Ventilation type silencer

Abstract

Provided is a ventilation-type muffler capable of suppressing the generation of dew condensation in a back-side space and reducing the generation of wind noise and pressure loss in a flow path space. A ventilation-type muffler is provided with: an inlet-side breather pipe; an expansion part communicating with the inlet-side breather pipe and having a larger cross-sectional area than the inlet-side breather pipe; and an outlet-side breather pipe that communicates with the expansion part and has a smaller cross-sectional area than the expansion part, the ventilation-type muffler being provided with: a flow path wall that is disposed inside the expansion part, communicates the inlet-side breather pipe and the outlet-side breather pipe, and includes a porous sound-absorbing material in at least a portion thereof; and a back-side space located on the opposite side of the flow path wall from the flow path space within the flow path wall with the flow path wall therebetween, the back-side space being formed by the flow path wall and the frame of the expansion part. The porous sound-absorbing material has one or a plurality of communication paths that communicate the flow path space and the back-side space.

Description

Technical Field

[0001] The invention relates to a ventilation type silencer. Background Art

[0002] Generally, a ventilation type silencer is known, which has: an inlet side vent pipe; an expansion portion, which is connected to the inlet side vent pipe and has a cross-sectional area larger than the cross-sectional area of ​​the inlet side vent pipe; and an outlet side vent pipe, which is connected to the expansion portion and has a cross-sectional area smaller than the cross-sectional area of ​​the expansion portion.

[0003] As such a ventilation type silencer, there is known a ventilation type silencer comprising: a flow path wall, which is arranged in an expansion portion and is composed of a porous sound absorbing member; and a back space, which is located on the opposite side of the flow path space in the flow path wall across the flow path wall and is formed by a frame of the flow path wall and the expansion portion (for example, refer to patent document 1).

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 6-167982 Summary of the invention

[0007] Technical issues to be solved by the invention

[0008] In the ventilation type silencer as described above, condensation may occur in the rear space.

[0009] Furthermore, in the ventilation type silencer as described above, it is required to reduce the generation of wind noise and pressure loss in the flow path space.

[0010] An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a ventilation type silencer which can suppress the generation of condensation in the back space and reduce the generation of wind noise and pressure loss in the flow path space.

[0011] Means for solving technical problems

[0012] In order to solve the problem, the present invention has the following configuration.

[0013] [1] A ventilation type silencer comprising: an inlet side vent pipe; an expansion portion communicating with the inlet side vent pipe and having a cross-sectional area larger than the cross-sectional area of ​​the inlet side vent pipe; and an outlet side vent pipe communicating with the expansion portion and having a cross-sectional area smaller than the cross-sectional area of ​​the expansion portion, the ventilation type silencer having:

[0014] a flow path wall disposed in the expansion portion, communicating with the inlet-side vent pipe and the outlet-side vent pipe, and including a porous sound absorbing member in at least a portion thereof; and

[0015] a back space located on the opposite side of the flow path space in the flow path wall across the flow path wall, and formed by the flow path wall and the frame of the expansion portion;

[0016] The porous sound absorbing member has one or more communication paths that communicate the flow path space with the back side space.

[0017] [2] The ventilation type silencer according to [1], wherein the opening diameter of the equivalent circle of the communication path is 1.0 mm to 50.0 mm.

[0018] [3] The ventilated silencer according to [1] or [2], wherein the permeability of the porous sound absorbing member is 1.0×10 -13 m 2 ~5.0×10 -9 m 2 or 13.0×10 -9 m 2 ~1.0×10 -5 m 2 .

[0019] [4] The ventilation type silencer according to any one of [1] to [3], wherein the total opening area of ​​the one or more communication paths is 20 mm 2 above.

[0020] [5] The ventilation type silencer according to any one of [1] to [4], wherein the plurality of communication paths are provided at intervals along a flow direction of the gas flowing in the flow path space.

[0021] [6] The ventilation type silencer according to any one of [1] to [5], wherein a dust filter is arranged in the communication passage.

[0022] [7] The ventilation type silencer according to any one of [1] to [6], wherein the frame of the expansion portion is made of resin.

[0023] [8] The ventilation type silencer according to any one of [1] to [7], wherein the temperature of the gas flowing in the flow path space is 20° C. to 80° C. and is higher than the temperature outside the expansion portion.

[0024] [9] The ventilation type silencer according to any one of [1] to [8], wherein the inner surface of the flow path space is formed by a surface of the porous sound absorbing member and a surface of the frame of the expansion portion, and the communication path is provided in contact with the surface of the frame of the expansion portion.

[0025]

[10] A ventilation type silencer according to any one of [1] to [9], wherein the porous sound absorbing member further has a first surface in contact with the gas in the flow path space and a second surface in contact with the gas in the back space, and one or more connecting paths extend from the first surface to the second surface.

[0026]

[11] A ventilation type silencer according to any one of [1] to

[10] , wherein a cross section of the flow path space perpendicular to the flow direction is rectangular, an inner surface of the flow path space is composed of respective surfaces of a porous sound absorbing member and a frame body opposed to each other in a first direction intersecting the flow direction, and respective surfaces of a pair of porous sound absorbing members opposed to each other in a second direction intersecting the flow direction and the first direction, and connecting paths are respectively formed on three surfaces of the porous sound absorbing member constituting the inner surface of the flow path space.

[0027]

[12] The ventilation type silencer according to any one of [1] to

[11] , wherein the communication path is a through hole.

[0028]

[13] The ventilation type silencer according to any one of [1] to

[12] , wherein the communication path is formed by cutting off one end of the porous sound absorbing member.

[0029] Effects of the Invention

[0030] According to the present invention, it is possible to provide a ventilation type silencer which can suppress the generation of condensation in the rear space and reduce the generation of wind noise and pressure loss in the flow path space. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a cross-sectional view conceptually showing an example of the ventilation type silencer of the present invention.

[0032] Figure 2 yes Figure 1 AA line section view.

[0033] Figure 3 This is a cross-sectional view conceptually showing another example of the ventilation type silencer of the present invention.

[0034] Figure 4 It is conceptually expressed Figure 3 A three-dimensional view of a ventilation type silencer.

[0035] Figure 5 yes Figure 4 BB line cross-sectional view.

[0036] Figure 6 This is a cross-sectional view conceptually showing another example of the ventilation type silencer of the present invention.

[0037] Figure 7It is a perspective view conceptually showing another example of the ventilation type silencer of the present invention.

[0038] Figure 8 is along Figure 7 CC line section view.

[0039] Fig. 9 This is a perspective view conceptually showing another example of the ventilation type silencer of the present invention.

[0040] Fig.10 is along Fig. 9 DD line cross-sectional view.

[0041] Fig.11 This is a perspective view conceptually showing another example of the ventilation type silencer of the present invention.

[0042] Fig.12 This is a diagram showing another example of the communication path provided in the porous sound absorbing member.

[0043] Fig.13 This is a diagram showing another example of the communication path provided in the porous sound absorbing member.

[0044] Fig.14 This is a diagram showing another example of the communication path provided in the porous sound absorbing member.

[0045] Fig.15 This is a diagram showing another example of the communication path provided in the porous sound absorbing member.

[0046] Fig.16 This is a diagram showing another example of the communication path provided in the porous sound absorbing member.

[0047] Fig.17 This is a front view conceptually showing the first embodiment of the ventilation type silencer of the present invention.

[0048] Fig.18 It is a plan view conceptually showing the first embodiment of the ventilation type silencer of the present invention.

[0049] Fig.19 This is a front view conceptually showing a second embodiment of the ventilation type silencer of the present invention.

[0050] Fig. 20 It is a plan view conceptually showing the second embodiment of the ventilation type silencer of the present invention.

[0051] Fig.21 This is a graph showing the vorticity in Example 1.

[0052] Fig. 22 This is a graph showing the vorticity in Comparative Example 1.

[0053] Fig.23This is a graph showing the relationship between frequency and transmittance in Example 1.

[0054] Fig.24 This is a graph showing the relationship between frequency and transmission loss in Example 1.

[0055] Fig.25 This is a graph showing the relationship between frequency and transmittance in Comparative Example 1.

[0056] Fig.26 This is a graph showing the relationship between frequency and transmission loss in Comparative Example 1.

[0057] Fig. 27 This is a graph showing the relationship between frequency and transmittance in Comparative Example 2.

[0058] Fig.28 This is a graph showing the relationship between frequency and transmission loss in Comparative Example 2.

[0059] Fig.29 This is a graph showing the relationship between frequency and transmission loss in Examples 1 and 2.

[0060] Fig.30 This is a graph showing the relationship between the permeability and the amount of wind noise in Examples 1 and 2.

[0061] Fig.31 This is a graph showing the relationship between the permeability and the amount of wind noise in Example 3. DETAILED DESCRIPTION

[0062] Hereinafter, the ventilation type silencer of the present invention will be described in detail.

