Vehicle sound output device and vehicle sound propagation device

Abstract

To enable the sound emanated by sound output parts disposed inside a vehicle to properly propagate from the inside of the vehicle to the outside of the vehicle, not through a panel opening.SOLUTION: A sound output device 1 for a vehicle has a sound output part 10 for emanating sound of a predetermined frequency, a double wall 20 disposed at the outer side of the vehicle relative to the sound output part 10 and formed of an inner wall part 21 and an outer wall part 22 apart from each other in the inner and outer direction relative to the vehicle, and an intermediate layer 30 which is formed in a closed space between the inner wall part 21 and the outer wall part 22 and allows sound to transmit through it.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vehicle sound output device and a vehicle sound propagation device that are mounted on a vehicle. [Background technology]

[0002] Conventionally, a vehicle sound output device mounted on a vehicle or the like is known (for example, Patent Document 1). The vehicle sound output device described in Patent Document 1 is a device that includes a sound generating unit such as a horn or a speaker, and makes people around the vehicle hear the sound generated by the sound generating unit. The sound generating unit is disposed on the inside of the vehicle (i.e., the rear side of the vehicle) relative to the radiator grille and front bumper, which are exterior panels of the vehicle.

[0003] In the above-mentioned sound output device, the sound generated by the sound generating unit is emitted to the outside of the vehicle through an opening provided in the exterior panel or cover part. In particular, if the sound generating unit is disposed on the inside of the vehicle near an opening in the exterior panel or the like, the sound generated by the sound generating unit is easily emitted to the outside of the vehicle through the opening, so that the sound is easily propagated over a wide area even with a small output. In this regard, if an opening is provided in the exterior panel or the like as described above, it is easier for people outside the vehicle to hear the sound generated by the sound generating unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-330852 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in recent years, with the progress of electric vehicles and the demand for improved fuel efficiency, there is a trend toward reducing the size of openings in exterior panels, etc. In such a structure in which the openings in the exterior panels, etc. are reduced or eliminated, the sound emitted by the sound generating unit is more likely to be reflected by the rear surface of the exterior panel, etc., compared to a structure with a large opening, and the sound transmitted through the opening from the inside to the outside of the vehicle is reduced, so there is a risk that it will be difficult for people outside the vehicle to hear the sound emitted by the sound generating unit.

[0006] The present invention has been made in consideration of these points, and aims to provide a vehicle sound output device and a vehicle sound propagation device that are capable of properly propagating sound emitted by a sound-generating unit located on the inside of the vehicle from the inside of the vehicle to the outside of the vehicle without passing through a panel opening. [Means for solving the problem]

[0007] One aspect of the present invention is a sound output device for a vehicle comprising: a sound producing unit that emits sound of a predetermined frequency; a double wall consisting of an inner wall portion and an outer wall portion that are positioned outside the vehicle from the sound producing unit and spaced apart in the vehicle's interior / exterior direction; and an intermediate layer that is formed in an enclosed space between the inner wall portion and the outer wall portion and through which the sound passes.

[0008] According to this configuration, sound of a predetermined frequency emitted by the sound generating unit can be transmitted by resonance from the inner wall portion of the double wall through the intermediate layer to the outer wall portion, and can then be propagated to the outside of the vehicle from the outer wall portion. Therefore, the sound generated by the sound generating unit can be appropriately propagated from the inside of the vehicle to the outside of the vehicle without passing through the panel opening provided in the wall.

[0009] One aspect of the present invention is a sound propagation device for a vehicle, comprising a double wall consisting of an inner wall portion and an outer wall portion that are positioned outside the vehicle from a sound-generating portion that emits sound of a predetermined frequency and are spaced apart in the vehicle's interior and exterior directions, and an intermediate layer that is formed in an enclosed space between the inner wall portion and the outer wall portion and through which the sound passes.

