JPH0658130A - Active silencer - Google Patents

Abstract

PURPOSE:To prevent mixing of wave generated on a side opposite to the acoustic wave output side of an oscillatory member so as to carry out silencing property, 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 an acoustic wave output device 5 having an annular oscillatory member (oscillatory plate 51) arranged around an exhaust pipe 3 and being supported to be able to oscillate in axial direction of the exhaust pipe 3, and a housing 40 for enclosing at least the acoustic wave output device 5 and being supported on the exhaust pipe 3. Blocking members (bellows 43, 45) are arranged to close a clearance formed on at least one side of the inner and outer circumferential sides of the oscillatory member (oscillatory plate 51). Silencing is carried out in such a way that acoustic wave of antiphase is made to interfere 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 cancellation 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, in the device described in the publication, when a gap is formed between the outer case and the diaphragm or between the diaphragm and the exhaust pipe, the sound wave output side of the diaphragm (exhaust gas is exhausted through this gap). The sound wave generated on the opposite side to the exit side of the pipe) goes around to the sound wave output side. Since the sound wave generated on the opposite side has a phase opposite to that of the sound wave output from the sound wave output side, if mixed with the output sound wave that should interfere with the exhaust sound, it becomes difficult to perform accurate silencing.

Therefore, the present invention relates to an active silencer equipped with a sound wave output device having an annular vibrating member arranged coaxially with an exhaust pipe. The purpose is to prevent mixing and to perform an appropriate silencing effect.

[0005]

In order to achieve the above object, the present invention provides an active silencer for silencing sound by interfering sound waves of opposite phase with exhaust sound from an exhaust pipe of an internal combustion engine. A sound wave output device having an annular vibrating member disposed around the exhaust pipe and oscillatingly supported in the axial direction of the exhaust pipe; and a housing surrounding at least the sound wave output device and supporting the exhaust pipe, A closing member for closing a gap formed on at least one of the inner and outer peripheral sides of the vibrating member is provided.

In the active silencer, it is preferable that the closing member is formed of an annular bellows that is joined to either one of the housing and the exhaust pipe and is joined to the vibrating member.

Further, in the active silencer, the closing member may be formed of a cylindrical spacer interposed between any one of the housing and the exhaust pipe and the vibrating member.

[0008]

In the active silencer having the above structure, 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. Sound is emitted from the exhaust pipe. The vibrating member of the sound wave output device vibrates according to the level of the exhaust sound, and a sound wave having an opposite phase to the exhaust sound is output into the housing,
This is offset by the exhaust sound. In this case, since the gap formed on at least one side of the inner peripheral side and the outer peripheral side of the vibrating member is closed by the closing member, the sound wave generated on the opposite side of the vibrating member with respect to the output sound wave of the vibrating member. Does not mix with the output sound wave through the above-mentioned gap, so that the desired output sound wave can be interfered with the exhaust sound.

[0009]

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 is provided with a sound wave output device 5 supported by the exhaust pipe 3 and a housing 40. The housing 40 includes a large diameter portion 40a, a small diameter portion 40b, an inclined portion 40c therebetween, and a large diameter portion 4
The sound wave output device 5 is housed in the large-diameter portion 40a, which is a tubular body that is configured by a wall portion 40d that closes the exhaust pipe 3 and that is fixed to the exhaust pipe 3.

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 exhaust pipe 3, and the vibration plate 51 is the shaft of the exhaust pipe 3. It is arranged so that it can vibrate in the direction. The drive device 50 side of the sound wave output device 5 is surrounded by the large-diameter portion 40a of the housing 40 to form a so-called enclosure. Although the diaphragm 51 of this embodiment has an annular shape,
The shape may be a cone having a hole at the center.

As shown in FIG. 1, the exhaust pipe 3 and the housing 40 are provided on the inner peripheral side and the outer peripheral side of the diaphragm 51 of this embodiment, respectively.
Although a gap is formed between them, bellows 43 and 45 are arranged so as to close these gaps.
These bellows 43 and 45 are annular members formed of a flexible elastic material, and separate the spaces on both sides of the diaphragm 51 without disturbing the vibration action of the diaphragm 51.

The drive device 50 is an electrodynamic type device that converts 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 so that a movable coil 53 is formed. The movable coil 53 is arranged between the core 54 fitted to the exhaust pipe 3 and the permanent magnet 55 which is joined to the core 54 and is arranged outside with a predetermined gap.
Further, an elastic member 56 having a corrugated cross section is joined to the outer peripheral surface of the bobbin 52 and the inner peripheral surface of the large diameter portion 40a. 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.

Further, a residual sound detector 6 is provided on the small-diameter portion 40b of the housing 40, and the residual sound detector 6 produces a residual sound due to an interference effect on the exhaust sound by the output sound wave of the sound wave output device 5. It is detected and a signal corresponding to this is output. If the residual sound detector 6 is a means for converting a pressure signal into an electric signal, such as a microphone and a pressure sensor,
Any form may be used.

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 40b 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, so that the exhaust pipe 3 in the housing 40 is driven. A sound wave having a phase opposite to the exhaust sound is output around the outlet 3a and interferes with the exhaust sound emitted from the exhaust pipe 3. That is, the exhaust sound is canceled in the opening cross section of the small diameter portion 40b 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 of the small diameter portion 40b including the residual sound detector 6.

