JPH108939A - Silencer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance transmitting efficiency of vibration and attain downsizing of a device. SOLUTION: This device comprises a resonator 3 having a vibrating plate 5 and its peripheral low rigidity member 7 and an amplification transmitting mechanism 10 amplifying vibration from a noise source vibrating surface transmitted to the vibrating plate 5 of this resonator 3. The amplification transmitting mechanism 10 is constituted by a lever 12, and, in accordance with lever ratio, vibration is magnified and transmitted to the vibrating plate 5. In a radiated sound from the resonator 3, a phase is inverted in a resonance frequency serving as a boundary, in this way, and a noise is negated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reduction device for reducing noise radiated from a vibration surface of a structure.

[0002]

2. Description of the Related Art As a conventional silencer, Japanese Patent Laid-Open Publication No.
There is one as disclosed in Japanese Patent No. 5485.

As shown in FIG. 17, two parallel plates 109a and 109b are connected to each other through a plurality of cylindrical portions 111, while each plate 109a,
A plurality of circular holes 110 are provided in the same position in 109b, thereby forming a resonator 103 between the upper and lower plates 109a and 109b. The resonance frequency of the resonator 103 is set lower than the frequency of the noise for noise reduction.

When noise is incident on the plate 109a of this silencer, the noise passing through the cylinder 111 becomes a transmitted wave having the same phase as the incident wave, while the noise passing through the resonator 103 is lower than the resonance frequency of the resonator 103. At a low frequency, the transmitted wave has the same phase as the incident wave, but at a frequency higher than the resonance frequency, the transmitted wave has a phase opposite to that of the incident wave.

Therefore, in a frequency band higher than the resonance frequency of the resonator 103, the transmitted waves that have passed through the cylindrical portion 111 and the resonator 103 cancel each other out of phase with each other. Is to be reduced.

[0006]

However, such a silencer is not suitable for silencing noise radiated from the engine, for example, by disposing the silencer in a narrow space between the engine and the engine cover. That is, since it is necessary to fill most of the vibration surface where noise is generated, the silencer becomes large, the weight increases, and above all, if there is not enough space, the mounting itself becomes impossible. .

The applicant of the present invention has disclosed in Japanese Patent Application No. Hei 8-64642 that a vibration plate of a resonator is mechanically vibrated in response to the vibration of a structural surface serving as a noise source, and the resonance frequency of the resonator is set at the boundary. A noise reduction device that reduces noise by canceling noise from a vibrating surface by radiated sound from a resonator whose phase is inverted is proposed. By setting the resonance frequency of the resonator slightly lower than the vibration frequency to be silenced,
Vibration released from the vibrating surface is suppressed. In this case, since the motion of the vibrating surface is mechanically transmitted to the resonator, the energy loss is small, and even if the resonator is relatively small, the vibration is reduced. Noise can be effectively reduced.

It is an object of the present invention to further improve such a silencer, improve the transmission efficiency of vibration, and further reduce the size of the device.

[0009]

A first aspect of the present invention is a silencer for reducing noise radiated from a vibration surface of a noise source, comprising a resonator having a diaphragm and a low-rigidity member around the diaphragm. An amplification transmission mechanism for amplifying and transmitting vibration from the noise source vibration surface to the diaphragm of the resonator.

According to a second aspect of the present invention, the amplification transmitting mechanism includes a lever having a base connected to a housing of the resonator, a protrusion contacting the diaphragm at a distal end of the lever, and a noise at a base end of the lever. A projection that contacts the vibration surface of the source, and expands the input vibration according to the lever ratio and transmits it to the diaphragm.

In a third aspect of the present invention, a concave portion for storing a lever is formed in a part of the diaphragm, and a lower surface of the lever is formed substantially identical to a lower surface of the diaphragm except for the concave portion.

According to a fourth aspect of the present invention, the lever is disposed in an internal space of the resonator, and a base end side protrusion of the lever comes into contact with a vibration surface of an external noise source through an opening formed in the diaphragm. Have been.

According to a fifth aspect of the present invention, the amplification transmission mechanism is configured by connecting at least two levers in series, and is configured to expand the transmission ratio of vibration to at least double according to each lever ratio. .

In a sixth aspect, the amplification transmission mechanism is configured by arranging at least two levers in parallel.

According to a seventh aspect, at least two resonators having different resonance frequencies are provided as the resonators.

According to an eighth aspect of the present invention, there is provided an engine cover for covering an upper surface of the engine with a predetermined gap, wherein the resonator is attached to a part of the engine cover, and an amplification transmission mechanism controls the vibration of the engine noise generating vibrator. It is configured to transmit to the diaphragm.