[0010] According to this configuration, sound of a predetermined frequency emitted by the sound generating unit can be transmitted by resonance from the inner wall portion of the double wall through the intermediate layer to the outer wall portion, and can then be propagated to the outside of the vehicle from the outer wall portion. Therefore, the sound generated by the sound generating unit can be appropriately propagated from the inside of the vehicle to the outside of the vehicle without passing through the panel opening provided in the wall. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view of a vehicle on which a vehicle sound output device and a vehicle sound propagation device according to a first embodiment of the present invention are mounted. [Diagram 2] 1 is a configuration diagram of a vehicle sound output device including a vehicle sound propagation device of a first embodiment. [Diagram 3] This graph compares the relationship between sound frequency and transmission loss for a double-walled (shown by a solid line) and a single-walled (shown by a dashed line) system. [Figure 4] FIG. 11 is a configuration diagram of a vehicle sound output device including a vehicle sound propagation device according to a second embodiment. [Diagram 5] FIG. 11 is a configuration diagram of a vehicle sound output device including a vehicle sound propagation device according to a third embodiment. [Figure 6] 1 is a configuration diagram of a vehicle sound output device including a vehicle sound propagation device according to a first modified embodiment. FIG. [Figure 7] FIG. 11 is a configuration diagram of a vehicle sound output device including a vehicle sound propagation device according to a second modified embodiment. [Figure 8] 8 is an exploded perspective view of a vehicle sound output device including the vehicle sound propagation device shown in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, specific embodiments of the vehicle sound output device and the vehicle sound propagation device according to the present invention will be described.

[0013] [First embodiment] The vehicle sound output device 1 of this embodiment is a device mounted on a vehicle 3, and allows people around the vehicle to hear the sound generated by the sound generating unit. The vehicle sound propagation device 2 propagates the sound generated by the sound generating unit toward people around the vehicle. The vehicle 3 on which the vehicle sound output device 1 is mounted may be a vehicle in which an opening is provided in an exterior panel for taking in air into the engine compartment, but may also be an electric vehicle in which the exterior panel does not have the above opening, or even if the opening is provided, the opening has a relatively small opening area (see FIG. 1).

[0014] 2, the vehicle sound output device 1 includes a sound generating section 10, a double wall 20, and an intermediate layer 30. The vehicle sound propagation device 2 is a device obtained by removing the sound generating section 10 from the vehicle sound output device 1, and includes the double wall 20 and the intermediate layer 30.

[0015] The sound generating unit 10 is a device that emits a sound of a predetermined frequency outside the vehicle. The sound generating unit 10 may be a horn that emits a warning sound to people around the vehicle 3, an approach notification device that notifies people approaching the vehicle 3 of the approach, or a speaker that emits sound such as a human voice or the sound of a musical instrument. The sound generating unit 10 is disposed inside the exterior panel of the vehicle 3. The sound generating unit 10 is capable of emitting a sound with a sound pressure level that complies with laws and regulations. The sound generating unit 10 also emits a sound of a predetermined frequency.

[0016] The predetermined frequency of the sound generated by the sound generating unit 10 is, for example, a frequency between 20 Hz and 20,000 Hz, which is an audible sound range. The predetermined frequency of the sound generated by the sound generating unit 10 includes not only the basic frequency (fundamental frequency) of the sound generated by the sound generating unit 10, but also frequencies that are two or more positive multiples of the fundamental frequency. When the sound generating unit 10 is a horn, the fundamental frequency of the sound is set, for example, between 270 Hz and 600 Hz, such as 370 Hz, 400 Hz, 480 Hz, and 500 Hz. When the sound generating unit 10 generates an approach warning sound, the fundamental frequency of the sound is set, for example, between 20 Hz and 5,000 Hz.

[0017] The sound producing unit 10 is attached to a housing 11. The housing 11 is formed in a box shape (e.g., a rectangular parallelepiped shape) capable of housing the sound producing unit 10. The housing 11 is arranged on the vehicle 3 so that the sound produced by the sound producing unit 10 tends to travel outside the vehicle. The sound producing unit 10 is oriented so that the sound produced tends to travel outside the vehicle when the housing 11 is arranged on the vehicle 3.

[0018] The double wall 20 is a wall that separates the sound generating unit 10 from the outside of the vehicle. The double wall 20 is disposed on the vehicle outer side of the sound generating unit 10. The double wall 20 is composed of an inner wall portion 21 and an outer wall portion 22. The inner wall portion 21 and the outer wall portion 22 are disposed apart from each other in the vehicle inner / outer direction. That is, the inner wall portion 21 is disposed closer to the sound generating unit 10 than the outer wall portion 22, and the outer wall portion 22 is disposed farther from the sound generating unit 10 than the inner wall portion 21. A hollow space 23 is formed between the inner wall portion 21 and the outer wall portion 22. The double wall 20 transmits the sound of the sound generating unit 10 from the vehicle inner side to the vehicle outer side by resonance between the inner wall portion 21 and the outer wall portion 22.

