JPH08133134A - Sound wave advancing direction control device - Google Patents

Abstract

PURPOSE: To control a direction of transmitting a noise or the like from an engine, in an under cover or the like of an automobile. CONSTITUTION: A device has at least two sheets of control plates 19, 20 opposed with a space apart and a plurality of opening parts 21, 22 provided by penetrating through each control sound plate to be opposed to each other, and a plurality of vibration systems, formed by air mass of the opening parts 21, 22 and an air spring of an air layer between the control sound plates 19, 20, are provided to generate a mutual resonance frequency of the vibration system successively increased from an in-surface prescribed part of the control sound plates 19, 20 toward a surface direction one side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound wave traveling direction control device capable of exhibiting a soundproof effect while maintaining air permeability.

[0002]

2. Description of the Related Art Conventionally, as an automobile to which a structure exhibiting a soundproof effect is applied, there is, for example, one shown in FIGS. This automobile 1 has an under cover 5 attached to the lower portion of an engine room 3. The under cover 5
It has a function to improve the aerodynamic characteristics of the lower part of the automobile 1 and to protect the parts in the engine room 3 from pebbles that have been flipped up, and also as a soundproof wall that suppresses the noise emitted from the engine room 3 to the outside of the vehicle. have. The effect of the undercover 5 as a soundproof wall increases as the area increases. However, as the area of the under cover 5 is increased, the lower portion of the engine room 3 is sealed, and the air temperature in the engine room 3 rises. As a result, the temperature inside the engine room 3 becomes high, which may lead to an unfavorable state in terms of component durability. As described above, when installing the undercover 5 in the engine room 3, it is necessary to consider not only the noise suppression aspect but also the thermal aspect.

Therefore, there is a conventional one as shown in FIGS. 21 and 22 (see Japanese Patent Laid-Open No. 85043/1985). That is, in this conventional example, the noise control member 7 is provided in the lower opening of the engine room 3 of the automobile 1 instead of the under cover. This noise control member 7 has a large number of hollow pipe lines 9. The hollow conduits 9 are arranged so that the conduit length is shortened from the central portion of the noise control member 7 to the peripheral portion thereof, and constitute a so-called acoustic lens.
With this structure, the phase of the sound radiated from the engine room 3 is shifted according to the difference in the length of the hollow pipe 9, and the hollow pipes 9 interfere with each other so that they are refracted or converged to have a lens action, thereby concentrating the noise in the lower part of the vehicle. It also has a soundproofing effect of reducing the emission of noise to the outside of the vehicle. Therefore, in this conventional example, noise can be prevented by the noise control member 7, and the heat in the engine room 3 can be released to the outside through the hollow pipe line 9 to lower the air temperature in the engine room 3. be able to.

[0004]

However, when the noise control member 7 as described above is actually mounted on an automobile as an undercover or the like, its size becomes a problem. That is, when used as an undercover in the engine room 3, the minimum ground clearance must be taken into consideration because it is installed between the engine room components such as the engine and the road surface. Actually, the space where the under cover can be installed is the space from the minimum ground clearance to the parts in the engine room. Therefore, the undercover is restricted by its size, especially by its thickness.

Here, the noise control member 7 as described above is
Due to the path length through which the sound passes, that is, the phase shift due to the length of the hollow conduit 9, the transmitted sound and the directly propagating sound that does not pass through the hollow conduit 9 cancel each other out, so that sound is prevented. In order to obtain it, the path length of the hollow pipe line 9 must be made to correspond to the wavelength of the directly propagating sound. Therefore, in order to provide a soundproofing effect to a frequency (800 to 2 KHz) having a relatively long wavelength, which is a problem with the noise outside the vehicle, the length of the hollow pipe line 9 must be long. However, there is a problem that it becomes too thick to be used as an undercover for the engine room 3.

[0006] Further, as an example of reducing the size of the acoustic lens as described above, there are JP-A-62-251799 and JP-A-62-295096. This is to use a viscoelastic body as a conduit and increase the phase difference by controlling the resonance frequency of vibration of the viscoelastic body. With such a structure, the overall size of the device can be reduced. However, it is still large in size to be used as an undercover for automobiles, and since it is made of a viscoelastic material, it is unsuitable for being used in a part such as an undercover, which requires strength against rock bounce.

