JPH117287A - Muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler protecting a sound wave generator, a noise detector or a muffling deviation detector from acids, alkali, water, heat without injuring occurrence efficiency in a sound wave from the sound wave generator and injuring an S/N ratio of deviation level of a noise or a muffling. SOLUTION: Shield plates 35, 45, 55 having heat resistance, acid resistance, alkali resistance and waterproof are provided so as to divide internal space of a sound absorbing duct 31 from the noise detector 2, the muffling deviation detector 3 and a loud speaker 4. These shield plates are constituted also so that, though their rigidity is high, flexible rigidity is reduced by forming edge parts 35a, 45a, 55a on their peripheries. Thus, stable muffling control is realized without injuring these functions while protecting the noise detector 2, the muffling deviation detector 3 and the speaker 4 from exhaust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a muffler using active noise control (ANC) technology.

[0002]

FIG. 14 shows a conventional silencer. The noise detector 2 detects a noise P, the noise elimination deviation detector 3 detects a noise elimination deviation, and receives the output x of the noise detector 2 and the output e of the noise elimination deviation detector 3 to obtain the noise P and the magnitude. And a muffling signal generator 5 for forming a muffling signal y for generating a sound wave (muffling sound wave) having the same phase and opposite phase from the speaker 4 as a sound wave generator toward the sound absorbing duct 1. It is assumed that the noise source is located on the left side of the figure, not shown.

Referring to FIG. 15, output x of noise detector 2 is shown.
Is supplied to an adaptive filter (hereinafter abbreviated as ADF) 14 and a delay filter 13 via an amplifier 11 and an A / D converter 12. The output e of the silencing deviation detector 3 is supplied to a coefficient calculator 15 via an amplifier 16 and an A / D converter 17. The ADF 14 has N taps, the coefficients of which are updated by the output of the coefficient calculator 15. The delay filter 13 has an acoustic transfer characteristic corresponding to a path from the speaker 4 to the muffling deviation detector 3. That is, the coefficient of the delay filter 13 is determined in consideration of the time delay, and is measured or identified in advance. Further, the coefficient calculator 15 is an adaptive algorithm for sequentially calculating the optimum coefficient to be given to the ADF 14. The muffling signal generator 5 has a configuration using the above-described well-known ANC control technology.

[0004] With the above-described configuration of the conventional silencer, the level of the noise P emitted from the discharge end of the sound absorbing duct 1 is greatly reduced or made zero.
Further, the silencer having the above-described configuration is applied to a device that uses a blower, a generator, an engine, or the like as a noise source.

[0005]

However, in the structure of the conventional silencer described above, when the noise source is, for example, an automobile or a generator engine, the noise detector provided in the sound absorbing duct 1 as an exhaust pipe. 2. The silencing deviation detector 3 and the loudspeaker 4 are directly affected by an alkaline atmosphere, water, and heat of 600 ° C. or more due to the introduction of an acid such as sulfurous acid contained in exhaust gas (combustion gas) or ammonia for denitration. Therefore, their durability becomes a problem.

Accordingly, the present applicant has previously described a muffler in which a shielding member 25 made of polytetrafluoroethylene (PTFE), which is known by the trade name of Teflon, is provided near the front surface of the speaker 4 as shown in FIG. Proposed (Japanese Patent Application No. 9-50)
867). The peripheral edge of the shielding member 25 is sandwiched together with the speaker mounting member 23 and the dust seal 24 at the joint between the introduction portion 21 formed on the side wall of the sound absorbing duct 1 ′ and the casing 22 that houses the speaker 4. Is fixed by It is assumed that the introduction portion 21 and the casing 22 are connected by bolts or the like, not shown. Since the shielding member 25 is flexible and has acid resistance, alkali resistance, water resistance, and heat resistance, it vibrates almost integrally with the diaphragm (cone) of the speaker 4 and does not impair the acoustic characteristics of the speaker 4. , The deterioration of the speaker 4 due to the influence of water and heat. However,
The limit temperature of the heat resistance of the shielding member 25 is 260 ° C.
However, it cannot withstand the temperature of the exhaust gas of the engine, which is about 600 ° C. or more, and the speaker 4 cannot be reliably protected from the same harm.

