JPH0658123A - Active silencer - Google Patents

Abstract

PURPOSE:To apply thermal insulation effectively to an exhaust pipe composition in a housing, in an active silencer provided with an acoustic wave output device and assigned carry out silencing by making acoustic wave having antiphase against exhaust noise from the exhaust pipe interfere with the exhaust noise. CONSTITUTION:An active silencer is provided in such constitution that an acoustic wave output device 5 is arranged in the vicinity of the outlet of the exhaust pipe 3 of an internal combustion engine, and also a housing 40 enclosing the outlet of the exhaust pipe 3 and at least the acoustic wave output side of the acoustic wave output device 5 is arranged, and acoustic wave of antiphase outputted from the acoustic output device 5 is made to interfere with the exhaust noise from the exhaust pipe 3 to carry out silencing. The end part of the exhaust pipe 3 positioned in the housing 40 is formed in a double pipe. The double pipe is formed in such constitution that one side of a clearance between pipe walls of the double pipe is communicated with the inside of the housing 40, and also the other side is communicated with the outside of the housing 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active silencer mounted on an internal combustion engine, and in particular, it is provided with a sound wave output device for outputting a sound wave having a phase opposite to the exhaust sound from an exhaust pipe, and the sound deadening is performed by the interference effect of the sound waves. The present invention relates to an active silencer for performing.

[0002]

2. Description of the Related Art Recently, attention has been paid to an active silencer that actively silences sound by interfering sound waves with the exhaust sound of an internal combustion engine. For example, Japanese Patent Publication No. 2-503219 discloses a configuration of an exhaust muffler device in an active sound reduction system. That is, the speaker is provided symmetrically with respect to the axis of the exhaust pipe, and the annular chamber surrounding the exhaust pipe is formed as an anti-noise chamber.

[0003]

9 and 10 show an example of a general arrangement of the speaker SP with respect to the exhaust pipe EX, as in the device described in the above publication. In FIG. 9, the housing H surrounds the outlet of the exhaust pipe EX.
1 is provided, and the speaker SP is arranged so as to output a sound wave in a direction orthogonal to the axis of the exhaust pipe EX. In the housing H1, an enclosure E1 is formed behind the speaker SP, and a mixer M1 including the front of the speaker SP and the outlet of the exhaust pipe EX is formed. Further, in FIG. 10, the speaker SP is arranged so as to output a sound wave in a direction parallel to the axis of the exhaust pipe EX. In the housing H2 provided in the exhaust pipe EX, an enclosure E2 is formed behind the speaker SP, and a mixer M2 including the front of the speaker SP and the outlet of the exhaust pipe EX is formed. The opening of the mixer M2 is slightly larger than the exhaust pipe EX, but the housing H2
The diameter is smaller than that of the main body portion, and the shape is a diaphragm shape from the main body portion to the opening portion, and a wall surface is provided upright in front of the speaker SP.

In these devices, the loudspeaker SP is heated when the temperature of the exhaust pipe becomes high due to the exhaust gas. Therefore, it is necessary to use a speaker having excellent heat resistance as this type of speaker. It becomes high. Particularly in the device shown in FIG. 10, the enclosure part E2 is also heated and the drive device part of the speaker Sp is also heated, so it is difficult to obtain the desired output performance.
Also, as for the microphone MC, since the housings H1 and H2 are heated by the heat radiation from the exhaust pipe, it is necessary to use a microphone having excellent heat resistance, resulting in a high cost.

Therefore, the present invention comprises a sound wave output device,
It is an object of the present invention to provide an active silencer that silences an exhaust sound from an exhaust pipe by interfering a sound wave having an opposite phase, so that the exhaust pipe located inside a housing can be effectively insulated.

[0006]

In order to achieve the above object, the present invention provides a sound wave output device in the vicinity of an outlet of an exhaust pipe of an internal combustion engine, and at the same time, at the outlet of the exhaust pipe and at least the sound wave output. In the active silencer, which is provided with a housing surrounding a sound wave output side of the device, and which cancels noise by interfering with an exhaust sound from the exhaust pipe, a sound wave of an opposite phase output from the sound wave output device. The end of the exhaust pipe located inside is a double pipe, and one side of the gap between the pipe walls of the double pipe communicates with the inside of the housing and the other side communicates with the outside of the housing. It was done.

In the active silencer, a residual sound detector is arranged at a predetermined position in the housing, which is substantially in the same direction as the outlet direction of the exhaust pipe and substantially in the same direction as the sound wave output direction of the sound wave output device. At the same time, it is preferable that the housing is formed in a shape in which the sound wave output from the sound wave output device is substantially directly transmitted to the residual sound detector except the exhaust pipe.