On the other hand, the applicant of the present application has applied for a sound insulation wall structure as shown in FIGS. 23 and 24 (Japanese Patent Application No. 5719/1993).
No. 6). That is, the sound insulation wall structure 10 includes two sound insulation plates 11 and 13 facing each other with a space therebetween.
The opening 13 is provided at 13 to face each other. The air 15 existing in the openings 11a and 13a has an air mass m, and the air existing between the sound insulation plates 11 and 13 has an air spring 17 having a spring constant k. The air mass m and the air spring 17 vibrate in two degrees of freedom. It constitutes a system. In such a two-degree-of-freedom vibration system, the vibration propagation rate is lower than one at the resonance frequency or higher and enters the vibration isolation region. Therefore, FIG.
1, it is possible to reduce the distance between the sound insulating plates 11 and 13 without taking a long path length, and to use a material having high strength, so that the sound insulating wall structure 10 advantageous as an undercover is obtained. It is possible.

However, in such a sound insulation wall structure 10,
It does not have the function of refracting or converging sound waves, which may limit the sound insulation effect.

Therefore, an object of the present invention is to provide a sound wave advancing direction control device which has a structure having air permeability, which can be further downsized, and which has a higher soundproof effect.

[0010]

In order to solve the above-mentioned problems, the invention of claim 1 is provided with at least two control sound plates facing each other with a space, and penetrating through each of the control sound plates, A plurality of vibrating systems each having a plurality of openings facing each other, each air mass of the openings and an air spring of an air layer between the control sound plates, and a resonance frequency of the vibration system, It is characterized in that the plate is sequentially increased from a predetermined position in the plane toward one side in the plane direction.

According to a second aspect of the present invention, in the sound wave traveling direction control device according to the first aspect, the resonance frequency of the vibration system is sequentially increased from one edge in the surface direction of the control sound plate to the other edge. It is characterized by having done.

According to a third aspect of the present invention, there is provided at least two control sound plates facing each other with a space therebetween, and a plurality of openings provided so as to penetrate each of the control sound plates and facing each other. A plurality of vibration systems consisting of the air mass of the part and the air spring of the air layer between the control sound plates, the resonance frequency of the vibration system from the predetermined position in the plane of the control sound plate to the both sides in the plane direction sequentially. It is characterized by being enlarged.

According to a fourth aspect of the present invention, there is provided the sound wave traveling direction control device according to the third aspect, wherein the resonance frequency of the vibration system is a plane which is orthogonal to the in-plane substantially center line of the control sound plate. It is characterized in that it is gradually increased toward both sides in the direction.

According to a fifth aspect of the present invention, there are provided at least two control sound plates facing each other with a space therebetween, and a plurality of openings provided so as to penetrate each of the control sound plates and facing each other. A plurality of vibrating systems consisting of the air mass of the part and the air springs of the air layer between the control sound plates, and the resonance frequency of the vibrating system is centered at a predetermined position within the surface of the control sound plate, and the in-plane radial direction It is characterized in that it is gradually increased to.

According to a sixth aspect of the present invention, there is provided the sound wave traveling direction control device according to the fifth aspect, wherein the resonance frequency of the vibration system is in the in-plane radiating direction about the in-plane substantially central position of the control sound plate. It is characterized by increasing in size.

The invention of claim 7 is the sound wave traveling direction control device according to any one of claims 1 to 6, wherein the frequency of the sound wave to be soundproofed is the maximum among the resonance frequencies of the respective vibration systems. It is characterized in that it is set to be between the minimum value and the minimum value.

The invention according to claim 8 is the sound wave traveling direction control device according to any one of claims 1 to 7, wherein the opening portion is provided with an extension portion projecting to the opposite side of the control sound plate. Is characterized by.

A ninth aspect of the present invention is the sound wave traveling direction control device according to any one of the first to eighth aspects, wherein the resonance frequency of each vibration system is a plurality of partition walls provided between the control sound plates. Is set by changing each volume of the air layer.

The invention of claim 10 is the sound wave traveling direction control device according to any one of claims 1 to 8, wherein the resonance frequency of each of the vibration systems is set by changing the area of each of the openings. It is characterized by

The invention according to claim 11 is the sound wave traveling direction control device according to claim 8, wherein the resonance frequency of each of the vibration systems is set by changing the protrusion amount of each of the extension portions. .

A twelfth aspect of the present invention is the sound wave traveling direction control device according to any one of the first to eleventh aspects, wherein the control sound plate is at least a part of an undercover of an automobile engine room. And

A thirteenth aspect of the present invention is the sound wave traveling direction control device according to the twelfth aspect, characterized in that the resonance frequency of each of the vibration systems is determined to increase as the distance from the engine increases.

