JP2003269129A - Engine muffler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the noise reduction performance of a muffler without changing its outside dimension. <P>SOLUTION: The engine muffler 10 has a cross section to be fixed with a tubular supporting pipe 20. The base end of the supporting pipe 20 is blocked with a plug 20A and the end thereof is opened to an internal space of the muffler 10 to form the supporting pipe 20 as a resonator with a noise reduction function. Thus, a given space is utilized to the maximum without changing the outside dimension of the muffler 10 to improve the noise reduction performance. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine silencer for reducing exhaust noise, and more particularly to a technique for improving silence performance without changing the outer dimensions of the silencer.

[0002]

2. Description of the Related Art In vehicles such as automobiles, it is well known that exhaust noise is reduced by a silencer provided in an exhaust passage. In a tractor that pulls a trailer, a silencer that is attached and fixed to a side member that constitutes a frame is generally used because of a vehicle layout.

As shown in FIG. 4, such a muffler functions as a casing 1, a first partition plate 2 and a second partition plate 3 for partitioning the interior of the casing 1 into a plurality of spaces, and a mounting member for a side member. And a support tube 4 that operates. As a fixing form of the support tube 4, as shown in FIG. 4 (A), the supporting pipe 4 is fixed in a state of penetrating one side wall of the casing 1 and in contact with the first partition plate 2, FIG. 4 (B). As shown, there is a case in which the casing 1, the first partition plate 2, and the second partition plate 3 are all fixed in a state of penetrating.

[0004]

By the way, in recent years,
In order to deal with exhaust noise that increases with the improvement of engine output, the silencer tends to become larger and larger in order to secure a sufficient internal space volume that contributes to silence. However, the space in which the silencer can be mounted in the vehicle is limited, and there is a limit to increasing the size of the silencer. Therefore, it is required to improve the silencing performance by maximizing the use of the given space without changing the external dimensions of the silencer.

In view of the above-mentioned conventional problems, the present invention provides a vehicle in which the silencer mounting member has a silencing function to improve the silencing performance without changing the outer dimensions of the silencer. The purpose is to provide a muffler for use.

[0006]

Therefore, in the invention of claim 1, in the engine silencer in which the cross section is fixed by the tubular support tube, the base end portion of the support tube is closed, and It is characterized in that the tip end is opened to the internal space of the silencer for engine, and the support tube is configured as a resonator having a silencing function.

According to this structure, the support tube for fixing the engine silencer acts as a resonator exhibiting a silencing function. Therefore, the silencing performance of the engine silencer is improved by maximizing the use of the given space without changing the external dimensions. According to a second aspect of the present invention, in a muffler for an engine in which a cross section is fixed by a tubular support pipe, both ends of the support pipe are closed, and an intermediate portion thereof is provided with a hole having a predetermined cross-sectional area. The engine silencer is opened to the internal space, and the support tube is configured as a Helmholtz resonator having a silencing function.

According to this structure, the support tube for fixing the silencer for the engine functions as a Helmholtz resonator exhibiting a silencing function. Then, the resonance frequency according to the size of each part of the support tube as the Helmholtz resonator is attenuated,
The exhaust noise based on this resonance frequency is reduced. Therefore, the silencing performance of the engine silencer is improved by maximizing the use of the given space without changing the external dimensions.

The invention according to claim 3 is characterized in that a small tube having a predetermined cross-sectional area and a predetermined length is connected to a small hole formed in an intermediate portion of the support tube. With such a configuration, the resonance frequency of the Helmholtz resonator can be easily changed by changing the size of each part of the small cylinder, and the tuning according to the resonance frequency to be silenced becomes easy.

According to a fourth aspect of the present invention, the resonance frequency is tuned by adjusting the size of each part of the support tube according to the resonance frequency at which the sound is to be silenced.
With such a configuration, it is possible to optimize the muffling characteristics in accordance with a frequency range where the exhaust noise is particularly large, and it is possible to maximize the muffling performance.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an overall configuration in which the present invention is applied to a silencer for an engine of an automobile (hereinafter referred to as “muffler”) as a first embodiment of the present invention. The muffler 10 interposed in the exhaust passage is formed in a substantially rectangular outer shape, and is provided with an exhaust introduction pipe 12 for introducing the exhaust and an exhaust introduction pipe 14 for extracting the exhaust. The exhaust introduction pipe 12 is connected to an exhaust pipe 16 connected to an exhaust manifold (not shown), while the exhaust outlet pipe 14 is connected to a tail pipe (tail pipe) 18 for discharging exhaust gas to the atmosphere.

Further, as shown in FIG. 2, a support pipe 20 functioning as a mounting member for fixing to the vehicle body is fixed to the muffler 10. The support tube 20 is formed in a tubular shape in its cross section, and is formed on one side wall of the casing 10A and the first side wall.
The partition plate 10B is fixed by welding or the like while penetrating the partition plate 10B. Then, as shown in FIG. 1, in the muffler 10, the tip end portion of the support tube 20 is fitted and fastened to the mount bracket 24 fixed to the outer surface of the side member 22 of the vehicle.
It is rigidly fixed to the vehicle body.