On the other hand, there is mica as an alternative to Teflon, which has strong resistance to acids, alkalis, water and heat, but has poor rigidity (bending rigidity) and poor sound transmission. This causes a problem that the generation efficiency of sound waves from the speaker 4 is impaired. Further, if this is similarly provided on the front surface of the noise detector 2 and the noise elimination deviation detector 3, a problem arises that the S / N cannot be sufficiently obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and does not impair the efficiency of generating a sound wave from a sound wave generator, and does not impair the S / N of a noise or a noise reduction deviation level.
It is an object of the present invention to provide a silencer capable of protecting a sound wave generator, a noise detector, or a silencing deviation detector from acids, alkalis, water, and heat.

[0009]

The above objects are attained by a noise detector (2) for detecting noise from a noise source (for example, corresponding to a reference symbol P in the embodiment, the same applies hereinafter), and the noise (2). P), a sound absorbing duct (31), a silencing deviation detector (3) for detecting a silencing deviation, and outputs (x, e) of the noise detector (2) and the silencing deviation detector (3).
And a silencing signal (y) for generating a silencing signal (y) for generating a sound wave having the same magnitude as the noise (P) and having the opposite phase from the sound wave generator (4) toward the sound absorbing duct (31). A silencer comprising a generator (5);
One or both of the noise detector (2) and the silencing deviation detector (3) and / or the sound wave generator (4) and the internal space of the sound absorbing duct (31) are partitioned. A shielding plate (35, 45, 55, 48) made of a material having high rigidity and at least one of heat resistance, acid resistance, alkali resistance and water resistance. 55, 48) around the edge (35
a, 45a, 55a, 48a).

According to the first aspect of the present invention, the shielding plate (35, 4
5, 55, 48) around the edges (35a, 45a, 5
5a, 48a) are formed and the bending rigidity thereof is greatly reduced, so that the shielding plates (35, 45, 55, 48) are easily vibrated. Accordingly, the sound can be vibrated according to the sound wave (frequency) generated from the sound wave generator (4), so that the sound wave can be transmitted through the sound absorbing duct (31), and the sound wave generation efficiency is not impaired. By the same operation, the noise detector (2) or the noise reduction deviation detector (3) can detect the noise (P) or the noise reduction deviation level in the sound absorbing duct (31) without deteriorating the S / N. Can be. Furthermore, a shielding plate (35, 4
5, 55, 48) are made of a material having at least one of heat resistance, acid resistance, alkali resistance, and water resistance, so that the sound wave generator (4) and the noise detector are generated from the atmosphere in the sound absorbing duct (31). (2) Alternatively, the silencing deviation detector (3) can be protected and its durability can be increased.

[0011] Further, the above problems are a noise detector (2) for detecting noise (P) of a noise source, a sound absorbing duct (31) for introducing the noise (P), and a noise reduction deviation detection for detecting a noise reduction deviation. Receiving the outputs (x, e) of the noise detector (3), the noise detector (2), and the silencing deviation detector (3);
A muffling signal generating device (5) for forming a muffling signal (y) for causing a sound wave generator (4) to generate sound waves having the same magnitude and opposite phase from the sound wave generator (4) into the sound absorbing duct (31).
Wherein the surface of the diaphragm (60) and the surface of the edge (60a) of the sound wave generator (4) have at least one of heat resistance, acid resistance, alkali resistance and water resistance. The noise reduction device is characterized in that a film (70) made of a material having the following is formed.

[0012] The invention according to claim 3 of the present invention provides heat resistance,
The membrane (70) made of a material having at least one of acid resistance, alkali resistance and water resistance is applied to the surface of the diaphragm (60) of the sound wave generator (4) and its edge (60).
The vibration plate (60) is formed on the surface of (a).
The drive system of the inner sound wave generator (4) is connected to the sound absorbing duct (3
1) It protects from the inside atmosphere and increases its durability.

[0013] Further, the above problems are a noise detector (2) for detecting noise (P) of a noise source, a sound absorbing duct (31) for introducing the noise (P), and a noise reduction deviation detection for detecting a noise reduction deviation. Receiving the outputs (x, e) of the noise detector (3), the noise detector (2), and the silencing deviation detector (3);
A muffling signal generating device (5) for forming a muffling signal (y) for causing a sound wave generator (4) to generate sound waves having the same magnitude and opposite phase from the sound wave generator (4) into the sound absorbing duct (31).
And a protective plate made of a material having at least one of heat resistance, acid resistance, alkali resistance and water resistance on the front surface of the vibration plate (60) of the sound wave generator (4). 71), wherein a space between the diaphragm (60) and the protective plate (71) is filled with a foam (72).

