WO2021261138A1 - Silencer - Google Patents

Abstract

This silencer is provided in a duct (2) in which a passage (3) having an opening on both sides or one side is formed. The silencer is provided with: a case (4) forming a space (6) which communicates with the passage (3) in the duct (2); and one or a plurality of dividing plates (5, 5a to 5d) provided in the space (6) inside the case. At least one of the dividing plates (5, 5a to 5d) is provided in a position separated from at least a portion of a case inner wall (4b to 4e) positioned in a planar direction parallel to a boundary surface (BS) between the space inside the case and the passage inside the duct.

Description

Silencer Cross-reference to related applications

This application is based on Japanese Patent Application No. 2020-11890 filed on June 26, 2020, the contents of which are incorporated herein by reference.

This disclosure relates to a silencer.

Conventionally, a silencer that reduces noise propagating in a passage in a duct has been known.
Patent Document 1 describes a bottomed cylindrical muffling tube provided in the middle of a duct. In Patent Document 1, the duct is called a "pipeline" and the muffling pipe is called a "side branch". In Patent Document 1, the noise of the wavelength λ is reduced by setting the length of the muffling tube to λ / 4 with respect to the wavelength λ of the noise to be silenced.
Further, Patent Document 1 proposes a configuration in which a bent portion is provided in the middle of the muffling tube to suppress the amount of protrusion of the muffling tube protruding from the duct. Further, it has been proposed that a plurality of bent portions are provided in the middle of the sound deadening tube to suppress the amount of protrusion of the sound deadening tube and to lengthen the sound deadening tube to reduce noise at lower frequencies.

Japanese Unexamined Patent Publication No. 2016-29269

However, in the configuration of Patent Document 1 described above, since the frequency to be muffled is determined according to the length of the muffling tube, there is a problem that the frequency band in which the muffling effect can be obtained is narrow. In order to mute the noise in a wide band by using the configuration of Patent Document 1, it is conceivable to install a plurality of muffling tubes having different lengths in the duct. However, doing so increases the space required to install multiple muffling tubes in the duct.

The purpose of this disclosure is to provide a muffler capable of suppressing an increase in installation space and improving noise reduction characteristics.

According to one aspect of the present disclosure, it is a silencer provided in a duct having a passage having openings on both sides or one side, and forms a space communicating with the passage in the duct, and a case in the case. It is provided with one or more partition plates provided in the space. At least one of the partition plates is provided at a position away from at least a part of the inner wall of the case located in the plane direction parallel to the boundary surface between the space in the case and the passage in the duct.

As a result, since a plurality of paths through which the sound waves incident from the passages in the duct propagate are formed in the space inside the case, it is possible to widen the band of the sound waves propagating through the plurality of paths. Therefore, the noise in the duct is silenced in a wide band by the interference between the sound wave propagating through the plurality of paths and emitted to the duct again and the sound wave traveling through the passage in the duct. Therefore, this silencer can improve the noise reduction characteristic by widening the noise reduction characteristic for the noise of the passage in the duct.
Further, by providing one or a plurality of partition plates in the space inside the case, it is possible to lengthen the propagation path of the sound wave formed in the case without increasing the size of the case. Therefore, this silencer can improve the noise reduction characteristics by suppressing the increase in the installation space and reducing the noise at lower frequencies.

The reference numerals in parentheses attached to each component or the like indicate an example of the correspondence between the component or the like and the specific component or the like described in the embodiment described later.

It is a perspective view of the silencer which concerns on 1st Embodiment and the duct in which the silencer is installed. It is sectional drawing which cut the silencer and the duct shown in FIG. 1 in the plane parallel to the YZ plane. FIG. 2 is a cross-sectional view taken along the line III-III of FIG. It is an analysis figure which shows the vector of the particle velocity in the silencer which concerns on 1st Embodiment. It is a schematic diagram which shows the propagation path of the sound wave in the silencer which concerns on 1st Embodiment. It is sectional drawing of the silencer which concerns on 2nd Embodiment and the duct in which the silencer is installed. It is sectional drawing of the silencer which concerns on 3rd Embodiment and the duct in which the silencer is installed. It is sectional drawing of the silencer which concerns on 4th Embodiment and the duct in which the silencer is installed. It is an analysis figure which shows the vector of the particle velocity in the silencer which concerns on 4th Embodiment. It is a schematic diagram which shows the propagation path of the sound wave in the silencer which concerns on 4th Embodiment. It is sectional drawing of the part corresponding to FIG. 3 in the silencer which concerns on 5th Embodiment. It is sectional drawing of the silencer which concerns on 6th Embodiment and the duct in which the silencer is installed. It is sectional drawing of the XIII-XIII line of FIG. It is sectional drawing of the silencer which concerns on 7th Embodiment and the duct in which the silencer is installed. It is sectional drawing of the XV-XV line of FIG. It is an analysis figure which shows the vector of the particle velocity in the silencer which concerns on 7th Embodiment. It is a schematic diagram which shows the propagation path of the sound wave in the silencer which concerns on 7th Embodiment. It is a schematic diagram which shows the propagation path of the sound wave in the silencer which concerns on 7th Embodiment. It is sectional drawing of the silencer which concerns on 8th Embodiment and the duct in which the silencer is installed. It is sectional drawing of the XX-XX line of FIG. It is sectional drawing of the silencer which concerns on 9th Embodiment and the duct in which the silencer is installed. It is a graph which analyzed the relationship between the frequency and the noise reduction amount about 9th Embodiment and the comparative example 1 with it. FIG. 6 is a schematic diagram showing a state in which air flows through the duct with respect to Comparative Example 1. It is a perspective view of the muffler according to the tenth embodiment and the duct in which the muffler is installed. It is sectional drawing which cut the silencer and the duct shown in FIG. 24 in the plane parallel to the YZ plane. It is an analysis figure which shows the vector of the particle velocity in the silencer which concerns on 10th Embodiment. It is a schematic diagram which shows the propagation path of the sound wave in the silencer which concerns on 10th Embodiment. It is a schematic diagram which shows the propagation path of the sound wave in the comparative example 2 with respect to the tenth embodiment. It is a graph which analyzed the relationship between the frequency and the noise reduction amount about 10th Embodiment and the comparative example 2 with it. It is a graph which analyzed the relationship between the frequency and the noise reduction amount about the tenth embodiment and the ninth embodiment. It is sectional drawing of the silencer which concerns on eleventh embodiment, and the duct in which the silencer is installed. It is sectional drawing of the comparative example 3 with respect to the eleventh embodiment. It is a graph which analyzed the relationship between the frequency and the noise reduction amount about the eleventh embodiment and the comparative example 3 with it. It is sectional drawing which shows the place of installation of the silencer which concerns on 12th Embodiment in the air-conditioning unit for a vehicle. It is sectional drawing of the silencer which concerns on 13th Embodiment and the duct in which the silencer is installed. It is sectional drawing of the silencer which concerns on 14th Embodiment and the duct in which the silencer is installed.

