JPH0937371A - Speaker device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce sound waves leaked from the inside of doors and to install a speaker suitable for reproducing a low sound level by arranging a structure material having a sound absorption property inside a door and supporting drawer parts. SOLUTION: A speaker body 5 is supported by a frame in a state opening the rear face of a diaphragm. Space closed by an outdoor wall formed 2 on the outdoor side of a vehicle and an indoor wall 3 arranged on the indoor side of the vehicle is formed and the body 5 is fixed on the indoor wall 3. When the space is used as a speaker cabinet enclosure, the space becomes oscillation space for sound waves radiated from the back of the body 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speaker device which is mounted on a door or a rear shelf of an automobile or the like and reproduces audio.

[0002]

2. Description of the Related Art FIG.
FIG. 2 is an exploded cross-sectional view showing a conventional vehicle speaker device disclosed in Japanese Patent Publication No. JP-A-2003-242, in which 1 is an automobile door, 2 is a door outer panel (outdoor wall), 3 is a door inner panel (indoor wall), 4 Is glass, 5 is a speaker, 6 is a waterproof sheet, 7 is a newly added sound absorbing material such as sponge, 8 is a trim, and 9 is an opening used for assembly and maintenance work.

In such a structure, when the speaker 5 is driven, sound waves are radiated both in front of the speaker 5 and behind the speaker 5. The sound wave emitted to the back has a phase opposite to that of the sound wave emitted to the front. The sound wave radiated to the back propagates inside the automobile door 1 and propagates from the opening 9 to the outside. Sound waves emitted to the outside are slightly shielded by the waterproof sheet 6 and absorbed by the sound absorbing material 7. When the sound wave behind the speaker 5 is absorbed, the sound wave of the opposite phase that interferes with the sound wave radiated in front of the speaker 5 is reduced, and the sound pressure is prevented from lowering due to the interference. As described above, the conventional acoustic device is configured to act on the sound waves that have come out of the door. Therefore, not only is airtight so that sound waves do not leak from the gap between the opening 9 and the sound absorbing material 7, but also other small openings of the door are closed with the sound absorbing material.
I had to close the whole thing. Further, the soft sound absorbing material 7 such as sponge has a problem that it loses elasticity due to aging and has a gap.

Further, in such an acoustic device, the sound absorbing material 7
Since it is attached to the outside of the door inner panel 3, it acts on the sound waves that have passed through the opening 9 and the waterproof sheet 6, but it is difficult to act on the sound pressure generated inside the automobile door 1. . Further, sponge generally has a large sound absorption coefficient in a band of several KHz, but the sound absorption coefficient tends to be small at several hundred Hz or less where the sound pressure inside the door increases. Therefore, hundreds of H
There was a problem that the thickness of the sponge had to be made considerably thick in order to obtain sufficient sound absorption at z or less.

FIG. 30 shows a usage state of a sound absorbing material used inside a speaker box for home or business use. The figure is an enlarged view of a part of the cross-sectional view of the inner wall of the speaker box. In the figure, 10 is a set screw, 11
Is a stopper, 12 is a housing which is a speaker box, and 13 is a soft porous material such as glass wool. In this example, an air layer is provided between the housing 12 and the soft porous material 13 while being bent and fixed to the stop 11 by the set screw 10. Since the soft porous material 13 has a non-uniform shape, it has a drawback that it is difficult to handle. Soft porous material 13
29 is attached to the inner wall of an automobile door as shown in FIG. 29, the inner work is performed from the opening 9, so it is difficult to perform fine work, it is difficult to attach the corrugated shape, and the dimensional accuracy is insufficient and the sound absorbing effect is unstable. There was a problem that it was easy to become. Furthermore, when a soft sound absorbing material such as sponge, urethane foam, or glass wool is attached to the inside of an automobile door, raindrops that have leaked into the automobile door will impregnate the sound absorbing material and stop, corroding the metal inside the door. There was a flaw.

[0006]

As described above, since the conventional vehicle speaker device is constructed so that the soft sound absorbing material is attached to the outside of the opening of the door inner panel, the sound generated inside the door is reduced. It had a drawback that it was hard to act on pressure. Further, since it is necessary to mount the soft sound absorbing material in a wavy shape so as not to reduce the sound absorption coefficient, it is difficult to mount it inside the housing having movable parts such as inside the door.

The present invention has been made in order to solve the above-mentioned problems, and a structural material having a sound absorbing property is installed inside the door to support the door parts and to prevent sound waves leaking from the inside of the door. It is an object of the present invention to obtain a speaker device having a structure suitable for low-frequency sound reproduction.

[0008]

A vehicle speaker device according to the present invention includes a speaker main body supported by a frame with a back surface of a diaphragm open, an outdoor wall provided outside the vehicle, and a vehicle. Forms a space that is substantially sealed with the indoor wall provided on the indoor side, fixes the speaker body to the indoor wall, and uses the space as a vibration space for sound waves emitted from the back surface of the speaker body. An enclosure is provided in the enclosure, and includes a hard porous sound absorbing plate that absorbs sound waves of a predetermined frequency among sound waves from the back surface of the speaker main body and has a predetermined structural function in the enclosure.

Further, in the above structure, the hard porous sound absorbing plate has a function as a waterproof wall which prevents water droplets from adhering to the back surface of the speaker body.

Further, the hard porous sound absorbing plate has a function as a reinforcing material for increasing the strength of the enclosure.

Further, the hard porous sound absorbing plate has a function of a supporting member for supporting the window glass opening / closing member which can be housed in the enclosure.

Further, the hard porous sound absorbing plate has a function as an opening / closing door that closes the working hole in the enclosure provided on the indoor wall.

In the vehicle speaker device according to the present invention, the speaker main body is supported by the frame with the back surface of the diaphragm open, the outdoor wall provided outside the vehicle and the indoor side of the vehicle. An enclosure that forms a substantially sealed space with the provided indoor wall, fixes the speaker body to the indoor wall, and uses the space as a vibration space for sound waves radiated from the back surface of the speaker body,
The enclosure is provided with an opening for working provided on an indoor wall of the enclosure, and at the same time, absorbs a sound wave of a predetermined frequency among the sound waves from the back surface of the speaker body, and is provided so as to face the indoor surface of the indoor wall. It has a hard porous sound absorbing block that supports the interior material.

Further, in the above structure, a plurality of hard porous sound absorbing blocks are provided, and each of them has a different sound wave frequency.