Here, as a feature of the present invention, the support tube 20 is provided.
Is opened at its tip into the intermediate space 10H,
The base end of the mount bracket 24 is closed by the plug 20A. According to this structure, the support tube 20 acts as a side branch type resonator,
It is possible to improve the silencing performance by providing the silencing function to the. For this reason, it is possible to improve the sound deadening performance by maximizing the use of the given space without changing the outer dimensions of the muffler 10.

Here, by changing the dimensions of each part of the support tube 20, that is, the effective length in the axial direction, the tube diameter, etc., the support tube 2
It is desirable to tune the resonance frequency related to the muffling characteristic produced by 0. In short, by adjusting the size of each part of the support pipe 20 according to the resonance frequency to be silenced, the silencing characteristics can be optimized in accordance with the frequency range where the exhaust noise is particularly large, and the silencing performance can be maximized. be able to. The tuning may be performed by closing the tip of the support tube 20 with a plug to form a small hole, or by connecting a tubular small tube to the tip.

FIG. 3 is a sectional view of a muffler showing a second embodiment of the present invention. In the present embodiment, unlike the first embodiment described above, the support pipe 26 is fixed while penetrating both side walls of the casing 10A, the first partition plate 10B, and the second partition plate 10C. The front end and the base end of the support tube 26 are closed by the plugs 26A and 26B, respectively. In addition, it is the intermediate wall of the support tube 26 and the intermediate space 1
A hole 26C having a predetermined cross-sectional area is formed in a portion in contact with 0H, and a cylindrical small tube (resonator pipe) 26D having a predetermined cross-sectional area and a predetermined length is connected thereto.

According to this structure, the support tube 26 functions as a Helmholtz resonator, and the support tube 26 has a sound deadening function, whereby the sound deadening performance can be improved. For this reason, it is possible to improve the sound deadening performance by maximizing the use of the given space without changing the outer dimensions of the muffler 10. The Helmholtz resonator has a structure having a small tubular inlet and a space inside, and constitutes a resonance system having one degree of freedom (single resonance system having one resonance frequency) like a mechanical spring-mass system. . In this system, the air at the inlet (neck) acts as a mass, and does not generate a wave in a cavity smaller than the wavelength, but acts as a spring. The resonance frequency f ₀ [Hz] is calculated by the following equation.

[0017]

[Equation 1] Here, S is the cross-sectional area [m ₂ ] of the neck (small cylinder 26D),
V is the volume [m ₃ ] of the cavity (support tube 26), and c is the speed of sound [m
/ S], 1 is the neck length [m], and δ is the tube end correction. The execution length l + δ is used instead of the neck length l because the air near both ends of the neck is also moved at the same time. In the case of a small cylinder whose neck has a radius of d [m], the pipe end correction δ is about 0.85d.

When a sound wave is incident on the Helmholtz resonator,
At the resonance frequency, the amplitude of the air in the neck becomes large, friction occurs, the energy near the resonance frequency is attenuated, and the silencing function is exerted. Note that, also in this embodiment, as in the first embodiment, the silencing characteristics can be tuned by changing the dimensions of each part of the support tube 26 (including the small cylinder 26D) that constitutes the Helmholtz resonator. desirable.

Further, the first embodiment and the second embodiment described above
Although the muffler is fixed by one supporting tube in the embodiment, the muffler may be fixed by a plurality of supporting tubes. In this case, if the sizes of the support tubes are made different, the silencing function can be exhibited for a plurality of resonance frequencies. Further, it goes without saying that the muffler according to the present invention can be applied to mufflers other than automobiles, for example, marine engines, engines for industrial equipment, and the like.

[0020]

As described above, according to the invention of claim 1 or 2, the silencer for an engine can be used to its maximum extent without changing the outer dimensions of the silencer. The performance can be improved. According to the invention described in claim 3, the resonance frequency of the Helmholtz resonator can be easily changed by changing the size of each part of the small cylinder.
The muffling characteristics can be tuned optimally.

According to the fourth aspect of the present invention, the silencing characteristics can be optimized in accordance with the frequency range where the exhaust noise is particularly large, and the silencing performance can be maximized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment in which the present invention is applied to a muffler of an automobile.

FIG. 2 is a sectional view of a muffler according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a muffler according to a second embodiment of the present invention.

FIG. 4 shows a conventional muffler mounting structure, (A) is a sectional view of the first embodiment, and (B) is a sectional view of the second embodiment.

[Explanation of symbols]

10 muffler 20 Support tube 20A plug 26 Support tube 26A plug 26B plug 26C hole 26D small tube

Claims (4)

[Claims] 1. A silencer for an engine having a tubular cross section fixed by a support pipe, wherein the base end portion of the support pipe is closed and the tip end portion thereof is opened to the internal space of the silencer for engine. A silencer for an engine, characterized in that the support tube is configured as a resonator having a silencing function. 2. An engine silencer having a tubular cross section fixed by a support pipe, wherein both ends of the support pipe are closed, and an intermediate portion of the silencer for engine is provided with a hole having a predetermined cross-sectional area. A silencer for an engine, characterized in that the support tube is opened to an internal space of the vessel and the support tube is configured as a Helmholtz resonator having a silencing function. 3. A small hole formed in an intermediate portion of the support tube,
The muffler for an engine according to claim 2, wherein a small cylinder having a predetermined cross-sectional area and a predetermined length is connected. 4. The engine according to claim 1, wherein the resonance frequency is tuned by adjusting the size of each part of the support tube according to the resonance frequency to be silenced. Silencer for.