Hereinafter, a plurality of embodiments of the present disclosure will be described with reference to the drawings. In the description of the plurality of embodiments, the same reference numerals are given to the portions that are the same or equal to each other, and the description thereof will be omitted.

Note that each drawing shows three-dimensional coordinates based on the X-axis, Y-axis, and Z-axis that are orthogonal to each other. In the following description, the direction parallel to the X axis is referred to as the X direction, the direction parallel to the Y axis is referred to as the Y direction, and the direction parallel to the Z axis is referred to as the Z direction. It should be noted that these X, Y, and Z are used for explanation, and do not limit the state in which the silencer, duct, and the like are installed.

(First Embodiment)
The first embodiment will be described with reference to the drawings. As shown in FIGS. 1 to 3, the silencer 1 of the first embodiment is provided in the duct 2 and is used to reduce the noise propagating in the passage 3 formed in the duct 2.

The duct 2 has an opening of the passage 3 on both sides or one side in the X direction, and a noise source (not shown) is arranged on one opening side of the passage 3. The shape, size, and the like of the duct 2 shown in FIGS. 1 to 3 are simplified and described for the sake of explanation. That is, the shape, size, and the like of the duct 2 can be arbitrarily set. The duct 2 corresponds to, for example, an air-conditioning case of a vehicle air-conditioning unit, an outlet duct connected to the air-conditioning case, or an exhaust pipe of an internal combustion engine. When an air conditioning case or an outlet duct is applied as the duct 2, a fan and a motor become noise sources.

As shown in FIGS. 1 to 3, the silencer 1 includes a case 4 and a partition plate 5.
The case 4 is provided on the outer wall of the duct 2. The case 4 is provided so as to project in the Y direction from the outer wall of the duct 2. The case 4 forms a space 6 inside the case 4. The space 6 in the case communicates with the passage 3 in the duct.

Note that the shapes, sizes, etc. of the cases 4 shown in FIGS. 1 to 3 are simplified for the sake of explanation. That is, the shape, size, and the like of the case 4 can be arbitrarily set according to the target muffling characteristics (that is, the frequency of the muffling noise), the restrictions of the installation space, and the like.

In the following explanation, the boundary between the space 6 in the case and the passage 3 in the duct is referred to as "boundary surface BS". In FIG. 2, the boundary surface BS is shown by a alternate long and short dash line with a reference numeral BS. Further, in FIG. 2, the virtual surface VS perpendicular to the boundary surface BS and including the center of the space 6 in the case is shown by a two-dot chain line with a reference numeral VS. In the first embodiment, nothing is provided on the boundary surface BS. As will be described later in the seventh embodiment, the boundary surface BS may be provided with a boundary layer made of a breathable material such as a perforated panel or a non-woven fabric.

Further, in the following description, a portion of the inner wall of the case 4 arranged at a position facing the boundary surface BS may be referred to as a "case ceiling 4a".

The partition plate 5 is provided in the space 6 inside the case. The partition plate 5 is provided so that the surface facing the plate thickness direction is along the boundary surface BS. The term "along the boundary surface BS" includes not only a state parallel to the boundary surface BS but also a state inclined with respect to the boundary surface BS. It can also be said that the partition plate 5 is provided so that the surface facing the plate thickness direction intersects the virtual surface VS perpendicular to the boundary surface BS.

As shown in FIG. 3, the partition plate 5 is located at a position away from at least a part of the case inner walls 4b to 4e located in the plane direction parallel to the boundary surface BS between the space 6 in the case and the passage 3 in the duct. It is provided. Specifically, both ends of the partition plate 5 in the X direction are connected to the inner walls 4d and 4e in the X direction of the case 4. Further, the length L1 of the partition plate 5 in the Z direction is shorter than the length L2 of the space 6 in the case in the Z direction. Therefore, as shown in FIGS. 2 and 3, both ends of the partition plate 5 in the Z direction are provided at positions separated from the inner wall of the case 4 in the Z direction. In other words, the partition plate 5 is provided at a position away from one case inner wall 4b and the other case inner wall 4c facing each other across the virtual surface VS. Therefore, a gap is formed between both ends of the partition plate 5 in the Z direction and the inner walls 4b and 4c of the case 4 in the Z direction, respectively. As a result, a plurality of paths through which sound waves incident from the passage 3 in the duct propagate are formed in the space 6 in the case, including one gap and the other gap facing each other across the virtual surface VS. In the following description, the path through which the sound wave propagates may be simply referred to as the "propagation path". Further, in the present specification, the “gap” refers to a part constituting the propagation path, and also includes a configuration filled with a porous material as in the eleventh embodiment described later.

FIG. 4 is an analysis diagram showing a vector of particle velocity. The analysis of FIG. 4 relates to a configuration in which a boundary layer is provided at the boundary between the space 6 in the case and the passage 3 in the duct, in addition to the configuration described in the first embodiment. From this analysis result, it is possible to read the propagation path of the sound wave.

FIG. 5 is a diagram schematically showing a part of the sound wave propagation path based on the analysis result of FIG. As shown by the arrow SW1 in FIG. 5, a part of the sound wave incident on the space 6 in the case from the passage 3 in the duct passes through one gap in the Z direction from the region on the duct 2 side of the partition plate 5. Proceed to the area on the case ceiling 4a side from the partition plate 5. Further, as shown by the arrow SW2, the other part of the sound wave incident on the space 6 in the case from the passage 3 in the duct passes through the other gap in the Z direction from the region on the duct 2 side of the partition plate 5. , Proceed to the area on the case ceiling 4a side from the partition plate 5. In this way, a plurality of propagation paths are formed in the space 6 in the case by the partition plate 5. Therefore, it is possible to widen the frequency band of the sound wave propagating in the space 6 in the case by a plurality of propagation paths. Further, by increasing the length of the plurality of propagation paths, it is possible to reduce the frequency of the sound wave propagating in the space 6 in the case. Then, the noise in the duct can be silenced by the interference between the sound wave propagating through the plurality of paths and emitted to the duct 2 again and the sound wave traveling through the passage 3 in the duct.