According to a fifth aspect of the present invention, a material having at least one of heat resistance, acid resistance, alkali resistance and water resistance is provided on the front surface of the vibration plate (60) of the sound wave generator (4). The protective plate (71) is provided, and the space between the vibrating plate (60) and the protective plate (71) is filled with a foam (72) so that the protective plate (71) is moved to the vibrating plate (60). It is made to vibrate integrally. Thereby, the same effect as the third aspect can be obtained.

[0015] Further, the above problems are a noise detector (2) for detecting a noise (P) of a noise source, a sound absorbing duct (31) for introducing the noise (P), and a noise reduction deviation detection for detecting a noise reduction deviation. Receiving the outputs (x, e) of the noise detector (3), the noise detector (2), and the silencing deviation detector (3);
A muffling signal generating device (5) for forming a muffling signal (y) for causing a sound wave generator (4) to generate sound waves having the same magnitude and opposite phase from the sound wave generator (4) into the sound absorbing duct (31).
Wherein the noise detector (2) and / or the noise reduction deviation detector (3);
And / or a first coating (101) made of a heat resistant but not completely airtight material so as to separate the sound wave generator (4) from the internal space of the sound absorbing duct (31).
And a second film (102) made of a material having no heat resistance but airtightness is provided in order from the sound absorbing duct (31) side.

That is, the invention according to claim 8 of the present invention provides:
The first film (101) and the second film (102) protect the noise detector (2), the silencing deviation detector (3) or the sound wave generator (4).

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A silencer according to each embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall view of a silencer according to a first embodiment of the present invention. The noise detector 2 includes a sound absorbing duct 3
It is provided inside a casing 34 integrally attached via a gasket 33 to an introduction portion 32 provided on one side wall, and is supported by an elastic support member 36 made of rubber, for example. Further, between the introduction part 32 and the gasket 33, a shielding plate 3 having an edge portion 35a formed around the noise detector 2 and the inner space of the sound absorbing duct 31 so as to partition the noise detector 2.
5 are provided. In addition, the introduction part 32 and the gasket 3
3, and the gasket 33 and the casing 34 are connected by bolts or the like, not shown.

The silencing deviation detector 3 also has an introduction section 5
2 is provided inside a casing 54 integrally attached via a gasket 53, and is supported by an elastic support member 56 made of, for example, rubber. In addition, the introduction unit 52
Between the gasket 53 and the gasket 53, there is provided a shielding plate 55 having an edge portion 55a formed therearound so as to partition the silencing deviation detector 3 and the internal space of the sound absorbing duct 31.

Receiving the output x of the noise detector 2 and the output e of the silencing deviation detector 3, a silencing signal y for forming a muffling sound wave (sound having the same magnitude and opposite phase as the noise P) is converted into a sound wave It is supplied to a speaker 4 as a generator. The speaker 4 includes a casing 44 integrally attached to the introduction section 42 via a gasket 43 and a speaker attachment member 46.
And is attached to the attachment member 46. Between the introduction portion 42 and the gasket 43, a shielding plate 45 having an edge portion 45a formed therearound is provided so as to partition the speaker 4 and the internal space of the sound absorbing duct 31.

In this embodiment, these shielding plates 35, 4
Nos. 5 and 55 have high rigidity and are made of a metal having excellent environmental resistance, such as stainless steel, titanium, gold or silver, which is a material having all of heat resistance, acid resistance, alkali resistance and water resistance. . The edge portions 35a, 45a and 55a of the shielding plates 35, 45 and 55 are integrally formed by press molding. Further, the shielding plates 35, 45 and 55 are formed of a soft material such as aluminum, and a material having at least one of heat resistance, acid resistance, alkali resistance and water resistance as described above is deposited or plated on the surface thereof. It may be made to adhere and join by such as.

The first embodiment of the present invention is configured as described above. Next, this operation will be described.

