JP3031450U - Silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] A low-frequency sound generated from a fan or motor in a duct, which is placed in the middle of a duct that guides the flow of air and is difficult to muff by absorbing even with a muffling material, is silenced. Provided is a muffling device. [Composition] A silencer 10 provided in the middle of a duct for guiding the flow of air and having two openings in the direction of noise propagation.
The silencer 10 comprises a hollow cylindrical body 12, a partition plate 26 for branching the propagation of noise in the propagation direction is provided inside the cylindrical body 12, and a sound absorbing material is provided on the inner wall of the cylindrical body 12. 20 is provided, the inner wall of the hollow cylindrical body has an enlarged surface 22 that gradually expands continuously from the noise propagation inlet side opening to the middle of the noise propagation direction, and the noise propagation outlet continuously from the middle position. It is provided with an expansion / contraction surface 24 that is gradually expanded / contracted to the side opening.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

 The present invention relates to a muffler which is arranged at an intermediate position of a pipe such as an air conditioning duct and reduces noise in a duct including a fan, a motor and the like.

[0002]

[Prior art]

 Conventionally, in order to perform air conditioning in buildings and other structures, air ducts have been piped inside and around the buildings, and air is circulated through the ducts by blowers and the like. At that time, some measures have been taken to remove as much as possible the noise generated by the blower fan installed at the entrance and exit of the duct and its motor, and the noise that the air flows. As one of them, bend pipes such as ducts into a U-shape such as a muffling elbow using a space not used by humans such as in the ceiling, between walls of buildings, or between floors. By installing the sound wave on the wall of the duct to absorb it, the amount of sound transmitted is reduced, and the sound is suppressed by preventing it from directly reaching the interior of the building. In addition, it has been applied to the inside of the duct piping itself to muffle the sound.

However, in order to bend and install pipes such as ducts in a U-shape in a space which is not used by humans, such as between walls of a building or between floors, it is necessary to do so. Space is required. Therefore, in a relatively small-scale building, in order to secure more space for human use, the space between the walls and between the floor and the ceiling is inevitably limited, so pipes should be installed. It becomes difficult to muffle the sound by bending it.

Further, regarding the sound deadening when the sound deadening material is provided inside the duct, a relatively high frequency portion of noise generated from the fan or the motor of the duct can be absorbed by the sound absorbing material. It is difficult to absorb low-frequency noise, and as shown in Fig. 8, secondary noise is generated due to fluid fluctuations caused by entering the equipment from the air inlet and rapidly expanding the internal space from the duct. There was a problem of causing it.

The present invention has been made in view of the above-mentioned conventional problems, and one of the objects thereof is to bend and install ducts by silencing sound without bending and installing duct pipes. A large amount of space for human use will be secured by reducing the required space between the ceiling and floor and between walls. In addition, since the duct is not bent, the resistance is low and the shaft power is low, so the generated noise can be suppressed. Another object of the present invention is to reduce the cost of the duct by eliminating the length of the pipe required to bend and install the duct pipe, and it is difficult to muffle the sound by absorbing it with a muffling material. It is an object of the present invention to provide a muffling device that muffles low-frequency sound generated from a motor or a motor.

[0006]

[Means for solving problems]

 In order to achieve the above object, in the device according to the first aspect of the present invention, there is provided a muffling device 10 that is provided in the middle of a duct or the like when guiding the flow of air and has two openings 14 in the noise propagation direction. The silencer 10 comprises a hollow cylindrical body 12, a partition plate 26 for branching the propagation of noise in the propagation direction is provided inside the cylindrical body 12, and the sound absorbing material 20 is provided on the inner wall of the cylindrical body. The inner wall of the hollow cylindrical body 12 has an enlarged surface 22 that gradually expands from the noise propagation inlet side opening 14 to the middle of the noise propagation direction, and the noise of the noise is continuously generated from the middle position. It is configured to include a scaling surface 24 that gradually expands and contracts to the propagation exit side opening 14.

