JPH0674035A - Active muffler - Google Patents

Abstract

PURPOSE:To enable proper discharge of consensed water which is discharged from an exhaust pipe in an active muffler provided with a soundwave output device arranged in the vicinity of an outlet of the exhaust pipe and a housing to surround it. CONSTITUTION:A soundwave output device 5 which has an oscillating member 51 and is arranged in the vicinity of an outlet of an exhaust pipe 3. Also, a housing 40 surrounding the soundwave output device 5 and an outlet of the exhaust pipe 3, forming a chamber opened in the direction of the outlet of the exhaust pipe 3 is provided. A drain port 40e is formed in the housing 40, whose port 40e is communicated with a space inside the chamber of the housing 40 and opened on a lower side in respect to the exhaust pipe 3. Interference of the soundwave having a phase opposite to exhaust noise is carried out thereto by means of the soundwave output device 5 for eliminating the noises.

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 In this device, the outlet of the exhaust pipe and the opening of the housing are on the same plane, but the outlet of the exhaust pipe is located in the housing in order to ensure a wide range of noise reduction effect from the outlet of the exhaust pipe. In general, a microphone is arranged between the opening of the housing and the outlet of the exhaust pipe.

However, if the outlet of the exhaust pipe is located inside the housing, the corrosive condensed water discharged from the outlet of the exhaust pipe together with the exhaust gas will drip into the housing. Depending on the situation, this condensed water may collect in the housing and erode the housing. Further, the condensed water accumulated in the housing may reach the sound wave output device and erode the sound wave output device.

Therefore, the present invention is an active silencer having a sound wave output device disposed near the outlet of an exhaust pipe and a housing surrounding the sound wave output device, so that condensed water discharged from the exhaust pipe can be appropriately discharged to the outside of the housing. The purpose is to be able to discharge.

[0006]

In order to achieve the above object, the present invention provides a vibration control system for 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 that has a member and is disposed near the outlet of the exhaust pipe, and a housing that surrounds the sound wave output device and the outlet of the exhaust pipe and defines a chamber that opens in the outlet direction of the exhaust pipe. A drain hole communicating with the inside of the housing and opening on the lower side of the exhaust pipe is formed in the housing.

In the active silencer, a first case for supporting the housing on the exhaust pipe and surrounding the sound wave output device, and a first case joined to the first case in the sound wave output direction of the vibrating member are provided. A second case that defines an opening chamber is provided, and a recess is formed in a joint portion on a lower side of the exhaust pipe on at least one side of the first case and the second case. The drain hole may be formed below the exhaust pipe when the first case and the second case are joined.

Further, with respect to the concave portion formed on one side of the first case and the second case, a flange portion extending in the axial direction with a predetermined gap in the radial direction is provided in the first case and the case. A connecting member that is formed on the other side of the second case and communicates with the inside of the second case between the drain hole and the flange when the first case and the second case are joined. A passage may be formed.

[0009]

In the active silencer having the above-mentioned 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 and the exhaust sound. And is discharged 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 is output to the inside of the housing, which cancels out the exhaust sound. In this case, the condensed water is discharged from the exhaust pipe together with the exhaust gas and drops into the housing, but the condensed water is discharged to the outside through the drain hole and does not accumulate in the housing.

[0010]

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 includes a sound wave output device 5 supported by an exhaust pipe 3 and a housing 40. The housing 40 includes a large diameter portion 40a, a small diameter portion 40b, and a large diameter portion 40a. The inclined portion 40c between and the large diameter portion 40a
The acoustic wave output device 5 is housed in the large-diameter portion 40a, which is a tubular body made of aluminum, synthetic resin, or the like, which is formed of a wall portion 40d that closes the wall and is fixed to the exhaust pipe 3. When the housing 40 is supported by the exhaust pipe 3 near the connecting portion of the inclined portion 40c with the large diameter portion 40a, the exhaust pipe 3
On the other hand, a drain hole 40e is formed in the lower portion.

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. Although the diaphragm 51 of this embodiment has an annular shape, it may have a conical shape having a hole at the center. Sound wave output device 5
The drive device 50 side of the large diameter portion 40 of the housing 40 described above.
A so-called enclosure is surrounded by a, and the drain hole 40e is formed below the inclined portion 40c via 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.

On the other hand, condensed water is discharged from the exhaust pipe 3 together with the exhaust gas and drops into the housing 40 to form the small diameter portion 40.
From b to the large diameter portion 40a through the inclined portion 40c. However, as shown in FIG. 1, the drain hole 40e is formed in this portion.
Therefore, the condensed water is discharged to the outside through the drain hole 40e and is not accumulated in the housing 40. Therefore, the housing 40 is not likely to be corroded by the condensed water. Further, even if rainwater or the like flows in through the opening of the housing 40, it is discharged to the outside through the drain hole 40e.

