JP5656284B2 - Silencer and vehicle intake duct - Google Patents

Description

  The present invention relates to a silencer that reduces a noise by generating a cancel wave having a substantially opposite phase to a sound wave of noise, and a vehicle intake duct with a silencer.

  Conventionally, as this type of silencer, a noise is detected by a microphone, and a cancel wave having a substantially opposite phase to the sound wave of the noise is generated by an electric circuit and output from a speaker (for example, Patent Document 1). reference).

Japanese Patent Laid-Open No. 5-46189 (paragraph [0008], FIG. 1)

  However, in the above-described conventional silencer, in order to protect the electric circuit for generating the cancellation wave, it is necessary to perform dustproofing or waterproofing processing, wiring handling processing, etc., and it takes time and effort to install. was there.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silencer and a vehicle intake duct that can reduce the labor and cost of installation as compared with the related art.

The silencer according to the invention of claim 1 made to achieve the above object is a silencer for reducing noise transmitted in the duct, and is arranged side by side through the duct wall of the duct. A pair of circular through-holes, a pair of circular through-holes stretched in a state in which the pair of circular through-holes are closed, and between a pair of transmission / reception films that vibrate by receiving sound waves, and a center portion of the pair of transmission / reception films with contact, is rotatably supported with respect to the duct between the central portion thereof a pair of transmitting and receiving wave film, and a possible transmission seesaw member vibrations between each other a pair of transmitting and receiving wave film, 1 The pair of transmission / reception films and the rotation center of the seesaw member are arranged in substantially the same plane, and the seesaw member is curved in such a way as to communicate between the rotation center and the center of one transmission / reception film. The second bending portion curved so as to communicate between the bending portion and the rotation center and the center portion of the other wave transmitting / receiving film Characterized in place has a substantially E-shaped with.

  The invention according to claim 2 is characterized in that, in the silencer according to claim 1, the pair of transmitting / receiving films are arranged along the sound wave transmission direction in the duct.

According to a third aspect of the present invention, in the silencer according to the first or second aspect , the seesaw member is disposed outside the duct wall, extends toward the duct wall, and has a tip end portion rotatable to the duct wall. The duct wall has a supported center leg, and the duct wall is formed with a recess for avoiding interference with the tip of the center leg. It is characterized in that a foreign substance exclusion hole for discharging into the duct is formed through.

According to a fourth aspect of the present invention, in the silencer according to the third aspect, the rotation center shaft protrudes in opposite directions from both side surfaces of the front end portion of the central leg portion, and the interference avoiding concave portion is formed on the outer surface of the duct wall. It is characterized in that a pair of shaft support grooves are formed on both sides to receive and turnably support the turning center shaft in a state where the distal end portion of the central leg portion is received in the interference avoiding recess.

According to a fifth aspect of the present invention, in the silencer according to the third or fourth aspect , the foreign matter exclusion hole is a circular hole having a diameter larger than a gap between the bottom surface of the interference avoiding concave portion and the front end surface of the central leg portion. It has the characteristics.

According to a sixth aspect of the present invention, in the silencer according to any one of the first to fifth aspects, the rotation range of the seesaw member is restricted to prevent excessive deformation of the wave transmitting / receiving film. It is characterized by the provision of a movement restricting stopper.

According to a seventh aspect of the present invention, in the silencer according to any one of the first to sixth aspects, at least a part of the duct wall is a flat plate-like 1 in which a pair of circular through holes are formed. A pair of base plate members are overlapped, and a pair of wave transmitting / receiving films is formed by a common film member sandwiched between the pair of base plate members.

The invention according to claim 8 is the silencer according to any one of claims 1 to 7 , wherein the seesaw member is disposed outside the duct wall and covers the outer surface of the duct wall together with the seesaw member. It has the feature in having.

Vehicular intake duct according to the invention of claim 9 is disposed in the intake path of the vehicle engine, having characterized in that with a silencer according to any one of claims 1 to 8.

