JPH0988546A - Muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler which can be manufactured in approximately the same size as the conventional muffler, and can reduce a noise to a large extent without lowering the output of an engine. SOLUTION: In a main muffler 3 arranged at near the outlet opening of an exhaust gas pipe 2, an air chamber 7 and a packed space 8 are formed by a casing 5 and a partitioning wall 16, and speakers 6, 6 are arranged to be directed to the air chamber 7. A sound part 9 is concentrically arranged with the exhaust gas pipe 2, and one end of the sound port 9 is communicated with the air chamber 7. The speakers 6, 6 receive a noise reducing signal (y) from a noise reducing signal generator 14 so that a resonance system formed of the stiffness of the air chamber 7 and the air mass of the sound port 9 is driven, and a noise reducing acoustic wave whose amplitude is the same as a noise and which is a reverse phase is generated. Noise reducing deviation is detected by a noise reducing deviation detector 13 arranged in the vicinity of the outside of the exhaust gas pipe 2, and the driving of the speaker 6, 6 are controlled so that the noise reducing deviation becomes zero. Hereby, this muffler can be manufactured in approximately the same size as the conventional muffler, and can reduce the noise to a large extent without lowering the output of an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer.

[0002]

2. Description of the Related Art As one of conventional silencers, for example, a silencer (so-called muffler) has a structure in which an exhaust pipe is bent, expanded or contracted, so that exhaust resistance is increased and an engine is The output loss of is large. In addition, there is a problem that it is not possible to obtain a sufficient silencing effect for noise in a low frequency region of 100 Hz or less.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and for example, a silencer capable of substantially reducing noise with substantially the same size as a conventional silencer without reducing the output of the engine. The purpose is to provide.

[0004]

[Means for Solving the Problems] The above object is to dispose a sound deadening deviation detecting means in the vicinity of a straight exhaust pipe and to install at least one sound wave generating means in the vicinity of the exhaust pipe.
A closed casing having a closed space formed to close the back of the sound wave generator is formed, an air chamber is provided in front of the sound wave generator, and an acoustic port is installed so as to concentrically surround the exhaust pipe. , One end of which is in communication with the air chamber and the other end of which is in communication with the outside.

Further, for the above-mentioned object, the sound deadening deviation detecting means is arranged near the outside of the straight exhaust pipe, at least one sound wave generating means is installed near the exhaust pipe, and the back of the sound wave generating means is sealed. A closed casing having a closed space is formed, an air chamber is provided in front of the sound wave generating means, and first and second acoustic ports are installed concentrically with the exhaust pipe. One end of the port communicates with the air chamber, one end of the other acoustic port communicates with the closed space, and the other end of each communicates with the outside, the stiffness of the air chamber and the air in the one acoustic port. The sound deadening device is characterized in that a first resonance system is formed by the mass and a second resonance system is formed by the stiffness of the closed space and the air mass of the other acoustic port.

Further, the above-mentioned object is to arrange a sound deadening deviation detecting means in the vicinity of a straight exhaust pipe, to install at least one sound wave generating means in the vicinity of the exhaust pipe, and to arrange air in front of the sound wave generating means. A chamber is provided, which is concentric with the exhaust pipe,
A second acoustic port is installed, one end of one acoustic port communicates with the air chamber, one end of the other acoustic port communicates with the back space of the sound wave generating means, and the other end of each acoustic port communicates with the outside. A first resonance system is formed by the stiffness of the air chamber and the air mass in the one acoustic port, and a predetermined distance from the back space to the opening facing the outside of the other acoustic port is established. And a second resonance system that is determined by the total length of the pipeline.

Further, the above-mentioned object is to arrange a sound deadening deviation detecting means in the vicinity of a straight exhaust pipe and to install at least one sound wave generating means in the vicinity of the exhaust pipe. First and second acoustic ports are installed, one end of one acoustic port communicates with the back space of the sound wave generating means,
One end of the other acoustic port communicates with the front space of the sound wave generating means, and the other end of each acoustic port communicates with the outside, and the two acoustic spaces, the back space and the front space, are connected to the one acoustic port. It is characterized in that two predetermined pipelines leading to the outwardly facing openings of the other acoustic port are bent to be independently formed, and two resonance systems determined by the total length of the pipelines are formed. Achieved by a silencer.

Further, for the above-mentioned object, the sound deadening deviation detecting means is arranged near the outside of the straight exhaust pipe, at least one sound wave generating means is installed near the exhaust pipe, and the back of the sound wave generating means is sealed. A closed casing having a closed space formed so as to form an air chamber in front of the sound wave generating means, an acoustic port is installed in the vicinity of the exhaust pipe, one end of which communicates with the air chamber, And a silencer characterized in that the other end communicates with the outside.

[0009]

According to the invention of claim 1, the sound wave generating means is driven so as to generate a silencing sound wave having the same amplitude as the noise and the opposite phase. The sound-deadening sound wave is muted by interfering with the noise in the vicinity of the opening of the exhaust pipe, and the deviation is detected by the sound-deadening deviation detecting means arranged near the outside of the exhaust pipe. The sound wave generating means is controlled so that the muffling deviation becomes zero at the position. As a result, the exhaust gas path can be made straight while maintaining the same size as the conventional silencer, so that the output loss of the engine can be significantly reduced, and the low-frequency band, which was conventionally difficult, can be reduced. Noise can be efficiently reduced.