[0063] The description of the constituent elements described below is based on typical embodiments of the present invention, but the present invention is not limited to these embodiments.

[0064] In addition, in this specification, the numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0065] Furthermore, in this specification, "perpendicular" and "parallel" include the error range allowed in the technical field to which the present invention belongs. For example, "perpendicular" and "parallel" mean that the error relative to strict perpendicularity or parallelism is within a range of less than ±10°, and the error relative to strict perpendicularity or parallelism is preferably less than 5°, and more preferably less than 3°.

[0066] In this specification, the terms "same" and "identical" include a range of error generally allowed in the technical field.

[0067] In this specification, the arrangement direction of the inlet side vent pipe, the expansion part and the outlet side vent pipe is defined as the X direction, the first direction orthogonal to the arrangement direction is defined as the Y direction, and the second direction orthogonal to the arrangement direction and the first direction is defined as the Z direction.

[0068] <Ventilation type silencer>

[0069] The ventilation type silencer of the present invention,

[0070] It has: an inlet side vent pipe; an expansion portion, which is connected to the inlet side vent pipe and has a cross-sectional area larger than the cross-sectional area of ​​the inlet side vent pipe; and an outlet side vent pipe, which is connected to the expansion portion and has a cross-sectional area smaller than the cross-sectional area of ​​the expansion portion. The ventilation type silencer has:

[0071] a flow path wall disposed in the expansion portion, communicating with the inlet-side vent pipe and the outlet-side vent pipe, and including a porous sound absorbing member in at least a portion thereof; and

[0072] a back space located on the opposite side of the flow path space in the flow path wall across the flow path wall, and formed by the flow path wall and the frame of the expansion portion;

[0073] The porous sound absorbing member has one or more communication paths that communicate the flow path space with the back side space.

[0074] <Example of implementation>

[0075] The structure of the ventilation type silencer of the present invention will be described using the drawings.

[0076] Figure 1 It is a cross-sectional view conceptually showing an example of an embodiment of the ventilation type silencer of the present invention. Figure 2 yes Figure 1 AA line section view.

[0077] Figure 1 The ventilation type silencer 10 shown has a cylindrical inlet side vent pipe 12 , a flared portion 14 connected to one open end surface of the inlet side vent pipe 12 , and a cylindrical outlet side vent pipe 16 connected to the end surface of the flared portion 14 on the opposite side to the inlet side vent pipe 12 .

[0078] The temperature and humidity of the gas flowing in the vent type silencer 10 differ depending on the method of using the vent type silencer 10. In this example, the gas flowing in the vent type silencer 10 is high temperature and high humidity, and the temperature of the gas is higher than the temperature outside the expansion part 14. Specifically, it is assumed that the temperature range is 20 to 80° C. and the humidity range is 50 to 95% RH.

[0079] [Ventilation tube]

[0080] The inlet-side vent pipe 12 is a cylindrical member that conveys gas flowing in from one opening end surface to the expansion portion 14 connected to the other opening end surface.

[0081] The outlet vent pipe 16 is a cylindrical member that communicates with the expansion portion 14 and conveys gas flowing in from one opening end face connected to the expansion portion 14 to the other opening end face. The cross-sectional area of ​​the outlet vent pipe 16 is smaller than that of the expansion portion 14.

[0082] The cross-sectional shape of the inlet-side vent pipe 12 and the outlet-side vent pipe 16 (hereinafter collectively referred to as vent pipes) may be various shapes such as circular, rectangular, triangular, etc. In addition, the cross-sectional shape of the vent pipe may not be constant in the axial direction of the central axis of the vent pipe. For example, the diameter of the vent pipe may vary in the axial direction.

[0083] The inlet side vent pipe 12 and the outlet side vent pipe 16 may have the same cross-sectional shape and cross-sectional area, or may have different shapes and / or cross-sectional areas. Figure 1 In the illustrated example, the inlet-side vent pipe 12 and the outlet-side vent pipe 16 are arranged so that their central axes coincide with each other, but the present invention is not limited thereto, and the central axis of the inlet-side vent pipe 12 may be offset from the central axis of the outlet-side vent pipe 16 .

[0084] The dimensions (cross-sectional area, etc.) of the inlet-side vent pipe 12 and the outlet-side vent pipe 16 may be appropriately set according to the dimensions of the equipment in which the ventilation type silencer is used, the required ventilation performance, and the like.

[0085] As the forming material of the vent pipe, for example, metal materials, resin materials, reinforced plastic materials and carbon fibers can be cited. As the metal material, for example, aluminum, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, nickel-chromium-molybdenum alloy (nichromemolybdenum) and alloys thereof can be cited. And as the resin material, for example, acrylic resin (PMMA), polymethyl methacrylate, polycarbonate, polyamide-imide, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone, polyethylene terephthalate, polybutylene terephthalate (PBT), polyimide, triacetyl cellulose (TAC), polypropylene (PP), polyethylene (PE), polystyrene (PS), ABS resin (acrylonitrile, butadiene, styrene copolymerized resin), flame retardant ABS resin, ASA resin (acrylonitrile, styrene, acrylate copolymerized resin), PVC (polyvinyl chloride) resin and PLA (polylactic acid) resin can be cited. Furthermore, examples of reinforced plastic materials include carbon fiber reinforced plastics (CFRP: Carbon Fiber Reinforced Plastics) and glass fiber reinforced plastics (GFRP: Glass Fiber Reinforced Plastics).

[0086] [Expansion Department]

[0087] The expansion portion 14 is disposed between the inlet side vent pipe 12 and the outlet side vent pipe 16, communicates with the inlet side vent pipe 12, and conveys the gas flowing in from the inlet side vent pipe 12 to the outlet side vent pipe 16. Figure 1 and Figure 2 In the example shown, the expansion portion 14 has a frame 18 constituting the outer edge of the expansion portion 14. The frame 18 is a hollow substantially rectangular parallelepiped shape extending in the X direction, and the inlet-side vent pipe 12 is connected to one side surface in the X direction, and the outlet-side vent pipe 16 is connected to the other side surface opposite to the one side surface. The central axis of the inlet-side vent pipe 12 is located at the center of one side surface, and the central axis of the outlet-side vent pipe 16 is located at the center of the other opposite side surface.

[0088] The cross-sectional area of ​​the expansion portion 14 perpendicular to the X direction is larger than the cross-sectional area of ​​the inlet-side vent pipe 12, and larger than the cross-sectional area of ​​the outlet-side vent pipe 16. That is, for example, when the cross-sectional shapes of the inlet-side vent pipe 12, the outlet-side vent pipe 16, and the expansion portion 14 are circular, the diameter of the cross section of the expansion portion 14 is larger than the diameters of the inlet-side vent pipe 12 and the outlet-side vent pipe 16.

[0089] The cross-sectional shape of the expansion portion 14 may be various shapes such as a circle, a rectangle, or a triangle. Furthermore, the cross-sectional shape of the expansion portion 14 may not be constant in the axial direction (X direction) of the central axis of the expansion portion 14. For example, the diameter of the expansion portion 14 may vary in the axial direction. Figure 1 In the example shown, the cross section of the expansion portion 14 is set to be rectangular, and the cross-sectional shape is set to be constant in the X direction.

[0090] The dimensions (length, cross-sectional area, etc.) of the expansion portion 14 may be appropriately set according to the dimensions of equipment in which the ventilation type silencer is used, the required silencing performance, and the like.

[0091] As the material for forming the frame 18, similarly to the vent pipe, metal materials, resin materials, reinforced plastic materials, and carbon fibers can be cited. The details of the materials are as described in the description of the vent pipe. Figure 1 In the example shown, the frame body 18 is made of resin.

[0092] The frame 18 is formed by, for example, placing a plurality of Figure 1 In the example shown, six plates are arranged in a box shape, and the plates adjacent to each other are joined by adhesive, bonding agent, solder, welding, etc. Alternatively, when the frame 18 is divided into two parts and fragmented, each fragment can be produced by injection molding and 3D printer, and the fragments can be combined to form the frame 18.

[0093] [Flow path wall]

[0094] A flow path wall 20 is disposed in the expansion portion 14 (more specifically, the frame 18). The flow path wall 20 is disposed so as to allow the inlet-side vent pipe 12 to communicate with the outlet-side vent pipe 16, and to surround the flow path with a region that linearly connects the inlet-side vent pipe 12 and the outlet-side vent pipe 16 as a flow path. The cross section of the flow path space 24 (flow path) surrounded by the flow path wall 20, which is perpendicular to the X direction, is rectangular.

[0095] In this example, the flow direction of the gas flowing in the flow path space 24 coincides with the X direction (the direction in which the inlet-side vent pipes 12 , the expansion portion 14 , and the outlet-side vent pipes 16 are arranged).