[Invention of Claim 1 ]
According to the silencer of the first aspect, a silencing effect can be obtained as an experimental result described later. The silencing mechanism is assumed to be as follows. That is, the silencer of the present invention includes a pair of wave transmitting / receiving films that receive and vibrate a sound wave. Here, since the sound wave is a wave whose pressure changes at a predetermined cycle, when the wave transmitting / receiving film receives a noise sound wave, the wave transmitting / receiving film bulges inward and bulges outward at the frequency of the noise. It vibrates to repeat the state alternately. In the present invention, when a pair of transmission / reception films are connected by a seesaw member or a vibration transmission member, when one of the transmission / reception films receives a sound wave of noise and vibrates in a predetermined cycle, the other is driven to the other. The transmitting / receiving film vibrates at the same predetermined period, and the bulging direction of one transmitting / receiving film and the bulging direction of the other transmitting / receiving film are always opposite to each other. Accordingly, a cancel wave having a phase opposite to that of the noise sound wave received by one of the transmission / reception films is transmitted from the other transmission / reception film, and noise can be reduced. In addition, since it does not have an electrical circuit for generating a cancel wave, it does not require conventional dustproofing, waterproofing and wiring processing, and can be installed at low cost .
Also, since the pair of transmission / reception films and the center of rotation of the seesaw member are arranged in substantially the same plane, the force acting between the seesaw member and the transmission / reception film in the direction parallel to the transmission / reception film The component is kept small, and the force component in the direction orthogonal to the wave transmitting / receiving film is increased accordingly. That is, when the rotation center of the seesaw member is separated from the surface including the pair of transmission / reception films, the greater the distance is, the more the force acting between the seesaw member and the transmission / reception film is parallel to the transmission / reception film. While the force component in the direction increases, the force component in the direction orthogonal to the transmission / reception film decreases. On the other hand, since the silencer of the present invention has the above-described configuration, the force component in the direction parallel to the transmission / reception film is the smallest, and the force component in the direction orthogonal to the transmission / reception film is the largest. Thereby, the vibration of the wave transmission / reception film is stabilized and the vibration received on one side of the wave transmission / reception film can be efficiently transmitted to the other side.

[Invention of claim 2]
According to the silencer of the second aspect, since the pair of transmission / reception films are arranged along the sound wave transmission direction, a differential pressure is generated between the pair of transmission / reception films due to reception of sound waves when the noise is low frequency. It is easy to vibrate the wave transmitting / receiving film and the silencing effect is improved. According to the experiment described later, although a silencing effect was obtained even when a pair of transmission / reception films were arranged in a direction perpendicular to the sound wave transmission direction, a pair of transmission / reception films was obtained when the noise was low frequency. It was confirmed that a higher silencing effect was obtained when the sound waves were arranged in the sound wave transmission direction.

[Inventions of Claims 3 and 4 ]
According to the configuration of the third aspect , even if foreign matter such as dust enters the interference avoiding recess recessed in the duct wall in order to avoid interference with the center leg of the seesaw member, Since it is discharged into the inside, it is possible to prevent foreign matter from accumulating in the interference avoiding recess. Thereby, the state in which the seesaw member can be smoothly rotated is maintained.
According to the structure of Claim 4 , a rotation center shaft can be assembled | attached to a shaft support groove from the direction orthogonal to the axial direction, and an assembly | attachment operation | work becomes easy.

[Invention of claim 5 ]
In the silencer according to the fifth aspect , since the foreign substance exclusion hole is a circular hole having a diameter larger than the gap between the bottom surface of the interference avoiding recess and the front end surface of the central leg, the inside of the duct is in a negative pressure state. In this case, the foreign matter can be discharged into the duct through the foreign matter exclusion hole.

[Invention of claim 6 ]
According to the silencer of the sixth aspect , the rotation range of the seesaw member can be regulated by the rotation regulating stopper, and excessive deformation of the wave transmitting / receiving film can be prevented.

[Invention of Claim 7 ]
According to the silencer of the seventh aspect, since a pair of wave transmitting and receiving films are formed by sandwiching a common film member between a pair of base plate members each having a pair of circular through-holes, The number of parts can be reduced as compared with the case where the film is formed of separate film members.

[Invention of Claim 8 ]
According to the silencer of the eighth aspect , since the seesaw member is disposed on the outer surface side of the duct, it is not affected by the fluid resistance of the air passing through the duct. Further, since the seesaw member is covered with the outer surface cover, contact between the seesaw member and other parts is prevented, and the silencer and the duct including the silencer are easily handled.

[Invention of claim 9 ]
The vehicle intake duct according to claim 9 is equipped with the silencer according to any one of claims 1 to 8 , and therefore, when installed in a vehicle, conventional dustproof, waterproof and wiring processing are required. It can be installed at low cost.

The perspective view of the air intake duct with a silencer concerning a 1st embodiment of the present invention. Disassembled perspective view of intake duct with silencer Side cross-sectional view of air intake duct with silencer Schematic diagram showing the operation of the silencer Side sectional view showing a part of a modification of the silencer The perspective view of the air intake duct with a silencer concerning a 2nd embodiment Perspective view of air intake duct with silencer with outer cover removed Disassembled perspective view of intake duct with silencer A perspective view of the lower surface side of the second base plate member Perspective view of interference avoidance recess and shaft support groove Partial sectional view of the first base plate member and the second base plate member Perspective view of seesaw member Perspective view of the underside of the silencer Perspective view of the bottom side of the outer cover A perspective view of an air intake duct with a silencer according to Reference Example 1 . The perspective view of the implementation goods of this invention Graph of frequency and reduced volume showing results of comparative experiment Graph of frequency and reduced volume showing results of comparative experiment Graph of frequency and reduced volume showing results of comparative experiment

[First Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a part of a vehicle intake duct 10 (hereinafter simply referred to as “duct 10”) provided with a silencer 20 according to the present invention. One end of the duct 10 is connected to the engine 90 side of the vehicle, and guides the air taken in from the other end to the engine 90. Here, since the duct 10 also serves as a transmission conduit for transmitting noise from the engine 90, a silencer 20 for reducing the noise is provided.

