JP2011057000A - Acoustic resonance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the sound pressure with comparatively low frequency in a cabin and to improve the effect exerted particularly in a location where a passenger can hear the sound. <P>SOLUTION: The sound with comparatively low frequency in the cabin for which the passenger possibly feels as a noise is strongly dependent on the normal mode of vibration in the cabin. When the normal mode of vibration at a height in the vicinity of the head of an occupant seated in front seats 140A, 140B in the cabin is watched, the normal mode of vibration with a wavelength approximately twice the vehicular width of the cabin is generated in the vehicle width direction. Also, the position of an antinode of the sound pressure of the normal mode of vibration is in the vicinity of both side windows 153. Accordingly, when an resonating body is arranged so as to reduce the sound pressure or to increase the particle velocity with a location in the proximity of a riding area of the passenger among the locations that become an antinode of the sound pressure of the normal mode of vibration in the cabin being made an object to be controlled, an action caused by the normal mode of vibration can be inhibited, the sound pressure with comparatively low frequency in the cabin can be reduced, and the effect exerted particularly in the location where the passenger can hear the sound can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for attenuating the sound of a passenger compartment.

  As a technique for improving the quietness of a passenger compartment, Patent Document 1 discloses providing a sound absorbing material in a vehicle. Patent Document 1 discloses a sound absorbing structure in which a felt is attached to a duct provided inside a dash panel of a passenger compartment. Patent Document 2 discloses a plate / membrane vibration type sound absorbing structure that absorbs sound by a plate-like or membrane-like vibrating body and an air layer in a space behind the vibrating body.

JP 2001-97020 A JP 2006-11412 A

Even if the sound absorption structure disclosed in Patent Document 2 is applied to the technology disclosed in Patent Document 1, for example, the engine sound of a car, a relatively low frequency caused by tire roads or road noise caused by roads. It is not enough to attenuate the sound. Further, Patent Document 1 does not disclose that a person in the passenger compartment has a high sound absorption effect at a place where the person can actually hear the sound.
The present invention has been made in view of the above-described problems, and its object is to reduce the sound pressure of a relatively low frequency in the passenger compartment, and in particular, to provide an effect that is played in a place where a person in the passenger compartment can hear sound. Is to increase.

In order to achieve the above-described object, an acoustic resonance device according to the present invention is a resonator having an opening and a hollow region that communicates with the opening, and the hollow region passes through the opening. A resonance body provided in the vehicle so as to be connected to the passenger compartment, and depending on the position of the boarding region in the passenger compartment among the places where the sound pressure of the natural vibration state of the specific natural frequency in the passenger compartment becomes The sound pressure of the natural frequency at a predetermined place is reduced by the resonance of the resonator.
In the acoustic resonance apparatus according to the present invention, it is preferable that the resonance body reduce a sound pressure at least at a place closest to the boarding region among places where the sound pressure of the natural vibration mode having the natural frequency is antinode.

  The acoustic resonance apparatus according to the present invention is a resonator having an opening and a hollow region communicating with the opening, and the hollow region is connected to the vehicle compartment via the opening. The natural frequency of a place that is provided according to the position of the boarding region in the passenger compartment among the places that are provided with the resonator provided in the vehicle and become the antinodes of the sound pressure of the natural vibration mode of the specific natural frequency in the passenger compartment. The movement speed of the medium particles is increased by the resonance of the resonator.

  Further, in the acoustic resonance device according to the present invention, the natural frequency and the frequency of the vibration applied to the passenger compartment from the outside are different from each other, and the resonance frequency of the resonance body depends on the position of the riding area. The sound pressure of the frequency determined by the vibration and the frequency excited by the vibration may be set to be reduced by the resonance.

In the acoustic resonance apparatus according to the present invention, it is preferable that the natural vibration mode of the natural frequency is a primary natural vibration mode in which sound pressure is distributed in the vehicle width direction of the vehicle.
In the acoustic resonance device according to the present invention, the natural vibration mode of the natural frequency may be a secondary natural vibration mode in which sound pressure is distributed in the front-rear direction of the vehicle.
In the acoustic resonance apparatus according to the present invention, a seat for a passenger may be provided in the riding area, and the resonator may be provided in the seat.
In the acoustic resonance apparatus according to the present invention, the resonator may be provided on a ceiling facing the vehicle interior.
In the acoustic resonance apparatus according to the present invention, the resonator may be provided on a support column that supports the roof of the vehicle.
In the acoustic resonance apparatus according to the present invention, the resonator may be provided on a door facing the vehicle compartment.

  ADVANTAGE OF THE INVENTION According to this invention, the sound pressure of the comparatively low frequency of a vehicle interior can be reduced, and especially the effect played in the place where the person in a vehicle cabin can hear sound can be heightened.

1 is a perspective view showing a vehicle according to an embodiment of the present invention. It is a figure which shows typically the inside of the compartment of a vehicle. It is the figure which represented typically the external appearance of a board | membrane and a membrane resonator. FIG. 4 is a cross-sectional view of a plate / membrane resonator viewed from an arrow II-II in FIG. 3. It is a figure explaining the site | part in which the resonance body of a vehicle is provided. It is a figure explaining the content of a measurement test. It is a graph showing the result of a measurement test. It is a figure explaining the site | part in which a resonator is provided. It is a figure explaining the site | part in which a resonator is provided. It is sectional drawing which looked at the roof in FIG. 2 from arrow VIII-VIII. It is sectional drawing of a center pillar. It is a figure showing the cross section of a front seat. It is sectional drawing at the time of cut | disconnecting a front door by the plane orthogonal to a vehicle width direction. It is a figure showing the structure of the acoustic tube. It is a figure explaining the site | part in which a resonator is provided. It is a figure explaining the site | part in which a resonator is provided. It is sectional drawing at the time of cut | disconnecting a roof in the same direction as arrow VIII-VIII in FIG. It is sectional drawing which looked at the center pillar from arrow DD in FIG. It is a figure explaining the structure which provided the acoustic tube in the front door. It is a figure explaining the structure of a Helmholtz resonator. It is sectional drawing at the time of cut | disconnecting a roof in the same direction as arrow VIII-VIII in FIG. It is a graph showing the result of the experiment which investigates a noise reduction effect. It is a figure which shows an example of a structure of a pipe part. It is a figure explaining the resonator which concerns on the modification of this invention. It is the figure which showed the simulation result of normal incidence sound absorption coefficient.

Hereinafter, embodiments of the present invention will be described.
[A: First Embodiment]
First, a first embodiment of the present invention will be described.
(A-1) Configuration of Vehicle FIG. 1 is a perspective view showing a four-door sedan type vehicle 100 according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing the passenger compartment 105 of the vehicle 100. In the vehicle 100, a bonnet 101, four doors 150 serving as entrances and exits of a passenger compartment 105, and a trunk door 103 are attached to a chassis serving as a base of a vehicle body so as to be freely opened and closed. The chassis includes a base 104, a center pillar 120 that is a column extending upward from the base 104, a front pillar 130, a rear pillar 180, and a portion of the roof 110 supported by these pillars. A compartment 105 of the vehicle 100 is formed inside the door 150. The passenger compartment 105 is a room space where a passenger who is a person who gets on the vehicle 100 is present. In the passenger compartment 105, a rear package tray 220 is provided behind the vehicle 100 in the front-rear direction (shown in FIG. 2). The rear package tray 220 is a member that covers from the passenger compartment 105 a partition wall that partitions the passenger compartment 105 and the cargo compartment (that is, the trunk). In addition, the front of the vehicle 100 refers to the traveling direction of the vehicle 100, and the rear of the vehicle 100 refers to a direction opposite to the traveling direction of the vehicle 100.

  The passenger compartment 105 is provided with a boarding area, which is an area where a passenger should be in the passenger compartment 105. The boarding area of the passenger compartment 105 is an area in which the front seat 140 and the rear seat 190 are provided in the same manner as an automobile having a general structure. More specifically, the front seat 140 includes a front seat 140A as a passenger seat and a front seat 140B as an assistant driver seat. Note that when there is no need to particularly distinguish each of the front seats, they are collectively referred to as “front seat 140”. Thus, the boarding area in the passenger compartment 105 is an area where a passenger is seated, and is predetermined in the design stage of the vehicle 100 or the like. The four doors 150 include two front doors 150A facing the front seats 140A and 140B, respectively, and two rear doors 150B facing the rear seat 190. The door 150 is provided with a side window 153. As shown in FIG. 1, when the side window 153 is closed, the side window 153 is located in the upper region of the front door 150A.

(A-2) Configuration of Resonant Body The vehicle 100 is configured with an acoustic resonance device for attenuating low-frequency sound that reverberates in the passenger compartment 105. This acoustic resonance apparatus has a resonance body that is provided in the vehicle 100 and attenuates the sound of the passenger compartment 105 by resonating. The resonance body included in the acoustic resonance apparatus of this embodiment is a plate / membrane resonance body 1.

FIG. 3 is a diagram schematically showing the appearance of the plate / membrane resonator 1. 4 is a cross-sectional view of the plate / membrane resonator 1 as viewed from the direction of arrows II-II in FIG.
The configuration of the plate / membrane resonator 1 is roughly divided into a housing 10 and a vibrating portion 15. The housing 10 is a rectangular parallelepiped box-like member that is open on the entire upper surface side. The housing 10 has an opening 12 and a rectangular parallelepiped gas layer 13 as a hollow region communicating with the opening 12. The housing 10 is made of, for example, wood, but other materials such as synthetic resin and metal may be used as long as the material is relatively harder than the vibration unit 15. The vibration part 15 is a rectangular member having elasticity and formed in a plate shape or a film shape. The vibration part 15 is made of a material made of elastic material that generates elastic vibration, such as synthetic resin, metal, fiberboard, etc., or a material made of elastic material or a polymer compound in the form of a film. Is used. The vibration unit 15 is provided so that the region near the end of one surface thereof is supported by the housing 10 and closes the opening 12 of the housing 10. By closing the opening 12 with the vibration part 15, a closed gas layer 13 is formed inside the plate / membrane resonator 1. The gas layer 13 is a layer made of gas particles, and here is an air layer made of air molecules.

