JPH0614422U - Active silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to an active silencer in which the noise of exhaust gas is positively silenced by a secondary sound source. The purpose is to reduce. A muffler body 41 is partitioned by a partition wall 43 to form a muffler chamber 45, and an exhaust pipe 49 that circulates exhaust gas is inserted into the muffler chamber 45 to form an opening 53 formed in the partition wall 43. In the active silencer in which the secondary sound source 55 is arranged, the upstream side end 65 of the secondary sound source 55 in the portion of the exhaust pipe 49 located in the silencing chamber 45.
The through hole 69 is formed only in a portion located on the upstream side or the downstream side of the downstream end 67.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an active silencer in which exhaust noise is positively silenced by a secondary sound source.

[0002]

[Prior art]

 Conventionally, as an active silencer that positively silences the noise of exhaust gas by a secondary sound source, for example, the one disclosed in Japanese Patent Publication No. 58-501292 is known.

FIGS. 7 and 8 show an active silencer of this type. In the drawings, reference numeral 11 indicates a silencer body having a rectangular cross section. The muffler body 11 is divided into three parts by a partition wall 13 arranged at a predetermined interval, a muffling room 15 is formed in the center, and speaker rooms 17 are formed on both sides of the muffling room 15.

An exhaust pipe 19 that circulates the exhaust gas G is inserted into the muffler chamber 15. The exhaust pipe 19 has a large number of small exhaust pipes in a portion located inside the muffler chamber 15. The hole 21 is formed.

An opening 23 is formed in the pair of partition walls 13 at a position facing each other around the exhaust pipe 19, and a speaker 25 as a secondary sound source is arranged in the opening 23. A protective plate 27 for protecting the speaker 25 is arranged in the opening 23 of the partition wall 13, and a large number of small holes 29 are formed in the protective plate 27.

A sound absorbing material 31 made of, for example, glass wool is housed in the muffling room 15 and the speaker room 17. In addition, a microphone 33 is arranged in the muffling chamber 15.

In such an active silencer, the noise of the exhaust gas G is detected by the microphone 33, and a erasing sound having a phase opposite to the detected noise is radiated from the speaker 25, so that the so-called active muffling is performed. Is done.

[0008]

[Problems to be solved by the device]

 However, in such a conventional active silencer, since the small hole 21 is formed over the entire surface of the exhaust pipe 19 located in the muffler chamber 15, the exhaust gas from the small hole 21 located near the speaker 25 is formed. Since the heat of 2 reaches the speaker 25 in a relatively short distance, a large heat load is applied to the speaker 25, and there is a problem that the heat resistant design value of the speaker 25 needs to be increased.

The present invention has been made to solve such a conventional problem, and an object thereof is to provide an active silencer capable of significantly reducing the heat load acting on the secondary sound source as compared with the conventional silencer. To do.

[0010]

[Means for Solving the Problems]

 In the active silencer of the present invention, the silencer body is partitioned by a partition wall to form a muffler chamber, and an exhaust pipe that circulates exhaust gas is inserted into the muffler chamber, and an opening formed in the partition wall In an active silencer with a secondary sound source, only the portion of the exhaust pipe located in the muffler chamber is located upstream of the upstream end of the secondary sound source or downstream of the downstream end. A through hole is formed.

[0011]

[Action]

 In the active silencer of the present invention, the through hole is formed only in the portion of the exhaust pipe located in the silencer chamber, which is located upstream of the upstream end of the secondary sound source or downstream of the downstream end. Therefore, the distance between the through hole located closest to the secondary sound source and the secondary sound source becomes large.

[0012]

【Example】

 Hereinafter, the details of the present invention will be described with reference to the embodiments shown in the drawings. 1 and 2 show a first embodiment of an active silencer of the present invention, in which the reference numeral 41 designates a silencer body having a rectangular cross section.

The muffler body 41 is divided into three by a pair of partition walls 43 arranged at a predetermined interval, a muffling chamber 45 is formed in the center, and speaker chambers 47 are formed on both sides of the muffling chamber 45. ing.

An exhaust pipe 49 that circulates the exhaust gas G is inserted into the muffling chamber 45. An opening 53 is formed in the pair of partition walls 43 at a position facing each other around the exhaust pipe 49. In this embodiment, the center of the opening 53 is located at the downstream end of the silencer body 41. It is located at a distance of 1/3 of the total length of the silencer body 41.

A speaker 55, which is a secondary sound source, such as a round speaker, is arranged in the opening 53. A protective plate 57 for protecting the speaker 55 is arranged in the opening 53 of the partition wall 43, and a large number of small holes 59 are formed in the protective plate 57.

A sound absorbing material 61 made of, for example, glass wool is housed in the muffling room 45 and the speaker room 47. A microphone 63 is arranged in the muffling chamber 45.

In this embodiment, therefore, of the portion of the exhaust pipe 49 located inside the muffler chamber 45, the portion located upstream of the upstream end 65 and downstream of the downstream end 67 of the speaker 55. A small hole 69 is formed only in the.