A noise P generated from a noise source (not shown) (for example, an automobile engine) flows through the sound absorbing duct 31 rightward in the figure. The noise detector 2 that detects the noise P
The noise P guided to the introduction unit 32 is detected via the shielding plate 35. At this time, the shielding plate 35 vibrates from the edge portion 35 a as a base point in accordance with the magnitude (amplitude) and frequency of the noise P, and transmits the noise P toward the noise detector 2. Further, since the noise detector 2 can be protected from the exhaust gas flowing in the sound absorbing duct 31 together with the noise P, its durability can be improved. At this time, since the shielding plate 35 has all of heat resistance, acid resistance, alkali resistance and water resistance, it is not affected by the exhaust gas. On the other hand, the shielding plate 55 provided on the side of the noise reduction deviation detector 3 also performs the same operation, and can protect the noise reduction deviation detector 3 from exhaust gas flowing in the sound absorption duct 31.

Thus, the noise detector 2 and the silencing deviation detector 3 can detect the noise P and the silencing deviation level, respectively, without deteriorating the S / N. The noise detector 2 and the silencing deviation detector 3 are each provided with an elastic support member 36.
And 56, the effect of the vibration propagating from the noise source via the sound absorbing duct 31 is reduced.

Since the muffling signal generator 5 is the same as the conventional muffling signal generator described with reference to FIG. 10, its detailed description is omitted, but the output x of the noise detector 2 is omitted.
And the output e of the silencing deviation detector 3 to form a silencing signal y. The silencing signal y is supplied to the drive unit of the speaker 4, and generates a silencing sound wave having the same magnitude as the noise P and having the opposite phase toward the sound absorbing duct 31. At this time, the shielding plate 4
5 vibrates with its edge 45a as a starting point, and introduces sound-absorbing sound waves into the sound-absorbing duct 31. With this, the known AN
C control is performed.

Further, since the shielding member 45 is provided so as to partition the internal space of the sound absorbing duct 31 and the speaker 4, the speaker 4 can be protected from high-temperature exhaust gas containing acid, alkali and water. Thus, the long-term durability of the speaker 4 can be ensured. Furthermore, even though the shielding plate 45 is made of a material having high rigidity, it can be easily vibrated by the edge portion 45a formed around the shielding plate 45, so that the generation efficiency of sound waves from the speaker 4 is not impaired.

Therefore, according to the present embodiment, the noise detector 2, the silencing deviation detector 3, and the speaker 4 are reliably protected from high-temperature exhaust gas containing acid, alkali and water to enhance their durability. In addition, the noise detector 2 and the silencing deviation detector 3 can detect a sound without deteriorating the S / N. Further, regarding the speaker 4, the AN can be effectively performed without impairing the sound wave generation efficiency.
C control can be performed.

FIG. 2 shows a second embodiment of the present invention. In the present embodiment, the shielding plate 48 provided so as to partition the internal space of the sound absorbing duct 31 and the speaker 4 is formed in a dome shape projecting toward the sound absorbing duct 31 in the first embodiment described above. Is different from the form.

That is, in the first embodiment,
The vibration of the shielding plate 45 is performed by elastically deforming the plane portion at the center thereof. However, in the high frequency range, secondary vibration is generated in the plane portion and different types of sound waves are generated. Become. Therefore, it may be difficult to ensure effective ANC control in a high frequency range.

Therefore, in the present embodiment, the central portion of the shielding plate 48 is formed in a dome shape, so that the vibration of the shielding plate 48 is limited to the vibration starting from the edge portion 48a without allowing elastic deformation of the central portion. In the high frequency range, the vibration of the center of the dome is completely reduced by the piston motion.
By obtaining the secondary vibration, acoustic characteristics in a high frequency range are ensured. Therefore, according to the present embodiment, characteristics superior to those of the first embodiment can be obtained, especially in a high frequency range. Although not shown, the dome-shaped shielding plate 48 may be provided on the noise detector 2 side or the silencing deviation detector 3 side.

FIG. 3 shows a third embodiment of the present invention. In the present embodiment, the noise detector 2 and the sound absorbing duct 3
The first film 101 and the second film 102 are provided in order from the sound absorbing duct 31 side so as to divide the internal space 1 from the inside. The same reference numerals are given to the portions corresponding to FIG. 1, and the detailed description thereof will be omitted.

