JPH06249387A - Muffler - Google Patents

Abstract

PURPOSE:To perform reliable muffling even when a noise frequency of exhaust gas passing through an exhaust gas pipe is changed, to reduce size, and to reduce an occupying area. CONSTITUTION:A muffler is formed such that a branch pipe 3 is disposed along an exhaust gas pipe 1 and the two ends of the branch pipe 3 are communicated to the exhaust gas pipe 1 and noise of exhaust gas passing through the exhaust gas pipe 1 is offset with noise of exhaust gas flowing in the branch pipe 3. In the muffler, a resonance plate 4 is exchangeably disposed in the branch pipe 3 along the traverse direction of the branch pipe 3. A resonance plate moving device 5 to move the resonance plate 4 along the longitudinal direction of the branch pipe 3 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for reducing noise in exhaust gas discharged from a refuse incinerator, a gas turbine, an engine and the like.

[0002]

2. Description of the Related Art Conventionally, there is a muffler of this type shown in FIG. This is a system in which a branch pipe 2 is disposed along an exhaust pipe 1 of a refuse incinerator or the like, and both ends of the branch pipe 2 are communicated with the exhaust pipe 1, and the exhaust gas passing through the exhaust pipe 1 is exhausted. After a part of it has branched and passed through the branch pipe 2,
It joins the exhaust gas of the exhaust pipe 1 again.

According to the above structure, the discharge speed of the exhaust gas passing through the branch pipe 2 is delayed by the length of the branch pipe 2 being longer than the discharge speed of the exhaust gas passing through the exhaust pipe 1. The noise frequency of the exhaust passing through the exhaust pipe 1,
180 ° phase of noise frequency of exhaust gas passing through the branch pipe 2
The phases are shifted so that the exhaust gas passing through the exhaust pipe 1 and the exhaust gas passing through the branch pipe 2 interfere with each other, and the noises of the two exhaust gases are canceled each other.

[0004]

SUMMARY OF THE INVENTION In the above conventional configuration,
Since the length of the branch pipe 2 is constant and the phase shift of the noise frequency of the exhaust gas passing through the branch pipe 2 is determined by the length of the branch pipe 2, the noise frequency of the exhaust gas passing through the exhaust pipe 1 changes. If you can not mute effectively.

Further, since the noise intensity of the exhaust gas passing through the branch pipe 2 is determined by the cross-sectional area of the branch pipe 2, in order to effectively muffle the noise, the noise of the exhaust pipe 1 has the same diameter as that of the exhaust pipe 1. It is necessary to use the branch pipe 2, which increases the size of the device,
The occupied area becomes large.

In view of the above-mentioned conventional problems, the present invention is capable of reliably muffling noise even when the noise frequency of the exhaust gas passing through the exhaust pipe changes, is compact, and occupies a small area. Is intended to provide.

[0007]

In order to achieve the above object, the present invention provides a branch pipe arranged along an exhaust pipe, and both ends of the branch pipe are communicated with the exhaust pipe. In a muffler for canceling noise of exhaust gas passing through the branch pipe by noise of exhaust gas flowing into the branch pipe, a resonance plate is replaceably arranged in the branch pipe along a transverse direction of the branch pipe. A resonance plate moving device for moving the plate along the longitudinal direction of the branch pipe is provided.

[0008]

In the above structure, first, the resonance plate having the natural frequency matching the noise frequency of the exhaust gas passing through the exhaust pipe is attached to the branch pipe. As a result, a part of the exhaust gas passing through the exhaust pipe 1 flows into the branch pipe to cause the resonance plate to resonate, and a sound wave having the same frequency as the noise frequency of the exhaust gas passing through the exhaust pipe is emitted from the resonance plate.

Next, the resonance plate moving device appropriately moves the resonance plate to shift the frequency phase of the sound wave emitted from the resonance plate by 180 ° with respect to the noise frequency of the exhaust gas passing through the exhaust pipe. Set to the opposite phase. Thereby, the noise of the exhaust gas passing through the exhaust pipe 1 can be effectively canceled by the sound wave emitted from the resonance plate.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a silencer according to an embodiment of the present invention, in which a branch pipe 3 is provided along an exhaust pipe 1 of a refuse incinerator and the like, and inside the branch pipe 3. A resonance plate 4 attached to the central portion and a resonance plate moving device 5 for moving the resonance plate 4 are provided.