Further, in the vehicle speaker device according to the present invention, the speaker main body is supported by the frame with the back surface of the diaphragm open, the outdoor wall provided on the outdoor side of the vehicle and the indoor side of the vehicle. A space formed with the provided indoor wall,
The speaker body is provided with a speaker box that is made of a hard porous sound absorbing plate that absorbs sound waves of a predetermined frequency among the sound waves emitted from the back surface of the speaker body, and the speaker body substantially seals the back surface of the speaker body. The speaker box is fixed to the interior wall in the space so that the speaker box faces the room.

In the vehicle speaker device according to the present invention, the speaker main body is supported by the frame with the back surface of the diaphragm open, the outdoor wall provided outside the vehicle and the indoor side of the vehicle. While forming a substantially sealed space with the provided interior wall, the speaker body is fixed to the interior wall, and an enclosure is provided that uses the space as a vibration space for sound waves radiated from the back surface of the speaker body, A Helmholtz resonance structure is formed in the structure provided in this enclosure.

In the above structure, a plurality of Helmholtz resonance structures are provided, and each of them has a different sound wave frequency.

Further, in the above structure, the hard porous sound absorbing plate or block has an air layer formed by these and other members.

The air layer is composed of a plurality of layers having different thicknesses.

The hard porous plate or block is
Used with Helmholtz resonant structures formed in other structures.

[0021]

The hard porous sound absorbing plate or block according to the present invention fulfills a predetermined function as a structure inside an automobile door and absorbs sound waves generated inside the door to reduce sound pressure. The function as a structure is to prevent water droplets from adhering to the speaker as a waterproof cover, to increase the strength of the inner wall of the door and the interior material, and to act as a door for opening and closing working holes inside the enclosure.

Further, the air layer in the present invention absorbs sound waves inside the door at a band near resonance frequencies of primary, secondary, tertiary, etc. generated by resonance inside the door for automobiles, and lowers sound pressure. .

[0023]

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a front door for an automobile as seen from a vertical plane passing through the center of the speaker. In the figure, 1 is an automobile door, 2 is a door outer panel (outdoor wall), 3
Is a door inner panel (indoor wall), 4 is a window glass, 5
Is a speaker, 6 is a waterproof sheet, 8 is a trim, 9 is an opening provided in the door inner panel 3, 20 is a waterproof cover,
Reference numeral 21 is a clip for fixing the trim 8 to the small hole of the door inner panel 3, and 22 is a speaker grill. A waterproof sheet 6 is attached to the inner door panel 3, and the waterproof bar 6 is screwed so that the waterproof sheet 6 is sandwiched from the outside.

FIG. 28 is a cross-sectional view of an electrodynamic speaker which is an example of a speaker. It shows the magnetic flux of the magnetic circuit composed of the plate 115, the magnet 117 and the pole piece 118 and the force generated by the current flowing through the voice coil 116. The diaphragm 111 vibrates, and a sound wave is generated. The diaphragm 111 and the dust cap 119 include a frame 112, an edge 113,
It is supported by the damper 114.

The waterproof cover 20 is formed in a shape that heats a hard porous sound absorbing material (hereinafter referred to as sound absorbing plastic) to cover the rear surface of the speaker 5 from above. Raindrops that have entered the interior of the door through the openings through which the glass 4 enters and exits hit the waterproof cover 20 and are not repelled to wet the diaphragm of the speaker 5.

Sound-absorbing plastic is a hard, porous sound-absorbing material, and is described in the document "Mitsubishi Electric Technical Report VOL.65, N0.4, 1".
The basic structure, manufacturing method, etc. are described on pages 17 to 21 of "991". Figure 24 shows the basic structure of sound-absorbing plastic.
Shown in Sound absorbing plastic has a diameter of 0.5 mm to 2.0 m
While welding spherical plastic particles of about m,
A high sound absorption coefficient is obtained by changing the degree of welding in the thickness direction.

FIG. 25 shows a comparative example of the sound absorbing characteristics of the sound absorbing plastic. The characteristic diagram is a disk-shaped test piece (diameter 100
mm), and is the normal incident sound absorption coefficient measured by the JIS A1405 in-tube method. In the figure, the symbol Δ indicates the sound absorption coefficient of a conventionally used urethane material having a thickness of 10 mm. The mark is the sound absorption coefficient of a sound absorbing plastic having a thickness of 10 mm. Compared with the same thickness, the sound absorbing plastic has a slightly higher sound absorbing coefficient. In the figure, the circles indicate the sound absorption coefficient when the thickness of the sound absorbing plastic is 5 mm and the air layer is 5 mm on the back surface of the sound absorbing material. By providing an air layer on the back surface, a sound absorption coefficient of about 2 times at 1 KHz can be obtained as compared with a urethane material having a thickness of 10 mm.

The sound absorbing operation will be described below. When the diaphragm of the speaker 5 vibrates, the air becomes sparse and dense, and the pressure difference propagates, so that sound waves are radiated in front of the speaker 5. The sound waves radiated forward pass through the speaker grill 22 attached to the trim 8 and propagate to the outside.
On the other hand, at the same time when sound waves are emitted in front of the speaker 5,
An opposite phase compression wave is generated inside the automobile door 1.
The sound wave of the opposite phase generated from the back side of the diaphragm of the speaker 5 is
Propagate in the air inside the door. The sound waves reach the waterproof cover 20 made of sound absorbing plastic, and a part of the sound waves are absorbed. The remaining sound waves that have been absorbed are reflected by the waterproof cover 20.

Assuming that the normal incident sound absorption coefficient of the sound absorbing plastic is α, the ratio between the sound pressure of the sound wave incident on the waterproof cover 20 and the sound pressure of the reflected sound wave, that is, the sound pressure reflection coefficient R is | R | = √ (11-α) For example, when the sound absorption coefficient of the sound absorbing plastic is 60%, the sound pressure reflection coefficient is calculated as R = 0.63. When the sound pressure of the incident wave is 1.0, the sound pressure of the reflected wave is 0.63. In this case, the sound pressure of the reflected wave is reduced by 4 dB in the sound absorbing plastic waterproof cover 20 as compared with the completely reflective waterproof cover. Therefore, the sound pressure of the opposite phase generated inside the door decreases inside the door before it goes out through the opening 9. Therefore, it is possible to prevent the sound pressure of the low frequency sound from being lowered without interfering with the sound wave radiated in front of the speaker.

Further, the sound pressure generated inside the automobile door may excite a window regulator, a connector, etc. mounted inside the door to cause a strange noise such as so-called chattering. Further, when the door inner panel 3 is thin, the inner panel 3 itself may be excited and the vibration may be transmitted to the trim 8 or a switch mounted on the trim 8 to cause abnormal noise. According to the present embodiment, the sound pressure itself generated inside the door is reduced, so that the vibrations of the mounted components inside the door and the door inner panel 3 are reduced, and the generation of chattering noise can be prevented. Further, since the waterproof cover 20 is made of sound absorbing plastic itself, there is no need to newly provide a structure, and there is an advantage that it fulfills both functions of sound absorbing and supporting.

