JP2003227326A - Muffler of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain back pressure concurrent with expansion effect in a muffler of an internal combustion engine in which an inlet pipe and an outlet pipe are non-axially arranged and an opening is provided at an expansion chamber. <P>SOLUTION: An inlet pipe 10 for taking in exhaust gas to the expansion chamber 9 arranged in the muffler 1 and an outlet pipe 11 for discharging exhaust gas from the expansion chamber are non-axially arranged. At least one of a downstream part 10b of the inlet pipe 10 and an upstream part 11b of the outlet pipe 11 is bent so that a central axis X2 of the downstream part 10b of the inlet pipe 10 and central axis Y2 of the upstream part 11b of the outlet pipe 11 are arranged to be almost parallel. The central axis X2 of the downstream part 10b of the inlet pipe 10 is arranged to point an end of opening of the upstream part 11b of the outlet pipe. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silencer for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as one silencer structure of a silencer provided in an exhaust system of an internal combustion engine, an expansion chamber 102 having a large volume is provided in a silencer 101 as shown in FIG.
Introducing pipe 10 for introducing exhaust gas into the expansion chamber 102
3 and an extension structure including a lead-out pipe 104 for leading out exhaust gas from the extension chamber 102 are known. Although such an expanded structure is an effective sound deadening structure that exerts a sound deadening effect over substantially the entire area of noise, it is also known that back pressure increases due to expansion and contraction of exhaust gas.

Further, when the introduction pipe 103 and the derivation pipe 104 cannot be arranged coaxially due to the mounting layout of the silencer and the space under the floor of the automobile, as shown in FIG. 6, the two pipes 103 and 104 are biased from each other. However, in this case, the back pressure is further increased.

Therefore, as described above, the introduction pipe 103
In an expanded structure in which the outlet pipe 104 is biased, as shown in FIG. 6, as a means for reducing back pressure, a downstream edge 103a of the exhaust gas inlet pipe 103 and an upstream edge 104a of the exhaust gas outlet pipe 104 are provided. Is inclined and cut so as to face each other, and the exhaust gas is guided from the downstream opening end of the introduction pipe 103 to the upstream opening end of the extraction pipe 104 in the expansion chamber 102. It is disclosed in Japanese Utility Model Laid-Open No. 1-118117.

[0005]

However, as described above, the downstream side edge 103a of the introduction pipe 103 and the lead-out pipe 1 are as described above.
Even if the upstream end edge 104a of 04 is inclined and cut, since the exhaust gas flowing in the introduction pipe 103 has straightness, the exhaust gas from the downstream opening end of the introduction pipe 103 is discharged. It flows out without being directed to the upstream open end of the pipe 104. Therefore, the exhaust gas is introduced into the pipe 1
Since it was not smoothly guided from the downstream opening end of No. 03 to the upstream opening end of the outlet pipe 104, the effect of reducing the back pressure was not sufficient.

Therefore, the present invention provides a muffler for an internal combustion engine which can enhance the back pressure reducing effect by smoothly introducing the exhaust gas from the introduction pipe to the extraction pipe in the expansion chamber. The purpose is.

[0007]

In order to solve the above-mentioned problems, the first invention according to claim 1 is to introduce an exhaust gas into an expansion chamber provided in a silencer, and the expansion. In a silencer in which a discharge pipe for discharging exhaust gas from a chamber is arranged non-coaxially, at least one of a downstream portion of the introduction pipe and an upstream portion of the discharge pipe is bent, and a central axis of a downstream portion of the introduction pipe is provided. The internal combustion engine is arranged so that the central axis of the upstream portion of the lead-out pipe is substantially parallel, and the central axis of the downstream portion of the introduction pipe is directed to the open end of the upstream portion of the lead-out pipe. It is the silencer of the engine.

In the present invention, the exhaust gas flowing through the introduction pipe flows into the expansion chamber from the downstream portion of the introduction pipe and is silenced by the expansion action. When this exhaust gas flows out from the downstream portion of the introduction pipe, at least one of the downstream portion of the introduction pipe and the upstream portion of the outlet pipe is bent so that the downstream portion of the inlet pipe is at the open end of the upstream portion of the outlet pipe. Since it is oriented, the exhaust gas flowing out from the downstream portion of the introduction pipe is smoothly guided into the upstream portion of the extraction pipe, and the generation of back pressure due to the expansion action in the expansion chamber is suppressed.

Therefore, in the silencer in which the introduction pipe and the extraction pipe are arranged non-coaxially, the reduction of the back pressure is enhanced.