  The plate / membrane resonator 1 is arranged so that the gas layer 13 is connected to a space to be a target of sound attenuation. To be connected to a space means that the hollow region (in this case, the gas layer 13) of the resonator is located in a place where the sound pressure of the space is transmitted. When sound is generated in the space, the plate / membrane resonator 1 resonates according to the sound pressure of the sound. This resonance causes a difference between the sound pressure in the space and the pressure in the gas layer 13 of the plate / membrane resonator 1. The vibration unit 15 vibrates due to this pressure difference, and after the acoustic energy is consumed, the acoustic energy is re-radiated. With this action, the sound pressure is reduced in the space on the surface of the plate / membrane resonator 1 and in the vicinity of the surface of the vibrating portion 15.

  By the way, the frequency at which the sound pressure is reduced by the resonance of the plate / membrane resonator 1 is determined by the resonance frequency of the spring mass system formed by the mass component (mass component) of the vibration unit 15 and the spring component of the gas layer 13. This vibration of the spring mass system is called “piston vibration”. In addition, since the vibration part 15 has elasticity and its area is relatively small, in a system in which the support part restraint in the housing 10 acts on the vibration part 15, a bending system property due to elastic vibration is added. That is, the plate / membrane resonator 1 also includes the vibration part 15 that performs “flexural vibration” and the gas layer 13 behind the vibration part 15.

Next, setting conditions for the plate / membrane resonator 1 will be described.
First, the resonance frequency of piston vibration will be described. The density of air (medium) is ρ ₀ [kg / m ³ ], the speed of sound is c ₀ [m / s], the density of the vibrating body is ρ [kg / m ³ ], and the thickness of the vibrating body is t [ m] and the thickness of the air layer is L [m], the resonance frequency f of the piston vibration satisfies the relationship of the following formula (1).

Next, the resonance frequency of bending vibration will be described. The shape of the vibration part 15 is rectangular, the length of one side is a [m], the length of the other side is b [m], the Young's modulus of the vibration part is E [Pa], and the Poisson's ratio of the vibration part is σ [−]. When the mode orders p and q are positive integers, both resonance frequencies f including the bending vibration generated in addition to the piston vibration satisfy the relationship of the following formula (2). In the field of architectural acoustics, the resonance frequency f thus obtained is also used for acoustic design.

  As described above, the plate / membrane resonator 1 generates resonance caused by piston vibration and resonance caused by bending vibration. However, they are not generated independently, and when the frequencies of the resonances are close to each other, the resonance of the spring mass system and the resonance of the bending system behave in combination, and the plate / membrane resonator 1 The resonance frequency is determined. On the other hand, if the resonance frequency of the spring mass system and the resonance frequency of the bending system are relatively separated from each other, each resonance system behaves independently although it affects each other. As a result, the fundamental vibration of the bending system is coupled with the spring component of the gas layer behind, and a vibration having a large amplitude is excited in the band between the resonance frequency of the spring mass system and the fundamental frequency of the bending system, and the sound pressure is reduced. The amount of attenuation increases.

With the above operation, the plate / membrane resonator 1 is suitable in that a relatively low resonance frequency is set and the sound pressure in a band centered on the frequency is reduced. More specifically, the inventors set the value of the fundamental vibration frequency of the bending system as fa (= (1 / 2π) · ((p / a) ² + (q / b) ² ) · (π ⁴ Et ³ / ( 12ρt (1-σ ² ))) ^1/2 ) and the value of the resonance frequency of the spring mass system is fb represented by the above equation (1), the relationship of the following equation (3) is satisfied. When the parameters of the plate / membrane resonator 1 are set, the sound pressure can be sufficiently reduced even in a relatively low frequency band.
0.05 ≦ fa / fb ≦ 0.65 (3)

  As a result, the fundamental vibration of the bending system is coupled to the spring component of the gas layer behind, and a vibration having a large amplitude is excited in a band between the fundamental resonance frequency of the piston vibration and the fundamental resonance frequency of the bending vibration ( The fundamental resonance frequency fa of the bending vibration fa <the peak frequency f of the sound pressure attenuation amount <the basic resonance frequency fb of the piston vibration, and a resonance phenomenon occurs. As a result, a reflected wave having an opposite phase is radiated from the plate / membrane resonator 1, and the sound pressure is reduced on the surface of the vibrating portion 15.

Further, when the above parameters of the plate / membrane resonator 1 are set so as to satisfy the relationship of the following formula (4), the frequency at which the sound pressure reduction amount reaches a peak is higher than the resonance frequency of the piston vibration. Small enough.
0.05 ≦ fa / fb ≦ 0.40 (4)
For example, in order to sufficiently reduce the sound pressure at 160 to 315 Hz (1/3 octave center frequency), the parameters of the plate / membrane resonator 1 are set to the following values. ρ ₀ = 1.225 [kg / m ³ ], c ₀ = 340 [m / s], ρ = 940 [kg / m ³ ], t = 0.0001 [m], L = 0.03 [m] A = b = 0.1 [m], E = 1.0 [GPa], σ = 0.4, p = q = 1.

(A-3) Location of Resonant Body Next, the location of the resonator body will be described.
FIG. 5 is a diagram for explaining a method of selecting the installation location of the plate / membrane resonator 1. FIG. 5A is a diagram illustrating a state in which the passenger compartment 105 is viewed from the obliquely rear side with the front seat 140A as the center. FIG. 5B is a graph showing an example of a natural vibration state (also referred to as a normal mode) distributed in the vehicle width direction in the passenger compartment 105. This graph shows the sound pressure distribution of the primary natural vibration mode of a standing wave (also called an axial wave) that is a natural vibration mode in a one-dimensional mode and in which the sound pressure is distributed in the vehicle width direction. . The wavelength of this axial wave is almost twice the vehicle width. This natural vibration state is determined by the vehicle width of the passenger compartment 105 and has a relatively low natural frequency of 167 Hz. In the graph of FIG. 5 (b), the horizontal axis represents the position on the dotted line H shown in FIG. 5 (a), at a height near the head (ear) of the passenger seated on the front seat 140. It represents the position in the vehicle width direction. The vertical axis represents the sound pressure level of the primary natural vibration mode.

  The inventors considered that the sound of a relatively low frequency such as 170 Hz, which can be felt as noise by the passenger in the passenger compartment 105, strongly depends on the mode of the natural vibration mode. In general, in a diffuse sound field, many natural vibration modes are generated densely in the target frequency band, so that the sound pressure is uniformly distributed in the sound field, and at each position of the sound field on the frequency axis. Shows a uniform sound pressure distribution. On the other hand, in a sound field in a relatively small space such as the passenger compartment 105, a natural vibration state that is relatively difficult to attenuate is generated. That is, the vehicle interior 105 can be said to be a sound field in which each natural vibration state is present on the frequency axis in an isolated manner. Further, in the low frequency natural vibration mode, the distribution of the antinodes of the sound pressure in the passenger compartment 105 is sparse, so that an antinode of the sound pressure appears at a specific place in the sound field, and the sound pressure at that place is Is particularly high compared to other places. Furthermore, the isolated natural vibration mode is mainly a one-dimensional mode (axial wave) natural vibration mode, and its acoustic energy is large and hardly attenuated. This is because the number of times a sound wave enters the wall surface per unit time is smaller than in other modes, and the acoustic energy absorbed by the wall surface is small.

  In such a sound field, when a sound with a specific natural frequency is attenuated, a place where the sound pressure of the natural vibration state of the natural frequency is a control target is controlled, and the sound pressure at the control target place is reduced. The inventors have found that low frequency sound can be effectively reduced in the entire sound field. That is, by setting the antinode of the sound pressure of the natural vibration mode as a control target for reducing the sound pressure, the action due to the natural vibration mode can be weakened. Note that as a configuration for reducing the sound pressure, a resonator can be used, and the opening of the resonator may be positioned at or near the antinode of the sound pressure to be controlled. The vicinity means a distance that can reduce the sound pressure at the place of the antinode of the sound pressure. For example, the distance is sufficiently small with respect to the wavelength of the sound having a specific natural frequency for which the sound pressure is to be reduced, for example, within the distance of 1/6 of the wavelength.

In order to confirm that the sound pressure at a low frequency in the sound field is reduced by the above action, the inventors performed a measurement test described below.
FIG. 6 is a diagram for explaining the contents of the measurement test, and schematically shows an example of a natural vibration state in which sound pressure is distributed in the height direction of a rectangular parallelepiped sound field. FIG. 6 shows a secondary natural vibration state, which is a relatively low natural frequency of 158 Hz from the height direction dimension of the sound field. In this figure, a hatched area indicates a place where the sound pressure becomes a maximum or a place near the maximum, and indicates a place where the sound pressure becomes an “antinode”. On the other hand, the area indicated by the hatching of the vertical line represents a place where the sound pressure is minimal or close to the minimum, and represents a place where the sound pressure becomes a “node”. Areas other than these, and the area represented by the color of the paper surface, indicate a place where the sound pressure is moderate. The natural vibration mode shown in FIG. 6 was obtained by calculation of a sound field simulation using a finite element method (FEM).

  As evaluation positions for measuring the sound pressure of the sound field, evaluation positions “1” to “15” indicated by circles in FIG. 6 are determined. And the microphone for sound collection was installed in each of these evaluation positions. The evaluation positions “1” to “9” are positions along a ridge line extending in the height direction of the sound field, and these evaluation positions are determined at approximately equal intervals. The evaluation positions “9” to “15” were positions along a ridge line extending in the width direction along the floor surface of the sound field. Each of these evaluation positions was also set at almost equal intervals. The evaluation position “9” is located at the corner of the sound field, and the sound source was placed at the corner farthest from the evaluation position.

