JPH06323122A - Noise eliminator - Google Patents

Abstract

PURPOSE:To provide a noise eliminator which eliminates pulsation noise from an exhaust pipe and helps down-sizing. CONSTITUTION:When a vibration plate 40 is vibrated by a voice coil 42e, a compressional wave is propagated toward an exit 31r in a case 3. The compressional wave has a sound pressure substantially equal to that of pulsation noise from an exhaust pipe 1 and a phase substantially opposite to that of the pulsation noise. The pressure wave plane 40c of the vibration plate 40 is peripherally circulated one round on the outer periphery of the exhaust pipe 1 and so the pressure distribution of the compressional wave arising on the vibration plate 40 is peripherally uniformed on the outer periphery of the exhaust pipe 1. Good interference between the pulsation noise from the exhaust pipe 1 and the compressional wave on the vibration plate 40 occurs in the axial center direction as well as the peripheral direction of the exhaust pipe 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer. This device can be applied, for example, to muffle noise caused by equipment such as an internal combustion engine, a pump, a compressor and the like.

[0002]

2. Description of the Related Art In recent years, a device for silencing noise has been developed as a silencing device by utilizing interference of compressional and dense pressure waves. In an internal combustion engine, since exhaust gas is intermittently discharged from an exhaust valve of the internal combustion engine, the exhaust gas is discharged with pulsating noise. Such pulsating noise causes noise. Therefore, as a device that silences the pulsating sound, a device that includes a detector that detects the pulsating sound, a speaker, and a control device that controls the speaker according to a signal from the detector has been developed. 2-503219). In this device, when the detector detects the density of the pulsating sound, a pressure wave having a phase opposite to the density of the pulsating sound is generated from the speaker. Then, an interference action of both occurs, and noise due to pulsating sound is reduced or eliminated.

FIG. 1 shows a muffling device applying this principle.
As shown in FIG. 4 and FIG. 15, the exhaust pipe 100 and the exhaust pipe 100 are covered with the outer periphery of the tip end portion of the exhaust pipe 100.
Case 200 forming a chamber 201 communicating with the passage 101 of
And a plurality of loudspeakers 300 arranged in the chamber 201 of the housing 200 are known (Shokai Sho 4-
129820). In this device, as shown in FIG. 14, the axis of the speaker 300 is arranged substantially parallel to the axis of the exhaust pipe 100, and the propagation direction of the compression-dense pressure wave generated from the speaker 300 is the exhaust gas of the exhaust pipe 100. It corresponds to the flowing direction of. In this structure, as can be understood from FIG. 15, a space S is provided between the adjacent speakers 300. When the pulsating sound is discharged together with the exhaust gas from the exhaust pipe 100, a compression / dense pressure wave having a phase opposite to that of the pulsation sound is generated from the speaker 300, whereby a compression / dense pressure wave having an opposite phase is passed through the passage of the exhaust pipe 100. The pulsating sound emitted from 101 merges with each other to cause interference, and noise due to the pulsating sound is reduced or eliminated.

The above publication also discloses a silencer in which the axes of a plurality of speakers 400 are arranged in the radial direction with respect to the axis of the exhaust pipe 100, as shown in FIG. . Also in this case, the speakers 4 that are adjacent to each other are similarly provided.
Between 00 is a space. Further, as a muffler having another structure, as shown in FIG. 17, a passage 5 through which pulsating sound passes.
Exhaust pipe 500 having 01, a casing 600 forming a chamber 601 through which an air flow flows, an inner surface of the casing 600 and the exhaust pipe 5
Sound absorbing materials 700 and 701 held on the outer surface of the chamber 00 and the chamber 6
01, the speaker 80 arranged in the housing 600 so as to face the inside
Is known (Japanese Patent Laid-Open No. 4-1839).
No. 12). Even in this case, the compression / dense pressure wave having a phase substantially opposite to that of the pulsation sound of the exhaust pipe 500 is generated from the speaker 800, and the noise due to the pulsation sound is reduced or eliminated. Further, the air flow flows through the chamber 601 of the housing 600,
Since the exhaust gas concentration in the inside decreases, it is advantageous in preventing the erosion of the speaker 800 by the exhaust gas, and at the same time, the speaker 800 can be cooled.

