TWI659148B - Silencer - Google Patents

Abstract

The muffler (1) is provided with an expansion part (20) having a discharge port (22) and defining an expansion chamber (21) inside, and an induction tube (10) having a limited length defining an induction chamber (11) inside An acoustic component, a connection portion (30) provided with a communication hole (32) for communicating the expansion chamber (21) and the induction chamber (11), and preventing expansion from the induction chamber (11) through the communication hole (32) Backflow check valve (5) for compressed air flowing in the chamber (21). The check valve (5) includes a valve seat (33) provided at the connection portion (30), a valve body (25) that abuts the valve seat (33) and plugs the communication hole (32), and a valve The body (25) springs against the valve seat (33). The valve body (25) is provided with a tapered portion (25a), a flat plate portion (25b), and a recessed portion (25c). The tapered portion (25a) is a portion provided at the peripheral portion and abutting against the valve seat (33), and has The shape is tapered toward the valve seat (33). The flat plate portion (25b) is provided inside the tapered portion (25a), and the recessed portion (25c) is provided on the opposite side of the surface facing the valve seat (33).

Description

silencer

[0001] The present invention relates to a muffler.

[0002] It is known that a device with fluid movement, such as a pump or a compressor, generates a large sound wave at the outlet of the fluid, which causes noise. From the viewpoint of preventing noise, it is useful to attenuate the sound wave. [0003] A muffler having such a sound wave attenuation function is disclosed in, for example, Patent Document 1. The muffler of Patent Document 1 has a muffler function for reducing noise included in a gas discharged from an exhaust port of a vacuum pump. Furthermore, the muffler is provided with a check valve, and in addition to the above-mentioned muffler function, it also has a backflow suppression function that suppresses the backflow of gas. [0004] [Patent Document 1] JP 2001-289167