  Specifically, the duct 10 is, for example, divided into two upper and lower duct structures 10A and 10B by a horizontal dividing surface 10C including a central axis that has a cylindrical shape extending in the horizontal direction. The duct structural bodies 10A and 10B are formed by injection molding of resin, and are fixed to each other by, for example, vibration welding.

  A part of the duct wall 10 </ b> W that partitions the inside and the outside of the duct 10 bulges upward to form a box-shaped bulging portion 11. The box-shaped bulging portion 11 has a rectangular parallelepiped shape extending in the axial direction of the duct 10, and the rectangular flat base wall 12 provided at the tip of the box-shaped bulging portion 11 has a pair of circular through holes 13, 13 are arranged in the axial direction of the duct 10. The membrane member 15 is stretched so as to close the pair of circular through holes 13 and 13 to form a pair of transmission / reception films 21A and 21B, and the center portions of the pair of transmission / reception films 21A and 21B The silencer 20 is configured by communicating with the seesaw member 22.

  Specifically, as shown in FIG. 2, the base wall 12 includes, for example, a rectangular flat plate-like first base plate member 31 formed integrally with the upper end of the side wall of the box-shaped bulging portion 11, and the first base plate. The second base plate member 32 is stacked on the outer surface of the member 31. The pair of circular through holes 13 and 13 have the same diameter, and the pair of circular through holes 13 and 13 penetrates the first and second base plate members 31 and 32 at the same pitch. Is formed. Further, an adhesive is applied to the opposing surfaces of the first and second base plate members 31, 32, and the film member 15 is disposed between them, and the first and second base plate members are provided by a plurality of screws. 31 and 32 and the membrane member 15 are fastened together. And the part exposed from one pair of circular through-holes 13 and 13 among the film | membrane members 15 becomes one pair of transmission / reception films | membranes 21A and 21B (refer FIG. 1).

  The film member 15 is a rubber or resin sheet, and specific examples of the material thereof include EPDM, TPU, TPO, PVC, and PET. Moreover, the thickness of the membrane member 15 is, for example, about 0.1 to 1.0 [mm].

  Between the pair of circular through holes 13 and 13 in the second base plate member 32, a slit 16 extending along a line connecting the center points of the circular through holes 13 and 13 is formed. A pair of shaft support protrusions 17S, 17S are formed on both sides of the slit 16 in the width direction on the side of the second base plate member 32 facing the first base plate member 31, and these shaft support members are supported. A rotation center shaft 18S is provided between the protrusions 17S and 17S.

  The rotation center shaft 18S is located at the center between the center points of the pair of circular through holes 13 and 13 and is disposed in substantially the same plane as the membrane member 15 (see FIG. 3). Then, the center leg portion 23 described below of the seesaw member 22 is passed through the slit 16 from the outer surface side of the second base plate member 32, and the center of rotation is inserted into the shaft insertion hole 23 </ b> S provided at the end of the center leg portion 23. The shaft 18S is inserted, whereby the seesaw member 22 is rotatably supported on the base wall 12 via the rotation center shaft 18S. In order to avoid interference between the lower end portion of the central leg 23 and the membrane member 15 and the first base plate member 31, an interference avoidance hole 15 </ b> A is formed in the membrane member 15, and the outer surface of the first base plate member 31 is formed. The interference avoiding recess 31A is recessed.

  As shown in FIG. 1, the seesaw member 22 is, for example, a substantially E-shaped resin plate, and extends along a line connecting the center points of the circular through holes 13, 13. A central leg 23 extending from the longitudinal center of the connecting portion 24 in a direction orthogonal to the connecting portion 24, and a pair of end portions extending from both ends of the connecting portion 24 parallel to the central leg 23 Legs 25 and 25 are provided. As shown in FIG. 3, the end surfaces of the end leg portions 25, 25 and the shaft insertion hole 23 </ b> S of the central leg portion 23 are arranged in substantially the same plane. Furthermore, the distance between the centroids of the end faces of the end leg portions 25, 25 is the same as the distance between the center points of the wave transmitting / receiving films 21A, 21B. As described above, the distal end portion of the central leg portion 23 is rotatably supported by the base wall 12 via the rotation center shaft 18S, and the centroids on the distal end surfaces of the end leg portions 25 and 25 are transmitted and received. The tip surfaces of the end leg portions 25, 25 are fixed to the outer surfaces of the wave transmitting / receiving films 21A, 21B with an adhesive in a state where they coincide with the center points of the films 21A, 21B. In the present embodiment, the curved portion formed of one end leg portion 25, the central leg portion 23, and the connecting portion 24 between them is the “first curved portion” according to the present invention. The curved portion including the other end leg portion 25, the central leg portion 23, and the connecting portion 24 connecting them corresponds to the “second curved portion” according to the present invention.