According to the second aspect of the present invention, the branch portion between the expansion surface 22 and the expansion / contraction surface 24, which is a midway position in the noise propagation direction, may be located at a substantially central position in the noise propagation direction.

In the invention according to claim 3, the partition plate 26 may be set to be shorter than the entire length of the hollow cylindrical body 12.

According to a fourth aspect of the present invention, the partition wall plate 26 extends from one of the openings 14 toward the other opening 14 to a midway position on one plane along the noise propagation direction. Good.

In the invention according to claim 5, the partition plate 26 may extend from any one of the openings 14 to a substantially central position of the entire length of the hollow cylindrical body.

[0011]

[Embodiment of device]

 The present invention is a silencer provided in the middle of a duct for guiding the flow of air and having two openings in the direction of noise propagation, which silencer comprises a hollow cylindrical body. A partition plate for branching the propagation of noise in the propagation direction is provided inside, and a sound absorbing material is provided on the inner wall of the same cylinder, and the inner wall of the hollow cylinder continues from the noise propagation inlet side opening. The silencer has an enlarged surface that gradually expands to the middle of the noise propagation direction, and also has an expansion and contraction surface that gradually expands and contracts from the middle position to the noise propagation outlet side opening. Therefore, it has an enlarged surface and an expanded / contracted surface that are continuously formed inside the cylinder at the noise propagation inlet side opening and the noise outlet side opening. As a result of no expanded or expanded stepped portion, the sound absorbing material stretched inside sufficiently absorbs the noise generated by the air flowing into the inside of the cylinder, while preventing turbulent air flow and increasing the generated noise amount itself. Can be suppressed. At the same time, by providing the partition plate in the cylinder, the partition plate more effectively exerts the sound deadening effect by dividing the sound. Furthermore, since the sound is smoothly expanded by this expansion surface, more sound is applied to the sound absorbing material on the expansion / contraction surface side, and the sound absorbed by the sound absorbing material on the expansion / contraction surface side can be increased. Together with making it easier to cause a lot of sound interference at the exit due to the branching of, the sound deadening effect is greatly maintained synergistically. Therefore, a sufficient noise reduction effect can be obtained without bending and installing the duct pipe for noise reduction, and it is not necessary to secure a large space for manipulating the pipe, and the length of the duct can be shortened. Also, even if the duct is installed without bending, a sufficient noise reduction effect can be obtained, so there is no need to secure a space for storing the bent portion of the duct, and a wide space for humans such as buildings is secured. I can get things done. In addition, the cost of the duct itself can be reduced by shortening the duct piping. Also, since it is not necessary to bend and install the pipes for noise reduction, the power load of the air supply fan and the motor can be small, and the amount of electricity required for them can be reduced, thus saving the electricity bill. be able to. In addition, the sound absorbing material that forms the expansion surface and the expansion and contraction surface provided in the hollow cylindrical body has a heat insulating effect, so that it suppresses not only noise but also heat transfer in the air, so that air is passed through the duct. Even if it is made to flow, the temperature inside the building can be kept constant.

Further, in claim 2, since the branching portion between the expansion surface and the expansion / contraction surface, which is a midway position in the noise propagation direction, is substantially at the center position in the noise propagation direction, the sound absorbing material on the expansion surface side absorbs the sound. At the same time, sound absorption by the sound absorbing material on the expansion / contraction surface side and sound interference due to reflection occur most, and the sound deadening effect of the sound deadening device can be maximized. In addition, the resistance to air flow is minimized, which contributes to the reduction of electricity costs by downsizing the fan and motor in the duct.

In the third aspect, the partition plate is set shorter than the entire length of the hollow cylindrical body. The partition plate can separate the sound transmitted in the direction of the air flow into two, and at the same time, can act so that the sound is easily absorbed and reflected inside the cylinder. Therefore, each of the two separated sounds interferes with each other after passing through the partition plate, which significantly improves the silencing effect. Further, the partition plate has a greater effect of silencing by thickening a member made of the same material as the material forming the hollow cylinder.