Further, in the active silencer, the housing surrounds the sound wave output device and forms an opening at a predetermined distance from the sound wave output device in the sound wave output direction, and in the vicinity of the opening. A residual sound detector is disposed in the exhaust pipe, and the exhaust pipe is arranged such that the outlet end of the exhaust pipe is located on the axis connecting the opening of the housing and the sound wave output device and opens toward the opening of the housing. It is preferable that the double-tube portion is bent and attached to the housing.

Further, in the active silencer, a pair of first gutter-shaped members having a substantially U-shaped cross section having flanges on both sides in the longitudinal direction are provided at the ends of the exhaust pipe. A pair of second gutter-shaped members having a substantially U-shaped cross-section, which are joined to each other so that the collars of the gutter-shaped members come into contact with each other, and have flanges on both sides in the longitudinal direction, are provided. It is advisable to form a double pipe by joining each of the collar portions so as to sandwich the respective collar portions of the pair of first gutter-shaped members.

[0010]

In the active silencer having the above structure, the exhaust pipe located in the housing is a double pipe, and the outside air is introduced into the gap between the pipe walls. Radiant heat from the exhaust pipe is blocked by the air layer. As a result, the temperature rise of the sound wave output device and the like is suppressed and the desired performance is maintained. Then, when the internal combustion engine is started and rotated, the explosion sound generated in response to the explosion in each cylinder is transmitted through the exhaust sound path including the exhaust pipe and is emitted as exhaust sound from the exhaust pipe. The sound wave output device operates according to the level of the exhaust sound, and the sound wave of the opposite phase is output in the housing, and the exhaust sound is canceled.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of an active silencer according to the present invention will be described below with reference to the drawings. 1 and 2 relate to an embodiment of the present invention. First, referring to FIG. 2 showing the overall configuration, an exhaust pipe 3 is connected to an exhaust manifold 2 of an internal combustion engine 1, and a catalytic converter 9 is interposed in the exhaust pipe 3. It is equipped. Therefore, the exhaust manifold 2, the catalytic converter 9, and the exhaust pipe 3 constitute an exhaust sound path for the internal combustion engine 1 which is an exhaust sound source. The exhaust pipe 3 is a double pipe in which an outer pipe 8 is provided at an end near the outlet 3a, and an active silencer 4 is attached to the double pipe portion. The active silencer 4 is provided with a sound wave output device 5 that outputs a sound wave, and a residual sound detector 6 that detects a residual sound near the outlet 3 a of the exhaust pipe 3. Further, a rotation signal detector 7 that outputs a signal synchronized with the rotation of the internal combustion engine 1 is provided, and is connected to the adaptive controller 10 together with the residual sound detector 6. This adaptive controller 10 has an adaptive digital filter and updates the coefficient of the transfer function of the adaptive digital filter by an adaptive algorithm according to the output signal of the residual sound detector 6 based on the output signal of the rotation signal detector 7 to obtain the residual sound. The sound wave output device 5 is driven and controlled so that the output signal of the detector 6 is minimized.

The active silencer 4 has a bottomed cylindrical housing 40 in which a sound wave output device 5 is housed, as shown in an enlarged view in FIG. 40 a is formed, and a mixer 40 b (mixing unit) is formed on the side of the sound wave output device 5 on which the diaphragm 51 is directed. The mixer 40b has an open end 40c.
The opening end 40c has an inner diameter slightly larger than the outer diameter of the outer tube 8, but is smaller than the outer diameter of the enclosure 40a portion, and has a narrowed shape. The enclosure 40a portion and the mixer 40b portion may be formed of different materials and the two portions may be joined together.

The sound wave output device 5 of this embodiment is a cone speaker type, and comprises a diaphragm 51 and a driving device 50 for driving the diaphragm 51. The driving device 50 is supported by the housing 40, and the diaphragm 51 is in the axial direction. It is arranged so as to vibrate and output a sound wave in the mixer 40b. The driving device 50 is an electrodynamic device that converts an electric signal into mechanical vibration of the diaphragm 51. When the driving signal of the AC voltage is supplied to the movable coil (not shown), the diaphragm 51 vibrates and the coarse and fine components are generated. A pressure wave or sound wave is output. The drive device 50 is not limited to the above, but a coil is wound around a core connected to a permanent magnet, and a drive signal is supplied to this coil to generate a vibration plate 51.
It is also possible to configure an electromagnetic type device that vibrates. Besides this, electrostatic type used in the field of speakers,
Various configurations such as electrostrictive type and magnetostrictive type can be adopted,
Further, the diaphragm 51 may be hydraulically driven to ensure high output.

