JPH1182002A - Muffler device for two-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve purification performance and prevent output characteristics from being affected. SOLUTION: An exhaust chamber 2 for a two-cycle engine to be connected to a rear end of an exhaust pipe 1 is composed of a divergent cone part 6, an intermediate part 7 and a convergent cone part 8. A first catalyst cylinder 11 and a second catalyst cylinder 12 are arranged axially in line inside the exhaust chamber 2. An opening 12 is formed on a rear part side wall surface of the convergent cone part 8, on the further rear side of the rear end of the second catalyst cylinder 12. A leading end of a tail pipe 3 is connected thereto, so as not to be projected inward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a muffler device for a two-cycle engine.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. Sho 62-1380 discloses a muffler device for a two-stroke engine. This muffler device has a tail pipe extending from the inside of an intermediate portion of an exhaust chamber to the outside through an outer peripheral portion. Is provided.

Further, Japanese Patent Application Laid-Open No. 8-135436 discloses a muffler device for a two-cycle engine, which also has a communication pipe extending outward from an intermediate portion of the exhaust chamber. This communication pipe is separate from the exhaust chamber. A purified exhaust gas is discharged from a tail pipe provided in the catalyst tube connected to the body of the catalyst tube.

[0004]

SUMMARY OF THE INVENTION Incidentally, Japanese Patent Application Laid-Open No.
There is a case where it is desired to integrate the catalyst cylinder with the exhaust chamber without separating the catalyst cylinder as in JP-A-135436. In this case, for example, a catalyst is provided in the exhaust chamber as in JP-B-62-1380, and The front end of the tail pipe will be connected near the part.

However, in this case, the exhaust gas before being completely purified by the catalyst may be exhausted from the tail pipe, and the purification performance may not be improved.
In addition, if the tail pipe protrudes into the exhaust chamber, it may promote the blow-through of the exhaust gas, thereby promoting the reduction of the purification performance.

[0006]

In order to solve the above-mentioned problems, the present invention provides an exhaust chamber connected to the rear end of an exhaust pipe extending from an exhaust port of a two-cycle engine, and a tail extending from the exhaust chamber. In a muffler device for a two-stroke engine including a pipe and a catalyst provided in an exhaust chamber, an opening is formed in an outer peripheral side surface of an exhaust chamber, which is located rearward of exhaust from a rear end of the catalyst, and is formed in the opening. The front end of the tail pipe is connected.

[0007]

According to the present invention, since an opening is provided in the outer peripheral portion of the exhaust chamber and the front end of the tail pipe is connected to the opening, the exhaust gas travels in the exhaust chamber along the axial direction thereof while the catalyst flows. After being sufficiently contacted with the catalyst, it is purified, further reflected at the convergent portion and reacts with the catalyst again, reaches the opening in the outer peripheral portion, and is discharged out of the exhaust chamber.

[0008] Therefore, the exhaust gas reaches the opening after completely passing through the portion where the catalyst is provided, and is sufficiently purified during this time to improve the purification performance. In addition, since the tail pipe is connected to the outer peripheral side surface at the rear part of the exhaust chamber, it is possible to prevent exhaust gas from being insufficiently blown, thereby improving purification performance.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a muffler device for a two-stroke engine configured for a motorcycle will be described below with reference to the drawings. FIG. 1 is a side sectional view showing the side surface of the muffler device in cross section, FIG. 2 is a plan sectional view showing the plane side thereof in cross section, FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, and FIG. FIG. 5 is a cross-sectional view taken along line 5-5, FIG. 6 is a cross-sectional view taken along line 6-6, FIG. 7 is a partially cutaway view of the vicinity of the support portion of the first catalyst cylinder, and FIG. It is the same figure of a catalyst cylinder.

1 and 2, the muffler device includes an exhaust pipe 1, an exhaust chamber 2, and a tail pipe 3. The exhaust pipe 1 has a front end connected via a joint fitting 4 to the exhaust of a two-cycle engine (not shown). A curved pipe member that is connected to the mouth and has a rear end connected to the front end of the exhaust chamber 2. The left and right halves divided along the axial direction are integrated with each joint flange 5. .