[Problems to be Solved by the Invention] [0005] The check valve provided in the muffler of Patent Document 1 is provided for realizing a backflow suppression function, and does not have a function as a muffler element. Therefore, the silencer has room for improvement in the structure of the check valve. [0006] An embodiment of the present invention has been developed in view of this situation, and an object thereof is to provide a muffler having a check valve structure having both a backflow suppression function and a muffler function. [Technical means to solve the problem] [0007] A muffler according to an embodiment of the present invention includes: an expansion part having a discharge port and an expansion chamber defined therein; and an induction tube of a limited length that defines an induction chamber therein. An acoustic element, a connection portion provided with a communication hole for communicating the expansion chamber and the induction chamber, and a check valve for preventing a fluid from flowing from the induction chamber through the communication hole to the expansion chamber to flow back, The return valve system includes a valve seat provided at the connection portion, a valve body contacting the valve seat and plugging the communication hole, and an elastic member that urges the valve body toward the valve seat. The constricted portion, the flat plate portion, and the recessed portion. The tapered portion is a portion provided on the peripheral edge portion and abuts the valve seat. The tapered portion has a shape that is tapered toward the valve seat. The recessed portion is provided on a surface opposite to a surface facing the valve seat. [0008] According to this structure, a muffler having a check valve structure having both a backflow suppression function and a muffler function can be provided, which can save space and obtain a higher muffler effect than in the past. Specifically, when the valve body is in contact with the valve seat, the communication hole is closed by the tapered portion, so that the communication hole can be reliably closed. If the valve body does not have a tapered portion and the communication hole is plugged by the flat plate portion, the assembly tolerance or manufacturing tolerance of the flat plate portion may not reliably abut the valve seat, that is, the communication hole cannot be reliably plugged. And cannot function as a check valve. According to the above structure, this problem can be suppressed by the tapered portion, and the backflow of the fluid can be stably suppressed. Moreover, by making a part of the valve body tapered, the rigidity of the valve body can be improved, and the thickness of the plate for obtaining the necessary flexural rigidity can be reduced. As a result, the valve body can be made lighter than when it is simply flat, which contributes to cost reduction. In addition, the valve body is in contact with the valve seat at the tapered portion, and the flow path of the fluid is gradually widened compared to the case where the contact is made at the flat portion, so that an increase in pressure loss can be suppressed. In addition, the check valve is provided with an elastic member, and the check valve is opened only when the pressure on the upstream side (the induction chamber side) of the elastic member is higher than the downstream side (the expansion chamber side) by a certain degree or more. That is, the backflow suppression function can be easily realized by using the elastic member. In addition, the valve body has a recessed portion on the opposite side of the surface facing the valve seat, and a sound wave overlapping with the fluid passing through the communication hole will entangle the recessed portion and cause a diffraction phenomenon. Therefore, the sound reduction effect caused by the diffraction attenuation of the sound wave can be obtained. In addition, since the surface holding the valve body is different from the surface having the discharge port, the valve body can be accessed from outside the discharge port. Therefore, even when piping is provided below the discharge port, maintenance of the check valve can be performed without removing the piping. In order to efficiently maintain the check valve, it is preferable to provide an opening other than the discharge port in the expansion portion, and the check valve can be accessed from outside the discharge port. [0009] The muffler may further include a restriction member for restricting a maximum opening degree of the check valve. [0010] According to this structure, the maximum opening of the check valve can be restricted by the restricting member, and the noise reduction effect can be prevented from being significantly weakened. Specifically, when the opening degree of the check valve is increased, the sound waves that pass through the discharge port without drying up with the valve body increase, so the amount of sound wave attenuation caused by the valve body becomes small. That is, the closer the valve body is located to the valve seat, the greater the noise reduction effect can be expected. According to the above structure, the maximum opening degree of the check valve is limited, so that a predetermined attenuation amount can be ensured even at the maximum opening degree. The predetermined amount of attenuation will change according to the maximum opening of the check valve restricted by the restricting member, as long as it is determined according to the allowable noise volume. [0011] The restriction member may be provided on the side opposite to the valve seat through the valve body, and the valve body may protrude toward the discharge port more than the restriction member. [0012] According to this structure, since the valve body projects more toward the discharge port than the restricting member, it is possible to hinder the propagation of sound waves from the restricting member side toward the valve seat side through the valve body. Therefore, the sound wave is attenuated by this obstruction, and the sound reduction effect as a muffler can be improved. [0013] At least a part of the valve body may be disposed in a space where the communication hole and the discharge port are linearly connected. [0014] According to this structure, the sound wave from the expansion chamber inlet (communication hole) toward the expansion chamber outlet (exhaust port) will dry up with the valve body, so the sound reduction effect due to diffraction attenuation can be obtained more reliably. [0015] Viewed from the communication direction of the communication hole, the area of the valve body may not exceed 70% of the cross-sectional area of the expansion chamber. [0016] According to this structure, the valve body does not become a rigid wall on the sound, and the sound waves facing the valve body in the acoustic element and the sound waves reflected by the valve body can be prevented from resonating. Generally speaking, the larger the valve body, the more it will hinder the sound wave, and the larger the valve body, the greater the sound reduction effect. However, when the valve body is larger than a certain degree, the sound waves facing the valve body in the acoustic element and the sound waves reflected by the valve body may resonate. The present inventors have found that the above resonance occurs when the area of the valve body is 70% or more with respect to the sectional area of the expansion chamber. Therefore, by setting the area of the valve body to less than 70% of the cross-sectional area of the expansion chamber, the valve body can be prevented from functioning as a rigid wall, the amount of sound reflection in the valve body can be reduced, and resonance can be suppressed. In this way, it is possible to suppress a reduction in the sound reduction effect of a specific frequency. [0017] The acoustic element may include a resonance prevention structure in the induction chamber. [0018] According to this structure, the resonance in the acoustic element can be suppressed by the resonance prevention structure, and the reduction in the noise reduction effect at a specific frequency can be suppressed. Especially when the acoustic element has a resonance prevention structure, it is possible to suppress resonance in the acoustic element regardless of the shape of the valve body. Therefore, by providing the acoustic element with a resonance prevention structure, the valve body can be appropriately designed regardless of whether or not there is resonance. [Inventive Effect] [0019] According to the embodiment of the present invention, since the valve body of the check valve has a tapered portion, it is possible to provide a muffler having a check valve structure having both a counterflow suppression function and a muffler function.