According to the third aspect of the present invention, one ends of the first and second acoustic ports that are installed concentrically with the exhaust pipe communicate with the air chamber and the closed space, respectively,
The resonance frequency of the first resonance system formed by the stiffness of the air chamber and the air mass of the first acoustic port, and the resonance frequency of the second resonance system formed by the stiffness of the closed space and the air mass of the second acoustic port. A sound deadening sound wave having two resonance frequencies is generated. This makes it possible to muffle noise in a wide frequency band.

In the invention of claim 5, the first and second acoustic ports are installed as in the invention of claim 3, but the space behind the sound wave generating means bends a predetermined pipe line. The resonance system, which is determined by the total length of this conduit, is
It forms as a resonance system of. That is, the second resonance system uses air column resonance. Further, according to the invention of claim 5, the first resonance system also forms a resonance system utilizing air column resonance, similarly to the second resonance system. According to these inventions, the same effect as the third aspect can be obtained.

Further, in the invention of claim 8, since the acoustic port is installed in the vicinity of the exhaust pipe, the diameter of the sound source is larger than that of the invention of claim 1, but the same operation as in claim 1 is achieved. can get.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a muffler 1 according to a first embodiment of the present invention, in which FIG. 1 is a sectional view of a main muffler 3 mounted near the rear end of an exhaust pipe 2 of an engine or the like. 2 shows a front view thereof. The main silencer 3 of this embodiment has substantially the same shape as the conventional main silencer. Exhaust gas discharged from the engine at a high temperature of about 600 ° C. and having a pressure of 3 to 5 kg / cm ² flows in the straight exhaust pipe 2 in the direction of arrow a toward the open end 2a of the exhaust pipe 2. Although not shown, an auxiliary silencer similar to the conventional one is provided on the upstream side of the exhaust pipe 2 to reduce noise of high frequency components. The sub-muffler is, for example, a resonance type that applies the principle of resonance attenuation, an expansion type that has an expansion chamber in the middle of the exhaust pipe, a sound absorption type that contains a heat-resistant sound absorbing material that absorbs sound wave energy, or these. A composite type combined is used.

The main silencer 3 will be described in detail. As shown in FIG. 2, speakers 6 which are sound wave generating means of the present invention are provided in the vicinity of the exhaust pipe 2 inside a casing 5 having an elliptic cylindrical shape as a whole. Behind the speakers 6 and 6, a partition space 16 and a casing 5 form a closed space 8 having a sufficiently large volume so that the diaphragm of the speaker 6 can move without resistance. In addition, the speakers 6 and 6
One air chamber 7 having a predetermined volume is formed facing the front surface of the. That is, the air chamber 7 and the closed space 8 are annular and communicate with each other on the left and right sides so as to surround the exhaust pipe 2 in FIG. 1. An acoustic port 9 having a length L and concentric with the exhaust pipe 2 is disposed outside the exhaust pipe 2, and one end of the acoustic port 9 is provided in the air chamber 7.
And the other end is on the same line as the end face of the open end 2a of the exhaust pipe 2 and is open to the outside. Further, a net-shaped filter 11 is provided between the end of the acoustic port 9 and the opening end 2a to prevent foreign matters and the like from entering the air chamber 7 from the outside. Furthermore, as shown in FIG. 2, a drain hole 10 and evaporation holes 12 are formed so as to respectively the bottom and top of the air chamber 7 communicating with the outside, the water mixed in the air chamber 7 to the outside I try to discharge it.

In this embodiment, the stiffness of the air determined by the volume of the air chamber 7 and the predetermined air mass determined by the volume of the acoustic port 9 having the length L form an acoustic resonance system called a Kelton type. The resonance frequency is determined to match the frequency component of the main noise emitted from the exhaust pipe 2. In addition, a sound wave having this resonance frequency is generated by the speaker 6, but a dynamic speaker is used as the speaker 6 in this embodiment.

Next, the details of the speaker 6 will be described with reference to FIG. Inside the frame 26 having a plurality of openings 26a formed on the side surface, a diaphragm 21 made of metal such as hyperbolic aluminum, paper, carbon, plastic, ceramic, aramid fiber, glass fiber, etc.
The edge portion 21 a of the diaphragm 21 is fixed to the edge portion of the frame 26. The diaphragm 21 and its edge portion 21a are coated with a resin having fire resistance and heat resistance. The driving portion of the speaker 6 will be described. For a cylindrical bobbin 27 that is concentrically fixed to the lower end of the diaphragm 21 and has a metallic voice coil 24 wound around the side periphery thereof and impregnated with heat-resistant resin. Then, the pole piece 28 integrally fixed to the back plate 29 is loosely fitted. A permanent magnet 31 is fixed between the top plate 30 and the back plate 29 fixed to the bottom of the frame 26 at a predetermined interval concentrically with the pole piece 28. Further, a spider 23 made of aramid fiber, carbon fiber, glass fiber or the like is stretched between the inner surface of the frame 26 and the bobbin 27.

