sound level of the same measuring point before and after the control, clothing, according to the formula, take the noise boat control after the same point welding Sound pressure level.

According to the data, the noise reduction can be reduced by 20 48. The left-hearted squatting can be regarded as the control of the efficacies, and the measures are passed. Beep 4, the vibration will be 2, 0.057 so that the noise of the sail is reduced from the original 79.5 to 6.2, which is reduced by 8.348, and the control beam is not bad. Both meet the requirements of the user. Also increase the market for a wide range of products, the overall effect reached a wide-ranging period, 1 post forever. Volumetric Compression Technical Manual啪. Beijing Machine Industry Press, 2000.

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