[0096] The flow path wall 20 is configured to include a porous sound absorbing member 22 at least in part. Figure 2 As shown in FIG. 1 , the flow path wall 20 is composed of a pair of porous sound absorbing members 22 arranged at a distance in the Z direction and a pair of side walls arranged at a distance in the Y direction as a part of the frame 18. The ends of the porous sound absorbing member 22 in the X direction and the Y direction are in contact with the inner surfaces 18a and 18b of the frame 18, respectively. With this structure, the flow path wall 20 separates the flow path space 24 from the internal space in the frame 18.

[0097] [Back space]

[0098] The back space 30 is located on the side opposite to the flow path space 24 across the flow path wall 20 (hereinafter also referred to as the back side). The back space 30 suppresses the sound waves entering from the flow path space 24 from being reflected by the porous sound absorbing member 22 which is a part of the flow path wall 20 and returning to the flow path space 24 again. That is, if the back side of the porous sound absorbing member 22 is in direct contact with the frame 18, the sound waves entering the porous sound absorbing member 22 from the flow path space 24 are reflected by the frame 18 and return to the flow path space 24. In the ventilated silencer 10, the back space 30 is provided to suppress the sound waves from being reflected and returning to the flow path space 24 again.

[0099] exist Figure 1 In the example shown, the two back spaces are located on both outer sides of the flow path wall 20 in the Z direction. The back space 30 is formed by the flow path wall 20 and the frame 18 of the expansion portion 14. More specifically, Figure 1 and Figure 2 As shown, the back space 30 is surrounded by the outer surface of the flow path wall 20 in the Z direction, i.e., the second surface 22b, the second surface 22b and the surface 18c of the frame 18 opposite in the Z direction, a pair of surfaces 18a of the frame 18 opposite in the X direction, and a pair of surfaces 18b of the frame 18 opposite in the Y direction.

[0100] From the viewpoint of noise reduction performance, the direction perpendicular to the second surface 22b of the flow path wall is Figure 1 In the example shown, the depth of the back space 30 in the Z direction is preferably 10 mm to 400 mm, more preferably 30 mm to 200 mm. In addition, from the viewpoint of sound absorbing performance, the depth of the back space 30 is preferably 2 to 20 times the thickness of the porous sound absorbing member 22, more preferably 3 to 10 times.

[0101] [Porous sound absorbing parts]

[0102] As described above, the porous sound absorbing member 22 is included in a portion of the flow path wall 20. The porous sound absorbing member 22 absorbs sound by converting the sound energy of the sound waves passing through the inside into heat energy. Figure 1 and Figure 2 In the example shown, the entire area of ​​the flow path wall 20 is formed of the porous sound absorbing member 22 .

[0103] like Figure 1 and Figure 2As shown, the porous sound absorbing member 22 is, for example, a plate member that is rectangular in plan view. Among the six surfaces constituting the porous sound absorbing member 22, the widest pair of surfaces are the first surface 22a and the second surface 22b that are opposite to each other in the Z direction. The first surface 22a and the second surface 22b are rectangular surfaces extending in the X direction and the Y direction, respectively. The first surface 22a faces the flow path space 24 and contacts the gas in the flow path space 24. There are no other components between the first surface 22a and the flow path space 24. The second surface 22b faces the back space 30 and contacts the gas in the back space 30. There are no other components between the second surface 22b and the back space 30.

[0104] Four side surfaces of the porous sound absorbing member 22 stand on the four sides forming the outer edge of the first surface 22a, and the four side surfaces are respectively connected to the four sides forming the outer edge of the second surface 22b. Among the four side surfaces, two side surfaces facing each other in the X direction are in contact with the surface 18a of the frame 18 in the X direction, and two side surfaces facing each other in the Y direction are in contact with the surface 18b of the frame 18 in the Y direction.

[0105] The porous sound absorbing member 22 is not particularly limited, and a conventionally known sound absorbing material can be used appropriately. For example, a foam, a foam material (foamed urethane foam (for example, CALMFLEX F of INOAC CORPORATION, polyurethane foam manufactured by HIKARI CO., LTD., Achilles Aeron soft polyurethane foam manufactured by ACHILLES CORPORATION, etc.), soft urethane foam, ceramic particle sintered material, phenolic foam, melamine foam, polyamide foam, etc.), and a non-woven fabric sound absorbing material (ultrafine fiber non-woven fabric (for example, 3M Company Thinsulate, etc.), polyester non-woven fabric (for example, TOKYO BOUON Company White Kyuon, Bridgestone KBG Co., Ltd.'s QonPET, and these products are also provided in a double-layer structure of a thin surface non-woven fabric with high density and a back non-woven fabric with low density) and plastic non-woven fabrics such as acrylic fiber non-woven fabrics, natural fiber non-woven fabrics such as wool and felt, metal non-woven fabrics, and glass non-woven fabrics, etc.), other materials containing tiny air (glass wool, asbestos, nanofiber fiber sound-absorbing materials (silicon dioxide nanofiber, acrylic nanofiber (for example, XAI manufactured by Mitsubishi Chemical Corporation))) and other various well-known sound-absorbing materials.

[0106] Furthermore, a sound absorbing material having a two-layer structure of a thin front nonwoven fabric with high density and a back nonwoven fabric with low density may be used.

[0107] The size and type of the porous sound absorbing member 22 may be appropriately set according to the noise reduction performance (silence reduction frequency, noise reduction amount) required for the ventilation type silencer 10 , the ventilation volume, and the like.

[0108] In the direction perpendicular to the second surface 22b, Figure 1 In the example shown, the thickness of the porous sound absorbing member 22 in the Z direction may be appropriately set to a thickness that can achieve a desired sound absorbing performance, depending on the flow resistance, porosity, labyrinth degree, etc. of the porous sound absorbing member 22. From the viewpoint of sound absorbing performance, the thickness of the porous sound absorbing member 22 in the Z direction is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and most preferably 10 mm to 20 mm.

[0109] [Connecting Road]

[0110] The porous sound absorbing member 22 further includes a communication path 26 that penetrates from the first surface 22 a to the second surface 22 b and connects the flow path space 24 and the back side space 30 .

[0111] like Figure 1 As shown in FIG. 1 , the communication passage 26 is a through hole that penetrates (is connected) perpendicularly to the first surface 22a and is in the shape of a hollow cylinder. The communication passage 26 is a through hole that extends straight without bending, and the central axis of the communication passage 26 has linearity. The inner peripheral surface of the communication passage 26 is formed by the surface of the porous sound absorbing member 22. Figure 1 As shown, the communication path 26 is provided at the center of the first surface 22a, more specifically, at a position where a center line bisecting the first surface 22a in the X direction intersects a center line bisecting the first surface 22a in the Y direction.

[0112] The cross section of the communication passage 26 perpendicular to the communication direction is circular. The opening diameter of the communication passage 26 is preferably 1.0 mm to 50.0 mm, and more preferably 3 mm to 20 mm. In addition, the hole diameter of the plurality of micropores formed in the porous sound absorbing member 22 is usually 100 μm or less, which is different from the opening diameter of the communication passage 26. More specifically, with respect to the minimum value of the opening diameter of 1.0 mm in the communication passage 26, the hole diameter of the micropores in the porous sound absorbing member 22 is less than 1 / 10 of the minimum value of the opening diameter.

[0113] In this example, the communication path 26 is formed as a through hole formed in the porous sound absorbing member 22 in a subsequent step of the molding process, different from the molding process (for example, foam molding) of the porous sound absorbing member 22. However, the present invention is not limited thereto, and the communication path 26 may be formed integrally in the molding process of the porous sound absorbing member 22.

[0114] like Figure 1 and Figure 2As shown, a corner portion 26a is formed at a connection portion between the inner peripheral surface of the communication passage 26 and the first surface 22a. The corner portion 26a extends in a circumferential direction around the central axis of the communication passage 26 and surrounds the communication passage 26.

[0115] [Function and Effect]

[0116] As described above, according to the ventilated silencer 10, the porous sound absorbing member 22 has the communication path 26 that penetrates from the first surface 22a to the second surface 22b and connects the flow path space 24 and the back space 30. Thus, the gas flowing in the flow path space 24 is transported to the back space 30 via the communication path 26. As a result, the back space 30 is less likely to become low temperature and high humidity, and condensation in the back space 30 is suppressed.