The speaker 6 is constructed as described above, and the vibration system of the speaker 6 is excellent in heat resistance and water resistance. That is, since the exhaust gas of the engine becomes a high temperature of about 600 ° C., it is necessary to prevent the performance deterioration of the speaker 6 due to heat transfer. In addition,
The speaker 5 is thermally insulated from the casing 5 by the mounting structure of the speaker 6 as shown in FIG. That is, the frame 26 of the speaker 6 has the opening 16 a formed in the partition wall 16 that divides the air chamber 7 and the closed space 8 in the casing 5.
On the other hand, they are attached by bolts 18 and nuts 19, but between the frame 26 and the partition wall 16, between the bolt 18 and the frame 26, and between the partition wall 16 and the nut 19, there are heat insulating materials 17, 17 ', 17 ", respectively. Is fixed through.

Outside the exhaust pipe 2, in the vicinity thereof, there is a muffling deviation detector or microphone 13 which is the muffling deviation detecting means of the present invention.
Is arranged so as to be located at the center of the exhaust pipe 2 (the center of the sound source), and the detection output e is supplied to the muffling signal generator 14 described later. As shown in FIG. 29A, the muffling deviation detection microphone 13 as the sound receiving unit is
It is arranged in an opaque cylindrical closed casing 34 with a windshield 34a having a conical shape, and behind this closed casing 34 is a sound wave inlet 32 that is a second sound path, and The muffler deviation detection microphone is provided with the elastic casing 33 provided with the communication hole 48 and the closed casing 3
4 It is fixed near the tip inside. That is, the path lengths of the sound waves introduced from the front surface and the back surface of the muffling deviation detector 13 are made different so that the sound waves introduced from the front surface have a positive phase. The sound waves introduced from the back surface have opposite phases so that the sound waves from the front surface are received with high sensitivity, so-called directivity.

A cover 49 is attached to the sound wave inlet 32. The cover 49 and the windshield 3 are attached.
The material 4a is formed by molding and processing a thin material having heat resistance and water resistance, such as a plate or cloth made of glass fiber or carbon fiber, and Teflon, and having good sound permeability.

Next, referring to FIG. 5, the muffling signal generator 14
Will be described in detail. The analog output REF of the vibration detector 38 for detecting the vibration of the engine is the amplifier 39, A /
It is supplied to an adaptive filter (hereinafter abbreviated as ADF) 41 and a delay filter 42 via a D converter 40. Further, the detection output e of the muffling deviation detection microphone main body 35 built in the muffling deviation detector 13 is the amplifier 46.
It is supplied to the coefficient calculator 43 via the A / D converter 47. The ADF 41 has N multipliers, that is, N taps, the coefficients of which are updated by the output of the coefficient calculator 43. Further, the delay filter 42 has an acoustic transfer characteristic corresponding to a path from the speaker 6, 6 → the air chamber 7 → the acoustic port 9 → the silence deviation detector 13 in FIG. That is, the coefficient of the delay filter 42 is determined in consideration of this time delay, which is measured or identified in advance and provided. Further, the coefficient calculator 43 is an adaptive algorithm for sequentially calculating the optimum coefficient given to the ADF 41.

The analog noise signal REF detected and amplified by the vibration detector 38 is digitally converted by the A / D converter 40 to obtain the noise signal x. The noise signal x is input to the ADF 41, and at the position of the muffling deviation detector 13, a muffling signal y having the same amplitude as the exhaust noise (noise) and having the opposite phase is calculated. Obtained silence signal y
Is converted to analog by the D / A converter 44, amplified by the amplifier 45, and supplied to the speakers 6, 6. The silence signal generator 14 has a configuration using the above-described known ANC (active noise control) technology.

The silencer 1 according to the first embodiment of the present invention is configured as described above, and its operation will be described below.

The muffling signal generator 14 generates a muffling signal y by the detection output REF of the vibration detector 38 for detecting the vibration of the engine and the detection output e of the muffling deviation detector 13, which is supplied to the speakers 6, 6. To be done. Speaker 6,
As described above, 6 drives the resonance system formed by the air chamber 7 and the acoustic port 9 to generate a silencing sound wave. This muffling sound wave is exhausted by the muffling signal generator 14 (noise).
Since the exhaust sound is canceled by interference with the sound deadening sound wave, the deviation is detected by the sound deadening deviation detector 13, and By supplying the detection output e to the muffling signal generation device 14, the muffling signal y is controlled so that the noise becomes zero at the position of the muffling deviation detector 13. Also,
High-frequency noise that cannot be silenced due to the cancellation of the sound-deadening sound waves is sufficiently reduced by the above-mentioned sub-muffler (not shown) arranged on the upstream side of the exhaust pipe 2, so that the open end 2a of the exhaust pipe 2 is consequently reduced. The noise at is almost zero.

Further, the mute deviation detector microphone 35 is the windshield 3
The elastic support member 33 is provided in the closed casing 34 provided with 4a.
Since it is supported by, it is possible to detect the muffling deviation with a good S / N ratio without being affected by the air flow noise and vibration due to the exhaust gas. Further, since it is not affected by wind, rain, dust or sunlight, its performance can be maintained for a long period of time.

As described above, the muffler 1 of this embodiment
According to, since the path of the exhaust gas can be straightened,
Exhaust resistance is reduced, output loss of the engine is also reduced, and fuel consumption can be improved. Further, since the resonance system using the air chamber 7 and the acoustic port 9 is formed, it is possible to generate the silencing sound wave with energy saving and extremely efficiently as compared with the configuration without using the resonance system, which has been conventionally considered difficult.
Noise of 0 Hz or less can also be efficiently saved with energy saving.