[0005]

By the way, in the apparatus shown in FIGS. 14 and 15, since a plurality of loudspeakers 300 are provided in the space S, the area of the space S has an antiphase density. There is no pressure wave generation surface for generating pressure waves. Therefore, the pressure distribution of the compression phase compression wave having the opposite phase generated in the speaker 300 is not uniform in the circumferential direction of the outer circumference of the exhaust pipe 100 on the virtual plane orthogonal to the axis of the exhaust pipe 100. Therefore, the interference phenomenon is not satisfactorily obtained, and the vibration reducing effect is not always sufficient.

In the apparatus shown in FIG. 16, the speaker 40
Since the axis of 0 is arranged in the radial direction with respect to the axis of the exhaust pipe 100, the compression phase pressure waves of opposite phase generated from the speaker 400 and the pulsating sound from the exhaust pipe 100 are less likely to interfere with each other. Therefore, the vibration reduction effect is not always sufficient. Similarly, the device shown in FIG. 17 does not always have sufficient vibration reduction effect.

The present invention has been made in view of the above situation, and an object thereof is to make it possible to make a compressional pressure wave having a phase opposite to that of the pulsating sound discharged from the pipe body continuous in the circumferential direction of the pipe body, As a result, interference is improved, and it is an object of the present invention to provide a silencer capable of further improving the silencing performance. Another object of the present invention is to provide a muffling device which is advantageous in reducing the size and weight of the entire device, because the device can be downsized while ensuring the area of the pressure wave generating surface.

[0008]

DISCLOSURE OF THE INVENTION The muffler of the present invention comprises a pipe body having a passage through which pulsating sound passes from one end to the other end, and a chamber covering the outer periphery of the pipe body and communicating with the passage of the pipe body. A holding part to be formed, and a vibrating body that is disposed inside the holding part and that silences the pulsating sound discharged from the pipe body by merging the compression and compression pressure wave of a phase substantially opposite to that of the pulsating sound of the pipe body. The vibrating body is configured such that the vibrating body continuously makes one round in the circumferential direction around the outer circumference of the pipe body and has a pressure wave generating surface in the vibration direction in the passage direction of the pulsating sound in the passage of the pipe body. It is what

The tubular body has a passage through which the pulsating sound passes from one end to the other end. The holding portion forms a chamber that covers the outer periphery of the pipe and communicates with the passage of the pipe. The holder can be a housing. The vibrating body generates a compressional pressure wave having a phase substantially opposite to the compressional density of the pulsating sound discharged from the pipe body. The vibrating body can be configured using a vibrating plate, a film body, or the like, and can be configured using a vibrating plate or a film body used in a speaker. The material of the vibrating plate, the film body, etc. can be appropriately selected according to the place of use, etc., and the metal plate, the glass fiber aggregate, the paper,
Cloth, plastic, ceramics, etc. can be used, but when heat resistance is required, glass fiber aggregates, metals such as stainless steel, and ceramics are preferable.

The pressure wave generating surface of the vibrating body is constructed so as to continuously make one turn around the outer circumference of the tubular body in the circumferential direction. When holding the vibrating body in the holding portion, it is necessary to vibratably hold the vibrating portion of the vibrating body. In this sense, a flexible glass fiber aggregate, a spring member, or the like can be employed. The drive source of the vibrating body is appropriately selected in consideration of the frequency and sound pressure of the pulsating sound, but an electromagnetic actuator using a voice coil, a hydraulic actuator using a cylinder, or a pneumatic actuator can be adopted. Further, as the drive source, a piezoelectric element or a piezoelectric actuator using a motion enlarging mechanism for enlarging the operation of the piezoelectric element can be adopted in addition to the piezoelectric element. Further, a mechanism for hydraulically magnifying the displacement of the piezoelectric actuator and a mechanism for hydraulically magnifying the displacement of the electromagnetic actuator can also be adopted. The number of these driving sources can be set according to the area of the vibrating portion of the vibrating body.