[0117] This will be described in more detail using an example assuming that the porous sound absorbing member 22 does not have the communication path 26. As a premise, it is assumed that the temperature in the back space 30 is in a state where it is sufficiently cooled by the air outside the expansion portion 14. When the ventilation type silencer 10 is operated, high-temperature and humid gas flows in the flow path space 24. In the case where the porous sound absorbing member 22 does not have the communication path 26, the gas flowing in the flow path space 24 is blocked by the porous sound absorbing member 22 and does not flow into the back space 30. On the other hand, a plurality of tiny holes are formed in the porous sound absorbing member 22, for example, in the case of sound absorbing urethane, it has a continuous bubble structure, and tiny water vapor passes through, so the humidity of the flow path space 24 is transferred to the back space 30. The heat of the gas flowing in the flow path space 24 is insulated by the porous sound absorbing member 22, so it is not fully transferred to the back space 30. As a result, air supply (forced convection) is not generated in the back space 30 , and the temperature tends to be low and humid, resulting in condensation in the back space 30 .

[0118] In contrast, in the ventilation type silencer 10 which is an example of an embodiment of the present invention, since the porous sound absorbing member 22 has the connecting path 26, the high-temperature gas flowing in the flow path space 24 flows into the back space 30, and the back space 30 is not easily turned into a low-temperature and humid one, thereby suppressing condensation in the back space 30.

[0119] On the other hand, since the porous sound absorbing member 22 has the communication path 26, a corner portion 26a is formed at the connection position between the first surface 22a of the porous sound absorbing member 22 and the inner peripheral surface of the communication path 26. Generally, if a sharp portion such as the corner portion 26a is provided in the flow path space, it contributes to the generation of wind noise and pressure loss, which is not preferable.

[0120] However, according to the ventilated silencer 10 as an example of an embodiment of the present invention, the corner 26a is formed by the porous sound absorbing member 22, so that the gas enters the microscopic holes of the porous sound absorbing member 22 in the corner 26a, thereby reducing the generation of wind noise and pressure loss.

[0121] As described above, according to the ventilation type silencer 10 as an example of the embodiment of the present invention, it is possible to suppress the occurrence of condensation in the rear space 30 and reduce the occurrence of wind noise and pressure loss in the flow path space 24 .

[0122] Furthermore, according to the ventilation type silencer 10 , the opening diameter of the communication path 26 is 1.0 mm to 50 mm, so the gas is sufficiently transported from the flow path space 24 to the rear space 30 .

[0123] Furthermore, according to the ventilation type silencer 10, the permeability of the porous sound absorbing member 22 is preferably 1.0×10 -13 m 2 ~5.0×10 -9 m 2 or 13.0×10 -9 m 2 ~1.0×10 -5 m 2 , and more preferably 1.0×10 -13 m 2 ~4.0×10 -9 m 2 or 15.0×10 -9 m 2 ~1.0×10 -5 m 2 As a result, the gas effectively enters the micropores of the porous sound absorbing member 22 at the corner 26a and its surroundings, further reducing the generation of wind noise and pressure loss. In particular, by setting the permeability to 1.0×10 -13 m 2 The above results in reducing the wind noise. By setting the permeability to 1.0×10 -5 m 2 Next, the pressure loss is reduced.

[0124] In addition, the permeability is given by K = Q × μ × L / (ΔP × A). Here, the permeability is K (m 2 ), the flow rate Q(m 3 / s), the length of the flow path is L (m), and the cross-sectional area of ​​the flow path is A (m 2 ), the pressure difference is set to ΔP (Pa), and the viscosity is set to μ (Pa·s).

[0125] When measuring the permeability of a porous sound absorbing member (sound absorbing material), first, air pressure is applied to the sound absorbing material and the flow rate that penetrates the sound absorbing material is measured to measure the permeability. The method for measuring the permeability is standardized as "ASTM D737-Air Permeability of Textile Fabrics" or ISO 9237.

[0126] Therefore, it is possible to perform the measurement using an air permeability tester conforming to these standards.

[0127] These measuring methods can measure the permeability by applying air with increased pressure to the sound absorbing material like an air permeability tester or air permeation tester and measuring the pressure and the flow rate of the penetrating air. As such a tester, "YG461E" from Ningbo Textile Instrument Factory can be cited.

[0128] Alternatively, the permeability can be determined by numerically calculating the air flowing through the structure acquired by SEM or X-ray CT scanning using fluid calculations such as the CFD module of COMSOL, and calculating the applied pressure and outflow rate.

[0129] In addition, the permeability of the porous sound absorbing member can be obtained by referring to the following literature.

[0130] https: / / www.comsol.com / blogs / computing-porosity-and-permeability-in-porous-media-with-a-submodel /

[0131] Furthermore, according to the ventilation type silencer 10, the above-mentioned effect is more preferably exerted when the frame 18 of the expansion part 14 is made of resin. When the frame 18 of the expansion part 14 is made of resin, since the thermal conductivity of the resin is small, the heat of the flow path space 24 is not easily transferred to the back space 30 via the frame 18, so the back space 30 is prone to become low temperature and high humidity, causing condensation. In contrast, in the ventilation type silencer of the present invention, even if the frame 18 of the expansion part 14 is made of resin, the heat of the flow path space 24 is transferred to the back space 30 by the gas through the connecting path 26, so the generation of condensation in the back space 30 can be suppressed. Moreover, compared with a metal frame, the resin frame 18 has a large degree of design freedom (degree of freedom of shape) by, for example, injection molding or 3D printing, and is inexpensive.

[0132] Furthermore, according to the ventilation type silencer 10 , as shown in this example, when the temperature of the gas flowing in the flow path space 24 is higher than the temperature outside the expansion portion 14 , the effect of the present invention can be further exerted.

[0133] Furthermore, according to the ventilation type silencer 10, since the communication passage 26 is a through hole, it can be easily processed.

[0134] <Another Example of Embodiment>

[0135] An example of an embodiment of the present invention related to the ventilation type silencer is described above, but the above embodiment is only an example for facilitating the understanding of the present invention and does not limit the present invention. That is, the present invention can be changed and improved within the scope of its purpose. Moreover, the present invention of course includes its equivalents.

[0136] [Modification 1]

[0137] For reference Figure 3 to Figure 5 , a ventilation type silencer 100 as another example of the embodiment of the present invention will be described. Figure 3 This is a cross-sectional view conceptually showing another example of the ventilation type silencer of the present invention. Figure 4 It is conceptually expressed Figure 3 A three-dimensional view of a ventilation type silencer. Figure 5 yes Figure 4 In the following description, aspects different from the above-described example of the embodiment will be described, and description of overlapping aspects will be omitted.

[0138] (Ventilation tube)

[0139] like Figure 3 As shown, the inlet-side vent pipe 112 and the outlet-side vent pipe 116 have their central axes deviated from the central position of the expansion portion 114 in the Z direction ( Figure 3 In this example, Figure 4 As shown, the inlet-side vent pipe 112 and the outlet-side vent pipe 116 have rectangular cross sections.

[0140] (Flow path wall)

[0141] like Figure 3 to Figure 5As shown in FIG. 1 , the flow path wall 120 is composed of three porous sound absorbing members 122 and a part of the frame 118 (here, the bottom wall). More specifically, the flow path wall 120 is composed of a pair of porous sound absorbing members 122 arranged at intervals in the Y direction and the bottom wall of the frame 118 and the porous sound absorbing member 122 arranged at intervals in the Z direction. In other words, a pair of porous sound absorbing members 122 facing each other in the Y direction are arranged on the bottom wall of the frame 118, and the ends of the pair of porous sound absorbing members 122 on the side opposite to the bottom wall of the frame 118 are connected to the porous sound absorbing members 122 facing the bottom wall of the frame 118 in the Z direction. The ends of the three porous sound absorbing members 122 in the X direction are in contact with the inner surface 118a of the frame 118. With this structure, the flow path wall 120 separates the flow path space 124 from the internal space in the frame 118.

[0142] The cross section of the flow path space 124 in the flow path wall 120 perpendicular to the X direction is rectangular. The inner surface of the flow path space 124 is composed of four surfaces, which are composed of the first surfaces 122a of the three porous sound absorbing members 122 and the surface 118c of the frame 118. More specifically, the inner surface of the flow path space 124 is composed of the first surfaces 122a of the porous sound absorbing members 122 and the surface 118c of the frame 118 facing each other in the Z direction, and the first surfaces 122a of a pair of porous sound absorbing members 122 facing each other in the Y direction.

[0143] (Back space)

[0144] The back space 130 is located on the back side of the three porous sound absorbing members 22. The back space 130 is configured to surround the three porous sound absorbing members 122, and more specifically, is surrounded by the second surface 122b on the outside (back space 130 side) of the three porous sound absorbing members 122 and the surfaces 118a, 118b, and 118c of the frame 118.

[0145] (Connecting Road)

[0146] like Figure 4 As shown, communication paths 126 and 128 are formed on three first surfaces 122a of the porous sound absorbing member 122 constituting the inner surface of the flow path space 124. The communication paths 126 and 128 penetrate from the first surface 122a to the second surface 122b, respectively, and connect the flow path space 124 and the back space 130.