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [0022] (First Embodiment) As shown in FIG. 1, the muffler 1 of this embodiment is used to attenuate sound waves that are propagated by overlapping with the compressed air flow discharged from the compressor 2. Therefore, the muffler 1 of this embodiment is disposed in the discharge flow path 4 of the compressor 2. [0023] As shown in FIG. 2, the muffler 1 includes an induction tube (acoustic element) 10 having a circular tube and a limited length extending in the direction of the axis L. The diameter of the muffler 1 is larger than that of the induction tube 10 as viewed from the axis L. A substantially circular tube-shaped expansion portion 20 and a connection portion 30 that fluidly connects the same. The induction tube 10, the expansion portion 20, and the connection portion 30 are formed of an integrated casing 3. In this embodiment, although the housing 3 is formed into a substantially circular tube shape, it may be formed into, for example, a polygonal tube shape. In addition, the induction tube 10, the expansion portion 20, and the connection portion 30 may be constituted by members of different individuals, respectively. [0024] The induction tube 10 defines an induction chamber 11 inside and is a circular tube for inducing compressed air discharged from the compressor 2 (see FIG. 1) to an expansion chamber 21 described later. [0025] The connection portion 30 includes a partition wall 31 for partitioning the induction chamber 11 and an expansion chamber 21 described later. The partition wall 31 of the present embodiment is a part of the casing 3 and is formed by projecting a part of the inner surface of the casing 3 toward the axis L. The partition wall 31 is provided with a circular communication hole 32 for communicating the induction chamber 11 and the expansion chamber 21. That is, the partition wall 31 of this embodiment is formed in a ring shape when viewed from the axis L direction. [0026] The expansion unit 20 defines an expansion chamber 21 inside and has a discharge port 22, and the discharge port 22 is provided to discharge the compressed air in a direction different from the axis L direction. In the present embodiment, although the discharge direction of the discharge port 22 is a direction orthogonal to the axis L, the discharge direction is not limited to this, and may be a direction inclined with respect to the axis L, for example. [0027] Further, in the expansion portion 20, a circular opening portion 23 is provided at an end portion opposite to the connection portion 30. The opening portion 23 is closed by a disc-shaped cover 24. When viewed from the axis L, the outer shape of the cover 24 is formed to be substantially the same as the outer shape of the case 3. The cover 24 is detachably attached to the case 3, and is attached to the case 3 by, for example, screwing. [0028] The cover body 24 is a valve body 25 that holds the communication hole 32 that can be closed by a spring (elastic member) 26. In the connection portion 30, a part of the partition wall 31 constitutes the valve seat 33. That is, the check valve 5 is constituted by the valve seat 33, the valve body 25, and the spring 26. The valve body 25 is urged toward the valve seat 33 by the spring 26, and abuts against the valve seat 33 to block the communication hole 32. [0029] The valve body 25 is provided with an annular tapered portion 25a, a circular flat plate portion 25b, and a recessed portion 25c. The tapered portion 25a is a portion provided on the peripheral edge portion and abutting against the valve seat 33, and has a direction facing the valve seat. The shape of the tapered portion 33 is such that the flat plate portion 25b is provided inside the tapered portion 25a, and the recessed portion 25c is provided on the side opposite to the surface facing the valve seat 33 (the surface on the cover body 24 side). Hereinafter, a surface on the valve seat 33 side of the two main surfaces of the valve body 25 is referred to as a surface, and a surface opposite to the surface facing the valve seat 33 (a surface on the lid body 24 side) is referred to as a back surface. That is, the recessed portion 25 c is provided on the back surface of the valve body 25. In this embodiment, the flat plate portion 25b and the tapered portion 25a have the same thickness, and the valve body 25 is a single plate. Therefore, the shape of the back side of the front surface of the valve body 25 is similar to the shape of the back surface. [0030] In addition, when viewed from the axis L, the communication hole 32 and the flat plate portion 25b, which are both circular, are provided concentrically, and the diameter of the communication hole 32 is formed to be larger than the diameter of the flat plate portion 25b. Therefore, even when the check valve 5 is closed, the flat plate portion 25b of the valve body 25 does not contact the valve seat 33, but the