The silencer 1 of the first embodiment described above has the following effects.
In the first embodiment, the partition plate 5 provided in the space 6 in the case is perpendicular to the boundary surface BS and faces the virtual surface VS including the center of the space 6 in the case, and the inner wall 4b of one case and the other. It is provided at a position away from both of the inner walls 4c of the case.
As a result, since a plurality of propagation paths are formed in the space 6 in the case, it is possible to widen the sound wave propagating through the plurality of propagation paths. Therefore, the noise in the duct is silenced in a wide band by the interference between the sound wave propagating through the plurality of propagation paths and being emitted to the duct 2 again and the sound wave traveling through the passage 3 in the duct. Therefore, the silencer 1 can improve the noise reduction characteristic by widening the noise reduction characteristic for the noise of the passage 3 in the duct.

Further, in this silencer 1, by providing the partition plate 5 in the space 6 in the case, it is possible to lengthen the propagation path of the sound wave formed in the case without increasing the size of the case 4. Therefore, the muffler 1 can improve the noise reduction characteristics by suppressing an increase in the space required for installation and reducing noise at a lower frequency.

(Second Embodiment)
The second embodiment will be described. Since the second embodiment is the same as the first embodiment in that the configuration of the partition plate 5 is changed from that of the first embodiment, only the parts different from the first embodiment will be described.

As shown in FIG. 6, in the silencer 1 of the second embodiment, the length L1 of the partition plate 5 in the Z direction is set longer than that described in the first embodiment. Specifically, the length L1 in the Z direction of the partition plate 5 is set to be more than half of the length L2 in the Z direction of the space 6 in the case. Further, it can be said that the area of the partition plate 5 is set to more than half of the area of the space 6 in the case when viewed from the Y direction. The length L1 of the partition plate 5 in the Z direction is set according to the target muffling characteristic (that is, the frequency of the muffling noise).

In the second embodiment described above, by lengthening the length L1 of the partition plate 5 in the Z direction, it is possible to extend the sound propagation path and reduce low-frequency noise.

(Third Embodiment)
The third embodiment will be described. The third embodiment is also a modification of the configuration of the partition plate 5 with respect to the first embodiment and the like, and the other parts are the same as those of the first embodiment and the like. explain.

As shown in FIG. 7, the silencer 1 of the third embodiment includes a plurality of partition plates 5a to 5d. The plurality of partition plates 5a to 5d are arranged at a predetermined distance from each other in the Y direction. In the following description, among the plurality of partition plates 5a to 5d, the partition plate arranged on the case ceiling 4a side is referred to as "first partition plate 5a", and the partition plate arranged on the boundary surface BS side is referred to as "second partition plate". It is called "partition plate 5b". Further, of the partition plates 5c and 5d arranged between the first partition plate 5a and the second partition plate 5b, the partition plate arranged in one of the Z directions is called "third partition plate 5c" and Z. The partition plate arranged on the other side in the direction is called a "fourth partition plate 5d".

The length of the first partition plate 5a and the second partition plate 5b in the Z direction is shorter than the length of the space 6 in the case in the Z direction. The first partition plate 5a and the second partition plate 5b are provided at positions where both ends in the Z direction are separated from the inner walls 4b and 4c in the Z direction of the case 4. In other words, the first partition plate 5a and the second partition plate 5b are provided at positions separated from both the one case inner wall 4b and the other case inner wall 4c facing each other with the virtual surface VS interposed therebetween. Therefore, a gap is formed between both ends of the first partition plate 5a in the Z direction and the inner walls 4b and 4c of the case 4 in the Z direction, respectively. Further, gaps are also formed between both ends of the second partition plate 5b in the Z direction and the inner walls 4b and 4c of the case 4 in the Z direction.

One end of the third partition plate 5c in the Z direction is connected to the case inner wall 4b. The other end of the fourth partition plate 5d in the Z direction is connected to the case inner wall 4c. The third partition plate 5c and the fourth partition plate 5d are provided at positions corresponding to the gaps formed between the first partition plate 5a and the second partition plate 5b and the case inner walls 4b and 4c. That is, when viewed from the Y direction, the third partition plate 5c and the fourth partition plate 5d are positioned so as to overlap the gaps formed between the first partition plate 5a and the second partition plate 5b and the case inner walls 4b and 4c. It is provided. By arranging the plurality of partition plates 5a to 5d in this way, it is possible to lengthen the plurality of propagation paths formed in the space 6 in the case.

The silencer 1 of the third embodiment described above has a wide band of noise reduction characteristics for the noise of the passage 3 in the duct by forming a plurality of propagation paths in the space 6 in the case by the plurality of partition plates 5a to 5d. Can be transformed into.
Further, the silencer 1 can also reduce low-frequency noise by lengthening the propagation path of the sound wave formed in the case by the plurality of partition plates 5a to 5d.

(Fourth Embodiment)
The fourth embodiment will be described. The fourth embodiment is a modification of the configuration of the partition plate 5 with respect to the third embodiment, and the other parts are the same as those of the third embodiment. Therefore, only the parts different from the third embodiment and the like will be described. ..

As shown in FIG. 8, the silencer 1 of the fourth embodiment also includes a plurality of partition plates 5a to 5d. A gap is formed between both ends of the first partition plate 5a in the Z direction and the inner walls 4b and 4c of the case 4 in the Z direction, respectively. There are also gaps between them. The third partition plate 5c and the fourth partition plate 5d are provided at positions corresponding to the gaps formed between the first partition plate 5a and the second partition plate 5b and the case inner walls 4b and 4c. Further, in the fourth embodiment, when viewed from the Y direction, a part of the first partition plate 5a and the second partition plate 5b and a part of the third partition plate 5c and the fourth partition plate 5d are arranged so as to overlap each other. Has been done. Therefore, by arranging the plurality of partition plates 5a to 5d in this way, it is possible to make the plurality of propagation paths formed in the space 6 in the case longer.

FIG. 9 is an analysis diagram showing a vector of particle velocity. The analysis of FIG. 9 relates to a configuration in which a boundary layer is provided at the boundary between the space 6 in the case and the passage 3 in the duct, in addition to the configuration described in the fourth embodiment. From this analysis result, it is possible to read the propagation path of the sound wave.