Further, in the present invention, the partition plate is extended from one of the openings toward the other halfway position on one plane along the propagation direction, so that the partition plate is exposed to air. While separating one sound that is transmitted in the flow direction into two, the sound is absorbed inside the cylinder, and the separated sound causes interference after passing through the bulkhead plate, greatly reducing the sound deadening effect. Improve to. The muffling can be performed more effectively by providing a plurality of partition plates in the hollow portion of the hollow cylindrical body. Further, if the partition plate is made of a member made of the same material as the material forming the hollow cylindrical body, or particularly a sound absorbing material, the sound deadening effect is further enhanced.

Further, in the present invention, the partition plate extends from any one of the openings to a substantially central position of the entire length of the hollow cylindrical body, so that the device can be easily manufactured specifically. In addition to enabling mass production and low cost, it is easy to measure the volume of sound that corresponds to the size of the opening and the entire length of the cylinder, making it easy to standardize the volume of sound that corresponds to the size. Be seen. Furthermore, the interference with the sound transmission of the partition plate and the interference with the sound reflected without being absorbed by the sound absorbing material on the expansion / contraction surface side are the best conditions to maximize the sound deadening effect. Also, when the partition plate is installed from the midway position of the noise propagation direction toward the outlet side of the noise propagation direction, the sound that enters the hollow part of the hollow cylinder from the opening of the noise propagation inlet side expands. It is enlarged once by the face. Then, it is sharply reduced by the expansion / contraction surface, and at the same time, it is branched into two by the partition wall provided in the hollow portion of the hollow cylindrical body, so that the silencing effect due to the reduction is enhanced.

[0016]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. 1 to 6 show an embodiment of a muffler 10 according to the present invention. The muffler 10 of this embodiment is installed at an intermediate position of a duct to provide smooth air guidance and noise in the duct. It is a muffling device 10 for the purpose of erasing.

In FIG. 1, a muffling device 10 according to the embodiment is a hollow rectangular cylindrical body 12 made of metal having a length A, a width B, and a length C. On both sides of the hollow cylindrical body 12 in the direction of noise propagation, openings 14 are provided as noise inlets and outlets, respectively. As shown in FIG. It is formed in a substantially rectangular shape of b. At the same time, as shown in FIG. 3, the openings 14 are provided in the central portions of both side surfaces of the hollow cylindrical body 12, and the peripheral portions of these openings 14 are joined as connection margins for connecting to a duct. A section 16 is provided.

As described above, the hollow cylindrical body 12 has a substantially rectangular parallelepiped shape and each opening 14 has a substantially rectangular shape, so that the silencer 10 itself can be manufactured very easily. Therefore, since it is not necessary to process a complicated shape, it is possible to carry out the manufacturing by a very simple process, and it is possible to mass-produce it at low cost and in a short time.

The hollow cylindrical body 12 has a hollow portion 18 through which air and noise can flow. As shown in FIGS. 2 and 5, the hollow cylindrical body 12 is formed in a flat plate shape on the left and right sides in the noise propagation direction, with a heat insulating and silencing material such as glass wool attached inside. Further, as shown in FIGS. 2 and 4, the upper and lower parts of the inside are formed so as to gradually expand from the noise propagation inlet side opening 14a to a midway position in the noise transmission direction of the hollow cylindrical body 12. In addition to the expanded surface 20, the expanded surface 24 is further expanded and contracted continuously from this midway position to the noise outlet side opening 14b.