Further, since the exhaust gas does not come into direct contact with the speaker 6, the influence of heat, dust, humidity, static pressure, pulsating pressure fluctuation, etc. can be eliminated, and stable performance is maintained for a long period of time. be able to. Further, the size of the entire device can be made approximately the same as that of the conventional main silencer, and there is no influence on the external dimensions such as the total length and height of the vehicle.

FIGS. 6 and 7 show a silencer according to a second embodiment of the present invention, the whole of which is designated by 51, and the portions corresponding to those of the first embodiment are designated by the same reference numerals. Detailed description thereof will be omitted.

The interior of the main silencer 52 in this embodiment is
Similar to the first embodiment, the partition wall 56 forms the air chamber 54 and the closed space 55, and the speakers 6 and 6 are arranged facing the air chamber 54 . Similarly, outside the open end 2a of the exhaust pipe 2, one end communicates with the air chamber 54 by a length L ₁
The first acoustic port 57 is formed concentrically with the exhaust pipe 2,
These exhaust pipes 2 so as to be positioned between the first acoustic port 57, again with concentric with the exhaust pipe 2, one end of the closed space 5
A second acoustic port 58 having a length L _{2 and} communicating with 5 is formed. The other ends of the first and second acoustic ports 57 and 58 are on the same line as the end face of the open end 2a of the exhaust pipe 2 and are open to the outside, and the net-shaped filters are provided at these ends. 59 and 60 are attached to prevent foreign matter from entering from the outside. Furthermore, the silence deviation detector 13
However, similarly to the first embodiment, it is located in the central portion near the outside of the exhaust pipe 2, and its detection output e is supplied to the muffling signal generator 14.

That is, in this embodiment, the acoustic first resonance system formed by the stiffness of the air determined by the volume of the air chamber 54 and the predetermined air mass determined by the volume in the first acoustic port 57 having the length L ₁ . And an acoustic second resonance system formed by a predetermined air mass determined by the stiffness of the air in the closed space 55 and the volume in the second acoustic port 58 having the length L ₂ , forming two resonance systems, The resonance frequency f of the first resonance system
₁ and the resonance frequency f ₂ of the second resonance system are separated from each other by a frequency (f
₁ > f ₂ ).

The silencer 51 according to the second embodiment of the present invention is constructed as described above, and its operation will be described below.

The muffling signal generator 14 generates a muffling signal y by the detection output REF of the vibration detector 38 for detecting the vibration of the engine and the detection output e of the muffling deviation detector 13, which is supplied to the speakers 6, 6. To be done. Speaker 6,
6 drives the first resonance system formed by the air mass of the air chamber 54 and the air volume of the first acoustic port 57, and closes the closed space 55.
And drives the second resonance system formed by the second acoustic port 58. Due to the stiffness of the air chamber 54 and the closed space 55 , and the air mass of the first and second acoustic ports 57 and 58, _two different frequencies f ₁ and f ₂ (f ₁ > f) are obtained.
₂ ), so that the sound-deadening sound wave can be efficiently generated over a wide frequency band as shown in FIG. 28, so that the noise from the exhaust pipe 2 can be more efficiently saved. it can.

FIGS. 8 and 9 show a silencer according to a third embodiment of the present invention, the whole of which is shown at 62, and the portions corresponding to those of the second embodiment are designated by the same reference numerals. Detailed description thereof will be omitted.

Inside the casing 64 of the main silencer 63,
Air chambers 65 1 , 65 are formed in a ring shape by the partition wall 66 communicating with each other, and speakers 6, 6 are arranged with the air chambers 65 1 , 65 in front. In this embodiment, the speaker 6,
An acoustic resonance tube 70 is formed by bending inside the casing 64 in the rear space 67 1 , 67 of 6. Further, similarly to the second embodiment, the first and second acoustic ports 68 and 69 are arranged concentrically with the open end 2a of the exhaust pipe 2, one end of which is respectively the air chambers 65 and 65 and the acoustic ports. Resonance tube 70, 70
, And the other end is open to the outside. The acoustic resonance tubes 70, 70 are formed such that their cross-sectional areas are substantially uniform from the rear of the speakers 6, 6 to the opening end of the second acoustic port 69, and their resonance frequency is the sound path length, that is, It depends on the total length of the acoustic resonance tubes 70, 70 and the second acoustic port 69. That is, the acoustic resonance tube 70,
70 has a long shape because air column resonance is used to resonate the silencing sound wave with the main frequency component of the noise, but is formed by bending so that the external shape of the device is compact.

That is, the stiffness of the air chamber 65 and the first
A first resonance system formed by the air mass of the acoustic port 68;
A second resonance system is formed by the acoustic path lengths of the acoustic resonance tubes 67 1 , 67 and the second acoustic port 69, and the respective resonance frequencies f
By setting ₁ and f ₂ so as to be different from each other, noise from the exhaust pipe 2 can be effectively silenced over a wide frequency band as in the second embodiment. However, in the present embodiment,
It differs from the second embodiment in that the resonance frequency f ₂ is obtained by a resonance tube utilizing air column resonance.

