JP3201964B2 - Exhaust device catalyst device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst device for an exhaust device, and more particularly to a catalyst device suitable for an exhaust device of a multiple cylinder engine.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional exhaust device for a two-cylinder engine for a motorcycle, in which a plurality of exhaust pipes 2 connected to respective exhaust ports of an engine 1 are assembled into a collecting pipe 3, and the collecting pipe 3 is provided. An exhaust muffler 6 is connected to 3 via a joint pipe 5. As a related technique, there is JP-A-7-305624.

In the exhaust muffler 6, a first expansion chamber 11, an outlet chamber 13 and a second expansion chamber 1 are arranged in this order from the joint pipe 5 side.
In the case of a two-wheeled vehicle, it is difficult to arrange the catalyst section in each narrow exhaust pipe 2 in terms of space. Therefore, the catalyst section 4 is fixed to the exhaust muffler 6. As the catalyst portion 4, a metal honeycomb type formed by spirally forming a plate obtained by firing platinum and rhodium, for example, is fitted.

[0004] As for the location of the catalyst section 4, considering that a sufficient temperature for activating the catalyst can be secured and that the arrangement is easy, the collecting section (inlet end) 3 a of the collecting pipe 3 is considered.
However, in order to secure a sufficient amount of exhaust gas flow and suppress a decrease in output performance, the exhaust muffler 6 having a large flow cross-sectional area as described above is suitable. The catalyst section 4 is often disposed in the first expansion chamber 11 which is the most upstream side thereof.

[0005]

However, in general, the joint pipe 5 is formed of stainless steel, while the exhaust muffler 6 is made of a member different from the joint pipe 5 such as an aluminum alloy in order to improve the appearance. In the structure in which the catalyst section 4 is directly installed and supported on the exhaust muffler 6, the reaction heat of the catalyst section 4 directly affects the exhaust muffler 6 made of an aluminum alloy, which may lead to discoloration or shortening of the life.

Further, in the structure in which the catalyst unit 4 is provided directly in the exhaust muffler 6, the replacement of the catalyst unit 4 takes time and effort.
In some cases, the entire exhaust muffler needs to be replaced in order to replace the catalyst unit 4.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the life of an exhaust muffler and facilitate replacement of a catalyst section.

[0008]

In order to achieve the above object, according to the present invention, a plurality of exhaust pipes 2 extending from respective exhaust ports of an engine 1 are connected via a collecting pipe 3 and a joint pipe 5. An exhaust device that is assembled to the exhaust muffler 6 includes a joint pipe 5 that is formed of a separate member from the exhaust muffler 6 and that forms an exhaust passage between the collecting pipe 3 and the exhaust muffler 6. A cylindrical portion 13 having a diameter larger than the inner diameter of the joint pipe 5 is provided at the side end.
a, the catalyst portion 8 is fitted into the enlarged tubular portion 13a, an outward flange 20 is provided at a portion of the joint pipe 5 upstream of the tubular portion 13a on the exhaust side, and an exhaust inlet side of the exhaust muffler 6 is provided. An opening 2 through which the cylindrical portion 13a can be inserted and removed
2, the cylindrical portion 13a containing the catalyst portion 8 is inserted into the exhaust muffler 6 through the opening 22, and the flange 20 is brought into contact with the inlet-side end wall of the exhaust muffler 6, thereby forming the flange 20 and the exhaust muffler. It is characterized in that it is detachably connected to the inlet side end wall.

According to a second aspect of the present invention, in the catalytic device of the exhaust system according to the first aspect, a tapered portion 13 whose diameter increases toward the downstream of the exhaust is provided at the end of the joint pipe 5 on the downstream of the exhaust. The catalyst portion 8 is fitted into a large-diameter cylindrical portion 13a formed at the exhaust downstream end of the tapered portion 13, and an outward flange is provided on the joint pipe 5 portion upstream of the tapered portion 13. 20 is provided. According to a third aspect of the present invention, in the catalyst device of the exhaust system according to the first or second aspect, the catalyst portion is a metal honeycomb type.