A second invention according to claim 2 is characterized in that, in the first invention, the central axis of the downstream portion of the introduction pipe and the central axis of the upstream portion of the outlet pipe are substantially coaxial. It is a silencer for an internal combustion engine.

In the present invention, the reduction of the back pressure is further enhanced as compared with the case where the central axis of the downstream portion of the outlet pipe and the central axis of the upstream portion of the outlet pipe are opposed to each other non-coaxially.

A third invention according to claim 3 is the silencer for an internal combustion engine according to the first or second invention, wherein an open end of an upstream portion of the lead-out pipe is flared. Is.

In the present invention, the exhaust gas flowing out from the downstream portion of the introduction pipe is more smoothly introduced into the upstream portion of the extraction pipe by the flare portion to further enhance the reduction of the back pressure and the exhaust gas in the extraction pipe. The generation of airflow noise is suppressed by the flare portion when being guided to.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described with reference to the examples shown in FIGS.

1 and 2 show a first embodiment.

The outer cylinder 2 constituting the muffler 1 is formed of a thin metal plate in a cylindrical shape, in the embodiment shown in the figure, a cylindrical shape, and metal end plates 3 and 4 are appropriately joined by caulking to both ends thereof. It is fixed by means.

A sound absorbing chamber 7 filled with a sound absorbing material 7a is defined by the end plate 3 and a metallic partition plate 5 on the upstream side in the outer cylinder 2, and the end plate 4 is provided on the downstream side. The sound absorbing chamber 8 filled with the sound absorbing material 8a is defined by the partition plate 6 made of metal.

Both of the sound absorbing chambers 7 and 8 in the outer cylinder 2
An expansion chamber 9 is defined by the partition plates 5 and 6 between and.

A metal introduction pipe 10 for introducing exhaust gas into the muffler 1 is arranged through the sound absorbing chamber 7 on the upstream side, and the introduction pipe 10 is provided with a burring portion 3a of the end plate 3. Also, the partition plate 5 is fixed by being inserted into the burring portion 5a of the partition plate 5. Then, the upstream portion 1 of the introduction pipe 10
0 is connected to an exhaust pipe on the upstream side (not shown) so that the exhaust gas is introduced into the introduction pipe 10, and the opening end 10c of the downstream portion 10b of the introduction pipe 10 opens into the expansion chamber 9. Thus, the exhaust gas in the introduction pipe 10 is introduced into the expansion chamber 9.

In the sound absorbing chamber 8 on the downstream side, a metal lead pipe 11 for leading the exhaust gas from the silencer 1 is disposed so as to penetrate therethrough, and the lead pipe 11 is provided with the burring portion 4 of the end plate 4.
a and the burring portion 6a of the partition plate 6 are inserted and fixed. The downstream portion 11a of the outlet pipe 11 is connected to a downstream exhaust pipe (not shown), and the outlet pipe 1
The open end 11c of the upstream portion 11b of No. 1 is opened in the expansion chamber 9 so that the exhaust gas in the expansion chamber 9 is led out to the downstream exhaust pipe through the outlet pipe 11.

Main part 10d of the introduction pipe 10
The center axis X1 of the main body portion 11d of the lead-out pipe 11, that is, the center axis X1 of the main body portion 10d of the lead-in pipe 10 and the center axis Y1 of the main body portion 11d of the lead-out pipe 11 are deviated from each other, and in the illustrated embodiment, the silencer 1 is used. They are set parallel to each other at a predetermined distance from the central axis, that is, in a non-coaxial relationship.

The downstream portion 10b of the introduction pipe 10 and the upstream portion 11b of the extraction pipe 11 are bent so that their central axes X2 and Y2 are substantially coaxial with each other, and the downstream opening of the introduction pipe 10 is provided. The end 10c and the upstream-side open end 11c of the outlet pipe 11 face each other at a substantially central portion of the expansion chamber 9 with a predetermined gap D therebetween, and the open end 10c faces the open end 11c.

The open end 11c of the lead-out pipe 11 is widened to form a flare. The flare portion is indicated by reference numeral 11e.

A large number of small holes 12 are formed in a portion of the lead-in pipe 10 located in the sound absorbing chamber 7, and a large number of small holes 13 are formed in a portion of the lead-out pipe 11 located in the sound absorbing chamber 8. .

