Sound insulating portion

Abstract

To provide a sound insulating part capable of attenuating sound in various frequency bands.SOLUTION: The sound insulating portion includes space forming portions 10 and 20 that form a transmission space S for transmitting a sound wave and have an introduction portion 12 for introducing the sound wave into the transmission space and a lead-out portion 13 for leading out the sound wave introduced into the transmission space to the outside of the transmission space, and a phase adjustment portion 30 that changes a phase of a part of the sound wave in the sound wave transmitted through the transmission space and attenuates a sound wave corresponding to a frequency of the sound wave whose phase is changed in the sound wave transmitted through the transmission space. The phase adjustment unit changes a frequency band of the sound wave whose phase is to be changed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sound insulation. [Background technology]

[0002] Conventionally, a silencer has been known that has a cylindrical member in which a first transmission region and a second transmission region through which sound is transmitted are formed (see, for example, Patent Document 1). The first transmission region is cylindrically formed and surrounded by the inner wall surface of the cylindrical member. The second transmission region is spirally formed inside the cylindrical member. The cylindrical member has openings on both one side and the other side in the axial direction that communicate with the first transmission region. Furthermore, the cylindrical member has an inlet opening on the upstream surface on one side in the axial direction that communicates with the second transmission region, and an outlet opening on the downstream surface on the other side in the axial direction that communicates with the second transmission region.

[0003] In the silencer described in Patent Document 1, sound waves introduced through an opening on one side of the cylindrical member in the axial direction pass through the first transmission region and exit from the opening on the other side of the axial direction. Sound waves introduced through an inlet opening formed on the upstream surface of the cylindrical member pass through the second transmission region and exit from the outlet opening formed on the downstream surface. The transmission distance of the first transmission region, surrounded by the inner wall surface of the cylindrical member, is different from the transmission distance of the spiral second transmission region formed inside the cylindrical member. The first and second transmission regions are formed so that the phases of the sound waves passing through the first transmission region and exiting from the other side of the axial direction are shifted from the phases of the sound waves passing through the second transmission region and exiting from the outlet opening. A silencer configured in this way attenuates sound by causing interference between sounds passing through the first transmission region and the second transmission region. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 11,846,217 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when noise is attenuated using a sound-insulating part such as the silencer of Patent Document 1, the noise may include a wide frequency range from low to high. However, when attenuating sound using the silencer described in Patent Document 1, the frequency range of sound that can be attenuated is uniquely determined based on the relationship between the transmission distance of the first transmission region and the transmission distance of the second transmission region. In other words, the silencer described in Patent Document 1 can only attenuate sound in a specific frequency range. For this reason, it is difficult to address noise that includes a variety of frequency ranges using a method of associating the configuration described in Patent Document 1 with a sound-insulating part.

[0006] In view of the above, an object of the present disclosure is to provide a sound-insulating part that can attenuate sounds in various frequency bands. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, The soundproofing section is a space forming section (10, 20, 60, 70, 100) that forms a transmission space (S) for transmitting sound waves and has an introduction section (12, 105) that introduces sound waves into the transmission space and an extraction section (13, 106) that extracts the sound waves introduced into the transmission space to the outside of the transmission space; a phase adjusting unit (30, 80, 100) that attenuates, among the sound waves propagating through the transmission space, sound waves corresponding to the frequency of the sound waves whose phases have been changed by changing the phase of some of the sound waves propagating through the transmission space; The phase adjustment unit changes the frequency band of the sound wave whose phase is to be changed.

[0008] According to this, the frequency band of sound waves that can be attenuated can be changed by the phase adjustment section, so that sounds in various frequency bands can be attenuated.

[0009] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a perspective view of the sound insulating part according to the first embodiment. [Figure 2] FIG. 2 is a perspective view of an inner cylindrical portion according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. [Figure 4] 5 is an explanatory diagram for explaining sound waves transmitted through a bypass groove according to the first embodiment. FIG. [Figure 5] 10 is an explanatory diagram illustrating sound waves transmitted through the bypass groove when the outer cylindrical portion is rotated. FIG. [Figure 6] 10 is an explanatory diagram for explaining a change in the frequency band of sound waves attenuated by a sound insulating portion that changes depending on the length of a detour route. FIG. [Figure 7] FIG. 10 is a perspective view of a sound insulating part according to a second embodiment. [Figure 8] 10 is an explanatory view illustrating a restricting protrusion according to a second embodiment. FIG. [Figure 9] 10 is an explanatory diagram for explaining sound waves transmitted through a bypass groove according to a second embodiment. FIG. [Figure 10] FIG. 10 is a perspective view of a sound insulating part according to a third embodiment. [Figure 11] 10 is an explanatory diagram for explaining sound waves transmitted through a bypass groove according to a third embodiment. FIG. [Figure 12] FIG. 10 is a perspective view of a sound insulating part according to a fourth embodiment. [Figure 13] FIG. 10 is a perspective view of a bypass pipe according to a fourth embodiment. [Figure 14] FIG. 10 is an explanatory diagram for explaining a change in the length of a detour route according to the fourth embodiment. [Figure 15] 10 is an explanatory diagram for explaining the length of a detour route when the first cylindrical portion is rotated. FIG. [Figure 16] FIG. 11 is a cross-sectional view of a sound insulating part according to a fifth embodiment. [Figure 17] FIG. 17 is an enlarged view of part XVII in FIG. [Figure 18] FIG. 10 is a cross-sectional view of a sound insulating part according to a sixth embodiment. [Figure 19] FIG. 13 is a cross-sectional view of a sound insulating part according to a seventh embodiment. [Figure 20] FIG. 13 is a cross-sectional view of a sound insulating part according to a modified example of the seventh embodiment. [Figure 21] FIG. 13 is a perspective view of a sound insulating part according to an eighth embodiment. [Figure 22] FIG. 13 is an explanatory diagram for explaining the frequency band of sound waves attenuated by a sound insulating portion according to the eighth embodiment. [Figure 23] FIG. 13 is a cross-sectional view of a sound-proofing part according to a ninth embodiment. [Figure 24] FIG. 10 is an explanatory diagram for explaining the length of the detour route when the detour route section is moved. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the preceding embodiments will be given the same reference numerals, and their description may be omitted. Furthermore, in the embodiments, when only some of the components are described, the components described in the preceding embodiments can be applied to the remaining components. The following embodiments can be partially combined with each other, even if not specifically stated, as long as there is no particular problem with the combination.

[0012] (First embodiment) The sound insulating part 1 of this embodiment will be described with reference to Figs. 1 to 6. In this embodiment, an example in which the sound insulating part 1 is applied to a vehicle will be described. The sound insulating part 1 is attached to a vehicle part that generates noise when it operates, such as an electric compressor. The sound insulating part 1 is capable of attenuating the volume of the noise generated by the vehicle part when it operates. When the sound insulating part 1 is attached to an electric compressor, the sound insulating part 1 may be attached to, for example, a refrigerant pipe through which a refrigerant flows.

[0013] The sound insulating part 1 is made of, for example, resin. The sound insulating part 1 of this embodiment is made of nylon resin. Note that the material of the sound insulating part 1 is not limited to nylon resin. The sound insulating part 1 may be made of a resin other than nylon resin, or may be made of a material other than resin, such as metal.

[0014] As shown in Fig. 1, the sound-insulating part 1 of this embodiment is configured by combining two cylindrical members extending along a predetermined axial direction. Specifically, the sound-insulating part 1 has a hollow cylindrical inner cylindrical part 10 and a hollow cylindrical outer cylindrical part 20 having an outer diameter larger than that of the inner cylindrical part 10, and is configured by fitting the inner cylindrical part 10 inside the outer cylindrical part 20. The inner cylindrical part 10 and the outer cylindrical part 20 are formed so that their axes are coaxial. The sound-insulating part 1 is configured so that sound waves can be introduced to the inner peripheral side of the inner cylindrical part 10. Hereinafter, the axes of the inner cylindrical part 10 and the outer cylindrical part 20 will also be referred to as the axis CL of the sound-insulating part 1.

[0015] As shown in FIG. 1 and other figures, the direction in which the axis CL of the sound-insulating unit 1 extends is referred to as the axial direction D1, the direction around the axis CL is referred to as the circumferential direction D2, and the direction extending radially from the axis CL is referred to as the radial direction D3. The radial direction D3 is perpendicular to the axial direction D1. Furthermore, within the axial direction D1, the direction along which sound waves are introduced to the inner periphery of the inner cylindrical unit 10 and transmitted is referred to as the transmission direction D1a, and the direction opposite to the transmission direction D1a is referred to as the reverse transmission direction D1b. The sound-insulating unit 1 attenuates sound introduced from the end of the inner cylindrical unit 10 on the reverse transmission direction D1b side. In FIG. 1, sound waves introduced into the sound-insulating unit 1 are indicated by outline arrows.

[0016] The inner cylindrical portion 10 and the outer cylindrical portion 20 extend along the axial direction D1 and are formed to have the same size in the axial direction D1. The outer cylindrical portion 20 is disposed radially outward of the inner cylindrical portion 10 in the radial direction D3. The inner diameter of the outer cylindrical portion 20 is slightly larger than the outer diameter of the inner cylindrical portion 10, allowing the inner cylindrical portion 10 to be fitted inside. When the inner cylindrical portion 10 is fitted inside the outer cylindrical portion 20, the outer cylindrical portion 20 can rotate in the circumferential direction D2 by an externally applied force. However, when the inner cylindrical portion 10 is fitted inside the outer cylindrical portion 20, there is a configuration in which there is almost no gap between the outer cylindrical portion 20 and the inner cylindrical portion 10 so that almost no sound waves are introduced between the outer cylindrical portion 20 and the inner cylindrical portion 10.

[0017] As shown in Fig. 2, the inner cylindrical portion 10 has an inner outer wall portion 11 that forms the outer wall of the inner cylindrical portion 10. The inner outer wall portion 11 has an inner outer peripheral surface 111 on the outside in the radial direction D3, and an inner inner peripheral surface 112 on the inside in the radial direction D3. The inner outer wall portion 11 has a constant dimension from the inner outer peripheral surface 111 to the inner inner peripheral surface 112. The inner outer peripheral surface 111 faces the outer cylindrical portion 20 in the radial direction D3. The inner inner peripheral surface 112 forms a transmission space S inside the inner cylindrical portion 10 through which sound waves are transmitted, and surrounds the transmission space S.

[0018] Furthermore, the inner outer wall portion 11 has, at its end on the reverse transmission direction D1b side, an introduction opening 12 for introducing sound waves into the transmission space S, and, at its end on the transmission direction D1a side, an outlet opening 13 for guiding the sound waves introduced into the transmission space S to the outside of the transmission space S. The introduction opening 12 and the outlet opening 13 open toward the external space, which is the space outside the sound-insulating portion 1, and communicate with the transmission space S. In this embodiment, the introduction opening 12 corresponds to the introduction portion, and the outlet opening 13 corresponds to the outlet portion.

[0019] Two through holes 14 and two suppression protrusions 15 are formed in the inner outer wall portion 11. The two through holes 14 penetrate the inner outer wall portion 11 along the radial direction D3 from the inner outer peripheral surface 111 to the inner inner peripheral surface 112. The two through holes 14 are spaced apart from each other in the axial direction D1 and have the same inner diameter. Hereinafter, of the two through holes 14, the one closer to the introduction opening 12 will be referred to as the inlet-side through hole 141, and the one farther from the introduction opening 12 will be referred to as the outlet-side through hole 142. The inlet-side through hole 141 and the outlet-side through hole 142 are aligned along the axial direction D1. The inlet-side through hole 141 and the outlet-side through hole 142 are connected to the bypass groove 30, which will be described later.

[0020] The two suppression protrusions 15 are provided at positions where the two through holes 14 are formed. The two suppression protrusions 15 are semi-cylindrical and protrude outward in the radial direction D3 from the inner outer peripheral surface 111. That is, the two suppression protrusions 15 are arc-shaped when viewed in a direction perpendicular to the radial direction D3. One side of each of the two suppression protrusions 15 surrounds approximately half of the circumference of the inlet-side through hole 141, and the other side surrounds approximately half of the circumference of the outlet-side through hole 142. Hereinafter, of the two suppression protrusions 15, the side closer to the introduction opening 12 and surrounding the inlet-side through hole 141 will be referred to as the inlet-side protrusion 151, and the side farther from the introduction opening 12 and surrounding the outlet-side through hole 142 will be referred to as the outlet-side protrusion 152.

[0021] As shown in FIG. 1 , the outer cylindrical portion 20 has an outer outer wall portion 21 that forms the outer wall of the outer cylindrical portion 20. The outer outer wall portion 21 has an outer outer peripheral surface 211 on the outside in the radial direction D3 and an outer inner peripheral surface 212 on the inside in the radial direction D3. The outer outer wall portion 21 has a constant dimension from the outer outer peripheral surface 211 to the outer inner peripheral surface 212, which is larger than the dimension from the inner outer peripheral surface 111 to the inner inner peripheral surface 112 of the inner outer wall portion 11. The outer inner peripheral surface 212 faces the inner inner peripheral surface 112 and abuts against the inner inner peripheral surface 112. The inner cylindrical portion 10 and the outer cylindrical portion 20 are integrally formed with the outer inner peripheral surface 212 abutting against the inner inner peripheral surface 112 to form a transmission space S. The inner cylindrical portion 10 and the outer cylindrical portion 20 correspond to space-forming portions that form the transmission space S.

[0022] 1 and 3, a bypass groove 30 is formed on the outer inner circumferential surface 212 of the outer outer wall portion 21, through which a portion of the sound waves introduced into the transmission space S is guided. The bypass groove 30 is recessed outward in the radial direction D3 from the outer inner circumferential surface 212. The bypass groove 30 includes an inlet-side bypass groove 31 that can face the inlet-side through hole 141, an outlet-side bypass groove 32 that can face the outlet-side through hole 142, and a connecting bypass groove 33 that connects the inlet-side bypass groove 31 and the outlet-side bypass groove 32. The inlet-side bypass groove 31, the outlet-side bypass groove 32, and the connecting bypass groove 33 are formed as a single continuous groove. When the outer cylindrical portion 20 is fitted into the inner cylindrical portion 10, the inlet-side detour groove 31, the outlet-side detour groove 32, and the connecting detour groove 33 face the inner outer peripheral surface 111 of the inner cylindrical portion 10, and are thereby covered and closed by the inner outer peripheral surface 111. In other words, the detour groove 30, which is made up of the inlet-side detour groove 31, the outlet-side detour groove 32, and the connecting detour groove 33, is formed inside the inner cylindrical portion 10 and the outer cylindrical portion 20. Note that in FIG. 1, a portion of the outer cylindrical portion 20 is shown see-through, and the detour groove 30 is indicated by a dashed line.

