JP3138373B2 - Active silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active silencer in which an exhaust pipe through which a high-temperature exhaust gas flows is provided with a silencing speaker for generating a sound having a phase opposite to the noise in the exhaust pipe.

[0002]

2. Description of the Related Art An active noise reduction device picks up noise with a microphone and generates a sound having an opposite phase to the noise detected by the microphone to muffle the noise.
Although the invention was invented in the 934's, the frequency band of the actual noise was wide, and it was difficult to generate a sound in the opposite phase to the noise in such a wide band to suppress the noise. However, due to recent advances in acoustic engineering, active noise reduction has been attracting attention due to the DSP (Digital Signal Processor) technology, in particular, because it has a greater noise reduction effect than passive noise reduction using conventional sound absorbing materials.

In order to reduce the noise in the exhaust pipe by using this active noise reduction, a microphone is attached to the exhaust pipe, a speaker for noise reduction is attached to the exhaust pipe, and the noise detected from the microphone is DSP-processed to perform the opposite phase. The sound is emitted from the muffling speaker.

[0004]

Generally, a loudspeaker is mainly composed of a cone for mainly emitting sound, a voice coil and a magnet for vibrating the cone, and the cone is particularly made of paper.

[0005] When high-temperature exhaust gas is supplied to the exhaust pipe on which the above-mentioned active noise reduction is performed, the loudspeaker cone is deteriorated or burned out by radiant heat.

Accordingly, an object of the present invention is to solve the above problems and to provide an active silencer capable of silencing noise even when the exhaust gas flowing in the exhaust pipe is at a high temperature.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an active pipe provided with a muffling speaker for generating a sound having a phase opposite to the noise in the exhaust pipe through which a high-temperature exhaust gas flows. In the silencer, a substantially L-shaped connecting pipe is connected to a side wall of the exhaust pipe, and a bent portion of the connecting pipe is provided.
A large number of small holes are provided, and a chamber covering the large number of small holes is provided.
Only, the end of the connecting tube, the enclosure so as to cover the speaker digested sound is attached to mute the speaker provided, cooling means for supplying cooling gas to protect the mute speaker from a high temperature to the chamber It is provided.

[0008]

[0009]

The present invention relates to an active silencer in which an exhaust pipe through which a high-temperature exhaust gas flows is provided with a silencing speaker for generating a sound having a phase opposite to the noise in the exhaust pipe, wherein a connecting pipe is connected to a side wall of the exhaust pipe. At the end of the connecting pipe, a sound deadening speaker is attached and an enclosure is provided so as to cover the sound deadening speaker, and the enclosure is provided with cooling means for supplying a cooling gas for protecting the sound deadening speaker from high temperatures, and A bypass flow path to the connecting pipe is provided so that the cooling gas is discharged from the enclosure to the connecting pipe.

According to the present invention, in addition to the above configuration, the muffling speaker further includes a diaphragm for generating a sound having an opposite phase, and a hydraulic vibrator for driving the diaphragm.

[0012]

According to the above construction, since the cooling means supplies the cooling gas to the front or the periphery of the silencing speaker, even if high-temperature exhaust gas flows in the exhaust pipe, the heat reaches the silencing speaker. Protected from high temperatures. With this,
Since the noise elimination speaker generates a sound having a phase opposite to that of the noise, the noise and the sound from the noise elimination speaker cancel each other out and are eliminated.

Further, since the connecting pipe is formed substantially in an L-shape, the radiant heat from the exhaust pipe hits the bent portion of the connecting pipe once and then goes to the speaker. Are further protected from high temperatures.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an active silencer on which the present invention is based .

In FIG. 1, reference numeral 1 denotes an exhaust pipe serving as a flow path 1a of exhaust gas flowing from a refuse incinerator, a boiler, or the like as indicated by an arrow. A detection microphone 2 for detecting noise is provided in the exhaust pipe 1.
A connecting pipe 3 is mounted on a side wall on the downstream side of the detection microphone 2, and an error microphone 4 is mounted downstream of the connecting pipe 3.

At the end of the connecting pipe 3, a muffling speaker 5 is mounted, and the speaker 5 is provided with an enclosure 6 so as to cover the speaker 5.

The noise picked up by the detection microphone 2 is input to the controller 7, which forms a signal having a sound opposite in phase to the noise and drives the speaker 5 so that the speaker 5 generates a sound opposite in phase. Has become.