[0011]

In the device of the present invention, when the vibrating body is operated, the compression and compression pressure waves are generated from the pressure wave generating surface of the vibrating body. The compressional pressure wave has a phase substantially opposite to the compressional density of the pulsating sound discharged from the pipe body. In the device of the present invention, the pressure wave generation surface of the vibrating body is configured to continuously make one round in the circumferential direction on the outer circumference of the tube body, so that the compression-dense pressure waves of opposite phase are continuously generated in the circumferential direction of the tube body. To do. Therefore, the pressure distribution of the antidense and dense pressure waves generated in the vibrating body is made uniform in the circumferential direction of the outer circumference of the pipe body on the virtual plane orthogonal to the axis of the pipe body.

Moreover, the compressional and dense pressure waves propagate basically in the same direction as the passing direction of the pulsating sound. Therefore, in the device of the present invention, the pulsating sound discharged from the tubular body and the compressional pressure wave of the opposite phase are likely to interfere with each other, and the silencing efficiency is improved.

[0013]

【Example】

(First Embodiment) Hereinafter, a first embodiment of the device of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. As can be understood from FIG. 1, the exhaust pipe 1 as a pipe body has a passage 1a. From the one end to the other end of the exhaust pipe 1, the pulsating sound together with the exhaust gas passes through the passage 1a in the direction of the arrow A1 and is discharged from the discharge port 1c of the exhaust pipe 1.

The casing 3 as a holding portion covers the outer circumference of the exhaust pipe 1. The housing 3 is formed of a large diameter portion 3a and a small diameter portion 3b, and a chamber 3f is formed inside thereof. The outlet 31r of the small diameter portion 3b and the outlet 1c of the exhaust pipe 1 communicate with each other.
The vibrating body 4 is composed of a ring-shaped vibrating plate 40 having one pressure wave generating surface 40c that continuously makes one revolution in the outer circumferential direction of the exhaust pipe 1, and a drive source 42 that vibrates the vibrating plate 40. It is configured. The inner peripheral portion of the diaphragm 40 is vibratably supported on the outer peripheral surface of the exhaust pipe 1 by a small-diameter ring-shaped small-diameter support portion 40h, and the outer peripheral portion of the diaphragm 40 is attached to the inner surface of the housing 3 with a large-diameter ring-shaped large diameter. It is oscillatably supported by the support portion 40i. The small diameter support portion 40h and the large diameter support portion 40i are formed by using an aggregate of glass fibers in consideration of heat resistance and the like. The vibrating plate 40 is also formed by using an aggregate of glass fibers in consideration of heat resistance and the like.

Due to the vibrating plate 40, the chamber 3f inside the housing 3
Is partitioned into a first chamber 3m and a second chamber 3n.
The chamber 3m and the second chamber 3n are not in communication with each other. The drive source 42 includes a ring-shaped first yoke 42 a and a locking portion 42.
The ring-shaped second yoke 42 held by the housing 3 by x.
b, a ring-shaped magnet 42c sandwiched between the first yoke 42a and the second yoke 42b, a magnetic path forming cylinder 42d which is a part of the second yoke 42b, and a gap between the first yoke 42a. And a voice coil 42e.
The magnet 42c facing the yokes 42a and 42b has an axial end surface as a magnetic pole, and the magnet 42c, the first yoke 42a, the second yoke 42b, and the magnetic path forming cylinder 42d form a loop-shaped magnetic path. The voice coil 42e is the magnetic path forming cylinder 4
It is movable along arrow 2d in the directions of arrow B1 and arrow B2. The voice coil 42e is located in the gap between the first yoke 42a and the second yoke 42b, and is arranged so as to block the magnetic path. One end of the voice coil 42e is the diaphragm 40
, And the other end of the voice coil 42e is free and has no connection.

When an alternating current is applied to the voice coil 42e, due to the reversal of the current, forces having opposite directions act alternately on the voice coil 42e according to Fleming's law, and the voice coil 42e causes the arrow B1 to move. Direction and the arrow B2 direction alternate. As a result, the vibrating plate 40 vibrates in the same direction, and the pressure wave generating surface 40c of the vibrating plate 40 generates a compression-dense pressure wave, which is discharged from the outlet 31r of the housing 3.