That is, in FIGS. 2 and 4, the enlarged surfaces 22 are provided above and below the hollow portion 18 of the hollow cylindrical body 12, and the sound absorbing material 20 is stretched over the hollow portion 18 of the hollow cylindrical body 12. . In the embodiment, the enlarged surface 22 is formed as a slanted surface which is continuously enlarged in the vertical direction up to a substantially central position in the noise propagation direction of the hollow cylindrical body 12. Then, from the center position of the cylindrical body, which is the end of the enlarged surface 22, further continuously expands and contracts toward the opening 14b on the other end side in the noise propagation direction, and expands and contracts in a barrel-shaped cross section as a whole to the other end The aperture is reduced and converges to the other end aperture. The sound absorbing material 20 is stretched over the inner wall forming the expansion / contraction surface 24 as in the expansion surface. These sound absorbing materials 20 absorb the sound generated by the flow of air.

As described above, the space inside the cylindrical body 12 is not rapidly expanded or expanded from each opening, but the space is expanded continuously along the propagation direction of the noise of the hollow cylindrical body 12 continuously from the opening. In addition, since the noise is propagated through the opening and there is no sudden expansion of the space due to the step as soon as the noise propagates through the opening, the sound absorbing material 20 stretched inward while maintaining the natural outflow of air causes a hollow cylinder. It is possible to sufficiently suppress the noise generated in the hollow portion 18 of the body 12 and prevent the turbulent airflow from being generated, so that the secondary generated noise amount itself can be greatly suppressed.

The expanding surface 22 and the expanding / contracting surface 24 formed in the hollow portion 18 of the inner wall of the hollow cylindrical body 12 are not limited to the sound absorbing material 20 used in the present embodiment, but may be rock wool, cow wool felt, polystyrene foam. It may be a foam, a urea foam, a foam glass, or the like. Further, as shown in FIGS. 2 and 4, in the present embodiment, the branch portion between the expansion surface 22 and the expansion / contraction surface 24 is set at a substantially central position in the noise propagation direction. As a result, the sound absorbing material 20 on the enlarged surface 22 side absorbs the sound and the sound absorbing material 20 on the expanding / contracting surface 24 side causes the most sound absorption and sound interference, thereby enhancing the sound deadening effect.

On the other hand, as shown in FIGS. 2, 4 and 5, in the hollow portion 18 of the hollow cylindrical body 12, from the entrance side opening 14a for sound propagation to another opening 14b on one plane along the sound propagation direction. A partition plate 26 is stretched as a substantially rectangular long plate having a certain thickness toward the air flow substantially parallel to the air flow. That is, the partition plate 26 is set to be shorter than the entire length of the hollow cylindrical body 12.

As shown in FIGS. 3 and 6, in the embodiment, the partition wall plate 26 is provided at a substantially central position in the vertical direction of the hollow portion 18 of the hollow cylindrical body 12 and is provided in the horizontal direction. The opening 14a on the inlet side is divided approximately into two. The partition plate 26 is not limited to this embodiment, and may be provided in the vertical direction of the hollow portion 18 of the hollow cylindrical body 12 in the vertical direction. Further, the partition plate 26 may be attached so as to partition the hollow portion 18 of the hollow cylindrical body 12 in the vertical direction. Further, in the embodiment, the partition plate 26 extends from the sound transmission inlet side opening to a position approximately in the center of the entire length of the hollow cylindrical body 12. The partition plate 26 may be extended from any of the openings 14a and 14b to not only the substantially central position of the entire length of the hollow cylindrical body 12 but also other midway positions.

As described above, the partition plate 26 provided in the hollow portion 18 of the hollow cylindrical body 12 can more effectively exhibit the sound deadening effect. Further, by smoothly expanding the sound once by the expansion surface 22 described above, more sound hits the sound absorbing material 20 on the expansion / contraction surface 24 side, and sound absorbed by the sound absorbing material 20 on the expansion / compression surface 24 side and reflected sound are reflected. Since it is possible to increase the amount, it is easy to cause a lot of noise interference due to the shunting of air by the partition plate 26, and synergistically enhance the sound deadening effect.