[0023] The inlet-side detour groove 31 and the outlet-side detour groove 32 have a groove shape extending in the circumferential direction D2 and are formed along the outer inner circumferential surface 212. The inlet-side detour groove 31 and the outlet-side detour groove 32 are formed side by side along the axial direction D1 at a predetermined interval. The inlet-side detour groove 31 and the outlet-side detour groove 32 are formed to have the same dimension in the circumferential direction D2. In this embodiment, the size of the inlet-side detour groove 31 and the outlet-side detour groove 32 in the circumferential direction D2 is approximately one-third of the inner diameter of the outer cylindrical portion 20. However, the size of the inlet-side detour groove 31 and the outlet-side detour groove 32 in the circumferential direction D2 is not limited and can be appropriately adjusted so as not to extend over the entire circumference of the outer inner circumferential surface 212. The inlet-side detour groove 31 and the outlet-side detour groove 32 may be formed to have different dimensions in the circumferential direction D2.

[0024] The inlet-side bypass groove 31 is formed closer to the reverse transmission direction D1b than the outlet-side bypass groove 32, and is formed at a position facing the inlet-side through hole 141 in the radial direction D3 when the outer cylindrical portion 20 is fitted to the inner cylindrical portion 10. That is, the inlet-side bypass groove 31 is formed at the same position in the axial direction D1 as the inlet-side through hole 141. One end of the inlet-side bypass groove 31 in the circumferential direction D2 is blocked by the outer outer wall portion 21, and the other end in the circumferential direction D2 is connected to the connecting bypass groove 33. An inlet-side protrusion 151 is fitted inside the inlet-side bypass groove 31. Hereinafter, the one end of the inlet-side bypass groove 31 in the circumferential direction D2 will be referred to as an inlet-side blocked end 311.

[0025] The size of the inlet-side protrusion 151 in the radial direction D3 is approximately the same as the size of the inlet-side detour groove 31 in the radial direction D3, i.e., the depth of the inlet-side detour groove 31. The semi-cylindrical inlet-side protrusion 151 in the axial direction D1 is approximately the same as the size of the inlet-side detour groove 31 in the axial direction D1, i.e., the width of the groove-shaped inlet-side detour groove 31. However, the size of the inlet-side protrusion 151 in the radial direction D3 is slightly smaller than the depth of the inlet-side detour groove 31, and the size of the inlet-side protrusion 151 in the axial direction D1 is slightly smaller than the width of the inlet-side detour groove 31, so as not to impede rotation of the outer cylindrical portion 20 in the circumferential direction D2. The semi-cylindrical inlet-side protrusion 151 is formed so that the inner circumferential surface faces the connecting detour groove 33.

[0026] The outlet-side bypass groove 32 is formed closer to the transmission direction D1a than the inlet-side bypass groove 31, and is formed at a position facing the outlet-side through hole 142 in the radial direction D3 when the outer cylindrical portion 20 is fitted to the inner cylindrical portion 10. That is, the outlet-side bypass groove 32 is formed at the same position in the axial direction D1 as the outlet-side through hole 142, and is formed at a position farther from the introduction opening 12 than the inlet-side bypass groove 31. One end of the outlet-side bypass groove 32 in the circumferential direction D2 is blocked by the outer outer wall portion 21, and the other end of the outlet-side bypass groove 32 in the circumferential direction D2 is connected to the connecting bypass groove 33. An outlet-side protrusion 152 is fitted inside the outlet-side bypass groove 32. Hereinafter, one end of the outlet-side bypass groove 32 in the circumferential direction D2 will be referred to as an outlet-side blocked end 321.

[0027] The size of the outlet-side protrusion 152 in the radial direction D3 is approximately the same as the size of the outlet-side detour groove 32 in the radial direction D3, i.e., the depth of the outlet-side detour groove 32. The semi-cylindrical outlet-side protrusion 152 has a size in the axial direction D1 that is approximately the same as the size of the outlet-side detour groove 32 in the axial direction D1, i.e., the width of the groove-shaped outlet-side detour groove 32. However, so as not to impede rotation of the outer cylindrical portion 20 in the circumferential direction D2, the size of the outlet-side protrusion 152 in the radial direction D3 is slightly smaller than the depth of the outlet-side detour groove 32, and the size in the axial direction D1 is slightly smaller than the width of the outlet-side detour groove 32. The semi-cylindrical outlet-side protrusion 152 is formed so that the inner circumferential surface faces the connecting detour groove 33.

[0028] The connection detour groove 33 has a groove shape extending along the axial direction D1 and is formed along the outer inner circumferential surface 212. The size of the connection detour groove 33 in the axial direction D1 is equal to the distance between the inlet-side detour groove 31 and the outlet-side detour groove 32 in the axial direction D1. For example, in this embodiment, the size of the connection detour groove 33 in the axial direction D1 is approximately half the size of the outer cylindrical portion 20 in the axial direction D1. The end of the connection detour groove 33 on the reverse transmission direction D1b side is connected to the inlet-side detour groove 31, and the end of the connection detour groove 33 on the transmission direction D1a side is connected to the outlet-side detour groove 32. Therefore, the inlet-side detour groove 31 and the outlet-side detour groove 32 are communicated with each other via the connection detour groove 33. The size of the connection detour groove 33 in the axial direction D1 is not limited to approximately half the size of the outer cylindrical portion 20, but is appropriately adjusted depending on the distance between the inlet-side detour groove 31 and the outlet-side detour groove 32 in the axial direction D1.

[0029] The inlet-side bypass groove 31, the outlet-side bypass groove 32, and the connecting bypass groove 33 are connected to form a single groove, and the bypass groove 30 communicates with the transmission space S via the inlet-side through hole 141 and the outlet-side through hole 142. The inlet-side through hole 141, which is formed closer to the introduction opening 12 than the outlet-side through hole 142, connects the transmission space S with the inlet-side bypass groove 31, thereby guiding sound waves introduced into the transmission space S to the inlet-side bypass groove 31. The outlet-side through hole 142 connects the outlet-side bypass groove 32 with the transmission space S, thereby guiding sound waves introduced into the outlet-side bypass groove 32 via the inlet-side bypass groove 31 and the connecting bypass groove 33 to the transmission space S. In this embodiment, the inlet-side through hole 141 corresponds to the inlet portion, and the outlet-side through hole 142 corresponds to the outlet portion.

[0030] Therefore, the bypass groove 30 allows a portion of the sound waves introduced into the transmission space S through the introduction opening 12 to bypass part of the transmission space S and guide them to the outlet opening 13, thereby allowing them to be guided to the outside of the sound-insulating part 1. Specifically, the bypass groove 30 forms a bypass path that bypasses part of the transmission space S by introducing a portion of the sound waves introduced into the transmission space S from the entrance-side through hole 141, passing through the bypass groove 30, and guiding the sound waves from the exit-side through hole 142 to the transmission space S. The sound waves introduced into the bypass groove 30 from the entrance-side through hole 141 are transmitted in this order through the entrance-side bypass groove 31, the connecting bypass groove 33, and the exit-side bypass groove 32, as shown by the arrows in FIG. 4 , and are then guided to the exit-side through hole 142 and returned to the transmission space S.

[0031] Furthermore, the inlet-side bypass groove 31 is provided with a semi-cylindrical inlet-side protrusion 151 that surrounds approximately half of the circumference of the inlet-side through hole 141 and is formed so that its inner circumferential surface faces the connecting detour groove 33. As a result, sound waves introduced from the inlet-side through hole 141 into the inlet-side bypass groove 31 are prevented from being transmitted from the inlet-side protrusion 151 toward the inlet-side closed end 311, and transmission to the connecting detour groove 33 is promoted. Furthermore, the outlet-side bypass groove 32 is provided with a semi-cylindrical outlet-side protrusion 152 that surrounds approximately half of the circumference of the outlet-side through hole 142 and is formed so that its inner circumferential surface faces the connecting detour groove 33. As a result, sound waves introduced into the outlet-side bypass groove 32 are prevented from being transmitted from the outlet-side protrusion 152 toward the outlet-side closed end 321, and transmission from the outlet-side through hole 142 to the transmission space S is promoted.

[0032] 5 , the portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 changes as the outer cylindrical portion 20 rotates in the circumferential direction D2. Furthermore, the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 can be changed as the outer cylindrical portion 20 rotates in the circumferential direction D2. The portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 and the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 change, thereby changing the transmission distance of the sound waves from the inlet-side through hole 141 to the outlet-side through hole 142. In other words, the relative positions of the outer cylindrical portion 20 and the inner cylindrical portion 10 in the circumferential direction D2 change, so the detour groove 30 can change the distance of the detour path that bypasses part of the transmission space S. Hereinafter, the length of the detour groove 30 from the inlet-side through-hole 141 to the outlet-side through-hole 142 will be referred to as the detour length.

[0033] In this embodiment, the detour length increases as the outer cylindrical portion 20 rotates and the portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 approaches the inlet-side blocked end 311, and as the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 approaches the outlet-side blocked end 321. That is, the detour length increases as the outer cylindrical portion 20 rotates to one side in the circumferential direction D2 and the inlet-side through hole 141 and the outlet-side through hole 142 move farther away from the connecting detour groove 33. When the outer cylindrical portion 20 rotates to one side in the circumferential direction D2 to a position where the inlet-side protrusion 151 and the outlet-side protrusion 152 contact the outer outer wall portion 21, the detour length becomes maximum.

[0034] Furthermore, as the outer cylindrical portion 20 rotates, the portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 and the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 approach the connecting detour groove 33, and the shorter the detour length becomes. That is, as the outer cylindrical portion 20 rotates to the other side in the circumferential direction D2, the inlet-side through hole 141 and the outlet-side through hole 142 approach the connecting detour groove 33, and the shorter the detour length becomes. When the outer cylindrical portion 20 rotates to the other side in the circumferential direction D2 to a position where the inlet-side through hole 141 and the outlet-side through hole 142 face the connecting detour groove 33, the detour length becomes minimum.

[0035] In the sound insulating part 1 of this embodiment, the outer cylindrical part 20 is rotatable in the circumferential direction D2 by an externally applied force. However, in the sound insulating part 1, the inner cylindrical part 10 may be rotatable in the circumferential direction D2 by an externally applied force, and the rotation of the inner cylindrical part 10 in the circumferential direction D2 may change the relative positions of the outer cylindrical part 20 and the inner cylindrical part 10 in the circumferential direction D2.

[0036] Next, the reason why the bypass groove 30 is formed in the sound insulation part 1 of this embodiment will be explained. When operating noise from a vehicle part is generated near the sound insulation part 1, sound waves accompanying the operating noise are introduced into the sound insulation part 1 from the introduction opening 12 formed at the end of the inner cylindrical part 10 on the side of the reverse transmission direction D1b. The sound waves introduced from the introduction opening 12 are then transmitted in the transmission direction D1a within the transmission space S and are discharged from the discharge opening 13 formed at the end of the inner cylindrical part 10 on the side of the transmission direction D1a.

[0037] As described above, in the sound insulating part 1 of this embodiment, the bypass groove 30 is formed between the inner outer peripheral surface 111 and the outer inner peripheral surface 212, and the inner outer wall part 11 is formed with the inlet-side through hole 141 and the outlet-side through hole 142 that connect the transmission space S to the bypass groove 30. Therefore, a portion of the sound waves introduced into the transmission space S is introduced from the inlet-side through hole 141 into the bypass groove 30 and returned from the outlet-side through hole 142 to the transmission space S. The bypass groove 30 has the inlet-side bypass groove 31 and the outlet-side bypass groove 32 that are formed along the circumferential direction D2.

[0038] For this reason, sound waves that propagate through the detour groove 30 travel a longer distance within the sound-insulating part 1 than when they propagate through the transmission space S without propagating through the detour groove 30. That is, the transmission distances of sound waves propagated through the sound-insulating part 1 differ between sound waves propagated only through the transmission space S and sound waves propagated through the transmission space S and the detour groove 30. For this reason, the sound-insulating part 1 can change the phase of the sound waves introduced into the detour groove 30 by propagating a portion of the sound waves introduced into the transmission space S through the detour groove 30. The detour groove 30 corresponds to a phase adjustment part that changes the phase of a portion of the sound waves introduced into the transmission space S.

[0039] When a phase mismatch occurs between the sound waves transmitted only through the transmission space S and the sound waves transmitted through the transmission space S and the detour groove 30, the sound waves transmitted only through the transmission space S interfere with the sound waves returned to the transmission space S via the detour groove 30. As a result, the sound-insulating unit 1 can attenuate the intensity of sound waves in a specific frequency band, among the sound waves transmitted within the transmission space S, that corresponds to the frequency band of the sound waves transmitted through the detour groove 30. Therefore, the sound-insulating unit 1 can attenuate sound that corresponds to this specific frequency band, among sounds generated in the vicinity of the sound-insulating unit 1. Furthermore, when the phase of the sound waves transmitted only through the transmission space S and the phase of the sound waves transmitted through the detour groove 30 are in opposite phase, the sound-insulating unit 1 can more greatly attenuate sound that corresponds to the frequency band of the sound waves transmitted through the detour groove 30.

[0040] For this reason, the detour groove 30 of the present embodiment changes the phase of the sound waves that have passed through the detour groove 30 so that the phase of the sound waves that have passed through the detour groove 30 and been transmitted to the outlet-side through hole 142 approaches the opposite phase of the sound waves that have passed through the detour groove 30 and been transmitted to the outlet-side through hole 142 without passing through the detour groove 30. Here, the amount of shift between the phase of the sound waves that have passed through the detour groove 30 and been transmitted to the outlet-side through hole 142 and the phase of the sound waves that have been transmitted to the outlet-side through hole 142 without passing through the detour groove 30 is defined as a phase shift amount Δφ. The detour groove 30 is configured to be able to change the phase of the sound waves that have passed through the detour groove 30 so as to satisfy the following mathematical formula 1.

[0041] (Number 1) +150+(N×360)≦Δφ≦+210+(N×360) Furthermore, as described above, if the phase of the sound waves that have passed through the bypass groove 30 and been transmitted to the outlet-side through-hole 142 is the opposite phase to the phase of the sound waves that have been transmitted to the outlet-side through-hole 142 without passing through the bypass groove 30, the sound insulating part 1 can attenuate the sound more significantly. For this reason, it is more desirable that the bypass groove 30 of this embodiment be configured so as to be able to change the phase of the sound waves that have passed through the bypass groove 30 so as to satisfy the following mathematical formula 2. Note that N in mathematical formulas 1 and 2 is an integer used as an arbitrary coefficient.