[0023]

According to the invention of claim 1 of the above-mentioned means, in the control sound plate having the opening and facing each other, the air in the opening serves as an air mass and the air layer between the sound insulating plates acts as an air spring. Therefore, a pair of air masses are connected via an air spring to form a two-degree-of-freedom vibration system. Here, when sound enters from one of the vibration systems, this incident wave is transmitted to the other through the vibration system. The phase of the transmitted wave is greatly delayed when the frequency thereof exceeds the resonance frequency of the vibration system. At this time,
Since the resonance frequency of the vibration system is sequentially increased from a predetermined point in the plane of the control sound plate toward one side in the plane direction, the phase of the transmitted wave sequentially progresses from the predetermined point in the plane toward one side in the plane direction. . Therefore, the wavefronts in which the phases of the transmitted waves from the respective vibration systems have the same phase are inclined toward the smaller resonance frequency, and the transmitted waves are refracted toward the side of the vibration system with the smaller resonance frequency. Further, the transmitted wave can be converged by ventilating the control sound plate from one side to the other side through the opening.

According to the second aspect of the invention, in addition to the action of the first aspect of the invention, the transmitted wave can be refracted toward the smaller resonance frequency from the one side edge to the other side edge in the surface direction of the sound insulating plate.

According to the third aspect of the present invention, the refraction due to the phase shift of the transmitted wave and the air permeability due to the opening are maintained, and the transmitted wave has a small resonance frequency from a predetermined position in the plane of the control sound plate to both sides in the plane direction. By refracting towards
The transmitted wave can be converged.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, the transmitted wave is refracted toward the smaller resonance frequency from the in-plane center line of the control sound plate to both sides in the plane direction. Can be converged on a predetermined line.

According to the fifth aspect of the invention, the refraction due to the phase shift of the transmitted wave and the air permeability due to the opening are maintained, and the transmitted wave has a small resonance frequency from a predetermined location in the plane to the in-plane radiation direction. By refracting toward one side, the transmitted wave can be converged to a predetermined point.

In the sixth aspect of the invention, in addition to the action of the fifth aspect of the invention, the transmitted wave is refracted toward the smaller resonance frequency in the in-plane radial direction with the in-plane center position of the control sound plate as the center. , The transmitted wave can be converged to a predetermined point.

According to the invention of claim 7, in addition to the operation of any one of claims 1 to 6, the frequency of the sound wave to be soundproof is between the maximum and minimum of the resonance frequency of the vibration system, and all soundproofing is required. The transmitted wave of the sound wave can be surely refracted.

In the eighth aspect of the present invention, in addition to the operation of any one of the first to seventh aspects of the present invention, since the opening is provided with the extension projecting to the opposite side of the control sound plate, the air mass of the opening is increased. Thus, the resonance frequency can be reduced.

According to the invention of claim 9, in addition to the operation of any one of claims 1 to 8, resonance of each vibration system is achieved by changing each volume of the air layer by a plurality of partition walls provided between the control sound plates. The frequency can be adjusted.

In the tenth aspect of the invention, in addition to the operation of the first aspect of the invention, the resonance frequency of each vibration system can be adjusted by changing the area of each opening.

According to the eleventh aspect of the invention, in addition to the effect of the eighth aspect of the invention, the resonance frequency can be adjusted by changing the protrusion amount of each extension to change the air mass of each opening.

According to the twelfth aspect of the present invention, in addition to the actions of the first to eleventh aspects of the invention, a control sound plate is used as an under cover of the engine room to suppress sound emission from the lower part of the engine room while maintaining ventilation. it can.

According to the thirteenth aspect of the invention, in addition to the action of the twelfth aspect of the invention, the transmitted wave can be refracted toward the lower side of the vehicle to suppress noise emission to the outside of the vehicle.

[0036]

Embodiments of the present invention will be described below.

1, 2, and 3 show an example in which the sound wave traveling direction control device according to the first embodiment of the present invention is applied to an undercover of an automobile. An automobile 1 has an under cover 5 attached to a lower portion of an engine room 3.
The central portion 6 of the under cover 5 is a portion facing directly below the engine 9. Sound wave advancing direction control devices 18 according to an embodiment of the present invention are provided on both sides of the under cover 5 in the vehicle width direction. That is, in this embodiment,
The sound wave traveling direction control device 18 is provided in a part of the under cover 5. However, undercover 5
It is also possible to make the whole of the sound wave traveling direction control device. In addition, the undercover 5 is provided with a sound wave traveling direction control device and FIG.
It is also possible to simultaneously provide 3, 24 sound-insulating plate structures.