[0019] The exterior wall portion 22 is an exterior panel or cover part that is the outermost shell of the vehicle 3 and faces the outside of the vehicle. The exterior wall portion 22 is formed in a plate shape with no or almost no openings. The exterior wall portion 22 is, for example, a grille, a bumper, a fender, a bonnet, a headlight cover, a pillar, a roof, a side mirror cover, etc. The exterior wall portion 22 is formed from a resin material or a metal material. The exterior wall portion 22 is attached and fixed to a structure 3a such as a frame, an exterior panel, or a cover provided on the vehicle 3. The exterior wall portion 22 is arranged so as to cover an opening 4 provided in the structure 3a.

[0020] The inner wall portion 21 is a plate-like member. The inner wall portion 21 is disposed on the vehicle inner side of the outer wall portion 22, and faces the outer wall portion 22 with an intermediate layer 30, which will be described in detail later, sandwiched between the inner wall portion 21 and the outer wall portion 22. The inner wall portion 21 can vibrate due to a sound of a predetermined frequency emitted by the sound generating portion 10. The vibration of the inner wall portion 21 due to the sound is transmitted to the outer wall portion 22 with the intermediate layer 30 acting as a spring. The outer wall portion 22 can vibrate in resonance with the vibration of the inner wall portion 21.

[0021] The inner wall portion 21 is provided on the bracket 40. The bracket 40 is attached to the back surface (inner surface) of the outer wall portion 22. The bracket 40 is formed of a resin material or a metal material. The material of the bracket 40 may be the same as the material of the outer wall portion 22. The inner wall portion 21 is formed with a thickness and material that allows it to vibrate due to the sound of the sound generating unit 10. The thickness of the inner wall portion 21 is, for example, 2 mm to 5 mm. The outer wall portion 22 is formed with a thickness and material that allows it to vibrate in resonance with the vibration of the inner wall portion 21. The thickness of the outer wall portion 22 may be the same as the thickness of the inner wall portion 21, for example, 2 mm to 5 mm. In this embodiment, the inner wall portion 21 is integrated with the enclosing portion 42 described later as a part of the bracket 40, but it may be provided separately from the bracket 40 and attached to the enclosing portion 42 as the bracket 40 to be integrated.

[0022] The bracket 40 has an inner wall portion 21, an attachment portion 41, and an enclosing portion 42. The attachment portion 41 is a through hole through which a fastener 50 such as a bolt or a screw passes for attaching the bracket 40 to the rear surface of the outer wall portion 22. The attachment portions 41 are provided at multiple locations on the periphery of the plate-shaped inner wall portion 21.

[0023] The outer wall portion 22 has a fixing portion 22a to which the mounting fixture 50 is fixed. The fixing portion 22a is formed on the back surface side of the outer wall portion 22. The fixing portion 22a is a mounting hole formed in a protruding portion 22b that protrudes from the back surface of the outer wall portion 22 toward the inside of the vehicle. The bracket 40 is attached to the outer wall portion 22 by the mounting fixture 50 penetrating the mounting portion 41 and being fixed to the fixing portion 22a of the outer wall portion 22.

[0024] The protrusion 22b is formed in an annular shape so as to follow the periphery of the inner wall portion 21. When the bracket 40 is attached to the outer wall portion 22, the hollow space 23 between the inner wall portion 21 and the outer wall portion 22 is surrounded all around by the annular protrusion 22b. In other words, the hollow space 23 is sealed by the front surface of the inner wall portion 21, the back surface of the outer wall portion 22, and the inner side surface of the protrusion 22b.

[0025] The surrounding portion 42 is a portion that surrounds the entire periphery of the housing 11 (particularly, the sound generating portion 10). The surrounding portion 42 extends in a cylindrical shape from the sound generating portion 10 side to the vehicle inner surface side of the inner wall portion 21. The surrounding portion 42 has a bottom wall portion that closes the cylindrical end on the sound generating portion 10 side, and an opening portion that opens the cylindrical end on the inner wall portion 21 side. The housing 11 is attached and fixed to the bottom of the vehicle inner end of the surrounding portion 42 so that the entire periphery of the housing 11 is surrounded by the cylindrical wall of the surrounding portion 42.