The partition plate 26 may be set shorter than the entire length of the hollow cylindrical body 12 and longer than the central position of the hollow cylindrical body 12, or may be shorter than the central position of the hollow cylindrical body 12 and in that case, an effect similar to that of this embodiment is obtained. You can get the fruit. In other words, the noise propagating in the direction of noise propagation is separated into a plurality of noises, and the noises separated by the partition plate 26 interfere with each other after they are merged with each other to produce a noise suppressing effect. Further, it also interferes with the sound reflected by the expansion / contraction surface 24 without being absorbed, thereby enhancing the sound deadening effect.

In particular, as shown in FIGS. 2 and 4, in the present embodiment, the midway position in the noise propagation direction is substantially the center position in the noise propagation direction, and the partition plate 26 is opened on the inlet side in the noise propagation direction. It is provided from the mouth 14 to a substantially central position in the noise propagation direction. Therefore, the noise propagating in the noise propagation direction by the partition plate 26 provided in the hollow cylindrical body 12 is separated into a plurality of noises from the position of the transmission inlet side opening 14, and each of the noises interferes by the partition plate 26. Will be caused.

The separated sound causes interference after merging, and further interferes with the sound reflected without being absorbed by the expansion / contraction surface 24 to further enhance the sound deadening effect. Further, the partition plate 26 extends from any one of the openings 14 to a substantially central position, so that the device can be specifically manufactured easily, mass production and low cost manufacturing can be performed, and the size of the openings can be increased. The volume reduction corresponding to the entire length of the cylinder and the cylinder can be easily standardized.

Next, the operation of this embodiment will be described. The muffling device 10 according to the present embodiment is provided at an intermediate position of the pipe of the duct or the like, and effectively muffles sound. Noise generated from a sound source such as a blower fan flows in from the noise propagation inlet side opening 14a of the hollow cylindrical body 12 and is divided into hollow portions 18a and 18b which are vertically divided into two by a partition plate 26. . Then, the hollow cylindrical body 12 is guided to the substantially central position along the enlarged surface 22. The enlarged surfaces 22 are formed at two positions above and below the hollow portion 18 of the hollow cylindrical body 12, and at the same time, the sound absorbing material 20 absorbs sound and silences it.

The noise is located at the center of the hollow portion 18 and proceeds from the enlarged surface 22 along the expansion / contraction surface 24 that is expanded / contracted toward the noise propagation outlet side opening 14b, and further to the inner wall side during this time. Sound is absorbed by the stretched sound absorbing material 20. The flow and sound merge from the middle position, which is the central position inside the cylinder, to the further downstream side, and while interfering with each other, the sound deadening effect is synergistically synonymously effected for sound deadening.

When the silencer according to the present invention is used at an intermediate position of the duct 28 as shown in FIG. 7C, for example, as shown in FIGS. Conventionally, the silencer 30 is required for the four elbows of the bent portion to suppress the primary noise, but the silencer according to the present invention is provided at the middle position of the duct 28 as shown in FIG. 7C. It has been confirmed that a single silencing device 10 can be used to produce silencing effects corresponding to these. As shown in the operation and experimental data described below, a single member has a greater effect of silencing than conventionally using a plurality of members for silencing.

The following is a comparison of experimental example results and theoretical attenuation of the silencer according to the present invention. The size of the silencer is 2000 mm × 1100 mm × 1400 mm when viewed from the opening side. The size of the duct or opening is 1000 mm × 1000 mm in the vertical and horizontal directions. The size of both silencers was the same. The silencer is lined with GW 40K and 50t glass wool. The attenuation amount calculation formula is 10 LogS × α / A. (S: GW lined area (12.4 square meters), A: duct cross-sectional area (1 square meter), α: sound absorption coefficient of GW) Frequency experimental value attenuation amount theoretical attenuation amount sound absorption coefficient α 63 Hz − 7 [dB] -0.5 [dB] 0.09 125Hz -10 [dB] -3.5 [dB] 0.18 250Hz -12 [dB] -5.4 [dB] 0.28 500Hz -17 [ The measured attenuation amount of dB] -10.0 [dB] 0.8 was obtained.