[0017]

According to the first aspect of the invention, the vibration from the noise source vibration surface is directly and amplified transmitted to the vibration plate of the resonator via the amplification transmission mechanism, and the vibration plate is greatly vibrated by the vibration energy. Thereby, the internal space of the resonator is excited very efficiently. The large-level radiated sound from the resonator caused by this excitation has its phase inverted at the resonance frequency of the resonator, and therefore the noises are canceled by the opposite-phase radiated sound, and the noise in a predetermined frequency region Is effectively reduced.

According to the second aspect of the invention, the vibration is expanded and transmitted by the lever action corresponding to the lever ratio, and the diaphragm is vibrated greatly, so that an efficient silencing function can be obtained.

In the third and fourth aspects, the distance between the lower surface of the diaphragm and the noise vibration surface can be reduced, and the resonator can be arranged in a narrow space.

In the fifth aspect of the present invention, the lever ratio is further amplified by the plurality of levers, whereby the diaphragm is further vibrated even more, and a high noise reduction performance can be exhibited even with a small resonator.

In the sixth aspect, since the vibration is transmitted by the plurality of levers, the diaphragm can be vibrated reliably, and a reliable noise reduction performance can be obtained.

According to the seventh aspect, the sound deadening function can be exhibited in a wide frequency band corresponding to the resonance frequency of the resonator.

In the eighth aspect, the noise radiated from the engine can be effectively silenced by the function of the resonator disposed between the engine cover and the engine.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 to 4, an engine cover 2 is mounted on the upper portion of the engine 1 so as to cover the engine 1 with a predetermined gap. Engine cover 2 is engine 1
Is formed in a shape similar to the shape of the upper surface of the engine 1 and is surrounded by a vertical end wall 2a on the outer periphery thereof. It is supported via a plurality of buffer supports 6.

A resonator 3 is provided on the inner surface of the upper part of the engine cover 2.
Is attached. In the resonator 3, the bottom surface of a thin cylindrical housing jig 4 is released, and a diaphragm 5 is stretched on this release surface. The disk-shaped diaphragm 5 is connected to the housing jig 4 via an annular low-rigid member 7 around the disk-shaped diaphragm 5, and defines a space 9 inside the housing jig 4. A plurality of openings 8 for communicating the internal space 9 with the outside are formed in a part of the diaphragm 5. The resonance frequency of the resonator 3 is set to be somewhat lower than the noise frequency to be silenced.

The vibration plate 5 is provided with an amplification transmission mechanism 11 for mechanically amplifying and transmitting vibration from the noise generating vibration body 10 on the upper surface of the engine 1. The amplification transmission mechanism 11 is provided with a lever 12 on a part of the outer wall of the housing jig 4.
The lever 12 is extended so that the lever 12 is parallel to the diaphragm 5 and the distal end thereof reaches almost the center of the diaphragm 5, and a projection 13 projecting from the distal end toward the diaphragm 5 is attached to the diaphragm 5. The projection 14 is provided on the base end side of the lever 12 toward the noise-generating vibrator 10, and the projection 14 is brought into contact with the surface of the noise-generating vibrator 10. In addition, an elastically deforming portion 15 formed of a notch is formed on the base end side of the lever 12 to facilitate the swinging of the lever 12.

The operation is described below.

The vibration of the engine 1 is transmitted to the noise generating vibrator 10 and causes the film to vibrate to generate noise. This vibration is transmitted to the diaphragm 5 of the resonator 3 via the lever 12 as the amplification transmission mechanism 11.

That is, the vibration from the noise generating vibrating body 10 is input to the lever 12 via the projection 14 and the tip projection 13
Is transmitted to the diaphragm 5 through the lever 1 in this case.
Numeral 2 functions as a lever having a base point connected to the housing jig 4 as a fulcrum, a projection 14 in contact with the noise generating vibrating body 10 as a power point, and a projection 13 in contact with the diaphragm 5 as an operation point. The vibration of the noise-generating vibrating body 10 is amplified and transmitted to the diaphragm 5 according to the amplification factor according to the ratio of the distance to the motor, that is, the lever ratio.

As shown in FIG. 5, since the diaphragm 5 is connected to the housing jig 4 through the surrounding low-rigid member 7, the vibration amplified by the lever 12 causes
Greatly excites the internal space 9. Therefore, the diaphragm 5 vibrates the internal space 9 in the same phase as the noise radiated from the noise generating vibrating body 10, thereby generating a radiated sound from the opening 8 of the resonator 3.