tapered portion 25a of the valve body 25 contacts the valve seat 33. [0031] In addition, when viewed from the direction of the axis L, the area of the valve body 25 in this embodiment is about 25% of the cross-sectional area of the expansion chamber 21. Preferably, the area of the valve body 25 is less than 70% of the cross-sectional area of the expansion chamber 21. When the area of the valve body 25 is less than 70% of the cross-sectional area of the expansion chamber 21, the valve body 25 does not become an acoustic rigid wall. In the induction chamber 11, the sound wave toward the valve body 25 and the valve body 25 can be suppressed. The reflected sound waves resonate. [0032] As shown in FIG. 3, generally speaking, the larger the valve body 25, the more the sound waves will be blocked, so the larger the valve body 25, the greater the volume reduction. However, when the valve body 25 is larger than a certain level, the sound waves toward the valve body 25 and the sound waves reflected by the valve body 25 in the induction chamber 11 will resonate, causing a reduction in the sound reduction effect at a specific frequency (see the figure Arrow in 3). The present inventors have found that the above resonance occurs when the area of the valve body 25 is 70% or more with respect to the cross-sectional area of the expansion chamber 21. Therefore, by setting the area of the valve body 25 to less than 70% of the cross-sectional area of the expansion chamber 21, the valve body 25 can be prevented from functioning as a rigid wall, and the amount of sound reflection at the valve body 25 can be reduced and suppressed The resonance. This makes it possible to suppress a reduction in the noise reduction effect at a specific frequency (see the arrow in FIG. 3). [0033] Next, the operation of the muffler 1 of the first embodiment obtained according to the above configuration will be described. [0034] Referring to FIGS. 1 and 2, when the compressor 2 is operated, the compressed air is discharged from the discharge port 2 a of the compressor 2 toward the discharge flow path 4, and flows into the muffler 1. The compressed air flowing into the muffler 1 flows in the induction chamber 11 in the induction tube 10 in the direction of the axis L toward the connection portion 30. Then, the compressed air passes through the communication hole 32 of the connection portion 30 and flows from the induction chamber 11 into the expansion chamber 21. When the compressed air flows into the expansion chamber 21, the check valve 5 must be opened. Comparing the pressure in the induction chamber 11 and the expansion chamber 21, when the pressure in the induction chamber 11 is higher than a certain level, the check valve 5 is opened, and in the opposite case, the check valve 5 is closed. Here, the pressure difference between the two chambers 11 and 21 for opening the check valve 5 is set to a desired pressure difference in accordance with the spring 26. When the check valve 5 is opened, the compressed air flowing into the expansion chamber 21 is curved in a direction orthogonal to the axis L, and is discharged from the discharge port 22 to the discharge flow path 4. [0035] The expansion section 20 forms a larger flow path cross section with respect to the induction tube 10 and the discharge port 22. That is, when the compressed air passes through the communication hole 32 and flows from the induction chamber 11 into the expansion chamber 21, the cross-sectional area of the flow path of the compressed air becomes large. In addition, when the compressed air is discharged from the expansion chamber 21 through the discharge port 22, the cross-sectional area of the flow path of the compressed air becomes small. Therefore, the impedance changes abruptly at these two places, and the sound waves are reflected internally and attenuated. Specifically, reflection occurs at the boundary between the induction chamber 11 and the expansion chamber 21 and at the boundary between the expansion chamber 21 and the discharge port 22, and the sound waves are attenuated. In this manner, the expansion chamber 21 is provided so that the cross-sectional area of the flow path is changed to attenuate the sound waves propagating by overlapping with the compressed air flow. [0036] According to this embodiment, it is possible to provide the muffler 1 having a check valve 5 having both a backflow suppression function and a muffler function, which can save space and obtain a higher muffler effect than in the past. Specifically, when the valve body 25 is in contact with the valve seat 33, the communication hole 32 is plugged by the tapered portion 25a, so that the communication hole 32 can be reliably plugged. If the valve body 25 does not have the tapered portion 25a, but the communication hole 32 is blocked by the flat plate portion 25b, due to the assembly tolerance or manufacturing tolerance of the flat plate portion 25b, it may