[0042] (Number 2) Δφ=±180+(N×360) The frequency band that is attenuated in sound waves transmitted only through the transmission space S changes depending on the detour length. Specifically, the frequency band that is attenuated by interference with sound waves returned to the transmission space S via the detour groove 30 becomes lower as the detour length becomes longer, and becomes higher as the detour length becomes shorter. Therefore, the longer the detour length, the lower the frequency band of sound waves that can attenuate the intensity of sound waves transmitted within the transmission space S. Also, the shorter the detour length, the higher the frequency band of sound waves that can attenuate the intensity of sound waves transmitted within the transmission space S. In other words, the frequency band of sound waves whose phase is changed by being introduced into the detour groove 30 can be changed depending on the detour length.

[0043] As described above, the length of the detour path varies depending on the relative positions in the circumferential direction D2 between the outer cylindrical portion 20 and the inner cylindrical portion 10. Therefore, by rotating the outer cylindrical portion 20 in the circumferential direction D2, the frequency band of sound attenuated by the sound-insulating portion 1 can be changed.

[0044] The change in the frequency band attenuated by the sound insulating unit 1 depending on the length of the detour path will be described with reference to Fig. 6. The solid line in Fig. 6 indicates the amount of sound attenuation by the sound insulating unit 1 when the rotational position of the outer cylindrical unit 20 is set to the position shown in Fig. 4. The dashed line in Fig. 6 indicates the amount of sound attenuation by the sound insulating unit 1 when the rotational position of the outer cylindrical unit 20 is set to the position shown in Fig. 5. As shown in Figs. 4 and 5, the length of the detour path when the outer cylindrical unit 20 is set to the position shown in Fig. 4 is longer than the length of the detour path when the outer cylindrical unit 20 is set to the position shown in Fig. 5.

[0045] Therefore, by rotating the outer cylindrical portion 20 to one side in the circumferential direction D2 so as to increase the length of the detour path, the frequency band of sound that the sound insulating unit 1 can attenuate can be lowered, as shown in Fig. 6. On the other hand, by rotating the outer cylindrical portion 20 to the other side in the circumferential direction D2 so as to decrease the length of the detour path, the frequency band of sound that the sound insulating unit 1 can attenuate can be increased. Furthermore, by adjusting the rotational position of the outer cylindrical portion 20 so that the phase of the sound waves transmitted only through the transmission space S and the phase of the sound waves transmitted through the detour groove 30 are opposite in phase, the sound insulating unit 1 can more significantly attenuate sound in the frequency band corresponding to the length of the detour path.

[0046] As described above, the sound-insulating part 1 of this embodiment comprises an inner cylindrical part 10 and an outer cylindrical part 20 which form a transmission space S for transmitting sound waves, and which have an inlet opening 12 for introducing sound waves into the transmission space S and an outlet opening 13 for guiding the sound waves introduced into the transmission space S to the outside of the transmission space S, and a detour groove 30 which changes the phase of some of the sound waves that are transmitted through the transmission space S, and attenuates sound waves that correspond to the frequency of the sound waves whose phases are changed, among the sound waves that are transmitted through the transmission space S. The detour groove 30 changes the frequency band of the sound waves whose phases are changed.

[0047] As a result, the bypass groove 30 can change the frequency band of sound waves that the sound-insulating part 1 can attenuate, so that sounds of various frequency bands that are emitted from the transmission space S to the outside through the outlet opening 13 can be attenuated.

[0048] Furthermore, according to the above embodiment, the following effects can be obtained.

[0049] (1) In the above embodiment, the bypass groove 30, which guides a portion of the sound waves introduced from the introduction opening 12 into the transmission space S to the extraction opening 13 by bypassing a portion of the transmission space S, is capable of changing the bypass length from the inlet-side through hole 141 to the outlet-side through hole 142. This makes it possible to realize a configuration in which the bypass groove 30 allows the bypass length to be changed.

[0050] (2) In the above embodiment, the detour groove 30 is formed inside the inner cylindrical portion 10 and the outer cylindrical portion 20. This simplifies the configuration of the sound-insulating portion 1 compared to a configuration in which a separate detour path is provided outside the inner cylindrical portion 10 and the outer cylindrical portion 20.

[0051] (3) In the above embodiment, the sound-insulating unit 1 includes an inner cylindrical portion 10 that extends along the axial direction D1 and is formed in a hollow cylindrical shape to form a transmission space S. The sound-insulating unit 1 further includes an outer cylindrical portion 20 that extends along the axial direction D1 and is disposed outside the inner cylindrical portion 10 to surround the outer periphery of the inner cylindrical portion 10. The inner cylindrical portion 10 has an inner outer peripheral surface 111 that faces the outer cylindrical portion 20, an inner inner peripheral surface 112 that surrounds the transmission space S, and an inlet-side through hole 141 and an outlet-side through hole 142 that are formed through the inner outer wall portion 11 and are spaced a predetermined distance apart in the axial direction D1. The outer cylindrical portion 20 faces the inner outer peripheral surface 111 and has an outer inner peripheral surface 212 that abuts against the inner outer peripheral surface 111, and is rotatable in the circumferential direction D2. The detour groove 30 is formed in the shape of a groove at a position opposite the inlet side through hole 141 and the outlet side through hole 142 on the outer inner surface 212, and the detour length changes depending on the change in the relative position of the inner cylindrical portion 10 and the outer cylindrical portion 20 in the circumferential direction D2.

[0052] According to this, by changing the relative position between the outer cylindrical portion 20 and the inner cylindrical portion 10, the frequency band of sounds that can be attenuated can be changed.

[0053] (Modification of the first embodiment) In the first embodiment described above, an example has been described in which one inlet-side through hole 141 and one outlet-side through hole 142 are formed in the inner cylindrical portion 10, but this is not limiting. For example, a plurality of inlet-side through holes 141 and a plurality of outlet-side through holes 142 may be formed. In this case, the additional hole may be formed in a position facing either the inlet-side detour groove 31 or the outlet-side detour groove 32. Alternatively, the shape of the detour groove 30 can be changed depending on the position of the additional hole, and a groove extending in the circumferential direction D2 may be added in a position facing the additional hole.

[0054] (Second embodiment) Next, a second embodiment will be described with reference to Figures 7 to 9. In this embodiment, the shapes of the bypass groove 30 and the suppression protrusion 15 are different from those of the first embodiment. Other than this, the second embodiment is similar to the first embodiment. Therefore, in this embodiment, differences from the first embodiment will be mainly described, and descriptions of similar parts to the first embodiment may be omitted.

[0055] As shown in FIG. 7 , the detour groove 30 of this embodiment has two connecting detour grooves 33 connecting the inlet-side detour groove 31 and the outlet-side detour groove 32. That is, the detour groove 30 of this embodiment has the inlet-side detour groove 31, the outlet-side detour groove 32, and two connecting detour grooves 33. The inlet-side detour groove 31, the outlet-side detour groove 32, and the two connecting detour grooves 33 are formed as a single continuous groove. Hereinafter, of the two connecting detour grooves 33, one side in the circumferential direction D2 will be referred to as the first connecting detour groove 331, and the other side in the circumferential direction D2 will be referred to as the second connecting detour groove 332. Note that FIG. 7 shows a portion of the outer cylindrical portion 20 as a see-through view, and the inlet-side detour groove 31, the outlet-side detour groove 32, the first connecting detour groove 331, and the second connecting detour groove 332 are indicated by dashed lines. Moreover, the inlet side bypass groove 31 and the outlet side bypass groove 32 have the same shape and configuration as those in the first embodiment, and therefore detailed description thereof will be omitted.

[0056] The first connection detour groove 331 and the second connection detour groove 332 have a groove shape extending in the axial direction D1 and are formed along the outer inner circumferential surface 212. The first connection detour groove 331 and the second connection detour groove 332 are formed side by side in the circumferential direction D2 at a predetermined interval. The first connection detour groove 331 and the second connection detour groove 332 have the same dimension in the axial direction D1, and each dimension in the axial direction D1 is equal to the distance between the inlet-side detour groove 31 and the outlet-side detour groove 32.

[0057] Furthermore, the first connecting detour groove 331 and the second connecting detour groove 332 have their respective ends on the reverse transmission direction D1b side connected to the inlet-side detour groove 31, and their respective ends on the transmission direction D1a side connected to the outlet-side detour groove 32. Therefore, the inlet-side detour groove 31 and the outlet-side detour groove 32 are connected at their ends on one side in the circumferential direction D2 via the first connecting detour groove 331. Furthermore, the inlet-side detour groove 31 and the outlet-side detour groove 32 are connected at their ends on the other side in the circumferential direction D2 via the second connecting detour groove 332. Therefore, the inlet-side detour groove 31 and the outlet-side detour groove 32 of this embodiment have their ends on one side in the circumferential direction D2 that are not blocked by the outer outer wall portion 21. The detour groove 30 is formed in an annular shape.

[0058] 8, unlike the first embodiment, the suppression protrusion 15 of this embodiment is formed in a thin plate shape having a plate surface in the circumferential direction D2. That is, the suppression protrusion 15 has a rectangular shape extending in the axial direction D1 when viewed in a direction perpendicular to the radial direction D3. The suppression protrusion 15 is formed to protrude outward in the radial direction D3 from the inner outer peripheral surface 111. Hereinafter, of the two suppression protrusions 15, the one closer to the introduction opening 12 will be referred to as the inlet-side branch portion 153, and the one farther from the introduction opening 12 will be referred to as the outlet-side branch portion 154.

[0059] The inlet-side branch portion 153 passes through the center of the inlet-side through hole 141 and is provided across the opening of the inlet-side through hole 141. However, the size of the inlet-side branch portion 153 in the plate thickness direction is formed to be smaller than the inner diameter of the inlet-side through hole 141 so as not to block the opening of the inlet-side through hole 141. The inlet-side branch portion 153 divides the opening of the inlet-side through hole 141 into two. Therefore, the opening of the inlet-side through hole 141 is divided by the inlet-side branch portion 153 into a first connection detour groove 331 side and a second connection detour groove 332 side.

[0060] The size of the inlet-side branch portion 153 in the radial direction D3 is approximately the same as the depth of the inlet-side detour groove 31, and the size of the inlet-side branch portion 153 in the axial direction D1 is approximately the same as the width of the inlet-side detour groove 31. Furthermore, the size of the inlet-side branch portion 153 in the axial direction D1 is slightly smaller than the width of the inlet-side detour groove 31 so as not to impede rotation of the outer cylindrical portion 20 in the circumferential direction D2. The inlet-side branch portion 153 is formed so that one plate surface in the circumferential direction D2 faces the first connection detour groove 331, and the other plate surface in the circumferential direction D2 faces the second connection detour groove 332.

[0061] The outlet-side branch portion 154 passes through the center of the outlet-side through hole 142 and is provided across the opening of the outlet-side through hole 142. However, the size of the outlet-side branch portion 154 in the plate thickness direction is formed to be smaller than the outlet-side through hole 142 so as not to block the opening of the outlet-side through hole 142. The outlet-side branch portion 154 divides the opening of the outlet-side through hole 142 into two. Therefore, the opening of the outlet-side through hole 142 is divided by the outlet-side branch portion 154 into a first connection detour groove 331 side and a second connection detour groove 332 side.

[0062] The size of the outlet-side branch portion 154 in the radial direction D3 is approximately the same as the depth of the outlet-side detour groove 32, and the size of the outlet-side branch portion 154 in the axial direction D1 is approximately the same as the width of the outlet-side detour groove 32. Furthermore, the size of the outlet-side branch portion 154 in the axial direction D1 is slightly smaller than the width of the outlet-side detour groove 32 so as not to impede rotation of the outer cylindrical portion 20 in the circumferential direction D2. The outlet-side branch portion 154 is formed so that one plate surface in the circumferential direction D2 faces the first connection detour groove 331, and the other plate surface in the circumferential direction D2 faces the second connection detour groove 332.

[0063] The bypass groove 30 of this embodiment formed in this manner communicates with the transmission space S via the inlet-side through hole 141 and the outlet-side through hole 142. Therefore, the bypass groove 30 makes it possible for a portion of the sound waves introduced into the transmission space S through the introduction opening 12 to bypass a portion of the transmission space S and be guided to the outlet opening 13, thereby allowing the sound waves to be guided to the outside of the sound-insulating part 1. Specifically, the bypass groove 30 forms a bypass path that bypasses a portion of the transmission space S by introducing a portion of the sound waves introduced into the transmission space S from the inlet-side through hole 141, passing through the bypass groove 30, and guiding the sound waves to the transmission space S from the outlet-side through hole 142.

[0064] Here, the inlet-side detour groove 31 of this embodiment is provided with an inlet-side branch portion 153 that divides the opening portion of the inlet-side through hole 141 into one side and the other side in the circumferential direction D2. Therefore, sound waves introduced from the inlet-side through hole 141 into the inlet-side detour groove 31 are branched and transmitted to one side and the other side in the circumferential direction D2 by the inlet-side branch portion 153, as shown by the arrows in FIG. 9 . Then, the sound waves transmitted to one side in the circumferential direction D2 from the inlet-side branch portion 153 are transmitted from one side in the circumferential direction D2 to the outlet-side detour groove 32 via the first connecting detour groove 331. Meanwhile, the sound waves transmitted to the other side in the circumferential direction D2 from the inlet-side branch portion 153 are transmitted from the other side in the circumferential direction D2 to the outlet-side detour groove 32 via the second connecting detour groove 332.

[0065] The outlet-side bypass groove 32 is provided with an outlet-side branch portion 154 that divides the opening of the outlet-side through hole 142 into one side and the other side in the circumferential direction D2. Therefore, sound waves introduced into the outlet-side bypass groove 32 from one side in the circumferential direction D2 via the first connecting bypass groove 331 are led out of the outlet-side through hole 142 in a state separated from sound waves introduced into the outlet-side bypass groove 32 from the other side in the circumferential direction D2 via the second connecting bypass groove 332.

[0066] Therefore, the bypass groove 30 of the present embodiment forms a bypass path that branches a portion of the sound waves introduced into the inside of the sound insulating part 1 to one side and the other side in the circumferential direction D2, thereby bypassing a portion of the transmission space S. Then, as shown in Fig. 9 , the sound waves transmitted from the inlet-side through hole 141 to one side in the circumferential direction D2 are transmitted in this order through the inlet-side bypass groove 31, the first connecting bypass groove 331, and the outlet-side bypass groove 32, and are then guided to the outlet-side through hole 142 and returned to the transmission space S. Meanwhile, the sound waves transmitted from the inlet-side through hole 141 to the other side in the circumferential direction D2 are transmitted in this order through the inlet-side bypass groove 31, the second connecting bypass groove 332, and the outlet-side bypass groove 32, and are then guided to the outlet-side through hole 142 and returned to the transmission space S. The inlet side bypass groove 31, the first connecting bypass groove 331, and the outlet side bypass groove 32 correspond to one side groove portion, and the inlet side bypass groove 31, the second connecting bypass groove 332, and the outlet side bypass groove 32 correspond to the other side groove portion.