An exhaust pipe 3 is attached to the housing 40 so as to penetrate through a wall 40d on the opposite side of the opening end 40c and parallel to the direction of the diaphragm 51, and an outlet 3a is opened in the mixer 40b. Exhaust pipe 3 located in housing 40
As shown in FIG. 1, the end of the double-tube structure has a double tube structure. That is, the outer pipe 8 is provided at the end of the exhaust pipe 3 near the outlet 3a so that a predetermined gap is formed over the entire circumference thereof. One side of the gap between the exhaust pipe 3 and the wall of the outer pipe 8 (the end 8a side of the outer pipe 8) is the housing 40.
The other side (the end 8b side of the outer pipe 8) communicates with the outside of the housing 40. The end portion 8b on the front side (internal combustion engine 1 side) of the outer pipe 8 of the present embodiment has a housing 40
It is expanded radially outside.

Further, a residual sound detector 6 is provided at the opening end 40c of the housing 40, and the residual sound detector 6 produces a residual sound which is an interference effect of the output sound wave of the sound wave output device 5 on the exhaust sound. It is detected and a signal corresponding to this is output. Note that the residual sound detector 6 may take any form, such as a microphone and a pressure sensor, as long as it is a means for converting a pressure signal into an electric signal.

Next, the operation of the active silencer of this embodiment will be described. When the internal combustion engine 1 is started and rotated, the explosion sound generated in response to the explosion in each cylinder is transmitted through the exhaust sound path of the exhaust manifold 2, the catalytic converter 9 and the exhaust pipe 3 to form exhaust sound. Then, a rotation signal synchronized with the rotation of the internal combustion engine 1 is output to the adaptive controller 10. Further, the residual sound at the opening end portion 40 c is detected by the residual sound detector 6 and output to the adaptive controller 10.

In the adaptive controller 10, the transfer function of the adaptive digital filter is identified as the transfer function of the exhaust sound path by an adaptive algorithm corresponding to the output signal of the residual sound detector 6 based on the output signal of the rotation signal detector 7. That is, the coefficient is updated so that the output signal of the residual sound detector 6 is minimized, and the drive signal is output to the sound wave output device 5 accordingly. When a drive signal is input to the drive device 50 of the sound wave output device 5, the diaphragm 51 is driven accordingly and vibrates at a predetermined frequency.
A sound wave having a phase opposite to that of the exhaust sound is output in b and interferes with the exhaust sound emitted from the outlet 3a of the exhaust pipe 3. That is, due to the interference action of the sound waves of opposite phase to the exhaust sound
The exhaust noise is canceled within the opening cross section of the opening end portion 40c of the housing 4 including the residual sound detector 6. Therefore, an appropriate sound deadening region is formed in the opening cross section of the opening end 40c including the residual sound detector 6.

In connection with the above operation, the housing 40 is provided by the exhaust gas flow discharged from the outlet 3a of the exhaust pipe 3 at a high speed.
The air inside is dragged, and as a result, outside air at room temperature is introduced into the housing 40 through the gap between the exhaust pipe 3 and the wall of the outer pipe 8. Since a new air layer of fresh air is constantly formed in the gap between the exhaust pipe 3 and the outer pipe 8, the radiant heat from the exhaust pipe 3 is blocked by this air layer, and the temperature in the enclosure 40a of the housing 40 and the mixer 40b is reduced. The rise is suppressed. As a result, a good operating state of the sound wave output device 5 is maintained and durability is improved. Further, since an air layer at room temperature is formed around the exhaust gas ejected from the outlet 3a of the exhaust pipe 3, diffusion of heat of the exhaust gas is suppressed and heating of the residual sound detector 6 is prevented. The exhaust gas is prevented from flowing into the housing 40. Furthermore, when the vehicle is traveling, the traveling wind flows into the gap between the exhaust pipe 3 and the outer pipe 8 and the amount of air passing therethrough increases, so that the heat insulating effect is further enhanced. Moreover, in this embodiment, since the front end 8b of the outer tube 8 is expanded and formed in a tapered shape, the inflow of traveling wind is promoted.