  The outer surface of the silencer 20 is covered with an outer surface cover 27. The outer surface cover 27 has a trapezoidal box structure with the entire bottom surface opened, and the opening edge of the rectangular opening 27A on the bottom surface is directed to the base wall 12 with screws in a state where the opening edge is directed to the outer edge portion of the second base plate member 32. It is fixed.

  As shown in FIG. 3, rotation restriction stoppers 51 and 51 are provided at positions facing the both end portions of the seesaw member 22 on the inner surface of the outer cover 27 from the side opposite to the wave transmitting / receiving films 21 </ b> A and 21 </ b> B. . The rotation restricting stoppers 51 and 51 maintain a separated state with respect to the seesaw member 22 in a normal use method of the silencer 20, for example, the wave transmitting / receiving film 21A is pushed by a tool or the like and the seesaw member 22 is rotated. At the time of an abnormal movement, the contact with the seesaw member 22 prevents excessive deformation of the wave transmitting / receiving film 21A.

  The description regarding the structure of the silencer 20 of this embodiment is above. Next, the function and effect of the silencer 20 will be described. The engine 90 operates by taking in air through the duct 10. Then, the intake sound generated by the engine 90 becomes noise and travels through the duct 10 in the direction opposite to the intake direction as shown in FIG. 21A passes through the other transmission / reception film 21B and is discharged out of the duct 10. However, since the silencer 20 according to the present invention is provided in the duct 10, noise can be reduced as confirmed in the experiment described later. The silencing mechanism is assumed to be as follows.

  That is, since the sound wave is a wave whose pressure changes in a predetermined cycle, when one of the transmission / reception films 21A receives the sound wave of the noise, it is in a state of bulging inward and bulging outward at the noise frequency. And vibrate to repeat alternately. Here, since the transmission / reception films 21A and 21B are connected to each other by the seesaw member 22, when one of the transmission / reception films 21A receives a sound wave of noise and vibrates in a predetermined cycle, the other transmission / reception wave follows. The film 21B also vibrates at the same predetermined period, and as shown in FIGS. 4B and 4C, the bulging direction of one transmitting / receiving film 21A and the bulging direction of the other transmitting / receiving film 21B are always set. They are opposite to each other. Accordingly, a cancel wave having a phase opposite to that of the sound wave of noise received by one of the transmission / reception films 21A is transmitted from the other transmission / reception film 21B, and noise can be reduced. Moreover, since the silencer 20 of this embodiment does not have an electrical circuit for generating a cancel wave, it does not require conventional dustproofing, waterproofing and wiring processing, and can be installed in a vehicle at a low cost.

  Further, in the silencer 20 of the present embodiment, as shown in FIG. 3, the pair of wave transmitting / receiving films 21 </ b> A and 21 </ b> B and the rotation center P <b> 1 of the seesaw member 22 are arranged in substantially the same plane. The force component in the direction parallel to the transmission / reception films 21A and 21B is suppressed to be small among the forces acting between the transmission / reception films 21A and 21B, and the force component in the direction orthogonal to the transmission / reception films 21A and 21B is reduced accordingly. Becomes larger. Specifically, for example, as shown in comparison with FIGS. 5A and 5B, the rotation center P1 of the seesaw member 22 is separated from the surface including the pair of transmission / reception films 21A and 21B. As the distance increases, the force component Fx in the direction parallel to the transmission / reception film 21B increases from the force F applied from the seesaw member 22 to the transmission / reception film 21B (from Fx in FIG. 5A). The force component Fy in the direction orthogonal to the transmission / reception film 21B decreases (see that Fx in FIG. 5B is large). On the other hand, in the silencer 20 of the present embodiment, the pair of transmission / reception films 21A and 21B and the rotation center P1 of the seesaw member 22 are arranged in substantially the same plane, so the transmission / reception film 21B from the seesaw member 22 is provided. While the component Fx in the direction parallel to the transmission / reception film 21B is the smallest (ie, suppressed to “0”), the force component Fy in the direction orthogonal to the transmission / reception film 21B is the largest. . Although not shown, the same applies to the force that the seesaw member 22 receives from the wave transmitting / receiving film 21A. Thereby, in this embodiment, the vibration of the transmission / reception films 21A and 21B is stabilized, and the vibration received by one of the transmission / reception films 21A and 21B can be efficiently transmitted to the other.

  Furthermore, a pair of transmission / reception films 21A, with a common film member 15 sandwiched between a pair of first and second base plate members 31, 32 each having a pair of circular through holes 13, 13. Since 21B is configured, the number of parts can be reduced as compared with the case where each of the transmission / reception films 21A and 21B is configured by separate film members. In this embodiment, since the seesaw member 22 is covered with the outer surface cover 27, the seesaw member 22 is prevented from coming into contact with other parts, and the duct 10 can be handled easily.

[Second Embodiment]
Hereinafter, the structure different from the silencer 20 of 1st Embodiment among the silencers 20V which concern on 2nd Embodiment of this invention is demonstrated, referring FIGS. 6-14.