The branch pipe 3 has an upstream end pipe 3a and a downstream end pipe 3b integrally provided on the exhaust pipe 1, and the end pipes 3a and 3b.
a. Bellows-shaped telescopic tubes 3c, 3 respectively connected to 3b
and a part of the exhaust gas passing through the exhaust pipe 1 is branched and flows into the branch pipe 3.

The resonance plate 4 is made of a material having excellent resonance and anticorrosion property, for example, a stainless plate.
, A plurality of types having different natural frequencies are prepared in advance, and the resonance plate 4 having a natural frequency matching the noise frequency of the exhaust gas passing through the exhaust pipe 1 is the expansion pipes 3c, 3
is inserted through d between the ring-shaped elastic spacers 6 and 6,
The branch pipe 3 is formed by integrally connecting the ends of the two expansion pipes 3c and 3d with each other by a connecting tool 7 such as a bolt and a nut.
Mounted on.

In the above structure, part of the exhaust gas passing through the exhaust pipe 1 flows into the branch pipe 3 to cause the resonance plate 4 to resonate, and has the same noise frequency as the exhaust gas passing through the exhaust pipe 1 from the resonance plate 4. Sound waves of frequency are emitted.

Further, since the resonance plate 4 resonates, the noise caused by the sound waves emitted from the resonance plate 4 is magnified more than the noise flowing into the branch pipe 3. It is not necessary to enlarge the noise by enlarging the cross-sectional area, the device can be downsized, and the occupied area can be reduced.

The resonance plate moving device 5 includes one expansion tube 3
A nut 8 connected to d, a screw rod 9 that is screwed into the nut 8, and a drive device that moves the resonance plate 4 along the longitudinal direction of the branch pipe 3 by rotating the screw rod 9 in the forward and reverse directions. 1
0, and the drive unit 1 based on the detection signal from the residual noise sensor 11 provided on the downstream side of the branch pipe 3 in the exhaust pipe 1.
And a muffling control device 12 for controlling 0.

In the above structure, the muffler control device 12 controls the driving machine 10 to move the resonance plate 4 appropriately, and when the residual noise detected by the residual noise sensor 11 becomes minimum, the resonance plate 4 moves. To stop. As a result, the phase of the frequency of the sound wave emitted from the resonance plate is opposite to that of the noise frequency of the exhaust gas passing through the exhaust pipe by 180 °, and the noise of the exhaust gas passing through the exhaust pipe 1 is emitted from the resonance plate. Can be effectively canceled by the sound waves.

Explaining how to muffle the sound, first, the exhaust pipe 1
A resonance plate 4 having a natural frequency matching the noise frequency of the exhaust gas passing through is attached to the branch pipe 3. As a result, a part of the exhaust gas passing through the exhaust pipe 1 flows into the branch pipe 3 to cause the resonance plate 4 to resonate, and a sound wave having the same frequency as the noise frequency of the exhaust gas passing through the exhaust pipe 1 is generated from the resonance plate 4. Is fired.

Next, the resonance plate moving device 5 appropriately moves the resonance plate 4 so that the frequency phase of the sound wave emitted from the resonance plate 4 is relative to the noise frequency of the exhaust gas passing through the exhaust pipe 1. The opposite phase is offset by 180 °. Thereby, the noise of the exhaust gas passing through the exhaust pipe 1 can be effectively canceled by the sound wave emitted from the resonance plate 4.

[0019]

According to the present invention, even when the noise frequency of the exhaust gas passing through the exhaust pipe changes, a resonance plate having a natural frequency matching the change is attached to the branch pipe, and the resonance plate is appropriately used. By moving it, a sound wave having a phase opposite to that of the noise can be emitted from the resonance plate, and the noise can be effectively canceled.

In addition, since the above-mentioned resonance plate resonates,
Since the noise caused by the sound waves emitted from the resonance plate is magnified more than the noise flowing into the branch pipe, it is not necessary to increase the cross-sectional area of the branch pipe to increase the noise as in the conventional case, and the device can be downsized. Therefore, the occupied area can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a silencer according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a conventional example.

[Explanation of symbols]

 1 Exhaust pipe 3 Branch pipe 4 Resonance plate 5 Resonance plate moving device

Claims (1)

[Claims] 1. A branch pipe is arranged along an exhaust pipe, both ends of the branch pipe are communicated with the exhaust pipe, and noise of exhaust gas passing through the exhaust pipe flows into the branch pipe. In the muffling device that cancels with, a resonance plate is replaceably arranged in the branch pipe along the transverse direction of the branch pipe, and the resonance plate moves to move the resonance plate along the longitudinal direction of the branch pipe. A silencer, which is provided with a device.