  FIG. 7 is a graph showing the results of the measurement test, in which sounds emitted from a sound source are picked up by microphones provided at respective evaluation positions, and sound pressures obtained from the sound pickup results are shown. In the graph of FIG. 7, the horizontal axis represents the evaluation positions “1” to “15”, and the vertical axis represents a 160 Hz band (in this specification, a 1/3 octave band centered on 160 Hz). ) Sound pressure [dB]. In the graph, the solid line represents the result when the place where the sound pressure of the natural vibration state becomes the “antinode” is controlled and the sound pressure at that place is reduced by resonance of the resonator. Here, four acoustic tubes are arranged at four corners (ridge lines) of the sound field on a horizontal plane including the evaluation position “5”. In addition, here, an acoustic tube having one end opened and the other end closed is used, and the openings connected to the cavity of the acoustic tube are disposed at the four corners. The resonance frequency of the acoustic tube was set to resonate at a resonance frequency in the 160 Hz band. In the graph of FIG. 7, a broken line represents a result in a case where the sound pressure at the place where the sound pressure “node” of the natural vibration state is controlled is reduced by resonance of the resonator. Here, the acoustic tube having the above-described configuration is arranged in the same manner as described above on a horizontal plane including the evaluation position “7”. In the graph, the alternate long and short dash line represents the measurement result when no acoustic tube is arranged.

  As shown in FIG. 7, when the “antinode” of the sound pressure of the natural vibration state at the evaluation position “5” is set as the control target, the evaluation position “5”, which is the evaluation position closest to the opening of the acoustic tube, is used. Has a particularly low sound pressure (approximately 62 dB). In addition, the sound pressures at the evaluation positions “3”, “4”, “6”, and “7” that are close to the evaluation position “5” are about 90 dB, compared with the case where no acoustic tube is installed. Is low. In addition, even at the evaluation positions “8” to “15” located away from the acoustic tube, there is a difference in sound pressure of about 20 dB as compared with the measurement result when the acoustic tube is not installed. From these results, by making the sound pressure “antinode” of the natural vibration state a control object, the sound pressure in the vicinity is greatly reduced, and the sound is also emitted at a place away from the antinode position of the sound pressure of the control object. It can be seen that the pressure is reduced. Therefore, although the silence was improved in the entire sound field by the arrangement of the acoustic tube of the above aspect, it was confirmed. Hereinafter, this action may be expressed as “mode suppression”, “mode suppression”, or the like.

  On the other hand, when the location of the sound pressure “node” of the natural vibration state at the evaluation position “7” is set as the control target, the sound pressure at the evaluation position “7” closest to the opening of the acoustic tube is low. (Approximately 76 dB). However, the other evaluation positions are not so effective even when compared with the measurement results when the acoustic tube is not installed. From this result, even if the “node” of the sound pressure in the natural vibration mode is set as the control target, it is insufficient in reducing the sound pressure of the entire sound field, and the effect of suppressing the mode is hardly obtained.

Again, FIG. 5 will be described.
As shown in FIG. 5 (b), focusing on the primary natural vibration state in which the sound pressure is distributed in the vehicle width direction of the passenger compartment 105, the heads (ears) of the passengers seated in the front seats 140A and 140B. The inventors have found that a sound pressure belly appears near the height. The location of the antinode of this sound pressure is near both ends in the vehicle width direction of the passenger compartment 105, and is quite close to the positions of the side windows 153 of both front doors 150A. The wavelength of this natural frequency is approximately twice the vehicle width of the passenger compartment 105 as described above. For example, the wavelength of the natural frequency of 167 Hz is about 2.0 m, but the vehicle width of the passenger compartment 105 is, for example, about 1.0 m for a normal automobile.

  By the way, the location of the antinode of the sound pressure of the natural vibration state that appears in the vicinity of the side window 153 in the passenger compartment 105 is not necessarily the one that appears only by the standing wave (axial wave) propagating in that direction. The antinode of this sound pressure is estimated to appear due to an axial wave (one-dimensional mode natural vibration) in which the sound pressure is distributed in the vehicle width direction. Strictly speaking, the front and rear direction of the vehicle 100 (illustrated in FIG. 2). ) Is also related to the axial wave in which the sound pressure is distributed, and it may be caused by a so-called tangential wave (two-dimensional mode natural vibration). In addition, an axial wave in which sound pressure is distributed in the height direction of the passenger compartment 105 may be associated with a so-called diagonal wave (three-dimensional mode natural vibration). Regardless of the natural vibration, it must be the fact that a sound pressure antinode of natural vibration appears near the front seat 140 and the side window 153.

  In the passenger compartment 105, a plurality of natural vibration modes isolated on the frequency axis are generated in a relatively low frequency band, particularly 160 Hz band, and a sound pressure distribution of an actual sound field is formed. In view of this, the inventors have found that if the mode of the natural vibration mode (the mode shown in FIG. 5B) in which the sound pressure is distributed in the vehicle width direction is suppressed, the noise reduction effect in the passenger compartment 105 is high. Discovered. Therefore, by setting the antinodes of the sound pressure of the natural vibration state determined according to the position of the boarding area, and the antinodes of the sound pressure of the natural vibration state appearing in the vicinity of the front seat 140 and the side window 153, In particular, the effect played by the rider at the place where the sound is heard can be particularly enhanced. More specifically, considering the interior specifications of a vehicle having a general structure, the front seat 140 and the vicinity of the front seat 140 in the passenger compartment 105 are located near the place where the sound pressure is increased. It is preferable to provide a resonator on the wall.

  The place where the sound pressure of the natural vibration state in the passenger compartment 105 depends on the material and shape of the passenger compartment 105, and therefore measurement is possible without actually running the vehicle 100. . For example, a measurement sound having a preset frequency is emitted from a speaker provided in a passenger compartment of a general vehicle, and the emitted measurement sound is collected by microphones provided in various places in the passenger compartment. If the sound pressure at each position is obtained from the result, a sound pressure distribution as shown in FIG. 5B can be obtained. In addition, the shape and dimensions of the passenger compartment are often similar to some extent regardless of the type of vehicle. Therefore, in various types of vehicles, there is a natural vibration state in the vicinity of the front seat, which is the riding area. It seems that the belly of sound pressure appears.

(A-4) Configuration of Cabin 105 Next, the configuration of the portion of the cabin 105 where the plate / membrane resonator 1 is provided will be described. The plate / membrane resonator 1 provided in the passenger compartment 105 is assumed to have set conditions so that the mode can be suppressed with respect to the natural vibration state having a natural frequency of approximately 160 Hz. Here, the resonance frequency of the plate / membrane resonator 1 is set to substantially coincide with its natural frequency.

FIG. 8 is a perspective view showing the vehicle 100, and FIG. 9 is a view showing a state when the passenger compartment 105 is viewed from the obliquely rear side with the front seat 140A as a center. The plate / membrane resonator 1 is provided at each position shown in FIGS. Specifically, the portions where the plate / membrane resonator 1 is provided here are the roof 110, the center pillar 120, the front pillar 130, the front seat 140, and the front door 150A. Among these, the roof 110, the center pillar 120, the front pillar 130, and the front door 150 </ b> A are examples of wall portions that constitute the vehicle interior 105. Each plate / membrane resonator 1 is a position where the sound pressure of the antinode of the sound pressure to be controlled can be reduced, more specifically, a sufficiently small distance from the antinode to the wavelength of a specific natural frequency. (For example, a place within a distance of 30 cm). Further, the plate / membrane resonator 1 provided in each of these parts is provided such that the gas layer 13 is connected to the passenger compartment 105 through the opening 12.
In the following description, “upper side” means the upper side with respect to the height direction of the passenger compartment 105, and “lower” means the lower side with respect to the height direction of the passenger compartment 105. “Left side” means the left side with respect to the traveling direction of the vehicle 100, and “Right side” means the right side with respect to the traveling direction of the vehicle 100. A side window 153, which will be described later, is located when the window is closed, and the height of the side window 153 substantially coincides with the vicinity of the height of the passenger sitting on the front seat 140.

(A-4-1) Roof 110
First, the configuration of the roof 110 will be described. FIG. 10 is a cross-sectional view of the roof 110 of the vehicle 100 in FIG.
As shown in FIGS. 8 and 10, the plate / membrane resonator 1 is provided in a portion (ceiling portion) of the roof 110 that is almost directly above the riding area where the front seats 140 </ b> A and 140 </ b> B are provided. Here, the three plate / membrane resonators 1 are arranged in a line in the longitudinal direction of the vehicle 100. The reason why the plate / membrane resonator 1 is provided on the roof 110 is that the antinode of the sound pressure to be controlled appears in a relatively high place near the side window 153 of the front door 150A. The position in the vehicle width direction is determined so that the position of the vibration part 15 of the plate / membrane resonator 1 is as close to the side window 153 as possible.

  The roof 110 is attached to a part of a chassis that serves as a base of the vehicle 100, and has a roof inner panel 114 formed of, for example, polypropylene resin. The roof inner panel 114 includes a base material 111 formed of, for example, a wood fiber board. A surface material 112 formed of a cloth material that transmits sound pressure is provided on the side of the vehicle interior 105 of the base material 111. The plate / membrane resonator 1 is fitted into a recess 113 provided on the upper surface of the substrate 111 and is fixed to the roof inner panel 114 by adhesion, for example. In addition, about the structure which concerns on fixation of the resonance body with respect to the roof inner panel 114, you may fix using fixing tools, such as a screw | thread, a nut, and a belt other than adhesion | attachment, and the structure in particular is not ask | required. The plate / membrane resonator 1 is attached to the base material 111 so that the vibration part 15 faces the space of the passenger compartment 105 through the surface material 112.

  Further, as shown in FIG. 10, the plate / membrane resonator 1 fitted and fixed in the recess 115 is in the vicinity of the end in the vehicle width direction of the roof inner panel 114, and further to the side window 153. It is provided in the close and inclined ceiling part. More specifically, as shown in FIG. 9, the plate / membrane resonator 1 is positioned near the back of the assist grip 200 provided in the ceiling portion of the driver seat / passenger seat side of an automobile having a general structure. Provided. If the plate / membrane resonator 1 is provided at this location, the vibration section 15 is located at a location very close to the side window 153, so that the effect of reducing the sound pressure at the antinode location of the sound pressure to be controlled is achieved. Can be increased. Therefore, the mode can be effectively suppressed by arranging the plate / membrane resonator 1 on the roof 110.