FIG. 3 shows another embodiment of the active silencer of the present invention. The sound wave output device 5 of the embodiment of FIG. 1 is arranged so as to output sound waves in parallel with the axis of the exhaust pipe 3. On the other hand, in the present embodiment, the sound wave output device 5 is arranged so as to output a sound wave in the direction perpendicular to the axis of the exhaust pipe 3. The shapes of the housing 41, the enclosure 41a, and the mixer 41b of this embodiment are different from those of the embodiment of FIG. 1, but the rest of the configuration is the same as that of the embodiment of FIG. Is attached and the description is omitted. Thus, also in this embodiment, the temperature rise in the mixer 41b of the housing 41 can be suppressed by the air layer between the exhaust pipe 3 and the outer pipe 8.

FIG. 4 shows still another embodiment of the active silencer of the present invention. The enclosure 42a and the mixer 42b of the housing 42 in this embodiment are a diaphragm 51.
The opening end having an axis (indicated by the alternate long and short dash line B) that is substantially in the same direction as the orientation of the diaphragm 51 on the side where It communicates with the atmosphere via 42c. In addition, the housing 42
The exhaust pipe 3 and the outer pipe 8 are attached through the side wall 42d of the housing 42 from the same direction as the axis C of the opening end 42c of the housing, that is, the direction forming a predetermined angle with respect to the direction of the diaphragm 51, and the outlet 3a. Has an opening in the mixer 42b. Therefore, as in the above-described embodiment, the radiant heat from the exhaust pipe 3 is blocked by the air layer between the exhaust pipe 3 and the wall of the outer pipe 8,
The temperature rise in the mixer 42b is suppressed. Then, the residual sound detector 6 is attached to the opening end portion 42c so as to be positioned substantially in the same direction as the directing direction of the diaphragm 51, that is, in the output direction of the sound wave, and in the substantially same direction as the outlet direction of the exhaust pipe 3. ing.

By the way, the adaptive controller 10
Is an input signal of the output signal of the rotation signal detector 7 and a detection signal of the residual sound detector 6, that is, an error signal, and remains in a muffling area (installation position of the residual sound detector 6) in which the output sound wave and the exhaust sound are canceled. The sound wave output device 5 outputs sound waves having opposite phases so that the sound becomes minimum.
However, the signal output from the adaptive controller 10 at that time is affected by acoustic transmission from the sound wave output device 5 to the sound deadening region, unlike the signal representing the output sound wave that actually reaches the sound deadening region. Therefore, the adaptive controller 10 needs to correct the acoustic transfer characteristics from the sound wave output device 5 to the sound deadening region.

There are two methods for this correction. One is a method using a constant value as a correction value on the assumption that the transfer characteristic from the sound wave output device 5 to the residual sound detector 6 is constant. The other one is a method in which the correction value itself is sequentially identified and updated while performing active cancellation. The latter correction method requires a system for measuring the transfer characteristics from the sound wave output device 5 to the residual sound detector 6, and also increases the amount of calculation, which causes a change in a wide frequency band such as vehicle exhaust noise. If the target is a loud sound,
High-speed calculation is required for the noise reduction, and the cost becomes very expensive. Therefore, it is realistic to use the former correction method.

However, since the former correction method is premised on the condition that "the transfer characteristic from the sound wave output device 5 to the residual sound detector 6 is always constant", the frequency range is wide and the change is drastic, and the environment is large. It is not easy to apply it to exhaust noise that has a sharp temperature change. According to the present embodiment, as described above, the output sound wave of the sound wave output device 5 is substantially directly transmitted to the residual sound detector 6 which is substantially in the same direction as the output direction, and the residual sound detector 6 is Since the exhaust pipe 3 is located substantially in the same direction as the outlet 3a direction, it is possible to stabilize the acoustic transfer characteristic from the sound wave output device 5 to the residual sound detector 6, and the output fluctuation is small in a wide frequency band and high. It is possible to maintain the characteristics and obtain the characteristics in which the phases are uniform. Therefore,
The sound deadening performance can be further improved as compared with the above two embodiments.

FIG. 5 shows another embodiment of the present invention.
From the front of the housing 43 (internal combustion engine 1 side), the exhaust pipe 3
And the outer tube 8 is mounted through the wall 43d of the housing 43 and the outlet 3a is open in the mixer 43b.
It opens in the e direction. At this time, the outlet end 3 of the exhaust pipe 3
The exhaust pipe 3 and the outer pipe 8 are arranged so that b is located on the axis connecting the opening 43e of the housing 43 and the sound wave output device 5.
However, as shown in FIG. 5, it is bent and formed in a substantially crank shape while maintaining the gap between the pipe walls. Further, the housing 43
A residual sound detector 6 is provided in the vicinity of the opening 43e of the diaphragm 51 substantially in the directivity direction of the diaphragm 51.
At, the residual sound of the interference effect with the exhaust sound due to the output sound wave of the sound wave output device 5 is detected, and the signal corresponding to this is output.