FIG. 10 is a diagram schematically showing a part of the sound wave propagation path based on the analysis result of FIG. As shown by the arrow SW3 in FIG. 10, a part of the sound wave incident on the space 6 in the case from the passage 3 in the duct is from the region on the duct 2 side of the second partition plate 5b to the Z of the second partition plate 5b. There is one that goes through one of the gaps in the direction to the region between the first partition plate 5a and the second partition plate 5b. Further, as shown by the arrow SW3, a part of the sound wave passes from the region between the first partition plate 5a and the second partition plate 5b through one gap in the Z direction of the first partition plate 5a. There is something that goes to the area between the case ceiling 4a and the first partition plate 5a.
Further, as shown by the arrow SW4, the other part of the sound wave incident on the space 6 in the case from the passage 3 in the duct is from the region on the duct 2 side of the second partition plate 5b to the second partition plate 5b. There is one that passes through the other gap in the Z direction and advances to the region between the first partition plate 5a and the second partition plate 5b. Further, as shown by the arrow SW4, the other part of the sound wave passes through the other gap in the Z direction of the first partition plate 5a from the region between the first partition plate 5a and the second partition plate 5b. , Some go to the area between the case ceiling 4a and the first partition plate 5a.

In this way, since a plurality of propagation paths are formed in the space 6 in the case by the plurality of first partition plates 5a to 5d, it is possible to widen the frequency band of the sound wave propagating in the space 6 in the case. be. Further, by arranging so that a part of the plurality of first partition plates 5a to 5d overlaps when viewed from the Y direction, the length of the plurality of propagation paths is made longer, and the sound wave propagating in the space 6 in the case is transmitted. It is possible to make the frequency lower. The noise in the duct can be silenced by the interference between the sound wave propagating through the plurality of paths and emitted to the duct 2 again and the sound wave traveling through the passage 3 in the duct.

The silencer 1 of the fourth embodiment described above can widen the noise reduction characteristic of the passage 3 in the duct by forming a plurality of propagation paths in the space 6 in the case.
Further, the silencer 1 can also reduce low-frequency noise by lengthening the propagation path of the sound wave formed in the case.

(Fifth Embodiment)
A fifth embodiment will be described. The fifth embodiment is different from the first embodiment because the configuration of the partition plate 5 is changed from the silencer 1 described in the first embodiment, and the other parts are the same as those of the first embodiment. Only the part will be explained.

FIG. 11 is a cross-sectional view of a portion of the silencer 1 according to the fifth embodiment, corresponding to the portion shown in FIG. 3 of the first embodiment. As shown in FIG. 11, in the fifth embodiment, both ends of the partition plate 5 in the Z direction are connected to the inner walls 4b and 4c in the Z direction of the case 4. Further, the length of the partition plate 5 in the X direction is shorter than the length of the space 6 in the case in the X direction. Therefore, both ends of the partition plate 5 in the X direction are provided at positions separated from one inner wall 4d and the other inner wall 4e of the case 4 in the X direction. Therefore, a gap is formed between both ends of the partition plate 5 in the X direction and the inner walls 4d and 4e of the case 4 in the X direction, respectively. As a result, a plurality of propagation paths are formed in the space 6 in the case.

The fifth embodiment described above can also exert the same action and effect as the first embodiment. That is, the noise reduction effect does not change depending on the direction in which the partition plate 5 and the inner wall of the case are connected.

(Sixth Embodiment)
The sixth embodiment will be described. In the sixth embodiment, the configuration of the partition plate 5 is changed with respect to the silencer 1 described in the first embodiment and the like, and the other parts are the same as those in the first embodiment and the like. Only the parts that differ from the above will be explained.

As shown in FIGS. 12 and 13, the silencer 1 of the sixth embodiment includes a connecting member 7 for connecting the case ceiling 4a and the partition plate 5. The partition plate 5 is supported by the connecting member 7 in the space 6 in the case. Therefore, the partition plate 5 is provided at a position away from the inner wall in the Z direction and the inner wall in the X direction of the case 4.

Specifically, as shown in FIG. 13, the length L1 of the partition plate 5 in the Z direction is shorter than the length L2 of the space 6 in the case in the Z direction. Therefore, both ends of the partition plate 5 in the Z direction are provided at positions separated from the inner walls 4b and 4c in the Z direction of the case 4. Therefore, a gap is formed between both ends of the partition plate 5 in the Z direction and the inner walls 4b and 4c of the case 4 in the Z direction, respectively. Further, the length L3 of the partition plate 5 in the X direction is shorter than the length L4 of the space 6 in the case in the X direction. Therefore, both ends of the partition plate 5 in the X direction are provided at positions away from the inner walls 4d and 4e in the X direction of the case 4. Therefore, gaps are also formed between both ends of the partition plate 5 in the X direction and the inner walls 4d and 4e of the case 4 in the X direction. Therefore, in the sixth embodiment, a gap is formed between the partition plate 5 and the inner wall of the case over the entire circumference. As a result, a plurality of propagation paths are formed in the space 6 in the case.

As illustrated by the arrows SW5 and SW6 in FIG. 13, the sound wave incident on the space 6 in the case from the passage 3 in the duct travels along the diagonal line of the partition plate 5 or along the side of the partition plate 5. There are things that go on like this. In this way, a plurality of propagation paths are formed in the space 6 in the case by the partition plate 5. Therefore, in the sixth embodiment, it is possible to widen the frequency band of the sound wave propagating in the space 6 in the case by making the lengths of the plurality of propagation paths different.

The silencer 1 of the sixth embodiment described above can also widen the noise reduction characteristic of the passage 3 in the duct by forming a plurality of propagation paths in the space 6 in the case.

(7th Embodiment)
The seventh embodiment will be described. In the seventh embodiment, the configuration of the partition plate 5 is changed with respect to the silencer 1 described in the first embodiment and the like, and the other parts are the same as those in the first embodiment and the like. Only the parts that differ from the above will be explained.

As shown in FIGS. 14 and 15, in the seventh embodiment, the partition plate 5 is located in the plane direction parallel to the boundary surface BS between the space 6 in the case and the passage 3 in the duct, and the inner walls 4b to 4e of the case are located. It is installed at a position away from at least a part of. Specifically, the partition plate 5 is provided at a position away from one inner wall 4b in the Z direction of the case 4. Further, the partition plate 5 is connected to the other inner wall 4c in the Z direction of the case 4, and is also connected to both inner walls 4d and 4e in the X direction of the case 4. Therefore, a gap is formed only between one end of the partition plate 5 in the Z direction and one inner wall 4b of the case 4 in the Z direction. Even with such a configuration, a plurality of paths through which sound waves incident from the passage 3 in the duct propagate are formed in the space 6 in the case.

FIG. 16 is an analysis diagram showing a vector of particle velocity. From this analysis result, it is possible to read the propagation path of the sound wave.