The concrete structure of the sound wave traveling direction control device 18 is as shown in FIGS. That is, the sound wave traveling direction control device 18 is provided with two control sound plates 19 and 20 facing each other with a space. The lower control sound plate 20 is formed integrally with the under cover 5. The control sound plate 19 on the upper side is overlapped with the control sound plate 20 on the lower side with a predetermined gap, and is connected by a partition wall described later. The control sound plates 19 and 20 are
A plurality of circular openings 21 and 22 having the same diameter are provided so as to pass through 0 and face each other. The openings 21, 22
Are connected in the longitudinal direction of the vehicle body and are provided in a plurality of rows in the vehicle width direction. The gap between the rows of the openings 21 and 22 in the vehicle width direction is gradually narrowed from the inner side to the outer side in the vehicle width direction. The openings 21 and 22 are provided with extensions 21a and 22a that project toward the opposite sides of the control sound plates 19 and 20 with the same projecting amount. Between the rows of the openings 21 and 22 arranged in the vehicle width direction, both control sound plates 19 and 20 are provided.
A plurality of partition walls 23 are provided in each space. And the space | interval of each partition wall 23 becomes narrow gradually as it goes to the outer side from the vehicle width direction inner side. With such a structure, the air mass of the air 24, 25 in each of the openings 21, 22 and the extensions 21a, 22a and the air spring 27 of the air layer between the control sound plates 19, 20 have two degrees of freedom as shown in FIG. The vibration systems 29a to 29i are provided in plural.

Further, in this embodiment, as described above, the interval between the partition walls 23 is gradually narrowed from the inner side to the outer side in the vehicle width direction so that the resonance frequencies of the respective vibration systems 29a to 29i are controlled to the control sound plates 19 and 20. From a predetermined position in the plane toward one side in the plane direction, that is, from the one end side in the in-plane vehicle width direction of the control sound plates 19 and 20 to the outer end in the one side in the plane direction. There is. The resonance frequency of each vibration system at this time is represented by the following equation.

[0040]

[Equation 1] f ₀ : Resonance frequency c: Sound velocity α: Opening ratio d: Distance between plates t: Plate thickness h: Hole projection amount a: Hole radius That is, the interval between the partition walls 23 between the control sound plates 19 and 20 is gradually reduced. By doing so, the total volume of air between plates in each of the openings 21 and 22 becomes small, so that the opening ratio α
Grows larger. Therefore, according to the equation (1), the control sound plates 19 and 2 are
At 0, the resonance frequencies of the vibration systems 29a to 29i increase from the inner end to the outer end in the vehicle width direction. At this time, the phase of the transmitted wave with respect to the incident wave is largely delayed before and after the resonance frequency, so that as the resonance frequency is increased, the phase gradually advances in the frequency band before and after the resonance frequency.

This will be described with reference to FIG. FIG. 6 is a graph showing changes in phase with changes in frequency. FIG. 6 shows five curves with different resonance frequencies. When viewed at the phase (-180 degrees), the resonance frequency on the left side is small and increases toward the right side. That is, in the case of the curved line on the left side in correspondence with the above embodiment, the interval between the partition walls 21 is large and the interval becomes narrower toward the right side. Corresponding to FIG. 4, it corresponds to the vibration system on the inner side in the vehicle width direction. What is done is the curve on the left side of FIG. 6, and the resonance frequency of the vibration system 29a etc. on the outside in the vehicle width direction is on the right side of FIG. That is, as is clear from FIG. 6, the phase (-180
Since the phase greatly lags before and after the resonance point, the phase gradually advances in the frequency band around the resonance point when the resonance frequency is gradually increased from the curve on the left side of FIG. 6 to the curve on the right side. It will be. From this, the wavefront 31 in which the phases of the transmitted waves from the openings 21 and 22 are the same as in FIG. 5 is as shown in FIG. That is, the curve 33 in FIG.
Reference characters a to 33i show the progress of the transmitted sound waves from the respective vibration systems 29a to 29i. Therefore, these curves 33a-33
The tangent line connecting i becomes the wavefront 31 of the same phase. Therefore, the wavefront 31 in which the phases of the transmitted waves from the openings 21 and 22 have the same phase is refracted toward the smaller resonance frequency.

FIG. 7 is an iso-sound pressure diagram of the transmitted wave obtained by calculation. In FIG. 7, the sound wave traveling direction control device 18
Is set so that the resonance frequency gradually decreases from the right side to the left side. As shown in FIG. 7, the transmitted wave typically represented by the arrow B with respect to the incident wave typically represented by the arrow A is refracted toward the smaller resonance frequency. Therefore, in the sound wave traveling direction control device 18 provided as shown in FIG. 3, the incident wave A which is the noise radiated from the engine 9 is reduced by decreasing the resonance frequency of the vibration system toward the vehicle width direction center side.
Is refracted downward by the sound wave traveling direction control device 18 to form a transmitted wave B, and the noise radiated to the side of the vehicle is significantly reduced. The transmitted wave B of each vibration system 29a to 29i is
The phase is shifted with respect to the incident wave A, and each vibration system 29a ...
It interferes with the sound wave that has propagated without passing through 29i, and exerts a sound deadening effect. Therefore, also from this point, soundproofing can be achieved, and the overall soundproofing performance is high. Further, in such a sound wave traveling direction control device 18, each of the vibration systems 29a-2
Since the air mass and air spring of 9i do not need to be so large for those having a relatively high resonance frequency,
The size can be reduced as a whole. Therefore, the sound wave progression control device 18 can have a thickness of about 30 mm, and can be sufficiently miniaturized even when applied to the under cover 5. Further, the undercover 5 including the sound wave advancing direction control device 18 can be made to withstand pebbles by using a material having a relatively high strength such as polypropylene (pp).