[0147] More specifically, on one side ( Figure 3A plurality of (two in this example) communication paths 126 are provided on the porous sound absorbing member 122 (on the upper side in the middle). The two communication paths 126 are provided on the first surface 122a at intervals along the flow direction (X direction) of the gas flowing in the flow path space 124. The communication path 26 is provided at the center of the first surface 122a in the Y direction. The cross section of the communication path 126 perpendicular to the communication direction (Z direction) is a circular through hole. The details of the structure of the communication path 126 are the same as the communication path 26 shown in the above embodiment, so the description is omitted.

[0148] A corner portion 126a is formed at a connection portion between the inner peripheral surface of the communication passage 126 and the first surface 122a. The corner portion 126a extends in a circumferential direction around the central axis of the communication passage 126 and surrounds the communication passage 126.

[0149] A plurality of (two in this example) communication paths 128 are formed on each of the pair of porous sound absorbing members 122 arranged at intervals in the Y direction. The two communication paths 128 are provided at intervals along the flow direction (X direction) of the gas flowing in the flow path space 124. The communication path 128 is formed by cutting off one end of the porous sound absorbing member 122, more specifically, one end of the bottom wall side of the frame 118 in the Z direction.

[0150] The communication passage 128 is provided in contact with the surface 118c of the frame 118 (bottom wall). The inner surface of the communication passage 128 is composed of four surfaces, a pair of surfaces of the porous sound absorbing member 122 facing each other in the X direction, and surfaces of the porous sound absorbing member 122 and the surface 118c of the frame 118 facing each other in the Z direction. Figure 3 As shown, the communication path 128 penetrates (communicates) perpendicularly to the first surface 122a. The communication path 128 is a rectangular hole in a hollow cuboid shape, and the cross section perpendicular to the communication direction (Y direction) is rectangular. The communication path 128 can also be said to be a notch with a rectangular cross section.

[0151] The opening diameter of the equivalent circle of the communication path 128 is preferably 1.0 mm to 50 mm, and more preferably 3 mm to 20 mm. The "equivalent circle" means that a shape other than a circle is virtually replaced with a circle according to the opening area.

[0152] The total opening area of ​​the communication paths 126 and 128 is preferably 20 mm. 2 More preferably, 20 to 2000 mm 2 , more preferably 30 to 500 mm 2Here, the target is the opening area of ​​all the communication passages 126 and 128 communicating with one back space 130. Therefore, in this example, it refers to the total value of all the opening areas of the two communication passages 126 and the four communication passages 128 communicating with one back space 130.

[0153] In addition, the “opening area” refers to the area of ​​a position where the opening area is the smallest when the diameter of the communication path 26 changes in the communication direction.

[0154] In this example, the communication path 128 is formed as a notch in the porous sound absorbing member 122 in a subsequent step of the molding process, different from the molding process (for example, foam molding) of the porous sound absorbing member 122. However, the present invention is not limited thereto, and the communication path 128 may be formed integrally in the molding process of the porous sound absorbing member 122.

[0155] A corner portion 128a is formed at a connection portion between the inner surface of the communication passage 128 and the first surface 22a. The corner portion 128a extends in a circumferential direction around the central axis of the communication passage 128 and surrounds the communication passage 128.

[0156] (Dust filter)

[0157] like Figure 5 As shown, dust filters 132 are arranged in the communication paths 126 and 128. The dust filters 132 prevent dust and the like from entering the back space 130 from the flow path space 124. The dust filters 132 are, for example, metal meshes, and in order to avoid an increase in pressure loss in the flow path space 24, the opening ratio of the dust filters 132 is preferably, for example, 20 to 95%.

[0158] In this example, the dust filter 132 is disposed at the end of the communication passages 126 and 128 on the second surface 122b side. In order to suppress the generation of wind noise and pressure loss in the flow path space 24, the dust filter 132 is preferably not disposed at the corners 126a and 128a (the end of the communication passages 126 and 128 on the first surface 122a side).

[0159] (Function and Effect)

[0160] As described above, according to the ventilation type silencer 100, when the opening areas of the plurality of communication paths 126 and 128 are added together, the total area is 20 mm. 2 As described above, the gas is sufficiently transported from the flow path space 124 to the back side space 130 .

[0161] Furthermore, according to the ventilation type silencer 100, the plurality of communication paths 126 and 128 are provided at intervals along the flow direction (X direction) of the gas flowing in the flow path space 124. Thus, in the communication paths 126 and 128 on the upstream side of the flow direction, the gas flows from the flow path space 124 to the back space 130, and in the communication paths 126 and 128 on the downstream side of the flow direction, the gas flows from the back space 130 to the flow path space 124. In this way, the gas in the flow path space 124 smoothly enters and exits the back space 130, and thus the generation of condensation in the back space is further suppressed.

[0162] Furthermore, according to the ventilation type silencer 100 , since the dust filter 132 is disposed on the communication paths 126 and 128 , the intrusion of dust and the like into the rear space 130 can be reduced.

[0163] Furthermore, according to the ventilation type silencer 100, the inner surface of the flow path space 124 is composed of the first surface 122a of the porous sound absorbing member 122 and the surface 118c of the frame 118, and the frame 118 can be used as a part of the flow path space 124. According to the above structure, the degree of freedom of arrangement of the flow path space 124 in the frame 118 can be improved. Furthermore, in the above structure, the gas in the flow path space 124 contacts the surface 118c of the frame 118, so that compared with the case where the inner surface of the flow path space 124 is entirely composed of the surface of the porous sound absorbing member 122, the heat of the gas in the flow path space 124 can be transferred to the back space 130 via the frame 118. As a result, the generation of condensation in the back space 130 can be further suppressed.

[0164] Furthermore, since the communication passage 128 is provided in contact with the surface 118c of the frame 118, the flow resistance of the inner surface of the communication passage 128 can be reduced compared to the case where the inner surface of the communication passage 128 is entirely formed by the surface of the porous sound absorbing member 122. As a result, the gas is smoothly transported from the flow passage space 124 to the back space 130, and the generation of condensation in the back space 130 can be further suppressed.

[0165] Furthermore, according to the ventilated silencer 100, the communication paths 126 and 128 are respectively formed on the three first surfaces 122a of the porous sound absorbing member 122 constituting the inner surface of the flow path space 124. Thus, the number of the communication paths 126 and 128 is ensured, and the gas is smoothly transported from the flow path space 124 to the back space 130. As a result, the generation of condensation in the back space 130 can be further suppressed.

[0166] [Modification 2]

[0167] According to the ventilation type silencer 10 shown in the above embodiment, the flow direction of the gas flowing in the flow path space 24 is consistent with the X direction (the arrangement direction of the inlet side vent pipe 12, the expansion part 14 and the outlet side vent pipe 16), but it is not limited to this. The flow direction may also be different from the X direction.

[0168] For example, Figure 6 In the ventilation type silencer 200A shown in the figure, the central axis of the inlet side vent pipe 212 can be located on one side ( Figure 6 The central axis of the outlet side vent pipe 216 may also be located closer to the other side (the upper side) than the central position of the expansion portion 214 in the Z direction. Figure 6 In this case, the flow path wall 220 is connected to the inlet side vent pipe 212 and the outlet side vent pipe 216, and the flow path space 224 extends from one side of the Z direction to the other side ( Figure 6 The lower side of the Figure 6 As shown, the back space 230 may be a hollow triangular prism extending in the Y direction due to the inclination of the flow path wall 220 , and the communication path 226 may be a through hole that penetrates the first surface 222 a of the porous sound absorbing member 222 at an inclination.

[0169] [Variation 3]

[0170] Next, refer to Figure 7 and Figure 8 Next, a ventilation type silencer 200B as another example of an embodiment of the present invention will be described. Figure 7 This is a perspective view conceptually showing another example of the ventilation type silencer of the present invention. Figure 8 yes Figure 7 In addition, Figure 7 In the figure, a part of the wall constituting the inlet side vent pipe 212, the outlet side vent pipe 216 and the frame 218 is not shown. Specifically, a part of the wall constituting the frame 218 refers to the side wall on the inlet side vent pipe 212 side in the X direction and the upper wall located above in the Z direction.

[0171] In the ventilation type silencer 200B, as Figure 7 As shown, the central axis of the inlet side vent pipe 212 is located on one side of the center position of the expansion portion 214 in the Y direction, and the central axis of the outlet side vent pipe 216 is located on the other side of the center position of the expansion portion 214 in the Y direction. Thus, the flow path space 224 is inclined from one side of the Y direction to the other side as it moves toward the X direction.