[0026] The housing 11 has a flange portion 11a extending radially outward from the outer circumferential surface. The flange portion 11a has an attachment portion 11b. The attachment portion 11b is a through hole through which a fastener 51 such as a bolt or a screw for attaching the housing 11 to the surrounding portion 42 passes. The flange portion 11a and the attachment portion 11b are provided at multiple locations around the entire circumference of the housing 11.

[0027] The surrounding portion 42 has a fixing portion 42a to which the mounting fixture 51 is fixed. The fixing portion 42a is formed on the surface side of the surrounding portion 42. The fixing portion 42a is a mounting hole formed in a protruding portion 42b that protrudes from the surface of the surrounding portion 42 toward the outside of the vehicle. The housing 11 is attached to the surrounding portion 42 by the mounting fixture 51 penetrating the mounting portion 11b and being fixed to the fixing portion 42a of the surrounding portion 42. The fixing portion 42a and the protruding portion 42b are provided in multiple locations on the surrounding portion 42 corresponding to the flange portion 11a and the mounting portion 11b of the housing 11.

[0028] The surrounding part 42 is attached and fixed to the inner wall part 21 and is integrated with it. With the housing 11 attached and fixed, the surrounding part 42 is detachably engaged with the inner wall part 21. When the surrounding part 42 is attached to the inner wall part 21 with the housing 11 attached and fixed to the surrounding part 42, the housing 11 and therefore the sound generating part 10 attached to the housing 11 are disposed in a space 49 sealed by the inner wall part 21 and the surrounding part 42. This sealed space 49 serves as a guide path that guides the sound generated by the sound generating part 10 to the double wall 20.

[0029] The surrounding covering portion 42 and the inner wall portion 21 have engaging portions 43, 44 that engage with each other. The engaging portion 43 of the surrounding covering portion 42 is an engaging protrusion for engaging the surrounding covering portion 42 with the engaging portion 44 of the inner wall portion 21. The engaging portion 43 is formed on the cylindrical side wall of the surrounding covering portion 42 so as to protrude radially outward from its outer circumferential surface. The engaging portion 44 of the inner wall portion 21 is an engaging hole with which the engaging portion 43 engages. The engaging portion 44 is formed on the back surface side of the inner wall portion 21. The engaging portion 44 is formed so as to penetrate radially into a protruding portion 45 that protrudes from the back surface of the inner wall portion 21 toward the inside of the vehicle. The engaging portion 43 of the surrounding covering portion 42 and the engaging portion 44 of the inner wall portion 21 are provided at multiple locations corresponding to each other.

[0030] The bracket 40 is attached to the outer wall 22 using a fastener 50 such as a bolt or a screw. However, as long as the bracket 40 is in close contact with the outer wall 22 to seal the hollow space 23, a double-sided tape fastening, heat welding, ultrasonic welding, or the like may be used instead of the above-mentioned attachment method. The housing 11 is attached to the surrounding portion 42 of the bracket 40 using a fastener 51 such as a bolt or a screw, but this attachment method may be replaced by a double-sided tape fastening, heat welding, ultrasonic welding, or the like. The surrounding portion 42 is attached to the inner wall 21 of the bracket 40 using the engaging portions 43 and 44 that engage with each other, but this attachment method may be replaced by a detachable screw fastening, or the like.

[0031] The intermediate layer 30 is an air layer between the inner wall portion 21 and the outer wall portion 22 of the double wall 20. In other words, the intermediate layer 30 is the hollow space 23 itself. The thickness (i.e., the width in the vehicle's inner / outer directions) or volume of the intermediate layer 30 is set in accordance with the frequency of the sound emitted by the sound generating portion 10 so as to generate a resonance transmission phenomenon (see FIG. 3) that transmits the sound from the inner wall portion 21 to the outer wall portion 22. Specifically, the intermediate layer 30 is determined according to the following formula (1).

[0032]

number

[0033] However, f rmd is the frequency [Hz] of the sound emitted by the sound generating unit 10, d is the thickness [mm] of the intermediate layer 30, and ρ is the density [kg / m 3 ], c is the sound speed [m / s] of the gas in the intermediate layer 30, and m1 is the surface density [kg / m 2 ], and m2 is the surface density [kg / m 2 Since the intermediate layer 30 is an air layer, ρ is 1.2 [kg / m 3 ] and c is 343.7[m / s].