It should be noted that the problem of external noise is 800 to 2
Since it is KHz, the minimum resonance frequency of the vibration systems 29a to 29i is set to 800 Hz or less and the maximum resonance frequency is set to 2 KHz or more so that the phase difference becomes large in this frequency band. As a result, a sound wave frequency of 800 to 2 KHz that should be sound-proofed depending on the engine speed
You can get a big effect with. Further, in the above-described embodiment, the openings 21 and 22 are circular, but the same effect can be obtained even if the openings 21 and 22 have a shape other than a circular shape.

Next, another embodiment will be described with reference to FIGS. The same components as those of the first embodiment will be designated by the same reference numerals and will not be described.

FIG. 8 is a perspective view of the sound wave traveling direction control device 35 according to the second embodiment. This FIG. 8 shows the first
FIG. 5 is a perspective view of the embodiment similar to FIG. 4. In the second embodiment, the interval between the partition walls 23 of the respective vibration systems 37a to 37h is uniform inside and outside the vehicle width direction. On the other hand, the openings 39a to 39h and the openings 41a to 41h are set such that the opening diameters gradually increase from the openings 39a, 41a on the inner side in the vehicle width direction to the openings 39h, 41h on the outer side in the vehicle width direction. ing. Also, the openings 39a to 39h
The diameters of the extension portions 40a to 40h of each of the opening portions 41a to 41h and the extension portions 42a to 42h of each of the opening portions 41a to 41h are also equal to
It is formed corresponding to 1a to 41h. The amount of protrusion of the extension portions 40a to 40h and 42a to 42h, the partition wall 23
The spacing between them is uniform. As a result, each vibration system 37a-
37h is set so that the resonance frequency increases from the inner side in the vehicle width direction to the outer side in the vehicle width direction. That is, as shown in FIG. 9, the phase of the transmitted wave with respect to the incident wave is largely delayed before and after the resonance point, and therefore, as the resonance frequency is increased, the phase gradually advances in the frequency bands before and after the resonance frequency. Therefore, the transmitted wave of the sound wave traveling direction control device 35 has a small resonance frequency and a small degree of phase advance.
The light is refracted toward the smaller diameter of 9h and 41a to 41h. Therefore, also in the second embodiment, it is possible to obtain substantially the same operational effects as in the first embodiment. Moreover, in this embodiment, a larger phase change can be made by changing the size of the opening, and the wavefront of the same phase can be tilted to the one having a smaller resonance frequency than that in the first embodiment. Therefore, the noise from the engine can be refracted further toward the vehicle width direction center side by the sound wave traveling direction control device 35, and a greater effect can be obtained. Further, in the second embodiment, by changing the distance between the partition walls 23 in the same manner as in the first embodiment, the air layer volume of each of the vibration systems 37a to 37h is also changed, so that a larger effect can be obtained.

FIG. 10 is a perspective view showing a sound wave traveling direction control device 43 according to the third embodiment. In the third embodiment, the extension parts 47a to 47h of the respective vibration systems 45a to 45h,
Each resonance frequency is set by changing the protrusion amount of 49a to 49h. That is, extending portions 47a to 47h, 49 extend from the vibration system 45a on the inner side in the vehicle width direction to the vibration system 45h on the outer side.
The amount of protrusion of a to 49h is gradually shortened, and the amount of protrusion of the extension portion 49h of the vibration system 45h at the vehicle width direction outer end is zero.
The diameter of the opening and the interval between the partition walls are uniform. Therefore, the resonance frequencies of the vibration systems 45a to 45h are sequentially increased from one edge in the surface direction of the control sound plates 13 and 15 to the other edge. That is, as shown in FIG. 11, the phase of the transmitted wave changes and the phase advances as the amount of protrusion of the extended portion decreases. Therefore, the transmitted wave of the sound wave traveling direction control device 43 has a low resonance frequency and a phase advance degree that is small in the extension portion 4.
It refracts toward the larger protrusion amount of 7a to 47h and 49a to 49h. Therefore, also in this embodiment, the first
It is possible to obtain substantially the same operational effects as the embodiment. Further, in this embodiment, the extension portions 47a to 47h and 49a to 49 are provided.
Since the resonance frequency is changed by changing the protrusion amount of h, the control sound plates 19 and 20 themselves can be shared with those having no change in the extension. Further, in the third embodiment, a greater effect can be obtained by using the change of the air layer volume of the first embodiment and the change of the opening diameter of the second embodiment together.