In the muffler according to the present invention, the air flowing in from the opening smoothly flows without causing turbulence, so that the air can be effectively rectified. The present invention is not limited to the configuration of the embodiment described above, and any modification may be made without departing from the essence of the invention described in the scope of the utility model registration request. For example, in the embodiment, the expansion surface 22 and the expansion / contraction surface 24 are provided only on the upper and lower inner walls in the flow direction, but the expansion / contraction surface may be formed on the left and right sides as well. Rather, it is possible to obtain a more effective silencing effect. Further, the enlarged surface 22 and the expanded / contracted surface 24 are formed so that the inner wall of the hollow portion 18 forms a substantially circular shape, a pentagonal shape, a hexagonal shape, or another polygonal shape when the hollow cylindrical body 12 is longitudinally cross-sectioned. However, this case is also included in the scope of the present invention.

[0034]

[Effect of device]

 As described above, according to the muffler according to the first aspect of the present invention, the muffler is provided in the middle of the duct or the like when guiding the flow of air, and has two openings in the noise propagation direction. The silencer is made of a hollow cylinder, and a partition plate for branching the propagation of noise in the propagation direction is provided inside the cylinder, and a sound absorbing material is provided on the inner wall of the cylinder. The inner wall of the hollow cylinder has an enlarged surface that gradually expands from the noise propagation inlet side opening to the middle of the noise propagation direction, and from the middle position to the noise propagation outlet side opening continuously. Since it has a gradually expanding / contracting expansion / contraction surface, it has an expanding / contracting surface formed continuously from the inside of the cylinder to the noise propagation inlet side opening. , A stepped portion that has expanded or contracted rapidly As a result, the sound absorbing material stretched inside while maintaining the natural flow of air sufficiently absorbs the secondary noise generated by the air flowing into the inside of the cylinder while preventing turbulence. The amount of generated noise itself can be greatly suppressed. At the same time, by providing a partition plate in the cylinder, the sound deadening effect can be more effectively exhibited. Furthermore, by smoothly guiding sound waves in the direction of expansion by this expansion surface, more sound is struck by the sound absorbing material on the expansion / contraction surface side, and the amount of sound absorbed and reflected by the sound absorbing material on the expansion / contraction surface side is increased. As a result, it is possible to produce a large amount of sound interference due to the shunting of air by the partition plate, and synergistically maintain a significant silencing effect. Therefore, a sufficient silencing effect can be obtained without bending and installing the duct pipe for silencing, so that it is not necessary to secure a large space for manipulating the pipe, and the duct pipe can be shortened. In addition, the cost of the duct itself can be reduced by shortening the duct piping. Also, because it is not necessary to bend and install the pipes for noise reduction, the power load of the air supply fan and motor can be small, and the amount of electricity required for them can be small, so the electricity bill is also saved. be able to.

Further, according to the sound deadening device of the second aspect, since the branch portion between the expansion surface and the expansion / contraction surface, which is a midway position in the noise propagation direction, is substantially at the center position in the noise propagation direction, the expansion surface The sound absorbing material on the side absorbs the sound and the sound absorbing material on the expansion / contraction surface side absorbs the sound and interferes with each other most.

Further, according to the muffler of the third aspect, since the partition plate is set to be shorter than the entire length of the hollow cylindrical body, the partition plate transmits in the air flow direction. The sound can be separated into two, and the sound can be easily absorbed and reflected inside the cylinder. Therefore, each of the two separated sounds interferes with each other by the partition plate, and the sound deadening effect can be greatly improved. Sound that is not absorbed by the sound absorbing material on the expansion / contraction surface side provided inside the hollow cylindrical body is reflected by the expansion / contraction surface and propagates, for example, as it is from the outlet opening to the downstream side, and the sound and originally the noise propagation direction. By interfering with the sound propagating in, the effect of silencing is enhanced.