The controller 7 detects the sound in the exhaust pipe 1 with the error microphone 4 and adjusts the volume and phase of the sound generated from the speaker 5 to mute the noise.

On the other hand, the connecting pipe 3 is provided with a gas inlet 8 as cooling means, for example, outside air (normal temperature).
Is to be injected. The injected air is discharged into the exhaust pipe 1 via the connecting pipe 3.

In the embodiment shown in FIG.
Although air is used as the gas injected from the, gas that does not generate heat even at a high temperature, such as nitrogen gas or carbon dioxide gas, may be used.

Next, the operation of the active silencer shown in FIG. 1 will be described.

When air is injected from the gas inlet 8, the air is discharged into the exhaust pipe 1 via the connecting pipe 3. At this time, even if the high-temperature exhaust gas passes through the exhaust pipe 1, the front surface (upper side in the figure) of the speaker 5 is supplied with air at normal temperature (lower than the exhaust gas), so that the front surface of the speaker 5 has a low temperature. As a result, the speaker 5 is protected from high temperatures. Noise in the exhaust pipe 1 is detected by the detection microphone 2 and sent to the controller 7. The controller 7 sends a signal having a phase opposite to that of the noise obtained by the detection microphone 2 to the speaker 5, and detects a sound in the exhaust pipe 1 by the error microphone 4 so that the noise in the exhaust pipe 1 is muted. , The volume and phase of the speaker 5 are controlled. As a result, noise in the exhaust pipe 1 is reduced.

According to the active silencer described above, the connecting pipe 3 is connected to the side wall of the exhaust pipe 1 and the connecting pipe 3
The speaker 5 is attached to the end of the
The enclosure 6 is provided so as to cover the loudspeaker, and the gas inlet 8 for supplying air for protecting the loudspeaker 5 from high temperature is provided in the connecting pipe 3, so that the exhaust gas flowing through the exhaust pipe 1 has a high temperature. Thus, an active noise reduction device capable of reducing noise can be realized.

Although the present active silencer has been described with a single gas inlet 8, the present invention is not limited to this. A plurality of gas inlets 8 may be provided around the front surface of the speaker 5.
In addition, although the description has been given of the case where the temperature of the air is normal temperature, it goes without saying that air cooled by an air conditioner or the like may be injected.

FIG. 2 is a diagram showing another activite on which the present invention is based .
It is a schematic diagram of a noise reduction device . However, for simplicity of description, a controller, a detection microphone, an error microphone, and the like are omitted.

The difference from the active silencer shown in FIG. 1 is that the connecting pipe is formed in a substantially L-shape.

When air is injected from a gas injection port 8 formed on the side wall of the connecting pipe 10 formed in a substantially L-shape on the speaker 5 side, the injected air passes through the connecting pipe 10 and exhaust pipe 1. It is designed to be discharged inside. For this reason, since the radiant heat of the exhaust gas hits the bent portion of the connecting pipe 10 and is reflected and travels toward the speaker 5, the radiant heat of the high-temperature exhaust gas passing through the exhaust pipe 1 does not directly hit the speaker 5. In addition, the vicinity of the front surface of the speaker 5 is cooled by the air from the gas inlet 8, so that the speaker 5 is further protected from high temperatures. Therefore, exhaust pipe 1
It is possible to realize an active silencer capable of silencing noise even when exhaust gas flowing through the inside is high temperature.

Although the gas inlet 8 is formed in the vicinity of the speaker 5 of the connecting pipe 10 in the drawing, the invention is not limited to this. The gas inlet 8 is formed in the vicinity of the exhaust pipe 1 or in the bent portion 11. Is also good.

FIG. 3A shows an active silencer of the present invention.
Is a schematic diagram of one embodiment of FIG. 3 (b) is an external view of the small hole is viewed from a direction along the plane of the circle C in FIG. 3 (a).

The difference from the active silencer shown in FIG. 2 is that the compressed gas is discharged into the exhaust pipe through a number of small holes provided in the bent portion of the connecting pipe.