The first film 101 has heat resistance but does not have complete airtightness, such as glass cloth, carbon cloth, silica cloth, and ceramic paper. Further, a metal net having these materials interposed therebetween may be used. On the other hand, the second film 102 is made of a polymer material such as a fluororesin (PTFE, FEP, ETFE, PFA, etc.), polyimide, polypropylene, polyethylene terephthalate, etc. as a material having no heat resistance but having complete airtightness. ing. That is, the first film 101 protects the noise detector 2 from high temperatures, and the second film 1
02 protects the noise detector 2 from acid, alkali and water. Moreover, since the first film 101 and the second film 102 are flexible, the sound transmission is good, so that the noise detector 2 can detect the noise P without deteriorating the S / N.

Although not shown, these first coatings 101
Even if the second film 102 is provided on the front surface of the silencing deviation detector 3 or the speaker 4, it can be protected from heat, acid, alkali and water. Especially in the speaker 4,
Sound absorbing duct 3 without damaging its sound characteristics
1 can be supplied.

FIG. 4 shows a fourth embodiment of the present invention. Parts corresponding to those in FIG. 3 are denoted by the same reference numerals. In this embodiment, a first film 101 and a second film 102 made of the same material as those of the above-described third embodiment are used.
However, cooling fins 133a are provided on the outer peripheral surface of the tubular member 133 that supports the first coating 101 and the second coating 102, so as to promote the heat radiation action of the tubular member 133. That is, the heat of the exhaust gas of several hundred degrees Celsius in the sound absorbing duct 131 is transmitted to the noise detector 2 via the tubular member 133 and the casing 34 to prevent the noise detector 2 from being damaged. I have. In addition, if necessary, the cooling fan 12 that blows toward the tubular member 133 in the vicinity of the tubular member 133.
By providing 0, the cooling effect can be enhanced. Thus, the second film 10 having insufficient heat resistance is used.
By setting the temperature in the vicinity of the noise detector 2 or the noise detector 2 to 80 ° C. or less, it is not necessary to consider these heat resistances. In addition, if the same configuration is applied not only to the noise detector 2 but also to the speaker 4, the speaker 4 can be configured by very inexpensive general parts without using special and expensive parts or materials requiring heat resistance. (However, in this case, the first
The sound receiving area of the film 101 is configured to be equal to the sound receiving area of the second film 102).

In this embodiment, as shown in the figure,
The sound receiving area of the first coating 101 is limited by the introduction portion 132 of the sound absorbing duct 131 and the heat insulating material 114, and the second coating 10
2 is set smaller than the sound receiving area. More specifically, the sound receiving area of the first coating 101 is determined by
And the area of the hole 132a formed in the center of the heat insulating material 114. In this way, the loud noise flowing through the sound absorbing duct 131 is reduced to the first level.
The so-called acoustic attenuator (at
By performing the function as a tenor, for example, even a noise detector having a sound reception limit volume of 80 dB can detect a large volume noise exceeding 120 dB without saturating the noise detector.

Further, in the present embodiment, the first film 101
In order to make the movement of the second coating 102 smooth,
Introducing section 132 of sound absorbing duct 131 supporting film 101
And the end of the heat insulating material 114, the end of the tubular member 133 supporting the second coating 102, and the end of the anti-vibration rubber 115 for suppressing the transmission of vibration to the casing 34. And the S / N of the noise detector 2
To increase. The noise detector 2 is supported by an elastic support member 116 made of, for example, silicone gel.

FIG. 5 shows a speaker 4A according to a fifth embodiment of the present invention. The general configuration of the speaker will be described with reference to FIG. 5. A diaphragm 60 made of paper or aluminum is provided inside a frame 63 having a plurality of openings 63a formed on the side surfaces thereof.
a is fixed to the edge of the frame 63. The driving unit will be described. A pole fixed integrally with a back plate 66 is mounted on a cylindrical bobbin 64 which is concentrically fixed to a lower end of a diaphragm 60 and has a voice coil 62 wound on a side periphery. The piece 65 is loosely fitted. A permanent magnet 68 is fixed between the top plate 67 and the back plate 66 fixed to the bottom of the frame 63 at a predetermined interval concentrically with the pole piece 65. The diaphragm 60 vibrates in the vertical direction in the figure by receiving an alternating magnetic attraction force generated by applying an alternating current to the voice coil 62. At this time, while the lower end of the diaphragm 60 is supported by a spider 61 made of aramid fiber, carbon fiber, glass fiber, or the like disposed between the inner surface of the frame 63 and the bobbin 64, the damper action of the spider 61 is performed. Upon receiving the vibration, the diaphragm 60 vibrates.