[0067] As a result, the sound waves transmitted within the transmission space S are attenuated in intensity corresponding to the frequency band of the sound waves returned to the transmission space S via the first connection bypass groove 331 and in intensity corresponding to the frequency band of the sound waves returned to the transmission space S via the second connection bypass groove 332.

[0068] Furthermore, when the outer cylindrical portion 20 rotates in the circumferential direction D2, the bypass groove 30 can change the transmission distance of the sound waves that are guided from the outlet-side through hole 142 via the first connecting bypass groove 331 and the transmission distance of the sound waves that are guided from the outlet-side through hole 142 via the second connecting bypass groove 332. In other words, the bypass groove 30 can change the distances of two bypass paths that bypass part of the transmission space S by changing the relative positions of the outer cylindrical portion 20 and the inner cylindrical portion 10 in the circumferential direction D2. Hereinafter, of the length of the bypass groove 30 from the inlet-side through hole 141 to the outlet-side through hole 142, the length that passes through the first connecting bypass groove 331 will be referred to as the first bypass length, and the length that passes through the second connecting bypass groove 332 will be referred to as the second bypass length.

[0069] In this embodiment, as the outer cylindrical portion 20 rotates, the first detour length decreases as the portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 approaches the first connecting detour groove 331 and the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 approaches the second connecting detour groove 332. That is, the more the outer cylindrical portion 20 rotates toward one side in the circumferential direction D2, the shorter the first detour length. Furthermore, the more the outer cylindrical portion 20 rotates toward one side in the circumferential direction D2, the longer the second detour length. Furthermore, when the outer cylindrical portion 20 rotates in the circumferential direction D2 to a position where the inlet-side branch portion 153 and the outlet-side branch portion 154 face the first connecting detour groove 331, the first detour length becomes minimum and the second detour length becomes maximum.

[0070] Furthermore, as the outer cylindrical portion 20 rotates, the first detour length increases as the portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 and the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 approach the second connection detour groove 332. That is, the more the outer cylindrical portion 20 rotates toward the other side in the circumferential direction D2, the shorter the first detour length. Furthermore, the more the outer cylindrical portion 20 rotates toward the other side in the circumferential direction D2, the shorter the second detour length. Furthermore, when the outer cylindrical portion 20 rotates in the circumferential direction D2 to a position where the inlet-side through hole 141 and the outlet-side through hole 142 face the second connection detour groove 332, the first detour length becomes maximum and the second detour length becomes minimum. The sound-insulating unit 1 can change the frequency band of sound waves, the phase of which is changed by being introduced into the detour groove 30, depending on the first detour length and the second detour length.

[0071] Therefore, by rotating the outer cylindrical portion 20 in the circumferential direction D2, it is possible to change the frequency bands of sound that can be attenuated by each of the first connection detour groove 331 and the second connection detour groove 332. Specifically, by rotating the outer cylindrical portion 20 to one side in the circumferential direction D2 to shorten the length of the first detour path, it is possible to raise the frequency band of sound that corresponds to the first detour path length, among the frequency bands of sound that can be attenuated by the sound insulation unit 1. Furthermore, by rotating the outer cylindrical portion 20 to one side in the circumferential direction D2 to lengthen the length of the second detour path, it is possible to lower the frequency band of sound that corresponds to the second detour path length, among the frequency bands of sound that can be attenuated by the sound insulation unit 1.

[0072] In contrast to this, by rotating the outer cylindrical portion 20 to the other side in the circumferential direction D2 and lengthening the length of the first detour route, it is possible to lower the frequency band of sound that corresponds to the first detour route length, among the frequency band of sound that can be attenuated by the sound insulation unit 1. Furthermore, by rotating the outer cylindrical portion 20 to the other side in the circumferential direction D2 and shortening the length of the second detour route, it is possible to raise the frequency band of sound that corresponds to the second detour route length, among the frequency band of sound that can be attenuated by the sound insulation unit 1.

[0073] As described above, the detour groove 30 has the inlet-side detour groove 31, the first connecting detour groove 331, and the outlet-side detour groove 32, which transmit the sound waves transmitted from the inlet-side through hole 141 to the detour groove 30 to one side in the circumferential direction D2 and guide them to the outlet-side through hole 142. The detour groove 30 also has the inlet-side detour groove 31, the second connecting detour groove 332, and the outlet-side detour groove 32, which transmit the sound waves transmitted from the inlet-side through hole 141 to the detour groove 30 to the other side in the circumferential direction D2 and guide them to the outlet-side through hole 142.

[0074] This allows the sound insulation part 1 to reduce the frequency band of sound corresponding to the first detour length and attenuate the frequency band of sound corresponding to the second detour length. Furthermore, by rotating the outer cylindrical part 20 in the circumferential direction D2, the detour grooves 30 can change the frequency band of sound waves that the sound insulation part 1 can attenuate, so that sounds of various frequency bands that are guided from the transmission space S to the outside through the guide opening 13 can be attenuated.

[0075] (Third embodiment) Next, a third embodiment will be described with reference to Figures 10 and 11. In this embodiment, the configuration of the inner cylindrical portion 10 differs from that of the second embodiment. The rest of the third embodiment is the same as that of the second embodiment. Therefore, in this embodiment, differences from the second embodiment will be mainly described, and descriptions of the same parts as the second embodiment may be omitted.

[0076] As shown in FIG. 10 , the inner cylindrical portion 10 of this embodiment is configured by two cylindrical members arranged side by side in the axial direction D1. Specifically, the inner cylindrical portion 10 is configured by a first inner cylindrical portion 40 arranged on the reverse transmission direction D1b side of the axial direction D1 and a second inner cylindrical portion 50 arranged on the transmission direction D1a side, which are connected in the axial direction D1. That is, the inner cylindrical portion 10 of this embodiment is divided into the first inner cylindrical portion 40 and the second inner cylindrical portion 50. The inner cylindrical portion 10 of this embodiment is divided at approximately the center in the axial direction D1. The first inner cylindrical portion 40 and the second inner cylindrical portion 50 have the same size in the axial direction D1. The first inner cylindrical portion 40 and the second inner cylindrical portion 50 correspond to divided inner cylindrical portions.

[0077] An inlet-side through hole 141 is formed in the first inner cylindrical portion 40. The inlet-side through hole 141 is formed in approximately the center of the first inner cylindrical portion 40 in the axial direction D1. An outlet-side through hole 142 is formed in the second inner cylindrical portion 50. The outlet-side through hole 142 is formed in approximately the center of the second inner cylindrical portion 50 in the axial direction D1.

[0078] Furthermore, when the outer cylindrical portion 20 is fitted onto the outside, the first inner cylindrical portion 40 and the second inner cylindrical portion 50 are rotatable in the circumferential direction D2 by an externally applied force. That is, in the sound-insulating unit 1, the relative position in the circumferential direction D2 between the outer cylindrical portion 20 and the first inner cylindrical portion 40 is changeable by the rotation of the first inner cylindrical portion 40 in the circumferential direction D2. In addition, in the sound-insulating unit 1, the relative position in the circumferential direction D2 between the outer cylindrical portion 20 and the second inner cylindrical portion 50 is changeable by the rotation of the second inner cylindrical portion 50 in the circumferential direction D2.

[0079] Here, the first inner cylindrical portion 40 and the second inner cylindrical portion 50 are rotatable in one direction and the other direction in the circumferential direction D2 independently of each other. For example, when one of the first inner cylindrical portion 40 and the second inner cylindrical portion 50 rotates in one direction in the circumferential direction D2 due to an externally applied force, the other can rotate in the other direction in the circumferential direction D2. Furthermore, when one of the first inner cylindrical portion 40 and the second inner cylindrical portion 50 rotates in the circumferential direction D2 due to an externally applied force, the other can maintain a state in which it does not rotate. Therefore, in the inner cylindrical portion 10 of this embodiment, as shown in FIG. 10 , the inlet-side through hole 141 and the outlet-side through hole 142 can be arranged not to be aligned in the axial direction D1.

[0080] In the present embodiment in which the inner cylindrical portion 10 is formed in this manner, as shown in Fig. 11 , sound waves introduced from the inlet-side through hole 141 into the inlet-side detour groove 31 are transmitted to the outlet-side detour groove 32 via the first connecting detour groove 331. Furthermore, sound waves introduced from the inlet-side through hole 141 into the inlet-side detour groove 31 are transmitted to the outlet-side detour groove 32 via the second connecting detour groove 332. In the present embodiment in which the inner cylindrical portion 10 is formed by the first inner cylindrical portion 40 and the second inner cylindrical portion 50 in this manner, the first detour path length and the second detour path length can be changed by rotating the first inner cylindrical portion 40 and the second inner cylindrical portion 50.

[0081] Specifically, as the first inner cylindrical portion 40 rotates, the length of the first detour route becomes smaller, and the length of the second detour route becomes larger, as the portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 approaches the first connecting detour groove 331. That is, as the first inner cylindrical portion 40 rotates toward one side in the circumferential direction D2, the length of the first detour route becomes smaller, and the length of the second detour route becomes larger. Also, as the first inner cylindrical portion 40 rotates, the portion of the inlet-side detour groove 31 facing the inlet-side through hole 141 approaches the second connecting detour groove 332, the length of the first detour route becomes larger, and the length of the second detour route becomes smaller. That is, as the first inner cylindrical portion 40 rotates toward the other side in the circumferential direction D2, the length of the first detour route becomes larger, and the length of the second detour route becomes smaller.

[0082] As the second inner cylindrical portion 50 rotates and the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 approaches the first connecting detour groove 331, the first detour length becomes shorter, and the second detour length becomes longer. That is, as the second inner cylindrical portion 50 rotates toward one side in the circumferential direction D2, the first detour length becomes shorter and the second detour length becomes longer. Also, as the second inner cylindrical portion 50 rotates and the portion of the outlet-side detour groove 32 facing the outlet-side through hole 142 approaches the second connecting detour groove 332, the first detour length becomes longer and the second detour length becomes shorter. That is, as the second inner cylindrical portion 50 rotates toward the other side in the circumferential direction D2, the first detour length becomes longer and the second detour length becomes shorter.

[0083] Therefore, by rotating the first inner cylindrical portion 40 and the second inner cylindrical portion 50 in the circumferential direction D2, it is possible to change the frequency bands of sound that can be attenuated by the first connection detour groove 331 and the second connection detour groove 332, respectively. Specifically, by rotating at least one of the first inner cylindrical portion 40 and the second inner cylindrical portion 50 to one side in the circumferential direction D2, it is possible to increase the frequency band of sound that corresponds to the first detour length, among the frequency bands of sound that can be attenuated by the sound insulation unit 1. Furthermore, by rotating at least one of the first inner cylindrical portion 40 and the second inner cylindrical portion 50 to one side in the circumferential direction D2, it is possible to lower the frequency band of sound that corresponds to the second detour length, among the frequency bands of sound that can be attenuated by the sound insulation unit 1.

[0084] In contrast to this, by rotating at least one of the first inner cylindrical portion 40 and the second inner cylindrical portion 50 to the other side in the circumferential direction D2, it is possible to lower the frequency band of sound that corresponds to the first detour length among the frequency band of sound that can be attenuated by the sound insulation unit 1. Furthermore, by rotating at least one of the first inner cylindrical portion 40 and the second inner cylindrical portion 50 to the other side in the circumferential direction D2, it is possible to raise the frequency band of sound that corresponds to the second detour length among the frequency band of sound that can be attenuated by the sound insulation unit 1.

[0085] As described above, the inner cylindrical portion 10 has the first inner cylindrical portion 40, in which the inlet-side through-hole 141 is formed, and the second inner cylindrical portion 50, in which the outlet-side through-hole 142 is formed, aligned in the axial direction D1. The first inner cylindrical portion 40 and the second inner cylindrical portion 50 are rotatable in the circumferential direction D2 independently of each other.

[0086] This allows the sound insulating unit 1 to reduce the frequency band of sound corresponding to the first detour length and attenuate the frequency band of sound corresponding to the second detour length. Furthermore, the frequency band of sound waves that the sound insulating unit 1 can attenuate can be changed by rotating the outer cylindrical portion 20 in the circumferential direction D2 using the detour grooves 30, so that sounds of various frequency bands that are guided from the transmission space S to the outside through the guide opening 13 can be attenuated. Furthermore, the first detour length and the second detour length can be more easily adjusted than when the sound insulating unit 1 is not configured with the first inner cylindrical portion 40 and the second inner cylindrical portion 50.

[0087] (Modification of the third embodiment) In the above-described third embodiment, an example has been described in which the inner cylindrical portion 10 is divided into two portions, the first inner cylindrical portion 40 and the second inner cylindrical portion 50, but the present invention is not limited to this. For example, the inner cylindrical portion 10 may be divided into three or more cylindrical members, and a hole corresponding to either the inlet-side through-hole 141 or the outlet-side through-hole 142 may be formed in each of the divided cylindrical members.

[0088] (Fourth embodiment) Next, a fourth embodiment will be described with reference to Figs. 12 to 14. In this embodiment, the configuration of the sound insulating part 1 is different from that of the first embodiment. Other than this, the fourth embodiment is similar to the first embodiment. Therefore, in this embodiment, the differences from the first embodiment will be mainly described, and a description of the same parts as the first embodiment may be omitted.

[0089] The sound-insulating unit 1 of this embodiment is configured by combining two cylindrical members extending along a predetermined axial direction. Specifically, the sound-insulating unit 1 has a hollow cylindrical first cylindrical portion 60 and a second cylindrical portion 70 disposed inside the first cylindrical portion 60. The sound-insulating unit 1 is configured by fitting the second cylindrical portion 70 inside the first cylindrical portion 60 from the transmission direction D1a toward the reverse transmission direction D1b. In the sound-insulating unit 1, the first cylindrical portion 60 and the second cylindrical portion 70 each form a transmission space S, and sound waves can be introduced into the inner circumferential side of each. In addition, a detouring pipe 80 (described below) is provided inside the sound-insulating unit 1, which detouring a portion of the sound waves introduced into the inner circumferential side of each of the first cylindrical portion 60 and the second cylindrical portion 70. The first cylindrical portion 60 and the second cylindrical portion 70 correspond to space-forming portions that form the transmission space S. In addition, the first cylindrical portion 60 corresponds to a first forming portion that forms the transmission space S. The second cylindrical portion 70 corresponds to a second forming portion that forms the transmission space S.