Further, according to the silencer of the fourth aspect, the partition plate is extended from one of the openings toward the other halfway position to a midway position on one plane along the flow direction. , The partition plate separates one sound transmitted in the direction of air flow into two, and also acts so that the sound is easily absorbed and reflected inside the cylinder, and each of the two separated sounds The partition walls interfere with each other, and the sound deadening effect can be greatly improved. Sound that is not absorbed by the sound absorbing material on the expansion / contraction surface side provided inside the hollow cylindrical body is reflected by the expansion / contraction surface and propagates, for example, as it is from the outlet opening to the downflow side, and propagates in the noise propagation direction. By interfering with noise, the effect of noise reduction is enhanced.

Further, according to the silencer of the fifth aspect, the partition plate extends from any one of the openings to a substantially central position of the entire length of the hollow cylindrical body. The sound transmitted in the direction of flow is separated into two, and at the same time, the sound is made to be easily absorbed and reflected inside the cylinder. This will cause interference with and can significantly improve the sound deadening effect. Sounds that are not absorbed by the sound absorbing material on the expansion / contraction surface side provided inside the hollow cylindrical body are reflected by the expansion / contraction surface and, for example, propagate as they are from the outflow opening to the downstream side, and those sounds and the original air flow direction. By interfering with the sound transmitted to, the effect of enhancing the sound deadening is achieved. In particular, by extending from any of the openings to the center position of the cylinder, the device can be made easier to manufacture specifically, and mass production and low cost manufacturing are possible, as well as the size of the opening and the cylinder. As a result, it becomes easier to measure the volume of noise corresponding to the entire length of the, and the effect that the volume of noise corresponding to the size can be easily standardized.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view taken along line BB in FIG. 3 of the silencer according to the embodiment.

FIG. 3 is a side view of an air inflow side of the silencer of the embodiment.

FIG. 4 is an explanatory view of the flow of air and sound in the cross section taken along the line BB of FIG. 3 of the silencer according to the embodiment.

FIG. 5 is a sectional view taken along line CC of FIG. 3;

FIG. 6 is a sectional view taken along line AA of FIG. 2;

FIG. 7 is a reference diagram of a usage state of the conventional silencer and a usage state of the silencer according to the embodiment.

FIG. 8 is an explanatory diagram of a conventional silencer.

[Explanation of symbols]

 10 Silencing Device 12 Hollow Cylindrical Body 14 Opening Part 16 Joining Part 18 Hollow Part 20 Sound Absorbing Material 22 Expanding Surface 24 Expanding / Reducing Surface 26 Partition Plate

Claims (5)

[Scope of utility model registration request] 1. A silencer provided in the middle of a duct for guiding the flow of air and having two openings in the direction of noise propagation, which silencer comprises a hollow cylindrical body. A partition plate for branching the propagation of noise in the propagation direction is provided inside the body, and a sound absorbing material is provided on the inner wall of the cylindrical body, and the inner wall of the hollow cylindrical body continues from the noise propagation inlet side opening. A muffling device having an expansion surface that gradually expands to the middle of the noise propagation direction, and a expansion and contraction surface that gradually expands and contracts continuously from the middle position to the noise propagation exit side opening. 2. The silencer according to claim 1, wherein a branch portion between the expansion surface and the expansion / contraction surface, which is a midway position in the noise propagation direction, is located at a substantially central position in the noise propagation direction. 3. The silencer according to claim 1, wherein the partition plate is set shorter than the entire length of the hollow cylindrical body. 4. The partition wall plate according to claim 1, wherein the partition plate is extended from one of the openings toward the other opening to a midway position on one plane along the noise propagation direction. Silencer. 5. The silencer according to claim 4, wherein the partition plate extends from any one of the openings to a substantially central position of the entire length of the hollow cylindrical body.