[0172] like Figure 7As shown, the flow path wall 220 is composed of two inner walls 227 constituting the side walls, a porous sound absorbing member 222 constituting the upper wall, and a part (bottom wall) of the frame 218 constituting the lower wall. More specifically, the flow path wall 220 is composed of a pair of inner walls 227 arranged at intervals in a direction perpendicular to the flow direction of the gas flowing in the flow path space 224, and a porous sound absorbing member 222 and a part of the frame 218 arranged at intervals in the Z direction.

[0173] In this example, the inner wall 227 is, for example, a non-porous metal plate having no micropores. Figure 7 As shown, it is rectangular when viewed from the side.

[0174] like Figure 7 As shown in FIG. 1 , the porous sound absorbing member 222 constituting the upper wall of the flow path wall 220 is a plate member extending along the flow direction of the gas. The two ends of the porous sound absorbing member 222 in the flow direction are in contact with a pair of side walls of the frame 218 that are opposite to each other in the X direction. In addition, the end (side surface) in the direction orthogonal to the flow direction of the porous sound absorbing member 222 extends to the side surfaces of the outer sides of the pair of inner walls 227. The upper surface of the porous sound absorbing member 222 is in contact with the inner wall 227. Figure 7 The upper wall of the frame 118 (not shown) is in contact.

[0175] like Figure 7 As shown, the bottom surface of the porous sound absorbing member 222 is the first surface 222a in contact with the gas in the flow path space 224 , and the side surface of the porous sound absorbing member 222 in the direction perpendicular to the flow direction is the second surface 222b in contact with the gas in the back space 230 .

[0176] like Figure 7 and Figure 8 As shown, there is a back space 230 on the back of each of the two inner walls 227. Figure 7 As shown, the back space 230 is a triangular prism-shaped space extending in the Z direction.

[0177] The porous sound absorbing member 222 has a plurality of (four in this example) communication paths 226 that penetrate from the first surface 222 a to the second surface 222 b and connect the flow path space 224 and the back side space 230 .

[0178] More specifically, the communication path 226 is formed by cutting off the lower end of the second surface 222b of the porous sound absorbing member 222. Figure 8 As shown in FIG. 2 , the communication passage 226 extends from the second surface 222b across the inner wall 227 to the flow path space 224. The communication passage 226 is a recessed portion (depressed portion) opened on the flow path space 224 side in the Z direction. Figure 8As shown, the open end of the communication passage 226 is covered by the inner wall 227 except for the region facing the flow passage space 224. The flow passage space 224 and the back side space 230 are communicated with each other through the communication passage 226 configured in this way.

[0179] The four communication paths 226 are arranged at intervals along the flow direction of the gas flowing in the flow path space 224. More specifically, Figure 8 As shown, two communication paths 226 are provided on both sides of the flow path space 224 on the upstream side in the flow direction, and two communication paths 226 are provided on both sides of the flow path space 224 on the downstream side in the flow direction of the gas flowing in the flow path space 124.

[0180] The two connecting passages 226 located on the upstream side extend obliquely relative to the flow direction so as to approach the back space 230 from the flow passage space 224 as they advance toward the downstream side. As a result, the gas flowing from the inlet side vent pipe 212 flows smoothly into the connecting passages 226, and the gas is smoothly transported from the flow passage space 224 to the back space 230. In particular, the connecting passage 226 ( Figure 8 The lower communication passage 226 of the inlet side extends substantially parallel to the flow direction (X direction) of the a gas flowing in the inlet side vent pipe 212. Therefore, the gas flowing from the inlet side vent pipe 212 flows smoothly into the communication passage 226.

[0181] The two connecting passages 226 located on the downstream side extend obliquely relative to the flow direction so as to approach the flow passage space 224 from the back space 230 as they advance toward the downstream side. As a result, the gas flows smoothly from the back space 230 into the connecting passages 226, and the gas smoothly returns from the back space 230 to the flow passage space 224. In particular, the connecting passage 226 ( Figure 8 The upper communication passage 226 of the outlet side extends substantially parallel to the flow direction (X direction) of the gas flowing in the outlet side vent pipe 216. Therefore, the gas flowing from the communication passage 226 flows out to the outlet side vent pipe 216 smoothly.

[0182] In addition, Figure 7 and Figure 8 In the ventilation type silencer 200B shown in FIG. 1 , the end (side surface) in the direction perpendicular to the flow direction of the porous sound absorbing member 222 is extended to the side surfaces of the outer sides of the pair of inner walls 227. However, this is not limited to this. For example, Fig. 9 and Fig.10In the ventilation type silencer 200C shown, the porous sound absorbing member 222 can fill the upper space of the frame 118. That is, the four side surfaces of the porous sound absorbing member 222 can respectively contact the four side walls of the frame 218. The upper surface of the porous sound absorbing member 222 contacts the upper wall of the frame 118.

[0183] In this case, the communication path 226 is provided on the lower surface of the porous sound absorbing member 222. Fig.10 As shown in FIG. 1 , the flow path space 224 and the back space 230 in the Z direction are opened to form a concave portion (depressed portion). The communication path 226 extends from the flow path space 224 to the back space 230 across the inner wall 227. The opened end of the communication path 226 is as shown in FIG. Fig.10 As shown, except for the region facing the flow path space 224 and the back side space 230, it is covered by the inner wall 227. The flow path space 224 and the back side space 230 can be communicated through the communication path 226 configured in this way.

[0184] And, in Figure 7 and Figure 8 In the ventilation type silencer 200B shown in the figure, the inner wall 227 is made of a non-porous metal plate without micropores, but it can also be a porous sound absorbing member. Fig.11 As in the ventilation type silencer 200D shown in the figure, a part of the inner wall 227, specifically, the central area in the Y direction, may be replaced with a porous sound absorbing member 228. Fig.11 and Figure 7 Similarly, the inlet side vent pipe 212, the outlet side vent pipe 216, and a portion of the wall constituting the frame 218 are not shown, and one side of a pair of side walls facing each other in the Y direction of the frame 218 ( Fig.11 in front of the camera).

[0185] The porous sound absorbing member 228 included in the inner wall 227 is a rectangular plate member extending in the Z direction from the porous sound absorbing member 222 constituting the upper wall of the flow path wall 220 to the bottom wall of the frame body 218 and having the Z direction as the long side.

[0186] The porous sound absorbing member 228 is provided with a communication path 228a which is formed by cutting off the lower end of the porous sound absorbing member 228 in the Z direction. The communication path 228a penetrates the porous sound absorbing member 228 to connect the flow path space 224 and the back side space 230. Fig.11 As shown, the cross section of the communication path 228a perpendicular to the communication direction is rectangular.

[0187] In addition, the communication path 228a may be provided by cutting off the upper end in the Z direction, or may be provided at both the upper end and the lower end, or may be provided at the center in the Z direction, or may be provided at any position of the porous sound absorbing member 228. Fig.11In the example shown in FIG. 2 , the cross section of the communication path 228 a perpendicular to the communication direction is rectangular, but the present invention is not limited thereto and may be various shapes such as a circular shape or a triangular shape.

[0188] [Modification (Other)]

[0189] In the ventilation type silencer 10 shown in the example of the above embodiment, the communication passage 26 (see Figure 1 and Figure 2 ) is a circular cross section perpendicular to the penetration direction, but is not limited thereto and may be a rectangular, triangular or other shape. Fig.12 As shown, it can be an elliptical shape or as Fig.13 As shown, it is rectangular.

[0190] Furthermore, in the ventilation type silencer 10 shown in one example of the above-mentioned embodiment, as Figure 1 As shown in FIG. 1 , the communication path 26 is provided at the center of the first surface 22a, but is not limited thereto. Fig.14 As shown, the communication paths 26 may be disposed at both ends of the porous sound absorbing member 22 in a direction perpendicular to the flow direction of the gas.

[0191] Furthermore, in the ventilation type silencer 10 shown in the example of the above embodiment, the communication path 26 is a through hole that penetrates perpendicularly to the first surface 22a, but the present invention is not limited thereto and the communication path 26 may penetrate obliquely to the first surface 22a.

[0192] For example, Fig.15 As shown in FIG. 1 , the communication passage 26 may penetrate the porous sound absorbing member 22 obliquely toward the flow direction of the gas relative to the side surface of the porous sound absorbing member 22. In particular, as shown in FIG. Fig.16 As shown in the figure, in the two communication passages 26 provided at a distance along the flow direction of the gas, the direction of penetration in each communication passage 26 may be changed. That is, the communication passage 26 on the upstream side may be inclined relative to the flow direction and penetrate the porous sound absorbing member 22 in such a manner that the passage space approaches the back space as it advances toward the downstream side. The communication passage 26 on the downstream side may be inclined relative to the flow direction and penetrate the porous sound absorbing member 22 in such a manner that the passage space approaches the passage space as it advances toward the downstream side. In other words, the communication passage 26 may be provided at an angle relative to the porous sound absorbing member 22 so that the gas can easily flow into the passage space and easily flow out from the back space.