[0010]

FIG. 1 shows an exhaust system for a two-cylinder engine for a motorcycle to which the present invention is applied.
A plurality of exhaust pipes 2 connected to each exhaust port of
And an exhaust muffler 6 connected to the collecting pipe 3 via a joint pipe 5. The internal structure of the exhaust muffler 6 is the same as in FIG. 6, and is omitted in FIG. The joint pipe 5 is made of stainless steel, and a plate-like separator 10 for dividing the exhaust passage into two upper and lower exhaust passage portions is disposed inside the joint pipe 5.

FIG. 3 is an exploded enlarged vertical sectional view taken along the arrow II of FIG. 1. A tapered portion 13 whose diameter increases as it goes rearward is integrally formed at the rear end of the joint pipe 5. , The flange 2 slightly upstream from the tapered portion 13
0 is provided integrally, and a metal honeycomb type catalyst part 8 formed by spirally forming a stainless steel plate obtained by firing a catalyst material such as platinum and rhodium on a cylindrical part 13 a downstream of the tapered part 13. Is fitted.

The exhaust muffler 6 is made of, for example, an aluminum alloy material.
Opening 2 large enough for easy insertion and removal of tapered portion 13
2 are formed, and the nut part 25 is fixed. As shown in FIG. 2, the taper portion 13 is inserted into the exhaust muffler 6 from the front, and the bolt 23 inserted into the bolt insertion hole of the flange 20 is screwed into the nut portion 25 of the exhaust muffler 6, thereby making the exhaust muffler 6 The joint pipe 5 is detachably attached.

The flow of exhaust gas will be described briefly. In FIG. 1, the exhaust gas discharged from each exhaust port of the engine 1 to each exhaust pipe 2 is collected in a collecting pipe 3 and flows to an exhaust muffler 6 through a joint pipe 5. When the gas flows from the joint pipe 5 into the exhaust muffler 6, it passes through the catalyst section 8, so that the exhaust gas is purified at this time.

In FIG. 2, at the rear end of the joint pipe 5, a tapered portion 13 whose flow cross-sectional area is gradually increased.
Thus, the entire surface of the catalyst section 8 can be effectively used as an exhaust gas purification surface, and the catalyst function is improved.

[0015]

[Reference Example] FIG. 4 shows an example of a structure for mounting the joint pipe 5 using the flange 20 as a reference.
The cylindrical catalyst part 17 is directly welded. Cylindrical catalyst part 1
Reference numeral 7 is made of stainless steel, and as shown in FIG. 5, its cross-sectional shape is formed in a gear shape having a number of round convex portions, and a catalyst material such as platinum and rhodium is fired on both inner and outer surfaces thereof. is there.

When the joint pipe 5 is attached to the exhaust muffler 6, the rear end catalyst portion 17 of the joint pipe 5 is attached to the exhaust muffler 6 from the front as in the case of FIGS.
The joint pipe 5 is detachably attached to the exhaust muffler 6 by screwing a bolt 23 inserted through the flange 20 to a nut portion 25 of the exhaust muffler 6.

The catalyst section is provided with a cylindrical catalyst section 17 only at the rear end of the joint pipe 5. However, as shown by a virtual line in FIG. 4, an existing metal honeycomb type catalyst in the exhaust muffler 6 is provided. The section 18 can be left as it is, and the rear end catalyst section 17 of the joint pipe 5 can be used as a preheating catalyst section.

In the case where the exhaust gas is used for preheating, a part of the exhaust gas is purified when the exhaust gas passes through the cylindrical catalyst portion 17.
Further, the exhaust gas temperature is raised by the reaction heat of the catalyst, and is sent into the exhaust muffler 6.

The exhaust gas whose temperature has risen contacts the main catalyst section 18 in the exhaust muffler 6, thereby promoting the activation of the main catalyst section 18 and improving the purification function.

[0020]

[Other embodiments]

(1) As the catalyst portion provided at the rear end of the joint pipe 5, for example, a cylindrical wire mesh or a perfectly circular cylindrical catalyst portion may be provided.