  As shown in FIG. 7, the second base plate member 32V of the silencer 20V of the present embodiment has a rectangular shape that is slightly smaller than the first base plate member 31V. As shown in FIG. 9, a pair of rectangular membrane members 15, 15 are laid on the lower surface of the second base plate member 32 </ b> V so as to close the pair of circular through holes 13, 13. Further, a plurality of film fixing protrusions 32T protruding from the lower surface of the second base plate member 32V pass through the four corners of each film member 15, and the space between each film member 15 and the lower surface of the second base plate member 32V is between. For example, it is fixed by an adhesive. And the part exposed from a pair of circular through-holes 13 and 13 among the film | membrane members 15 becomes one pair of transmission / reception films | membranes 21A and 21B.

  As shown in FIG. 8, the interference avoiding recess 19 is recessed and formed between the pair of circular through holes 13 on the upper surface of the second base plate member 32V. Here, a center connecting line L10 (see FIG. 10) connecting the center points of the pair of circular through holes 13, 13, and a membrane member 15 (specifically, a membrane member) perpendicular to the center of the center connecting line L10. 15 and the rotation center line L11 (see FIGS. 10 and 11) included in substantially the same plane, the interference avoidance recess 19 has the rotation center line L11 as the center axis as shown in FIG. The arc groove has a semicircular bottom surface 19A. In addition, the groove inner side surfaces 19B and 19B facing each other in the direction of the center connecting line L10 (see FIG. 10) in the interference avoiding recess 19 are inclined so that the distance between them increases as the distance from the semicircular bottom surface 19A increases. Further, as shown in FIG. 10, a circular foreign material exclusion hole 19 </ b> C is formed through the center of the lowermost part of the semicircular bottom surface 19 </ b> A in the interference avoiding recess 19.

  Shaft support grooves 18 and 18 are recessed and formed on both sides of the interference avoiding recess 19 in the upper surface of the second base plate member 32V. The shaft support grooves 18 and 18 are circular grooves whose width and depth are smaller than those of the interference avoidance recess 19, and have semicircular bottom surfaces 18 A centering on the rotation center line L 11. It communicates with the surface. Moreover, the groove inner side surfaces 18B and 18B which face each other in the direction of the center connecting line L10 in the shaft support groove 18 are parallel to each other as shown in FIG.

  As shown in FIG. 12, each end leg 25 of the seesaw member 22 </ b> V of the present embodiment is provided with a circular flange 25 </ b> F in the middle in the vertical direction, and from the center of the lower end surface of the end leg 25. A round bar-shaped through shaft 25T protrudes. Further, as shown in FIG. 11, the lower end surface of the circular flange 25F is arranged to be included in the same plane as the above-described rotation center line L11. The through shafts 25T and 25T are inserted through center holes 21C and 21C (only one center hole 21C is shown in FIG. 11) formed in the center of the wave transmitting / receiving films 21A and 21B. Further, a membrane fixing washer 25W is inserted into the through shaft 25T from below the transmission / reception films 21A and 21B and fixed with an adhesive, and the transmission / reception film 21A is interposed between the film fixing washer 25W and the circular flange 25F. , 21B is sandwiched.

  As shown in FIG. 12, the center leg portion 23 of the seesaw member 22V projects a pair of large-diameter shafts 23B and 23B on both side surfaces of the tip end of the projecting piece portion 23A suspended from the center in the width direction of the connecting portion 24. The rotation center shafts 23C and 23C are projected from the front end surfaces of the large diameter shafts 23B and 23B. The large-diameter shaft 23B and the rotation center shaft 23C are concentric round bars with the rotation center line L11 as a central axis, and the rotation center shaft 23C is thinner than the large-diameter shaft 23B. The distal end portion of the leg main body 23H composed of the projecting piece portion 23A and the large diameter shafts 23B and 23B is received in the interference avoiding recess portion 19, while the pair of rotation center shafts 23C and 23C are the shaft support grooves 18, 18 is accepted. Further, as shown in FIG. 11, the rotation center shafts 23C and 23C are supported so as to be slidably contacted with the circular bottom surfaces 18A and 18A of the shaft support grooves 18 and 18, and the leg main body 23H includes an interference avoiding recess. It is in a state of floating from the inner surface of 19. As a result, the seesaw member 22V rotates about the rotation center line L11.

  The diameter of the foreign matter exclusion hole 19 </ b> C is larger than the gap between the leg main body 23 </ b> H and the inner surface of the interference avoiding recess 19.

  As shown in FIG. 8, a plurality of locking pieces 17 hang from the outer edge portions of the four sides of the second base plate member 32V. In addition, a triangular locking projection 17A is provided on the outer surface side of the tip of each locking piece 17. Then, a group of locking pieces 17 is inserted into a plurality of first locking slits 35A formed through the first base plate member 31V, and as shown in FIG. 13, each locking projection 17A has a first base plate member 31V. The second base plate member 32V is integrally fixed to the first base plate member 31V by being locked to the inner surface of the first base plate member 31V.