12 to 16 show a fourth embodiment of the present invention. In this embodiment, a sound wave traveling direction control device 51 is provided at the center of the under cover 5 in the vehicle width direction. The sound wave traveling direction control device 51 covers almost the entire length of the engine 9 in the front-rear direction of the vehicle body and is provided over a range slightly wider than the region corresponding to the engine 9 in the vehicle width direction. FIG. 1 of this sound wave traveling direction control device 51
The vibration systems 53a to 53g shown by reference numerals 5 and 16 are control sound plates 1
Vibration system 53d located on the center line in the vehicle width direction of 9, 20
Of the control walls 19, 20 having the widest interval between the partition walls 23 of the
The intervals between the partition walls 23 are set to gradually decrease toward both sides in the plane direction. The diameter of the opening and the amount of protrusion of the extension are uniform. Therefore, in this embodiment, the resonance frequencies of the vibration systems 53a to 53g are sequentially increased from a predetermined position in the plane of the control sound plates 19 and 20 toward both sides in the plane direction. More specifically, the control sound plates 19 and 20 are set to be gradually larger from the in-plane center line to both sides in the plane direction orthogonal to the center line, that is, to both sides in the vehicle width direction. Therefore, in this embodiment, the volume of the air layer between the control sound plates 19 and 20 is large in the central vibration system 53d and gradually decreases on both sides thereof. Therefore, from the above equation (1), the vibration systems 53a to 53a
The resonance frequency of g is minimum in the central vibration system 53d and gradually increases toward both sides thereof. That is, as shown in FIG. 16, the wavefront 31 in which the phases of the transmitted waves B of the respective vibration systems 53a to 53g have the same phase is inclined so as to gradually move away from the control sound plates 19 and 20 in the vehicle width direction central part to both sides thereof. Becomes Then, the incident wave A that is the noise from the engine 9
Becomes a transmitted wave B that converges toward the center of the control sound plates 19 and 20, and the noise radiated to the side of the vehicle is significantly reduced. Therefore, also in this embodiment, it is possible to obtain the same effects as the above-mentioned embodiments. Moreover, in this embodiment, since the sound wave traveling direction control device 51 having the openings 21 and 22 below the engine 9 faces each other, the waste heat operation of the engine 9 can be performed more smoothly. Further, in this embodiment, the resonance frequency can be adjusted by changing the diameter of the opening, changing the amount of protrusion of the extension, or by using these together. Further, by combining the change of the opening diameter and the like, a larger effect can be obtained.

17 and 18 show the fifth embodiment of the present invention. The sound wave traveling direction control device 55 of this embodiment has a predetermined position in the plane of the control sound plate 15, that is, the control sound plate 19,
The vibration systems 57b, 57c, and 57d are provided on the circumferences having different diameters around the vibration system 57a at the center of 20. The partition walls 59a to 59d of this embodiment are circular when viewed from the surface direction of the control sound plates 19 and 20.
Further, the intervals between the partition walls 59a to 59d are set to be gradually narrowed in the radial direction. The opening diameter,
The amount of protrusion of the extension is uniform. Therefore, the central vibration system 57a
Has the largest air layer volume of the vibration system 57b, 57c, 57
It is set so that it becomes smaller in the radial direction of d.
Therefore, the resonance frequency of each of the vibration systems 57a to 57d is set to be smallest in the central vibration system 57a and sequentially increase in the radial direction. Therefore, as shown in FIG. 18, the wavefront 31 having the same phase is inclined from the center of the sound insulating plates 13 and 20 in the radial direction. By setting the sound wave traveling direction control device 55 such that the central vibration system 57a is located directly below the engine, the incident wave A, which is the noise of the engine, is transmitted to the central side of the control sound plates 19 and 20 as a transmitted wave B. It can be converged, and the noise radiated to the side of the vehicle can be significantly reduced. Moreover, in this embodiment, not only the noise in the vehicle width direction but also in the vehicle front-rear direction, the control sound plates 19, 2
It can be converged to the center side of 0, and noise emission in the vehicle front-rear direction can be reduced. Also in this embodiment, the resonance frequency can be set by changing the diameter of the opening or the protruding amount of the extension, and by using them in combination. Then, by changing the diameter of the opening and the like, a greater effect can be obtained.