According to this embodiment, the air space between the exhaust pipe 3 and the outer pipe 8 allows the enclosure 4 of the housing 43 to be enclosed.
It is possible to suppress the temperature rise in 3a and the mixer 43b. Further, the output sound wave of the sound wave output device 5 is substantially directly transmitted to the residual sound detector 6 located substantially in the same direction as the output direction thereof, and is coaxial with the exhaust sound emitted from the outlet 3a of the exhaust pipe 3. Therefore, as in the embodiment of FIG. 4, it is possible to stabilize the acoustic transfer characteristics from the sound wave output device 5 to the residual sound detector 6, and maintain high characteristics with a small output fluctuation in a wide frequency band and maintain the phase. Uniform characteristics can be obtained.

FIG. 6 shows another embodiment of the active silencer of the present invention. In the embodiment of FIG. 5, the exhaust pipe 3 and the outer pipe 8 penetrate the front wall portion 43d of the housing 43. On the other hand, in the present embodiment, it is attached by penetrating the side wall 44f of the housing 44 of the bottomed cylindrical body which is symmetrical in the axial direction. An enclosure 44a is formed on the drive device 50 side of the sound wave output device 5, and a mixer 44b is formed in the directivity direction of the diaphragm 51. The opening 44e is coaxial with the mixer 44b, but is formed with a small diameter to form a diaphragm opening. The residual sound detector 6 is provided in the vicinity of the opening 44e, and therefore is located in the directional direction of the diaphragm 51. On the other hand, the exhaust pipe 3 is bent in a substantially crank shape, and the side wall 44f is obliquely formed with respect to the housing 44.
Of the residual sound detector 6 and the opening 44.
It is attached so as to be located on the axis connecting with e.

Thus, in this embodiment, the opening 44
Although the arrangement relationship of e, the exhaust pipe 3 and the outer pipe 8, the sound wave output device 5, and the residual sound detector 6 is the same as that of the embodiment of FIG.
The housing 44 can be made small. Also,
Since the exhaust pipe 3 does not penetrate the enclosure 44a and can be installed separately from the sound wave output device 5, the thermal influence of the exhaust pipe 3 on these can be reduced. Moreover, since the housing 44 is symmetrical in the axial direction, strength is obtained and the sound wave output state is uniform.

The double pipe structure of the end portion of the exhaust pipe 3 and the outer pipe 8 used in the above embodiment is press-fitted between them through a spacer or the like, or on the outer surface of the end portion of the exhaust pipe 3. It can be formed by fixing the support member by welding or the like and press-fitting the outer pipe 8. However, when the gap between the exhaust pipe 3 and the outer pipe 8 is narrow, welding is difficult, and when the thermal expansion amounts of the two are different, fixing by press fitting becomes uncertain. Furthermore, as shown in FIG. 8, when it is necessary to bend and form the double pipe portion of the exhaust pipe 3 and the outer pipe 8,
It is difficult to form the double pipe part.

7 and 8 show a part of the exhaust pipe of the double pipe structure used in the above-mentioned embodiment, and the outer pipe 8 is joined to the end portion of the exhaust pipe 3. In FIG.
The exhaust pipe 3 and the outer pipe 8 are divided into two by an axial surface. That is, the exhaust pipe 3 is formed by joining the gutter-shaped first member 31 and second member 32 having a substantially U-shaped cross-section in which the flange portions 31a and 31b and the flange portions 32a and 32b are formed on both sides in the longitudinal direction. It is formed in a cylinder. Similarly, the outer tube 8
Also, a gutter-shaped first member 81 and a second member 82 each having a substantially U-shaped cross section, in which the brim portions 81a and 81b and the brim portions 82a and 82b are formed on both sides in the longitudinal direction of each, are joined to form a tubular body. It These first member 31, second member 32, first member 8
Each of the first and second members 82 is formed by pressing a metal plate, and these are joined as shown in FIG. 7, and the collar portions 31a, 32a, 81a, 81a are fixed by welding or the like, and the collar portion is 31b, 32b, 81b and 81b are fixed.