The exhaust chamber 2 has a divergent cone portion 6 which is tapered so as to gradually increase in diameter rearward.
And an intermediate portion 7 having a substantially constant pipe diameter at the maximum diameter, and a convergent cone portion 8 having a tapered shape so as to gradually reduce the diameter from the rear thereof, and the rear end of the convergent cone portion 8 is a closed portion. It is 9.

The exhaust chamber 2 is also one in which the right and left halves divided along the axial direction are integrated by each joining flange 10. However, in the exhaust pipe 1 and the exhaust chamber 2, the positions of the joining flanges 5 and 10 are changed by 90 degrees from each other.
FIG. 2 is a diagram cut along the joining surface of the joining flange 5, and FIG. 2 is a diagram cut along the joining surface of the joining flange 10.

A first catalyst cylinder 11 and a second catalyst cylinder 12 are provided in series in the front-rear direction in the axial direction of the inside of the exhaust chamber 2, and are respectively supported on the inner wall of the exhaust chamber 2 by support plates 13 to 15. The exhaust gas flows while contacting the inner and outer surfaces of each catalyst tube.

In the vicinity of the entrance to the convergent cone portion 8 connected to the rear end of the intermediate portion 7, an opening 16 penetrating the inside and outside of the tube wall is formed, and the position of the opening 16 is the second position. Is located further rearward than the rear end of the catalyst tube 12 and below the middle in the vertical direction of the exhaust chamber 2 in a side view.

As is apparent from FIG. 3, the periphery of the opening 16 on the outer surface side of the convergent cone portion 8 is surrounded by a joint pipe 17. One end of the John int pipe 17 is in contact with the outer surface of the convergent cone portion 8 around the opening 16, the other end protrudes outward, and the tip 18 of the tail pipe 3 is fitted to the other end. And hermetically welded.

The inside of the convergent cone portion 8 has a double wall structure in which an inner wall 21 of a punching material is attached with a sound deadening material 20 interposed therebetween. It is not formed in the portion where the portion 16 is provided.

As shown also in FIGS. 4 and 7, the first catalyst cylinder 11 is formed by appropriately punching a metal punching plate made of stainless steel or the like into a cylindrical shape and carrying a known catalyst 22 on the inner and outer surfaces thereof. The front end extends to the inside of the exhaust pipe 1, and the rear end is inserted into the front end of the second catalyst tube 12. The thickness of the catalyst 22 in the figure is greatly exaggerated.

At the rear of the first catalyst tube 11, the support plate 1
A collar 23 is attached all around the outer periphery of the portion supported by 3. As is apparent from FIG.
Is divided in the front-rear direction, the catalyst 22 is also carried on each surface, and an engagement piece 24 is formed so as to protrude radially outward from each adjacent end.

Around the collar 23, a heat-resistant elastic body 25 having a structure rich in elasticity by knitting a mesh-like metal such as stainless steel as appropriate is wound in a band shape, and a holder 26 is further placed thereon. It is fixed by.

The holder 26 is composed of a pair of halves having a substantially semicircular cross section, and the positioning holes 2 formed in the side surfaces of the halves.
7 is formed into an integral ring by inserting the tip of the locking piece 24 and welding the adjacent ends of the halves.

The periphery of the holder 26 is welded to the support plate 13 as shown in FIG.
3 has both ends welded to the inner wall thereof across the divergent cone portion 6. As a result, the first catalyst cylinder 11 is supported in a floating manner into the divergent cone section 6 via the elastic body 25. The material and structure of the elastic body 25 are not limited to the present embodiment.

The second catalyst tube 12 has a structure similar to that of the first catalyst tube 11, and is formed by forming a perforated plate of a suitable metal such as stainless steel into a cylindrical shape and carrying a known catalyst 22 on the inner and outer surfaces thereof. Is disposed between the front end of the divergent cone portion 6 and the intermediate portion 7 longer than the first catalyst tube 11, and is supported by support plates 14 and 15 at two front and rear portions.