In this embodiment, the frequency of the alternating current supplied to the voice coil 42e can be set to 20 to 500 Hz, and the frequency of the voice coil 42e can be set to 20 to 500 Hz. Now, in this embodiment, the exhaust gas discharged from the exhaust valve of the internal combustion engine passes through the passage 1a of the exhaust pipe 1 together with the exhaust sound and is discharged from the discharge port 1c of the exhaust pipe 1. At this time, the diaphragm 40 of the vibrating body 4 vibrates in the directions of the arrows B1 and B2, and the compression-dense pressure wave propagates inside the housing 3 toward the outlet 31r. Here, the compression and compression pressure wave generated by the vibration plate 40 has substantially the same sound pressure as the pulsating sound discharged from the exhaust pipe 1 and a phase substantially opposite to that of the pulsating sound. As a result, the pulsating sound discharged from the exhaust pipe 1 interferes with the compression phase pressure waves of opposite phase generated by the vibration plate 40 and cancel each other out. Therefore, the noise due to the pulsating sound discharged from the exhaust pipe 1 is reduced or eliminated.

As described above, in the present embodiment, the pressure wave generating surface 40c of the vibrating plate 40 is constructed so as to continuously make one revolution in the circumferential direction around the outer periphery of the exhaust pipe 1, so that the anti-phase effect which produces the noise suppressing effect is obtained. The dense and dense pressure waves of are continuously generated in the entire circumference in the circumferential direction of the exhaust pipe 1, and therefore, are made uniform in the circumferential direction of the outer circumference of the exhaust pipe 1 on a virtual plane orthogonal to the axis of the exhaust pipe 1. Moreover, the compressional pressure wave exits inside the housing 3 at the outlet 31r.
Propagates in the same direction as the pulsating sound of the exhaust pipe 1. Therefore, the pulsating sound from the exhaust pipe 1 and the compression-dense pressure wave from the vibration plate 40 satisfactorily interfere with each other in the vicinity of the outlet 31r both in the axial direction of the exhaust pipe 1 and in the circumferential direction of the exhaust pipe 1. Cancel each other out.

Therefore, the sound deadening performance is improved as compared with the conventional device shown in FIGS. In the conventional device shown in FIGS. 14 and 15, as described above, the adjacent speaker 300 is installed.
This is because the space S is formed between them and the pressure wave generation surface is not continuous in the circumferential direction of the exhaust pipe. In this embodiment in which the silencing performance is improved as described above, in FIGS.
It is possible to reduce the outer diameter dimensions of the diaphragm 40 and the pressure wave generating surface 40c while maintaining the same level of silencing function as that of the conventional device shown in FIG. 1, which is advantageous for downsizing and weight saving of the device.

Further, in the present embodiment, the diaphragm 40 and the diaphragm 4
A ring-shaped small-diameter support portion 40h that supports 0 for vibration,
Since both the ring-shaped large-diameter support portions 40i are formed by using an aggregate of glass fibers, heat resistance is ensured,
This is advantageous in avoiding thermal effects due to the temperature of the exhaust gas. Therefore, the vibration performance of the diaphragm 40 is ensured for a long period of time. In addition, the small diameter support portion 40h and the large diameter support portion 40i
Is flexible, it is possible to suppress the vibration of the diaphragm 40 from being transmitted to the housing 3 and the exhaust pipe 1.

(Example of Application) FIG. 4 shows an example of application to an internal combustion engine of a vehicle. In this example, as shown in FIG.
Sensor 701 installed on the exhaust valve side of 00 and a second detection microphone 702 installed on the discharge port 1c side of the exhaust pipe 1.
And the signal of the pressure sensor 701 and the second detection microphone 702.
And a control device 800 to which the signal is input. The control device 800 is provided with a circuit that controls the frequency, magnitude, and phase of the current supplied to the voice coil 42e to control the operation of the voice coil 42e.