FIG. 10 and FIG. 11 show a silencer according to a fourth embodiment of the present invention, the whole of which is shown at 71, and the portions corresponding to those of the first embodiment are designated by the same reference numerals. Detailed description thereof will be omitted.

In the casing 73 of the main silencer 72, partition walls 74 and 75 and a partition plate 83 (see FIG. 11) form first and second air chambers 77 and 78 having different volumes. Speakers 6 and 6 are arranged with the second air chambers 77 and 78 in front. The space behind the speakers 6, 6 is formed as first and second closed spaces 79 , 80 , but these are also independent of each other. Further, a partition wall 76 is provided behind the first closed space 79 (upward in FIG. 10).
Thereby forming an auxiliary space 81 , which communicates with the second closed space 80 . Furthermore, the first and second air chambers 7
The inner space of the acoustic port 82, one end of which communicates with 7 , 78 , is divided into two by a partition plate 83.

That is, by constructing two resonance systems having different resonance frequencies by the acoustic port 82 divided into two and the first and second air chambers 77 , 78 having different volumes, the exhaust pipe 2 Muting sound waves having two resonance frequencies are generated on both sides of the opening end 2a of the above, and the noise can be effectively suppressed as in the second and third embodiments.

FIGS. 12 and 13 show a silencer according to a fifth embodiment of the present invention, the whole of which is shown at 86, and the portions corresponding to those of the first embodiment are designated by the same reference numerals. Detailed description thereof will be omitted.

The inner wall of the casing 88 of the main silencer 87 is
As shown in the figure, it is fixed in contact with the outer wall of the exhaust pipe 2, and the inside thereof is partitioned by a partition wall 91 into an air chamber 89 and a closed space 9.
0 is formed, and the speaker 6 is arranged with the air chamber 89 in the front. Also, unlike the above-described embodiments, the air chamber
The acoustic port 92, one end of which communicates with 89 , is arranged not concentrically with the open end 2 a of the exhaust pipe 2 but in the vicinity thereof.
A filter 93 on the net is provided at the open end of the acoustic port 92.

Also in this embodiment, the sound absorbing sound wave is efficiently generated from the acoustic port 92 by the resonance system formed by the stiffness of the air chamber 89 and the air mass of the acoustic port 92. Further, although the sound source diameter is larger than that in the case where the acoustic port 92 is arranged concentrically with the exhaust pipe 2, the same silencing effect as in the above-described first embodiment can be obtained.

FIGS. 14 to 16 show a silencer according to a sixth embodiment of the present invention, the whole of which is designated by 96, and the portions corresponding to those of the first embodiment are designated by the same reference numerals. Detailed description thereof will be omitted.

The casing 98 of the main silencer 97 of this embodiment.
Unlike the above-described embodiments, the inside is divided into an air chamber 100 and a closed space by a partition wall 99 that is bent at a right angle as shown in FIG.
101 is formed, and the speakers 6, 6 arranged facing the air chamber 100 are directed downward toward the gravity, that is, generate a sound deadening sound wave on the bottom surface of the casing 98.

According to this embodiment, the same operation as that of the first embodiment can be obtained, and even if a large amount of water is mixed from the acoustic port 9, it can directly contact the diaphragm 21 of the speaker 6. Therefore, the operation of the speaker 6 can always be kept stable.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiments, the speaker 6 as the sound wave generating means has been described as a dynamic speaker, but instead of this, a piezoelectric speaker, a combination of a piston and a linear motor, or a combination of a piston and a crank. It may be a thing.

FIG. 17 shows a front view of the main silencer. The casing 103 has a cylindrical shape, and a plurality of speakers 6 (four in the figure) serving as sound wave generating means face one air chamber. This is an example in which a sound-deadening sound wave having a higher sound pressure is generated by arranging them. In this way, when using multiple speakers, the closed space behind may be shared,
When each speaker is independently provided by partitioning with a partition plate or the like, distortion and interference are improved, and a more excellent silencing effect can be obtained.

FIG. 18 shows a modification of the above-mentioned second embodiment. In the figure, the parts corresponding to those in FIG. 6 are designated by the same reference numerals, and the reference numerals are denoted by ('). That is, in the second embodiment, the first acoustic port 5
7 is formed on the outer peripheral side of the second acoustic port 58, this modification is an example in which the second acoustic port 58 ′ is formed on the outer peripheral side of the first acoustic port 57 ′. Also in this modification, the second
Of course, it is possible to obtain the same effect as that of the embodiment, and the same modification can be made to the third embodiment based on the same technical idea.

FIG. 19 shows a modification of FIG. 18,
18, the parts corresponding to those in FIG. 18 are denoted by the same reference numerals, and the reference numerals are denoted by (). That is, in this modification, a plurality of speakers 6 ″ facing the air chamber 54 ″ (main modification) are used. (4 in the example),
It is possible to generate a silenced sound wave having a higher sound pressure. In addition,
If the air chamber 54 " is the first air chamber and the closed space 55" is the second air chamber, the second acoustic port 58 "is eliminated and the second air chamber is removed.
It is naturally possible to make 55 ″ a closed space, or to eliminate the first acoustic port 57 ″ and make the first air chamber 54 ″ a closed space.