Therefore, in the present embodiment, as shown, the surface of the diaphragm 60 of the speaker 4A and its edge 60a
Further, a protective film 70 made of stainless steel, titanium, gold or silver as a material having heat resistance, acid resistance, alkali resistance and water resistance is formed. This is because the above-described material is formed into a sheet shape and the surface of the diaphragm 60 and the edge portion 60 are formed.
a. Thereby, the speaker 4A
The driving system such as the vibration plate 60 and the voice coil 62 therein can be protected from exhaust gas, and the durability thereof can be improved.

FIG. 6 shows a speaker 4B according to a sixth embodiment of the present invention. Parts corresponding to those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, a protective plate 71 made of stainless steel, titanium, gold, or silver as a material having all of heat resistance, acid resistance, alkali resistance, and water resistance is provided on the front surface of diaphragm 60. The vibration plate 60 and the drive system therein are protected from exhaust gas. In addition, in order to vibrate the vibration plate 60 and the protection plate 71 integrally, a foam 72 is filled in a space defined between the vibration plate 60 and the protection plate 71. The foaming adhesive that is used is used. Thereby, the protection plate 71 can be vibrated by being integrated with the diaphragm 60,
Since the space between them is filled with a low-density foam, the vibration of the diaphragm 60 is not affected. That is, the speaker can be protected from exhaust gas without impairing the generation efficiency of sound waves. Further, the configuration can be simplified as compared with the above-described first embodiment (the configuration on the speaker 4 side).

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited to these, and various modifications can be made based on the technical concept of the present invention.

For example, in the above-described first embodiment, the shield plates 35, 45 and 55 are provided for all of the noise detector 2, the silencing deviation detector 3 and the loudspeaker 4. Only one may be provided. Further, the shielding plates 35, 45 and 55 do not need to be formed of a material having all of heat resistance, acid resistance, alkali resistance and water resistance unlike the above-described embodiments, and the sound absorbing duct 31 depends on the type of the noise source. Since the atmosphere inside, that is, the type of exhaust gas changes, the shielding plate may be formed of at least one of the above-mentioned materials having resistance in accordance with these. This is the same for the first film 101 and the second film 102 in the third and fourth embodiments.

In the first embodiment, the edges 35a, 45a and 55 of the shielding plates 35, 45 and 55 are used.
a to a corrugated edge 76 as shown in FIG.
However, of course, the present invention is not limited to this, and other known shapes such as a roll shape 75 shown in FIG. 7A or FIG.
May be formed by a reverse roll shape 77 shown in FIG. Note that the corrugated edge 76 in FIG. 7B can increase the stroke length, and is thus effective for a speaker that emits a relatively large sound pressure.

Similarly, the edge portion 48a of the dome-shaped shielding plate 48 in the above-described second embodiment is also formed in a corrugation shape. However, as shown in FIGS. 8 and 9, a so-called tangential edge is formed. A dome-shaped shielding plate 80 having a portion 81 may be used. This is noise detector 2
This is effective for the shield plate of the noise reduction deviation detector 3. In addition, it is of course possible to form an edge portion having the shape shown in FIGS. 7A and 7C.

In the first and second embodiments described above, the edge is formed integrally with the shielding plate. However, the edge may be formed as a separate material. In this case, it is necessary to form the edge portion with a material having the same characteristics as the material forming the shielding plate. However, the same effect can be obtained by bonding these with an adhesive or the like to integrate them. it can.

In the third and fourth embodiments described above, the structure in which the first film 101 and the second film 102 are provided has been described. However, the structure may be as shown in FIG. 10 or FIG. In the figure, portions corresponding to FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 10 shows the first film 101 and the second film 10.
The space A inside the tubular member 133 divided by the space B and the space B in which the noise detector 2 is arranged and the sound absorbing duct 131
Communication means for enabling communication with the internal space C.
That is, the communication hole 85 is provided in the introduction portion 132 of the sound absorbing duct 131, and the tubular member 133 and the casing 3
4 are provided with communication holes 86 and 87, and these are connected by a flexible tube 88. As a result, the spaces A, B and C can communicate with each other and have the same pressure. Therefore, the first and second coatings 101, 102
Thus, it is possible to prevent the vibration due to the application of the tension by the action of the static pressure and the sound transmission characteristics from being impaired. In addition, breakage of the films 101 and 102 due to excessive static pressure is also prevented. In addition, the first film 101 is supported by a peripheral portion thereof being bonded to a bottom surface of the introduction portion 132.

