JPH05163925A - Muffling device - Google Patents

Abstract

PURPOSE:To obtain a plurality of muffling frequencies for attaining, sufficient noise reduction effect even when noises are wide in frequency range, simplify a structure, facilitate production, and reduce a manufacturing cost. CONSTITUTION:A resonance muffler chamber 2 formed in a cylindrical vessel is coaxially fitted to an outer periphery of an intake duct 1 serving as an air- flow pipe passage. A portion between the intake duct 1 and the resonance muffler chamber 2 is sealed. A communication port 5 composed of a through- hole 3 and a neck 4 is formed on the intake duct 1 in the resonance muffler chamber 2 at its portion on the left side compared to the center part. A partition plate 6 is arranged on the outer periphery of the intake duct 1 so as to pass the center of the communication port 5, for dividing the muffler chamber 2 into a first chamber 2a and a second chamber 2b. An opening 7 is cut out on an upper portion of the partition plate 6 for communicating the first chamber 2a with the second chamber 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for eliminating noise generated or propagating in a flow pipe.

[0002]

2. Description of the Related Art A conventional resonance type silencer has a structure in which a resonance silencing chamber is provided outside the flow duct, and the flow duct and the resonance silencing chamber are communicated with each other through a communication hole. The muffling frequency due to the resonance action of this muffling device is determined only by the volume of the resonance muffling chamber and the area and length of the communication hole (excluding overtones), so it is sufficient when the frequency range of noise is wide. In some cases, it was not possible to obtain such a reduction effect.

Therefore, as described in Japanese Utility Model Laid-Open No. 63-42817, two resonance chambers (resonance silencing chambers) are provided for a pipe (flow air passage) through which gas flows, and the pipe and each resonance chamber are provided. A muffling device has been considered in which resonance tubes (communication tubes) that communicate with each other are provided, and one of the resonance tubes is also communicated with a resonance chamber with which the other resonance tube communicates. According to this muffling device, it is said that a plurality of muffling frequencies can be obtained by performing a muffling action by various combinations of the resonance chamber and the resonance tube.

[0004]

However, in the silencer disclosed in the above publication, the two resonance chambers, the two resonance tubes, and the communication tube for communicating the middle of one resonance tube with the other resonance chamber. However, since the structure is complicated, the manufacturing is difficult and the cost is increased.

The object of the present invention is to solve the above problems, to obtain a plurality of silencing frequencies, to obtain a sufficient reduction effect even in the case where the frequency range of noise is wide, and to manufacture it because the structure is simple. It is an object of the present invention to provide a novel muffling device that is easy to perform and can reduce costs.

[0006]

In order to achieve the above object, the present invention relates to a silencer in which a resonance silencing chamber is externally fitted to the outer periphery of a flow duct, and a communication hole is provided in the resonance duct inside the resonance silencing chamber. And a partition plate that divides the resonance silencing chamber into a first chamber and a second chamber is provided on the outer periphery of the flow pipe that passes through the communication hole, and the communication plate and the first chamber and the second chamber are provided in the partition plate. It is characterized in that an opening portion is provided for communicating with each other.

Here, the "flow air pipe" is not limited to a specific one as long as it is a pipe through which gas flows, and examples thereof include an intake pipe line and an exhaust pipe line of an internal combustion engine. Further, the “resonance silencing chamber” is not limited to a particular shape or size as long as it has a volume necessary to resonate at a desired silencing frequency, and is, for example, a cylinder that is coaxially extrapolated to the outer circumference of the flow duct. A container-shaped or box-shaped silencing chamber can be mentioned.

Further, the "communication hole" includes not only a simple hole formed by forming a hole in the flow pipe, but also a tubular hole formed by adding a pipe to the simple hole. Examples of the opening shape of the communication hole include a circle, an oval, an ellipse, a triangle, and a quadrangle. The number of communication holes may be one, or two or more may be formed so as to be arranged on the circumference of the flow tube. Further, it is preferable that the volumes of the first and second chambers of the resonance silencing chamber divided by the “partition plate” are different from each other. As the "opening",
An example is one in which a part of the partition plate is cut out in a gap shape or a tunnel shape.