FIG. 20 shows a modification of the above-described third embodiment. In the figure, the parts corresponding to those in FIG. 8 are designated by the same reference numerals, and the reference numerals are denoted by ('). That is, in this modified example, the front spaces 104 1 , 104 2 of the speakers 6 ′, 6 ′ are formed as the acoustic resonance tubes 105, 105, and a resonance frequency different from the resonance frequency of the acoustic resonance tube 67 ′ is obtained. Is. Also in this modification, the same effect as in the third embodiment is obtained, and since the sound path through which the silencing sound waves pass is formed by being bent, a large sound pressure can be efficiently generated with a compact shape. .

Further, in the above-mentioned embodiments, the muffling deviation detector 13 arranged outside the exhaust pipe 2 is described as being located at the center of the sound source, that is, at the center of the exhaust pipe 2, but the present invention is not limited to this. . That is, the position of the muffling deviation detector 13 is
It suffices that the opening end 2a of the exhaust pipe 2 is separated from the open end 2a by at least 1 times the diameter of the sound source. For example, as shown in FIG. Since it can be increased and the influence of the air flow is also small, its stability and sound deadening performance can be improved.

Further, in the above-described fourth embodiment, the volumes of the first and second air chambers 77 and 78 are changed to form two different resonance systems, but instead of this, the partition plate 8 is used.
Even if the position of 3 is changed and the internal volume of the acoustic port 82 is changed, it is clear that the same effect can be obtained. In the embodiment, each of the two air chambers and the internal space of the acoustic port is formed, but a plurality of internal spaces may be formed.

Further, as shown in FIG. 21, an annular air chamber
By mounting the shielding member 108 in the vicinity of the acoustic port 9 in 107 , even if a water stream having a pressure enters from the opening end of the acoustic port 9, the speaker 6 is not directly contacted with the speaker 6, 6 and is protected. It is possible to stabilize the operation at all times. The shape of the shielding member 108 may be, for example, a ring shape larger than the inner diameter of the acoustic port 9, and may be fixed to the exhaust pipe 2.

The water drain hole is necessary at the time of rain or car wash, and this hole can be formed at any bottom wall or side wall bottom of the air chamber. However, as shown in FIG. 2 (first embodiment), the water drain hole 10 is formed.
Is formed on the bottom of the side wall on the side of the acoustic port 9, leakage sound from the water drain hole is also detected by the silencer deviation detector 13 with high sensitivity,
Since the mute control is performed on the synthetic sound including the leaked sound, the muffling performance hardly deteriorates. Although the water draining hole and the evaporation hole are described and illustrated only in the first embodiment, it is assumed that they are formed in other embodiments (however, the forming positions are different in each embodiment).

22 and 23 show the acoustic port 110.
The bottom surface of the air chamber 111 is the bottom surface of the air chamber 111 in the casing 112 (FIG. 22 shows a side sectional view of the casing 112 for the sake of explanation, but the air chamber 111 is annular as in the first embodiment).
The acoustic port 110 also serves as a drainage hole by making it the same as that of the air chamber 11 without affecting the muffling performance.
1 water can be discharged. In addition, acoustic port 1
Even if the bottom surface of 10 is lower than the air chamber 111 , the same effect can be obtained. Also, based on the same technical idea, by making the top surface of the acoustic port the same as the top surface of the air chamber or making the acoustic port side higher, the acoustic port also serves as a vaporization hole for water vapor, which has no effect on the silencing performance. Without, the water vapor in the air chamber can be discharged.

Further, as shown in FIG. 24, the acoustic port 114 is formed into a vertical elliptical shape such that the top and bottom of the acoustic port 114 coincide with the top and bottom of the air chamber, respectively. Needless to say, both functions can be performed at the same time with respect to vaporization of water vapor and
Since the sound source is a vertically long ellipse, the horizontal spread of the sound deadening sound waves is improved, and the most problematic noise propagating in the horizontal direction can be more effectively muted. Further, in this case, as shown by the alternate long and short dash line in the figure, the muffling deviation detector 13 can be further enhanced by arranging it at a position where it can detect a sound wave spreading in the horizontal direction with high sensitivity.

Further, as shown in FIGS. 25 and 26,
By attaching the opaque hood 116 to the acoustic tube 117, the inside of the air chamber inside the casing 118 can be made dark, and since raindrops can be prevented from mixing in, the operation of the speaker can be stabilized for a long period of time. Furthermore, the sunlight can be shut out to protect the speaker.

Moisture in the air chamber is efficiently evaporated by heat conduction from the exhaust pipe, but a material having good heat conduction may be used for a member forming the air chamber, that is, a casing or a partition wall, or as shown in FIG. , Heating wire 12 for evaporation of water
1,121 to be provided on the bottom of the air chamber 120, 120 can be more efficiently evaporated.

Further, by installing a sound absorbing material on the inside of the air chamber or on the inner wall of the acoustic port, or by tilting one of the facing parallel surfaces of the air chamber, unnecessary standing waves and noise can be suppressed. Since the number of taps of the delay filter can be reduced (the number of taps is determined by the decay time of the sound) and the calculation time can be shortened, the silencing performance of high frequency components can be extended and the cost of the silencing signal generator can be reduced.