FIGS. 3 and 4 show another embodiment of the active silencer of the present invention, in which 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 first case 41. It is divided into two cases 42. That is, as shown in FIG. 3, the active silencer 4 has a sound wave output device 5 housed in a housing composed of a first case 41 and a second case 42. 5 is supported 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 the axial ends of both of them. It has a closed shape. The flange portion 4 is provided on the other axial end of the outer tubular portion 41a.
1d is formed. In the present embodiment, these outer cylinder portions 41
The a, the inner cylinder portion 41b, the wall portion 41c, and the flange portion 41d are integrally formed of aluminum, for example.
The first case 41 is joined to the exhaust pipe 3 via a bracket 43. That is, the bracket 43 is previously attached to the exhaust pipe 3.
Are fixed by, for example, welding, and the first case 41 is connected to the bracket 43 by bolts and nuts 44, so that the assembly is easy.

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 between them,
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 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. The small diameter portion 42 of the second case 42
A residual sound detector 6 is provided at b.

The flange portion 42d of the second case 42 is formed with a recess 42e in a portion on the lower side with respect to the exhaust pipe 3, and the first case 41 and the second case are formed as described above. When joined, a drain hole is formed on the lower side of the exhaust pipe 3. Thus, according to this embodiment, it is possible to form the drain hole at an appropriate position without separately forming the hole.

FIG. 5 shows still another embodiment of the present invention. An outer peripheral step portion 41e is formed on the outer periphery of the opening end of the outer cylindrical portion 41a of the first case 41. Further, the large diameter portion 42a of the second case 42 is tubular and is configured such that the outer peripheral step portion 41e of the first case 41 is fitted inside thereof. The large diameter portion 42a of the second case 42 is partially cut off at its outer periphery on the lower side of the exhaust pipe 3 to form a recess 42f. Thus, the outer peripheral step portion 41 is opposed to the recess 42f with a predetermined gap in the longitudinal direction and extends in the axial direction.
The collar portion 41f is constituted by e.
A communication passage that communicates the inside of the second case 42 with the outside is formed between f and the recess 42f, and this functions as the drain hole. According to the present embodiment, the condensed water from the exhaust pipe 3 or the rainwater flowing in from the opening of the small diameter portion 42b of the second case 42 is discharged through the drain hole between the collar portion 41f and the recess 42f. However, since splashes of rainwater and the like that enter from the outside through the drain holes are blocked by the collar portion 41f, the inflow into the second case 42 is blocked.

[0023]

Since the present invention is configured as described above, it has the following effects. That is, the housing of the active silencer of the present invention is formed with a drain hole that opens downward with respect to the exhaust pipe, and the condensed water discharged together with the exhaust gas is discharged to the outside through the drain hole. Since it does not collect in the housing, it is possible to prevent corrosion of the housing and the sound wave output device and ensure good durability.

When the housing is provided with the first case and the second case, since the drain hole is formed in the joint when the two cases are joined, the hole is formed. The manufacturing process is easy because there is no need for the step of performing. Further, both cases can be made of different materials, and for example, the second case can be made of synthetic resin to reduce the weight. Furthermore, since the sound wave output device can be housed in the first case to configure the sound wave output unit, the assembly is easy, and the various second case different in size and shape depending on the type of vehicle to which it is applied. Can also be joined.

In the active muffler further having a collar formed on the first case, it is necessary to prevent rainwater or the like from flowing into the second case from the outside through the drain hole. You can

[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 bottom view of a part of another embodiment of the active silencer of the present invention.

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

[Explanation 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 40 Housing 40e Drain Hole 41 First Case 41f Collar 42 Second Case 42e Recessed portion 50 Drive device 51 Vibration plate (vibration 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, and a sound wave output having a vibrating member and disposed near an outlet of the exhaust pipe. And a housing that surrounds the sound wave output device and the outlet of the exhaust pipe and defines a chamber that opens in the exhaust gas discharge direction of the exhaust pipe, and communicates with the interior of the housing and connects to the exhaust pipe. On the other hand, an active silencer characterized in that a drain hole that opens downward is formed in the housing. 2. The housing includes a first case which is supported by the exhaust pipe and surrounds the sound wave output device, and a chamber which is joined to the first case and opens in the sound wave output direction of the vibrating member. A second case that forms a concave portion is formed in a joint portion on a lower side of the exhaust pipe on at least one side of the first case and the second case.
2. The active silencer according to claim 1, wherein the drain hole is formed below the exhaust pipe when the case and the second case are joined. 3. A collar portion extending axially with a predetermined gap in the radial direction with respect to the recess formed in one side of the first case and the second case, the first case and the A connecting member that is formed on the other side of the second case and communicates with the inside of the second case between the drain hole and the flange when the first case and the second case are joined. The passage is formed so that the passage is formed.
The described active silencer.