JPH0658125A - Active silencer - Google Patents

Abstract

PURPOSE:To support an oscillatory member and the like in its stable condition, in an active silencer provided with an acoustic wave output device having an annular oscillatory member arranged coaxially with an exhaust pipe. CONSTITUTION:An active silencer is provided with a first case 41 having a large diameter outer cylindrical part 41a and a small diameter inner cylindrical part 41b arranged coaxially inside of the outer cylindrical part 41a, and blocking a space between respective axial end parts of the inner cylindrical part 41b and the outer cylindrical part 41a, an acoustic wave output device 5 having an annular oscillatory member 51 arranged to be able to oscillate in axial direction between the inner cylindrical part 41b and the outer cylindrical part 41a of the first case 41, and supported on the first case 41, and a second case 42 which is brought in contact with the other axial end part of the outer cylindrical part 41a, and comparting a chamber opened in the acoustic wave output direction of the oscillatory member 51. The active silencer is supported in such a way that an exhaust pipe 3 is inserted in the inner cylindrical part 41b of the first case 41. Silencing is carried out in such a way that acoustic wave of antiphase is made to interface with exhaust noise by the acoustic wave output device 5.

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, an active silencer has been attracting attention, which outputs a sound wave that cancels the exhaust sound of an internal combustion engine to actively muffle the sound. For example, as described in Japanese Utility Model Laid-Open No. 63-118321, a speaker is provided in an exhaust pipe which is a noise outflow pipe with respect to an internal combustion engine which is a noise source, and the internal combustion engine is operated in response to a predetermined control signal from a control means. It is known that a noise is generated, that is, a compression and compression pressure wave, that is, a sound wave having a phase opposite to that of the exhaust sound is output from a speaker, and the sound is canceled by the canceling action of both sound waves. Further, Japanese Utility Model Laid-Open No. 4-15387 discloses an active cancel speaker in which a ring-shaped vibrating member is arranged between the outer circumference of the exhaust pipe and the inner circumference of the outer case.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the apparatus described in Japanese Patent Publication No. 87, the compression and compression pressure waves, that is, the sound waves, are uniformly output around the exhaust pipe by the diaphragm, and uniform characteristics are obtained on the outer circumference of the exhaust pipe, so that the silencing action is effectively performed. You can However, even in the device described in the publication, further improvement has been desired in terms of downsizing and weight reduction, ease of manufacturing and assembling, durability, and the like. In particular, the diaphragm support structure and the outer case support structure require consideration of durability.

In view of the above, the present invention provides an active silencer equipped with a sound wave output device having an annular vibrating member arranged coaxially with an exhaust pipe so that the vibrating member and the like can be supported in a stable state. To aim.

[0005]

In order to achieve the above object, the present invention provides an active muffler for suppressing noise by interfering sound waves of opposite phase with exhaust sound from an exhaust pipe of an internal combustion engine. A first case having an outer cylinder part having a diameter and an inner cylinder part having a small diameter arranged coaxially in the outer cylinder part, and closing one axial end portion of each of the inner cylinder part and the outer cylinder part. A sound wave output device having an annular vibrating member disposed axially between the inner cylinder portion and the outer cylinder portion of the first case so as to support the first case, A tubular second case that joins to the other axial end of the outer tubular portion and defines a chamber opening in the sound wave output direction of the vibrating member, and the inner tubular portion of the first case The exhaust pipe is inserted into and supported by.

In the active silencer, the outer tubular portion and the inner tubular portion are formed as separate bodies, and one axial end portion of each is joined by a wall portion to form the first case. It may be that.

[0007]

In the active silencer having the above structure, the housing is divided into the first case and the second case, and the exhaust pipe is inserted into and supported by the inner cylinder portion of the first case. Therefore, sufficient supporting strength can be obtained even after the second case is joined. 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 vibrating member of the sound wave output device vibrates in accordance with the level of the exhaust sound, and a sound wave having an opposite phase is output in the second case, which cancels out the exhaust sound. In this case, since the vibrating member is disposed so as to be axially vibrable between the inner tubular portion and the outer tubular portion, the vibrating member is fixed regardless of whether the sound wave output device is fixed to the inner tubular portion or the outer tubular portion. Vibrates in a stable state in the first case.

[0008]

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. An active silencer 4 is attached near the outlet 3a of the exhaust pipe 3. 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.

As shown in FIG. 1, the active silencer 4 has a first silencer.
The sound wave output device 5 is housed in a housing composed of a case 41 and a second case 42 of the first case 4
The sound wave output device 5 is supported by 1 to form a sound wave output unit. The first case 41 has a large-diameter outer cylinder portion 41a.
And a small-diameter inner cylinder portion 41b arranged coaxially with the outer cylinder portion 41a, and a wall portion 41c is provided between one of the axial end portions of both.
It has a closed shape. A flange portion 41d is formed on the other axial end portion of the outer tubular portion 41a.
In the present embodiment, these outer cylinder portion 41a, inner cylinder portion 41b,
The wall portion 41c and the flange portion 41d are integrally formed of the same metal material as the exhaust pipe 3, for example.

The sound wave output device 5 comprises a vibration plate 51 which is an annular vibration member, and a drive device 50 for driving the vibration plate 51. The drive device 50 is supported by the inner cylindrical portion 41b of the first case 41, and the vibration plate is formed. 51 is arranged so as to vibrate in the axial direction of the inner cylindrical portion 41b. Thus, the drive device 50 side of the sound wave output device 5 is surrounded by the first case 41 to form a so-called enclosure. Although the diaphragm 51 of this embodiment has an annular shape, it may have a conical shape having a hole at the center.