  As shown in FIG. 8, annular projections 33, 33 project from the upper surface of the first base plate member 31V toward the opening edges of the circular through holes 13, 13 of the second base plate member 32V. The inner sides of the annular projections 33 and 33 are circular through holes 13 and 13 of the first base plate member 31V. In addition, as shown in FIG. 11, in the state where the second base plate member 32V is fixed to the first base plate member 31V, the tip surfaces of the annular projections 33, 33 are circular through holes in the second base plate member 32V. Membrane members 15 and 15 are sandwiched between the opening edges of 13 and 13. Further, a central rectangular window 36 is formed between the annular protrusions 33, 33 of the first base plate member 31V, and a bulge protrusion on the back side of the interference avoiding recess 19 of the second base plate member 32V. The portion 19E enters the central rectangular window 36.

  As shown in FIG. 6, the outer surface of the silencer 20V is covered with an outer surface cover 27V. As shown in FIG. 14, the outer surface cover 27V has a rectangular parallelepiped structure with the entire bottom surface open and flat in the vertical direction, and its planar shape is slightly larger than the second base plate member 32V, and the first base plate member 31V. It is a slightly smaller rectangle. A plurality of locking pieces 28A are suspended from the opening edge on the short side of the rectangular opening 27A on the bottom surface of the outer cover 27V, while a plurality of abutting pieces 28B are suspended from the opening edge on the long side. Yes. The abutting piece 28B has a projecting piece shape with a flat bottom surface, and the locking piece 28A extends downward from the abutting piece 28B and is latched in the same manner as the locking projection 17A of the locking piece 17. A protrusion 28T is provided on the outer surface. Then, as shown in FIG. 13, the second locking portion in which the front end surface of the abutting piece 28B is abutted against the upper surface of the first base plate member 31V and the locking piece 28A is formed to penetrate the first base plate member 31V. The locking projection 28T is inserted into the slit 35B and locked to the inner surface of the first base plate member 31V, whereby the outer surface cover 27V is fixed to the first base plate member 31V.

  Further, as shown in FIG. 14, a pair of ceiling ribs 29L, 29L extending in the same direction as the seesaw member 22V are provided on the inner upper surface of the outer cover 27V, and one pair from the center of the ceiling ribs 29L, 29L. The non-sticking protruding pieces 29 and 29 are suspended. The retaining protrusions 29 and 29 are abutted against the upper surface of the second base plate member 32V (not shown) in a state of crossing the upper surface openings of the shaft support grooves 18 and 18 in the second base plate member 32V. Thus, the rotation center shafts 23C, 23C are prevented from coming off in the shaft support grooves 18, 18.

  This completes the description of the configuration of the silencer 20V of the present embodiment. In the silencer 20V of the present embodiment, as shown in FIG. 11, the foreign substance exclusion hole 19C is provided at the bottom of the interference avoiding recess 19 that receives the center leg 23 of the seesaw member 22V. Even if dust or the like enters the gap between the recesses 19, the negative pressure in the duct 10 is received and the dust and the like are removed from the foreign matter exclusion hole 19 </ b> C into the duct 10, thereby preventing dust from accumulating. . Thereby, the seesaw member 22V is maintained in a state in which the seesaw member 22V can be smoothly rotated, and also in this respect, a reduction in the silencing performance is prevented and durability is improved.

[ Reference Example 1 ]
The duct 10Z provided with the silencer 20Z according to Reference Example 1 of the present invention is shown in FIG. In this duct 10Z, a pair of square tubular bulging portions 40, 40 are provided side by side in the axial direction of the duct 10Z, and a pair of circular bulges are formed on the opposing surfaces of the pair of square tubular bulging portions 40, 40. The through holes 41 are formed so as to be aligned on the same axis. Then, a membrane member is stretched so as to close the pair of circular through holes 41, 41 to form a pair of transmission / reception films 42A, 42B, and between the center portions of the pair of transmission / reception films 42A, 42B. Is communicated by a vibration transmission member 49 to constitute a silencer 20Z. The silencer 20Z of the present reference example can reduce the noise by transmitting a cancel wave to the sound wave of the noise transmitted through the duct 10Z, similarly to the silencer 20 of the first embodiment.

[Example 1]
Hereinafter, comparative experimental results of the silencing effect performed by manufacturing the products 1 and 2 of the present invention , the reference product 1 and the comparative products 1 and 2 lacking a part of the invention specific matters of the present invention will be described. As shown in FIG. 16, the implementation product 1 has a silencer 20 similar to that of the first embodiment at a position close to the end in the longitudinal direction in the duct 10 having an overall length L1 of 400 [mm] and an inner diameter D3 of φ56 [mm]. It has a structure with. The diameters (that is, the diameters of the circular through holes 13 and 13) D1 and D2 of the wave transmitting / receiving films 21A and 21B in the silencer 20 are both φ50 [mm], and the distance L3 between the center points of the wave transmitting / receiving films 21A and 21B. Is 60 [mm], and the distance L2 from the end of the duct 10 to the center position between the center points of the transmission / reception films 21A and 21B is 100 [mm]. The wave transmitting / receiving films 21A and 21B are both made of EPDM (ethylene propylene rubber) having a film thickness of 0.3 [mm].