The muffling deviation detector 13 is the same as that shown in FIG.
The configuration is not limited to this, and may be configured as in FIGS. 29B to 29D. That is, FIG. 29B has a plurality (six locations in the figure).
29C is an example in which the sound wave introduction port of FIG. This is an example of improving the S / N ratio. Further, FIG. 29D is similar to FIG. 29C, and the windshield 1 having a streamline shape is formed at the front and rear ends of the closed casing 126.
26a and 126b are provided to improve the S / N ratio, and the sound absorbing material 127 is provided inside, so that the resonance sound inside the closed casing 126 is reduced, and the silencing deviation can be detected more reliably. Here is an example.

Further, although the acoustic ports described in the above embodiments are both straight pipes, if the opening end is R-shaped, the air flow noise when the air in the acoustic port vibrates can be reduced, It is possible to obtain a better muffling effect. Further, as shown in FIG. 30, an acoustic horn 130 having a curved shape such as straight, exponential or hyperbolic is provided at the opening end of the acoustic port 129, and is provided inside the acoustic horn 130 or near the opening end of the acoustic horn 130. By arranging the muffling deviation detector 13, it is possible to greatly reduce the influence of surrounding acoustic characteristics and disturbance, and it is possible to more reliably and stably perform the muffling operation. further,
It is obvious that the same effect can be obtained even if the cross-sectional shape of the acoustic port is not limited to a circle or an ellipse, but a quadrangle or another polygon.

Further, as in the above second and third embodiments,
In the example in which the two acoustic ports are arranged concentrically with the exhaust pipe, the sound source diameter is large, but as shown in FIG. 31, the inner second acoustic port 133 is slightly shorter than the exhaust pipe 2, and the outer second acoustic port 133 is By narrowing the opening end of the 1-acoustic port 132 inward, the diameter of the sound source can be made small, the directional characteristics and the high-range sound deadening limit are improved, and more excellent sound deadening performance can be exhibited.

Furthermore, in each of the above embodiments, the muffler has been described as a vehicle muffler, but the present invention is not limited to this, and exhaust in a power generation system such as a cogeneration system that recovers engine exhaust heat and simultaneously supplies electric power and heat. The muffler can also be applied to the present invention. In each of the above embodiments, the length of the acoustic port is L, L ₁ or L ₂ , but it is clear that the resonance frequency of the resonance system can be changed only by changing the length. Further, the resonance system may not be formed.

[0064]

As described above, according to the silencer of the present invention, the output loss of the engine can be significantly reduced while the size of the entire device is almost the same as the conventional one, and it has been difficult to achieve the conventional technique. Noise in the low frequency band can also be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a silencer according to a first embodiment of the present invention.

FIG. 2 is a front view of the same.

FIG. 3 is an enlarged cross-sectional view of a speaker as a sound wave generating unit of the device.

FIG. 4 is a partially cutaway sectional view showing a mounting structure of the sound wave generating means.

FIG. 5 is a block diagram of a silence signal generation device of the same device.

FIG. 6 is a sectional view showing a silencer according to a second embodiment of the present invention.

FIG. 7 is a front view of the same.

FIG. 8 is a sectional view showing a silencer according to a third embodiment of the present invention.

FIG. 9 is a front view of the same.

FIG. 10 is a sectional view showing a silencer according to a fourth embodiment of the present invention.

FIG. 11 is a front view of the same.

FIG. 12 is a sectional view showing a silencer according to a fifth embodiment of the present invention.

FIG. 13 is a front view of the same.

FIG. 14 is a sectional view showing a silencer according to a sixth embodiment of the present invention.

FIG. 15 is a front view of the same.

FIG. 16 is a side view of the same.

FIG. 17 is a diagram showing a modification of the shape of the casing of the main silencer in the silencer of the present invention.

FIG. 18 is a diagram showing a modification of FIG. 6.

FIG. 19 is a diagram showing a modification of FIG. 18.

20 is a diagram showing a modification of FIG. 8. FIG.

FIG. 21 is a cross-sectional view showing a mounting example of a shielding member which is a modified example of the above embodiment.

FIG. 22 is a side sectional view showing a modified example of the water drain hole in the first embodiment of the present invention.

FIG. 23 is a front view of the same.

FIG. 24 is a front view showing a modified example of the water drainage hole and the evaporation hole in the first embodiment of the present invention.

FIG. 25 is a side view showing a mounting example of a hood which is a modified example of the above embodiment.

FIG. 26 is a front view of the same.

FIG. 27 is a cross-sectional view showing a mounting example of a heating wire which is a modified example of the above embodiment.

FIG. 28 is a diagram for explaining the operation of the second to fourth embodiments of the present invention.

FIG. 29A is a cross-sectional view of a muffling deviation detector as a muffling deviation detecting means according to the present invention, and FIGS. 29A to 29D are views showing modifications of A, respectively.

FIG. 30 is a sectional view of an acoustic horn showing a modification of the embodiment of the present invention.

FIG. 31 is a sectional view showing a modification of the shape of the acoustic port in the second to fourth embodiments of the present invention.