That is, in this embodiment, the length of the opening 53 formed in the partition wall 43 in the axial direction is L _1, and the distance from the upstream end 65 of the opening 53 toward the upstream side is more than the distance L ₂ . A small hole 69 is formed on the upstream side, and a small hole is formed further downstream from the distance L ₃ from the downstream end 67 of the opening 53 toward the downstream side.

In the above-described active silencer, the noise of the exhaust gas G is detected by the microphone 63, and the erasing sound having a phase opposite to the noise is radiated from the speaker 55, so-called active silencing is performed. .

In the above-described active silencer, however, of the portion of the exhaust pipe 49 located inside the silencer chamber 45, the upstream side of the upstream end 65 of the speaker 55 and the downstream side of the downstream end 67 thereof. Since the small hole 69 is formed only in the portion located at, the distance between the small hole 69 located closest to the speaker 55 and the speaker 55 becomes large, and the heat load applied to the speaker 55 is significantly reduced as compared with the conventional case. be able to.

That is, in the conventional active silencer, since the small hole is formed over the entire surface of the exhaust pipe located in the muffler chamber, the heat of the exhaust gas from the small hole located near the speaker is reduced. Since the speaker reaches the speaker in a relatively short distance, a large heat load is applied to the speaker. However, in the active silencer of this embodiment, the small hole 69 located closest to the speaker 55 and the speaker 55 are Since the distance is increased, the heat load acting on the speaker 55 is significantly reduced as compared with the conventional case, and thus the heat resistant design value of the speaker 55 can be significantly reduced as compared with the conventional case.

FIG. 3 shows a second embodiment of the active silencer of the present invention. In this embodiment, a little downstream from the upstream small hole 69 formed in the exhaust pipe 49, and A heat shield partition 71 is arranged in the muffler chamber 45 at a position slightly upstream of the downstream small hole 69.

The thermal barrier 71 is formed of a member having a high thermal barrier property and not impeding the passage of sound waves, for example, a foam metal, a sintered metal, a perforated plate with coarse mesh, a wire mesh with coarse mesh, or the like. There is.

In this active silencer, almost the same effect as in the first embodiment can be obtained, but in this embodiment, the heat of the exhaust gas from the small holes 69 of the exhaust pipe 49 is shielded. Since only the sound wave that is shielded by the heat partition wall 71 and should be silenced flows to the speaker 55, the heat load acting on the speaker 55 can be further reduced.

FIG. 4 shows a third embodiment of the active silencer of the present invention. In this embodiment, a small hole 69 is formed in a portion of the exhaust pipe 49 located in the silencer chamber 45. A heat shield tube 73 is arranged outside the unprotected portion.

Also in this active silencer, substantially the same effect as that of the first embodiment can be obtained, but in this embodiment, the heat radiation from the exhaust pipe 49 is shielded by the heat shield pipe 71. Therefore, the heat load acting on the speaker 55 can be further reduced.

FIGS. 5 and 6 show a fourth embodiment of the active silencer of the present invention. In this embodiment, the partition wall 43A is formed by saw blade-shaped heat radiation fins 75. In this active silencer as well, almost the same effect as in the first embodiment can be obtained, but in this embodiment, the heat radiation from the exhaust pipe 49 is emitted from the space 77 via the heat radiation fins 75. Since the heat is radiated into the atmosphere, the heat load acting on the speaker 55 can be further reduced.

[0028]

[Effect of device]

 As described above, in the active silencer of the present invention, the portion of the exhaust pipe located inside the silencing chamber is located upstream of the upstream end of the secondary sound source or downstream of the downstream end. Since only the through hole is formed, the distance between the through hole located closest to the secondary sound source and the secondary sound source becomes large, and the heat load acting on the secondary sound source can be significantly reduced compared to the conventional method. There is.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a sectional view showing a second embodiment of the active silencer of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the active silencer of the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of the active silencer of the present invention.

FIG. 6 is a perspective view showing the active silencer of FIG.

FIG. 7 is a sectional view showing an example of a conventional active silencer.

8 is a cross-sectional view of FIG.

[Explanation of symbols]

 41 muffler body 43 partition wall 45 muffler chamber 49 exhaust pipe 53 opening 55 speaker (secondary sound source) 65 upstream end 67 downstream end 69 small hole (through hole)

Claims (1)

[Scope of utility model registration request] 1. A muffler body (41) is partitioned by a partition wall (43) to form a muffler chamber (45), and an exhaust pipe (49) for circulating exhaust gas is inserted into the muffler chamber (45). An opening (53) formed in the partition wall (43)
In the active silencer in which the secondary sound source (55) is arranged, the upstream side end of the secondary sound source (55) in the portion of the exhaust pipe (49) located in the silencer chamber (45). (6
5) An active silencer characterized in that a through hole (69) is formed only in a portion located upstream or downstream of the downstream end (67).