JPH0614426U - Active silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to an active silencer in which noise of exhaust gas is positively silenced by a secondary sound source. The purpose is to reliably balance the static pressure. [Structure] Negative pressure generating means 67 for making negative pressure in the muffling chamber 45
And an outside air introduction path 75 that guides outside air to the front surface of the vibrating surface 73.

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.

FIG. 4 and FIG. 5 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 an active silencer, the speaker 25, which is the secondary sound source, is arranged so as to emit the erasing sound directly into the flow of the exhaust gas G. The static pressure due to the resistance loss of the exhaust gas G due to 19 acts on the front surface of the vibrating surface 35 of the speaker 25, the vibration neutral point of the speaker 25 is displaced, the displacement amount of the vibrating surface 35 is reduced, and the silencing performance is deteriorated. There was a problem of doing.

That is, when the static pressures before and after the vibrating surface 35 of the speaker 25 are balanced, the vibrating surface 35 of the speaker 25 is centered on the design neutral point as shown in FIG. Although it is possible to displace by the allowable maximum amplitude δ, as shown in (b), when the neutral point is deviated from the design neutral point by the static pressure on the front surface of the vibrating surface 35, the allowable displacement amount of the vibrating surface 35 becomes δ. ', And the muffling performance deteriorates.

The present invention has been made to solve such a conventional problem, and provides an active silencer capable of reliably balancing the static pressure before and after the vibrating surface of the secondary sound source with a simple structure. The purpose is to

[0011]

[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 silencer chamber and a secondary sound source chamber, and an exhaust pipe that circulates exhaust gas is inserted into the silencer chamber. A through-hole is formed in a portion located inside the silencing chamber, and the vibrating surface side of the secondary sound source housed in the secondary sound source chamber is arranged in the opening formed in the partition wall. In the container, a negative pressure generating means for making a negative pressure in the muffling chamber, and an outside air introduction path for guiding outside air to the front surface of the vibrating surface are provided.

[0012]

[Action]

 In the active silencer of the present invention, the negative pressure is generated in the silencing chamber by the negative pressure generating means, so that the outside air is guided from the outside air introduction path to the front surface of the vibrating surface and the front surface of the vibrating surface becomes the atmospheric pressure. , The static pressure before and after the vibrating surface is the same.

[0013]

【Example】

 Hereinafter, the details of the present invention will be described with reference to the embodiments shown in the drawings. 1 and 2 show an embodiment of an active silencer of the present invention, in which reference numeral 41 denotes 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 muffler chamber 45, and a large number of small holes 51 are formed in a portion of the exhaust pipe 49 located inside the muffler chamber 45. Has been done.

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 on the downstream side of the silencer body 41. It is located at a distance of 1/3 of the entire length of the silencer body 41 from the end.

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, the tail pipe portion 65 of the exhaust pipe 49 is provided with a flare portion 67, which is a negative pressure generating means for generating a negative pressure in the muffling chamber 45. The flare portion 67 is formed by successively increasing the diameter of the tail pipe portion 65 toward the end.

Further, in this embodiment, a partition plate 69 through which the exhaust pipe 49 is inserted is arranged on the downstream side of the speaker 55, and the muffler chamber 45 is divided into two by this partition plate 69 and the partition wall 43. Between the partition plate 69 and the partition plate 69, an outside air introduction chamber 77 that forms a part of an outside air introduction path 75 that guides outside air is formed on the front surface of the vibration surface 73 of the speaker 55.

In this embodiment, no small hole 51 is formed in the exhaust pipe 49 located in the outside air introduction chamber 77. An outer cylinder 79 is arranged so as to surround the tail pipe portion 65 of the exhaust pipe 49, and a part of the outside air introduction passage 75 formed between the outer cylinder 79 and the tail pipe portion 65 is provided in the outside air introduction chamber 77. It is in communication.

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 emitted from the speaker 55, so-called active silencing is performed. .