(A-4-2) Center pillar 120 and front pillar 130
Next, the structure of the center pillar 120 and the front pillar 130 will be described.
FIG. 11 is a diagram illustrating a cross section when the center pillar 120 of the vehicle 100 in FIG. 2 is cut in a direction perpendicular to the extending direction. The center pillar 120 includes a center pillar outer panel 121 that forms a part of the chassis, and a center pillar inner panel 122 that is attached to the center pillar outer panel 121 by pins 122A. A surface material 123 made of a cloth material that transmits sound pressure is provided on the side of the cabin 105 of the center pillar inner panel 122.

The plate / membrane resonator 1 is attached so that the vibrating portion 15 faces the center pillar inner panel 122. A plurality of holes 124 are formed in the center pillar inner panel 122. With this configuration, the sound generated on the passenger compartment 105 side reaches the position of the vibration unit 15 through each hole 124. As can be seen from FIG. 9 and the like, the center pillar 120 is located close to the front seat 140 and the front door 150A. Therefore, by disposing the plate / membrane resonator 1 on the center pillar 120, the mode of the passenger compartment 105 can be effectively suppressed.
As shown in FIG. 9, the plate / membrane resonator 1 is also provided on the front pillar 130, but the configuration related to the attachment can be the same as that of the center pillar 120. Since the front pillar 130 is also in a position close to the front seat 140 and the front door 150A, the mode of the passenger compartment 105 can be effectively suppressed by arranging the plate / membrane resonator 1 on the front pillar 130. it can.

(A-4-3) Front seat 140
Next, the configuration of the front seat 140 will be described.
FIG. 12 is a diagram illustrating a cross section of the front seat 140. 12A is a cross-sectional view of the front seat 140 viewed from the arrow AA in FIG. 9, and FIG. 12B is the front seat 140 viewed from the arrow BB in FIG. It is sectional drawing which looked at. As for the front seat 140, the entire surrounding space is the passenger compartment 105.
The configuration of the front seat 140 is roughly divided into a headrest 141 and a seat back 142. The headrest 141 is attached to the seat back 142 by inserting a leg portion (not shown) into the seat back 142. The headrest 141 is a member on which the rear head of the rider seated on the front seat 140 is placed, and supports the rider's head. In the headrest 141, for example, a low-resilience urethane foam is packed as a core material in a headrest side bag portion 143 made of a flexible material such as a leather material or a synthetic leather material. The headrest side bag portion 143 is covered with a headrest cover 144. Also in the seat back 142, for example, urethane foam is packed as a core material in the seat back side bag portion 145, and the surface thereof is covered with the seat back cover 146. The headrest cover 144 and the seat back cover 146 are formed of a cloth material that transmits sound pressure.

  As shown in FIG. 12A, in the headrest 141, the plate / membrane resonator 1 is provided inside the headrest 141 so that the vibration portion 15 is located on each of two side surfaces facing the vehicle width direction of the passenger compartment 105. It has been. As described above, the position of the vibration part 15 is as close as possible to the position of the vibration part 15 because it is near the head of the passenger sitting on the front seat 140 and the sound pressure antinode of the natural vibration state is located near the side window 153. In order to approach the place, the plate / membrane resonator 1 is provided in this manner. In addition, the vibration part 15 faces the compartment 105 via the headrest cover 144, and is not easily seen by the passenger. Further, the plate / membrane resonator 1 is fixed to the headrest 141, and is fixed to, for example, a leg (not shown) or a frame (not shown) for attaching the headrest 141 to the seat back 142.

As shown in FIG. 12 (b), in the seat back 142, a vibrating portion is provided on the surface facing the upper side and the side surface facing the vehicle width direction (right side and left side) (more preferably near the height of the side window 153). The plate / membrane resonator 1 is provided so that 15 is located. The vibration unit 15 faces the passenger compartment 105 through the seat back cover 146, but is not easily seen by a passenger in the passenger compartment 105. The plate / membrane resonator 1 is fixed to the frame of the seat back 142 so that the position thereof does not move. As described above, the mode of the passenger compartment 105 can be effectively suppressed by providing the plate / membrane resonator 1 in the front seat 140 so that the vibrating portion 15 is as close as possible to the side window 153. In particular, since the front seat 140 is a member provided in the boarding area, the vibration part 15 can be arranged at a position close to the head of the rider, and the sound pressure at the place where the rider listens to the sound is possible. It can be expected that the effect of reducing this will be particularly enhanced.
Note that a seat in which the headrest 141 and the seat back 142 are integrally formed may be used. In this case as well, the plate / membrane resonator 1 similar to the above can be arranged.

(A-4-4) Front door 150A
Next, the configuration of the front door 150A will be described. In this embodiment, it is assumed that the plate / membrane resonator 1 is provided on the front door 150A, but the plate / membrane resonator 1 is not provided on the rear door 150B.

FIG. 13 is a diagram illustrating a cross section when the front door 150A is cut along a plane orthogonal to the vehicle width direction.
The front door 150 </ b> A has a door base material 151. A side window 153 is provided on the door base material 151 so as to be movable in the vertical direction with respect to the door 150. A surface material 154 formed of a cloth material that transmits sound pressure is provided on the side of the vehicle interior 105 of the door base material 151. The door base material 151 has a glass housing wall 151A that forms a housing portion that houses the side window 153 when the window is opened. In the door base material 151, a space S is formed closer to the vehicle interior 105 than the glass housing wall 151A. The plate / membrane resonator 1 is provided on the door base material 151 so that the vibration part 15 faces the space S. The door base material 151 is provided with a plurality of holes 155 that allow the space S and the passenger compartment 105 to pass therethrough.

  The sound generated on the side of the passenger compartment 105 enters the space S through the holes 155, so that the sound pressure can be reduced at the antinodes of the sound pressure to be controlled by the resonance of the plate / membrane resonator 1. it can. In the front door 150A, since the side window 153 is located on the upper side, the installation location of the plate / membrane resonator 1 is determined so that the vibration part 15 is located as close as possible. In this example, the plate / membrane resonator 1 is not provided near the floor surface, and the plate / membrane resonator 1 is provided relatively above the space S.

In the first embodiment described above, the roof 110, the center pillar 120, and the front pillar, which are the front seat 140 provided in the riding area of the passenger compartment 105 and the wall portion of the passenger compartment 105 adjacent to the passenger area. 130 and the front door 150A are provided with the plate / membrane resonator 1 to constitute an acoustic resonance device. In the passenger compartment 105, the place where the sound pressure of the natural vibration state with a relatively low natural frequency is located is the vicinity of the front seat 140 (particularly, the height near the head of the passenger) and the side of the front door 150A. Located near window 153. Therefore, if the plate / membrane resonator 1 is installed so that the antinodes of the sound pressure are controlled, the mode of the passenger compartment 105 can be effectively suppressed. In this embodiment, since the sound pressure antinode of the natural vibration state that appears in the vicinity of the front seat 140 (side window 153) is controlled, the plate / membrane resonator 1 has the natural vibration state of a specific natural frequency. It can be said that the sound pressure at least the place closest to the boarding area is reduced among the places where the sound pressure becomes antinode.
With the above configuration, the sound pressure at a relatively low frequency in the passenger compartment 105 can be reduced to improve the overall quietness, and in particular, the effect of being played in a place where a person in the passenger compartment can hear the sound can be enhanced.

[B: Second Embodiment]
Next, a second embodiment of the present invention will be described. In the second embodiment, the resonance body provided in the passenger compartment 105 is an acoustic tube, and the basis for selecting the configuration of the vehicle 100 and the installation location is the same as that of the first embodiment. In the description of the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the corresponding components are denoted by the symbol “a” at the end of the reference symbols, and the descriptions thereof are appropriately described. Omitted.

(B-1) Structure of Resonator First, the structure of the resonator provided in the vehicle 100 of this embodiment will be described. In this embodiment, the acoustic tube 2 is used as an example of a resonator. That is, in this embodiment, the resonance body included in the acoustic resonance apparatus is the acoustic tube 2.
FIG. 14 is a diagram illustrating a configuration of the acoustic tube 2 as an example of a resonator.
FIG. 14A is a diagram schematically showing the appearance of the acoustic tube 2. As shown in FIG. 14A, the acoustic tube 2 has a configuration in which a plurality of (for example, five) tubular members 21 (21-1 to 21-5) are arranged in a row in a direction perpendicular to the extending direction. have. These tubular members 21 are configured so as to be integrated by a fixing tool, adhesion, or the like. Each tubular member 21 is formed such that a material such as metal or synthetic resin is tubular. The tubular member 21 is a so-called one-end-opened tubular member (closed tube) having an opening 23 and a hollow region 25 communicating with the opening 23. One end portion of the tubular member 21 is closed to become a closed portion 22, and the other end portion becomes an opening portion 23. By aligning the positions of the openings 23 in the respective tubular members 21, the openings 23 are arranged adjacent to each other. The neck portion (that is, the opening 23 or the vicinity thereof) of the opening 23 of each tubular member 21 has air permeability such as glass wool, cloth, gauze, etc., and is closed with a flow resistance material 24 having flow resistance. Good. In order to reduce the sound pressure in the space, it is desirable to select and use an appropriate flow resistance material 24.