[0090] The first cylindrical portion 60 and the second cylindrical portion 70 extend along the axial direction D1 and are formed to have the same size in the axial direction D1. The first cylindrical portion 60 has a larger outer diameter than the second cylindrical portion 70 and a smaller inner diameter than the second cylindrical portion 70. The first cylindrical portion 60 has a hollow shape with a bottomed cylindrical surface on the transmission direction D1a side that opens toward the reverse transmission direction D1b side. This bottomed cylindrical opening has a shape corresponding to the second cylindrical portion 70. The second cylindrical portion 70 can be inserted into the bottomed cylindrical opening of the first cylindrical portion 60 from the transmission direction D1a side. When the second cylindrical portion 70 is inserted, the first cylindrical portion 60 can rotate in the circumferential direction D2 by an externally applied force.

[0091] The first cylindrical portion 60 has an introduction opening 12 at its end on the side of the reverse transmission direction D1b, which introduces sound waves into the transmission space S. Furthermore, a first bypass pipe 81, which is part of a bypass pipe 80 described below, is provided inside the first cylindrical portion 60, and an inlet opening 62 communicating with the bypass pipe 80 is formed on a first inner circumferential surface 61 on the inside in the radial direction D3. The first inner circumferential surface 61 forms the transmission space S through which sound waves are transmitted inside the first cylindrical portion 60. Details of the first bypass pipe 81 and the inlet opening 62 will be described later. In FIG. 12, the first bypass pipe 81 is indicated by a dashed line.

[0092] The second cylindrical portion 70 has an outer diameter smaller than that of the first cylindrical portion 60 and an inner diameter larger than that of the first cylindrical portion 60. The second cylindrical portion 70 has a hollow cylindrical shape with a surface on the reverse transmission direction D1b side that opens toward the transmission direction D1a side. The second cylindrical portion 70 also has an outlet opening 13 at its end on the transmission direction D1a side, which allows sound waves introduced into the transmission space S to be guided to the outside. The second cylindrical portion 70 also has a second bypass pipe 82 (described later) that is part of the bypass pipe 80, and an outlet opening 72 communicating with the second bypass pipe 82 is formed on a second inner circumferential surface 71 on the inside in the radial direction D3. The second inner circumferential surface 71 forms the transmission space S through which sound waves are transmitted inside the second cylindrical portion 70. The outlet opening 72 is located farther from the introduction opening 12 than the inlet opening 62. In FIG. 12 , the second bypass pipe 82 is indicated by a two-dot chain line.

[0093] The first cylindrical portion 60 has a first detour pipe 81 shown in FIGS. 12 and 13 into which a portion of the sound waves introduced into the transmission space S from the introduction opening 12 is introduced. As shown in FIG. 13, the first detour pipe 81 is arranged around the axis CL of the sound insulating portion 1 formed by combining the first cylindrical portion 60 and the second cylindrical portion 70, and is formed in a spiral shape extending in the axial direction D1. The first detour pipe 81 is made of, for example, resin. Note that the first detour pipe 81 may be made of a material other than resin, such as metal.

[0094] The first bypass pipe 81 has a constant outer diameter along the axial direction D1. Furthermore, the first bypass pipe 81 has a constant pitch in the axial direction D1 each time it rotates in the circumferential direction D2 around the axis CL of the sound insulating part 1. The first bypass pipe 81 has a hollow shape, and sound waves can be transmitted through the inside. That is, the first bypass pipe 81 has a tubular shape, and forms a path through which sound waves are transmitted.

[0095] The first bypass pipe 81 has an end on the reverse transmission direction D1b side that communicates with the inlet opening 62. The first bypass pipe 81 has an end on the transmission direction D1a side that is inserted into the second bypass pipe 82. The first bypass pipe 81 is rotatable integrally with the first cylindrical portion 60 as the first cylindrical portion 60 rotates in the circumferential direction D2.

[0096] The second cylindrical portion 70 has a second detour pipe 82 shown in FIG. 13 into which a portion of the sound waves introduced into the transmission space S from the introduction opening 12 is introduced. As shown in FIG. 13, the second detour pipe 82 is arranged around the axis CL of the sound insulator 1 and is formed in a spiral shape extending in the axial direction D1. The second detour pipe 82 is formed, for example, from the same resin as the first detour pipe 81. Note that the second detour pipe 82 may be formed, for example, from a different material from the first detour pipe 81, or may be formed from a material other than resin, such as metal.

[0097] The second bypass pipe 82 has a constant outer diameter along the axial direction D1. Furthermore, the second bypass pipe 82 has a constant pitch in the axial direction D1 for each rotation in the circumferential direction D2 about the axis CL of the sound insulating part 1. The pitch of the second cylindrical part 70 is equal to the pitch of the first bypass pipe 81. The second bypass pipe 82 has a hollow shape, and sound waves can be transmitted inside. In other words, the second bypass pipe 82 is tubular, and forms a path through which sound waves are transmitted.

[0098] The second bypass pipe 82 has an end portion on the transmission direction D1a side that communicates with the outlet opening 72. The second bypass pipe 82 of this embodiment has an inner diameter that is slightly larger than the outer diameter of the first bypass pipe 81, allowing the first bypass pipe 81 to be inserted therein. In this embodiment, the first bypass pipe 81 is inserted into the second bypass pipe 82 from the end portion on the reverse transmission direction D1b side of the second bypass pipe 82, and the path formed by the first bypass pipe 81 and the path formed by the second bypass pipe 82 communicate with each other. The configuration in which the first bypass pipe 81 is inserted into the second bypass pipe 82 forms a bypass pipe 80 that bypasses a portion of the sound waves introduced into the transmission space S. In FIG. 13 , the portion of the first bypass pipe 81 that is inserted inside the second bypass pipe 82 is indicated by a dashed line.

[0099] The opening surfaces of the inlet opening 62 and the outlet opening 72 intersect with the radial direction D3. In other words, the opening surfaces of the inlet opening 62 and the outlet opening 72 intersect with the direction that extends radially from the axis of the transmission space S. Specifically, the first inner circumferential surface 61 has a surface that surrounds the inlet opening 62 that is either recessed or protruded relative to other portions. The opening surface that forms the inlet opening 62 is inclined with respect to a straight line that extends from the axis center CL toward the first inner circumferential surface 61 in the radial direction D3.

[0100] The second inner circumferential surface 71 has a surface that surrounds the outlet opening 72 that is either recessed or protruded relative to other portions. The opening surface that forms the outlet opening 72 is inclined with respect to a straight line that extends from the axis CL toward the second inner circumferential surface 71 in the radial direction D3.

[0101] The directions in which the opening planes of the inlet opening 62 and the outlet opening 72 intersect with the radial direction D3 may be the same or different. For example, the inlet opening 62 and the outlet opening 72 may intersect with the radial direction D3 so that their opening planes face the introduction opening 12, or they may intersect with the radial direction D3 so that their opening planes face the discharge opening 13. Alternatively, the inlet opening 62 and the outlet opening 72 may intersect with the radial direction D3 so that their opening planes face neither the introduction opening 12 nor the discharge opening 13.

[0102] The bypass pipe 80 is also in communication with the transmission space S via the inlet opening 62 and the outlet opening 72. The inlet opening 62, which is formed at a position closer to the introduction opening 12 than the outlet opening 72, connects the transmission space S with the first bypass pipe 81, thereby guiding the sound waves introduced into the transmission space S to the first bypass pipe 81. The outlet opening 72 connects the second bypass pipe 82 with the transmission space S, thereby guiding the sound waves introduced into the second bypass pipe 82 via the inlet opening 62 and the first bypass pipe 81 to the transmission space S.

[0103] For this reason, the bypass pipe 80 makes it possible for a portion of the sound waves introduced into the transmission space S through the introduction opening 12 to bypass a portion of the transmission space S and guide them to the outlet opening 13, thereby enabling them to be guided to the outside of the sound-insulating part 1. Specifically, the bypass pipe 80 forms a bypass path that bypasses a portion of the transmission space S by introducing a portion of the sound waves introduced into the transmission space S from the inlet opening 62, passing through the bypass pipe 80, and guiding the sound waves to the transmission space S from the outlet opening 72. The sound waves introduced into the bypass pipe 80 from the inlet opening 62 are transmitted in this order through the first bypass pipe 81 and the second bypass pipe 82, and are guided to the outlet opening 72 and returned to the transmission space S.

[0104] Therefore, the sound waves transmitted within the transmission space S are attenuated in intensity corresponding to the frequency band of the sound waves returned to the transmission space S via the first bypass pipe 81 and the second bypass pipe 82. The bypass pipe 80 of this embodiment corresponds to a phase adjustment unit that changes the phase of some of the sound waves introduced into the transmission space S.

[0105] Furthermore, the first bypass pipe 81 of the bypass pipe 80 rotates integrally with the first cylindrical portion 60 in the circumferential direction D2, thereby making it possible to increase or decrease the portion of the first bypass pipe 81 that is inserted into the second bypass pipe 82. That is, the first bypass pipe 81 of the bypass pipe 80 rotates integrally with the first cylindrical portion 60 in the circumferential direction D2, thereby changing the relative positions of the first bypass pipe 81 and the second bypass pipe 82 in the axial direction D1, making it possible to increase or decrease the amount of insertion of the first bypass pipe 81 into the second bypass pipe 82.

[0106] The transmission distance of sound waves from the inlet opening 62 to the outlet opening 72 can be changed by increasing or decreasing the portion of the first bypass pipe 81 that is inserted inside the second bypass pipe 82. In other words, the bypass pipe 80 can change the distance of the bypass path that bypasses part of the transmission space S by changing the relative position in the axial direction D1 between the first bypass pipe 81 and the second bypass pipe 82. Hereinafter, the length of the bypass pipe 80 from the inlet opening 62 to the outlet opening 72 in this embodiment will be referred to as the bypass path length.

[0107] 14, the more the first cylindrical portion 60 rotates in the circumferential direction D2 and the greater the portion of the first bypass pipe 81 that is inserted into the second bypass pipe 82, the shorter the bypass length becomes. In other words, the more the first cylindrical portion 60 rotates in the circumferential direction D2 so that the end of the first bypass pipe 81 on the transmission direction D1a side is inserted toward the end of the second bypass pipe 82 on the transmission direction D1a side, the shorter the bypass length becomes.

[0108] 15, the more the first cylindrical portion 60 rotates and the smaller the portion of the first bypass pipe 81 that is inserted into the second bypass pipe 82, the larger the bypass length becomes. In other words, the more the first cylindrical portion 60 rotates in the circumferential direction D2 so that the inserted portion of the first bypass pipe 81 on the transmission direction D1a side is gradually removed from the end of the second bypass pipe 82 on the reverse transmission direction D1b side, the larger the bypass length becomes.

[0109] Therefore, by rotating the first cylindrical portion 60 in the circumferential direction D2, it is possible to change the frequency band of sound that can be attenuated by the bypass pipe 80. Specifically, by rotating the first cylindrical portion 60 to shorten the bypass length, it is possible to raise the frequency band of sound that corresponds to the bypass length, among the frequency band of sound that can be attenuated by the sound insulation unit 1. On the other hand, by rotating the first cylindrical portion 60 to lengthen the bypass length, it is possible to lower the frequency band of sound that corresponds to the bypass length, among the frequency band of sound that can be attenuated by the sound insulation unit 1.

[0110] As described above, the sound-insulating unit 1 has the first cylindrical portion 60 and the second cylindrical portion 70, each extending along the axial direction D1 and forming the transmission space S. The detour pipe 80 includes a hollow first detour pipe 81 provided in the first cylindrical portion 60 and a hollow second detour pipe 82 provided in the second cylindrical portion 70. One side of the first detour pipe 81 communicates with the inlet opening 62, and the other side is inserted into and communicates with the second detour pipe 82. One side of the second detour pipe 82 communicates with the outlet opening 72, and the other side communicates with the first detour pipe 81. The detour lengths of the first detour pipe 81 and the second detour pipe 82 change as the first cylindrical portion 60 rotates in the circumferential direction D2, changing the relative positions of the first cylindrical portion 60 and the second cylindrical portion 70 in the axial direction D1.

[0111] This makes it possible to change the frequency band of sound that can be attenuated by changing the relative positions in the axial direction D1 between the first cylindrical portion 60 and the second cylindrical portion 70. Therefore, it is possible to attenuate sounds of various frequency bands that are output from the transmission space S to the outside through the output opening 13.

[0112] (Modification of the fourth embodiment) In the above-described fourth embodiment, an example has been described in which the first cylindrical portion 60 is rotatable in the circumferential direction D2 by an externally applied force, but the present invention is not limited to this. For example, the second cylindrical portion 70 may be rotatable in the circumferential direction D2 by an externally applied force. In this case, the bypass pipe 80 may be configured so that the second bypass pipe 82 can be inserted into the first bypass pipe 81.

[0113] (Fifth embodiment) Next, a fifth embodiment will be described with reference to Figures 16 and 17. This embodiment differs from the first embodiment in that the inner cylindrical portion 10 and the outer cylindrical portion 20 are replaced with a tubular portion 100, and the bypass groove 30 is replaced with a bypass path portion 110. Other than this, this embodiment is similar to the first embodiment. Therefore, in this embodiment, the differences from the first embodiment will be mainly described, and a description of the same portions as the first embodiment may be omitted.

[0114] 16, the sound insulating part 1 of this embodiment is configured by a single cylindrical tubular part 100 extending along a predetermined axial direction, and a detour path part 110 provided outside the tubular part 100. The sound insulating part 1 is capable of introducing sound waves to the inner peripheral side of the tubular part 100. In this embodiment, the direction in which the tubular part 100 extends is defined as the axial direction D1, as in the first embodiment, and the direction in which the tubular part 100 extends radially from the axis of the tubular part 100 is defined as the radial direction D3, as in the first embodiment.

[0115] The tubular portion 100 has, for example, a cylindrical shape and has an outer peripheral surface 101 on the outside in the radial direction D3 and an inner peripheral surface 102 on the inside in the radial direction D3. A bypass path portion 110 is connected to the outer peripheral surface 101. The inner peripheral surface 102 forms the transmission space S in this embodiment. The tubular portion 100 also has, at its end on the reverse transmission direction D1b side, an inlet 105 for introducing sound waves into the transmission space S, and at its end on the transmission direction D1a side, an outlet 106 for guiding the sound waves introduced into the transmission space S to the outside of the transmission space S. In this embodiment, the tubular portion 100 corresponds to the space forming portion, the inlet 105 corresponds to the introduction portion, and the outlet 106 corresponds to the outlet portion.