not be able to reliably abut against the valve seat 33. That is, the communication hole 32 cannot be reliably plugged, and the function as the check valve 5 cannot be performed. According to the structure of this embodiment, this problem can be suppressed by the tapered portion 25a, and the backward flow of the compressed air can be stably suppressed. Here, the reverse flow means that the compressed air flows from the expansion chamber 21 to the induction chamber 11 through the communication hole 32. In addition, by making a part of the valve body 25 tapered, the rigidity of the valve body 25 can be improved, and the thickness of the plate in order to obtain the necessary flexural rigidity can be reduced. As a result, the valve body 25 can be made lighter than when it is simply flat, which contributes to cost reduction. In addition, the valve body 25 is in contact with the valve seat 33 at the tapered portion 25a. Compared with the case where the flat portion 25b is in contact with each other, the flow path of the compressed air is gradually widened, so that an increase in pressure loss can be suppressed. The check valve 5 is provided with a spring, and the check valve 5 is opened only when the pressure on the upstream side (the induction chamber 11 side) of the spring 26 is higher than the downstream side (the expansion chamber 21 side) by a certain degree or more. That is, the backflow suppression function can be easily realized by the spring 26. In addition, the valve body 25 has a recessed portion 25c on the back surface, and a sound wave overlapping with the compressed air passing through the communication hole 32 will be wound around the recessed portion 25c to cause a diffraction phenomenon. Therefore, the sound reduction effect caused by the diffraction attenuation of the sound wave can be obtained. In addition, since the surface of the holding valve body 25 is different from the surface having the discharge port 22, the valve body 25 can be accessed from outside the discharge port 22. Therefore, even when piping is provided below the discharge port 22, maintenance of the check valve 5 can be performed without removing the piping. In order to maintain the check valve 5 efficiently, it is preferable to provide the opening portion 23 other than the discharge port 22 in the expansion portion 20 as in this embodiment, and the check valve 5 can be externally connected from outside the discharge port 22. take. [0037] In addition, as in the first modification shown in FIG. 4, the valve body 25 may not be plate-shaped but block-shaped. That is, the thickness of the valve body 25 is not particularly limited. In this modification, similarly to the first embodiment, the shape on the back side of the surface of the valve body 25 is similar to the shape on the back side. [0038] In addition, as in the second modification shown in FIG. 5, the recessed portion 25c on the back surface of the valve body 25 may be a part of a spherical surface. That is, the aspect of the recessed portion 25c is not particularly limited as long as it is an aspect in which the above-mentioned diffraction attenuation can occur. [0039] (Second Embodiment) Fig. 6 is a schematic side sectional view of a muffler 1 according to a second embodiment. The structure of the muffler 1 of this embodiment other than the restricting member 27 is the same as that of the first embodiment of FIG. 2. Therefore, the same parts as those in the structure shown in FIG. 2 are assigned the same reference numerals and their descriptions are omitted. [0040] The muffler 1 of this embodiment further includes a restricting member 27 for restricting the opening degree of the check valve 5. The restriction member 27 is provided so as to surround the spring 26 when viewed from the axis L direction. The restriction member 27 is formed by protruding a part of the lid body 24 in a cylindrical shape with the axis L as the center. That is, the restriction member 27 is provided so as to be concentric with the communication hole 32. More specifically, the restricting member 27 is provided on the opposite side (the lid body 24 side) of the valve seat 33 with the valve body 25 interposed therebetween. The valve body 25 protrudes toward the discharge port 22 more than the restricting member 27. When the valve body 25 moves in a direction away from the valve seat 33 against the urging force of the spring 26, the back surface of the valve body 25 abuts against the restricting member 27, and the movement of the valve body 25 is restricted. When viewed from the direction of the axis L, the diameter of the restricting member 27 is smaller than the diameter of the tapered portion 25 a of the valve body 25. In addition, the length of the restricting member 27 is such that at least a part of the valve body 25 can be arranged in the space S connecting the communication hole 32 and the discharge port 22 linearly even if the check valve 5 is opened