Next, the effect | action which concerns on the reduction of the sound pressure played with the acoustic tube 2 is demonstrated.
FIG. 14B is a view showing a cross section of two adjacent tubular members 21-j and 21-k (k = j + 1) in the acoustic tube 2 shown in FIG. The length of the hollow region 25 of the tubular member 21-j is L1, and the length of the hollow region 25 of the tubular member 21-k is L2. Here, the lengths of all the hollow regions 25 in the extension direction are equal ( That is, L1 = L2). When the sound wave from the passenger compartment 105 enters the position of the opening 23, the sound wave enters the hollow region 25 from the openings 23-j and 23-k and is closed at the other closed portions 22-j and 22-k. It is reflected and emitted again from the openings 23-j and 23-k. At this time, a sound wave having a wavelength λc (L1 = L2 = λ / 4) corresponding to four times the lengths L1 and L2 of the hollow region 25 creates standing waves S1 and S2, and the vibration of the tubular member 21 is repeated while the vibration is repeated. Energy is consumed by friction on the inner wall surface and viscous action between gas molecules at the openings 23-j and 23-k, and the sound pressure is reduced near the opening 23 around the wavelength λc. Here, L1 = L2 = 0.53 m and λc = 2.12 m.
The acoustic tube 2 is arranged so that the hollow region 25 is connected to a space that is a target of sound attenuation. Thereby, sound enters the opening 23 of each tubular member 21, the acoustic tube 2 resonates, and the sound pressure is reduced in the vicinity thereof. Here, the resonance frequency f is for reducing the sound pressure in a 160 Hz band, for example. In this case, for example, the length in the extension direction of the hollow region 25 may be set so as to be ¼ of the wavelength of a sound wave having a frequency of 160 Hz. In this case, for example, the length of the hollow region 25 in the extension direction is set to 40 cm to 80 cm.

In addition, the sound waves reflected by the closing portions 22-j and 22-k and emitted from the openings 23-j and 23-k are diffracted by the openings 23-j and 23-k and radiate energy. Part of the energy is incident into the cavity from the openings 23-j and 23-k of the other tubular members 21-j and 21-k adjacent to each other. In this way, coupled vibration is generated between the tubular members 21-j and 21-k adjacent to each other, and energy is transferred. During this coupled vibration, energy is consumed and sound pressure is reduced by friction on the inner wall surface of the cavity and viscous action between gas particles at the openings 23-j and 23-k. This coupled vibration can be regarded as a closed tube mode in which both ends of the tubular member 21 are regarded as a series of tubular members, and the sound pressure is reduced centering on a frequency having a wavelength determined as L1 + L2.
Here, although the number of the tubular members 21 constituting the acoustic tube 2 is five, the number may be any number. In this embodiment, the acoustic tube 2 composed of five tubular members 21 or the acoustic tube 2 composed of one tubular member 21 (that is, the tubular member 21) is used.

(B-2) Configuration of Cabin 105 Next, a configuration of a portion where the acoustic tube 2 is provided in the cabin 105 will be described. Also in this embodiment, the acoustic tube 2 provided in the passenger compartment 105 has a set condition that can suppress the natural vibration mode of the natural frequency in the 160 Hz band as the specific natural frequency. To do. Here, the resonance frequency of the acoustic tube 2 is set to substantially coincide with the natural frequency.
FIG. 15 is a perspective view showing the vehicle 100, and FIG. 16 is a view showing a state in which the passenger compartment 105 is viewed from the obliquely rear side with the front seat 140A as a center. The acoustic tube 2 is provided at each position shown in FIGS. 15 and 16, and the position where the acoustic tube 2 is provided is the same as in the first embodiment, and is the roof, the center pillar, the front pillar, the front seat, and the front door. . The acoustic tube 2 provided in each of these parts is provided such that the hollow region 25 is connected to the vehicle interior 105 through the opening 23. Further, the effects exhibited when the resonator is provided at each of these parts are the same as those described in the first embodiment.
Next, the structure of each part in which the acoustic tube 2 is provided will be described.

(B-2-1) Roof 110a
First, the configuration of the roof 110a will be described. 17 is a cross-sectional view when the roof 110a is cut in the same direction as the arrow VIII-VIII in FIG.
As shown in FIGS. 15 and 17, the acoustic tube 2 is provided in a portion (ceiling portion) of the roof 110a that is almost directly above the riding area where the front seats 140A and 140B are provided. Each of these acoustic tubes 2 includes five tubular members 21, and the arrangement direction thereof is the front-rear direction of the vehicle 100. Further, since the antinode of the sound pressure to be controlled is located near the side window 153, the opening 23 of each tubular member 21 is formed on the side window 153 in order to increase the effect of reducing the sound pressure at this place. Try to face the direction. In other words, the acoustic tube 2 is provided so as to open toward the wall portion closer to the vehicle width direction among the wall portions constituting the passenger compartment 105.
As shown in FIG. 17, a hole 116 is formed at a position near the opening 23 of the roof inner panel 114a to allow the passenger compartment 105 to communicate with the space on the upper surface of the roof inner panel 114a. Sound from the passenger compartment 105 enters the opening 23 of the acoustic tube 2 through the hole 116. In addition, the acoustic tube 2 located near the back of the assist grip 200 is formed by a single tubular member whose extension direction is provided along the front-rear direction of the vehicle 100, but in the vicinity of the opening 23 of the acoustic tube 2. In addition, a hole 117 is formed so that sound from the passenger compartment 105 enters. With this configuration, the mode of the passenger compartment 105 can be effectively suppressed for the same reason as in the first embodiment.

(B-2-2) Center pillar 120a and front pillar 130a
Next, the configuration of the center pillar 120a and the front pillar 130a will be described.
18 is a cross-sectional view of the center pillar 120a as viewed from the direction DD in FIG. The center pillar 120a has a center pillar inner panel 122a attached to a center pillar outer panel 121 (not shown). A surface material 123 is provided on the side of the passenger compartment 105 of the center pillar inner panel 122a. In the center pillar inner panel 122a, a space S is formed between the surface pillar 123 and the surface pillar inner panel 122a. A recess 125 is formed in a part of the center pillar inner panel 122a so as to protrude toward the vehicle outer side in the vehicle width direction so that the space S is formed. A hole 126 is formed in the upper end surface of the recess 125 facing upward. The acoustic tube 2 is provided so that the vicinity of the opening 23 of the tubular member 21 is fitted into the hole 126. Sound from the passenger compartment 105 enters the opening 23 via the surface material 123 and the space S. Since the acoustic tube 2 resonates according to this sound, the sound pressure can be reduced at the antinode of the sound pressure to be controlled, and the mode of the passenger compartment 105 can be suppressed.
As shown in FIG. 16, the acoustic tube 2 is also provided on the front pillar 130a. However, the configuration related to the attachment can be the same as that of the center pillar 120a, and the mode can be suppressed by the same operation. Detailed description thereof will be omitted.

(B-2-3) Front seat 140
Next, the configuration of the front seat 140 will be described.
As shown in FIG. 16, the acoustic tube 2 is provided on each of the seat back 142 and the headrest 141 of the front seat 140. In the seat back 142, two acoustic tubes 2 are provided so as to stand inside the seat back 142 of the front seat 140 so that the opening 23 is positioned on the surface facing upward. The acoustic tube 2 is provided such that the hollow region 25 is connected to the passenger compartment 105 via the opening 23, and sound from the passenger compartment 105 enters the opening 23 via the seat back cover 146. The acoustic tube 2 is also provided in the headrest 141, but is provided inside the headrest 141 in a bent state in order to ensure a sufficient length in the extension direction.

(B-2-4) Front door 150A
Next, the configuration of the front door 150A will be described. Although the acoustic tube 2 is provided on the front door 150A, the acoustic tube 2 is not provided on the rear door 150B here.
FIG. 19 is a diagram illustrating a configuration in which the acoustic tube 2 is provided on the front door 150A, and is an external view of the front door 150A. As shown in FIG. 19, the acoustic tube 2 is provided upright in the door base material 151 of the front door 150 </ b> A so that the opening 23 of each tubular member 21 faces the side window 153. The position of the opening 23 is provided on the relatively upper side of the door base material 151 so that the effect of reducing the sound pressure is enhanced at the position of the antinode of the sound pressure to be controlled, as close to the side window 153 as possible. The door base material 151 is opened at a position near the opening 23 so that sound enters the opening 23. Also in this configuration, it is preferable that processing is performed so that the hole portion of the door base material 151 is not visually observed.

Also in the second embodiment described above, the place that becomes the antinode of the sound pressure of the natural vibration mode of the specific natural frequency in the 160 Hz band is located in the vicinity of the boarding area. Therefore, if the location of the belly of the sound pressure is controlled by the arrangement of the acoustic tube 2, the same effect as that of the first embodiment can be obtained with respect to mode suppression. Also in this embodiment, the antinodes of the sound pressure of the natural vibration mode appearing in the vicinity of the front seat 140 and the side window 153 are controlled, and the acoustic tube 2 has the natural vibration mode of a specific natural frequency of 160 Hz band. It can be said that the sound pressure at least the place closest to the boarding area is reduced among the places where the sound pressure becomes antinode.
Further, when the acoustic tube 2 is composed of a plurality of tubular members 21, coupled vibration can occur, so that the sound pressure can be reduced even at frequencies other than the natural frequency, and the quietness of the passenger compartment 105 can be further enhanced. Can be expected.

[C: Third Embodiment]
Next, a third embodiment of the present invention will be described. In the third embodiment, the resonator provided in the passenger compartment 105 is a Helmholtz resonator, and the basis for selecting the configuration and installation position of the vehicle 100 is the same as that of the first embodiment. In the description of the third embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the corresponding components are denoted by “b” at the end of the reference symbols, and the description thereof is appropriately described. Omitted.