[0034] Next, the operation of the vehicle sound output device 1 including the vehicle sound propagation device 2 will be described. The sound producing unit 10 produces a sound of a predetermined frequency. The sound of the predetermined frequency produced by the sound producing unit 10 propagates through the space 49 in the bracket 40 and reaches the inner wall portion 21. The sound that reaches the inner wall portion 21 is transmitted by resonance from the inner wall portion 21 through the intermediate layer 30 to the outer wall portion 22, and is propagated outside the vehicle beyond the outer wall portion 22. This makes it easier for people around the vehicle 3 to hear the sound produced by the sound producing unit 10 of the vehicle 3, and the sound produced by the sound producing unit 10 can be used to alert people.

[0035] In the above-described configurations of the vehicle sound output device 1 and the vehicle sound propagation device 2, sound emitted by the sound generating unit 10 disposed on the inside of the vehicle propagates to the outside of the vehicle through resonant transmission through the double wall 20. At this time, the sound insulation performance of the double wall 20 is significantly reduced. Therefore, sound of a predetermined frequency emitted by the sound generating unit 10 can be appropriately propagated from the inside of the vehicle to the outside of the vehicle without passing through an opening that allows sound to easily pass through.

[0036] For this reason, even in electric vehicles and the like in which no openings are provided in the exterior panels or cover parts (i.e., the exterior wall portion 22) of the vehicle 3, or which have openings but whose opening areas are small, the sound generation unit 10 can be positioned inside the vehicle so that people around the vehicle 3 can hear the sound of a specified frequency emitted by the sound generation unit 10. This eliminates the need to secure an opening that allows sound to easily pass through, and makes it possible to achieve both sound propagation and the freedom to mount the sound generation unit 10.

[0037] Moreover, the sound generating unit 10 is surrounded all around by the covering unit 42, and is disposed in a space 49 sealed by the inner wall unit 21 and the covering unit 42. In this structure, the sound generated by the sound generating unit 10 can be confined in the space 49 and is less likely to leak from the space 49, and most of the sound can reach the inner wall unit 21. Therefore, the sound generated by the sound generating unit 10 can be efficiently propagated to the double wall 20, and a resonant transmission phenomenon can be caused in the double wall 20 and the intermediate layer 30.

[0038] Moreover, the sound producing unit 10 is attached to the housing 11, and this housing 11 is attached and fixed to a bracket 40 attached to the outer wall portion 22 that constitutes the double wall 20. In other words, the sound producing unit 10 is fixed to the back surface of the double wall 20. In this configuration, the sound producing unit 10 can be disposed close to the double wall 20.

[0039] [Second embodiment] In the vehicle sound output device 1 of the first embodiment, the inner wall portion 21 and the surrounding portion 42 of the bracket 40 are engaged with each other to be integrated, and the sound generation unit 10 is attached to the surrounding portion 42 of the bracket 40 and disposed so as to face the inner wall portion 21 on the vehicle inward side of the inner wall portion 21. The sound generation unit 10 is also housed and attached in the housing 11, and thus the sound generation unit 10 is fixed to the double wall 20 side.

[0040] In contrast, in the vehicle sound output device 100 of this embodiment, as shown in Fig. 4, the sound producing unit 10 is disposed on the vehicle interior side relative to the inner wall portion 21, but is disposed relatively far away from the inner wall portion 21, and a guide path is formed between the sound producing unit 10 and the inner wall portion 21 to guide the sound emitted by the sound producing unit 10 to the double wall 20. Also, the sound producing unit 10 is fixed to a structure 3b located inside the vehicle 3, not on the double wall 20 side. In Fig. 4, the same components as those shown in Fig. 2 are denoted by the same reference numerals, and their description will be omitted or simplified.

[0041] The vehicle sound output device 100 includes a guide wall 110. The guide wall 110 is a guide wall that forms a guide path 111 that guides a sound of a predetermined frequency emitted by the sound producing unit 10 to the double wall 20. The guide wall 110 extends in a cylindrical shape from the sound producing unit 10 side to the vehicle inner surface side of the inner wall unit 21. When the sound producing unit 10 does not face the inner wall unit 21 as shown in FIG. 4, the guide wall 110 and the guide path 111 are formed in a curve from the sound producing unit 10 to the inner wall unit 21.

