KR100392426B1 - Ducted noise absorptive noise damper - Google Patents

Abstract

The present invention relates to a sound-absorbing noise attenuation device for ducts, in particular, the diameter of the hole (23) perforated in the flat portion 22 of the splitter (2) installed in the vertical direction at a predetermined interval inside the duct body (1) Is set within 2mm-5mm, the spacing of the holes 23 is such that the ratio of the open area to the total area of the plate to be drilled is 16% -33%, and the thickness of the punched plate is optionally set between 0.6mm-0.8mm. However, the sound absorbing material 25 filled in the splitter 2 uses glass fibers having a specific gravity of 12 kg / m 3 to 30 kg / m 3 to compensate for the disadvantages of the conventional passive silencers having low sound absorbing performance in the low frequency band. Through this method, high attenuation performance can be achieved even in the low frequency band of 1/1 center frequency band 63Hz to 250Hz, which can greatly improve the attenuation efficiency of noise and greatly improve the reliability of the silencer response performance. It is to be hurt.

Description

Ducted noise absorptive noise damper

The present invention relates to a sound-absorbing noise attenuation device for ducts, and more particularly, to compensate for the disadvantages of conventional passive silencers, which have low attenuation performance in the low frequency band, even in the low frequency band from 1/1 to 63 Hz to 250 Hz. It is invented so that high sound performance can be exhibited.

In other words, the present invention is a silencer invented mainly to reduce or control noises transmitted through air and gas ducts for cooling and heating air conditioning and ventilation systems and various industrial facilities. The present invention relates to a sound absorbing noise attenuation device for ducts invented to obtain an acoustically much satisfactory attenuation effect in a wide range of frequency bands.

Existing mufflers use foamed sound-absorbing materials, such as glass fibers or rock wool, or foams such as sponges and polyurethanes, which are mostly porous sound absorbing materials composed of continuous bubbles.

The common problem of the existing sound absorbing materials is that the sound absorption in the low frequency band is low and the sound in the low frequency band with long sound wavelengths ranging from 1/1 Hz frequency band 63Hz to 250Hz has a very small attenuation, which makes it difficult to expect attenuation effects. It has been the level of technology in the industry and its biggest challenge.

In particular, foamed sound-absorbing materials such as sponges and polyurethanes made of organic materials are used to generate extreme soot and toxic gases when they are fired, so that various problems have occurred. To solve these problems, glass fiber, which is a non-combustible material, is an inorganic material. By using, we have developed a technology that can achieve acoustically high sound attenuation effect even in low frequency band.

On the other hand, according to Korean Utility Model Publication No. 90-807 (name: sound absorbing body for duct silencer), the sound absorbing body having a plurality of sound absorbing holes on both sides with arbitrary thickness in the duct body which opened the front and rear as needed. In the sound absorbing body of the duct silencer which maintains the space | interval part mutually, WHEREIN: It is the structure which provided the corrugated glass fiber in the sound absorbing both sides direction in the center of a sound absorbing body, and installed the synthetic resin film and the glass cloth on both sides of the glass fiber in steps. .

However, in such a sound absorbing body, the noise is reflected by the synthetic resin film by using the synthetic resin film, and there is a problem in that the attenuation efficiency is very low.

The present invention has been made in order to solve such a conventional problem, the diameter of the hole to be punctured within the predetermined diameter in the flat portion of the splitter installed in the vertical direction at a predetermined interval in the interior of the duct body within the predetermined diameter Is set within a certain percentage of the open area ratio to the total area of the plate to be drilled, and the thickness of the perforated plate is selected between the predetermined thicknesses to compensate for the shortcomings of the conventional passive silencers having low attenuation performance in the low frequency band. The present invention provides a sound absorbing noise reduction device for a duct that can exhibit high acoustic performance even in a low frequency band from 250 Hz, that is, an acoustically more satisfactory attenuation effect can be obtained in a wide range of frequencies from a low frequency band to a high frequency band.

An object of the present invention described above, the body having a rectangular enclosure form that both sides are open so that it can be connected to a common duct; Both ends of the plate having the same height as the sidewall height of the body are formed with a curved portion having a quarter or quarter ellipse or semi-circle or semi-ellipse, and a plurality of flat portions having a predetermined diameter are formed in the planar portion formed between the two curved portions. A plurality of splitters having a configuration in which holes are drilled at regular intervals and installed at predetermined intervals within the body to allow sound and fluid to pass through a passage formed between the planar portions facing each other; In the sound absorbing silencer for the duct composed of a sound absorbing material is filled in the inside of the splitter so that the flow resistance is low, the sound energy dissipation effect is very high and the sound energy is easily penetrated, the hole of the hole drilled in the flat portion of the splitter The diameter should be within 2mm-5mm, and the gap of the hole can be achieved by setting the ratio of open area to 16% -33% of the total area of the plate to be perforated, and the thickness of the perforated plate set between 0.6mm-0.8mm.