to the maximum extent. FIG. 6 shows the state when the check valve 5 is opened to the maximum extent. [0041] According to the present embodiment, the maximum opening degree of the check valve 5 can be restricted by the restricting member 27, and the noise reduction effect can be prevented from being significantly weakened. Specifically, when the opening degree of the check valve 5 increases, the sound waves that pass through the discharge port 22 without interfering with the valve body 25 increase, so that the amount of sound wave attenuation caused by the valve body 25 becomes small. That is, the closer the valve body 25 is to the position closer to the valve seat 33, the greater the noise reduction effect can be expected. In the present embodiment, the maximum opening degree of the check valve 5 is limited, so that a predetermined attenuation amount can be secured even at the maximum opening degree. The predetermined amount of attenuation will be changed according to the maximum opening degree of the check valve 5 restricted by the restricting member 27 as long as it is determined according to the allowable noise volume. [0042] Further, since the valve body 25 projects more toward the discharge port 22 than the restricting member 27, it is possible to hinder the propagation of sound waves from the restricting member 27 side to the valve seat 33 side via the valve body 25 (see the dotted arrow in FIG. 6) . Therefore, the sound wave is attenuated by this obstruction, and the sound reduction effect as the muffler 1 can be improved. In contrast, as in the comparative example shown in FIG. 7, the valve body 25 does not protrude toward the discharge port 22 than the restricting member 27, and cannot obstruct the restriction member 27 side through the valve body 25 as in the case of FIG. 6. The sound wave propagates toward the valve seat 33 side. Therefore, the sound reduction effect as the muffler 1 cannot be improved. [0043] In addition, even when the check valve 5 is opened to the maximum extent, at least a part of the valve body 25 can be arranged in the space S connecting the communication hole 32 and the discharge port 22 linearly, so that the valve body 25 will dry out from the expansion chamber. The sound wave at the entrance (communication hole 32) of 21 is directed toward the exit (exhaust opening 22) of the expansion chamber 21, and the sound reduction effect due to diffraction attenuation can be obtained more reliably. [0044] (Third Embodiment) Fig. 8 is a schematic side sectional view of a muffler 1 according to a third embodiment. The muffler 1 of this embodiment is the same as the second embodiment of FIG. 6 except that a structure other than the resonance prevention structure is provided in the induction chamber 11. Therefore, the same parts as those in the structure shown in FIG. 6 are assigned the same reference numerals, and descriptions thereof are omitted. [0045] In this embodiment, the sound absorbing material 12 is arranged in the induction chamber 11 as a resonance preventing structure. The sound absorbing material 12 is made of, for example, a porous material such as glass wool or mineral wool, and is attached to the inner surface of the induction tube 10. In addition, when the use environment is high temperature, a metal fiber material such as iron or stainless steel can also be used as the sound absorbing material 12. [0046] According to this embodiment, by providing the sound absorbing material 12 as a resonance preventing structure, it is possible to suppress resonance in the induction tube 10, and it is possible to suppress a reduction in the noise reduction effect at a specific frequency. This makes it possible to suppress resonance regardless of the shape of the valve body 25. Therefore, the valve body 25 can be appropriately designed regardless of the presence or absence of resonance. In this embodiment, the acoustic element is constituted by the induction tube 10 and the sound absorbing material 12. [0047] In addition, like the modification shown in FIG. 9, a plurality of wrinkled protrusions 13 may be provided as the resonance preventing structure instead of the sound absorbing material 12. The protruding portion 13 protrudes from the inner surface of the induction tube 10 toward the axis L. The protruding portion 13 has a shape in which a through hole is provided in the center of a circular flat plate when viewed from the axis L direction. In this modification, the acoustic element is constituted by the induction tube 10 including the protruding portion 13. [0048] The foregoing is a description of specific embodiments of the present invention and modifications thereof, but the present invention is not limited to the above forms, and can be implemented with various changes within the scope of the present invention. For example, the content of each embodiment can be appropriately combined as one embodiment of the present invention.