[0021]

【The invention's effect】

(1) As described above, according to the first aspect of the present invention, since the catalyst portion 8 is provided at the rear end of the joint pipe 5 separate from the exhaust muffler 6, the catalyst is directly provided only to the exhaust muffler 6. As compared with the structure in which the section is provided, the reaction heat of the catalyst section has less influence on the exhaust muffler 6, and the heat damage and discoloration of the exhaust muffler 6 can be reduced.

(2) At the rear end of the joint pipe 5, a catalyst portion 8
When the joint pipe 5 is detachably attached to the exhaust muffler 6, the inspection and replacement of the catalyst unit 8 can be easily performed by removing the joint pipe 5 from the exhaust muffler 6. Further, there is no need to replace the entire exhaust muffler 6 together with the catalyst section 8.

(3) The catalyst section 8 is provided at the rear end of the joint pipe without installing the catalyst section directly on the exhaust muffler 6, and the catalyst section 8 is inserted into the exhaust muffler 6 at the time of assembling. As described in the above effect (1), it is possible to prevent heat damage, but it is not necessary to provide a special member for guarding the catalyst portion 8. Also, the exhaust muffler 6 protects against external obstacles.

(4) Since the joint pipe 5 is a separate member from the exhaust muffler 6 and is detachably attached to the exhaust muffler 6, if the exhaust muffler 6 is deteriorated, only the exhaust muffler 6 can be easily replaced. It can be exchanged and is economical.

[Brief description of the drawings]

FIG. 1 is a side view of an exhaust device of a multi-cylinder motorcycle engine to which the present invention is applied.

FIG. 2 is an enlarged vertical sectional view of an arrow II portion in FIG.

FIG. 3 is an enlarged vertical sectional view of the same portion as that of FIG. 2 when disassembled.

FIG. 4 is an enlarged vertical sectional view showing a reference example.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a longitudinal sectional view of a conventional exhaust device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Exhaust pipe 3 Collecting pipe 5 Joint pipe 6 Exhaust muffler 8 Catalyst part 17 Catalyst part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-208146 (JP, A) JP-A-8-246861 (JP, A) JP-A-7-269331 (JP, A) JP-A-2- 61312 (JP, A) Japanese Utility Model Showa 54-148732 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 3/24 F01N 3/28

Claims (3)

(57) [Claims] An exhaust system in which a plurality of exhaust pipes extending from respective exhaust ports of an engine are assembled to an exhaust muffler via a collecting pipe and a joint pipe, and is formed of a member different from the exhaust muffler. And collecting pipe 3
And a joint pipe 5 forming an exhaust passage between the exhaust pipe and the exhaust muffler 6. A cylindrical portion 13 a having a diameter larger than the inner diameter of the joint pipe 5 is provided at an exhaust downstream end of the joint pipe 5. The catalyst portion 8 is fitted in the cylindrical portion 13a, and an outward flange 20 is provided in a portion of the joint pipe 5 upstream of the cylindrical portion 13a on the exhaust side, and the end portion of the exhaust muffler 6 on the exhaust inlet side has the cylindrical portion. 13a
A cylindrical portion 13a containing the catalyst portion 8 is inserted into the exhaust muffler 6 through the opening 22 and a flange 2 is formed.
0 is in contact with the end wall of the exhaust muffler 6 on the inlet side.
A catalyst device for an exhaust device, wherein the exhaust device and the exhaust muffler inlet side end wall are detachably connected to each other. 2. A catalyst device for an exhaust system according to claim 1, wherein a tapered portion 13 whose diameter increases toward the exhaust downstream side is provided at an end of the joint pipe 5 on the exhaust downstream side,
The catalyst portion 8 is fitted into a large-diameter cylindrical portion 13a formed at the end of the tapered portion 13 on the exhaust downstream side, and an outward flange 20 is attached to a portion of the joint pipe 5 upstream of the tapered portion 13. A catalyst device for an exhaust device, comprising: 3. The catalyst device for an exhaust device according to claim 1, wherein the catalyst unit 8 is of a metal honeycomb type.