Therefore, it is possible to significantly attenuate acoustically in a wide range of frequencies from the low frequency band to the high frequency band.

1 is a perspective view of a silencer according to the present invention.

Figure 2 is a plan sectional view of the silencer in which the present invention is carried out.

3 is a plan sectional view of yet another silencer in which the present invention is practiced.

Figure 4 is an enlarged cross-sectional view showing the main part of the silencer in which the present invention is implemented, the splitter is fixedly installed on the body.

5 to 7 is a graph showing the sound absorption performance according to the cross-sectional ratio of the length of the silencer.

8 and 9 are graphs showing the effect of the glass fiber woven fabric by the length of the silencer on the sound insulation performance.

10 and 11 are graphs showing the effect of the perforation rate of the silencer on the sound insulation performance.

Explanation of symbols on the main parts of the drawings

1: body 2: splitter

3: passage 4: fixing piece

21: curved portion 22: flat portion

23: hole 24: glass fiber fabric

25: sound absorbing material 26: ":" type hook 26

41: "∩" type hook

Hereinafter, a configuration according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows a perspective view of a silencer according to the present invention, Figure 2 shows a flat sectional view of a silencer according to the present invention, Figure 3 shows a flat sectional view of another silencer according to the present invention, Figure 4 shows an enlarged cross-sectional view of the main portion showing a form in which the splitter is fixedly installed on the body of the silencer according to the present invention.

In addition, Figures 5 to 7 are graphs showing the sound insulation performance according to the cross-sectional ratio of the length of the silencer, Figures 8 and 9 are graphs showing the effect of the glass fiber fabric by the length of the silencer on the sound insulation performance 10 and 11 are graphs showing the effect of the perforation rate of the silencer on the sound insulation performance.

According to this, the body (1) having a rectangular housing shape with both sides open so as to connect and install a common duct; Both ends of the plate having the same height as the sidewall of the body 1 are formed with a curved portion 21 having a quarter shape or a quarter ellipse shape or a semicircle shape or a semi-ellipse shape, and is formed between the two curved portions 21. The plane portion 22 has a configuration in which a plurality of holes 23 having a predetermined diameter are drilled at regular intervals, and sound and fluid can pass through the passages 3 formed between the plane portions 22 facing each other. Several splitters (2) installed at predetermined intervals in the body (1) so as to be provided;

In the sound absorbing silencer for the duct composed of a sound absorbing material 25 is filled in the inside of the splitter 2 so that the flow resistance is low, the sound energy dissipation effect is very high and the sound energy can easily penetrate,

The diameter of the hole 23 drilled in the flat part 22 of the splitter 2 is set within 2 mm-5 mm, and the gap of the hole 23 is 16% of the open area ratio to the total area of the plate to be drilled. To be -33%, the thickness of the perforated plate is selectively set between 0.6mm-0.8mm, glass fiber having a specific gravity of 12kg / ㎥ to 30kg / ㎥ as the sound absorbing material 25 is filled in the splitter (2) In addition, one or more splitters 2 having the above-described configurations may be additionally installed inside the body 1 to provide another one or more between the flat portions 22 of the respective splitters 2. Characterized in that the passage (3) is provided.

In addition, the device of the present invention spot-fixes the fixing piece (4) in which the "∩" -type locking ring 41 is integrally molded on both inner side ends of the body (1), On the end, it is characterized in that the "∪" -type locking ring 26 that can be fitted in the slide manner to the "걸림" -type locking ring 41 of the fixing piece 4 integrally molded.

Referring to the operation and effect of the device of the present invention configured as described above are as follows.

First, the sound energy enters the porous sound-absorbing material in the splitter 2 of the muffler, and if a large amount of sound energy in the sound absorbing material 25 is dissipated before re-entering the passage, a large amount of sound energy is absorbed even at a wide bandwidth. Can be effectively attenuated.

The sound absorbing material can be satisfied if the height of the passage 3 is small compared to the wavelength (ie 2 h / λ) and the porous sound absorbing material is sufficiently open so that the sound energy can be incident well into the splitters rather than being reflected at the interface. .