[0049]

As is apparent from the above, according to the first aspect of the invention, the incident wave can be refracted to the one having the smaller resonance frequency with respect to the surface direction of the control sound plate, and the sound wave traveling direction is controlled. be able to. Therefore, when the incident wave is noise or the like, by controlling the direction of the incident wave, it is possible to reduce sound leakage and the like, thereby reducing noise and providing a soundproof function. Moreover, the size of the vibration system does not become large, and it is possible to reduce the size as a whole, which facilitates application as an undercover for an automobile engine room. In addition, breathability can be ensured.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the incident wave can be refracted in the direction of one side edge of the control sound plate in the plane direction. Therefore, when the incident wave is noise or the like, it is possible to suppress the noise from leaking to the side of the other side and reduce the noise.

According to the third aspect of the invention, the transmitted wave can be converged by refracting the incident wave from both sides of the control sound plate in the plane direction to a predetermined position in the plane and transmitting the refracted wave. Therefore, when the incident wave is noise or the like, noise can be collected from both sides in the plane direction toward a predetermined location within the surface of the sound insulation plate, and noise leakage can be suppressed.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, the incident wave is refracted and transmitted from both sides in the plane direction with respect to the in-plane center line of the control sound plate, and is transmitted.
The transmitted wave can be converged. Therefore, the incident wave can be transmitted so as to be collected on the center line side of the control sound plate.

According to the fifth aspect of the present invention, the incident wave is transmitted to and collected from a predetermined position in the plane of the control sound plate from the in-plane radiation direction toward the predetermined position in the plane, whereby leakage of noise and the like can be suppressed.

According to the invention of claim 6, in addition to the effect of the invention of claim 5, the incident wave can be converged so as to be collected toward the central position side in the plane of the control sound plate.

According to the invention of claim 7, the frequency of the sound wave to be soundproofed is set so as to be between the maximum and minimum resonance frequencies of the vibration system, so that the incident wave of the soundwave to be soundproofed can be reliably performed. It is possible to surely prevent sound leakage by refracting the light and transmitting it.

According to the invention of claim 8, in addition to the effect of any one of the inventions of claims 1 to 7, the mass of air in the opening can be increased, and a lower resonance frequency is created to expand the control width. You can

According to the ninth aspect of the invention, in addition to the effect of any one of the first to eighth aspects, the volume of each air layer can be changed to set the resonance frequency by setting the interval between the partition walls. Therefore, the resonance frequency can be easily changed without requiring any special member.

According to the invention of claim 10, in addition to the effect of any one of claims 1 to 8, the structure is extremely simple because the resonance frequency is set by changing the area of the opening portion. Also in this case, the difference in the area of the opening can be easily visually judged, and the directionality thereof can be easily set correctly.

According to the eleventh aspect of the invention, in addition to the effect of the eighth aspect of the invention, the resonance frequency is set by changing the protrusion amount of the extension portion, so that the structure is simple and the control sound plate itself is shared. It is also possible.

According to the twelfth aspect of the invention, since the control sound plate is at least a part of the undercover of the automobile engine room, it is possible to suppress the leakage of noise from the engine room. In addition, the device can be made compact and can be applied to the undercover without difficulty. Further, the opening portion can also promote the action of waste heat from the engine room.

According to the thirteenth invention, in addition to the effect of the twelfth invention, noise from the engine can be transmitted from the side away from the engine to the engine side. Therefore, it is possible to prevent the engine noise from being radiated to the side of the vehicle.

[Brief description of drawings]

FIG. 1 is a schematic perspective view seen from a side of an automobile to which a first embodiment is applied.

FIG. 2 is a bottom view of an automobile to which the first embodiment is applied.

FIG. 3 is a schematic sectional view of an automobile to which the first embodiment is applied.

FIG. 4 is a perspective view of a sound wave traveling direction control device according to the first embodiment.

FIG. 5 is an operation explanatory view.

FIG. 6 is an explanatory diagram of a phase change.

FIG. 7 is a sound pressure diagram of a transmitted wave according to the first example.

FIG. 8 is a perspective view of a sound wave traveling direction control device according to a second embodiment.

FIG. 9 is an explanatory diagram showing a change in phase according to the second embodiment.

FIG. 10 is a perspective view of a sound wave traveling direction control device according to a third embodiment.

FIG. 11 is an explanatory diagram of a phase change according to the third embodiment.

FIG. 12 is a schematic perspective view of an automobile to which the fourth embodiment is applied, as seen from the side.

FIG. 13 is a bottom view of an automobile to which the fourth embodiment is applied.

FIG. 14 is a schematic sectional view of an automobile to which a fourth embodiment is applied.

