JPH0711931A - Muffler for internal combustion engine - Google Patents

Abstract

PURPOSE:To facilitate replacement of mesh assembly of main parts, simplify its structure, and produce it at a low cost. CONSTITUTION:A mesh unit 28 formed by fixedly arranging two fine meshes 29, which are made of heat-resistant wire covering the whole section of a pipe, to the pipe 28a having a flange 28b on its one end, that is, one mesh arranged to the end of the flange side and the other arranged inside of the pipe at appropriate interval (a distance same as the inside diameter of the pipe or more), is inserted from an exit side of a tail pipe 26 and detachably attached to a muffler main body via the flange part 28b with a small screw.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an exhaust muffler for an internal combustion engine.

[0002]

2. Description of the Related Art An embodiment of a muffler according to the prior art is shown in FIG.
And FIG. 6 will be described. FIG. 5 is a cross-sectional view of a conventional muffler with an extinguishing tool for an engine, and FIG. 6 is a perspective view showing a part of a procedure for making the extinguishing tool. In the muffler 1 with an engine flame extinguishing tool, the inside of a main body 4 is divided into three expansion muffling chambers 7, 8, 9 by partition walls 5, 6. Exhaust gas discharged from the engine (not shown) is introduced into the first expansion and silencing chamber 7 through the inlet pipe 10 as shown by the arrow in FIG. It enters the expansion muffling chamber 8, and further passes through the inside of the second communication pipe 12 and the dust removal layer 13 made of steel wool mat to enter the third expansion muffling chamber 9 so that it is released into the atmosphere from the tail pipe 2. It has become.

In the tail pipe 2, a quenching tool 3 for extinguishing a combustion flame due to an afterfire phenomenon of exhaust gas discharged into the atmosphere is inserted. The extinguisher is
It is formed from a columnar portion 14a formed by winding the wire net 14 and a small diameter portion 14b formed by narrowing one end portion (here, the upper end portion inside the muffler 1) from the periphery, as shown in FIG. In addition, a wire net 14 having a length approximately 1.25 times the length l required for extinction is spirally wound to form a columnar portion 14a, and one end thereof is surrounded by a surrounding portion as shown in FIG. It is made by a procedure in which the small diameter portion 14b is formed by squeezing from it and the small diameter portion 14b is bound by spot welding.

A pin (or a nail) is provided at an intermediate portion of the flame extinguishing tool 3 to prevent uneven distribution of the wire netting 14 due to vibration during use and to make the gaps formed between the spirals of the wire netting 14 uniform. ) 15 is penetrated. This pin 15
Is a flame-extinguishing tool 3 concentrically inserted into the tail pipe 2.
Is fixed to the tail pipe 2 by welding to the inner end surface of the tail pipe 2. In addition, the peripheral wall of the tail pipe 2 has a double wall structure, and a heat insulating material 16 such as glass wool is provided in a space formed between the inner and outer peripheral walls 2a and 2b.
Is filled. Further, the main body 4 is housed in a safety cover 18 which entirely covers the heat insulating space 17 with a space therebetween.

Next, the operation of the conventional example will be described.
In the above configuration, when the exhaust gas advancing from the third expansion muffling chamber 9 to the tail pipe 2 is accompanied by the combustion flame due to the afterfire phenomenon, this exhaust gas is the small diameter portion 14 of the quenching tool 3.
While passing b, the extinguishing tool 3 loses heat and extinguishes the flame.
If there is a combustion flame that passes through here, the exhaust gas flows along the inside of the columnar portion 14a, and the heat is taken by the flame extinguishing tool 3 to be surely extinguished.

Further, since the flame-extinguishing tool 3 is formed by winding the wire net 14, the wire interval forming the wire mesh is much wider than the fiber interval of steel wool, etc.
The flow path resistance given to the exhaust gas flowing inside is significantly reduced.
As a result, it is possible to suppress an increase in back pressure in the muffler 1 and prevent a decrease in exhaust efficiency and thermal efficiency of the engine due to this back pressure, and at the same time, tail of the flame extinguishing tool 3 due to an increase in back pressure in the muffler 1. Blowing from the pipe 2 can be prevented. Further, since the wire forming the wire netting 14 is thicker than the steel fiber forming the steel wool, it is excellent in heat resistance and durability can be enhanced. In addition, the wire net 14 for making the flame-extinguishing tool 3 is much cheaper than a new material such as Celmet, so that the parts cost can be reduced.

[0007]

The above-mentioned conventional example has the following problems. 1) It takes a lot of time and labor for the winding forming of the wire mesh and the assembling to the muffler. 2) A wound wire mesh tends to have a dense central portion of the cross section and a coarse outer peripheral portion, and it is difficult to control the density to a uniform cross section. 3) There is no means for removing the wound wire mesh when it is clogged with scale or the like. 4) Due to the afterfire phenomenon, the wire mesh turns into a red-hot state, and this red color makes the user feel uneasy.