[0009]

In the muffler of the present invention, a partition plate for dividing the resonance muffling chamber into the first chamber and the second chamber is provided, and the partition plate has the communication hole, the first chamber and the second chamber mutually. Since the opening for communication is formed, the combination of the communication hole and the first chamber, the combination of the communication hole and the second chamber, and the combination of the communication hole and the entire resonance silencing chamber exhibit the resonance effect. Be done. Therefore, a plurality of silencing frequencies can be obtained, and a sufficient reduction effect can be obtained even when the frequency range of noise is wide. Further, it is only necessary to add a partition plate with an opening to the conventional example, and the structure is simple, so that the manufacturing is easy and the cost can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a silencer provided in an intake pipe of an internal combustion engine for automobiles will be described below with reference to FIGS. The intake duct 1 as an intake pipe line connecting the air cleaner of the internal combustion engine and the fuel injection device is made of polyethylene resin and has an inner diameter of 66 mm and a thickness of 3 mm.
It is formed in a cylindrical shape having a length of 950 mm and a length of 950 mm. A resonance silencing chamber 2 formed of polyethylene resin in the shape of a cylindrical container having an inner diameter of 139 mm and an inner length of 129 mm is coaxially externally fitted to the outer periphery of the air intake duct 1, and is provided between the air intake duct 1 and the resonance silencing chamber 2. Is sealed.

Intake duct 1 in the resonance silencing chamber 2
40 mm in diameter and 3 mm in length to the left of the center of
One through hole 3 (thickness of the intake duct 1) is formed, and an inner diameter 40 continuous with the through hole 3 is formed on the outer surface of the intake duct 1.
A cylindrical neck 4 having a length of 10 mm and a length of 10 mm is fixed.
A communication hole 5 having a length of 13 mm is formed by the through hole 3 and the neck 4, and the communication hole 5 is formed between the intake duct 1 and the resonance silencing chamber 2.
Through the. The outer circumference of the intake duct 1 passing through the center of the communication hole 5 is made of polyethylene resin and has an outer diameter of 13
A partition plate 6 is provided which is 9 mm in diameter, 72 mm in inner diameter, and has a thickness of 3 mm, and is formed into a perforated disk shape to divide the resonance silencing chamber 2 into a first chamber 2a and a second chamber 2b. An opening 7 having a gap width of 46 mm is formed in the upper portion of the partition plate 6 so that the communication hole 5, the first chamber 2a and the second chamber 2b communicate with each other.

The distance from the inner surface of the left side wall of the resonance silencing chamber 2 to the central portion of the thickness of the partition plate 6 is 45 mm (referred to as the first embodiment) or 25 mm (referred to as the first embodiment). Therefore, the volume ratio of the first chamber 2a and the second chamber 2b is 45:84 in the first embodiment, and is 2 in the first embodiment.
It is 5: 104. Now, assuming that the partition plate 6 is not provided, the resonance frequency of the resonance silencing chamber 2, that is, the silencing frequency f0 is expressed by the following equation 1.

[0013]

## EQU1 ## f0 = (C / 2.pi.). Multidot. (S / (V.Lp)) where C = 331.5 + 0.61t: sound velocity (m /
Sec) S = πD ^2/4: cross-sectional area of the communicating hole 5 D: diameter of the communicating hole 5 V: resonance silencer chamber 2 volume Lp = L1 + 0.8D L1: length of the communication hole 5 t: Temperature (℃)

However, in this embodiment, a partition plate 6 is provided which divides the resonance silencing chamber 2 into a first chamber 2a and a second chamber 2b, and the partition plate 6 has a communication hole 5 and a first chamber 2a. Second chamber 2b
Since the opening 7 is formed for communicating with each other,
The following combinations produce resonance effects according to [Equation 1]. Therefore, a plurality of silencing frequencies can be obtained, and a sufficient reduction effect can be obtained even when the frequency range of noise is wide. (1) Resonance action due to the combination of the communication hole 5 and the first chamber 2a. (2) Resonance action due to the combination of the communication hole 5 and the second chamber 2b. (3) Resonance action due to the combination of the communication hole 5 and the resonance silencing chamber 2 as a whole.

In order to investigate the effect of reducing the intake noise according to this embodiment, a speaker is set at one end of the intake duct 1 and a microphone is set at the other end of the intake duct 1, and the sound picked up by the microphone when white noise is generated from the speaker is detected. FF
The test was conducted by a method of analyzing with a T (fast Fourier transform) analyzer. Figure 3 shows the 500H obtained in the test
It shows the sound pressure level of frequency components equal to or lower than z. The broken line in the figure shows the test result of a simple intake duct without a vent hole and a resonance silencing chamber as a comparative example, the two-dot chain line shows the test result of the conventional example excluding the partition plate from the first embodiment, the solid line Indicates the test result of the first example, and the alternate long and short dash line indicates the test result of the first example.

As is apparent from the figure, in the comparative example, 1
A clear resonance occurs at each resonance frequency centered at 40 Hz, 230 Hz, 340 Hz, and 460 Hz, and a peak of the sound pressure level occurs, but in the first embodiment and these, the resonance at each resonance frequency of 140 Hz, 230 Hz, and 460 Hz. Is suppressed and the peak is reduced. In the conventional example, a clear sound pressure level dip (sound reduction) is observed at 280 Hz. This dip is 250 Hz in the first embodiment and 225 Hz in the first embodiment.
It can be seen that even if the volume of the resonance silencing chamber 2 is the same, the sound is reduced at a lower frequency.