(C-1) Configuration of Resonator First, the resonator provided in the vehicle 100 of this embodiment will be described. In this embodiment, a Helmholtz resonator 3 is used as an example of a resonator. That is, in this embodiment, the resonance body included in the acoustic resonance apparatus is the Helmholtz resonance body 3.
FIG. 20 is a diagram for explaining the configuration of the Helmholtz resonator 3, FIG. 20 (a) is a diagram schematically showing the appearance thereof, and FIG. 20 (b) is an arrow view in FIG. 20 (a). It is sectional drawing which looked at the Helmholtz resonator 3 from EE. The Helmholtz resonator 3 includes a body portion 31 and a tube portion 32. In the Helmholtz resonator 3, a space formed in the body portion 31 and the tube portion 32 is a hollow region, and the hollow region communicates with the opening 33.
The body portion 31 has a gas layer formed therein, and is formed in a cylindrical shape by, for example, FRP (fiber reinforced plastic). The pipe portion 32 is a tubular member having a so-called opening at both ends made of, for example, vinyl chloride, and is inserted into the hole portion of the trunk portion 31 so as to be connected to each other. The Helmholtz resonator 3 is arranged so that the space formed in the body portion 31 and the tube portion 32 is connected to the space that is the target of sound attenuation. As a result, sound enters the opening 33 and the Helmholtz resonator 3 resonates to reduce the sound pressure near the opening 33. More specifically, the Helmholtz resonator 3 forms a spring mass system in which the gas inside the tube portion 32 is a mass component and the gas layer of the body portion 31 is a spring component, and the inner wall of the tube portion 32 and the air The energy of sound is converted into heat energy by friction, reducing the sound pressure near the opening 33 and increasing the particle velocity. The resonance frequency f of the spring mass system of the Helmholtz resonator 3 satisfies the relationship of Expression (5). However, in the formula (5), L _e denotes the effective length of the tube portion 32. As shown in FIG. 20B, the effective length _Le is a length obtained by correcting the length from one end to the other end of the cavity of the pipe portion 32 with the opening end correction value. V is the volume (that is, volume) of the gas layer formed in the body 31, and S is the area of the opening 33.
f = c ₀ / 2π · (S / L _e · V) ^1/2 (5)
In addition, although the number of the pipe parts 32 is 1 here, you may make it provide two or more pipe parts 32, such as two. In addition, the opening 33 of the pipe portion 32 or the vicinity thereof may be blocked with a flow resistance material having air permeability such as glass wool, cloth, gauze, etc. and having flow resistance.

(C-2) Configuration of Cabin 105 Next, the configuration of a portion where the Helmholtz resonator 3 is provided in the vehicle 100 will be described. The positions where the Helmholtz resonator 3 is provided are the same as in the first embodiment, and are the roof 110, the center pillar 120, the front pillar 130, the front seat 140, and the front door 150A. Further, the mounting position can be the same as in the first embodiment, and the Helmholtz resonator 3 provided in each of these parts is provided such that the hollow region thereof is connected to the vehicle interior 105 via the opening 33. Further, the effects exhibited when the resonator is provided at each of these parts are the same as those described in the first embodiment. Here, the roof 110b will be described as an example of the mounting location.
21 is a cross-sectional view of the roof 110b when cut in the same direction as the arrow VIII-VIII in FIG. As shown in FIG. 21, in the roof 110b, a plurality of plate / membrane resonators 1 are arranged on a flat portion of the roof inner panel 114b, and a portion of the roof inner panel 114b inclined to the flat portion (assist The Helmholtz resonator 3 is arranged in a portion having a relatively small mounting area at a position near the back of the grip 200. Thereby, it becomes possible to arrange | position a resonance body effectively with respect to the roof 110b.
Even the configuration of the third embodiment has the same effects as those of the first embodiment.

[D: Summary of Embodiment]
FIG. 22 shows the results of an experiment for examining the noise reduction effect when the resonator is provided in the passenger compartment 105. This graph is a frequency characteristic showing the sound pressure (noise level) at the driver's seat, and the solid line shows the result when there is a resonator, and the broken line shows the result when there is no resonator. This experiment was performed by running the vehicle at 60 km, and in order to obtain a characteristic closer to hearing, a result obtained by adding an auditory characteristic (A characteristic) and using a 1/3 oct bandpass filter is shown.
As shown in FIG. 22, the noise level is reduced in a relatively low frequency band of 125 to 200 Hz. In particular, the reduction amount in the 160 Hz band is 5 dB or more, and a remarkable effect is obtained particularly in reducing the sound pressure in the low frequency range. Also from this result, according to the configuration of the passenger compartment 105 of each of the embodiments described above, the entire passenger compartment 105 is quieter than the case where the low-frequency sound pressure is reduced in a place other than the place where the natural vibration form becomes antinode. In addition to enhancing the performance, the effect on the hearing of the passenger who actually hears the sound can be made remarkable. In addition, since the resonator can be arranged only at an effective position in order to achieve such an effect, it is possible to avoid placing an extra resonator in other locations.

[E: Modification]
The present invention can be implemented in a form different from the above-described embodiment. Further, the following modifications may be combined as appropriate.
(Modification 1)
In each of the above-described embodiments, the plate / membrane resonator 1 is used in the first embodiment, the acoustic tube 2 is used in the second embodiment, and the Helmholtz resonator 3 is used in the third embodiment. These types of resonators may be provided in the passenger compartment 105 in an appropriate combination. Further, the type of the resonator is not limited to these, and any resonator may be used as long as it can reduce the sound pressure by resonating, and the resonator has a hollow region through the opening. It may be provided in the vehicle so as to be connected to 105. Moreover, it is preferable that the resonance body is provided so that an opening is located in the vicinity of the antinode of the sound pressure closest to the boarding area so that the sound pressure is reduced at the antinode. More preferably, the opening may be positioned in the boarding area in order to bring the opening closer to the boarding area.

  Moreover, in each embodiment mentioned above, although the resonance body was provided in all the parts of a roof, a center pillar, a front pillar, a front seat, and a front door, you may provide in only one part among these. For example, in the example of FIG. 5, a resonator may be provided near the front seat 140B that is the driver's seat, and no resonator may be provided near the front seat 140A on the passenger seat side. Further, when the size of the resonator is large, it may be provided across a plurality of parts.

(Modification 2)
In each of the embodiments described above, the sound pressure estimated to be strongly governed by the natural vibration state of the one-dimensional mode in which the sound pressure is distributed in the vehicle width direction appears in the vicinity of the side window 153, so that sound The pressure belly was controlled. On the other hand, regardless of which natural vibration mode to focus on, if the sound pressure is reduced with the belly appearing in the vicinity of the seat, which is the riding area, being controlled, the same effects as those of the above embodiments can be obtained. It is thought that. In other words, even in a passenger compartment where a belly that strongly depends on any natural vibration mode appears, the natural vibration is less likely to be attenuated, and a significant effect can be obtained in terms of mode suppression in a passenger compartment where low-frequency sound is likely to enter. it can.

  As an example, attention may be paid to the natural vibration state of the vehicle 100 in the longitudinal direction of the vehicle 100 in the passenger compartment 105. The length of the vehicle 100 in the front-rear direction is longer than the vehicle width direction. Therefore, for example, in the natural vibration state of the secondary one-dimensional mode in which the sound pressure is distributed in the front-rear direction of the vehicle 100, an antinode of relatively low frequency sound pressure may be located in the passenger compartment 105. More specifically, as the vicinity of the end of the vehicle 100 with respect to the front-rear direction, the natural vibration state of the instrument panel 210 (shown in FIG. 5), the center pillar 120, the rear pillar 180, and the rear package tray 220 of the passenger compartment 105 Sound pressure belly may appear. Therefore, a resonator may be installed in the vicinity of the end of the vehicle interior 105 in the front-rear direction of the vehicle 100 so as to suppress the mode with this as a control target. Further, in the case of this natural vibration mode in the one-dimensional mode, since the antinodes of the sound pressure of the secondary natural vibration mode are also located near the center of the passenger compartment 105 with respect to the longitudinal direction of the vehicle 100, the front seat 140A, By providing a resonance body in 140B, it can be expected that the mode is suppressed with the antinode of the sound pressure located at this place as a control target.

  In each of the above-described embodiments, the resonator is provided so as to reduce the sound pressure at the place of the antinode of the sound pressure closest to the boarding area, but the antinode of the other sound pressure is to be controlled. It does not prevent. For example, when attention is paid to things other than the primary natural vibration state in the vehicle width direction, the sound pressure antinode is located at a position very close to the boarding area, but it is the sound pressure antinode closest to the boarding area. It may not be. In addition, regarding the antinodes of the sound pressure to be controlled, the modes (one-dimensional mode, two-dimensional mode, three-dimensional mode) of natural vibrations that cause the appearance of the antinodes of the sound pressure, and the order (the above-described primary, No matter what kind of mode the secondary etc. is, the resonance pressure is determined by the antinode of the sound pressure that is determined according to the position of the boarding area and that appears in the vicinity of the boarding area. If it arrange | positions, while the result of FIG.6, 7 can also understand, while reducing the sound pressure of the comparatively low frequency of the compartment 105, the effect which the passenger | crew of the compartment 105 hears at a place where sound is heard can be heightened. It is considered possible.

(Modification 3)
In 3rd Embodiment mentioned above, the pipe part 32 of the Helmholtz resonator 3 may be deform | transformed into the structure by which the length can be changed freely. FIG. 23 is a view showing an example of the configuration of the tube portion 32a of this aspect, FIG. 23 (a) is a cross-sectional view of the tube portion 32a in the extending direction, and FIG. 23 (b) shows the tube portion 32a in (a). It is the figure seen from the opening part 323 side.
As shown in FIG. 23, the pipe portion 32a includes an inner pipe 322 and an outer pipe 321. The inner tube 322 is a tubular member, and a groove constituting a male screw is provided on the outer peripheral surface thereof. The inner pipe 322 is fixed in a state in which the inner pipe 322 is prevented from rotating around the body portion 31. The outer tube 321 is a tubular member having an inner diameter larger than that of the inner tube 322, and a groove constituting a female screw is provided on the inner peripheral surface thereof. The tube portion 32a is configured by screwing the inner tube 322 into the outer tube 321, and the total length of the tube portion 32a, that is, the length L of the tube portion 32a is the degree of screwing of the outer tube 321 with respect to the inner tube 322. It depends on. As shown in FIG. 23 (b), the outer periphery of the outer tube 321 is a hexagonal column, and the user can freely change the length L of the tube portion 32a by adjusting the screwing condition using a tool such as a spanner. Can do. As described above, since the resonance frequency of the Helmholtz resonator 3 is determined by the length of the tube portion 32a, the resonance frequency can be adjusted as necessary.
In order to change the length of the tube portion 32a, the inner tube 322 and the outer tube 321 constitute a screw member. However, the inner tube 322 and the outer tube 321 may be constituted by three or more screw members, or may have a bellows shape. A tube may be used, and various configurations that can expand and contract the tube portion 32a can be used. Moreover, although the outer periphery of the outer tube | pipe 321 may not be a hexagonal column shape, it is preferable that it is processed so that a user can adjust the length of the pipe part 32a easily.
According to this configuration, it is relatively easy to adjust the frequency that increases the amount of reduction in sound pressure even if the frequency at which quietness is desired to increase is different depending on the type of vehicle 100 and the material and configuration of the passenger compartment 105. Can be done.