[0042] The guide wall 110 is attached to the rear surface of the inner wall portion 21 and is integrated with the inner wall portion 21. The guide wall 110 is attached to the inner wall portion 21 by claw fitting, bolt fastening, or the like. The sound generating unit 10 is attached to the inner structure 3b of the vehicle 3 via a mounting bracket 120 by bolt fastening or the like, without being attached to the guide wall 110. Note that the sound generating unit 10 may be disposed so as to enter and cover the inside of the guide path 111 from the sound inlet end of the guide wall 110 as shown in FIG. 4, as long as the sound it emits effectively propagates through the guide path 111, or may be disposed outside the guide path 111 from the sound inlet end of the guide wall 110.

[0043] In this vehicle sound output device 100, the sound of a predetermined frequency emitted by the sound generating unit 10 propagates through the guideway 111 in the guide wall 110 to reach the inner wall portion 21. The sound that reaches the inner wall portion 21 is resonantly transmitted from the inner wall portion 21 to the outer wall portion 22 through the intermediate layer 30, and is propagated outside the vehicle from the outer wall portion 22. Therefore, in the vehicle sound output device 100, it is possible to easily make the sound emitted by the sound generating unit 10 of the vehicle 3 heard by people around the vehicle 3, and it is possible to call attention using the sound emitted by the sound generating unit 10. Therefore, the sound of a predetermined frequency emitted by the sound generating unit 10 can be appropriately propagated from the inside of the vehicle to the outside of the vehicle without passing through an opening that makes it easy for sound to pass through, and the same effect as in the first embodiment can be obtained.

[0044] Furthermore, the sound generating unit 10 is disposed relatively far away from the inner wall portion 21 of the double wall 20, and the sound generated by the sound generating unit 10 is propagated through the guide path 111 formed by the guide wall 110 and guided to the double wall 20. Therefore, even when it is necessary to dispose the sound generating unit 10 away from the double wall 20, the sound generated by the sound generating unit 10 can be guided to the double wall 20 through the guide path 111 and transmitted through resonance.

[0045] In the second embodiment, the guide wall 110 is separate from the inner wall portion 21 and is attached to the rear surface of the inner wall portion 21 to be integrated with it. However, the present disclosure is not limited to this, and the guide wall 110 and the inner wall portion 21 may be integrally formed.

[0046] [Third embodiment] In the above-described second embodiment, the guide wall 110 is attached to the rear surface of the inner wall portion 21 without any gap, and the sound outlet end of the guide path 111 contacts the rear surface of the inner wall portion 21.

[0047] In contrast, in the vehicle sound output device 200 of this embodiment, as shown in Fig. 5, the guide wall 210 is disposed away from the rear surface of the inner wall portion 21, and a gap is formed between the sound outlet end of the guide path 211 and the rear surface of the inner wall portion 21. In Fig. 5, the same components as those shown in Figs. 2 and 4 are denoted by the same reference numerals, and their description will be omitted or simplified.

[0048] The vehicle sound output device 100 includes a guide wall 210. The guide wall 210 is a guide wall that forms a guide path 211 that guides a sound of a predetermined frequency emitted by the sound producing unit 10 to the double wall 20. The guide wall 210 extends in a cylindrical shape from the sound producing unit 10 side to the vehicle inner surface side of the inner wall unit 21. When the sound producing unit 10 does not face the inner wall unit 21 as shown in FIG. 5, the guide wall 210 and the guide path 211 are formed in a curve from the sound producing unit 10 to the inner wall unit 21.

[0049] The guide wall 210 is disposed away from the rear surface of the inner wall portion 21 toward the inside of the vehicle. The guide wall 210 is attached to the inner structure 3c of the vehicle 3 via the mounting bracket 220 by bolt fastening or the like. The gap distance of the guide wall 210 away from the rear surface of the inner wall portion 21 may be such that the sound emitted by the sound generating unit 10 and propagated through the guideway 211 effectively reaches the inner wall portion 21 and resonates and transmits through the double wall 20. The sound generating unit 10 is attached to the inner structure 3b of the vehicle 3 via the mounting bracket 120 without being attached to the guide wall 210. The sound generating unit 10 may be disposed so as to enter and cover the inside of the guideway 211 from the sound inlet end of the guide wall 210 as long as the sound it generates effectively propagates through the guideway 211, or may be disposed so as to be outwardly disposed from the sound inlet end of the guide wall 210 to the outside of the guideway 211 as shown in FIG. 5.