The object of the present invention is to have the same sound deadening characteristic as the conventional one, and when the clogging occurs or the performance deteriorates due to corrosion, the mesh assembly of the main part can be easily replaced, and the structure is simple and the cost is low. It is to provide a muffler for an internal combustion engine that can be manufactured.

[0009]

The muffler of the internal combustion engine of the present invention is inscribed on the outlet side of the tail pipe 26, and the pipe 2
8a is inserted, and is detachably screwed to the muffler body side by a flange 28b provided on the pipe, and the pipe 28a is finely divided into a flange side end and an inside position at an appropriate distance from the same side end position. It is characterized in that the mesh metal mesh 29 is fixed.

[0010]

The exhaust gas expanded and silenced in the expansion / silence chamber is discharged from the tail pipe to the atmosphere, and is further throttled through the pores of the two meshes 29 of the mesh unit 28 in the tail pipe portion, Smooths pressure fluctuations and is rectified to mute noise. According to the experiment, the mesh unit 28 has almost the same silencing ability as that of the conventional example without reducing the engine output, and the inner mesh 29 may be red hot, but the outer mesh 29 may be red hot. It is shown that it will not happen. On the other hand, manufacturing becomes much easier,
Also, clogging and corrosion of the mesh 29 can be dealt with by replacing parts.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a muffler 20 of the present invention, and FIG. 2 is a perspective view of a main part. In these figures, 21 is a muffler body, and the inside is expanded and muffled by partition walls 22 and 24.
It is divided into 2 rooms. (The expansion and silencing chamber is not limited to two). An inlet pipe 25 is connected to the exhaust pipe of an engine (not shown) on the outside. Reference numeral 26 is a tail pipe fixed to the muffler main body 21, and 27 is an annular seat plate fixed to the tip of the tail pipe 26 and has a plurality of female screws (four in the figure) and the outer circumference is two legs. Muffler body 2
It is fixed at 1.

Reference numeral 28 denotes a mesh unit, the outer side of which comprises a pipe 28a which is inscribed and fitted in the tail pipe 26 and a flange portion 28b at the end portion, and the pipe 28a has two disc-shaped meshes (wire mesh). One 29 is fixed to the end on the flange side, and the other 29 is fixed to the inside of the pipe 28a with a space substantially equal to or larger than the inner diameter of the pipe 28a. The mesh 29 has the shape of a lid of a tea canister, and the tubular portion is spot-welded to the pipe 28a. 30 is a small screw for attaching the mesh unit 28,
The female screw of the annular seat plate 27 is screwed through the hole of the flange 28b.

Next, the operation of the muffler having the above structure will be described. Exhaust gas discharged from the exhaust pipe of the engine (not shown) flows from the inlet pipe 25 in the direction of the arrow to
Expansion muffling chamber 23, and then the second expansion muffling chamber 24 repeatedly expands the pressure fluctuations to smooth out the noise and release the sound from the tail pipe 26 to the atmosphere. The pressure fluctuation is smoothed and rectified by the throttling action through the pores of the mesh 29 to muffle the sound. Although various meshes have been conventionally proposed to eliminate the sound of air flow, the two meshes with the intervals shown in this embodiment have the following characteristics.

FIG. 3 shows the noise level when the tail pipe is opened and when a wound wire net, two meshes and one mesh are mounted (index value with 100 when no load 1500 rpm is opened). The results of experiments conducted under three operating conditions are shown. The one equipped with two meshes of the present invention is almost equivalent to the wound wire mesh, and the mesh 1
It has better sound deadening characteristics than the number of sheets. FIG. 4 shows the experimental results of the influence on the engine output when the wound wire mesh and the two meshes are used, respectively, and there is no great difference between the two. Further, in the muffler according to the present invention, the inner mesh may be in a red hot state due to the afterfire phenomenon, but the outer mesh may not be in a red hot state.

[0015]

【The invention's effect】

1) It has a simple structure, is easy to manufacture and assemble, and is low in cost. 2) If the mesh unit becomes clogged or its performance deteriorates due to corrosion, it can be easily replaced. 3) The mesh unit has a flame-extinguishing effect, and the inner mesh may become red hot, but the outer mesh does not become red hot, which does not give the user a feeling of anxiety.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a muffler according to an embodiment of the present invention.

FIG. 2 is a perspective view of the main part.

FIG. 3 is a diagram showing the relationship between muffler type and noise figure.

FIG. 4 is a diagram showing the effect on the output of a wire mesh and a mesh.

FIG. 5 is a sectional view of a muffler showing a conventional technique.

FIG. 6 is a perspective view showing a procedure for making the same flame extinguisher.

[Explanation of symbols]

20 ... Muffler, 21 ... Muffler body, 26 ... Tail pipe, 28 ... Mesh unit, 28a ... Pipe, 28b
… Flange, 29… mesh.

Claims (1)

[Claims] 1. A pipe (28a) is inscribed in an outlet side of a tail pipe (26) of a muffler, and is detachably screwed to a muffler body side by a flange (28b) provided on the pipe. A muffler for an internal combustion engine, characterized in that a fine mesh metal mesh (29) is fixedly provided at positions inside the flange side end and the same side end position of (28a), respectively.