In this example, when the pressure sensor 701 detects the pulsating pressure of the exhaust gas from the internal combustion engine 700, the detection signal of the pressure sensor 701 is input to the control device 800.
In response to this input signal, the control device 800 actuates the voice coil 42e to vibrate the diaphragm 40 and generate a compression / compression pressure wave. As described above, this compression / dense pressure wave has the same sound pressure and opposite phase to the pulsating sound discharged from the exhaust pipe 1. As a result, the pulsating sound discharged from the exhaust pipe 1 is reduced or eliminated by the interference phenomenon. That is, the noise due to the pulsating sound is silenced.

The degree to which the sound is muted is confirmed by the second detection microphone 702. When the muffling effect is smaller than the predetermined value, the detection signal from the second detection microphone 702 is input to the control device 800, so the control device 800 controls the operation of the voice coil 42e so as to increase the muffling effect. By the way, depending on the number and type of cylinders of the internal combustion engine, if the number of revolutions is within a normal use range of 1000 rpm to 6000 rpm, generally, the exhaust valve of the internal combustion engine is connected to the exhaust pipe 1.
The fundamental frequency f of the pulsating sound of the exhaust gas discharged to
It is estimated to be about 300 Hz (50 to 30 for 6 cylinders)
0Hz, 4 cylinders 33-200Hz).

In this example, the vibrating plate 40 corresponds to the fundamental frequency of the pulsating sound of the exhaust gas discharged from the exhaust pipe 1.
It vibrates at 0 to 300 Hz. (Second Embodiment) A second embodiment of the device of the present invention is shown in FIGS. The structure of this example is basically the same as that of the first embodiment. Therefore, the same reference numerals are given to the parts having the same function. Therefore, in this example as well, the diaphragm 40 having a ring shape having one pressure wave generating surface 40c that continuously makes one round in the circumferential direction on the outer circumference of the exhaust pipe 1 is provided. In order to vibrate the diaphragm 40, a plurality of drive mechanisms 48 held by the housing 3 are used. The drive mechanism 48 may be an electromagnetic actuator type, a piezoelectric drive type, a hydraulic drive type, or a pneumatic drive type. As shown in FIG. 7, the drive mechanisms 48 are arranged at equal intervals in the circumferential direction of the exhaust pipe 1.

When the plurality of drive mechanisms 48 operate in synchronism, the drive shafts 48c of the plurality of drive mechanisms 48 synchronously move alternately in the directions of arrow B1 and arrow B2. As a result, the vibrating plate 40 vibrates in the same direction, and the pressure wave generating surface 40c of the vibrating plate 40 generates a coarse / dense pressure wave. In this example as well, basically the same operational effects as in the first example are obtained, and the pulsating sound from the exhaust pipe 1 is silenced. In this example, a plurality of drive mechanisms 48
Operate in synchronization with each other, so that uniform operability is ensured in each part of the diaphragm 40.

(Third Embodiment) FIG. 8 shows a third embodiment of the device of the present invention. The configuration, operation and effect of this example are similar to those of the first example. Therefore, basically, the same reference numerals are given to the parts having the same function. However, the cross section of the housing 3 has an oval shape, and the diaphragm 49 has an oval shape so as to fit the inner peripheral surface of the housing 3, and the outer periphery of the exhaust pipe 1 is circumferentially arranged. It has a pressure wave generating surface 49c that makes one round continuously. The large-diameter support portion 49i has an oval ring shape corresponding to the shape of the diaphragm 49.

(Fourth Embodiment) A fourth embodiment of the device of the present invention is shown in FIGS. The structure of this example is basically the same as that of the second embodiment. Therefore, the same reference numerals are given to the parts having the same function. However, two exhaust pipes 1 are arranged side by side. The diaphragm 70 is a small-diameter ring-shaped small-diameter support portion 7.
0h, it is vibratably supported on the outer peripheral surface of each exhaust pipe 1,
The outer peripheral portion of the diaphragm 70 has a large-diameter ring-shaped large-diameter support portion 70i.
Is vibratably supported on the inner surface of the housing 3.