In the implementation product 2, the diameter of the transmission / reception films 21A and 21B in the silencer 20 is D1 = D2 = φ35 [mm], and the distance between the center points of the transmission / reception films 21A and 21B is L3 = 50 [mm]. Except for this point, the configuration is the same as that of the working product 1. The reference product 1 has the same configuration as that of the implementation product 1 except that the transmission / reception films 21A and 21B are arranged in a direction orthogonal to the axial direction of the duct 10.

  The comparative product 1 has a simple cylindrical structure in which the silencer 20 is excluded from the product 1. That is, the comparative product 1 is a simple cylindrical duct having an inner diameter of 56 [mm] and a total length of 400 [mm]. The comparison product 2 has a structure in which the seesaw member 22 is excluded from the implementation product 1, and the other configuration is the same as that of the implementation product 1.

(experimental method)
(1) The experimental method is as follows. That is, as shown in FIG. 16, the speaker 92 is disposed opposite to the opening of the start end of the duct 10 in the embodiment product 1, and the start end microphone 91 </ b> A and the end microphone 91 </ b> B are disposed at the start end and the end end of the duct 10. If the frequency of the sound output from the speaker 92 is changed in the range of 50 to 800 [Hz], the sound is picked up by the start microphone 91A and the end microphone 91B. Then, for each frequency, a differential volume obtained by subtracting the volume picked up by the start microphone 91A from the volume picked up by the terminal microphone 91B is obtained, and the graph g1 shown in FIGS. 17 and 19 is created. Further, in the same procedure, a graph g2 of FIG. 18 is created using the implementation product 2 instead of the implementation product 1 , a graph g3 of FIG. 19 is created using the reference product 1, and a graph is created using the comparison product 1. The graph h1 of FIGS. 17-19 is created, and also the graph h2 of FIG.

(Experimental result)
As shown in FIG. 17, the duct 10 provided with the silencer 20 (implemented product 1: graph g1) and 130 (comparative product 1: graph h1) not provided with the silencer 20 are 130. It was confirmed that a silencing effect could be obtained in a frequency band of ˜400 [Hz]. Thus, since the silencing effect could be confirmed in a wide frequency band of 130 to 400 [Hz], a wider frequency band than a silencer having a Helmholtz resonance chamber generally used in an intake duct. The present invention is effective when noise reduction is required. Further, in the Helmholtz resonance chamber, a capacity of about 2000 to 3000 [cc] is necessary to obtain a noise reduction effect by resonating with a noise of about 130 [Hz], but the silencer 20 according to the present invention is provided. In the case of the embodiment product 1, the size is such that the seesaw member 22 is provided by arranging the transmission / reception films 21 </ b> A and 21 </ b> B of φ50 [mm], and therefore 200 [mm] × 100 [mm] × 30 [mm] It can be accommodated in a volume of about 600 [cc], thus saving space.

  In addition, as shown in FIG. 17, even if the transmission / reception films 21A and 21B are not connected by the seesaw member 22 (comparative product 2: graph h2), a certain silencing effect can be obtained. It was also confirmed that 21A and 21B communicated with the seesaw member 22 (implemented product 1: graph g1) can obtain a greater silencing effect.

  In addition, when the natural frequency of the transmission / reception films 21A and 21B and the seesaw member 22 of the product 1 having the silencer 20 in the duct 10 is calculated, it is about 120 [Hz], and the natural vibration that can appear even in a normal silencer. A sudden change (under fluctuation) of the silencing effect before and after the number was confirmed on the graph g1 (see FIG. 17). However, in the graph g2 (see FIG. 18) of the implementation product 2 in which the diameters of the transmission / reception films 21A and 21B are different from those of the implementation product 1, the frequency of the sudden change (under fluctuation) of the silencing effect changes to around 300 [Hz] and the sound can be silenced. The frequency band and the silencing effect have also changed. Therefore, according to the present invention, it is considered that the targeted noise can be efficiently silenced by changing the diameters of the transmission / reception films 21A and 21B according to the frequency of the noise.

  Furthermore, as shown in FIG. 19, the silencing effect when the transmission / reception films 21 </ b> A and 21 </ b> B are arranged in the traveling direction of sound and the silencing effect when arranged in the direction orthogonal to the traveling direction are 110 to 110. In the low frequency region of about 140 [Hz] (“R” in FIG. 19), it was confirmed that the sound deadening effect is higher when the wave transmitting / receiving films 21A and 21B are arranged in the sound traveling direction.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

  (1) In the first and second embodiments, the seesaw member 22 that communicates between the transmission / reception films 21A and 21B is disposed outside the duct 10, but may be disposed in the duct. However, since the seesaw member can be rotated by the wind pressure in the duct, it is preferable to dispose the seesaw member outside the duct.