In addition to the above-mentioned actions and effects, in the first embodiment, the structure is simple, so that the manufacturing is easy and the cost can be reduced. The volume ratio between the first chamber 2a and the second chamber 2b can be changed as appropriate, and thus the silencing frequency can be easily set.

Next, in the silencer of the second embodiment shown in FIGS. 4 to 6, the neck 4 has a length of 40 mm, and therefore the communication hole 5 is formed.
Has a length of 43 mm, the intake duct 1 has a sub-communication hole 8 communicating with the second chamber 2b, and the axis of the intake duct 1 is lower than the axis of the resonance silencing chamber 2. 23.5m
It is different from the first embodiment only in that it is shifted by m. The sub communication hole 8 has a length of 3 mm and a diameter of 0 mm (referred to as the second embodiment), 30 mm (referred to as the second embodiment), or 40 mm (referred to as the second embodiment). According to this example, the resonance action (1) of the first example
Since the following action (4) is added to (3), more silencing frequencies can be obtained. (4) Resonance action by the combination of the sub communication hole 8 and the second chamber 2b.

A test similar to that of the first embodiment was conducted on this embodiment. FIG. 6 shows sound pressure levels of frequency components of 500 Hz or less obtained in the test. The broken line in the figure is the same as the comparative example of the first example, the solid line shows the test result of the second example, the one-dot chain line shows the test result of the second example, and the two-dot chain line shows the 2 shows the test results of two examples.

As is apparent from the figure, in the second embodiment, the resonance at 140 Hz of the resonance frequency in the comparative example is suppressed and the peak is reduced, and the peak at 230 Hz shifts to the high frequency side. In the second embodiment and
Similarly, the resonance at 140 Hz, 230 Hz and 460 Hz is suppressed and the peak is reduced. In addition, the apparent sound pressure level dip (sound reduction) is one of 150 Hz in the second embodiment, but is 270 in the second embodiment.
Hz and 450 Hz, 290 Hz in the second embodiment
And 440 Hz appear.

Next, in the muffler of the third embodiment shown in FIG. 7, a sub partition plate 9 which is orthogonal to the partition plate 6 and which passes through the center of the communication hole 5 is provided on the outer surface of the intake duct 1, and both partition walls are provided. The resonance silencing chamber 2 is divided by the plates 6 and 9 into a first chamber 2a, a second chamber 2b, a third chamber 2c and a fourth chamber 2d.
The present embodiment is different from the first embodiment only in that a notch is formed in the upper part of the communication hole 5 and the opening 7 that allows the first chamber 2a to the fourth chamber 2d to communicate with each other. According to this embodiment,
Since the number of divisions of the resonance silencing chamber 2 is larger than that of the first embodiment, the resonance action due to a large number of combinations can be produced correspondingly, and the silencing frequency can be further increased.

The present invention is not limited to the configuration of the above embodiment, and may be embodied by being arbitrarily modified within the scope of the invention, for example, embodying it in a silencer other than an internal combustion engine for automobiles. You can also

[0023]

Since the muffler of the present invention is configured as described above, it is possible to obtain a plurality of muffling frequencies and obtain a sufficient reduction effect even when the frequency range of noise is wide. Since the structure is simple, the manufacturing is easy and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a silencer according to a first embodiment.

FIG. 2 is a sectional view of the sound deadening device.

FIG. 3 is a graph showing an effect of reducing intake noise by the silencer.

FIG. 4 is a perspective view of a silencer according to a second embodiment.

FIG. 5 is a sectional view of the sound deadening device.

FIG. 6 is a graph showing an effect of reducing intake noise by the silencer.

FIG. 7 is a perspective view of a silencer according to a third embodiment.

[Explanation of symbols]

 1 Intake Duct 2 Resonance Silence Chamber 2a 1st Chamber 2b 2nd Chamber 5 Communication Hole 6 Partition Plate 7 Opening

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akemi Nakai 1 Ochiai, Nagachiji, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Within Toyoda Gosei Co., Ltd. Toyoda Gosei Co., Ltd.

Claims (1)

[Claims] 1. A muffler in which a resonance silencing chamber is externally provided on the outer periphery of a flow air duct, wherein a communication hole is formed in the flow air duct in the resonance silencing chamber, and a resonance occurs on the outer circumference of the air flow duct passing through the communication hole. A sound deadening chamber having a partition plate that divides the sound deadening chamber into a first chamber and a second chamber, and the partition plate having a communication hole and an opening that allows the first chamber and the second chamber to communicate with each other. apparatus.