[0116] Furthermore, the cylindrical portion 100 has two communication holes 103, 104 that communicate with the bypass path portion 110. One of the two communication holes 103, 104 is formed closer to the reverse transmission direction D1b than the other. In other words, one of the two communication holes 103, 104 is formed closer to the introduction port 105 than the other.

[0117] Hereinafter, of the two communication holes 103, 104, the one closer to the inlet 105 will be referred to as the inlet-side communication hole 103, and the one farther from the inlet 105 will be referred to as the outlet-side communication hole 104. In this embodiment, the inlet-side communication hole 103 corresponds to an inlet portion that connects the transfer space S with the detour path portion 110 and guides sound waves from the transfer space S to the detour path portion 110. In addition, the outlet-side communication hole 104 in this embodiment corresponds to an outlet portion that connects the transfer space S with the detour path portion 110 and guides sound waves from the detour path portion 110 to the transfer space S. The inlet-side communication hole 103 and the outlet-side communication hole 104 are formed side by side along the axial direction D1 with a predetermined gap between them. Note that the tubular portion 100 may be formed, for example, in a rectangular cylindrical shape.

[0118] The detour path portion 110 has a hollow shape, allowing sound waves to propagate through the interior. Furthermore, the detour path portion 110 of this embodiment is expandable and contractible, and its length can be changed in response to expansion and contraction. Specifically, as shown in FIG. 17 , the detour path portion 110 has a bellows structure with repeated concave and convex portions on the outer periphery, and is expandable and contractible due to compressive and tensile forces. The detour path portion 110 is formed, for example, from an elastically deformable resin such as rubber. However, the material of the detour path portion 110 is not limited to this, and the detour path portion 110 may be formed from a material other than rubber.

[0119] Moreover, the detour path section 110 has one side connected to the inlet side communicating hole 103 and the other side connected to the outlet side communicating hole 104, and is in communication with the transmission space S. Therefore, the detour path section 110 forms a detour path that guides a portion of the sound waves introduced from the inlet 105 into the transmission space S to the outlet 106, bypassing a portion of the transmission space S. Specifically, the detour path section 110 guides a portion of the sound waves introduced into the transmission space S from the inlet side communicating hole 103, passes through the detour path section 110, and is guided to the transmission space S from the outlet side communicating hole 104, thereby bypassing a portion of the transmission space S. The sound waves introduced from the inlet side communicating hole 103 into the detour path section 110 pass through the detour path section 110, are guided to the outlet side communicating hole 104, and are returned to the transmission space S.

[0120] For this reason, the sound waves transmitted within the transmission space S are attenuated in intensity corresponding to the frequency band of the sound waves returned to the transmission space S via the detour path section 110. The detour path section 110 of this embodiment corresponds to a phase adjustment section that changes the phase of a portion of the sound waves introduced into the transmission space S.

[0121] The detour path section 110 is extendable and contractible, and its length can be changed accordingly. In this embodiment, the length of the detour path section 110 from the inlet-side communication hole 103 to the outlet-side communication hole 104 is referred to as the detour length. The more the detour path section 110 extends, the longer the detour length becomes, and conversely, the more the detour path section 110 contracts, the shorter the detour length becomes.

[0122] Therefore, by expanding or contracting the detour path portion 110, the frequency band of sound that can be attenuated by the detour path portion 110 can be changed. Specifically, by expanding the detour path portion 110 to increase the length of the detour path, it is possible to lower the frequency band of sound that corresponds to the detour path length among the frequency band of sound that can be attenuated by the sound insulating unit 1. On the other hand, by contracting the detour path portion 110 to shorten the length of the detour path, it is possible to raise the frequency band of sound that corresponds to the detour path length among the frequency band of sound that can be attenuated by the sound insulating unit 1. Therefore, it is possible to attenuate various frequency bands of sound that are guided from the transmission space S to the outside through the guide port 106.

[0123] (Sixth embodiment) Next, a sixth embodiment will be described with reference to FIG. 18. In this embodiment, the configuration of the detour path section 110 is different from that of the fifth embodiment. The rest is the same as in the fifth embodiment. Therefore, in this embodiment, the differences from the fifth embodiment will be mainly described, and a description of the same parts as in the fifth embodiment may be omitted.

[0124] 18, the sound insulating part 1 of this embodiment has two detour path portions 110. These two detour path portions 110 are connected to each other at different positions on the outer peripheral surface 101 of the tubular part 100 and are arranged apart from each other. Specifically, one of the two detour path portions 110 is formed at a position closer to the inlet 105 than the other detour path portion 110.

[0125] Hereinafter, of the two detour path sections 110, the one closer to the inlet 105 will be referred to as the first detour path section 120, and the one farther from the inlet 105 will be referred to as the second detour path section 130. The first detour path section 120 and the second detour path section 130 are formed side by side along the axial direction D1 with a predetermined gap between them. Although not shown, the first detour path section 120 and the second detour path section 130 are expandable and contractable with a bellows structure having repeatedly concave and convex outer peripheries, similar to the fifth embodiment, and the length can be changed according to the expansion and contraction.

[0126] The cylindrical portion 100 has a first inlet-side communication hole 103a and a first outlet-side communication hole 104a that communicate with the first detour path portion 120, and a second inlet-side communication hole 103b and a second outlet-side communication hole 104b that communicate with the second detour path portion 130. The first inlet-side communication hole 103a is formed closer to the reverse transmission direction D1b than the first outlet-side communication hole 104a, the second inlet-side communication hole 103b, and the second outlet-side communication hole 104b. In other words, the first inlet-side communication hole 103a is formed closer to the introduction port 105 than the first outlet-side communication hole 104a, the second inlet-side communication hole 103b, and the second outlet-side communication hole 104b. The first inlet-side communication hole 103a is an inlet for guiding sound waves to the first detour path portion 120. The first outlet-side communication hole 104a is an outlet portion for guiding the sound waves introduced into the first detour path portion 120 to the transmission space S.

[0127] The second inlet side communication hole 103b is formed closer to the reverse transmission direction D1b than the second outlet side communication hole 104b. That is, the second inlet side communication hole 103b is formed closer to the introduction port 105 than the second outlet side communication hole 104b. The second inlet side communication hole 103b is an inlet portion for guiding sound waves to the second detour path portion 130. The second outlet side communication hole 104b is an outlet portion for guiding sound waves introduced into the second detour path portion 130 to the transmission space S. In the tubular portion 100 of this embodiment, the number of inlet portions and the number of outlet portions are equal.

[0128] The first detour path section 120 of this embodiment formed in this manner is in communication with the transmission space S via the first inlet side communication hole 103a and the first outlet side communication hole 104a. Therefore, the first detour path section 120 forms a detour path that guides a portion of the sound waves introduced into the transmission space S to the outlet 106, bypassing a portion of the transmission space S. The sound waves introduced into the first detour path section 120 from the first inlet side communication hole 103a pass through the first detour path section 120 and are guided to the first outlet side communication hole 104a and returned to the transmission space S.

[0129] Furthermore, the second detour path section 130 of this embodiment is connected to the transmission space S via the second inlet side communication hole 103b and the second outlet side communication hole 104b. Therefore, the second detour path section 130 forms a detour path that guides a portion of the sound waves introduced into the transmission space S to the outlet 106, bypassing a portion of the transmission space S. The sound waves introduced into the second detour path section 130 from the second inlet side communication hole 103b pass through the second detour path section 130 and are guided to the second outlet side communication hole 104b, and are returned to the transmission space S.

[0130] Therefore, the sound waves transmitted within the transmission space S are attenuated in intensity corresponding to the frequency band of the sound waves returned to the transmission space S via the first detour path portion 120 and in intensity corresponding to the frequency band of the sound waves returned to the transmission space S via the second detour path portion 130. Furthermore, the first detour path portion 120 is extendable and contractible, so that the length from the first inlet side communication hole 103a to the first outlet side communication hole 104a can be changed. Furthermore, the second detour path portion 130 is extendable and contractible, so that the length from the second inlet side communication hole 103b to the second outlet side communication hole 104b can be changed.

[0131] Hereinafter, the length of the first detour path section 120 from the first inlet-side communication hole 103a to the first outlet-side communication hole 104a will be referred to as the "first detour path length." Furthermore, the length of the second detour path section 130 from the second inlet-side communication hole 103b to the second outlet-side communication hole 104b will be referred to as the "second detour path length." The first detour path section 120 and the second detour path section 130 are configured so that the first detour path length and the second detour path length can be different from each other. For example, the first detour path section 120 and the second detour path section 130 are configured so that the first detour path length when the first detour path length is the maximum is different from the second detour path length when the second detour path length is the maximum.

[0132] Therefore, by expanding or contracting the first detour path portion 120, it is possible to change the frequency band of sound that can be attenuated by the first detour path portion 120. Specifically, by expanding the first detour path portion 120 and lengthening the first detour path length, it is possible to lower the frequency band of sound that corresponds to the first detour path length, among the frequency band of sound that can be attenuated by the sound insulation unit 1. Furthermore, by expanding the second detour path portion 130 and lengthening the second detour path length, it is possible to lower the frequency band of sound that corresponds to the second detour path length, among the frequency band of sound that can be attenuated by the sound insulation unit 1.

[0133] In contrast to this, by shortening the first detour path section 120 and shortening the length of the first detour path, it is possible to raise the frequency band of sounds that corresponds to the first detour path length, among the frequency bands of sounds that can be attenuated by the sound insulating section 1. Furthermore, by shortening the second detour path section 130 and shortening the length of the second detour path, it is possible to raise the frequency band of sounds that corresponds to the second detour path length, among the frequency bands of sounds that can be attenuated by the sound insulating section 1.

[0134] According to this, the sound insulating part 1 can reduce the frequency band of sound corresponding to the first detour length and attenuate the frequency band of sound corresponding to the second detour length, thereby attenuating sounds of various frequency bands that are guided from the transmission space S to the outside through the guide outlet 106.

[0135] Seventh embodiment Next, a seventh embodiment will be described with reference to FIG. 19. In this embodiment, the configuration of the second detour path section 130 differs from that of the sixth embodiment. Other than this, the seventh embodiment is similar to the sixth embodiment. Therefore, in this embodiment, the differences from the sixth embodiment will be mainly described, and a description of the similarities between the sixth embodiment and the sixth embodiment may be omitted.

[0136] 19, the second detour path section 130 of this embodiment is connected to the first detour path section 120. That is, of the first detour path section 120 and the second detour path section 130, the second detour path section 130 that is farther from the inlet 105 is connected to the first detour path section 120 that is closer to the inlet 105. Furthermore, the end of the second detour path section 130 that is closer to the inlet 105 is connected to a portion of the detour path formed by the first detour path section 120 that is closer to the outlet 106. Therefore, unlike the sixth embodiment, the tubular section 100 of this embodiment does not have a second inlet side communication hole 103b for guiding sound waves to the second detour path section 130. That is, the tubular section 100 of this embodiment has three holes: a first inlet side communication hole 103a, a first outlet side communication hole 104a, and a second outlet side communication hole 104b. Therefore, the number of inlet portions and the number of outlet portions are different in the cylindrical portion 100 of this embodiment. Specifically, the number of inlet portions is less than the number of outlet portions.

[0137] The first detour path portion 120 of this embodiment formed in this manner is in communication with the transmission space S via the first inlet side communication hole 103a and the first outlet side communication hole 104a. Therefore, the first detour path portion 120 makes it possible for a portion of the sound waves introduced into the transmission space S to bypass a portion of the transmission space S and be guided to the outside of the sound-insulating part 1.

[0138] Furthermore, the second detour path section 130 of this embodiment is in communication with the transmission space S via the first detour path section 120 and the second outlet-side communicating hole 104b. Therefore, the second detour path section 130 allows a portion of the sound waves introduced into the transmission space S to bypass a portion of the transmission space S and be guided to the outside of the sound insulating section 1. The first detour path section 120 and the second detour path section 130 have changeable detour path lengths. Hereinafter, in this embodiment, the length from the first inlet-side communicating hole 103a to the portion where the second detour path section 130 is connected plus the length from the portion where the first detour path section 120 is connected to the second outlet-side communicating hole 104b will be referred to as the second detour path length. In addition, the first detour path section 120 and the second detour path section 130 of this embodiment are configured so that the length of the first detour path section 120 and the length of the second detour path section 130 can be different from each other, as in the sixth embodiment.

[0139] The sound waves introduced from the first inlet side communication hole 103a into the first detour path section 120 pass through the first detour path section 120 and are guided to the first outlet side communication hole 104a, and are returned to the transmission space S. Furthermore, the sound waves introduced from the first detour path section 120 into the second detour path section 130 pass through the second detour path section 130 and are guided to the second outlet side communication hole 104b, and are returned to the transmission space S. For this reason, the sound waves transmitted within the transmission space S have their intensity attenuated, corresponding to the frequency band of the sound waves returned to the transmission space S via the first detour path section 120. Furthermore, the sound waves transmitted within the transmission space S have their intensity attenuated, corresponding to the frequency band of the sound waves returned to the transmission space S via the first detour path section 120 and the second detour path section 130.

[0140] Therefore, by expanding or contracting the first detour path portion 120, the frequency band of sound that can be attenuated by the first detour path portion 120 and the second detour path portion 130 can be changed. Specifically, by expanding the first detour path portion 120 and lengthening the first detour path length, it is possible to lower the frequency band of sound that corresponds to the first detour path length among the frequency band of sound that can be attenuated by the sound insulating unit 1. Furthermore, by lengthening the first detour path length, it is possible to lower the frequency band of sound that corresponds to the second detour path length among the frequency band of sound that can be attenuated by the sound insulating unit 1. Furthermore, by expanding the second detour path portion 130 and lengthening the second detour path length, it is possible to lower the frequency band of sound that corresponds to the second detour path length among the frequency band of sound that can be attenuated by the sound insulating unit 1.

[0141] In contrast to this, by shortening the first detour path section 120 and shortening the length of the first detour path, it is possible to raise the frequency band of sounds that corresponds to the first detour path length among the frequency band of sounds that can be attenuated by the sound insulating unit 1. Furthermore, by lengthening the length of the first detour path, it is possible to raise the frequency band of sounds that corresponds to the second detour path length among the frequency band of sounds that can be attenuated by the sound insulating unit 1. Furthermore, by shortening the second detour path section 130 and shortening the length of the second detour path, it is possible to raise the frequency band of sounds that corresponds to the second detour path length among the frequency band of sounds that can be attenuated by the sound insulating unit 1.