(Modification 4)
Instead of the acoustic tube 2, the following lattice member 4 can also be used.
FIG. 24 is a view for explaining a resonator according to this modification. FIG. 24A is an exploded perspective view showing the structure around the lattice member 4, and FIG. 24B is a view showing the state around the lattice member 4 in the direction of arrow F in FIG. It is.
As shown in FIG. 24A, the lattice member 4 includes a partition 4A extending in one direction and six partitions 4B arranged so as to intersect with the extending direction of the partition 4A. The grid member 4 provided in the vehicle is provided on the upper surface of the roof inner panel 114 such that the partition portion 4A extends in the front-rear direction of the vehicle 100, for example, and the partition portion 4B extends in the vehicle width direction orthogonal thereto. Thereby, the lower end surface side of the lattice member 4 is covered and closed by the roof inner panel 114. On the other hand, the upper end surface side of the lattice member 4 is closed by a part of the chassis that becomes the base of the vehicle 100. The part of the chassis is, for example, a roof outer panel 160 to which the roof inner panel 114 is attached.

  With this configuration, a partition region 4B adjacent to each other forms a hollow region having an extending direction that opens in the vehicle width direction, and a resonance body having a configuration equivalent to that of the acoustic tube 2 is configured. In addition, the lattice member 4 is good also as a member by which both the upper end surface or the lower end surface, or any one was block | closed. In short, a member that forms a resonator when attached to the ceiling of the vehicle 100 can be used in place of the acoustic tube 2. Further, the configuration of the partition portion 4B may be variously modified according to the desired number of resonators (hollow regions).

(Modification 5)
In the first embodiment described above, the configuration of the plate / membrane resonator 1 includes the rectangular housing 10, the vibration portion 15 that closes the opening of the housing 10, and the gas layer 13 formed in the housing 10. However, the shape of the housing is not limited to a rectangular shape, and may be a circular shape or a polygonal shape. Moreover, it is desirable to provide a concentrated mass for changing the vibration condition with respect to the vibration unit 15 in the central portion of the vibration unit 15 in any shape of the casing.
By the way, as described above, the plate / membrane resonator 1 has a sound absorption mechanism formed of a spring mass system and a bending system. Here, the inventors conducted an experiment of the sound absorption coefficient at the resonance frequency when the surface density of the vibrating portion 15 was changed.

FIG. 25 shows that the vibrating portion 15 (size: 100 mm × 100 mm, thickness: 0.85 mm) is fixed to the casing 10 having a vertical and horizontal size of 100 mm × 100 mm and a thickness of 10 mm. It is the figure which showed the simulation result of the normal incidence sound absorption coefficient of the board and the film | membrane resonator 1 at the time of changing the surface density of a part (a magnitude | size is 20 mm x 20 mm, thickness 0.85mm). The simulation method is based on JIS A 1405-2 (measurement of sound absorption coefficient and impedance by an acoustic tube—part 2: transfer function method), and the sound field of the acoustic chamber in which the plate / membrane resonator 1 is disposed is finite. The sound absorption characteristic was calculated from the transfer function obtained by the element method. Specifically, the surface density of the central part is (1) 399.5 [g / m ² ], (2) 799 [g / m ² ], (3) 1199 [g / m ² ], (4) 1598 [g / m ² ], (5) 2297 [g / m ² ], the surface density of the peripheral member is 799 [g / m ² ], and the average density of the vibration part 15 is (1) 783 [g / m ² ]. m ² ], (2) 799 [g / m ² ], (3) 815 [g / m ² ], (4) 831 [g / m ² ], (5) 863 [g / m ² ] This is a simulation result. Looking at the simulation results, the sound absorption rate is high between 300 and 500 [Hz] and in the vicinity of 700 [Hz].

  The high sound absorption rate near 700 [Hz] is due to resonance of the spring mass system formed by the mass of the vibration part 15 and the spring component of the gas layer 13. In the plate / membrane resonator 1, sound is absorbed with the sound absorption coefficient at the resonance frequency of the spring mass system as a peak, and even if the surface density of the central part is increased, the mass of the entire vibration part 15 does not change greatly. It can be seen that the resonance frequency of the spring mass system does not change greatly. Further, the sound absorption coefficient between 300 and 500 [Hz] is high due to the resonance of the bending system formed by the bending vibration of the vibrating portion 15. In the plate / membrane resonator 1, the sound absorption coefficient at the resonance frequency of the bending system appears as a peak on the low frequency side, and only the resonance frequency of the bending system decreases as the surface density at the center increases. I understand that. In general, the resonance frequency of the bending system is determined by an equation of motion that governs the elastic vibration of the vibration part 15 and is inversely proportional to the density (surface density) of the vibration part 15. Further, the resonance frequency is greatly influenced by the density of antinodes of natural vibration (when the amplitude becomes a maximum value). For this reason, in the simulation described above, the region that becomes the antinode of the 1 × 1 eigenmode is formed at a different surface density in the central portion, so that the resonance frequency of the bending system is changed.

Thus, the simulation results show that when the surface density of the central part is made larger than the surface density of the peripheral part, the peak of the sound absorption coefficient on the low frequency side of the frequency that becomes the peak of sound absorption moves further to the low frequency side. Represents. Therefore, it is shown that a part of the frequency at which the sound absorption is peaked can be further moved to the low sound range side or the high sound range side by changing the surface density of the central portion. In the plate / membrane resonator 1 described above, since the frequency of the peak of the sound to be absorbed can be changed only by changing the surface density of the central portion, the vibrating portion 15 is made of the same material as the plate / membrane resonator 1 as a whole. Compared with the case where the sound is absorbed by changing the weight of the entire plate / membrane resonator 1 by increasing the mass of the entire plate / membrane resonator 1, sound absorption occurs without greatly changing the mass of the entire plate / membrane resonator 1. The frequency can be lowered.
Furthermore, the resonance characteristics may be changed by filling the gas layer 13 of the plate / membrane resonator 1 with a porous sound-absorbing material (for example, foamed resin, felt, cotton wool such as polyester wool). . In this way, the noise characteristics in the passenger compartment change due to changes in the natural vibration mode (changes in the number of people and luggage, changes in shape, etc.) and changes in generated noise (changes in tires, changes in road conditions, etc.). Can also respond.

(Modification 6)
In the first embodiment described above, each plate / membrane resonator 1 has the same shape, but these plates / membrane resonators 1 may have different shapes. Thereby, since the resonance frequency of the plate / membrane resonator 1 varies depending on the dimensions of the casing 10 of the plate / membrane resonator 1, the range of frequencies where the sound pressure is reduced can be expanded. For example, the resonance frequency may be different between the front seat 140A and the front seat 140B. Further, the resonance frequency may be different between the roof 110 and the center pillar 120. In this way, the sound pressure in a wider frequency band can be reduced, and the sound with the optimum frequency according to the location can be attenuated. That is, the resonance bodies may be grouped in one or a plurality of units, and the resonance resonance frequency may be different for each group. Similarly, the resonance frequencies of the acoustic tube 2 and the Helmholtz resonator 3 may be varied.
Moreover, in 2nd Embodiment mentioned above, although one edge part of the tubular member 21 became the opening part 23 and the other edge part became the closing part 22, it was what is called a closed tube, For example, both ends of each tubular member 21 You may comprise with the pipe | tube (what is called an open pipe) by which the part was opened, and you may arrange | position these closed pipes and open pipes in mixture.

(Modification 7)
In each of the above-described embodiments, the resonator is provided in the vehicle 100 that is an automobile, but may be provided in other types of vehicles. For example, a vehicle compartment of a train, a ship, an aircraft, a space station, a gondola or the like may be used. As described above, the vehicle includes, for example, a transport device that moves with a person who is a passenger. In addition to this, vehicles that are not intended for transport of passengers, such as a ferris wheel that is an amusement park playground equipment, are also included in the vehicle of the present invention. Further, the vehicle is not limited to a vehicle room used as a person's room in a vehicle, and may be a vehicle room such as a machine room or a luggage room provided separately. This is because such a passenger compartment is also a space where passengers can get on. In addition, depending on the type of vehicle, a seat may not be provided in the boarding area of the passenger compartment. For example, in a gondola, a bus, a train, etc., there may be many passengers who do not sit on the seat. Even in this case, the boarding area of the rider is determined in advance. Therefore, if the mode is controlled with the sound pressure belly of the place corresponding to the boarding area as the control target, the same effects as those of the above-described embodiments are obtained. Play.
In addition, the roof, center pillar, front pillar, front seat, and front door were configured by a vehicle that is an automobile, but in other vehicles, if there is a member that performs the same function as these, it resonates there. A body may be provided. In addition, these members are not limited to the case where they are attached to the vehicle 100 or the passenger compartment 105, but are not yet integrated with the vehicle 100 and the passenger compartment 105 at the stage before attachment. Can be specified as the acoustic resonance device of the present invention.
In addition, the resonator is not limited to the structure provided in the wall portion surrounding the passenger compartment 105 or the seat in the boarding area, but a place capable of reducing the sound pressure in the place of the antinode of the natural vibration state. If so, the installation position may be anywhere.

(Modification 8)
Moreover, in the structure of the modification 3, adjustment of the length of the pipe part 32a may be automated. In this case, an automatic adjustment mechanism including, for example, a microphone, a frequency analysis device, a controller, and a drive device for adjusting the length of the tube portion 32a is provided. In the automatic adjustment mechanism, sound is picked up by a microphone, and a frequency analysis device analyzes a signal representing the picked-up sound to identify a particularly noisy frequency. The controller calculates the length of the tube portion 32a of the Helmholtz resonator 3 according to the specified frequency, and outputs a drive signal corresponding to the length to a drive device composed of a solenoid or the like. The drive device can adjust the length of the tube portion 32a of the Helmholtz resonator 3 in accordance with the drive signal, and can reduce the sound pressure at a particularly loud frequency. Note that the controller may perform feedback control when driving the tube portion 32a.
Moreover, you may make the dimension of the trunk | drum 31 of the Helmholtz resonator 3 of the above-mentioned 3rd embodiment variable using the structure which concerns on the expansion-contraction of the above-mentioned embodiment. In this case, the volume of the gas layer formed in the body part 31 changes, and the resonance frequency can be made variable. Also, the acoustic tube 2 of the second embodiment may be adjustable in length in the extension direction by the same configuration.