Also in this example, as can be understood from FIG.
The pressure wave generating surface 70c of the vibrating plate 70 is provided on the entire circumference of the outer circumference of each exhaust pipe 1, and continuously makes one circumference of the outer circumference of each exhaust pipe 1 in the circumferential direction. Further, as can be understood from FIG. 9, a drive mechanism 72, a drive mechanism 73 for vibrating the diaphragm 70,
The drive mechanism 74 is arranged in parallel along the major axis direction of the diaphragm 70. The drive mechanism 73 is held in the housing 3 by a locking arm 73x.

In this example, when the drive mechanisms 72, 73, 74 operate in synchronism, the drive shafts 72a, 73a, 74a of the drive mechanisms 72, 73, 74 synchronously alternate in the directions of arrow B1 and arrow B2. Moving. As a result, the vibrating plate 70 vibrates in the same direction, and the pressure wave generating surface 70c of the vibrating plate 70 generates a compression-dense pressure wave, which is discharged from the outlet 31r of the housing 3. In this example, since the drive mechanism 72, the drive mechanism 73, and the drive mechanism 74 operate in synchronization, even if the diaphragm 70 has a large area, uniform operability in each part of the diaphragm 70 is ensured.

In this example as well, basically the same operation and effect as in the second example can be obtained, and the pulsating sound of the exhaust pipe 1 is silenced. (Fifth Embodiment) FIG. 12 shows a fifth embodiment of the device of the present invention. The structure of this example is basically the same as that of the first embodiment. Therefore, the same reference numerals are given to the parts having the same function. However, the connecting cylinder 18 is connected to the outer peripheral side of the exhaust pipe 1 by a connecting arm 18r substantially coaxially.
The first chamber 3m and the second chamber 3n of the housing 3 by the passage 18s of
And are in communication with each other.

This example utilizes the Helmholtz resonance principle, and utilizes the phenomenon that the air in the second chamber 3n and the air in the communication passage 18s resonate in a specific frequency range, that is, a resonance frequency range. According to this principle, when the present device is used in a frequency range higher than the resonance frequency range, the compression / compression pressure wave that emerges in the direction of arrow B1 from the front surface of the vibrating body 40 through the first chamber 3m toward the outlet 31r. And the phase of the compressional-pressure pressure wave that is emitted from the rear surface of the vibrating body 40 and is amplified by resonance and that is output from the communication passage 18s in the direction of the arrow B1 have the same phase, and the compressional-pressure pressure wave discharged from the outlet 31r of the housing 3 is Can be expected to increase the sound pressure. Therefore, the efficiency of obtaining the compressional and dense pressure waves for noise reduction is improved, which is advantageous for downsizing of the vibrating body 40, and thus for downsizing of the device.

The volume of the second chamber 3n is V2, and the communication passage 18
If the volume of s is V3, the resonance frequency range is basically V
It is considered that the value of V3 and the value of V2 affect the volume of V3, so that a desired resonance frequency range can be obtained.
The volume of V2, that is, the axial length and inner diameter of the through cylinder 18, the axial length and inner diameter of the housing 3, and the like are set. In the internal combustion engine of a vehicle, the frequency of the pulsating sound discharged from the exhaust pipe 1 of the internal combustion engine is generally about 30 to 300 Hz as described above, so the resonance frequency range of this device is 30 Hz. The volume of V3 and the volume of V2 are set so as to be about the same.

(Sixth Embodiment) FIG. 13 shows a sixth embodiment of the device of the present invention. The configuration, operation and effect of this example are basically the same as those of the fifth example. In this example, the second communication tube 19 is connected to the outer peripheral side of the exhaust pipe 1 by a connecting arm 19r substantially coaxially. The first chamber 3m and the second chamber 3n of the housing 3 communicate with each other through the passage 19s of the second communication cylinder 19. Also in this example, the air in the second chamber 3n resonates with the air in the communication passage 19s in a specific frequency range, and the sound pressure of the compression-pressure wave discharged from the outlet 31r of the housing 3 is increased.