This requires a "fluffy" material of low flow resistance and is satisfied by the use of porous sound absorbing materials with moderate flow resistance.

In other words, in order to make sound energy easily penetrate the sound absorbing surface and dissipate well, the splitter should be thick and filled with porous sound absorbing material with low flow resistance.

Therefore, when determining the thickness of the splitters and the flow resistance of the sound-absorbing material, it is necessary to select a tradeoff between balance and balance.

In general, the kinematic structure of the muffler is determined by the target noise attenuation capacity and the shape of the frequency curve. In order to obtain an appropriate noise attenuation capacity, the thickness of the splitter 2d should be about 1/8 of the wavelength and the height of the passage. (2h) must be shorter than the length of the wavelength so that noise can be attenuated properly.

In order to allow adequate noise absorption and dissipate to the required level, the flow resistance (R₁d) of the 2d thick splitter must be two to six times the intrinsic impedance of the gas in the silencer passage.

The noise attenuation capacity of the muffler can be maximized by maximizing the value of (P / A) L _h as it is proportional to the ratio of perimeter and area, P / A, length ℓ and L _h .

On the other hand, it can be seen that the amount of noise attenuation and the width of the attenuated frequency band change according to various open space ratios in the cross section of the silencer.

Experimental results of noise attenuation and attenuated frequency bands when the silencer cross sections (h / ω) are 30%, 40%, 48%, and 53%, respectively, are shown for each silencer length in FIGS. Therefore, it can be seen that as the opening ratio decreases, the amount of noise attenuation gradually increases, and the attenuated frequency bandwidth gradually widens.

In addition, another factor that plays a crucial role in determining the amount of noise attenuation and the width of the frequency band to be attenuated is the amount of attenuation and the width of the frequency band to be attenuated, depending on the choice of finish material on the sound absorbing material surface of the splitter and the method of mounting the finish. There is a huge change.

Many silencer manufacturers still use glass fiber as the sound-absorbing material that is nonflammable and has the highest sound absorption in the medium and high frequency bands and the lowest price.

However, the wrong material selection and the method of use of the fiberglass cloth, which is used for the purpose of preventing the scattering of the glass fiber caused by the flow of fluid such as air or gas, are not considered at all acoustically. The damping effect is very poor, causing the production cost to increase due to excessive use of the sound absorbing material, which results in only increasing the manufacturing cost of the silencer.

To be more specific, many muffler makers have selected a very dense and thick glass fiber woven fabric for the purpose of preventing glass fiber from scattering when acquiring glass fiber as a sound absorbing material without any acoustic consideration. In order to make it easier to use, the glass fiber fabric is produced and sold in a state in which the glass fiber is attached with a polyethylene film in the process just before it is shipped from a glass fiber manufacturing company. It is very difficult to expect sound absorbing performance because the sound energy is not reflected at the interface of the sound absorbing material due to the glass fiber woven fabric of thick and neglected structure and the polyethylene film which is the adhesive material. .

8 and 9 are noise attenuation of a silencer using a glass fiber bonded to a glass fiber woven fabric with polyethylene and a silencer using a glass fiber using a glass fiber woven fabric considered to be acoustically absorbed sound energy. The experimental results are compared with the attenuated frequency bandwidth.

In addition, another important factor that determines the amount of noise attenuation and the width of the frequency band to be attenuated depends on the geometry of the perforated plate, the perforation rate (%), the diameter of the perforated hole (mm) and the thickness of the perforated plate (t). .

FIG. 10 and FIG. 11 show the results of a comparative experiment of the amount of noise attenuation that varies according to the puncturing rate (%) and the width of the attenuated frequency band.

In addition, the factor that can determine the amount of other noise attenuation depends on the length (l) of the silencer, Figures 5 to 7 shows the results of comparing the noise attenuation varying with the length of the silencer and the width of the frequency band to be attenuated.

On the other hand, the silencer is composed of a body 1 and a splitter (2) of the rectangular box-shaped open on both sides so as to connect and install the duct.

At this time, the body (1) may use a molten zinc steel sheet, stainless steel sheet, or other materials such as PVC, the splitter (2) inside the silencer is a quarter or quarter ellipse type that is not perforated in the tip and end In the semi-circular or semi-elliptic shape, the plates having the curved surface portions 21 are formed to face each other, and the flat portions 22 facing each other at the center thereof are made of perforated plates, and the sound energy passing through the passages 3 is perforated plates. Sound energy is dissipated while penetrating the glass fiber cloth 24 positioned on the rear surface of the perforated plate through the hole 23 of the flat part 22 and entering the sound absorbing material 25 which is glass fiber.