As shown in FIGS. 3 (a) and 3 (b), the bent portion 11 of the connecting pipe 10 formed substantially in an L-shape.
Are formed with a large number of small holes (40, but not limited in the figure). A chamber 13 is provided in the bent portion 11 of the connecting pipe 10 so as to cover these small holes 12, and a pump 14 is provided in the chamber 13. The pump 14 compresses external air and injects compressed air into the chamber 13. The compressed air is injected into the connecting pipe 10 as a uniform flow through the small holes 12 and then is forcibly discharged into the exhaust pipe 1. Therefore, the high-temperature gas in the exhaust pipe 1 is prevented from being transmitted to the speaker 5 by convection, and the speaker 5 is protected from high temperature.
Of course, as described above, the noise in the exhaust pipe 1
Is canceled out by the sound generated from the sound. Therefore, it is possible to realize an active silencer capable of silencing noise even when the exhaust gas flowing in the exhaust pipe 1 has a high temperature.

FIG. 4 is a schematic view of another embodiment of the present invention.

The difference from the above-described embodiment is that the cooling gas is discharged from the enclosure to the connecting pipe.

As shown in FIG. 4, a connecting pipe 15 is connected to a side wall of the exhaust pipe 1, a speaker 5 is attached to an end of the connecting pipe 15, and an enclosure 16 is attached to the speaker 5 so as to cover the speaker 5. Is provided. The enclosure 16 is provided with a gas inlet 17 for supplying air for protecting the speaker 5 from high temperatures, and a bypass passage 18 is provided between the enclosure 16 and the connection pipe 15.

When the outside air is injected into the enclosure 16 from the gas inlet 17, the rear surface (the lower side in the figure) of the speaker 5 is cooled, and then the air flows into the connection pipe 15 through the bypass flow path 18. After being injected, the front surface of the speaker 5 is cooled and discharged into the exhaust pipe 1. That is, since the front and rear surfaces of the speaker 5 are cooled, the heat of the high-temperature gas in the exhaust pipe 1 is also blocked by the air from the bypass passage 18 toward the speaker 5. Is not transmitted. Therefore, it is possible to realize an active silencer capable of silencing noise even when the exhaust gas flowing in the exhaust pipe 1 has a high temperature.

FIG. 5 is a schematic view of another embodiment of the present invention.

The difference from the embodiment shown in FIG. 4 is that a hydraulic speaker is used as the speaker.

Referring to FIG. 5, the hydraulic speaker comprises a diaphragm 19 for generating a sound having a phase opposite to that of noise, and a hydraulic exciter 20 for driving the diaphragm 19. Diaphragm 19
Is mounted on a piston rod 21 of the hydraulic exciter 20 so that the piston rod 21 can reciprocate in its axial direction. Paper is not used for the diaphragm 19, but a thin plate made of a light metal such as aluminum is used. The hydraulic exciter 20 has a servo valve 22
Is connected. The servo valve 22 is opened and closed by an electric signal from the controller 7 to control the amount of oil supplied to and discharged from the hydraulic exciter 20. That is,
The hydraulic exciter 20 operates in response to a signal from the controller 7 to the servo valve 22, the piston rod 21 vibrates in the axial direction, and the diaphragm 19 also vibrates with this to generate sound. I have.

A connecting pipe 15 is connected to the side wall of the exhaust pipe 1, and an enclosure 16 is connected to an end of the connecting pipe 15. A hydraulic exciter 20 is mounted in the enclosure 16. The diaphragm 19 attached to the piston rod 21 of the hydraulic exciter 20 is located in the connecting pipe 15. Enclosure 16 and connecting pipe 1
A bypass passage 18 is provided between the side wall 5 and the side wall 5. Opening 18 a of bypass passage 18 on connection pipe 15 side
Are located between the diaphragm 19 and the exhaust pipe 1. The enclosure 16 is provided with a gas inlet 17 for injecting air from the outside.

When external air is injected into the enclosure 16 from the gas inlet 17, the hydraulic exciter 20 in the enclosure 16 is cooled, and air is injected into the connection pipe 15 through the bypass passage 18. The gas is discharged into the exhaust pipe 1 through the vicinity of the vibration plate 19. That is, since the front and rear surfaces of the hydraulic speaker are cooled, the heat of the high-temperature gas in the exhaust pipe 1 is blocked by the air from the bypass passage 18 toward the hydraulic speaker, so that the heat of the high-temperature gas is It is protected from high temperatures without reaching the pressure speaker. At this time, the controller 7 detects the noise in the exhaust pipe 1 by the detection microphone 2 and sends a signal of a sound having a phase opposite to the obtained noise to the servo valve 22. Sound is generated. The controller 7 controls the volume and phase of the hydraulic speaker based on the signal obtained from the error microphone 4 so that the sound from the hydraulic speaker and the noise in the exhaust pipe 1 cancel each other out and are muted. .