FIG. 17 is a diagram schematically showing a part of the sound wave propagation path based on the analysis result of FIG. As illustrated by the arrow SW7 in FIG. 17, a part of the sound wave incident on the space 6 in the case from the passage 3 in the duct is separated from the case from a region relatively close to one inner wall 4b in the Z direction of the case 4. It passes through the gap with the plate 5 and proceeds from the partition plate 5 to the area on the case ceiling 4a side. Further, as shown by the arrow SW8, the other part of the sound wave incident on the space 6 in the case from the passage 3 in the duct is separated from the case from the region relatively close to the other inner wall 4c in the Z direction of the case 4. It passes through the gap with the plate 5 and proceeds from the partition plate 5 to the area on the case ceiling 4a side. In this way, a plurality of propagation paths are formed in the space 6 in the case by the partition plate 5.

Further, as schematically shown by arrows SW9 and SW10 in FIG. 18, sound waves incident on the space 6 in the case from the passage 3 in the duct travel along the diagonal line of the partition plate 5 or the partition plate. Some go along the side of 5. In this way, a plurality of propagation paths are formed in the space 6 in the case by the partition plate 5.

As described above, also in the configuration of the seventh embodiment, it is possible to widen the frequency band of the sound wave propagating in the space 6 in the case by forming a plurality of propagation paths in the case. Further, by increasing the length of the plurality of propagation paths, it is possible to reduce the frequency of the sound wave propagating in the space 6 in the case. Then, the noise in the duct can be silenced by the interference between the sound wave propagating through the plurality of paths and emitted to the duct 2 again and the sound wave traveling through the passage 3 in the duct.

In the seventh embodiment described above, the configuration in which the partition plate 5 is provided at a position away from only one inner wall 4b in the Z direction of the case 4 has been described, but the partition plate 5 is not limited to this. It suffices if it is provided at a position away from at least a part of the case inner walls 4b to 4e. That is, the partition plate 5 may be separated from only the other inner wall 4c in the Z direction of the case 4. Alternatively, the partition plate 5 may be separated from only one inner wall 4d in the X direction of the case 4. Alternatively, the partition plate 5 may be separated from only the other inner wall 4e in the X direction of the case 4.

(8th Embodiment)
The eighth embodiment will be described. In the eighth embodiment, the configuration of the partition plate 5 is changed with respect to the silencer 1 described in the first embodiment and the like, and the other parts are the same as those in the first embodiment and the like. Only the parts that differ from the above will be explained.

As shown in FIGS. 19 and 20, in the eighth embodiment, the partition plate 5 is provided at a position away from both inner walls 4b and 4c in the Z direction of the case 4, and one inner wall in the X direction of the case 4 is provided. It is provided at a position far from 4d. Further, the partition plate 5 is connected to the other inner wall 4e of the case 4 in the X direction. Therefore, a gap is formed between both ends of the partition plate 5 in the Z direction and the inner walls 4b and 4c of both the Z directions of the case 4, and one end of the partition plate 5 in the X direction and the X direction of the case 4. A gap is formed between the inner wall and the inner wall 4d. As a result, a plurality of paths through which sound waves incident from the passage 3 in the duct propagate are formed in the space 6 in the case.

Even in such a configuration of the eighth embodiment, the same action and effect as those of the above-mentioned first embodiment and the like can be obtained.

(9th Embodiment)
A ninth embodiment will be described. The ninth embodiment is the same as the fourth embodiment in that the boundary layer is added to the silencer 1 described in the fourth embodiment and the like, and therefore, only the parts different from the fourth embodiment will be described. do.

As shown in FIG. 21, the silencer 1 of the ninth embodiment includes a boundary layer 8 at the boundary between the space 6 in the case and the passage 3 in the duct. The boundary layer 8 partitions the space 6 in the case and the passage 3 in the duct, and secures the air permeability between the space 6 in the case and the passage 3 in the duct. As the boundary layer 8, a breathable material such as a perforated panel or a non-woven fabric can be adopted. By balancing the acoustic impedance of the boundary layer 8 and the acoustic impedance of the space 6 in the case, it is possible to widen or lower the frequency of the sound deadening characteristic.

The graph shown in FIG. 22 is an analysis of the relationship between the frequency and the noise reduction amount (that is, the muffling characteristic) for an example of the ninth embodiment and the first comparative example thereof. In addition, in the example of the 9th embodiment, the perforated panel is adopted as the boundary layer 8. On the other hand, the first comparative example with respect to the ninth embodiment is a configuration in which the boundary layer 8 is removed from the configuration of the ninth embodiment, that is, the same as the fourth embodiment described with reference to FIGS. 8 to 10. It is a composition.

In the graph of FIG. 22, the muffling characteristic according to the configuration of the ninth embodiment is shown by the solid line A1, and the muffling characteristic according to the first comparative example is shown by the broken line B1. The frequency of the peak value of the solid line A1 is lower than the frequency of the peak value of the broken line B1. Further, the frequency range indicated by the arrow A2 for the solid line A1 is wider than the frequency range indicated by the arrow B2 for the broken line B1. As described above, the silencer 1 of the ninth embodiment is provided with the boundary layer 8 so that the silencer characteristic can be widened or lowered in frequency as compared with the first comparative example.

Next, FIG. 23 shows a state in which gas flows through the passage 3 in the duct in the first comparative example (that is, the same configuration as that of the fourth embodiment) with respect to the ninth embodiment.

When gas flows through the passage 3 in the duct, noise may be generated by the air flow entering the space 6 in the case. Further, as shown by the arrow AE in FIG. 23, noise may be generated when the airflow flowing through the passage 3 in the duct hits the inner wall of the case 4 and the airflow is turbulent. In this way, when gas flows through the passage 3 in the duct, by providing the case 4 on the wall of the duct 2, new noise different from the noise source (not shown) arranged on one opening side of the duct 2 is generated. May occur.

On the other hand, in the silencer 1 of the ninth embodiment shown in FIG. 21, the boundary layer 8 can suppress the airflow flowing through the passage 3 in the duct from entering the space 6 in the case. Further, the boundary layer 8 can prevent the airflow flowing through the passage 3 in the duct from hitting the inner wall of the case 4. Therefore, in the silencer 1 of the ninth embodiment, even when gas flows in the passage 3 in the duct, the boundary layer 8 prevents the generation of new noise by providing the case 4 on the wall of the duct 2, so that the noise is generated. The reduction effect can be further improved.

(10th Embodiment)
The tenth embodiment will be described. The tenth embodiment is different from the ninth embodiment because the configuration of the partition plate 5 is changed from the silencer 1 described in the ninth embodiment, and the other parts are the same as those of the ninth embodiment. Only the part will be explained.