Embodiment 2 FIG. FIG. 2 shows a sectional view of a waterproof cover according to a second embodiment of the present invention. In the figure, 24 is a waterproof cover, 25 is a sound insulating resin plate such as polypropylene,
Reference numeral 26 is a sound absorbing plastic plate, and 27 is an air layer. In this embodiment, a sound absorbing plastic plate 26 is used on the speaker side of the waterproof cover 24 to form a shape close to the speaker shape.
A sound-insulating resin plate 25 is formed on the opposite side and integrally bonded,
An air layer 27 is formed inside the waterproof cover 24. The sound wave of the opposite phase generated from the back side of the diaphragm of the speaker 5 propagates in the air inside the door, reaches the waterproof cover 24, and is absorbed by the sound absorbing plastic plate 26. By providing the air layer 27 behind the sound absorbing plastic plate 26, the sound absorbing coefficient tends to increase. In the example of FIG. 25, the sound absorbing plastic B (mark) has no air layer and has a sound absorbing coefficient of about 20% at 1 KHz.
5 for mark, sound absorbing plastic layer 5 mm, air layer 5 mm)
There is an air layer of mm, and the sound absorption coefficient is about 30% at 1 KHz, which is about 1.5 times. In this example,
More sound waves will be absorbed, and the sound pressure inside the door will drop significantly. Further, since the inner wall of the waterproof cover 24 is composed of the sound absorbing plastic plate 26, there is no need to newly provide a structure, and there is an advantage that it functions as both sound absorbing and supporting.

Embodiment 3. FIG. 3 shows a sectional view of a waterproof cover according to a third embodiment of the present invention. In the figure, 28, 2
9 is a sound insulating resin plate, 30 and 31 are sound absorbing plastic plates, 32 is a sound insulating resin plate 28 and sound absorbing plastic plate 30
The thick air layer 33 is a thin air layer formed by the sound insulating resin plate 29 and the sound absorbing plastic plate 31.
In this embodiment, two types of air layers having different thicknesses are provided,
It is configured to adjust the frequency of sound absorption.

FIG. 27 shows changes in the sound absorption coefficient when the thickness of the air layer provided behind the sound absorbing plastic plate having the same thickness is changed. In the figure, the curve A shown by the solid line shows the case where the thickness of the air layer is small, the broken line B shows the case where the thickness of the air layer is medium, and the dashed line C shows the case where the thickness is large. As the air layer becomes thicker, the frequency at which the sound absorption coefficient becomes maximum decreases, and the sound absorption coefficient in the low frequency band tends to increase. By increasing the thickness of the air layer, the frequency can be adjusted to a frequency band of about 1/3 or less. For example, the front and back length is l
In the case of an automobile door with m, height 0.6 m, and depth 0.2 m, if the sound velocity is 340 m / sec, the lowest resonance frequency is about 170 Hz from the length before and after the door, but the next lowest frequency is 283.3Hz from the height of the door, and above that is 3
40 Hz or the like. In this case 283.3Hz and 340
Since the two frequencies of Hz differ by about 1.2 times, one type of sound absorbing plastic plate is used, and by changing the air layer as shown in Fig. 27, the frequency at which the sound absorbing rate becomes maximum can be adjusted. is there. Providing multiple air layers with different thicknesses,
By adjusting the frequency at which the sound absorption coefficient is maximized, it is possible to absorb sound at the resonance frequency at which the sound pressure inside the door becomes large, and there is an advantage that the sound absorption effect can be enhanced.

Embodiment 4 FIG. 4 is a sectional view of a waterproof cover according to a fourth embodiment of the present invention. In the figure, 34 is a waterproof cover formed by molding a resin material such as polypropylene or ABS, and 35 is a Helmholtz resonator similarly formed by a resin material such as polypropylene or ABS. The waterproof cover 34 covers the back of the speaker 5 from above, and prevents raindrops and the like that have entered the inside of the door from wetting the diaphragm of the speaker 5. The Helmholtz type resonator 35 is composed of a small cavity and a thin tube. The air in the tube resonates by acting as a compression and expansion spring for the mass and air in the cavity. The resonance frequency is represented by the following equation (1).

[0035]

[Equation 1]

FIG. 26 shows examples of bottle types and resonance frequencies. When such a resonator is attached to the waterproof cover 34 inside the automobile door 1, the input impedance to the sound wave is small at a frequency near the resonance frequency, and the sound wave is absorbed in the resonator. Therefore, the sound pressure inside the door is reduced.

Many doors of passenger cars are long in the front-rear direction, and resonance occurs in the front-rear direction at the lowest frequency. For example, when the longitudinal length is lm and the sound velocity is 340 m / sec, the resonance frequency is 170 Hz. The tube of the Helmholtz resonator has a radius d = 0.85 cm, a cross-sectional area S = 2.27 cm ² ,
A semicircular shape having a length T = 3.9 cm and a cavity volume of V ₀ =
Assuming that the volume is 500 ml, the resonance frequency is 16 from the equation (1).
It becomes 9.5 Hz, and a Helmholtz resonator that absorbs the lowest frequency can be configured. A reaction force generated when the diaphragm of the speaker 5 vibrates and a sound pressure generated by the vibration of the diaphragm are applied to the waterproof cover 34. The pressure may cause the resonator to vibrate and produce sound. Polypropylene or A
The BS has a high rigidity, and the resonator constituted by these has the advantage that the generated vibration is quickly attenuated and unnecessary sound is not generated. In the embodiment shown in FIG. 4, the Helmholtz resonator 35 is made of a sound insulating resin plate such as polypropylene.
By attaching the sound absorbing plastic material shown in the above-mentioned embodiment to the outer surface of the resonator 35 and the surface of the waterproof cover 34 so as to have sound absorbing property, a waterproof cover is obtained in which both the effect of the resonator and the sound absorbing plastic are obtained at the same time. it can.