In this case, since the gaps on the inner peripheral side and the outer peripheral side of the vibration plate 51 are closed by the bellows 43 and 45, respectively, on the sound wave output side of the vibration plate 51 (the outlet 3a side of the exhaust pipe 3). On the other hand, the sound wave generated on the opposite side (drive device 50 side) does not wrap around to the sound wave output side. Therefore, the interference effect of the desired output sound wave from the diaphragm 51 against the exhaust sound is secured.

FIG. 3 shows another embodiment of the active silencer of the present invention, in which the gap between the inner peripheral side of the vibration plate 51 and the outer peripheral surface of the exhaust pipe 3 is minimized, and the outer periphery of the vibration plate 51 is reduced. The bellows 45 is provided only on the side. As a result, the vibration plate 51 can be provided by providing only one bellows 45.
It is possible to substantially prevent mixing of the sound wave from the side opposite to the sound wave output side with respect to the output sound wave.

FIG. 4 shows still another embodiment of the active silencer of the present invention, in which a cylindrical spacer 44 around the exhaust pipe 3 is provided.
And the inner peripheral side of the diaphragm 51 is slidably arranged with respect to the spacer 44. As a result, it is possible to substantially prevent the mixing of sound waves from the side opposite to the sound wave output side as in the embodiment of FIG. 3, and the supporting state of the diaphragm 51 is improved, so that stable vibration action can be secured. it can. An annular spacer (not shown) may be provided on the inner peripheral side of the vibration plate 51 so as to be slidable with respect to the outer peripheral surface of the exhaust pipe 3. Alternatively, the bellows 43 may be provided only on the inner peripheral side of the diaphragm 51 as shown in FIG. 1, and the outer peripheral side may be configured similarly to the inner peripheral side of the diaphragm 51 shown in FIG. 3 or 4.

FIG. 5 shows another embodiment of the active silencer of the present invention, in which a tubular member 46 made of, for example, a heat insulating material is press-fitted into the exhaust pipe 3, and the diaphragm 51 is inserted into the tubular member 46. 1 is slidably arranged, and the housing 40 of FIG. 1 is divided into two parts in a plane perpendicular to the axis, and the first case 41 and the second case
The case 42 is divided. The first case 41 has an outer cylinder portion 41a and a wall portion 41c, which correspond to the large diameter portion 40a and the wall portion 40d of the housing 40 in the embodiment of FIG. 1, respectively, and form an enclosure for the sound wave output device 5. ing.

An outer peripheral step portion 41d is formed on the outer periphery of the open end of the outer cylindrical portion 41a, and the bellows 45 is joined thereto, and then the second case 42 is joined. The second case 42 is a tubular body composed of a small-diameter portion 42b and an inclined portion 42a that is continuous with the small-diameter portion 42a and has an outer diameter that gradually increases. The mixer (mixing part) including the outlet 3a of the exhaust pipe 3 is joined to the part 41d to form a shell as shown in FIG.

Thus, in this embodiment, the first case 41 is made of aluminum, for example, and the second case 42 is made of aluminum.
By forming the synthetic resin or the like of a material different from that of the first case 41, it is possible to reduce the weight and the cost. Furthermore, since the bellows 45 can be disposed in the first case 41 after the sound wave output device 5 is housed in the sound wave output unit, the sound wave output unit can be configured easily, and the size of the sound wave output unit can be increased according to the type of vehicle to which it is applied. , Various second cases 4 with different shapes
Two can be joined.

[0024]

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 gap formed on at least one of the inner peripheral side and the outer peripheral side of the vibration member is closed by the closing member, and the sound wave output side of the vibration member is formed. Since the mixing of the sound wave generated on the opposite side with the output sound wave is prevented, the desired output sound wave can be interfered with the exhaust sound, and stable silencing performance can be secured.

In the above active silencer, in which the closing member is formed of bellows, it is easy to mount,
The gap can be reliably closed without hindering the vibration action of the vibration member.

Further, in the above-mentioned active silencer, in which the closing member is composed of the cylindrical spacer, the diaphragm can be slidably supported with respect to the spacer, so that a stable vibration action is obtained. Can be secured.

[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.

FIG. 5 is a cross-sectional view of 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 43, 45 Bellows (blocking member) 50 Driving device 51 Vibration plate (vibrating member)

Claims (3)

[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, the active silencer being arranged around the exhaust pipe and vibrating in an axial direction of the exhaust pipe. A sound wave output device having an annular vibrating member for supporting the sound wave output device and a housing for surrounding the sound wave output device and supporting the exhaust pipe, and at least one side of an inner peripheral side and an outer peripheral side of the vibrating member. An active silencer, characterized in that a blocking member for blocking the formed gap is provided. 2. The active silencer according to claim 1, wherein the closing member is an annular bellows that is joined to either one of the housing and the exhaust pipe and is joined to the vibrating member. 3. The active silencer according to claim 1, wherein the closing member is a cylindrical spacer interposed between any one of the housing and the exhaust pipe and the vibrating member. vessel.