Accordingly, an active silencer capable of silencing noise even when the exhaust gas flowing through the exhaust pipe is at a high temperature can be realized as described above.

[0043]

In summary, according to the present invention, the following excellent effects are exhibited.

Since the cooling means supplies the cooling gas to the front or the periphery of the muffling speaker, it is possible to realize an active silencer capable of muffling noise even when the temperature of the exhaust gas flowing through the exhaust pipe is high.

[Brief description of the drawings]

1 is a schematic <br/> schematic diagram of active noise cancellation device assumes the present invention.

FIG. 2 is a schematic view of another active silencer on which the present invention is based .

FIG. 3A is a schematic view of an embodiment of the active noise reduction device of the present invention, and FIG. 3B is an external view of a small hole in a circle C of FIG.

FIG. 4 is a schematic view of another embodiment of the present invention.

FIG. 5 is a schematic view of another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust pipe 3 Connecting pipe 5 Speaker for silencing 6 Enclosure 8 Cooling means (gas inlet)

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuaki Hayashi 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawa Shima-Harima Heavy Industries Co., Ltd. East 2 Technical Center (72) Inventor Takashi Kawai Toyosu 2-chome, Koto-ku, Tokyo 1-1 No. 1 Ishikawa-Shima-Harima Heavy Industries, Ltd., Tokyo No. 1 Factory (72) Inventor Tatsunori 2-1-1, Toyosu, Koto-ku, Tokyo Nishi 3-11-15 Toyosu, Koto-ku, Tokyo Ishikawa Shima-Harima Heavy Industries Co., Ltd. Inside the Toji Technical Center (72) Inventor Fumio Sato 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawa Shima-Harima Heavy Industries Co., Ltd. Inside the center (72) Inventor Kiichiro Kobe 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawa Shima-Harima Heavy Industries In the Toni Technical Center Co., Ltd. (72) Noriko Kano, 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawa Shimaharima Heavy Industries, Ltd. In the Toni Technical Center (72) Inventor, Yasuo Inoue 1 Hyakunincho, Shinjuku-ku, Tokyo No. 15-18, Ishikawashima Soundproofing Industrial Co., Ltd. (72) Inventor Takeshi Fuchiwaki 1-15-18 Hyakunincho, Shinjuku-ku, Tokyo Inside Ishikawashima Soundproofing Industrial Co., Ltd. (56) References JP-A-5-98927 ( JP, A) JP-A-50-62001 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 1/00 F01P 1/06 G10K 11/178

Claims (3)

(57) [Claims] 1. An active silencer in which an exhaust pipe through which a high-temperature exhaust gas flows is provided with a silencing speaker for generating a sound having a phase opposite to that of the noise in the exhaust pipe . Connect the connecting pipe and bend the connecting pipe
Are provided with a number of small holes, and a chamber is provided to cover the large number of small holes.
Only, the end of the connecting tube, the enclosure so as to cover the speaker digested sound is attached to mute the speaker provided, cooling means for supplying cooling gas to protect the mute speaker from a high temperature to the chamber An active silencer characterized by being provided. 2. An exhaust pipe through which high-temperature exhaust gas flows.
A muffling speaker that produces a sound in phase opposite to the noise in the exhaust pipe
In the active silencer provided with, the exhaust pipe side
Connect a connecting pipe to the wall, and attach a silencing spike to the end of the connecting pipe.
And cover the mute speaker.
An enclosure is provided, and the enclosure
Supply cooling gas to protect the speaker from high temperatures
Providing cooling means, the enclosure and the connection pipe;
Are connected by a bypass flow path, and the cooling gas is
Discharges from the outlet through the bypass passage to the connection pipe.
Active noise cancellation apparatus being characterized in that as that. 3. The sound-absorbing speaker according to claim 1 , wherein
And a hydraulic pressure driving the diaphragm
The active silencer according to claim 1, comprising a vibrator .