[Explanation of symbols]

1 silencer 2 exhaust pipe 5 casing 6 speaker 7 air chamber 8 closed space 9 acoustic port 10 drainage hole 12 evaporation hole 13 silencer deviation detector 14 silencer signal generator 51 silencer 53 casing 54 air chamber 55 closed space 57 1st Acoustic port 58 Second acoustic port 62 Silencer 64 Casing 65 Air chamber 70 Acoustic resonance tube 68 First acoustic port 69 Second acoustic port 71 Silencer 73 Casing 77 First air chamber 78 Second air chamber 79 First closed space 80 Second closed space 83 Partition plate 86 Silencer 88 Casing 89 Air chamber 90 Closed space 92 Acoustic port 96 Silencer 98 Casing 100 Air chamber 101 Closed space 105 Acoustic resonance tube 108 Shielding member 116 Hood 121 Electric heating wire 130 Acoustic horn

Claims (17)

[Claims] 1. A sound deadening deviation detecting means is arranged near the outside of a straight exhaust pipe, at least one sound wave generating means is installed in the vicinity of the exhaust pipe, and a rear side of the sound wave generating means is hermetically sealed. A closed casing having a closed space is provided, an air chamber is provided in front of the sound wave generating means, and an acoustic port is installed so as to concentrically surround the exhaust pipe, one end of which communicates with the air chamber and the other end A muffling device that communicates with the outside. 2. The sound deadening device according to claim 1, wherein the silencer resonates at a main frequency of noise due to the stiffness of the air chamber and the mass of air in the acoustic tube. 3. A sound deadening deviation detecting means is arranged in the vicinity of a linear exhaust pipe, at least one sound wave generating means is installed in the vicinity of the exhaust pipe, and a rear side of the sound wave generating means is hermetically sealed. A closed casing having a closed space is formed, an air chamber is provided in front of the sound wave generating means, and first and second acoustic ports are installed concentrically with the exhaust pipe,
One end of one acoustic port communicates with the air chamber, one end of the other acoustic port communicates with the closed space, and the other ends thereof communicate with the outside, the stiffness of the air chamber and the one acoustic port. A silencer, wherein a first resonance system is formed by the internal air mass, and a second resonance system is formed by the stiffness of the closed space and the air mass of the other acoustic port. 4. The silencer according to claim 1, wherein a plurality of sound wave generators are arranged facing the air chamber. 5. A sound deadening deviation detecting means is arranged near the outside of the straight exhaust pipe, at least one sound wave generating means is installed near the exhaust pipe, and an air chamber is provided in front of the sound wave generating means. First and second acoustic ports are installed concentrically with the exhaust pipe, one end of one acoustic port communicates with the air chamber, and one end of the other acoustic port communicates with the back space of the sound wave generating means. The other end of each is in communication with the outside,
A first resonance system is formed by the stiffness of the air chamber and the air mass in the one acoustic port, and a predetermined pipeline from the back space to the opening facing the outside of the other acoustic port is formed. A silencer characterized by being formed by bending and forming a second resonance system determined by the total length of the conduit. 6. A muffling deviation detecting means is arranged near the outside of the exhaust pipe in a straight line, and at least one sound wave generating means is installed in the vicinity of the exhaust pipe, and first and second concentric with the exhaust pipe. An acoustic port is installed, one end of one acoustic port communicates with the back space of the sound wave generating means, one end of the other acoustic port communicates with the front space of the sound wave generating means, and the other end of each of the sound ports is external. The two predetermined pipelines that are in communication with each other and are bent from the two spaces of the back space and the front space to the outwardly facing openings of the one acoustic port and the other acoustic port are bent. A silencer characterized by being formed independently of each other and forming two resonance systems determined by the total length of the pipe. 7. The sound deadening device according to claim 3, wherein the outermost acoustic tube of the first and second acoustic tubes is narrowed inward to have a small diameter. 8. A sound deadening deviation detecting means is arranged in the vicinity of a linear exhaust pipe, at least one sound wave generating means is installed in the vicinity of the exhaust pipe, and a rear side of the sound wave generating means is hermetically sealed. A closed casing having a closed space is formed, an air chamber is provided in front of the sound wave generating means, and an acoustic port is installed in the vicinity of the exhaust pipe, one end of which communicates with the air chamber and the other end of which is outward. A silencer characterized by communicating with. 9. An air chamber having a different volume faces the plurality of sound wave generating means, the internal space of the acoustic port is partitioned into a plurality of spaces, and each space inside the acoustic port is divided into a plurality of spaces.
The silencer according to claim 4, which is in communication with any one of the air chambers. 10. The silencer according to claim 1, wherein a shielding member having an outer dimension larger than an inner dimension of the acoustic port is arranged inside the air chamber in the vicinity of the acoustic port. 11. The silencer according to claim 1, wherein the sound wave generator is arranged downward with respect to gravity. 12. The silencer according to claim 1, wherein a bottom surface inside the acoustic port is formed so as to match or be lower than a bottom surface inside the air chamber. 13. The silencer according to claim 1 or 2, wherein a top surface inside the acoustic port is formed so as to match or be higher than a top surface inside the air chamber. 14. The silencer according to claim 1, wherein an opaque hood is attached to an end of the opening of the acoustic port. 15. The silencer according to claim 1, wherein a heating wire is arranged on the bottom surface of the air chamber. 16. The silencing deviation detecting means is a conical shape,
Alternatively, the sound-receiving part is vibration-isolated and supported near the tip of an opaque closed capsule having a streamlined shape, a windshield is provided on the front surface, and one or more openings are provided on the side surface or the rear portion. The silencer according to any one of claims 1 to 15, wherein the part is made of an opaque material having a low density. 17. The silencer according to claim 1, wherein a member having a horn shape is attached to the opening of the acoustic port.