As shown in FIGS. 24 and 25, the silencer 1 of the tenth embodiment includes the first to third partition plates 5a to 5c described in the fourth embodiment, and includes the fourth partition plate 5d. No. Therefore, in the tenth embodiment, the plurality of partition plates 5a to 5c are the total area of the portions arranged on one side of the virtual surface VS including the center of the space 6 in the case and perpendicular to the boundary surface BS. , Is arranged so as to be non-symmetrical with the total area of the parts arranged on the other side. By arranging the plurality of partition plates 5a to 5c in this way, it is possible to make the lengths of the plurality of propagation paths formed in the space 6 in the case significantly different.

FIG. 26 is an analysis diagram showing a vector of particle velocity in the configuration of the tenth embodiment. From this analysis result, it is possible to read the propagation path of the sound wave.

FIG. 27 is a diagram schematically showing a part of the sound wave propagation path based on the analysis result of FIG. 26. As shown by the arrow SW11 in FIG. 27, a part of the sound wave incident on the space 6 in the case from the passage 3 in the duct is from the region on the duct 2 side of the second partition plate 5b to the Z of the second partition plate 5b. There is one that goes through one of the gaps in the direction to the region between the first partition plate 5a and the second partition plate 5b. Further, as shown by the arrow SW11, a part of the sound wave passes from the region between the first partition plate 5a and the second partition plate 5b through one gap in the Z direction of the first partition plate 5a. There is something that goes to the area between the case ceiling 4a and the first partition plate 5a.
Further, as shown by the arrow SW12, the other part of the sound wave incident on the space 6 in the case from the passage 3 in the duct is from the region on the duct 2 side of the second partition plate 5b to the second partition plate 5b. There is one that passes through the other gap in the Z direction and advances to the region between the first partition plate 5a and the second partition plate 5b. Further, as shown by the arrow SW12, the other part of the sound wave passes from the other gap in the Z direction of the second partition plate 5b through the other gap in the Z direction of the first partition plate 5a to the case ceiling. There is something that goes to the area between the 4a and the first partition plate 5a.
Among the propagation paths shown by the arrows SW11, those that proceed to the region between the case ceiling 4a and the first partition plate 5a are the propagation paths shown by the arrow SW12 between the case ceiling 4a and the first partition plate 5a. It is longer than the one that goes to the area in between.

As described above, in the tenth embodiment, the length of the propagation path formed on one side of the virtual surface VS and the other by asymmetrically arranging the plurality of partition plates 5a to 5c across the virtual surface VS. It will be different from the length of the propagation path formed on the side. Therefore, it is possible to widen the band of sound waves propagating through a plurality of propagation paths formed in the space 6 in the case. Therefore, the silencer 1 can further widen the sound deadening characteristic for the noise of the passage 3 in the duct.

Here, as a second comparative example with respect to the tenth embodiment, FIG. 28 shows a bottomed tubular muffling tube 10. The muffling tube 10 shown in FIG. 28 corresponds to an example of the configuration disclosed in Patent Document 1 described above. A bent portion 11 is provided in the middle of the sound deadening pipe 10, and the protruding amount H2 of the sound deadening pipe 10 protruding from the duct 2 is suppressed. It is assumed that the protrusion amount H2 of the silencer tube 10 of the second comparative example shown in FIG. 28 and the protrusion amount H1 of the case 4 of the silencer 1 of the tenth embodiment shown in FIG. 25 are the same.

As shown by the arrows SW13 and SW14 in FIG. 28, the sound wave incident on the muffling tube 10 from the duct 2 is reflected at the deep part of the muffling tube 10 and is discharged to the duct 2 again through the muffling tube 10. The noise in the duct is muted by the interference between the sound wave emitted from the sound deadening pipe 10 to the duct 2 and the sound wave traveling through the passage 3 in the duct. However, in the configuration of this second comparative example, since the frequency to be muffled is determined according to the length of the muffling tube 10, there is a problem that the frequency band in which the muffling effect can be obtained is narrow.

The graph shown in FIG. 29 is an analysis of the relationship between the frequency and the noise reduction amount (that is, the muffling characteristic) for the tenth embodiment and the second comparative example.
In the graph of FIG. 29, the muffling characteristic according to the configuration of the tenth embodiment is shown by the solid line C1, and the muffling characteristic according to the second comparative example is shown by the broken line D1. The frequency of the peak value of the solid line C1 is lower than the frequency of the peak value of the broken line D1. Further, the frequency range indicated by the arrow C2 for the solid line C1 is much wider than the frequency range indicated by the arrow D2 for the broken line D1. As described above, the silencer 1 of the tenth embodiment has different lengths of the plurality of propagation paths formed in the space 6 in the case, and further, the lengths of the plurality of propagation paths are lengthened. , It is possible to widen the band and lower the frequency of the sound deadening characteristic as compared with the second comparative example.

Further, the graph shown in FIG. 30 is an analysis of the muffling characteristics (that is, the relationship between the frequency and the noise reduction amount) for the tenth embodiment and the ninth embodiment.
In the graph of FIG. 30, the muffling characteristic according to the configuration of the tenth embodiment is shown by the solid line C1, and the muffling characteristic according to the configuration of the ninth embodiment is shown by the broken line A1. The frequency of the peak value of the solid line C1 is higher than the frequency of the peak value of the broken line A1, but the frequency range indicated by the arrow C2 for the solid line C1 is much higher than the frequency range indicated by the arrow A2 for the broken line A1. It is wide. As described above, the silencer 1 of the tenth embodiment is different from the silencer 1 of the ninth embodiment by making the lengths of the plurality of propagation paths formed in the space 6 in the case different. It is possible to widen the muffling characteristics.

As for the configuration of the tenth embodiment, if the length of the plurality of propagation paths is increased by increasing the number of partition plates 5 or extending the length of the partition plates 5, the muffling characteristics can be further lowered. It is possible to do.

In the tenth embodiment described above, the plurality of partition plates 5a to 5c provided in the silencer 1 are arranged on one side of the virtual surface VS perpendicular to the boundary surface BS and including the center of the space 6 in the case. The total area of the parts and the total area of the parts arranged on the other side are arranged so as to be non-symmetrical.
As a result, the propagation path of the sound wave formed in the space 6 in the case differs between the length of the propagation path formed on one side of the virtual surface VS and the length of the propagation path formed on the other side. Will be. Therefore, it is possible to widen the band of sound waves propagating through a plurality of propagation paths formed in the space 6 in the case. Therefore, the silencer 1 of the tenth embodiment can further widen the sound deadening characteristic for the noise of the passage 3 in the duct.