In the above structure, the exhaust gas flowing through the exhaust pipe on the upstream side (not shown) is guided into the silencer 1 by the introduction pipe 10, and first, through the small hole 12 formed in the introduction pipe 10, the sound absorbing chamber 7 The sound absorbing material 7a propagates inward, and mainly high-frequency exhaust noise is silenced.

Further, the exhaust gas flows downstream in the introducing pipe 10 and is bent in the traveling direction at the bent downstream portion 10b of the introducing pipe 10 and then enters the expansion chamber 9 through the open end 10c. In the expansion chamber 9, the sound is muted by the expansion action.

When this exhaust gas enters the expansion chamber 9, the exhaust gas is introduced into the downstream portion 10b of the introduction pipe 10.
Since it has straightness along the direction of the central axis X2, it is smoothly guided into the upstream portion 11b of the introduction pipe 11 arranged on the central axis Y2 that is substantially coaxial with the central axis X2, and the back pressure due to the expansion action is Generation is suppressed and back pressure is sufficiently reduced.

Further, in this embodiment, the derivation pipe 1
Since the open end 11c of the upstream portion 11b in No. 1 is flared, the exhaust gas from the introduction pipe 10 is more smoothly guided into the discharge pipe 11, and the effect of reducing back pressure is further enhanced. Moreover, the generation of airflow noise is also suppressed.

As described above, the upstream portion 11 of the outlet pipe 11
The exhaust gas introduced into b is introduced into the main body portion 11d of the lead-out pipe 11, propagates into the sound absorbing chamber 8 through the small holes 13 formed in the main body portion 11d, and is mainly generated by the sound absorbing material 8a. Exhaust noise is silenced.

The exhaust gas flowing through the outlet pipe 11 is led to a downstream exhaust pipe (not shown).

3 and 4 show the second embodiment.

In the second embodiment, the center axis X of the bent downstream portion 10b of the lead-out pipe 10 in the first embodiment is bent.
2 and the center axis Y2 of the bent upstream portion 11b of the lead-out pipe 11 are offset in parallel to each other, and the open end 10c of the downstream portion 10b of the lead-in pipe 10 and the open end 11c of the upstream portion 11b of the lead-out pipe 11 are displaced. At a substantially central portion of the expansion chamber 9 with a predetermined gap D therebetween so as to face each other, and the upstream opening end 10c is connected to the downstream opening end 1.
It is aimed at 1c.

The downstream portion 10 of the introduction pipe 10
When the opening end 10c of the introduction pipe 10 and the opening end 11c of the derivation pipe 11 are projected on the plane Z perpendicular to the central axis X2 of b, as shown in FIG. 4, the projected area of the opening end 10c is smaller than that of the opening end 11c. The positional relationship between both opening ends 10c and 11c is set so as to overlap the projected area by a predetermined amount. This lap portion is shown by a hatched portion L in FIG. The larger the amount of lap, the better, and it is preferably 80% or more.

Since the other structure is the same as that of the first embodiment, the same parts as those described above are designated by the same reference numerals and the description thereof will be omitted.

Also in the second embodiment, by increasing the lap amount, for example, 80% or more, the increase of the back pressure due to the expanding action is suppressed as in the first embodiment, Effective in reducing back pressure.

FIG. 5 shows a third embodiment.

The outer cylinder 22 constituting the muffler 21 has a cylindrical main body portion 23, and an upstream side reduced diameter portion 24 which is tapered at one end thereof coaxially with the central axis X3 of the main body portion 23. On the other end side, it is formed of a metal cylindrical body integrally formed with a downstream side reduced diameter portion 25 which is inclined with respect to the central axis X3 of the main body portion 23 and has a tapered diameter.

A sound absorbing chamber 28 filled with a sound absorbing material 27 is defined by the upstream reduced diameter portion 24 and a metal partition plate 26 on the upstream side in the outer cylinder 22, and on the downstream side, the sound absorbing chamber 28 is formed. An expansion chamber 29 is defined by the downstream-side reduced diameter portion 25 and the partition plate 26.

A metal introduction pipe 30 for introducing exhaust gas into the silencer 1 is disposed through the sound absorbing chamber 28, and the introduction pipe 30 is separated from the neck portion 24a formed in the upstream reduced diameter portion 24. Burring portion 26a formed on the plate 26
It is fixed by being inserted into. And the introduction pipe 30
Is connected to an upstream exhaust pipe (not shown) so that exhaust gas is introduced into the introduction pipe 30, and the open end 30c of the downstream portion 30b of the introduction pipe 30 is connected to the expansion chamber 29. Exhaust gas is opened in the expansion chamber 2
It will be introduced in the 9th.