[0049]

1‧‧‧ Silencer

2‧‧‧compressor

2a‧‧‧Exhaust

3‧‧‧shell

4‧‧‧Exhaust flow path

5‧‧‧ check valve

10‧‧‧ induction tube (sound component)

11‧‧‧ induction room

12‧‧‧ sound-absorbing material (sound component)

13‧‧‧ protrusion (sound component)

20‧‧‧ Expansion

21‧‧‧Expansion chamber

22‧‧‧Exhaust

23‧‧‧ opening

24‧‧‧ Cover

25‧‧‧Valve body

25a‧‧‧Tapered

25b‧‧‧ Flat

25c‧‧‧Concave

26‧‧‧spring (spring member)

27‧‧‧ Restricted components

30‧‧‧Connecting Department

31‧‧‧partition

32‧‧‧ communication hole

33‧‧‧Valve seat

L‧‧‧ axis

[0020] FIG. 1 is a schematic configuration diagram of a device using a muffler according to a first embodiment of the present invention. FIG. 2 is a schematic side sectional view of the muffler according to the first embodiment of the present invention. FIG. 3 is a graph showing the sound reduction volume of the muffler of the first embodiment. FIG. 4 is a schematic side sectional view showing a first modification of the muffler of the first embodiment. FIG. 5 is a schematic side sectional view showing a second modification of the muffler of the first embodiment. FIG. 6 is a schematic side sectional view of a muffler according to a second embodiment. FIG. 7 is a schematic side sectional view showing a comparative example of the muffler of the second embodiment. Fig. 8 is a schematic side sectional view of a muffler according to a third embodiment. FIG. 9 is a schematic side sectional view showing a modification of the muffler according to the third embodiment.

Claims (6)

A muffler includes an expansion part having a discharge port and an expansion chamber defined therein, an acoustic element having a induction tube of a limited length defining an induction chamber therein, and an acoustic element for communicating the expansion chamber and the induction chamber. A connection portion of the communication hole and a check valve for preventing the fluid flowing from the induction chamber through the communication hole to the expansion chamber from flowing backward, the check valve includes a valve seat provided in the connection portion, and A valve body that abuts the valve seat and plugs the communication hole, and an elastic member that urges the valve body toward the valve seat. The valve system includes a tapered portion, a flat plate portion, and a recessed portion. The tapered portion is provided. The portion in contact with the valve seat at the peripheral edge portion has a shape that tapers toward the valve seat. The flat plate portion is provided inside the tapered portion. The recessed portion is provided on the opposite side of the surface facing the valve seat. surface. The silencer according to claim 1, further comprising: a restricting member that restricts a maximum opening degree of the check valve. The silencer according to claim 2, wherein: the restricting member is provided on the opposite side of the valve seat through the valve body, and the valve body protrudes toward the discharge port more than the restricting member. The muffler according to any one of claim 1 to claim 3, wherein at least a part of the valve body is arranged in a space where the communication hole and the discharge port are linearly connected. The muffler according to any one of claim 1 to claim 3, wherein: 观察 the area of the valve body does not reach 70% of the cross-sectional area of the expansion chamber when viewed from the communication direction of the communication hole. The muffler according to any one of claim 1 to claim 3, wherein the sound element has a resonance prevention structure in the induction room.