FIG. 15 is a perspective view of a sound wave traveling direction control device according to a fourth embodiment.

FIG. 16 is an explanatory view of the operation of the fourth embodiment.

FIG. 17 is a perspective view of a sound wave traveling direction control device according to a fifth embodiment.

FIG. 18 is an explanatory view of the operation according to the fifth embodiment.

FIG. 19 is a perspective view seen from the side of an automobile having a conventional undercover.

FIG. 20 is a bottom view of an automobile having a conventional undercover.

FIG. 21 is a sectional view of an engine room to which another conventional example is applied.

FIG. 22 is a perspective view of a noise control member according to another conventional example.

FIG. 23 is a perspective view of a main part of the sound insulation wall structure previously applied.

FIG. 24 is a cross-sectional view of the sound insulation wall structure previously applied.

[Explanation of symbols]

 1 Car 3 Engine Room 5 Undercover 9 Engine 18 Sound Wave Direction Control Device 19 Control Sound Plate 20 Control Sound Plate 21 Opening 21a Extension 22 Opening 22a Extension 23 Partition Wall 29a-29i Vibration System 35 Sound Wave Direction Control Device 37a-37h Vibration system 39a-39h Opening 41a-41h Opening 43 Sound wave advancing direction control device 45a-45h Vibration system 47a-47h Extension part 49a-49h Extension part 51 Sound wave advancing direction control device 53a-53g Vibration system 55 Sound wave advancing Direction control device 57a-57d Vibration system 57a-57d Partition wall

Claims (13)

[Claims] 1. At least two control sound plates facing each other at intervals, and a plurality of openings provided so as to penetrate through each of the control sound plates and facing each other, wherein an air mass of the openings is provided. And a plurality of vibration systems each including an air spring in an air layer between the control sound plates, wherein the resonance frequency of the vibration system is sequentially increased from a predetermined position within the surface of the control sound plate toward one surface direction. A sound wave traveling direction control device. 2. The sound wave traveling direction control device according to claim 1, wherein the resonance frequency of the vibration system is sequentially increased from one side edge portion in the surface direction of the control sound plate to the other side edge portion. A sound wave traveling direction control device. 3. An air mass of the opening, comprising: at least two control sound plates facing each other at a distance; and a plurality of openings penetrating each of the control sound plates and facing each other. And a plurality of vibration systems each including an air spring of an air layer between the control sound plates, wherein the resonance frequency of the vibration system is sequentially increased from a predetermined position in the surface of the control sound plate toward both sides in the surface direction. Characteristic sound wave traveling direction control device. 4. The sound wave traveling direction control device according to claim 3, wherein the resonance frequency of the vibration system is directed from a substantially in-plane centerline of the control sound plate to both sides in a plane direction orthogonal to the centerline. The sound wave traveling direction control device is characterized in that it is sequentially enlarged. 5. At least two control sound plates facing each other at intervals, and a plurality of openings provided to penetrate each of the control sound plates and facing each other, wherein the air mass of the openings is And a plurality of vibration systems consisting of air springs in the air layer between the control sound plates, and the resonance frequency of the vibration system is increased in the in-plane radial direction centering on a predetermined position in the plane of the control sound plate. A sound wave traveling direction control device characterized by the above. 6. The sound wave traveling direction control device according to claim 5, wherein the resonance frequency of the vibration system is increased in the in-plane radiation direction about the in-plane substantially central position of the control sound plate. A sound wave traveling direction control device. 7. The sound wave traveling direction control device according to claim 1, wherein the frequency of the sound wave to be soundproofed is maximum or minimum among the resonance frequencies of the respective vibration systems. And a sound wave advancing direction control device. 8. The sound wave traveling direction control device according to claim 1, wherein the opening portion is provided with an extension portion that projects toward the opposite side of the control sound plate. Sound wave direction control device. 9. The sound wave traveling direction control device according to claim 1, wherein a resonance frequency of each of the vibration systems is generated by a plurality of partition walls provided between the control sound plates. The sound wave traveling direction control device is characterized in that the volume is set by changing each volume. 10. The sound wave traveling direction control device according to claim 1, wherein the resonance frequency of each vibration system is set by changing an area of each opening. Sound wave traveling direction control device. 11. The sound wave traveling direction control device according to claim 8, wherein the resonance frequency of each of the vibration systems is set by changing a protrusion amount of each of the extension portions. apparatus. 12. The sound wave traveling direction control device according to claim 1, wherein the control sound plate is at least a part of an undercover of an automobile engine room. Direction control device. 13. The sound wave advancing direction control device according to claim 12, wherein the resonance frequency of each of the vibration systems is determined so as to increase as the distance from the engine increases. .