This radiated sound has the same phase as the noise generating vibrator 10 in a frequency band where the vibration of the noise generating vibrator 10 is lower than the resonance frequency of the resonator 3, but has a phase in a frequency band higher than the resonance frequency. Invert. Therefore, the resonator 3
In the region higher than the resonance frequency, the engine vibration noise is canceled by the radiated sound of the opposite phase radiated from the resonator 3, and the noise is reduced so that the noise level in the frequency band somewhat higher than the resonance frequency is most reduced. .

In this case, the diaphragm 5 is greatly vibrated by the lever action of the lever 12, and even if the resonator 3 is small, a large level of radiated sound having an opposite phase can be generated. Can be reduced.

As a result, the noise directly penetrating the engine cover 2 and the engine cover 2 and the engine 1
The noise from the engine 1 passing between the two is very effectively silenced as shown in FIG.

In FIG. 6, what is shown as an example of the prior application is a sound deadening characteristic according to Japanese Patent Application No. 8-64642 filed by the present applicant.

Next, the embodiment shown in FIGS. 7 and 8 will be described. This is the lever 1 that constitutes the vibration amplification transmission mechanism 11.
2 is a storage recess 1 formed on the lower surface of the diaphragm 5 of the resonator 3.
6 in which the distance between the diaphragm 5 and the noise generating vibrating body 10 is reduced.

Storage recess 16 formed in part of diaphragm 5
Is formed in a thin rectangular parallelepiped capable of storing the lever 12 in its entirety, so that the lower surface of the lever 12 substantially matches the entire lower surface of the diaphragm 5.

As a result of this configuration, the clearance between the upper surface of the engine 1 and the engine cover 2 can be further reduced, and the resonator 3 can be efficiently disposed even in a narrow space. .

FIGS. 9 and 10 show still another embodiment. In this example, the lever 12 constituting the amplification transmission mechanism 11 is arranged in the internal space 9 of the resonator 3 to further improve the space efficiency. ing.

That is, the base end of the lever 12 is connected to a part of the inner wall of the housing jig 4 in the internal space 9, and the lever 12 extends parallel to the diaphragm 5 inside the resonator 3.
The projection 13 at the tip is brought into contact with the diaphragm 5 from the inside. In addition, the projection 14 that comes into contact with the noise generating vibrating body 10 is projected outside the resonator 3 through the opening 8 provided in the diaphragm 5.

In this case, the noise generating vibrating body 10
For example, when the projection 14 is pushed upward by the film vibration of the above, the projection 13 at the tip of the lever 12 also moves upward,
In this state, the projection 13 is set in a state in which the diaphragm 13 is slightly pressed into the diaphragm 5 at the initial position so as to keep the contact with the diaphragm 5 even in this state.

Since the lever 12 is arranged in the internal space 9 of the resonator 3 in this manner, the clearance between the lower surface of the resonator 3, that is, the vibration plate 5 and the noise generating vibrating body 10 of the engine 1 can be reduced accordingly. As a result, the space efficiency is improved as in the second embodiment.

Next, the embodiment shown in FIGS. 11 to 13 will be described. In this case, the vibration amplification transmission mechanism is an amplification transmission mechanism 20 having a double lever action, and has a greater level of noise reduction function.

A first lever 12a is connected to a part of the inner wall of the housing jig 4, and a second lever 12b is connected to the first lever 12a from the opposite side so as to overlap with a predetermined gap vertically. Is brought into contact with the surface of the noise generating vibrating body 10, and the tip of the projection 14 a is brought into contact with the projection 14 b of the second lever 12 b, and the projection 13 b at the tip of the second lever 12 b is connected to the diaphragm 5. From below.

Therefore, in this case, the first lever 1
The vibration of the noise generating vibrating body 10 is double-amplified according to the respective lever ratios of the second lever 12a and the second lever 12b and transmitted to the diaphragm 5 of the resonator 3. That is, the diaphragm 5 is greatly vibrated by the double lever action of both levers 12a and 12b. For this reason, the level of the radiated sound generated from the resonator 3 is increased, and the radiated noise from the engine 1 is canceled by the large-level radiated sound, so that even with the small resonator 3, an efficient silencing effect can be obtained. is there.

The embodiment shown in FIGS. 14 and 15 includes a plurality of vibration amplification transmission mechanisms. That is, the two levers 12 are connected to the housing jig 4, and the vibration from the noise generating vibrating body 10 is input to the diaphragm 5 via the two levers 12.

By transmitting the vibration by the two levers 12 as described above, the vibration plate 5 can be vibrated more reliably, and the noise reduction performance can be further improved.

Next, an embodiment of FIG. 16 will be described. This embodiment is provided with a plurality of resonators 3a and 3b having different resonance frequencies so that a noise canceling function can be exhibited for noise in a plurality of frequency bands. It is.