Embodiment 5. FIG. 5 is a cross-sectional view of a front door for an automobile according to a fifth embodiment of the present invention viewed from a vertical plane passing through the center of the speaker. In the figure, 36 is a conventional waterproof cover made of a resin material such as polypropylene,
The raindrops that have penetrated into the interior of the automobile door are prevented from being applied to the diaphragm of the speaker 5. Reference numeral 37 is a sound-absorbing plate formed by corrugating sound-absorbing plastic. The sound absorbing plate 37 is bonded to the periphery of the speaker mounting portion of the door inner panel 3 and the inside of the door outer panel 2. Sound waves radiated from the diaphragm of the speaker 5 into the interior of the automobile door are absorbed by the sound absorbing plate 3.
Since sound is absorbed at 7 and the sound pressure is reduced, the sound pressure is prevented from lowering due to interference. Since the sound absorbing plate 37 is formed in a corrugated shape and partially has an air layer, the sound absorbing plate 37 has a higher sound absorbing coefficient than that of a single plate. As the vehicle body becomes lighter, the door inner panel 3 tends to be thinner and lighter. Therefore, the speaker 5
The rigidity around the mounting part is insufficient. In this embodiment, the sound absorbing plate 37 reinforces the door inner panel 3 and the door outer panel 2. Therefore, the diaphragm of the speaker 5 has an advantage that it vibrates following the speaker input signal even when it receives an air load. Also, since it contributes to strengthening the door panel, it is less likely to be dented by an external force, which helps improve safety.

Embodiment 6. FIG. 6 is a perspective view of the interior of an automobile door according to a sixth embodiment of the present invention, showing a window glass lifting mechanism. In the figure, 38 is a window glass,
Reference numeral 39 is a guide for guiding the lifting and lowering of the glass 38, and 43 is a cable type wind regulator which serves as power for lifting and lowering. The guide 39 includes a guide rubber 40 that softly supports and guides the glass 38, and a sound absorbing plastic plate 41 that supports the guide rubber 40. The sound absorbing plastic plate 41 covers the outer periphery of the guide rubber 40 and absorbs sound waves emitted from the speaker to the inside of the door. Reference numeral 42 is a sound absorbing plastic plate attached to the lower end of the glass 38 and similarly absorbs sound waves inside the door.

FIG. 7 is a sectional view when the glass 38 is raised.
Shown in In FIG. 7, 41 is a sound absorbing plastic plate, 4
4 is an inside seal made of synthetic rubber that fills the gap between the glass 38 and the trim 8, 45 is an outside seal, and 46 is an outside molding, which fills the gap between the glass 38 and the door outer panel 2. When the glass 38 rises, the sound-absorbing plastic plate 41 enters between the inside seal 44 and the outside seal 45 to fix the glass 38 and close the opening through which the glass 38 comes in and out, thereby enhancing the airtightness inside the door. is there. In this embodiment, since the guide 39 for supporting the up-and-down movement of the window glass 38 and the supporting member for supporting the lower end of the glass 38 are made of the sound absorbing plastic plate, it is not necessary to newly provide a structure, and both the sound absorbing and the supporting are supported. There is an advantage of fulfilling the function.

Embodiment 7. FIG. 8 shows an automobile door according to Embodiment 7 of the present invention and is a cross-sectional view of the automobile door taken along a horizontal plane including the central axis of the speaker. In the figure, 50 is a hole for assembly work beside the speaker 5, 51A and 51B are sound absorbing plastic plates, and 52 is an evening cap screw. Sound absorbing plastic plates 51A and 51B
Are installed in pairs so as to close the opening 50, and are fixed to the door inner panel 3 with tapping screws 52. When the diaphragm of the speaker 5 vibrates, air having an opposite phase is sparse and dense on the back surface, and the pressure difference propagates as a sound wave inside the door. The sound wave is repeatedly reflected on the inner wall of the door, and the sound absorbing plastic plate 51 attached to the opening 50.
Reach A and 51B. Sound absorbing plastic plates 51A and 5
Part of the sound wave that hits 1B is absorbed, part is reflected, and the rest is transmitted. Since the transmitted sound wave is expressed as (transmitted wave = incident wave-one absorbed sound wave-reflected wave), the sound wave radiated from the opening 50 to the outside of the door is reduced by sound absorption and reflection. Therefore, the sound waves that interfere with the sound waves radiated in front of the speaker 5 are reduced, and the sound pressure in the low frequency range is prevented from lowering. As in this embodiment, the sound absorbing plastic plate is attached to the opening 50 to prevent the sound wave leaking to the outside of the door by both the sound absorption of the sound absorbing plastic plate and the sound insulation by the reflection. A great effect to prevent is obtained. Further, if the evening plastic screw 52 is loosened and the sound absorbing plastic plates 51A and 51B are removed, there is an advantage that the maintenance work of the mounted parts inside the door can be easily performed.

Embodiment 8. FIG. 9 shows an automobile door according to Embodiment 8 of the present invention, and is a cross-sectional view of the automobile door taken along a horizontal plane including the central axis of the speaker. In the figure, 50 is an opening for assembly work beside the speaker 5, 53 is a sound insulating resin plate, 54 is a sound absorbing plastic plate,
55 is an air layer and 56 is a hinge. The sound absorbing plastic plate 54 is formed in a bowl shape, and is bonded to the sound insulating resin plate 53 with an air layer 55 therebetween. Sound insulation resin plate 53 is hinge 56
It is attached to the door 1 and normally closes the opening 50. When exchanging parts and the like mounted inside the door, the sound insulating resin plate 53 is opened to perform the work. Since it is attached with a hinge 56, opening and closing is easy. Most of the sound waves of opposite phase generated on the back surface of the speaker 5 are absorbed by the sound absorbing structure formed by the sound absorbing plastic plate 54 and the air layer 55. Since the opening 50 is closed by the sound-insulating resin plate 53, sound waves do not pass through the door and leak to the outside. In this embodiment, the sound absorbing plastic plate 54
Since there is the air layer 55 behind, the sound absorption coefficient can be increased, and the frequency at which the sound absorption coefficient is maximized can be selected by changing the thickness of the air layer 55. Therefore, the effect of reducing the sound pressure inside the door is great. Further, since the sound insulating resin plate 53 is closed, the opening 50 can be almost sealed, and the sound wave leaking to the outside of the door can be prevented.

Embodiment 9. FIG. 10 is a ninth embodiment of the present invention.
FIG. 4 is a cross-sectional view of the automobile door according to FIG. 1, taken along a horizontal plane including the central axis of the speaker. In the figure, reference numeral 50 designates an opening 5 for working next to the speaker 5.
Reference numeral 7 is a sound insulating resin plate, and 58 is a Helmholtz resonator. The Helmholtz resonator 58 is integrally molded with the sound insulating resin plate 57, or is molded with another sound insulating resin and is bonded or fitted to be integrated. Helmholtz Resonator 5
8 is configured to have the same resonance frequency as the resonance frequency inside the door, for example. The size can be determined by the above formula (1). For example, if the resonance frequency of the door is 220 Hz,
It is about the size of a beer bottle (small bottle) with a volume of 334 ml. Among the sound waves of opposite phase generated on the back surface of the speaker 5, the frequency component that resonates inside the door and raises the sound pressure is generated by the resonator 5
Sound is absorbed at 8 and the sound pressure decreases. Further, since the opening 50 is closed by the sound insulating resin plate 57, sound waves other than the resonance frequency will not be transmitted and leaked out of the door. In the Helmholtz resonator, the width of the frequency band castle that absorbs sound is narrow, but since a sound absorption force proportional to the square of the wavelength is obtained, it has a great effect on the sound absorption of the bass castle. Since the door has a plurality of openings, a great effect can be obtained by mounting the resonator in the opening close to the position where the sound pressure becomes large at the frequency at which sound is desired to be absorbed.

Embodiment 10. Embodiment 10 of the present invention is shown in FIGS. 11 and 12. FIG. 11 is a front view of the automobile door 1 showing the position of the Helmholtz resonator. In the figure, 60 is a resonator A having a low resonance frequency, and 61 is a resonator B having a high resonance frequency. Reference numeral 5 is a speaker, 9 is an opening above the speaker 5, and 50 is an opening beside the speaker 5. In this embodiment, two types of resonators are installed on the side wall and the bottom surface inside the door toward the rear of the vehicle compartment.

The inside of the door has a length of lm and a height of 0.6.
If the sound velocity is 340 m / s at m and depth of 0.2 m, 170 Hz in the length direction of the door and 28 in the height direction.
A resonance of 3 Hz occurs. At 170 Hz, the sound pressure is high on the side walls before and after the door, and at 283 Hz, the sound pressure is high on the door bottom and the door top. The resonator A installed on the side wall behind the door is designed so that the resonance frequency is 170 Hz,
Absorb sound waves. The resonator B provided on the bottom surface of the door is designed to have a resonance frequency of 283 Hz and absorbs a sound wave of 283 Hz. It is possible to install a plurality of resonators having different resonance frequencies at positions where the sound pressure of the resonance frequency is high, thereby expanding the frequency range for absorbing sound.

FIG. 12 shows the resonator 6 installed inside the door.
FIG. The resonator 60 is manufactured by molding a sound insulating resin material such as polypropylene or a metal having a thickness of about 0.1 mm to 2 mm. As the metal, for example, a cold-rolled steel plate made of the same material as the door body is used. The resonators A and B are attached to the door body by screwing, bonding, or welding in the case of metal. Further, even if the side or bottom of the door body is formed in two steps so as to have a convex shape inside the door, a neck portion having a small-diameter aperture and a cavity are provided, and the resonator is configured by closing from the outside. Good. When the cross-sectional area of the neck portion is S, the length is t, the radius of a circle that is approximately equal to the cross-sectional area of the neck portion is d, and the volume of the hollow portion is V, the resonance frequency is calculated by the above equation (1). When the resonance frequencies of the Helmholtz resonators 60 and 61 are designed in the same manner and attached to the front side wall and the rear side wall of the door, the sound absorption at the resonance frequency becomes large,
Sound absorption effect is enhanced. Also, the sound absorbing effect can be obtained even if the door body is mounted on the inner wall on the vehicle interior side or the inner wall on the vehicle outer side where the sound pressure is large.

Embodiment 11. FIG. 13 shows an automobile door according to an eleventh embodiment of the present invention, and is a cross-sectional view of the automobile door taken along a horizontal plane including the center axis of the spin force. In the figure, 2 is an outer door panel, 3 is an inner door panel, 6 is a waterproof sheet, 68 is a trim, 21 is a stopper for fixing the trim 68 to a small hole of the inner door panel 3, 22 is a speaker grill, and 50 is a speaker 5. A side working aperture, 65 is a sound absorbing plastic block. Reference numeral 66 is a trim plate in which a trim base material such as a hard board is combined with a pad such as polyester foam, and 67 is a skin such as a pinyl chloride sheet. The sound absorbing plastic block 65 is preformed so as to match the shape of the opening 50, and one surface of the sound absorbing plastic block 65 is adhered to the trim plate 66, so that the opening 5 is substantially closed.
0 is blocked.

When the diaphragm of the speaker 5 vibrates, air having opposite phases is sparsely and densely formed on the back surface, and the pressure difference propagates as a sound wave inside the door. A part of the sound waves reaching the sound absorbing plastic block 65 is absorbed and the sound pressure inside the door is reduced. A part of the transmitted sound wave is blocked by the trim plate 66 and the skin 67, and the sound wave leaking to the outside of the door is reduced. Therefore, the sound pressure drop in the low frequency range due to the interference is reduced. According to this embodiment, since the sound absorbing plastic block 65 is attached to the trim 68, there is an advantage that the sound absorbing plastic block 65 blocking the opening 50 can be detached together with the trim 68 and the maintenance work can be facilitated.

In the embodiment shown in FIG. 13, the sound absorbing plastic block 65 is attached to the trim 68 by adhesion.
The same effect can be obtained by screwing the sound absorbing plastic block 65 to the trim plate 66. Further, when the base material forming the trim plate 66 of the trim 68 and the sound absorbing plastic block 65 that closes the opening 50 are integrally formed, the work of bonding and screwing is not necessary, and the number of parts can be reduced. . If the opening 50 is closed with a sound-insulating resin material, there is an effect of preventing sound leakage, but if it is closed with a sound-absorbing plastic block as in this embodiment, an effect of further reducing the sound pressure inside the door can be obtained. .

Embodiment 12. FIG. 14 shows an automobile door according to a twelfth embodiment of the present invention, and is a cross-sectional view of the automobile door taken along a horizontal plane including the center axis of the spin force, and an example in which an air layer is provided on a sound absorbing plastic block. Is shown. In the figure, 70 is a sound absorbing plastic block, 71 is a sound insulating plate, and 72 is a sound absorbing plastic block 7.
It is an air layer formed between 0 and the sound insulating plate 71. The sound absorbing plastic block 70 is fitted, adhered, screwed to the base material of the trim plate 66, or integrally molded with the base material of the trim plate 66 to substantially close the opening 50. The thickness of the air layer 72 is adjusted according to the resonance frequency inside the door, for example. If the dimensions inside the door are lm in length, 0.6 m in height, 0.2 m in depth and 340 m / s in sound velocity, 170 Hz resonance in the door length direction and 283 Hz resonance in the height direction occur.

The sound wave of the opposite phase generated by the diaphragm of the speaker 5 is absorbed by the sound absorbing plastic block 70,
The sound pressure inside the door decreases. The trim 68 blocks the transmitted sound waves and prevents the sound waves from leaking to the outside of the door. Therefore, the sound pressure drop of the bass castle due to the interference is reduced. According to this embodiment, the sound pressure inside the door is reduced, and the sound wave of the opposite phase is prevented from leaking to the outside of the door, and the sound absorbing plastic block 70 can be attached and detached together with the trim 68, which facilitates the maintenance work. There are advantages. Further, since the air layer 72 is provided in the sound absorbing plastic block 70, there is an advantage that the sound absorbing frequency can be adjusted according to the resonance inside the door.