[0050] In this vehicle sound output device 200, the sound of a predetermined frequency emitted by the sound generating unit 10 propagates through the guideway 211 in the guide wall 210 to reach the inner wall portion 21. The sound that reaches the inner wall portion 21 is resonantly transmitted from the inner wall portion 21 to the outer wall portion 22 through the intermediate layer 30, and is propagated outside the vehicle from the outer wall portion 22. Therefore, in the vehicle sound output device 200, it is possible to easily make the sound emitted by the sound generating unit 10 of the vehicle 3 heard by people around the vehicle 3, and it is possible to call attention using the sound emitted by the sound generating unit 10. Therefore, the sound of a predetermined frequency emitted by the sound generating unit 10 can be appropriately propagated from the inside of the vehicle to the outside of the vehicle without passing through an opening that makes it easy for sound to pass through, and the same effects as those of the first and second embodiments can be obtained.

[0051] In the above first to third embodiments, the frequency of the sound generated by the sound generating unit 10 is set to a frequency within a predetermined range. However, the present invention is not limited to this, and the sound generated by the sound generating unit 10 may be a mixture of multiple frequencies within a predetermined range (for example, two frequencies of 400 Hz and 480 Hz). In this case, the sounds of the multiple frequencies may be generated simultaneously or separately in time from one sound generating unit 10, or may be generated from separate sound generating units 10 as shown in FIG. 6.

[0052] In addition, when a plurality of frequencies are generated from the sound generating unit 10 as described above, it is preferable that a plurality of sets of the double wall 20 and the intermediate layer 30 are provided. For example, as shown in FIG. 6, a first set A of the double wall 20A and the intermediate layer 30A and a second set B of the double wall 20B and the intermediate layer 30B are provided. In the set A, the double wall 20A and the intermediate layer 30A are configured to resonate and transmit only sounds of assigned frequencies. In the set B, the double wall 20B and the intermediate layer 30B are configured to resonate and transmit only sounds of assigned frequencies. Specifically, in the sets A and B, for example, the thicknesses of the intermediate layers 30A and 30B are configured to be different from each other according to the frequencies of the sounds to be generated.

[0053] 6 shows the sound producing section 10 in which the sound producing section 10A on the first set A side and the sound producing section 10B on the second set B side are provided separately. Also, in FIG. 6, the outer wall section 22 of the double wall 20A of the first set A and the outer wall section 22 of the double wall 20B of the second set B are shown as a common section.

[0054] 6, the sound generating units 10A and 10B in the first set A and the second set B emit sounds of corresponding frequencies, the double wall 20A and the intermediate layer 30A resonate and transmit only the sounds of the corresponding frequencies among the multiple frequencies, and the double wall 20B and the intermediate layer 30B resonate and transmit only the sounds of the corresponding frequencies among the multiple frequencies. In this configuration, sounds of different frequencies can be propagated from the inside of the vehicle to the outside of the vehicle on the first set A and the second set B, respectively.

[0055] In the first to third embodiments described above, the hollow space 23 between the inner wall portion 21 and the outer wall portion 22 (and thus the intermediate layer 30) is surrounded on its entire periphery by the protruding portion 22b formed in an annular shape on the back surface side of the outer wall portion 22. However, the present invention is not limited to this, and as shown in Figs. 7 and 8, the hollow space 23 and thus the intermediate layer 30 may be surrounded on its entire periphery by the protruding portion 21a formed in an annular shape on the front surface side of the inner wall portion 21.

[0056] The protruding portion 21a of the inner wall portion 21 protrudes in an annular shape from the peripheral portion of the surface of the inner wall portion 21 toward the back surface of the outer wall portion 22. This surrounds the entire circumference of the hollow space 23 and the intermediate layer 30. In order to ensure the airtightness of the hollow space 23 and the intermediate layer 30, it is preferable to place a cushioning member (cushion material) 60 between the tip of the protruding portion 21a of the inner wall portion 21 and the back surface of the outer wall portion 22. This configuration makes it possible to efficiently propagate the sound generated by the sound generating portion 10 to the double wall 20 while preventing it from leaking from the hollow space 23.

[0057] In the above modified embodiment, the inner wall 21 and the hollow cylindrical duct 70 that guides the sound generated by the sound generating unit 10 to the inner wall 21 may be attached and fixed to a structure (such as a so-called arrowhead) 22d provided on the back side of the outer wall 22. The attachment method may use a mounting fixture 52 such as a bolt or a screw. In this structure, the mounting fixture 52 passes through the mounting hole 21c of the flange 21b provided on the inner wall 21, the mounting hole 70b of the flange 70a provided on the duct 70, and the mounting hole 22e of the structure 22d of the outer wall 22, and is fastened to the spring nut 53.