In each of the above-described embodiments, the noise can be suppressed only in a single frequency band because of the relationship with the resonance frequency of the resonator 3. However, the resonators 3a and 3b having different resonance frequencies are used as described above. By providing, it is possible to demonstrate the silencing function in the corresponding frequency band,
The frequency band in which the noise level is desired to be reduced can be expanded according to the characteristics of the engine 1 and the like.

[0050]

According to the first aspect of the invention, the vibration of the noise source is directly and amplified and transmitted to the diaphragm of the resonator via the amplification transmission mechanism, and the vibration energy is greatly excited by the vibration energy. Therefore, the resonator emits a large level of radiated sound, and the radiated sound is inverted in phase at the resonance frequency, thereby canceling out generated noise and effectively reducing noise.

According to the second aspect, the vibration is expanded and transmitted by the lever action corresponding to the lever ratio, and the diaphragm can be efficiently vibrated.

According to the third and fourth aspects, the distance between the lower surface of the diaphragm and the noise vibration surface can be reduced, and the resonator can be efficiently arranged even in a narrow space.

According to the fifth aspect of the present invention, the lever ratio is further amplified by the plurality of levers, whereby the diaphragm is further vibrated even more, and even a small resonator can exhibit high noise reduction performance.

According to the sixth aspect of the present invention, since the vibration is transmitted by the plurality of levers, the vibration plate can be vibrated reliably, and a reliable noise reduction performance can be obtained.

According to the seventh aspect, the sound deadening function can be exhibited in a wide frequency band corresponding to the resonance frequency of the resonator.

According to the eighth aspect, the noise radiated from the engine can be effectively silenced by the function of the resonator disposed between the engine and the engine cover.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view of the same.

FIG. 3 is a perspective view of the resonator.

FIG. 4 is a sectional view of the same.

FIG. 5 is an explanatory view showing an operation state of the same.

FIG. 6 is a characteristic diagram showing the silencing characteristics of the same.

FIG. 7 is a perspective view showing a resonator according to a second embodiment.

FIG. 8 is a sectional view of the same.

FIG. 9 is a perspective view showing a third embodiment.

FIG. 10 is a sectional view of the same.

FIG. 11 is a perspective view of a resonator showing a fourth embodiment.

FIG. 12 is a sectional view of the same.

FIG. 13 is an explanatory diagram showing an operation state of the same.

FIG. 14 is a perspective view showing a fifth embodiment.

FIG. 15 is a sectional view of the same.

FIG. 16 is a perspective view showing a sixth embodiment.

FIG. 17 is a perspective view showing a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine 2 engine cover 3 resonator 4 housing jig 5 diaphragm 7 low rigidity member 8 opening 11 amplification transmission mechanism 12 lever 13 protrusion 14 protrusion

Claims (8)

[Claims] 1. A noise reduction device for reducing noise radiated from a vibration surface of a noise source, comprising: a resonator having a diaphragm and a low-rigidity member around the diaphragm; An amplifying transmission mechanism for amplifying and transmitting vibration from a surface. 2. An amplification transmission mechanism comprising: a lever having a base connected to a housing of a resonator; a projection contacting a diaphragm at a tip of the lever; and a vibration surface of a noise source at a base of the lever. 2. The muffler according to claim 1, further comprising: a protrusion that contacts the diaphragm, and transmits the input vibration to the diaphragm while expanding the input vibration according to the lever ratio. 3. The muffler according to claim 2, wherein a recess for accommodating a lever is formed in a part of the diaphragm, and a lower surface of the lever is formed substantially identical to a lower surface of the diaphragm excluding the recess. 4. The apparatus according to claim 1, wherein the lever is disposed in an internal space of the resonator, and a proximal end protrusion of the lever is configured to come into contact with a vibration surface of an external noise source through an opening formed in the diaphragm. Item 3. The muffler according to Item 2. 5. The amplification transmission mechanism according to claim 2, wherein the amplification transmission mechanism is configured by connecting at least two levers in series, and configured to at least double the transmission ratio of vibration according to each lever ratio. A silencer as described. 6. The muffler according to claim 2, wherein said amplification transmission mechanism is configured by arranging at least two levers in parallel. 7. The muffler according to claim 1, wherein at least two resonators having different resonance frequencies are provided as said resonator. 8. An engine cover for covering an upper surface of the engine with a predetermined gap, wherein the resonator is attached to a part of the engine cover, and an amplification transmission mechanism transmits vibration of the engine noise generating vibrator to the diaphragm. The muffler according to any one of claims 1 to 7, wherein the muffler is configured to: