JP3322446B2 - Internal combustion engine muffler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust muffler for an internal combustion engine.

[0002]

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

[0003] A flame extinguisher 3 is inserted into the tail pipe 2 to eliminate the combustion flame of the exhaust gas discharged into the atmosphere due to the after-fire phenomenon. The extinguisher is
As shown in FIG. 6, a columnar portion 14a formed by winding the wire mesh 14 and a small-diameter portion 14b formed by narrowing one end (in this case, the upper end inside the muffler 1) from the periphery thereof are formed. Next, a wire net 14 having a length of about 1.25 times the length l required for quenching is spirally wound to form a columnar portion 14a, and one end of the wire net 14 is formed as shown in FIG. To form a small-diameter portion 14b and bind the small-diameter portion 14b by spot welding.

A pin (or a nail) for preventing the distribution of the wire mesh 14 from being deviated due to vibration during use and equalizing a gap formed between the spirals of the wire mesh 14 is provided at an intermediate portion of the flame extinguishing tool 3. ) 15 is penetrated. This pin 15
Is a flame extinguisher 3 concentrically inserted into the tail pipe 2
Is fixed to the tail pipe 2 by welding to the inner end face of the tail pipe 2. The peripheral wall of the tail pipe 2 has a double wall structure, and a space formed between the inner and outer peripheral walls 2a and 2b has a heat insulating material 16 such as glass wool.
Is filled. Further, the main body 4 is housed in a safety cover 18 that covers the heat insulating space 17 entirely.

Next, the operation of the conventional example will be described.
In the above-described configuration, when the combustion flame due to the afterfire phenomenon accompanies the exhaust gas traveling from the third expansion noise reduction chamber 9 to the tail pipe 2, the exhaust gas is supplied to the small diameter portion 14 of the flame extinguishing tool 3.
The heat is taken off by the flame extinguisher 3 while passing through b, and the flame is extinguished.
If there is a combustion flame passing through here, the exhaust gas flows along the inside of the columnar portion 14a, so that the heat is taken off by the flame extinguishing tool 3 and the flame is surely extinguished.

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

[0007]

The above-mentioned prior art has the following problems. 1) It takes time to perform the work of winding the wire mesh and assembling it to the muffler. 2) The wound wire mesh is dense at the center of the cross section and tends to have a rough density at the outer periphery, and it is difficult to control the density to a uniform cross section. 3) There is no means to remove the wound wire mesh when it is clogged with scale or the like. 4) The wound wire mesh becomes reddish due to the afterfire phenomenon, and this red color gives the user an uneasy feeling.

An object of the present invention is to provide the same silencing characteristics as in the prior art. When clogging occurs or performance deteriorates due to corrosion, it is possible to easily replace the mesh assemblage of the main part, and the structure is simple and low cost. An object of the present invention is to provide a muffler for an internal combustion engine that can be manufactured.

[0009]

A muffler for an internal combustion engine according to the present invention comprises a muffler body (21) and a tail pipe (26).
A muffler for an internal combustion engine having a
The flange (28b) for attachment to the
The muffler book on the inner periphery of the pipe (28a)
Reticulated metal on the inner and outer parts closer to the body (21)
A disk-shaped mesh (29) consisting of
The mesh of the outer part is glowing even if the shoe becomes red hot
Messi installed at intervals so that they do not enter the state
Unit (28) in the tail pipe (26).
It is characterized by being detachably attached to the circumference .

[0010]

The exhaust gas that has been expanded and silenced in the expansion silence chamber is released from the tail pipe to the atmosphere. Pressure fluctuations are smoothed and rectified to mute. According to the experiment, the mesh unit 28 has almost the same silencing ability as the conventional example without lowering the engine output. It is shown not to be. On the other hand, a mesh
A disc-shaped mesh 29 made of an eye-shaped metal is arranged at a predetermined interval.
To form a mesh unit 28 provided side by side.
The brush unit 28 on the inner circumference of the tail pipe 26
Because it is a structure that can be attached to
The manufacture of the hula is much easier, and clogging and corrosion of the mesh 29 can be dealt with by replacing the mesh unit 28 .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment 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, reference numeral 21 denotes a muffler main body, and the inside of the muffler is inflated by a partition wall 22.
Are divided into two rooms. (The expansion muffling chamber is not limited to two chambers). Reference numeral 25 denotes an inlet pipe, the outside of which is connected to an exhaust pipe of an engine (not shown). Reference numeral 26 denotes a tail pipe fixed to the muffler main body 21. Reference numeral 27 denotes an annular seat plate fixed to the tip of the tail pipe 26, which has a plurality of female screws (four in the figure) and has two legs on the outer periphery. Muffler body 2
Fixed to 1.

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

Next, the operation of the muffler having the above configuration will be described. Exhaust gas discharged from an exhaust pipe (not shown) of the engine flows from the inlet pipe 25 in the direction of the arrow, and
The expansion is repeated in the expansion noise reduction chamber 23 and then in the second expansion noise reduction chamber 24 to smooth out the fluctuation of the pressure and muffle the noise, and the noise is released from the tail pipe 26 to the atmosphere. The pressure fluctuation is smoothed and rectified through the pores of the mesh 29 of FIG. Note that meshes of various shapes have conventionally been proposed to suppress airflow noise, but two meshes spaced at the intervals shown in the present embodiment have the following characteristics.

FIG. 3 shows the noise level when the tail pipe is opened and when the wound wire mesh, two meshes, and one mesh are attached, respectively (an index value with 100 when the no-load opening at 1500 rpm). The results of an experiment conducted under three operating conditions are shown. The one equipped with two meshes of the present invention is almost the same as a wound wire mesh.
Has better silencing characteristics than a single sheet. FIG. 4 shows the experimental results of the effect on the engine output when using the wound wire mesh and two meshes, respectively, and there is no significant difference between the two. Also, in the muffler according to the present invention, the inner mesh may be in a glowing state due to the afterfire phenomenon, but the outer mesh will not be in a glowing state.

[0015]

【The invention's effect】1) Is a mesh-like metal on the inner periphery of the pipe 28a
A disk-shaped mesh 29 consisting of
Is formed, and the mesh unit is formed.
When the socket 28 is detachably attached to the tail pipe 26,
Because it is a simple structureEasy to manufacture and assemble, cost
Is cheap.2) The mesh 29 against clogging and corrosion of the mesh 29
This can be dealt with by a simple means of replacing the menu unit 28.  3) Mesh unit has anti-flaming action and internal mesh
The mesh may glow red, but the outer mesh will glow red.
NotThe operator can safely operate the engine.

[Brief description of the drawings]

FIG. 1 is a longitudinal 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 the type of muffler and noise index.

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

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 flame extinguishing tool.

[Explanation of symbols]

20 muffler, 21 muffler main body, 26 tail pipe, 28 mesh unit, 28a pipe, 28b
... flange, 29 ... mesh.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 62-34111 (JP, U) JP-A 56-76113 (JP, U) JP-A 4-8714 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) F01N 1/10

Claims (1)

(57) [Claims] 1. A tail pipe (2) is attached to a muffler body (21).
6) In the muffler of the internal combustion engine with the
Flange (28b) for attachment to the tail pipe (26)
Said muff at the inner periphery of the pipe (28a) to which
Laminate mesh on the inside and outside of the body (21)
A disk-shaped mesh (29) made of metal is
Even if the mesh becomes red hot, the mesh on the outer part
Installed at intervals so that it does not become red hot
Brush unit (28) and the tail pipe (26)
A muffler for an internal combustion engine, which is detachably attached to an inner periphery of the muffler.