In the expansion chamber 29, the exhaust gas silencer 2
A metal-made lead-out pipe 31 that is led out from the No. 1 is arranged, and the lead-out pipe 31 is fixedly inserted through a neck portion 25a formed in the downstream side reduced diameter portion 25 of the outer cylinder 22. And
The downstream portion 31a of the outlet pipe 31 is connected to a downstream exhaust pipe (not shown), the open end 31c of the upstream portion 31b of the introduction pipe 31 is opened in the expansion chamber 29, and the exhaust gas in the expansion chamber 29 is opened. Is led out to the exhaust pipe on the downstream side through the lead-out pipe 31.

The main body portion 31d of the introduction pipe 30 and the lead-out pipe 31, that is, the central axis X3 of the introduction pipe 30 and the central axis Y3 of the main body portion 31d of the lead-out pipe 31 are inclined to each other and set in a non-coaxial relationship. Has been done.

The upstream portion 31b of the outlet pipe 31 is
The central axis Y4 is bent so as to be substantially coaxial with the central axis X3 of the introducing pipe 30, and the downstream opening end 30c of the introducing pipe 30 and the upstream opening end 31 of the outlet pipe 31.
In the expansion chamber 29, c are separated by a predetermined space D and face each other, and the open end 30c is directed to the open end 31c.

The open end 31c of the lead-out pipe 31 is expanded and formed in a flare shape. The flare portion is indicated by reference numeral 31e.

A large number of small holes 32 are formed in the portion of the introduction pipe 30 located in the sound absorbing chamber 28.

Also in the third embodiment, the same effect as that of the first embodiment is exerted, and the effect of suppressing the increase in back pressure due to the expanding effect similar to that described above is suppressed, and the effect of increasing the reduction of back pressure is exerted.

Also in the third embodiment, as in the second embodiment, the central axis X3 of the downstream portion 30b of the introduction pipe 30 and the central axis Y4 of the upstream portion 31b of the extraction pipe 31 are deviated from each other. Alternatively, the opening ends 30c and 31c may be overlapped with each other by a predetermined amount on the projection surface.

In each of the above-described embodiments, the main body of the introduction pipe and the main body of the outlet pipe have a positional relationship in which they are biased or inclined with respect to each other, but there is a non-coaxial relationship other than this relationship. In this case, the present invention can be applied even in the case of a twisted positional relationship.

[0048]

As described above, according to the first aspect of the present invention, in the silencer in which the introduction pipe and the extraction pipe are arranged non-coaxially, the back pressure due to the expansion action can be sufficiently reduced. You can

According to the second aspect of the invention, the back pressure reducing effect can be further enhanced.

According to the third aspect of the invention, the back pressure reducing effect can be further enhanced, and the generation of airflow noise can be suppressed.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

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

FIG. 4 is a diagram in which an opening end of a downstream portion of the introduction pipe and an opening end of an upstream portion of the extraction pipe are projected on a projection surface Z in the embodiment of FIG.

FIG. 5 is a side sectional view showing a third embodiment of the present invention.

FIG. 6 is a side sectional view showing a conventional silencer.

[Explanation of symbols]

1,21 silencer 9,29 Expansion room 10,30 introduction pipe 11,31 Derivation pipe 10b, 30b Downstream of the introduction pipe 11b, 31b upstream of the outlet pipe 10c, 11c, 30c, 31c Open end 11e, 31e flare part X1, X3 central axis of introduction pipe Y1, Y3 Central axis of the outlet pipe X2, X3 Central axis of the downstream part of the outlet pipe Y2, Y4 Central axis of upstream part of outlet pipe

Claims (3)

[Claims] 1. A silencer in which an introduction pipe for introducing exhaust gas into an expansion chamber provided in the muffler and a discharge pipe for discharging exhaust gas from the expansion chamber are arranged non-coaxially. At least one of the downstream portion and the upstream portion of the outlet pipe is bent, and the central axis of the downstream portion of the inlet pipe and the central axis of the upstream portion of the outlet pipe are arranged to be substantially parallel to each other, and A silencer for an internal combustion engine, wherein a central axis of the downstream portion is directed toward an opening end of the upstream portion of the outlet pipe. 2. The silencer for an internal combustion engine according to claim 1, wherein the central axis of the downstream portion of the introduction pipe and the central axis of the upstream portion of the outlet pipe are substantially coaxial. 3. The silencer for an internal combustion engine according to claim 1, wherein an open end of an upstream portion of the lead-out pipe is flared.