Thus, the gap between the pipe walls of the exhaust pipe 3 and the outer pipe 8 depends on the difference between the outer diameter of the exhaust pipe 3 and the inner diameter of the outer pipe 8, and the width of the flange portions 31a, 32a, 31b, 32b. Are set in advance, and these outer ends and the flange portions 81a, 82a, 8 of the outer tube 8 are set.
The desired gap size can be set by matching the outer ends of the 1b and 82b. Thus, the exhaust pipe having the double pipe structure can be manufactured by a simple method with a small number of parts. Similarly, an exhaust pipe having a bent double pipe structure as shown in FIG. 8 can be easily manufactured.

[0031]

Since the present invention is configured as described above, it has the following effects. That is, in the active silencer of the present invention, the end portion of the exhaust pipe located inside the housing is a double pipe, and the outside air is introduced into the gap between the pipe walls. Since the radiant heat from the exhaust pipe is cut off, the thermal influence on the sound wave output device and the like can be reduced.

Further, in the active silencer according to the second and third aspects, the output sound wave having a proper opposite phase interferes with the exhaust sound, and the output sound wave is transmitted at a low rate as a reflected sound. The short path makes it less susceptible to temperature. Thus, the acoustic transfer characteristics between the sound wave output device and the residual sound detector are stable, and good silencing performance can be secured.

Further, in the active silencer according to the fourth aspect, since the exhaust pipe having the double pipe portion which can be easily manufactured can be constituted, it can be manufactured inexpensively and appropriately.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of an embodiment of an active silencer of the present invention.

FIG. 2 is an enlarged sectional view of an active silencer according to an embodiment of the present invention.

FIG. 3 is a sectional view of another embodiment of the active silencer of the present invention.

FIG. 4 is a sectional view of still another embodiment of the active silencer of the present invention.

FIG. 5 is a cross-sectional view of another embodiment of the active silencer of the present invention.

FIG. 6 is a sectional view of still another embodiment of the active silencer of the present invention.

FIG. 7 is a perspective view showing a double pipe structure of an exhaust pipe provided for the active silencer of the present invention.

FIG. 8 is a perspective view showing a double pipe structure of a bent exhaust pipe used for the active silencer of the present invention.

FIG. 9 is a cross-sectional view showing an example of a general arrangement of speakers with respect to an exhaust pipe and an example of a housing shape.

FIG. 10 is a cross-sectional view showing another general arrangement example of the speakers with respect to the exhaust pipe and another housing shape example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust manifold 3 Exhaust pipe 4 Active silencer 5 Sound wave output device 6 Residual sound detector 7 Rotation signal detector 8 Outer pipe 10 Adaptive controller 40 Housing 50 Drive device

Claims (4)

[Claims] 1. A sound wave output device is disposed near an outlet of an exhaust pipe of an internal combustion engine, and a housing surrounding the outlet of the exhaust pipe and at least a sound wave output side of the sound wave output device is disposed, the exhaust gas. With respect to the exhaust sound from the pipe, in the active silencer for silencing by interfering the sound waves of the opposite phase output from the sound wave output device, the end portion of the exhaust pipe located in the housing is a double pipe, An active silencer, characterized in that one side of a gap between the pipe walls of the double pipe communicates with the inside of the housing and the other side communicates with the outside of the housing. 2. A residual sound detector is disposed at a predetermined position of the housing that is substantially in the same direction as the outlet direction of the exhaust pipe and substantially in the same direction as the sound wave output direction of the sound wave output device. 2. The active silencer according to claim 1, wherein the housing is formed in a shape in which an output sound wave of the sound wave output device is directly transmitted to the residual sound detector except the exhaust pipe. 3. The housing surrounds the sound wave output device and forms an opening at a predetermined distance from the sound wave output device in the sound wave output direction, and a residual sound detector is arranged in the vicinity of the opening. And bend the double pipe portion of the exhaust pipe so that the outlet end of the exhaust pipe is located on the axis connecting the opening of the housing and the sound wave output device and opens toward the opening of the housing. The active silencer according to claim 1, which is formed and attached to the housing. 4. The end portion of the exhaust pipe is provided with a pair of first gutter-shaped members having substantially U-shaped cross-sections having brims on both sides in the longitudinal direction, and each of the pair of first gutter-shaped members has a collar. The parts are joined so that they come into contact with each other, and substantially U having flange parts on both sides in the longitudinal direction.
A pair of second gutter-shaped members having a V-shaped cross-section, wherein the brim portions of the pair of second gutter-shaped members are respectively joined so as to hold each of the brim portions of the pair of first gutter-shaped members; The active silencer according to claim 1, which is a heavy pipe.