The properties of the perforated plate, i.e., the flat part 22, are represented by the diameter and spacing of the perforated holes 23 and the thickness t of the perforated plate, in particular the weave and mounting conditions of the glass fiber woven fabric 24 on the back side, and sound absorbing material. Depending on the flow resistance of (25), the characteristics make a lot of difference.

It is advantageous to select a small diameter for the size of the hole 23 drilled in the flat part 22, and it is suitable to be between about 2 mm and 5 mm, and the space of the hole 23 is compared to the total area of the plate to be drilled. It is advantageous to have the ratio in the range of 16% to 33%, and the thickness of the perforated plate is preferably between 0.6mm and 0.8mm.

In addition, when the sound absorbing material 25 is used as a glass fiber, the glass fiber woven fabric 24 used to prevent the scattering of the glass fiber due to fluid such as air or gas is acoustically sound sound interface, that is, glass It is advantageous that the tissue state is not dense without the thickness of the fiberglass woven fabric so as to be able to enter the surface of the fiber well.

In addition, the selection of the sound absorbing material 25 to be used in the filling form is advantageously low in specific gravity to a fluffy degree with low flow resistance.

Porous material composed of continuous bubbles with good dissipation and good dissipation of sound energy is most effective, and specific gravity selection of sound absorbing material is advantageous from 12kg / ㎥ to 30kg / ㎥.

In addition, one or more splitters 2 installed in the body 1 may be installed. When two or more splitters 2 are installed, the splitters 2 may be disposed between the planar portions 22 of each splitter 2. One passage 3 is formed.

On the other hand, as a means for fixedly installing the splitter 2 of the silencer to the body 1 as shown in Fig. 4 "단부" -type locking ring 41 is integrally formed on both inner side ends of the body (1) The machined fixing piece 4 is fixedly installed by spot welding, and the " ∪ " type locking ring 26 is integrally formed on the end of the splitter 2, thereby forming the splitter 2 in the body. In the case of fixed installation in (1), the "∪" -type locking ring (26) of the splitter 2 is coupled to the "형" -type locking ring (41) of the fixing piece (4) by a slide method It can be easily fixed and installed.

As described above, according to the present invention, the diameter of the hole to be drilled in the flat portion of the splitter installed in the vertical direction at a predetermined interval in the duct body within a predetermined diameter, but the interval of the hole is the total area of the plate to be drilled By setting the ratio of the open area ratio to a certain percentage and setting the thickness of the perforated plate by selecting between the predetermined thicknesses, it compensates for the shortcomings of the existing passive silencers with low sound absorption performance in the low frequency band. It is a very useful invention that can exhibit a high attenuation performance even in the low frequency band up to significantly improve the attenuation efficiency of the noise, as well as significantly improve the reliability of the silencer response performance.

Claims (4)

A body (1) having a rectangular housing shape in which both sides are open so as to be connected to a general duct; Both ends of the plate having the same height as the sidewall of the body 1 are formed with a curved portion 21 having a quarter shape or a quarter ellipse shape or a semicircle shape or a semi-ellipse shape, and is formed between the two curved portions 21. The plane portion 22 has a configuration in which a plurality of holes 23 having a predetermined diameter are drilled at regular intervals, and sound and fluid can pass through the passages 3 formed between the plane portions 22 facing each other. Several splitters (2) installed at predetermined intervals in the body (1) so as to be provided; In the sound absorbing silencer for the duct composed of a sound absorbing material 25 is filled in the inside of the splitter 2 so that the flow resistance is low, the sound energy dissipation effect is very high and the sound energy can easily penetrate, The diameter of the hole 23 to be drilled in the flat portion 22 of the splitter 2 is set within 2 mm-5 mm, and the interval of the hole 23 is 16% − of the open area ratio to the total area of the plate to be drilled. 33%, the thickness of the perforated plate is optionally set between 0.6mm-0.8mm, Sound absorbing material 25 is filled in the splitter (2) is a sound absorption type noise damping device for ducts, characterized in that the specific gravity is 12kg / ㎥ to 30kg / ㎥ glass fiber. delete delete The method according to claim 1, On both inner side end portions of the body 1, a fixing piece 4 formed by integrally forming a "∩" shaped hook ring 41 is fixedly fixed by spot welding, and on the end of the splitter 2, Sound absorbing type noise attenuation device for ducts, characterized in that the integrally formed and processed "∪" -type locking ring 26 that can be hooked into the "∩" -type locking ring (41) of the fixing piece (4).