As is apparent from FIGS. 8, 5 and 6, the front and rear support portions are respectively a collar 30 and an elastic body 31.
And a holder 32, each of which is a first catalyst cylinder 1
1 has substantially the same structure as the collar 23, the elastic body 25, and the holder 26, except that the collar 30 and the elastic body 31 are provided one by one for each supporting portion, and the catalyst 3 is also provided on the surface of the collar 30.
3 is being carried.

FIG. 6 shows the end face shape of the holder 32. The positioning claws 34 are bent from the axial end of the holder 32 in the inner circumferential direction. The same applies to each of the holders 26 and 32 in the first catalyst tube 11. The intermediate section 7 also has a double wall structure similar to that of the convergent cone section 8, which is indicated by a common symbol.

Next, the operation of this embodiment will be described. The exhaust gas flowing through the exhaust pipe 1 from the two-cycle engine is
Into the exhaust chamber 2 through the inside and outside of the catalyst tube 11
Further, the gas flows rearward inside and outside the second catalyst tube 12.

At this time, the catalyst is purified by coming into contact with the catalyst 22 carried on the first catalyst tube 11 and the second catalyst tube 12, and is converted after passing through the entire length of the second catalyst tube 12. The light is reflected by the gentle cone 8 and reacts with the catalyst again.
Since it is formed on the side wall of the convergent cone portion 8 located at a position further rearward, it is discharged from the opening 16 to the outside through the tail pipe 3.

Therefore, the exhaust gas is supplied to the first catalyst cylinder 1
The entire range of contact with the catalyst 22 carried by the first and second catalyst cylinders 12 can be achieved, and the entire purification capability of the first catalyst cylinder 11 and the second catalyst cylinder 12 can be sufficiently exhibited. As a result, purification performance is improved.

In addition, since the opening 16 to which the tail pipe 3 is connected is formed in the side wall of the convergent cone portion 8, the amount of exhaust gas flowing into the tail pipe 3 at a stage where purification is insufficient can be reduced, and Even after being reflected by the convergent cone section 8, the catalyst can react with the catalyst again, so that the purification performance is also improved in these respects.

Further, the tail pipe 3 is connected to the exhaust chamber 2
By not protruding inward, exhaust pulsation in the exhaust chamber 2 is not hindered, so that the possibility of adversely affecting the output characteristics of the two-cycle engine is reduced.

Further, the tail pipe 3 is connected to the exhaust chamber 2.
Is connected to the joint pipe 17 welded to the outer periphery of the exhaust pipe 2 so that the tail pipe 3 can be easily connected so as not to protrude into the exhaust chamber 2. However, the front end of the tail pipe 3 is directly welded to the exhaust chamber 2 around the opening 16, or the front end of the tail pipe 3 is inserted into the opening 16.
And may be welded by being inserted so as to be flush with the inner surface.

Since the opening 16 is provided below the rear end of the second catalyst tube 12 in a side view, carbon in relatively heavy exhaust gas can be quickly discharged to the tail pipe 3. And the amount of carbon remaining in the exhaust chamber 2 can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a muffler device according to an embodiment.

FIG. 2 is a plan sectional view thereof.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 of FIG.

FIG. 5 is a sectional view taken along line 5-5 of FIG.

FIG. 6 is a sectional view taken along line 6-6 of FIG.

FIG. 7 is a partially cutaway view showing the vicinity of a support portion of a first catalyst cylinder.

FIG. 8 is a partially cutaway view showing the vicinity of a support portion of a second catalyst tube.

[Explanation of symbols]

1: exhaust pipe, 2: exhaust chamber, 3: tail pipe,
6: divergent cone portion, 7: middle portion, 8: convergent cone portion, 11: first catalyst tube, 12: second catalyst tube, 16: opening

Claims (1)

[Claims] An exhaust chamber connected to a rear end of an exhaust pipe extending from an exhaust port of a two-stroke engine, a tail pipe extending from the exhaust chamber, and a catalyst provided in the exhaust chamber are provided. A muffler device for a two-cycle engine, characterized in that an opening is formed in the outer peripheral side surface of the exhaust chamber behind the rear end of the catalyst and the front end of a tail pipe is connected to the opening. Muffler device for engine.