At this time, if the distance L between the first coating 101 and the second coating 102 is determined so that the internal air column resonance frequency is higher than the upper limit of the silencing band on the high frequency side, the inside of the tubular member 133 can be determined. Can be prevented, and noise can be detected without deteriorating S / N.

On the other hand, in FIG. 11, the communication between the space A and the space B is made through the communication hole 89 provided in the bottom 133b of the tubular member 133, but the communication between the space A and the space C is made of silica. It is performed through a gas-permeable first film 101 'made of heat-resistant fiber or the like. That is,
The first film 101 ′ transmits noise by its vibration and also transmits air. Thereby, the same effect as described above can be obtained. In this configuration example, the second film (made of PTFE (polytetrafluoroethylene)) 10
2, the sound receiving area is set smaller than the sound receiving area of the first film 101 '. This eliminates the influence of the vibration of the tubular member 133 itself, and makes the noise detector smaller than the fourth embodiment. 2, the noise can be faithfully transmitted, and the S / N can be improved. Note that the second coating 102 is supported by bonding its peripheral edge to the bottom 133 b of the tubular member 133.

As shown in FIG. 12, as a communication means for connecting the space A and the space B, as shown in FIG. 12, the upper surface (space A side) of the communication hole 89 formed in the bottom portion 133b of the tubular member 133 allows only air to pass therethrough, May be covered with a ventilation material 93 that does not transmit light. The constituent material of the ventilation material 93 is, for example, breathable leather (breathable leather).
her) and a porous PTFE film. FIG.
As shown in FIG. 3, it is also possible to provide a communication hole 102a in the second film (made of PTFE) 102 and to attach the communication hole 102a so as to cover the communication hole 102a with the ventilation material 93. In this case, it is advantageous in that the ventilation material 93 performs a damping action to prevent higher-order vibration of the film 102 and further improve the S / N.

Next, in the above-described fifth embodiment, the protective film 70 is formed in a sheet shape and is adhered to the surface of the diaphragm 60 and the edge portion 60a thereof. The entire diaphragm 60 may be made of aluminum, and a metal thin film of stainless steel, titanium, gold, or silver may be formed by a vacuum deposition method, plating, or the like. With this, the same effect as described above can be obtained.

In the sixth embodiment described above, the foam 72 is formed of a foaming adhesive. However, the present invention is not limited to this.
Other foams such as sponge and urethane foam may be used.

[0053]

As described above, according to the sound deadening device of the present invention, the sound generation efficiency of the sound wave generator is not impaired, and the S / N of the noise or the sound deadening deviation level is not impaired. While protecting the sound wave generator, the noise detector, or the silencing deviation detector from acids, alkalis, water, and heat, stable silencing control can be ensured without impairing these functions.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing the vicinity of a sound wave generator according to a second embodiment of the present invention.

FIG. 3 is an enlarged sectional view near a noise detector showing a third embodiment of the present invention.

FIG. 4 is an enlarged sectional view showing the vicinity of a noise detector according to a fourth embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a sound wave generator according to a fifth embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a sound wave generator according to a sixth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a modified example of the shape of the edge of the shielding plate according to the present invention, wherein A shows a roll shape, B shows a corrugation shape, and C shows an inverted roll shape.

FIG. 8 is a plan view showing a part of an edge of a shielding plate according to a second embodiment of the present invention.

FIG. 9 is a sectional side view of the same.

FIG. 10 is a side sectional view showing a modification of the fourth embodiment of the present invention.

FIG. 11 is a side sectional view showing another modification.

FIG. 12 is a partial side sectional view showing a modification of the configuration of the communication means according to the present invention.

FIG. 13 is a partial side sectional view showing another modification.

FIG. 14 is a side sectional view showing a conventional silencer.