[0142] Therefore, it is possible to attenuate sounds of various frequency bands that are guided from the transmission space S to the outside through the guide outlet 106. Furthermore, by connecting the second detour path portion 130 to the first detour path portion 120, it is possible to achieve a configuration that does not have the second inlet side communication hole 103b, as compared to the sixth embodiment. Therefore, it is possible to easily reduce the size of the tubular portion 100 in the axial direction D1.

[0143] (First modified example of the seventh embodiment) In the seventh embodiment described above, an example was described in which the second detour path section 130 is connected to the first detour path section 120, the first inlet-side communication hole 103a, the first outlet-side communication hole 104a, and the second outlet-side communication hole 104b are formed in the tubular section 100, and the second inlet-side communication hole 103b is not formed. However, this is not limiting. For example, the first detour path section 120 may be connected to the second detour path section 130. In this case, as shown in FIG. 20 , the end of the first detour path section 120 farther from the inlet 105 may be connected to a portion of the detour path formed by the second detour path section 130 that is closer to the inlet 105. The tubular section 100 may be configured to have three holes: the first inlet-side communication hole 103a, the second inlet-side communication hole 103b, and the second outlet-side communication hole 104b. In this case, the number of inlet portions and the number of outlet portions of the tubular portion 100 will be different, and specifically, the number of inlet portions will be greater than the number of outlet portions.

[0144] (Second modified example of the seventh embodiment) In the seventh embodiment described above, an example has been described in which the first detour path section 120 and the second detour path section 130 are configured to have different lengths, but the present invention is not limited to this. For example, the first detour path section 120 and the second detour path section 130 may be configured to have the same length.

[0145] (Eighth embodiment) Next, an eighth embodiment will be described with reference to FIGS. 21 and 22. In this embodiment, the configuration of the bypass path section 110 is different from that of the seventh embodiment. However, the configuration of the bypass path section 110 of this embodiment is similar to the structure of the bypass pipe 80 described in the fourth embodiment. Other than this, this embodiment is similar to the fourth and seventh embodiments. Therefore, in this embodiment, the parts that are different from the fourth and seventh embodiments will be mainly described, and a description of the parts that are similar to the fourth and seventh embodiments may be omitted.

[0146] Similar to the fourth embodiment, the sound-insulating part 1 of this embodiment is configured by fitting a second cylindrical part 70 inside a first cylindrical part 60. The sound-insulating part 1 has a part of a bypass pipe 80 provided inside each of the first cylindrical part 60 and the second cylindrical part 70. As shown in FIG. 21 , the part of the bypass pipe 80 provided inside the first cylindrical part 60 of this embodiment is referred to as a first helical pipe 83, and the part provided inside the second cylindrical part 70 is referred to as a second helical pipe 84.

[0147] As in the fourth embodiment, the first helical tube 83 and the second helical tube 84 are arranged around the axis CL of the sound insulating unit 1 and are formed in a spiral shape extending in the axial direction D1. The first helical tube 83 is inserted into the second helical tube 84 to form the detour tube 80. In this embodiment, the second helical tube 84 is inserted into and connected to a midpoint of the first helical tube 83. In addition, the first helical tube 83 rotates integrally with the first cylindrical portion 60 in the circumferential direction D2, so that the portion of the first helical tube 83 inserted into the second helical tube 84 can be increased or decreased.

[0148] Furthermore, the first cylindrical portion 60 of this embodiment has a common inlet opening 63 and a first outlet opening 64 formed on the first inner circumferential surface 61. The common inlet opening 63 corresponds to the first inlet side communicating hole 103a in the seventh embodiment, and guides the sound waves introduced into the transmission space S to the first helical tube 83 and the second helical tube 84. The first outlet opening 64 corresponds to the first outlet side communicating hole 104a in the seventh embodiment, and guides the sound waves introduced into the first helical tube 83 to the transmission space S.

[0149] Furthermore, the second cylindrical portion 70 of this embodiment has a second outlet opening 73 formed on the second inner circumferential surface 71. The second outlet opening 73 corresponds to the second outlet-side communicating hole 104b in the seventh embodiment, and guides sound waves introduced into the second helical tube 84 via the first helical tube 83 to the transmission space S. The common inlet opening 63 is an inlet portion for guiding sound waves to the first helical tube 83 and the second helical tube 84. The first outlet opening 64 is an outlet portion for guiding sound waves introduced into the first helical tube 83 to the transmission space S. The second outlet opening 73 is an outlet portion for guiding sound waves introduced into the second helical tube 84 to the transmission space S.

[0150] For this reason, in this embodiment, sound waves introduced into the first helical tube 83 from the common inlet opening 63 pass through the first helical tube 83 and are guided to the first outlet opening 64 and returned to the transmission space S. Also, sound waves introduced from the first helical tube 83 to the second helical tube 84 pass through the second helical tube 84 and are guided to the second outlet opening 73 and returned to the transmission space S. Hereinafter, in this embodiment, the length of the first helical tube 83 from the common inlet opening 63 to the first outlet opening 64 will be referred to as the first detour length. Also, the length from the common inlet opening 63 to the location where the second helical tube 84 is connected plus the length from the location where the second helical tube 84 is connected to the second outlet opening 73 will be referred to as the second detour length.

[0151] As shown in Fig. 22, the sound waves transmitted within the transmission space S are attenuated in intensity at a frequency band corresponding to the sound waves returned to the transmission space S via the first helical tube 83. Furthermore, the sound waves transmitted within the transmission space S are attenuated in intensity at a frequency band corresponding to the sound waves returned to the transmission space S via the first helical tube 83 and the second helical tube 84. In Fig. 22, among the attenuated sound waves, the higher frequency side indicates the intensity of the sound waves attenuated by the sound waves being transmitted through the first helical tube 83, and the lower frequency side indicates the intensity of the sound waves attenuated by the sound waves being transmitted through the second helical tube 84. The reason that the frequency of the sound waves attenuated by the transmission through the first helical tube 83 is high is because the second detour length is longer than the first detour length.

[0152] In addition, the bypass pipe 80 is configured so that the portion of the first spiral pipe 83 inserted inside the second spiral pipe 84 can be increased or decreased by rotating the first spiral pipe 83 integrally with the first cylindrical portion 60 in the circumferential direction D2.

[0153] Therefore, by rotating the first cylindrical portion 60 in the circumferential direction D2, it is possible to change the frequency band of sound that can be attenuated by the bypass pipe 80. Specifically, by rotating the first cylindrical portion 60 to increase the length of the first bypass path, it is possible to lower the frequency band of sound that corresponds to the first bypass path length, among the frequency band of sound that can be attenuated by the sound insulation unit 1. Furthermore, by increasing the length of the first bypass path, it is possible to lower the frequency band of sound that corresponds to the second bypass path length, among the frequency band of sound that can be attenuated by the sound insulation unit 1.

[0154] In contrast to this, by rotating the first cylindrical portion 60 to shorten the length of the first detour route, it is possible to raise the frequency band of sounds that corresponds to the first detour route length among the frequency bands of sounds that can be attenuated by the sound insulating unit 1. Furthermore, by lengthening the length of the first detour route, it is possible to raise the frequency band of sounds that corresponds to the second detour route length among the frequency bands of sounds that can be attenuated by the sound insulating unit 1.

[0155] According to this, the sound insulating part 1 can reduce the frequency band of sound corresponding to the first detour length and attenuate the frequency band of sound corresponding to the second detour length, thereby attenuating sounds of various frequency bands that are guided out from the transfer space S to the outside.

[0156] (Ninth embodiment) Next, a ninth embodiment will be described with reference to Figures 23 and 24. In this embodiment, the configuration of the detour path section 110 is different from that of the fifth embodiment. Other than this, the configuration is the same as that of the fifth embodiment. Therefore, in this embodiment, the differences from the fifth embodiment will be mainly described, and a description of the same parts as the fifth embodiment may be omitted.

[0157] 23, the detour path section 110 of this embodiment is composed of two detour connection sections 115 connected to the tubular section 100, and a detour path forming section 116 that communicates with these two detour connection sections 115. The detour path section 110, which is composed of the detour connection sections 115 and the detour path forming section 116, forms a detour path that causes a portion of the sound waves introduced from the inlet 105 into the transmission space S to bypass the transmission space S and return to the transmission space S. The detour connection section 115 and the detour path forming section 116 are hollow, allowing sound waves to propagate through the interior thereof.

[0158] One of the two bypass connecting portions 115 is provided in a portion of the tubular portion 100 where the inlet side communicating hole 103 is formed, and communicates with the transmission space S. The other of the two bypass connecting portions 115 is provided in a portion of the tubular portion 100 where the outlet side communicating hole 104 is formed, and communicates with the transmission space S. The two bypass connecting portions 115 are formed in a tubular shape that protrudes outward in the radial direction D3 from the portion connected to the tubular portion 100. A detour path forming portion 116 is inserted inside the two bypass connecting portions 115. Hereinafter, of the two bypass connecting portions 115, the one that communicates with the inlet side communicating hole 103 will be referred to as the inlet side connecting portion 115a, and the other that communicates with the outlet side communicating hole 104 will be referred to as the outlet side connecting portion 115b.

[0159] The detour path forming portion 116 is formed in a U-shaped tube, with one end inserted into the inlet side connection portion 115a and the other end inserted into the outlet side connection portion 115b. The detour path forming portion 116 communicates with the transmission space S via the inlet side connection portion 115a and the outlet side connection portion 115b. The detour path forming portion 116 has an inlet side insertion portion 116a inserted into the inlet side connection portion 115a, an outlet side insertion portion 116b inserted into the outlet side connection portion 115b, and an insertion connection portion 116c connecting the inlet side insertion portion 116a and the outlet side insertion portion 116b.

[0160] The inlet-side insertion portion 116a has an outer diameter smaller than the inner diameter of the inlet-side connection portion 115a, allowing it to be inserted into the inlet-side connection portion 115a. The inlet-side connection portion 115a is formed in a cylindrical shape extending along the radial direction D3, allowing it to transmit sound waves transmitted from the inlet-side connection portion 115a. The insertion connection portion 116c is formed in a cylindrical shape extending along the axial direction D1, with one end connected to the inlet-side insertion portion 116a and the other end connected to the outlet-side insertion portion 116b. The insertion connection portion 116c is capable of transmitting sound waves transmitted from the inlet-side insertion portion 116a to the outlet-side insertion portion 116b. The outlet-side insertion portion 116b has an outer diameter smaller than the inner diameter of the outlet-side connection portion 115b, allowing it to be inserted into the outlet-side connection portion 115b. The outlet-side connecting portion 115b is formed in a cylindrical shape extending along the radial direction D3, and is capable of transmitting sound waves transmitted from the insertion connecting portion 116c to the outlet-side connecting portion 115b.

[0161] Therefore, the detour path section 110, which is constituted by the detour connection section 115 and the detour path forming section 116, makes it possible for a portion of the sound waves introduced into the transmission space S to bypass a portion of the transmission space S and be guided to the outside of the sound-insulating section 1. Then, the sound waves introduced into the detour path section 110 from the inlet-side communication hole 103 pass through the detour path section 110 and are guided to the outlet-side communication hole 104 and returned to the transmission space S. Therefore, the sound waves transmitted within the transmission space S have their intensity attenuated, corresponding to the frequency band of the sound waves returned to the transmission space S via the detour path section 110.

[0162] Furthermore, the detour path forming portion 116 of this embodiment is movable along the direction in which the inlet-side connecting portion 115a and the outlet-side connecting portion 115b extend. Specifically, as shown in Figures 23 and 24, the detour path forming portion 116 moves in the radial direction D3, thereby increasing or decreasing the portion of the inlet-side insertion portion 116a inserted into the inlet-side connecting portion 115a and increasing or decreasing the portion of the outlet-side insertion portion 116b inserted into the outlet-side connecting portion 115b. In other words, the detour path forming portion 116 moves in the radial direction D3, thereby increasing or decreasing the amount by which the inlet-side insertion portion 116a is inserted into the inlet-side connecting portion 115a and the amount by which the outlet-side insertion portion 116b is inserted into the outlet-side connecting portion 115b.

[0163] The length of the detour path in this embodiment from the inlet-side communicating hole 103 to the outlet-side communicating hole 104 can be changed by increasing or decreasing the portion of the inlet-side insertion section 116a that is inserted into the inlet-side connecting section 115a and the portion of the outlet-side insertion section 116b that is inserted into the outlet-side connecting section 115b. In other words, the length of the detour path in the detour path section 110 can be changed by changing the distance from the inlet-side communicating hole 103 to the inlet-side insertion section 116a and the distance from the outlet-side communicating hole 104 to the outlet-side insertion section 116b.

[0164] In this embodiment, as shown in Fig. 23, the detour path forming portion 116 moves outward in the radial direction D3, and the portion of the inlet-side insertion portion 116a that is inserted into the inlet-side connecting portion 115a and the portion of the outlet-side insertion portion 116b that is inserted into the outlet-side connecting portion 115b increase, and the detour path length becomes shorter. In contrast, as shown in Fig. 24, the detour path forming portion 116 moves inward in the radial direction D3, and the portion of the inlet-side insertion portion 116a that is inserted into the inlet-side connecting portion 115a and the portion of the outlet-side insertion portion 116b that is inserted into the outlet-side connecting portion 115b decrease, and the detour path length becomes longer.

[0165] Therefore, by moving the detour path forming portion 116 in the radial direction D3, it is possible to change the frequency band of sound that can be attenuated by the detour path portion 110. Specifically, by moving the detour path forming portion 116 to shorten the detour path length, it is possible to increase the frequency band of sound that corresponds to the detour path length, among the frequency band of sound that can be attenuated by the sound insulation portion 1. On the other hand, by moving the detour path forming portion 116 to increase the detour path length, it is possible to lower the frequency band of sound that corresponds to the detour path length, among the frequency band of sound that can be attenuated by the sound insulation portion 1.

[0166] This allows the frequency band of sound waves that can be attenuated by the bypass path section 110 to be changed, so that sound waves of various frequency bands that are guided out from the transmission space S to the outside through the guide outlet 106 can be attenuated.

[0167] (Other embodiments) Representative embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments and can be modified in various ways, for example, as follows.

[0168] In the above embodiment, an example has been described in which the sound-insulating unit 1 is applied to a vehicle and attached to a vehicle component that generates noise, such as an electric compressor, but the sound-insulating unit 1 is not limited to this. The sound-insulating unit 1 can be applied to various devices other than vehicles.