Embodiment 13. FIG. 15 shows an automobile door according to a thirteenth embodiment of the present invention, and is a cross-sectional view of the automobile door taken along a horizontal plane including the center axis of the spin force, showing an example in which a resonator is provided. . In the figure, 73
Is the Helmholtz resonator. The Helmholtz resonator 73 is attached to the trim plate 66 of the trim 68 by bonding, screwing, fitting, or integral molding. The Helmholtz resonator 73 is constructed, for example, to have the same resonance frequency as the resonance frequency inside the door. When the resonance frequency of the door is 220 Hz, the size is about the size of a beer bottle (small bottle) having a volume of 334 ml. In this embodiment, the sound pressure inside the door is reduced by the resonator 73, the sound wave of the opposite phase is prevented from leaking to the outside of the door by the trim 68, and the resonator 73 can be detached together with the trim 68 for maintenance. There is an advantage that the work is easy.

Embodiment 14. 22 and 16 show an automobile door according to Embodiment 14 of the present invention. FIG. 22 is a front view and FIG. 16 is a vertical sectional view thereof. FIG.
In FIG. 5, 5 is a speaker, 105 is an opening just beside the speaker 5, 106 is an opening diagonally opposite to the speaker 5, and 107 is an opening just above the speaker. A sound absorbing plastic block is attached to the inner wall surface of the trim 68 at a position facing the openings 105, 106 and 107. In FIG. 16, 7
5 is a sound absorbing plastic block A, 76 is a sound absorbing plastic block B, 77 is a sound insulating resin plate A, 78 is a sound insulating resin plate B, 79 is an air layer A, and 80 is an air layer B. The sound absorbing plastic block A75 is attached to the trim 68 across the air layer A79, and the air layer A79 is closed by the sound insulating resin plate 77. Sound absorbing plastic block B
76 is attached to the trim 68 across an air layer B78, and the air layer B78 is closed by a sound insulating resin plate 78.
The thickness of the air layers A and B is determined based on the frequency characteristic of sound pressure generated by the resonance inside the door. Set the thickness so that the frequency at which the sound pressure is high matches the frequency at which the sound is absorbed at the mounting position. FIG. 23 shows an example of frequency characteristics of the internal sound pressure of the door. The figure is an example in which the shape of the door of a passenger car of 2000 cc class is approximated and calculated by numerical analysis using the boundary element method. The dimension (inner dimension) is about 0.9 width, 0.54 height, and 0.12 m depth near the center of the door.

Looking at FIG. 23, 189 Hz and 315 Hz
Resonance inside the door appears in and the sound pressure is high.
The 189 Hz resonance is caused by the frequency determined by the longitudinal (horizontal) dimension of the door. The first resonance frequency fr is fr = c / 2w, where c is the speed of sound (m /
s) and w are door widths (inner dimension, m). Speed of sound c is 34
If 0m / s and the door width (inside dimension) is 0.9m, f
r = 189 Hz. At this time, the sound pressure inside the door has a distribution that is high at both ends of the door and is low near the center. Therefore, the sound pressure is high near the holes 106 and 107, and low at the hole 105 near the center. Therefore, in this case, the sound absorbing plastic block B attached to the opening 106
The frequency of 76 is set to 189 Hz. Since the height of the door (inside dimension) is 0.54 m, resonance first occurs at about 315 Hz. At this time, the sound pressure is high near the center of the top and bottom of the door,
The sound pressure is low between the top and bottom. In this case, the frequency of the sound absorbing plastic block A75 attached to the opening 105 near the center of the lower end of the door is set to 315 Hz. The frequency at which the sound absorption coefficient of the sound absorbing plastic block is maximized is adjusted by changing the thicknesses of the air layer A79 and the air layer B80.

In this way, by setting the frequencies of the sound absorbing plastic blocks attached to the openings differently, it is possible to obtain the sound absorbing effect in a plurality of frequency band castles, and the frequencies are set to the resonance and the sound pressure of the interior space of the door. There is an advantage that the sound absorption effect can be enhanced by determining an appropriate frequency from the distribution. Therefore, the backside sound pressure inside the door can be effectively reduced. Further, there is an advantage that the sound absorbing plastic block that closes the opening can be attached and detached together with the trim, and the maintenance work can be facilitated.

Fifteenth Embodiment FIG. 17 is a vertical sectional view of an automobile door according to a fifteenth embodiment of the present invention. In the figure, 81 and 82 are Helmholtz resonators. In this embodiment, a resonator is attached to the inside surface of the trim 68 and located at the opening of the door so that the resonance frequency of the resonator is different. The frequency of the resonator is
Determined based on the sound pressure distribution inside the door. For example, when the resonator 81 is set to 315 Hz and the resonator 82 is set to 189 Hz, sound absorbing effect is obtained in two bands of 315 Hz and 19 OHz. In addition to that, the frequency of the resonator located in the aperture 107 of FIG. 22 is set to 250 Hz, for example. As a result, the sound absorbers with the three openings absorb sound in different frequency bands, and the sound absorption band can be set wide. In addition, in this case, in Obijo near 250Hz,
Since the sound pressure of the opening 107 is higher than that of the openings 105 and 106, there is an advantage that a higher sound absorbing effect can be obtained.

Embodiment 16. FIG. 18 shows Embodiment 16 of the present invention, and is a sectional view of the speaker mounting portion of the rear shelf as seen from the rear direction of the vehicle body. In the figure,
Reference numeral 86 is a rear shelf board which is an interior for covering the rear shelf, 87 is a rear shelf panel for mounting the speaker 5, 88 and 89 are sound absorbing plastic blocks, and 90 and 9 are.
1 is a sound insulating resin plate, 92 is an air layer A, 93 is an air layer B,
94 is a resonator. The lower part of the speaker 5 is a trunk room, and acts as an enclosure for the speaker 5. The sound absorbing plastic block 88 is attached to the rear shelf board 86 with an air layer A92 interposed therebetween, and the air layer A93 is closed by a sound insulating resin plate 90.
The sound absorbing plastic 89 is attached to the rear shelf board 86 with an air layer B93 interposed therebetween.
3 is closed by a sound insulating resin plate 91. The resonator 94 is attached to the rear shelf board 86, and the air layer B93 is covered with a sound insulating resin plate 91. Resonator 94
Is attached to the rear shelf board 86 and installed in the trunk room so as to close the opening. Resonator 94
And the thicknesses of the air layer A92 and the air layer B93 are determined based on the frequency characteristics of the sound pressure generated by the resonance inside the luggage compartment. For example, the size of the luggage compartment
When the length is 950 mm, the width is 1500 mm, and the height is 450 mm, resonance occurs at 113 Hz, 179 Hz, 226 Hz and the like. At 113 Hz, which is the lowest, resonance occurs in the left and right direction of the trunk room, and the sound pressure increases at the left and right ends. Since the resonator 94 resonates at a low frequency even if the internal volume is small, the resonance frequency of the resonator at the left end is set to 113 Hz.

226, which is twice the frequency of 113 Hz
At Hz, the sound pressure is maximized near the center of the trunk room in the left-right direction, and therefore the sound pressure tends to be high at the position of the sound absorbing plastic 88 between the left and right speakers. Therefore, the frequency at which the sound absorption coefficient of the sound absorbing plastic block 88 is maximized is set to 226 Hz. At 179 Hz, resonance occurs in the front and rear direction of the luggage compartment, so the frequency of the sound absorbing plastic block 89 located near the front of the luggage compartment is set to 179 Hz. As a result, sound is absorbed in the three frequency band castles, the band that absorbs sound can be set broadly, and sound is absorbed in a portion with a high sound pressure, so there is an advantage that a higher sound absorbing effect can be obtained.

Embodiment 17. FIG. 19 shows Embodiment 17 of the present invention, which is a horizontal sectional view of an automobile door in which an enclosure is provided behind the speaker of the door. In the figure, 96 is an airtight resin plate such as polypropylene, 97 is a sound absorbing plastic plate, and the speaker box is configured so as to seal the back of the speaker 5.
The speaker box is attached so as to close the opening of the door inner panel 3. The sound wave radiated to the back of the speaker 5 is blocked by the speaker box, so that it does not leak into the door and does not interfere with the sound wave radiated to the front of the speaker 5. Further, since the inner wall of the speaker box is made of a sound absorbing plastic plate 97 and has a sound absorbing property, a standing wave is unlikely to occur in the box, and unevenness in the output sound pressure in front of the speaker 5 is unlikely to occur.

Embodiment 18. 20 and 21 show Embodiment 18 of the present invention. FIG. 20 is a horizontal sectional view of a speaker box, and FIG. 21 is a vertical sectional view taken along the line EE of FIG. In the figure, reference numeral 98 denotes an airtight resin plate which forms an outer wall of the speaker box, and 9
Reference numeral 9 is a sound absorbing plastic plate, 100 is an air layer A, 101 is an air layer B, and 102 is an air layer C. The thickness of the air layer is set according to the standing wave frequency generated inside the speaker box. Inside a rectangular parallelepiped such as a speaker box, standing waves are likely to occur in three directions of length, width, and height, and the frequency is determined by the inner size of the rectangular parallelepiped. The inner dimensions of the speaker box are, for example, 400 mm in length, 120 mm in width, and 25 in height.
0mm, the frequencies are 425Hz, 680Hz, 1
It becomes 417 Hz or the like. The frequency at which the sound absorption coefficient is maximum is 425 Hz for the air layer A100 in the length direction of the speaker box, and 6 for the air layer B101 in the width direction.
80 Hz, 1417 for the air layer C102 in the height direction
Set to be Hz.

In this embodiment, the sound wave radiated behind the speaker 5 is shielded by the speaker box, does not leak inside the door, and does not interfere with the sound wave radiated in front of the speaker 5. Further, since the inner wall of the speaker box absorbs the standing waves in three directions, the standing wave is less likely to be generated in the box, and the output sound pressure in front of the speaker 5 is less likely to be uneven.

[0062]

As described above, according to the present invention, a part of the structure inside the automobile door is made of sound absorbing plastic, and the sound wave radiated from the back of the speaker is absorbed inside the door. Therefore, it is possible to prevent the sound wave on the back surface of the speaker from interfering with the sound wave on the front surface to reduce the sound pressure. Further, since the sound pressure inside the door is reduced, it is possible to prevent the vibration of the mounted product in the interior space of the door and the generation of chattering noise due to the vibration of the door inner panel.

Further, since the sound absorbing member is also used as a structure, the space can be reduced and the number of parts can be reduced.
Cost reduction is possible and the strength of the vehicle is increased,
The safety can be improved.

Further, according to the present invention, since the opening of the door inner panel can be opened and closed by the sound absorbing plastic, the workability of maintenance in the opening is improved.

Further, according to the present invention, since the box using the sound absorbing plastic is formed on the back surface of the speaker, vibration and chatter due to the sound pressure on the back surface of the speaker can be prevented and the performance of the output sound is improved.

Further, by using the Helmholtz resonator, there is an advantage that the generated vibration is quickly attenuated and unnecessary sound is not generated.

Further, by providing an air layer to enhance the sound absorbing effect, and by using a plurality of air layers or resonators having different sound absorbing frequencies, the sound absorbing frequency range can be widened.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an automobile door including a vehicle speaker device according to a first embodiment of the invention.

FIG. 2 is a sectional view of a waterproof cover of a vehicle speaker device according to a second embodiment of the invention.

FIG. 3 is a cross-sectional view of a waterproof cover of a vehicle speaker device according to a third embodiment of the invention.

FIG. 4 is a sectional view of a waterproof cover of a vehicle speaker device according to a fourth embodiment of the present invention.

FIG. 5 is a vertical sectional view of an automobile door including a vehicle speaker device according to a fifth embodiment of the invention.

FIG. 6 is a perspective view of an automobile door according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view showing a main part of FIG. 6;

FIG. 8 is a horizontal sectional view of an automobile door including a vehicle speaker device according to a seventh embodiment of the invention.

FIG. 9 is a horizontal sectional view of an automobile door including a vehicle speaker device according to an eighth embodiment of the invention.

FIG. 10 is a horizontal sectional view of an automobile door including a vehicle speaker device according to a ninth embodiment of the invention.

FIG. 11 is a front view of an automobile door including a vehicle speaker device according to a tenth embodiment of the invention.

FIG. 12 is a perspective view showing a resonator used in Example 10.

FIG. 13 is a horizontal sectional view of an automobile door including a vehicle speaker device according to an eleventh embodiment of the present invention.

FIG. 14 is a horizontal sectional view of an automobile door including a vehicle speaker device according to a twelfth embodiment of the invention.

FIG. 15 is a horizontal sectional view of an automobile door including a vehicle speaker device according to a thirteenth embodiment of the present invention.

FIG. 16 is a vertical sectional view of an automobile door including a vehicle speaker device according to a fourteenth embodiment of the invention.

FIG. 17 is a vertical sectional view of an automobile door including a vehicle speaker device according to a fifteenth embodiment of the present invention.

FIG. 18 is a sectional view of a rear shelf including a vehicle speaker device according to Embodiment 16 of the present invention.