FIG. 15 is a circuit diagram of a muffling signal generator.

FIG. 16 is a partial side sectional view showing a sound wave generator in another conventional silencer.

[Explanation of symbols]

 Reference Signs List 2 noise detector 3 noise reduction deviation detector 4 speaker 5 noise reduction signal generator 31 sound absorption duct 35 shielding plate 35a edge portion 45 shielding plate 45a edge portion 55 shielding plate 55a edge portion 70 protective film 71 protective plate 72 foam 85 communication hole 86 Communication hole 87 Communication hole 89 Communication hole 93 Vent material 101 First coating 102 Second coating 120 Cooling fan 133 Tubular member 133a Cooling fin

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ Identification code FI H03H 17/00 601 H03H 17/02 633Z 17/02 633 21/00 21/00 G10K 11/16 B

Claims (12)

[Claims] A noise detector for detecting noise of a noise source;
The noise-absorbing duct for introducing the noise, a silencing deviation detector for detecting a silencing deviation, receiving the output of the noise detector and the silencing deviation detector, receiving a sound equal in magnitude to the noise, and generating a sound wave of the opposite phase. A muffling signal generator that forms a muffling signal for generating from a sound wave generator toward the inside of the sound absorbing duct, wherein one or both of the noise detector and the muffling deviation detector, and And / or a shield plate made of a material having high rigidity and having at least one of heat resistance, acid resistance, alkali resistance, and water resistance so as to partition the sound wave generator and the internal space of the sound absorbing duct. A sound deadening device, wherein an edge is formed around the shielding plate. 2. The muffler according to claim 1, wherein the shielding plate has a dome shape. 3. A noise detector for detecting noise of a noise source;
The noise-absorbing duct for introducing the noise, a silencing deviation detector for detecting a silencing deviation, receiving the output of the noise detector and the silencing deviation detector, receiving a sound equal in magnitude to the noise, and generating a sound wave of the opposite phase. A muffling signal generating device for forming a muffling signal for generating from the sound wave generator toward the inside of the sound absorbing duct, wherein the surface of the diaphragm of the sound wave generator and the surface of its edge have heat resistance, A muffler characterized by forming a film made of a material having at least one of acid resistance, alkali resistance and water resistance. 4. The muffler according to claim 3, wherein the film is formed by a vacuum deposition method. 5. A noise detector for detecting noise of a noise source,
The noise-absorbing duct for introducing the noise, a silencing deviation detector for detecting a silencing deviation, receiving the output of the noise detector and the silencing deviation detector, receiving a sound equal in magnitude to the noise, and generating a sound wave of the opposite phase. A muffling signal generator for forming a muffling signal for generation from the sound wave generator toward the inside of the sound absorbing duct, wherein the sound wave generator has a heat-resistant, acid-resistant, and alkali-resistant surface in front of a diaphragm. And a protection plate made of a material having at least one of water resistance, and a space between the vibration plate and the protection plate is filled with a foam. 6. The muffler according to claim 5, wherein the foam is made of a foamable adhesive. 7. The silencer according to claim 1, wherein the material having heat resistance, acid resistance, alkali resistance and water resistance is stainless steel, titanium, gold or silver. apparatus. 8. A noise detector for detecting noise of a noise source,
The noise-absorbing duct for introducing the noise, a silencing deviation detector for detecting a silencing deviation, receiving the output of the noise detector and the silencing deviation detector, receiving a sound equal in magnitude to the noise, and generating a sound wave of the opposite phase. A muffling signal generator that forms a muffling signal for generating from a sound wave generator toward the inside of the sound absorbing duct, wherein one or both of the noise detector and the muffling deviation detector, and And / or a first coating made of a material having heat resistance but not completely airtight so as to partition the sound wave generator and the internal space of the sound absorbing duct, and a material having no heat resistance but airtightness And a second coating formed from the sound absorbing duct side. 9. The muffler according to claim 8, wherein cooling fins are provided on an outer peripheral surface of the tubular member supporting the first coating and the second coating. 10. The muffler according to claim 9, wherein a cooling fan is arranged near the tubular member. 11. The muffler according to claim 8, wherein one of the first coating and the second coating has a smaller sound receiving area than the other. . 12. The muffler according to claim 8, further comprising communication means for mutually communicating each space defined by the first film and the second film. .