Also in this example, the volume of the second chamber 3n is set to V
5, and the volume of the communication passage 18s is V6, the volume of V6 and the volume of V5 are set so that a desired resonance frequency range can be obtained. Further, in this example, the cooling cylinder 78 is connected to the outer peripheral surface of the exhaust pipe 1 substantially coaxially by a connecting arm 78r. In this example, the outside air is sucked into the cooling cylinder 78 by the negative pressure of the exhaust gas, or the outside air is cooled by the traveling of the vehicle.
Since the inside of the chamber 3f of the housing 3 is cooled,
As a result, various components such as the diaphragm 40 and the voice coil 42e arranged inside the chamber 3f are cooled. Therefore,
The durability of these parts is improved, which is advantageous in terms of stabilization and durability of the entire device. Furthermore, since the housing 3 and the exhaust pipe 1 are connected via the connecting arm 78r, heat transfer from the exhaust pipe 1 to the housing 3 is suppressed, which is further advantageous in preventing the high temperature of the chamber 3f.

(Other Examples) In the above example, the housing 3 has a cylindrical shape, but the shape is not limited to this and may have a rectangular tube shape. Further, in the above-mentioned example, the case is applied to the exhaust pipe 1 of the internal combustion engine, but the invention is not limited to this and may be applied to the intake pipe of the internal combustion engine.
Also, not only internal combustion engine, but also the exhaust pipe and intake pipe of the engine,
It may be applied to other devices or other institutions. Further, in the above-described example, the cross-sectional shape of the vibration plate 40 is a flat plate shape, but the shape is not limited to this and may be a conical shape.

In addition, the apparatus of the present invention is not limited to the above-mentioned embodiment and shown in the drawings, but may be implemented by appropriately changing it within a range not departing from the gist.

[0037]

According to the apparatus of the present invention, since the pressure wave generating surface of the vibrating body is provided so as to go around the outer circumference of the pipe body from which the pulsating sound is discharged, the coarse and dense pressure having a phase opposite to that of the pulsating sound is provided. The waves can be made continuous in the circumferential direction of the pipe body, and the sound deadening performance can be further improved as compared with the conventional device.

Further, according to the device of the present invention, since the silencing performance is improved, it is advantageous to reduce the size and weight of the entire device while ensuring the required silencing performance.

[Brief description of drawings]

FIG. 1 is a sectional view of an apparatus according to a first embodiment.

FIG. 2 is a view taken along line II-II of FIG.

FIG. 3 is a view taken along line III-III in FIG.

FIG. 4 is a schematic diagram showing a control system equipped with an internal combustion engine, an exhaust pipe, and a control device.

FIG. 5 is a sectional view of the device according to the second embodiment.

FIG. 6 is a view taken along line VI-VI in FIG.

FIG. 7 is a view taken along line VII-VII in FIG.

FIG. 8 is a sectional view of the device in different directions according to the third embodiment.

FIG. 9 is a cross-sectional view of the device according to the fourth embodiment.

10 is a view as seen from a direction indicated by an arrow X-X in FIG.

11 is a view taken along the line XI-XI of FIG.

FIG. 12 is a cross-sectional view of the device according to the fifth embodiment.

FIG. 13 is a sectional view of the apparatus according to the sixth embodiment.

FIG. 14 is a cross-sectional view of a device according to a conventional example.

FIG. 15 is a view taken along the line WW of FIG.

FIG. 16 is a cross-sectional view of an apparatus according to another conventional example.

FIG. 17 is a cross-sectional view of an apparatus according to another conventional example.

[Explanation of symbols]

In the figure, 1 is an exhaust pipe, 1a is a passage, 3 is a housing (holding portion),
3f is a chamber, 4 is a vibrating body, 40 is a diaphragm, 40c is a pressure wave generating surface, 42 is a drive source, and 42e is a voice coil.

Claims (1)

[Claims] 1. A tubular body having a passage through which pulsating sound passes from one end to the other end, a holding portion which covers the outer periphery of the tubular body and forms a chamber communicating with the passage of the tubular body, and the holding portion of the holding portion. A vibrating body that is disposed in a room and that silences a compressional pressure wave having a phase substantially opposite to that of the pulsating sound discharged from the pipe body by merging with the pulsating sound of the pipe body. A silencer characterized in that the outer circumference of the pipe is continuously made one round in the circumferential direction, and the vibration direction has a pressure wave generating surface in the passage direction of the pulsating sound in the passage of the pipe. .