The driving device 50 is an electrodynamic device for converting an electric signal into mechanical vibration of the diaphragm 51, and a winding is wound around a bobbin 52 fixed to the central portion of the diaphragm 51 to form a movable coil 53. The movable coil 53 is arranged between the core 54 fitted into the inner cylindrical portion 41b of the first case 41 and the permanent magnet 55 joined to the core 54 and arranged outside with a predetermined gap. ing. Further, an elastic member 56 having a wavy cross section is joined to the outer peripheral surface of the bobbin 52 and the inner peripheral surface of the outer tubular portion 41a. When an AC voltage drive signal is supplied to the movable coil 53, the vibrating plate 51 vibrates and a compressional pressure wave, that is, a 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.

The second case 42 is a cylindrical body composed of a large diameter portion 42a, a small diameter portion 42b and an inclined portion 42c connecting these portions,
A flange portion 42d that abuts the flange portion 41d of the first case 41 is formed at the opening end of the large diameter portion 42a. The second case 42 is formed of, for example, a synthetic resin of a material different from that of the first case 41. As a result, the weight can be reduced, and various sizes and shapes can be set according to the type of vehicle to which it is applied. When the first case 41 is joined to the first case 41 with a bolt or the like, a so-called mixer (mixing portion) surrounding the outlet 3a of the exhaust pipe 3 is formed as shown in FIG.

As shown in FIG. 1, a residual sound detector 6 is provided on the small-diameter portion 42b of the second case 42, and the residual sound detector 6 exhausts the sound wave output from the sound wave output device 5. The residual sound of the interference effect on the sound is detected, and the 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 in the small diameter portion 42b is detected by the residual sound detector 6, and the adaptive controller 1
It is output to 0.

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 in response to the drive signal and vibrates in the axial direction of the exhaust pipe 3 at a predetermined frequency, and the exhaust gas in the second case 42 is exhausted. A sound wave having a phase opposite to that of the exhaust sound is output around the outlet 3a of the pipe 3 and interferes with the exhaust sound emitted from the exhaust pipe 3. That is, the exhaust sound is canceled within the opening cross section of the small diameter portion 42b of the housing 40 including the residual sound detector 6 by the interference action of the sound wave of the opposite phase to the exhaust sound. Therefore, an appropriate sound deadening region is formed in the opening cross-section portion of the small diameter portion 42b including the residual sound detector 6.

FIG. 3 shows another embodiment of the active silencer of the present invention. When the material of the first case 41 is different from that of the exhaust pipe 3, the first case 41 is attached to the bracket 43. It is to be joined to the exhaust pipe 3 via. That is, the bracket 43 is previously fixed to the exhaust pipe 3 by welding, for example, and the first case 41 is connected to the bracket 43 by the bolt and the nut 44, so that the assembly is easy.

FIG. 4 shows still another embodiment of the active silencer of the present invention, in which the inner cylinder portion 41b of the first case 41 is a separate member and is made of the same material as the first case 41. Although the tubular body 45 is joined to the wall portion 41c by welding, for example, the outer tubular portion 41a may be a separate member and joined to the wall portion 41c integrally formed with the inner tubular portion 41b in accordance with manufacturing requirements. May be Alternatively, in order to reduce heat transfer from the exhaust pipe 3 to the sound wave output device 5, the tubular body 45 may be formed of a heat insulating material.

[0019]

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 exhaust pipe is inserted into and supported by the inner cylinder of the first case, and the second case is joined to the outer cylinder of the first case. Therefore, sufficient supporting strength can be secured. Moreover, since the vibrating member is disposed so as to be axially vibrable between the inner tubular portion and the outer tubular portion, the vibrating member can vibrate in a stable state.

Further, since the first case and the second case are divided, they can be made of different materials. For example, the second case can be made of synthetic resin to reduce the weight. Furthermore, since the sound wave output unit can be configured by accommodating the sound wave output device in the first case, the assembly is easy, and the size of the sound wave output unit can be changed according to the type of vehicle to which the sound wave output unit is applied.
It is possible to join various second cases having different shapes.

In the above active silencer, if the outer cylinder part and the inner cylinder part of the first case are separately constructed, the first case of various modes can be manufactured in response to manufacturing requirements. Can be configured.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an active silencer of the present invention.

FIG. 2 is a configuration diagram showing an overall configuration of an embodiment of an active silencer 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.

[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 10 Adaptive controller 50 Drive device, 51 Vibration plate (vibration member)

Claims (2)

[Claims] 1. An active silencer for suppressing noise by interfering sound waves of opposite phase with exhaust sound from an exhaust pipe of an internal combustion engine, wherein a large diameter outer cylinder portion and a small diameter coaxially arranged inside the outer cylinder portion. A first case having an inner cylinder portion and closing one axial end portion of each of the inner cylinder portion and the outer cylinder portion, and the inner cylinder portion and the outer cylinder of the first case. A vibrating member that has an annular vibrating member that is axially oscillatably supported between the two parts, and that is joined to the other axial end of the outer tubular part and the sound wave output device that is supported by the first case. A cylindrical second case that defines a chamber that opens in the sound wave output direction, and the exhaust pipe is inserted into and supported by the inner cylindrical portion of the first case. Active silencer. 2. The outer cylinder part and the inner cylinder part are formed as separate bodies, and one axial end of each is joined by a wall part to form the first case. The active silencer according to claim 1, which is characterized in that.