FIG. 19 is a horizontal sectional view of an automobile door including a vehicle speaker device according to a seventeenth embodiment of the invention.

FIG. 20 is a horizontal sectional view of a speaker box of a vehicle speaker device according to Embodiment 18 of the present invention.

21 is a cross-sectional view taken along the line EE in FIG.

FIG. 22 is a front view of an automobile door according to Embodiment 14 of the present invention.

FIG. 23 is a diagram showing an example of frequency characteristics of sound pressure at an opening portion of an automobile door according to Embodiment 14 of the present invention.

FIG. 24 is a view showing the structure of the sound absorbing plastic used in the present invention.

FIG. 25 is a diagram showing a sound absorption coefficient of the sound absorbing plastic used in the present invention.

FIG. 26 is a diagram showing an example of resonance frequencies of a Helmholtz resonator.

FIG. 27 is a diagram showing a relationship between an air layer and a sound absorption coefficient of the sound absorbing plastic used in the present invention.

FIG. 28 is a cross-sectional view of a general electrodynamic speaker.

FIG. 29 is an exploded view showing a conventional vehicle speaker mounting structure.

FIG. 30 is a sectional view showing a mounting structure of a sound absorbing material in a conventional speaker box.

[Explanation of symbols]

1 Automotive Door, 2 Door Outer Panel, 3 Door Inner Panel, 4, 38 Glass, 5 Speaker Body, 8 Trim, 9 Open Holes, 20, 24 Waterproof Cover,
25 Sound insulation resin plate, 26 Sound insulation plastic plate, 27
Air layer, 28, 29 Sound insulation resin plate, 30, 31 Soundproof plastic plate, 32, 33 Air layer, 34 Waterproof cover, 35 Resonator, 37 Soundproof plastic plate, 39
Guide, 40 Guide rubber, 41, 42 Soundproof plastic plate, 44 Inside seal, 45 Outside seal, 50 Open hole, 51A, 51B Sound absorbing plastic plate, 52 Tapping screw, 53 Sound insulating resin plate,
54 sound absorbing plastic plate, 55 air layer, 56 hinge, 57 sound insulating resin plate, 58, 60, 61 resonator,
65 Sound absorbing plastic block, 66 Trim board, 6
8 trim, 70 sound absorbing plastic block, 71
Sound insulation plate, 72 Air layer, 73 Resonator, 75, 76 Sound absorbing plastic block, 77, 78 Sound insulation resin plate,
79, 80 Air layer, 81, 82 Resonator, 86 Rear shelf board, 87 Rear shelf panel, 88, 8
9 sound absorbing plastic block, 90, 91 sound insulating resin plate, 92, 93 air layer, 94 resonator, 96 sound insulating resin plate, 97 sound absorbing plastic plate, 98 sound insulating resin plate, 99 sound absorbing plastic plate, 100, 101, 1
02 Air layer, 105, 106, 107 Open hole, 111
Diaphragm, 112 frame.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H04R 5/02 H04R 5/02 F (72) Inventor Shigeo Ando 2-2 Marunouchi, Chiyoda-ku, Tokyo No. 3 Sanryo Electric Co., Ltd.

Claims (13)

[Claims] 1. A speaker main body supported by a frame in a state where a back surface of a diaphragm is opened, an outdoor wall provided outside a vehicle and an indoor wall provided inside a vehicle are substantially sealed. An enclosure that forms a space and fixes the speaker body to the indoor wall, and uses the space as a vibration space for sound waves radiated from the back surface of the speaker body, the back surface of the speaker body provided in the enclosure. A vehicle speaker device comprising a hard porous sound absorbing plate that absorbs a sound wave of a predetermined frequency among sound waves from the enclosure and has a predetermined structure function in the enclosure. 2. The vehicle speaker device according to claim 1, wherein the hard porous sound absorbing plate is a waterproof wall that prevents water droplets from adhering to the back surface of the speaker body. 3. The vehicle speaker device according to claim 1, wherein the hard porous sound absorbing plate is a reinforcing member that increases the strength of the enclosure. 4. The vehicle speaker device according to claim 1, wherein the hard porous sound absorbing plate is a support member that supports a window glass opening / closing member that can be housed in the enclosure. 5. The speaker device for a vehicle according to claim 1, wherein the hard porous sound absorbing plate is an opening / closing door that closes an opening for work in an enclosure provided on an interior wall. 6. A speaker main body supported by a frame in a state where a back surface of a diaphragm is opened, an outdoor wall provided outside the vehicle and an indoor wall provided inside the vehicle are substantially sealed. An enclosure that forms a space and fixes the speaker main body to the indoor wall, and uses the space as a vibration space for sound waves radiated from the rear surface of the speaker main body, a working opening provided on the indoor wall of the enclosure. A hard porous sound absorbing block that closes the hole to absorb a sound wave of a predetermined frequency among the sound waves from the back surface of the speaker main body and supports an interior material provided facing the indoor side surface of the indoor wall. A speaker device for a vehicle, comprising: 7. The vehicle speaker device according to claim 6, wherein a plurality of hard porous sound absorbing blocks are provided, and each of them has a different sound wave frequency. 8. A space formed by a speaker main body supported by a frame with a back surface of a diaphragm open, an outdoor wall provided outside a vehicle and an indoor wall provided inside a vehicle. A speaker box that is made of a hard porous sound absorbing plate that absorbs sound waves of a predetermined frequency among the sound waves emitted from the back surface of the speaker body, and that has a speaker box that substantially seals the back surface of the speaker body, wherein the speaker body is the vehicle. A speaker device for a vehicle, wherein the speaker box is fixed to an interior wall in the space so as to face the interior. 9. A speaker main body supported by a frame in a state where a back surface of a diaphragm is opened, an outdoor wall provided outside the vehicle and an indoor wall provided inside the vehicle are substantially sealed. A space is formed, the speaker body is fixed to the indoor wall, and an enclosure is provided that uses the space as a vibration space for sound waves radiated from the back surface of the speaker body. A vehicle speaker device characterized by forming a Helmholtz resonance structure. 10. The vehicle speaker device according to claim 9, wherein a plurality of Helmholtz resonance structures are provided, and each of them has a different sound wave frequency. 11. The hard porous sound absorbing plate or block has an air layer formed of these and other members, and any one of claims 1 to 3 and 5 to 8. 2. A vehicle speaker device according to claim 1. 12. The vehicle speaker device according to claim 11, wherein the air layer comprises a plurality of layers having different thicknesses. 13. The hard porous plate or block is used together with a Helmholtz resonance structure formed in another structure, as claimed in any one of claims 1 to 3 and 5 to 7. The vehicle speaker device according to any one of claims 11 and 12.