[0058] In addition, in the mounting structure using the above-mentioned mounting fixture 52, in order to absorb vibrations transmitted between the inner wall portion 21 and the duct 70 (particularly vibrations from the inner wall portion 21 to the duct 70), a member with cushioning properties (cushion material) 61 may be disposed between the flange portion 21b of the inner wall portion 21 and the flange portion 70a of the duct 70. This configuration makes it difficult for vibrations to be transmitted between the inner wall portion 21 and the duct 70, thereby making it possible to prevent the vibrations from affecting the resonant transmission of the sound generated by the sound generating portion 10.

[0059] Furthermore, in the structure in which the hollow duct 70 guides the sound generated by the sound generating unit 10 to the inner wall 21 as described above, a cushioning member (cushioning material) 62 may be arranged on the inner surface of the duct 70 (for example, only one of the four cylindrical inner surfaces in the example shown in Figs. 7 and 8; however, it is preferable to target all four cylindrical inner surfaces) in order to prevent the duct 70 from vibrating due to the sound generated by the sound generating unit 10. With this configuration, it becomes possible to make it difficult for the duct 70 to vibrate due to the sound generated by the sound generating unit 10, and to efficiently guide the sound to the double wall 20.

[0060] In the above first to third embodiments, the intermediate layer 30 formed in the sealed hollow space 23 between the inner wall portion 21 and the outer wall portion 22 of the double wall 20 is an air layer. However, the present invention is not limited to this, and as long as the intermediate layer 30 allows the sound generated by the sound generating portion 10 to pass therethrough, the intermediate layer 30 may be a layer in which argon gas, liquid, or the like is sealed in the hollow space 23, or the intermediate layer 30 in which argon gas, liquid, or the like is sealed in a bag shape may be inserted into the hollow space 23.

[0061] The present invention is not limited to the above-described embodiment and modified forms, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0062] 1,100,200: vehicle sound output device, 2: vehicle sound propagation device, 3: vehicle, 10: sound generation section, 11: housing, 20: double wall, 21: inner wall section, 22: outer wall section, 23: hollow space, 30: intermediate layer, 40: bracket, 42: enclosing section, 110,210: guide wall, 111,211: guideway.

Claims

1. a sound generating unit that generates a sound of a predetermined frequency; a double wall including an inner wall portion and an outer wall portion that are disposed on a vehicle outer side and apart from the sound-producing portion and that are spaced apart from each other in a vehicle inside-outside direction; an intermediate layer formed in a sealed space between the inner wall portion and the outer wall portion and through which the sound is transmitted; A sound output device for a vehicle.

2. 2. The vehicle sound output device according to claim 1, further comprising a guide wall that extends cylindrically from the sound generating portion to a vehicle inner surface side of the inner wall portion and forms a guide path that guides the sound to the double wall.

3. The guide wall has a bottom wall portion that closes one of the cylindrical ends and an opening portion that opens the other of the cylindrical ends, the sound generating unit is attached to the bottom wall side of the guide wall so as to generate the sound toward the opening side of the guide wall, The vehicle sound output device according to claim 2 , wherein the guide path is sealed by the inner wall portion and the guide wall.

4. The sound output device for a vehicle according to claim 1 , wherein the intermediate layer has a thickness, density, or volume that causes a resonance transmission phenomenon of the sound from the inner wall portion to the outer wall portion.

5. The vehicle sound output device according to claim 1 , wherein the intermediate layer is an air layer.

6. the predetermined frequency includes a plurality of frequencies different from each other, The double wall and the intermediate layer are provided in a plurality of sets, The vehicle sound output device according to claim 1 , wherein each of the intermediate layers transmits the sound of a corresponding frequency among the plurality of frequencies.

7. 7. The vehicle sound output device according to claim 1, wherein the predetermined frequency includes a fundamental frequency determined between 270 Hz and 600 Hz.

8. a double wall including an inner wall portion and an outer wall portion, the double wall portion being disposed on the vehicle outer side and apart from a sound generating portion that generates a sound of a predetermined frequency and spaced apart from the sound generating portion in the vehicle inner / outer direction; an intermediate layer formed in a sealed space between the inner wall portion and the outer wall portion and through which the sound is transmitted; A sound propagation device for a vehicle comprising:

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