(2) In the first and second embodiments, the duct 10 is provided with only the silencer 20, 20V, 20Z according to the present invention. However, a conventionally known silencer and a silencer according to the present invention are provided. May be provided in the duct in combination.

(3) In the first and second embodiments, the silencer 20 and the like are provided in the vehicle intake ducts 10 and 10Z. However, the silencer according to the present invention is applied to other ducts and portions other than the ducts. May be provided. For example, a muffler according to the present invention may be provided by forming a pair of circular through holes in the inner wall of an engine room of a vehicle and attaching a transmission / reception film there.

  (4) In the first and second embodiments, the seesaw member 22 is attached to the duct wall 10W. However, the seesaw member may be attached to a portion other than the duct as long as it can be rotated with respect to the duct.

  (5) Although the outer surface covers 27 and 27V of the silencers 20 and 20V of the first and second embodiments are attached to the base wall 12 with screws or locking pieces, the outer surface covers are attached by adhesive or welding. You may attach to a base wall.

  (6) In the second embodiment, the foreign matter exclusion hole 19C is provided on the bottom surface of the interference avoiding recess 31A, but may be provided on the inner surface of the interference avoiding recess 31A.

  (7) The silencer 20 of the first embodiment may also be provided with a foreign substance exclusion hole 19C in the interference avoidance recess 31A, similar to the silencer 20V of the second embodiment.

10, 10Z Duct 10W Duct Wall 13, 41 Circular Through Hole 15 Membrane Member 17 Locking Piece 17S Shaft Support Projection 18 Shaft Support Groove 18S, 23C Turning Center Shaft 19, 31A Interference Avoiding Recess 19C Foreign Object Exclusion Hole 20, 20V, 20Z silencer 21A, 21B, 42A, 42B Transmitting / receiving film 22, 22V Seesaw member 23 Central leg 23B Large diameter shaft 23H Leg main body 27, 27V Outer cover 29 Vibration transmission member 31, 31V First base plate member 32, 32V Second base plate member 51 Rotation restriction stopper

Claims (9)

A silencer for reducing noise transmitted in the duct,
A pair of circular through holes arranged side by side through the duct wall of the duct;
A pair of wave transmitting and receiving films that are stretched in a state in which the pair of circular through holes are closed, and receive and oscillate sound waves;
The center of the pair of transmission / reception membranes communicates with each other, and is supported rotatably with respect to the duct between the center of the pair of transmission / reception membranes. With a seesaw member capable of transmitting vibration between each other ,
The pair of wave transmitting / receiving films and the rotation center of the seesaw member are arranged in substantially the same plane, and the seesaw member communicates between the rotation center and the central part of one of the wave transmitting / receiving films. The first curved portion curved in this manner and the second curved portion curved so as to communicate between the rotation center and the central portion of the other wave transmitting / receiving film. A silencer characterized by.   The silencer according to claim 1, wherein the pair of wave transmitting / receiving films are arranged along a sound wave transmission direction in the duct. The seesaw member is disposed outside the duct wall, and has a center leg portion that extends toward the duct wall and has a distal end portion rotatably supported by the duct wall.
An interference avoidance recess for avoiding interference with the front end of the central leg is formed in the duct wall, and an inner surface of the interference avoidance recess for discharging foreign matter into the duct. The silencer according to claim 1 or 2, wherein the foreign matter exclusion hole is formed to penetrate therethrough. The pivot center shafts project in opposite directions from both side surfaces of the front end of the central leg,
On the both sides of the interference avoiding recess on the outer surface of the duct wall, the tip of the central leg is received in the interference avoiding recess so as to receive and support the rotating center shaft 1. The silencer according to claim 3, wherein a pair of shaft support grooves are formed. 5. The silencer according to claim 3, wherein the foreign matter exclusion hole is a circular hole having a diameter larger than a gap between a bottom surface of the interference avoiding recess and a front end surface of the central leg portion. The rotation control stopper for restricting the rotation range of the said seesaw member and preventing the excessive deformation | transformation of the said transmission / reception film | membrane is provided in any one of Claims 1 thru | or 5 characterized by the above-mentioned. The listed silencer. At least a part of the duct wall is formed by stacking a pair of flat base plate members each formed with a pair of circular through holes, and sandwiched between the pair of base plate members. The silencer according to any one of claims 1 to 6, wherein the pair of wave transmitting / receiving films are configured by a common film member. The said seesaw member is arrange | positioned on the outer side of the said duct wall, The outer surface cover which covers the outer surface of the duct wall with the said seesaw member is provided, The claim of any one of Claim 1 thru | or 7 characterized by the above-mentioned. Silencer. An air intake duct for a vehicle, comprising the silencer according to any one of claims 1 to 8, which is disposed in an air intake path of an engine of the vehicle.