(Modification 9)
In each of the above-described embodiments, a resonance body is arranged with a place to be the antinode of the sound pressure of the natural vibration form having a specific natural frequency as a control target, and the amount of reduction of the sound pressure at the natural frequency is high. However, it may be set to a resonance frequency for attenuating sound having a frequency different from that.
For example, when the vehicle 100 is traveling, the tire becomes an excitation source (that is, a source that applies vibration to the passenger compartment 105), and vibration of a certain frequency (hereinafter referred to as “excitation frequency”) occurs in the vehicle 100. Noise due to the vibration may be generated in the passenger compartment 105. Thus, for example, even if the natural frequency of the passenger compartment 105 is 167 Hz, the frequency at which the sound pressure is highest in the passenger compartment 105 is, for example, 155 Hz, and each sound is within the same frequency band to be controlled. However, each may be slightly different. The frequency band of the same control object here is, for example, a 160 Hz band. Therefore, the position of the resonator may be selected by paying attention to the natural vibration state as in the above embodiments, and the resonance frequency may be determined according to the sound generated by this excitation. That is, when the specific natural frequency and the vibration frequency of the vibration applied to the passenger compartment 105 from the outside are different from each other, the sound pressure can be reduced at the frequency at which the sound pressure is increased by the vibration. Thus, the resonance frequency of the resonator is set. For example, a resonance body is arranged with a sound pressure antinode of a natural vibration state in a 160 Hz band as a control target, and the resonance body is set to resonate at 155 Hz. The excitation frequency and the natural frequency are included in the same predetermined frequency band, but the resonance body may be a predetermined frequency band that can reduce the sound pressure of both frequencies, and the 160 Hz band. It is not limited to.

  In this configuration, when the vehicle 100 is traveling, automatic control may be performed using the configuration of the modified example 8 so that the resonance frequency is matched with the peak frequency of sound generated by vibration. In particular, when the excitation frequency fluctuates (during driving) as in an automobile, the natural frequency is a unique characteristic unique to the sound field, whereas the characteristic on the excitation side (excitation frequency characteristic) is sometimes Since it changes every moment, the characteristic of the natural frequency does not necessarily appear as it is. Therefore, a control device such as a computer automatically controls the resonance frequency to match the excitation frequency, thereby effectively reducing room noise. The excitation frequency may be calculated by the control device from parameters such as speed, engine speed, accelerator opening, and gear position.

(Modification 10)
In addition, without setting the resonance frequency of the resonance body as a natural frequency, the sound pressure of the natural frequency is reduced by the interaction related to the coupled vibration between the space in which the resonance body is installed and the space of the housing of the resonance body. You may make it reduce. This is because, in addition to the resonator itself described in the above embodiments, a space in which the resonator is provided can be regarded as a kind of resonator. This is because coupled vibration is generated from the mutual relationship between these resonators, energy is transferred between the resonator and the passenger compartment, and an effect of reducing sound pressure in another frequency band may be obtained.

(Modification 11)
In the acoustic tube 2, the sound energy is consumed by friction between the gas molecules and the inner wall and viscous resistance. Therefore, the consumption of acoustic energy increases as the particle velocity of sound waves increases. Therefore, if the resonator is provided at a position where the particle velocity is high, the acoustic tube 2 can more effectively reduce the sound pressure. For example, the location where the particle velocity is high may be specified by measuring the particle velocity when measuring the antinodes of the sound pressure distribution.

(Modification 12)
In the above-described embodiment, the resonance body is provided to reduce the sound pressure at the place where the sound pressure of the natural vibration state becomes antinode, but the motion speed (that is, the particle speed) of the medium particles at the place is increased. You may make it provide the resonator for making it. More specifically, the movement speed of the medium particles is a speed at which the medium particles vibrate.
In a place where the sound pressure of the natural vibration state is located in the passenger compartment 105, the sound pressure is maximized, whereas the particle velocity is minimized. Producing the action of increasing the particle velocity at a place where the particle velocity is small also causes a change in the mode of the natural vibration state, which can contribute to enhancing the quietness of the entire room space. . Even in this configuration, the same effect as that of the embodiment can be obtained by causing an action due to resonance to the medium where the sound pressure is originally increased due to the appearance of the antinode of the natural vibration state. .

As the resonator of this modification, for example, an acoustic tube can be used. In the hollow region of the acoustic tube, a standing wave exists so as to meet a boundary condition in which the particle velocity at the closed end becomes zero. For example, at the primary resonance frequency (lowest resonance frequency), the opening portion The particle velocity at is maximized. Therefore, if the position of the opening is arranged in the vicinity of the anti-sound pressure in the natural vibration state or in the vicinity thereof, the particle velocity at that place can be increased. In addition, when increasing the particle velocity using the acoustic tube 2, it is desirable not to use the flow resistance material 24. This is because a larger particle velocity can be generated by resonance when the flow resistance member 24 is not provided. Further, even when the plate / membrane resonator 1 or the Helmholtz resonator 3 is used, the particle velocity is increased at the position of the vibrating portion 15 of the plate / membrane resonator 1 or the opening 33 of the Helmholtz resonator 3. be able to.
Note that the above-described configuration relating to the increase in particle velocity is only an example, and a resonator that can increase the particle velocity by resonating can be used. In short, the arrangement mode of the resonators may be determined so as to produce an action of increasing the particle velocity at a place where the antinodes of the sound pressure in the natural vibration mode.

(Modification 13)
For example, there is a case where there is a sound pressure bellows in the vicinity of the rear seat 190, which is another riding area, without increasing the quietness in the front seat 140, and it is particularly desired to increase the quietness in the riding area. It is done. In this case, for example, a resonator is provided to control the sound pressure antinode of the natural vibration state located near the ceiling portion of the roof 110 directly above the rear seat 190, the rear door 150B, the rear pillar 180, etc. A resonance device may be configured. In other words, it is not limited to the arrangement for enhancing the quietness of the driver's seat and the passenger's seat, and as long as it is a riding area provided in the passenger compartment, the place of the sound pressure belly of the natural vibration state corresponding to the position of which riding area May be controlled.
In addition, the wall portion on which the resonator is provided is not limited to the portion that partitions the vehicle compartment from the outside of the vehicle, but is a wall portion that faces only the vehicle interior space, such as a door or a column provided in the vehicle interior. May be.
In each of the embodiments described above, attention has been paid to the antinodes of the sound pressure in the natural vibration mode of the natural frequency in the 160 Hz band, but another natural frequency may be noted.
Further, the region where the sound pressure is reduced by the resonance of the resonator and the region where the particle velocity is increased are determined by the position of the opening. Therefore, the other part of the resonator is not limited to the passenger compartment, and may be provided anywhere in the vehicle.

DESCRIPTION OF SYMBOLS 1 ... Plate | seat / membrane resonator, 100 ... Vehicle, 105 ... Cab, 110, 110a, 110b ... Roof, 114, 114a, 114b ... Roof inner panel, 120, 120a ... Center pillar, 130, 130a ... Front pillar, 140 140A, 140B ... front seat, 141 ... headrest, 142 ... seat back, 150 ... door, 150A ... front door, 150B ... rear door, 180 ... rear pillar, 190 ... rear seat, 2 ... acoustic tube, 200 ... assist grip, 3 ... Helmholtz resonator, 4 ... lattice member.

Claims (10)

A resonator having an opening and a hollow region communicating with the opening, the resonator including a resonator provided in a vehicle such that the hollow region is connected to a passenger compartment through the opening;
Among the places that become the antinodes of the sound pressure of the natural vibration state of the specific natural frequency in the passenger compartment, the resonator has the sound pressure of the natural frequency at a place determined according to the position of the boarding region in the passenger compartment. An acoustic resonance apparatus characterized by being reduced by resonance. 2. The acoustic resonance according to claim 1, wherein the resonance body reduces a sound pressure at least at a place closest to the boarding area among places where the sound pressure of the natural vibration state of the natural frequency becomes antinode. apparatus. A resonator having an opening and a hollow region communicating with the opening, the resonator including a resonator provided in a vehicle such that the hollow region is connected to a passenger compartment through the opening;
Of the places that become the antinodes of the sound pressure of the natural vibration state of the specific natural frequency in the passenger compartment, the motion speed of the medium particles of the natural frequency in the place determined according to the position of the boarding region in the passenger compartment, An acoustic resonance apparatus, wherein the resonance body is increased by resonating. The natural frequency and the frequency of vibration given to the passenger compartment from the outside are different from each other,
The resonance frequency of the resonator is set so as to reduce the sound pressure at a frequency determined according to the position of the boarding region and excited by the vibration by the resonance. The acoustic resonance apparatus according to any one of claims 1 to 3, wherein 5. The acoustic resonance apparatus according to claim 1, wherein the natural vibration mode of the natural frequency is a primary natural vibration mode in which sound pressure is distributed in a vehicle width direction of the vehicle. The acoustic resonance apparatus according to any one of claims 1 to 4, wherein the natural vibration mode of the natural frequency is a secondary natural vibration mode in which sound pressure is distributed in the front-rear direction of the vehicle. In the boarding area, there are seats for passengers,
The acoustic resonance apparatus according to claim 1, wherein the resonator is provided in the seat. The acoustic resonance apparatus according to any one of claims 1 to 6, wherein the resonance body is provided on a ceiling facing the passenger compartment. The acoustic resonance apparatus according to claim 1, wherein the resonance body is provided on a support column that supports a roof of the vehicle. The acoustic resonance apparatus according to claim 1, wherein the resonance body is provided on a door facing the vehicle interior.

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