(11th Embodiment)
The eleventh embodiment will be described. The eleventh embodiment is different from the tenth embodiment because the configuration inside the case is changed with respect to the silencer 1 described in the tenth embodiment and the other parts are the same as the tenth embodiment. Will be explained only.

As shown in FIG. 31, in the silencer 1 of the eleventh embodiment, the space 6 in the case is filled with the porous material 9 having air permeability. As the porous material 9, for example, urethane, glass wool, or the like is adopted. Due to the acoustic impedance of the porous material 9, it is possible to widen or lower the frequency of the sound deadening characteristic.

In the eleventh embodiment, by filling the space 6 in the case with the porous material 9, the configuration for fixing the partition plate 5 becomes unnecessary, and the configuration of the silencer 1 can be simplified.

On the other hand, if the partition plate 5 is fixed to the inner wall of the case 4, the porous material 9 filled in the space 6 in the case can be prevented from being displaced (that is, biased or moved), and thus used for a long period of time. It is possible to suppress the deterioration of the muffling characteristics due to.

Here, FIG. 32 shows a third comparative example with respect to the eleventh embodiment. The silencer 1 of the third comparative example is one in which the space 6 in the case is filled with only the porous material 9, and does not include the partition plate 5.

The graph shown in FIG. 33 is an analysis of the relationship between the frequency and the noise reduction amount (that is, the muffling characteristic) for the configuration of the eleventh embodiment and the third comparative example thereof.
In the graph of FIG. 33, the muffling characteristic according to the configuration of the eleventh embodiment is shown by the solid line F, and the muffling characteristic according to the third comparative example is shown by the broken line G. At a frequency of about 650 Hz or less, the noise reduction amount of the solid line F is larger than the noise reduction amount of the broken line G. As described above, the silencer 1 of the eleventh embodiment is provided with the partition plate 5 together with the porous material 9 in the space 6 in the case, so that the low frequency sound absorption characteristics can be improved as compared with the third comparative example. It is possible.

(12th Embodiment)
A twelfth embodiment will be described. The twelfth embodiment describes a mode in which the muffler 1 is installed in the vehicle air-conditioning unit.

As shown in FIG. 34, the vehicle air conditioning unit 20 includes an air conditioning case 21, an evaporator 22, a heater core 23, an air mix door 24, a blowout opening door 25, and the like.
The air conditioning case 21 is a member corresponding to the duct 2 described in the first to eleventh embodiments. The air conditioning case 21 forms the outer shell of the air conditioning unit 20. Inside the air conditioning case 21, a passage 3 through which air flows is formed. In FIG. 34, the flow direction of the air in the passage 3 is indicated by a white arrow. Further, the air conditioning case 21 has a plurality of blowout openings 26 for blowing out air into a predetermined region in the vehicle interior on the downstream side of the passage 3 in the air flow direction. An outlet duct (not shown) may be connected to the outlet opening 26.

Inside the air conditioning case 21, an evaporator 22, a heater core 23, an air mix door 24, a blowout opening door 25, and the like are provided.

The evaporator 22 is a heat exchanger for cooling the air flowing through the passage 3. The evaporator 22 constitutes a part of a refrigeration cycle (not shown). The evaporator 22 exchanges heat between the refrigerant flowing inside the evaporator 22 and the air passing through the evaporator 22 to evaporate the refrigerant and cool the air.

The heater core 23 is a heat exchanger for heating the air flowing through the passage 3. The heater core 23 exchanges heat between the engine cooling water or high-pressure refrigerant flowing inside the heater core 23 and the air passing through the heater core 23, and heats the air by the heat of the engine cooling water or the high-pressure refrigerant.

An air mix door 24 is provided between the evaporator 22 and the heater core 23 in the passage 3 in the air conditioning case. The air mix door 24 adjusts the ratio of the air that bypasses the heater core 23 after passing through the evaporator 22 and the air that passes through the heater core 23 after passing through the evaporator 22.

The outlet door 25 is provided in each of the plurality of outlets 26, and the opening area of the outlet 261 is adjusted.

The silencer 1 of the twelfth embodiment is provided on the outside or the inside of the air conditioning case 21 in order to reduce the noise propagating in the passage 3 in the air conditioning case 21. In FIG. 34, the locations where it is preferable to install the silencer 1 with respect to the air conditioning case 21 are exemplifiedly shown by broken lines P1 to P3. In addition, one or a plurality of silencers 1 may be installed in the air conditioning case 21. By installing the silencer 1 in the air-conditioning case 21, it is possible to reduce the noise emitted from the air-conditioning device into the vehicle interior and improve the air-conditioning performance (that is, the comfort of the occupant).

Although not shown, the silencer 1 may be installed in the outlet duct connected to the outlet opening 26 of the air conditioning case 21. Even so, similarly to the above, the noise emitted from the air conditioner into the vehicle interior can be reduced and the air conditioning performance can be improved.

(13th Embodiment)
The thirteenth embodiment will be described. The thirteenth embodiment is a modification of the method of installing the silencer 1 with respect to the duct 2 with respect to the first embodiment and the like, and the other aspects are the same as those of the first embodiment and the like. Only the different parts will be described.

As shown in FIG. 35, in the silencer 1 of the thirteenth embodiment, a part of the case 4 on the boundary layer 8 side enters the passage 3 in the duct, and a part of the case 4 on the ceiling side is in the duct 2. It protrudes from the outer wall in the Y direction. Even in such a configuration of the thirteenth embodiment, the same effects as those of the first to twelfth embodiments described above can be obtained.

(14th Embodiment)
The fourteenth embodiment will be described. The 14th embodiment is also a modification of the installation method of the silencer 1 with respect to the duct 2 with respect to the 1st embodiment and the like, and the other aspects are the same as those of the 1st embodiment and the like. Only the different parts will be described.

As shown in FIG. 36, in the silencer 1 of the 14th embodiment, the entire case 4 is inserted into the passage 3 in the duct. Even in such a configuration of the 14th embodiment, the same effects as those of the 1st to 13th embodiments described above can be obtained.

(Other embodiments)
(1) In each of the above-described embodiments, the silencer 1 includes 1 to 4 partition plates 5, 5a to 5d, but the present invention is not limited to this, and the number of partition plates 5 may be arbitrarily set. Is possible. Further, the partition plate 5 may have any shape, and may be a flat surface or a curved surface.

(2) In each of the above-described embodiments, the silencer 1 includes a rectangular parallelepiped or cubic case 4, but the case 4 is not limited to this, and any shape can be adopted. Further, the wall of the case 4 may be a flat surface or a curved surface.