[0193] Furthermore, the cross section of the communication passage 26 perpendicular to the penetration direction is circular, but the cross section of the communication passage 26 may not be constant in the communication direction of the communication passage 26. For example, the diameter of the communication passage 26 may vary in the communication direction, and the communication passage 26 may be tapered along the communication direction.

[0194] Furthermore, the number of the communication paths 26 is not limited to one or two, and the porous sound absorbing member 22 may have a plurality (three or more) of communication paths 26 .

[0195] In the ventilation type silencer 10 shown in the example of the above embodiment, the communication path 26 is provided in a pair of porous sound absorbing members 22 (see FIG. 1 ) which are arranged at intervals in the Z direction of the upper wall and the lower wall constituting the flow path wall 20. Figure 1 and Figure 2 However, the communication path is not limited thereto, and the communication path may be provided in any region of the porous sound absorbing member constituting the flow path wall in any shape. Figure 12 to Figure 16 The porous sound absorbing member shown is arranged in any area of ​​the flow path wall.

[0196] Furthermore, in the ventilation type silencer 10 shown in the example of the above embodiment, the flow path wall 20 is configured to include two porous sound absorbing members 22 (see Figure 1 and Figure 2 ), but is not limited thereto, for example, the flow path wall may include one porous sound absorbing member, and the other parts are composed of a frame. In the following embodiments, the flow path wall is composed of one porous sound absorbing member and a frame.

[0197] Example

[0198] Below, based on embodiment, the present invention is further described in detail.As long as the material, usage amount, ratio, processing content, processing step etc. shown in the following embodiment do not depart from the purpose of the present invention, then can be appropriately changed.Thereby, the scope of the present invention should not be interpreted restrictively by the embodiment shown below.

[0199] [Example 1]

[0200] like Fig.17 and Fig.18 As shown in FIG. 1 , a ventilation type silencer 300 a is manufactured in which a porous sound absorbing member 322 is arranged in the expansion portion 314 . Fig.17 1 is a front view conceptually showing the first embodiment of the ventilation type silencer of the present invention. Fig.18 It is a plan view conceptually showing the first embodiment of the ventilation type silencer of the present invention.

[0201] The inlet side vent pipe 312 and the outlet side vent pipe 316 are connected to the front and rear of the expansion part 314 in the X direction, and the inlet side vent pipe 312, the flow path space 324 of the expansion part 314 and the outlet side vent pipe 316 are formed by a long cylindrical conduit. The cylindrical conduit uses a conduit with a rectangular cross section perpendicular to the X direction and an inner dimension of the cross section of 25 mm in the Y direction × 25 mm in the Z direction. A box-shaped silencer with an open surface on the side of the cylindrical conduit and an inner dimension of 100 mm in the X direction × 25 mm in the Y direction × 40 mm in the Z direction is installed in the center of the cylindrical conduit in the X direction.

[0202] A porous sound absorbing member 322 (foamed polyurethane foam, CALMFLEX F-2 manufactured by INOAC CORPORATION) with a size of 100 mm in the X direction, 25 mm in the Y direction, and 10 mm in the Z direction (thickness direction) was arranged at the end of the cylindrical duct side of the silencer. The permeability of the porous sound absorbing member 322 was 3.5×10 -9 m 2 .

[0203] A communication path 326 a of 20 mm in the X direction and 25 m in the Y direction is provided at the center of the porous sound absorbing member 322 in the X direction so that the flow path space 324 and the back side space 330 communicate with each other.

[0204] [Example 2]

[0205] In place of the communication path 326a, two communication paths 326b whose dimensions in the X direction were reduced to 10 mm were arranged in the X direction. A ventilation type silencer 300b (reference Fig.19 and Fig. 20 ).

[0206] [Example 3]

[0207] A ventilation type silencer (not shown) having the same structure as that of Example 1 was produced except that a communication path whose dimension in the X direction was enlarged to 40 mm was provided in place of the communication path 326 a .

[0208] [Comparative Example 1]

[0209] A ventilation type silencer (not shown) having the same structure as that of Example 1 was produced except that a non-porous plate having the same size as that of the porous sound absorbing member 322 was arranged in place of the porous sound absorbing member 322. As in Example 1, a connecting passage of 20 mm in the X direction and 25 mm in the Y direction was provided in the center of the non-porous plate so that the flow path space 324 and the back space 330 were connected.

[0210] [Comparative Example 2]

[0211] A ventilation type silencer (not shown) having the same structure as that of Example 1 was produced except that the communication path 326a was not provided in the center of the porous sound absorbing member 322. That is, the flow path space and the back side space were not connected through the communication path.

[0212] [Comparative Example 3]

[0213] A ventilation type silencer (not shown) having the same structure as that of Comparative Example 1 was produced except that the dimension of the communication path in the X direction was enlarged to 40 mm.

[0214] [evaluate]

[0215] (Vorticity)

[0216] like Fig.21 and Fig. 22 As shown in FIG. 1 , regarding the ventilated silencers of Example 1 and Comparative Example 1 produced, the vorticity around the communication passage was measured. Fig.21 represents the vorticity in Example 1, Fig. 22 represents the vorticity in Comparative Example 1. Fig.21 and Fig. 22 The results show that, in the corners (edges) of the connecting passage, vortices are generated in Comparative Example 1 (large vorticity), but the generation of vortices is reduced in Example 1 compared with the Comparative Example (small vorticity). It is speculated that in Example 1, the gas enters the tiny holes of the porous sound absorbing member 322, thereby reducing the generation of vortices.

[0217] (Condensation)

[0218] Condensation was measured for the ventilated silencers of Examples 1 and 2 and Comparative Examples 1 and 2 produced.

[0219] Condensation was measured by visually checking the back space and measuring the weight difference of the vent type silencer before and after the evaluation.

[0220] As a procedure, the weight of the ventilation type silencer before evaluation is first measured. Then, the ventilation type silencer is arranged in an insulation box (expanded polystyrene box), and the environment in the insulation box is adjusted to 7°C to adapt the ventilation type silencer to the ambient temperature. Then, air is allowed to flow into the ventilation type silencer. The wind speed of the air is set to 10m / s or 20m / s, the temperature is set to 33°C, and the humidity is set to 65%RH. After the air flow is continued for about 12 hours, the air flow is stopped, and after leaving it for about 30 minutes, the weight of the ventilation type silencer is measured.

[0221] As a result of the evaluation, condensation did not occur in the ventilation type silencers of Examples 1 and 2 and Comparative Example 1, but condensation occurred in Comparative Example 2. When the back space of Comparative Example 2 was visually confirmed, visible moisture content was generated in the back space. It is speculated that in Comparative Example 2, since no communication path was provided, air in the flow path space did not flow into the back space, resulting in condensation.

[0222] (Transmittance and transmission loss)

[0223] The transmittance and transmission loss of the produced ventilated silencers of Examples 1 and 2 and Comparative Examples 1 and 2 were measured. The measurement was performed by a four-terminal method using an acoustic tube.

[0224] The measurement results of transmittance and transmission loss of Example 1, Comparative Examples 1 and 2 are shown in Figure 23 to Figure 28 .exist Figure 23 to Figure 28 In the graph of , the horizontal axis represents frequency and the vertical axis represents transmittance or transmission loss. Fig.23 and Fig.25 By comparison, it can be seen that Example 1 exhibits a sound absorbing effect in a wider frequency band than Comparative Example 1. It is presumed that in Comparative Example 1, since a non-porous plate of the same size is arranged instead of a porous sound absorbing member, it functions as a Helmholtz resonator, and thus the sound absorbing effect is small except for the resonance frequency.

[0225] And, if Fig.24 and Fig.28 By comparison, it can be seen that Example 1 shows an excellent sound-absorbing effect in the resonance characteristics, especially in the low-frequency side (for example, around 2kHz), compared with Comparative Example 2. It is speculated that in Example 1, since the porous sound absorbing member has a connecting path, in addition to the sound absorbing effect based on the porous sound absorbing member, the connecting path and the back space act as a Helmholtz resonator and resonate around 2kHz, thereby also obtaining a sound absorbing effect based on resonance. On the other hand, Comparative Example 2 is composed of a porous sound absorbing member without a connecting path, so that no resonance is generated in the back space, and only the sound absorbing effect based on the porous sound absorbing member is used.

[0226] Next, the transmission loss measurement results of Example 2 are compared with those of Example 1 and are shown in Fig.29 .exist Fig.29 In the graph of , the horizontal axis represents frequency and the vertical axis represents transmission loss. The dotted line in the graph represents Example 1, and the solid line represents Example 2. Fig.29 As shown, it can be seen that Example 2 exhibits the same noise cancellation effect as Example 1 except for the frequency band of the resonance frequency (for example, 2 kHz). In other words, compared with Example 1, Example 2 is inferior in the noise cancellation effect in the frequency band of the resonance frequency.