In the active silencer described above, however, the tail pipe portion 65 is provided with the flare portion 67 which is a negative pressure generating means for making a negative pressure in the silencer chamber 45 at the end of the tail pipe portion 65, and further, the vibrating surface 73. Since the outside air introduction path 75 that guides outside air is provided on the front surface, the static pressure before and after the vibrating surface 73 of the speaker 55 can be reliably balanced with a simple structure.

That is, in this active silencer, since the inside of the muffling chamber 45 is made to have a negative pressure by the flare portion 67 which is a negative pressure generating means, the outside air is guided from the outside air introduction path 75 to the front surface of the vibrating surface 73. As a result, the front surface of the vibrating surface 73 becomes atmospheric pressure, and the static pressure before and after the vibrating surface 73 becomes the same. As a result, the static pressure before and after the vibrating surface 73 of the speaker 55 can be reliably balanced. As in the conventional case, the vibration neutral point of the speaker 55 does not deviate, and it is possible to reliably prevent the silencing performance from degrading due to the deviation of the vibration neutral point.

Further, in the above-described active silencer, the outside air is introduced into the front surface of the vibrating surface 73 of the speaker 55 by the outside air introduction path 75, so that the speaker 55 can be effectively cooled.

FIG. 3 shows another embodiment of the active silencer of the present invention. In this embodiment, a negative pressure is applied to the inside of the silencer chamber 45 at a position facing the speaker 55 in the exhaust pipe 49. A throat blade 81, which is a negative pressure generating means, is arranged.

That is, by arranging the throat blade 81 in the exhaust pipe 49 in this manner, the pressure in the vicinity of the throat blade 81 is made negative by Bernoulli's theorem, and thus the pressure in the muffling chamber 45 is made negative. To be done.

Further, in this embodiment, one end of the outside air introduction pipe 83 forming an outside air introduction path for guiding outside air is provided on the end plate 41 A on the downstream side of the silencer body 41 on the front surface of the vibrating surface 73 of the speaker 55. It is open.

The other end of the outside air introducing pipe 83 is hermetically sealed, and a large number of small holes 85 are opened on the speaker 55 side of the outside air introducing pipe 83. In the active silencer of this embodiment, since the throat blade 81, which is a negative pressure generating means, creates a negative pressure in the muffler chamber 45, the outside air is guided from the outside air introduction pipe 83 to the front surface of the vibrating surface 73. The front surface of the vibrating surface 73 becomes atmospheric pressure, and the static pressure before and after the vibrating surface 73 becomes the same.

Therefore, also in the above-described embodiment, it is possible to obtain substantially the same effect as that of the embodiment shown in FIG.

[0031]

[Effect of device]

 As described above, the active silencer of the present invention is provided with the negative pressure generating means for making a negative pressure in the silencing chamber and the outside air introduction path for guiding the outside air to the front surface of the vibrating surface, so that the structure is simple. This has the advantage that the static pressure before and after the vibrating surface of the secondary sound source can be reliably balanced.

[Brief description of drawings]

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

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

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

FIG. 4 is a sectional view showing an example of a conventional active silencer.

5 is a cross-sectional view of FIG.

FIG. 6 is an explanatory diagram showing displacement of a vibration surface of the speaker of FIG.

[Explanation of symbols]

 41 silencer body 43 partition wall 45 silencer chamber 47 speaker chamber 49 exhaust pipe 51 small hole 53 opening 55 speaker 67 flare portion 73 vibrating surface 75 outside air introduction path 81 throat blade

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G10K 11/16 H 7406-5H

Claims (1)

[Scope of utility model registration request] 1. A silencer body (41) is partitioned by a partition wall (43) to form a silencer chamber (45) and a secondary sound source chamber (47), and exhaust gas is circulated in the silencer chamber (45). While inserting the exhaust pipe (49), the exhaust pipe (4
9) A through hole (51) is formed in a portion located in the muffling chamber (45), and the secondary sound source chamber (47) is further formed in an opening (53) formed in the partition wall (43). In the active silencer in which the vibration surface (73) side of the secondary sound source (55) housed in is arranged, negative pressure generating means (6) for making the inside of the silencing chamber (45) into a negative pressure.
7, 81) and an outside air introduction path (75, 83) for guiding outside air to the front surface of the vibrating surface (73).