The present disclosure is not limited to the above-described embodiment, and can be changed as appropriate. Further, the above embodiments are not unrelated to each other, and can be appropriately combined unless the combination is clearly impossible. Further, in each of the above embodiments, it goes without saying that the elements constituting the embodiment are not necessarily essential except when it is clearly stated that they are essential or when they are clearly considered to be essential in principle. stomach. Further, in each of the above embodiments, when numerical values such as the number, numerical values, quantities, and ranges of the constituent elements of the embodiment are mentioned, when it is clearly stated that they are particularly essential, and when it is clearly limited to a specific number in principle. It is not limited to the specific number except when it is done. Further, in each of the above embodiments, when the shape, positional relationship, etc. of the constituent elements are referred to, the shape, unless otherwise specified or limited in principle to a specific shape, positional relationship, etc. It is not limited to the positional relationship.

(summary)
According to the first aspect shown in part or all of the above-described embodiment, the silencer provided in the duct having a passage having openings on both sides or one side provides a space communicating with the passage in the duct. It includes a case to be formed and one or a plurality of partition plates provided in the space inside the case. At least one of the partition plates is provided at a position away from at least a part of the inner wall of the case located in the plane direction parallel to the boundary surface between the space in the case and the passage in the duct.

According to the second aspect, at least one of the partition plates is one that is perpendicular to the boundary surface between the space in the case and the passage in the duct and faces the virtual surface including the center of the space in the case. It is provided at a position away from the inner wall of the case and the inner wall of the other case.

According to a third aspect, the silencer further comprises a boundary layer provided at the boundary between the space in the case and the passage in the duct. The boundary layer separates the space inside the case from the passage inside the duct, and secures the ventilation between the space inside the case and the passage inside the duct.
This makes it possible to widen the band or reduce the frequency of the sound deadening characteristics by adjusting the material and thickness of the boundary layer, the size of the vents of the boundary layer, and the like.
Further, when gas flows in the passage in the duct, the boundary layer suppresses the air flow from entering the space in the case. Further, the boundary layer suppresses that the airflow flowing through the passage in the duct hits the inner wall of the case and the airflow is turbulent. Therefore, this muffler can improve the noise reduction effect by preventing the generation of new noise due to the provision of the case by the boundary layer.

According to the fourth viewpoint, the passage in the duct is configured to allow gas to flow.
As a result, the boundary layer can prevent the airflow flowing through the passage in the duct from entering the space inside the case. In addition, the boundary layer can prevent the airflow flowing through the passage in the duct from hitting the inner wall of the case and disturbing the airflow. Therefore, this silencer can improve the noise reduction effect even when gas flows in the passage in the duct.

According to the fifth aspect, the plurality of partition plates have a predetermined partition plate and another partition plate. The predetermined partition plate and the other partition plates are arranged at a predetermined distance in a direction perpendicular to the boundary surface between the space in the case and the passage in the duct. Further, the predetermined partition plate and the other partition plate are arranged at positions corresponding to the gap between the predetermined partition plate and the inner wall of the case. Further, the predetermined partition plate and the other partition plate are arranged so that a part of the predetermined partition plate and a part of the other partition plate overlap each other when viewed from a direction perpendicular to the boundary surface.
This makes it possible to lengthen the propagation path of the sound wave formed in the case without increasing the size of the case. Therefore, this silencer can improve the noise reduction characteristics by suppressing the increase in the installation space and reducing the noise at lower frequencies.

According to the sixth aspect, the plurality of partition plates are arranged on one side of a virtual surface perpendicular to the boundary surface between the space in the case and the passage in the duct and including the center of the space in the case. The total area of the parts and the total area of the parts arranged on the other side are arranged so as to be non-symmetrical.
As a result, the propagation path of the sound wave formed in the space inside the case differs between the length of the propagation path formed on one side of the virtual surface and the length of the propagation path formed on the other side. .. Therefore, it is possible to widen the band of sound waves propagating through a plurality of propagation paths formed in the space inside the case. Therefore, this silencer can further widen the sound deadening characteristic for the noise of the passage in the duct.

According to the seventh aspect, the space inside the case is filled with a porous material having breathability.
Thereby, by selecting the material of the porous material, it is possible to widen the band and lower the frequency of the sound deadening characteristic.
Further, by filling the space inside the case with a porous material, a configuration for fixing the partition plate becomes unnecessary, and the configuration of the silencer can be simplified.
On the other hand, if the partition plate is fixed to the inner wall of the case or the like, the position of the porous material filled in the space inside the case can be prevented from shifting, so that the change in sound deadening characteristics due to long-term use can be suppressed.

Claims (7)

1. A silencer provided in a duct (2) having a passage (3) having openings on both sides or one side.
   A case (4) forming a space (6) communicating with a passage in the duct, and a case (4).
   A partition plate (5, 5a to 5d) provided in the space inside the case is provided.
   At least one of the partition plates is located away from at least a part of the case inner wall (4b to 4e) located in the plane direction parallel to the boundary surface (BS) between the space in the case and the passage in the duct. A silencer installed in.
2. At least one of the partition plates is provided at a position perpendicular to the boundary surface and away from the inner wall of one case and the inner wall of the other case facing each other across a virtual surface (VS) including the center of the space in the case. The silencer according to claim 1.
3. It is provided at the boundary between the space in the case and the passage in the duct to partition the space in the case and the passage in the duct, and to provide ventilation between the space in the case and the passage in the duct. The silencer according to claim 1 or 2, further comprising a border layer (8) to be secured.
4. The silencer according to any one of claims 1 to 3, wherein the passage in the duct is configured to allow gas to flow.
5. The plurality of partition plates have a predetermined partition plate (5a, 5b) and another partition plate (5c, 5d), and the predetermined partition plate and the other partition plate are on the boundary surface. The other partition plates are arranged at a predetermined distance in the direction perpendicular to the direction (Y), and the other partition plates are arranged at positions corresponding to the gaps between the predetermined partition plates and the inner wall of the case, and further perpendicular to the boundary surface. The silencer according to any one of claims 1 to 4, wherein a part of the predetermined partition plate and a part of the other partition plate are arranged so as to overlap each other when viewed from a certain direction.
6. The plurality of partition plates (5a to 5c) are arranged on the other side and the total area of the portions arranged on one side of the virtual surface perpendicular to the boundary surface and including the center of the space in the case. The silencer according to claim 5, which is arranged so as to be non-targeted to the total area of the portion.
7. The silencer according to any one of claims 1 to 6, wherein the space inside the case is filled with a breathable porous material (9).

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