[0227] On the other hand, if we refer to Fig.28 , it can be said that the noise reduction effect of Example 2 is equal to or better than that of Comparative Example 2 (a porous sound absorbing member without a connecting path) in the frequency band at the resonant frequency. For example, at a frequency of 2kHz, the transmission loss of Example 2 is about 17dB (reference Fig.29 ), in contrast, the transmission loss of Comparative Example 2 is about 16 dB (reference Fig.28 ). That is, it can be seen that Example 2 has a smaller noise reduction effect than Example 1 in the frequency band of the resonance frequency, but has a noise reduction effect equal to or greater than that of Comparative Example 2 which is composed of a porous sound absorbing member without a communication path.

[0228] (Wind noise amount)

[0229] The wind noise of the ventilated silencers of Examples 1 and 2 and Comparative Examples 1 and 2 thus produced was measured.

[0230] As a procedure, first, air at 20 m / s is flowed into the ventilation type silencer. At this time, a silencer box filled with sound absorbing material is connected between the air supply fan and the ventilation type silencer so that the sound of the air supply fan located on the upstream side of the flow direction of the ventilation type silencer and used to supply air to the ventilation type silencer does not affect the measurement, and the air supply sound caused by the air supply fan is eliminated.

[0231] The downstream side of the outlet side vent pipe was connected to a reverberation chamber, and the amount of wind noise generated by the vent type silencer was measured. At this time, a microphone was placed in the reverberation chamber at a position where it would not directly contact the air flowing out of the vent type silencer.

[0232] The wind noise levels of Examples 1 and 2 and Comparative Examples 1 and 2 are 40 dBA for Example 1, 39 dBA for Example 2, 45 dBA for Comparative Example 1, and 39 dBA for Comparative Example 2.

[0233] It can be seen that the wind noise level of Example 1 is 5dB lower than that of Comparative Example 1, and the wind noise level is 1dB higher than that of Comparative Example 2. Almost all people can usually recognize the volume difference when the difference in wind noise level is 3dB or more. Therefore, from the results of Example 1 and Comparative Example 1, it can be seen that people can easily recognize the reduction in wind noise level caused by changing from a non-porous plate to a porous sound absorbing member. On the other hand, from the results of Example 1 and Comparative Example 2, it can be seen that it is difficult for people to recognize the increase in wind noise level caused by the provision of a connecting path.

[0234] It can be seen that Example 2 is 39 dB, which is equivalent to Comparative Example 2, and that the wind noise level can be maintained equivalent to that of Comparative Example 2 which is composed of a porous sound absorbing member without a communication path.

[0235] (Permeability)

[0236] The change in the amount of wind noise relative to the permeability of the porous sound absorbing member was estimated by simulation.

[0237] The permeability is obtained by numerically calculating the air flowing through the structure acquired in SEM or X-ray CT scans using fluid calculations such as COMSOL's CFD module, and calculating the applied pressure and outflow rate.

[0238] Fig.30 Graph showing the relationship between the permeability and the wind noise level in Examples 1 and 2. The horizontal axis of the graph shows the permeability, and the vertical axis shows the wind noise level of Examples 1 and 2 relative to Comparative Example 1. The dotted line in the graph shows Example 1, and the solid line shows Example 2.

[0239] The simulation results show that, for Example 1, at a permeability of 7.5×10 -9 m 2 When the wind noise level is the smallest relative to Comparative Example 1, the wind noise level is the smallest. As described above, the case where almost everyone can usually recognize the volume difference is called the case where the wind noise level difference is open by 3 dB or more. From this inference result, it can be seen that if the permeability is 5.0×10 -9 m 2 Below or 13.0×10 -9 m 2 As shown above, Example 1 is more than 3dB smaller than Comparative Example 1.

[0240] It can be seen that the wind noise amount of Example 2 is smaller than that of Example 1 in all permeability ranges. In particular, it is known that the peak wind noise amount is greater than 7.5×10 -9 m 2 On one side, the amount of wind noise is less than that in Example 1.

[0241] Fig.31 : is a graph showing the relationship between the permeability and the wind noise amount in Example 3. The horizontal axis of the graph represents the permeability, and the vertical axis represents the wind noise amount of Example 3 relative to Comparative Example 3. As described above, Fig.31 The results are for a communication path with a dimension in the X direction enlarged to 40 mm. The simulation results show that at a permeability of 5.0×10 -9 m 2 When , the wind noise level of Example 3 becomes -15dB relative to that of Comparative Example 3. Fig.31 As shown in the figure, it can be seen that the peak value of the wind noise amount in Example 1 is about -1.5 dB (penetration rate 7.5×10 -9 m 2That is, it can be seen that if the opening area of ​​the communication path is enlarged, the wind noise amount increases, but on the other hand, the wind noise amount reduction effect based on the porous sound absorbing member 22 also increases.

[0242] Explanation of symbols

[0243] 10, 100, 200A, 200B, 200C, 200D, 300a, 300b - ventilated silencers,

[0244] 12, 112, 212, 312-inlet side vent pipe,

[0245] 14, 114, 214, 314- expansion part,

[0246] 16, 116, 216, 316- outlet side vent pipe,

[0247] 18, 118-frame,

[0248] 18a, 18b, 18c, 118a, 118b, 118c-sides,

[0249] 20, 120, 220 - flow path wall,

[0250] 22, 122, 222, 228, 322- porous sound absorbing parts,

[0251] 22a, 122a, 222a-side 1,

[0252] 22b, 122b, 222b-side 2,

[0253] 24, 124, 224, 324-flow space,

[0254] 26, 126, 128, 226, 228a, 326a, 326b - connecting roads,

[0255] 26a, 126a, 128a - corners,

[0256] 30, 130, 230, 330-dorsal space,

[0257] 132-Dust filter,

[0258] 227-Inner wall.

Claims

1. A ventilation type silencer, comprising: an inlet side vent pipe; an expansion portion, which is connected to the inlet side vent pipe and has a cross-sectional area larger than the cross-sectional area of ​​the inlet side vent pipe; and an outlet side vent pipe, which is connected to the expansion portion and has a cross-sectional area smaller than the cross-sectional area of ​​the expansion portion, wherein the ventilation type silencer has: a flow path wall disposed in the expansion portion, communicating the inlet-side vent pipe with the outlet-side vent pipe, and at least a portion of which includes a porous sound absorbing member; and a back space located on the opposite side of the flow path wall from the flow path space in the flow path wall and formed by the flow path wall and the frame of the expansion portion; The porous sound absorbing member has one or more communication paths that connect the flow path space and the back side space.

2. The ventilation type silencer according to claim 1, wherein: The opening diameter of the equivalent circle of the communication path is 1.0 mm to 50.0 mm.

3. The ventilation type silencer according to claim 1, wherein: The permeability of the porous sound absorbing member is 1.0×10 -13 m 2 ~5.0×10 -9 m 2 or 13.0×10 -9 m 2 ~1.0×10 - 5 m 2 .

4. The ventilation type silencer according to claim 1, wherein: If the opening area of ​​the one or more connecting passages is added together, it is 20 mm 2 above.

5. The ventilation type silencer according to claim 1, wherein: The plurality of communication paths are provided at intervals along a flow direction of the gas flowing in the flow path space.

6. The ventilation type silencer according to claim 1, wherein: A dust filter is disposed in the communication passage.

7. The ventilation type silencer according to claim 1, wherein: The frame of the expansion portion is made of resin.

8. The ventilation type silencer according to claim 1, wherein: The temperature of the gas flowing in the flow path space is 20° C. to 80° C. and is higher than the temperature outside the expansion portion.

9. The ventilation type silencer according to claim 1, wherein: The inner surface of the flow path space is constituted by a surface of the porous sound absorbing member and a surface of the frame of the expansion portion, and the communication path is provided so as to be in contact with the surface of the frame of the expansion portion.

10. The ventilation type silencer according to claim 1, wherein: The porous sound absorbing member further includes a first surface in contact with the gas in the flow path space and a second surface in contact with the gas in the back side space. The one or more communication paths penetrate from the first surface to the second surface.

11. The ventilation type silencer according to claim 1, wherein: The cross section of the flow path space perpendicular to the flow direction is rectangular. The inner surface of the flow path space is composed of surfaces of the porous sound absorbing member and the frame body facing each other in a first direction intersecting the flow direction, and surfaces of a pair of porous sound absorbing members facing each other in a second direction intersecting the flow direction and the first direction. The communication paths are formed on three surfaces of the porous sound absorbing member constituting the inner surface of the flow path space.

12. The ventilation type silencer according to claim 1, wherein: The communication path is a through hole.

13. The ventilation type silencer according to claim 1, wherein: The communication path is formed by cutting off one end of the porous sound absorbing member.

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