[0169] In the above-described fourth embodiment, an example has been described in which the bypass pipe 80 is configured by the first spiral bypass pipe 81 provided inside the first cylindrical portion 60 and the second spiral bypass pipe 82 provided inside the second cylindrical portion 70, but the configuration is not limited to this. For example, the bypass pipe 80 may be configured such that two linear tubular members are provided inside the first cylindrical portion 60 and the second cylindrical portion 70. In this case, one of the two tubular members may be inserted inside the other, and the inserted amount may be changed by moving the first cylindrical portion 60 and the second cylindrical portion 70 in the axial direction D1.

[0170] In the above-described fourth to seventh and ninth embodiments, examples have been described in which the tubular portion 100 extends along a predetermined axial direction and the detour path portion 110 is provided outside the tubular portion 100, but the present invention is not limited to this. For example, the tubular portion 100 may be formed so that a portion thereof is bent rather than extending along the axial direction.

[0171] In the above-described fourth embodiment, an example was described in which the opening surfaces of the inlet opening 62, which guides sound waves from the transmission space S to the bypass path, and the outlet opening 72, which guides sound waves from the bypass path to the transmission space S, intersect with the radial direction D3. In the first to third, fifth to seventh, and ninth embodiments, the opening surfaces of the inlet-side through hole 141, the inlet-side communication hole 103, and the common inlet opening 63, which correspond to the inlet opening 62, may also intersect with the radial direction D3. Furthermore, in the first to third, fifth to seventh, and ninth embodiments, the opening surfaces of the outlet-side through hole 142, the outlet-side communication hole 104, the first outlet opening 64, and the second outlet opening 73, which correspond to the outlet opening 72, may also intersect with the radial direction D3.

[0172] In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle.

[0173] In the above-described embodiments, when numerical values ​​such as the number, values, amounts, ranges, etc. of components of the embodiments are mentioned, they are not limited to the specific numbers unless they are specifically stated as essential or are clearly limited to a specific number in principle.

[0174] In the above-described embodiments, when referring to the shapes, positional relationships, etc. of components, etc., the shapes, positional relationships, etc. are not limited to those unless otherwise specified or when they are fundamentally limited to specific shapes, positional relationships, etc.

[0175] (Aspects of the present disclosure) The present disclosure described above can be understood from the following viewpoints, for example. [First viewpoint] A sound-insulating part, a space forming section (10, 20, 60, 70, 100) that forms a transmission space (S) for transmitting sound waves and has an introduction section (12, 105) that introduces the sound waves into the transmission space and an extraction section (13, 106) that extracts the sound waves introduced into the transmission space to the outside of the transmission space; a phase adjusting unit (30, 80, 110) that attenuates the sound waves corresponding to the frequency of the sound waves whose phases have been changed among the sound waves that are transmitted through the transmission space by changing the phase of the sound waves that are transmitted through the transmission space; The phase adjustment unit is a sound-insulating unit that changes the frequency band of the sound waves whose phase is changed. [Second viewpoint] a bypass path (30, 80, 110) for guiding a part of the sound waves introduced from the introduction part into the transmission space to the outlet part by bypassing a part of the transmission space, the space forming portion has an inlet portion (62, 63, 103, 141) that connects the transmission space with the detour path and guides the sound waves from the transmission space to the detour path, and an outlet portion (64, 72, 73, 104, 142) that connects the transmission space with the detour path and guides the sound waves from the detour path to the transmission space, When the length of the detour route from the entrance portion to the exit portion is defined as a detour route length, the detour route length is changeable, The sound insulating section according to a first aspect, wherein the phase adjustment section is constituted by the bypass path. [Third Perspective] The sound-proofing section according to a second aspect, wherein the detour path changes the phase of the sound waves that have passed through the detour path and are transmitted to the outlet portion so that the phase of the sound waves that have passed through the detour path approaches the opposite phase of the phase of the sound waves that have been transmitted to the outlet portion without passing through the detour path. [Fourth viewpoint] The sound-proofing section according to a third aspect, wherein the detour path changes the phase of the sound wave that has passed through the detour path so as to satisfy the following mathematical formula using an arbitrary coefficient N that is an integer, where Δφ is the amount of phase shift between the sound wave that has passed through the detour path and been transmitted to the exit portion and the sound wave that has been transmitted to the exit portion without passing through the detour path. (Number 1) +150+(N×360)≦Δφ≦+210+(N×360) [Fifth viewpoint] The sound-proof section according to a fourth aspect, wherein the detour path changes the phase of the sound wave that has passed through the detour path so as to satisfy the following formula using an arbitrary coefficient N that is an integer: (Number 2) Δφ=±180+(N×360) [Sixth viewpoint] The sound-proofing section according to any one of the second to fifth aspects, wherein the opening surfaces of the inlet section and the outlet section intersect with the radial direction when the direction in which they expand radially from the axis of the transmission space is taken as the radial direction. [Seventh viewpoint] The sound-proofing section according to any one of the second to sixth aspects, wherein the detour path is formed inside the space-forming section. [Eighth viewpoint] the space forming portion includes an inner cylindrical portion (10) that extends along an axial direction, which is a direction in which a predetermined axis extends, and is formed in a hollow cylindrical shape to form the transmission space, and an outer cylindrical portion (20) that extends along the axial direction, is disposed outside the inner cylindrical portion, and surrounds the outer periphery of the inner cylindrical portion, the inner cylindrical portion has an inner outer peripheral surface (111) facing the outer cylindrical portion, an inner inner peripheral surface (112) surrounding the transmission space, and a plurality of through holes (141, 142) formed to penetrate from the inner outer peripheral surface to the inner inner peripheral surface and provided at predetermined intervals in the axial direction, The outer cylindrical portion has an outer inner peripheral surface (212) facing the inner outer peripheral surface, the bypass path is configured by a bypass groove (30) formed in a groove shape at a position on the outer inner circumferential surface facing the plurality of through holes, The inlet portion and the outlet portion are any of the plurality of through holes, At least one of the inner cylindrical portion and the outer cylindrical portion is rotatable in a circumferential direction around the axis, The sound-insulating portion according to a seventh aspect, wherein the detour groove has a length that changes depending on a change in the relative position between the inner cylindrical portion and the outer cylindrical portion in the circumferential direction. [Ninth viewpoint] The sound-proofing section according to an eighth aspect, wherein the detour groove has a one-side groove portion (31, 32, 331) that transmits the sound waves transmitted from the inlet portion to the detour groove to one side in the circumferential direction and leads them to the outlet portion, and a other-side groove portion (31, 32, 332) that transmits the sound waves transmitted from the inlet portion to the detour groove to the other side in the circumferential direction and leads them to the outlet portion. [10th viewpoint] the inner cylindrical portion has a plurality of divided inner cylindrical portions (40, 50) arranged in the axial direction, each divided inner cylindrical portion having at least one through hole formed therein; The sound-proofing part according to an eighth aspect, wherein the plurality of divided inner cylindrical parts are rotatable in the circumferential direction independently of one another. [11th viewpoint] the space forming portion has a first forming portion (60) and a second forming portion (70) that extend along an axial direction, which is a direction in which a predetermined axis extends, and form the transmission space; the bypass path includes a hollow first bypass pipe (81) provided in the first forming portion and a hollow second bypass pipe (82) provided in the second forming portion, the first bypass pipe has one side communicating with the inlet portion and the other side communicating with the second bypass pipe; the second bypass pipe has one side communicating with the outlet portion and the other side communicating with the first bypass pipe, At least one of the first forming portion and the second forming portion is movable in the axial direction, The sound-insulating section described in the seventh aspect, wherein the first bypass pipe and the second bypass pipe can be inserted into each other, and the bypass length changes as the insertion amount of the first bypass pipe and the second bypass pipe changes depending on the change in the relative position of the first forming section and the second forming section in the axial direction. [12th viewpoint] The sound-insulating section according to any one of the second to sixth aspects, wherein the detour path is formed outside the space-forming section. [13th viewpoint] A plurality of the detour paths are provided, the space forming portion has a plurality of the inlet portions and the outlet portions that communicate with the plurality of the bypass paths, respectively; The sound-insulating section according to a twelfth aspect, wherein the plurality of detour paths have different detour path lengths. [14th viewpoint] A plurality of the detour paths are provided, the space forming portion has at least one inlet portion communicating with any one of the plurality of detour paths, and at least one outlet portion communicating with any one of the plurality of detour paths, At least one of the plurality of bypass paths communicates with one another, The sound-insulating section according to a twelfth aspect, wherein the inlet portions and the outlet portions are different in number from each other. [15th viewpoint] The sound-insulating section according to a fourteenth aspect, wherein the plurality of detour paths have different detour path lengths. [Explanation of symbols]

[0176] 10, 20, 60, 70, 100 Space forming part 12, 105 Introduction 13, 106 Derivation part 30, 80, 100 Phase adjustment section S Transmission Space

Claims

1. A sound-insulating part, a space forming section (10, 20, 60, 70, 100) that forms a transmission space (S) for transmitting sound waves and has an introduction section (12, 105) that introduces the sound waves into the transmission space and an extraction section (13, 106) that extracts the sound waves introduced into the transmission space to the outside of the transmission space; a phase adjusting unit (30, 80, 110) that attenuates the sound waves corresponding to the frequency of the sound waves whose phases have been changed among the sound waves that are transmitted through the transmission space by changing the phase of some of the sound waves that are transmitted through the transmission space; The phase adjustment unit is a sound-insulating unit that changes the frequency band of the sound waves whose phase is changed.

2. a bypass path (30, 80, 110) for guiding a part of the sound waves introduced from the introduction part into the transmission space to the extraction part by bypassing a part of the transmission space, The space forming portion has an inlet portion (62, 63, 103, 141) that connects the transmission space with the detour path and guides the sound waves from the transmission space to the detour path, and an outlet portion (64, 72, 73, 104, 142) that connects the transmission space with the detour path and guides the sound waves from the detour path to the transmission space, When the length of the detour route from the entrance portion to the exit portion is defined as a detour route length, the detour route length is changeable, The sound insulating section according to claim 1 , wherein the phase adjusting section is configured by the bypass path.

3. 3. The sound-insulating section of claim 2, wherein the detour path changes the phase of the sound waves that have passed through the detour path and are transmitted to the outlet portion so that the phase of the sound waves that have passed through the detour path approaches the opposite phase of the phase of the sound waves that have been transmitted to the outlet portion without passing through the detour path.

4. The sound-insulating section according to claim 3, wherein the detour path changes the phase of the sound wave that has passed through the detour path so as to satisfy the following formula using an arbitrary coefficient N, which is an integer, when the amount of phase shift between the sound wave that has passed through the detour path and been transmitted to the exit portion and the sound wave that has passed through the detour path and been transmitted to the exit portion without passing through the detour path is Δφ: (Equation 1) +150+(N×360)≦Δφ≦+210+(N×360)

5. The sound-insulating section according to claim 4 , wherein the detour path changes the phase of the sound wave that has passed through the detour path so as to satisfy the following mathematical expression using an arbitrary coefficient N that is an integer: (Equation 2) Δφ=±180+(N×360)

6. The sound-proofing section according to any one of claims 2 to 5, wherein the opening surfaces of the inlet section and the outlet section intersect with the radial direction when the direction in which they expand radially from the axis of the transmission space is taken as the radial direction.

7. The sound insulating section according to claim 2 , wherein the detour path is formed inside the space forming section.

8. The space forming portion includes an inner cylindrical portion (10) that extends along an axial direction, which is a direction in which a predetermined axis extends, and is formed in a hollow cylindrical shape to form the transmission space, and an outer cylindrical portion (20) that extends along the axial direction, is disposed outside the inner cylindrical portion, and surrounds the outer periphery of the inner cylindrical portion, The inner cylindrical portion has an inner outer peripheral surface (111) facing the outer cylindrical portion, an inner inner peripheral surface (112) surrounding the transmission space, and a plurality of through holes (141, 142) formed to penetrate from the inner outer peripheral surface to the inner inner peripheral surface and provided at predetermined intervals in the axial direction, The outer cylindrical portion has an outer inner peripheral surface (212) facing the inner outer peripheral surface, The detour path is configured by detour grooves (30) formed in a groove shape at positions on the outer inner circumferential surface facing the plurality of through holes, The inlet portion and the outlet portion are any of the plurality of through holes, At least one of the inner cylindrical portion and the outer cylindrical portion is rotatable in a circumferential direction around the axis, The sound-insulating portion according to claim 7 , wherein the length of the detour groove changes depending on a change in the relative position between the inner cylindrical portion and the outer cylindrical portion in the circumferential direction.

9. The sound-insulating portion of claim 8, wherein the bypass groove has a one-side groove portion (31, 32, 331) that transmits the sound waves transmitted from the inlet portion to the bypass groove to one side in the circumferential direction and guides them to the outlet portion, and a other-side groove portion (31, 32, 332) that transmits the sound waves transmitted from the inlet portion to the bypass groove to the other side in the circumferential direction and guides them to the outlet portion.

10. the inner cylindrical portion has a plurality of divided inner cylindrical portions (40, 50) arranged in the axial direction, each divided inner cylindrical portion having at least one through hole formed therein; The sound-insulating section according to claim 8 , wherein each of the plurality of divided inner cylindrical sections is rotatable in the circumferential direction independently of one another.

11. The space forming portion has a first forming portion (60) and a second forming portion (70) that extend along an axial direction, which is a direction in which a predetermined axis extends, to form the transmission space, The bypass path includes a hollow first bypass pipe (81) provided in the first forming portion and a hollow second bypass pipe (82) provided in the second forming portion, the first bypass pipe has one side communicating with the inlet portion and the other side communicating with the second bypass pipe; the second bypass pipe has one side communicating with the outlet portion and the other side communicating with the first bypass pipe, At least one of the first forming portion and the second forming portion is movable in the axial direction, The sound-insulating section of claim 7, wherein the first bypass pipe and the second bypass pipe can be inserted into each other, and the bypass length changes as the insertion amount of the first bypass pipe and the second bypass pipe changes depending on the change in the relative position of the first forming section and the second forming section in the axial direction.

12. 6. The sound insulating section according to claim 2, wherein the detour path is formed outside the space forming section.

13. A plurality of the detour paths are provided, the space forming portion has a plurality of the inlet portions and the outlet portions that communicate with the plurality of the bypass paths, respectively; The sound insulating section according to claim 12 , wherein the plurality of detour paths have different detour path lengths.

14. A plurality of the detour paths are provided, the space forming portion has at least one inlet portion communicating with any one of the plurality of detour paths, and at least one outlet portion communicating with any one of the plurality of detour paths, At least one of the plurality of bypass paths communicates with one another, The sound insulating section according to claim 12 , wherein the inlet sections and the outlet sections are of different numbers.

15. The sound insulating section according to claim 14 , wherein the plurality of detour paths have different detour lengths.

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