JP2000265829A - Exhaust gas purification device - Google Patents

Abstract

(57) [Problem] To provide a sufficient exhaust gas purification effect while minimizing an increase in exhaust gas flow resistance due to a catalytic converter. SOLUTION: Downstream ends of four exhaust pipes 16 extending from a multi-cylinder engine are gathered and connected to an upstream end of an exhaust expansion section 17, and a downstream end of the exhaust expansion section 17 is connected to one exhaust manifold 18. Connect to the upstream end. One end of the pair of mounting stays 30 is fixed to the inner peripheral surface of the exhaust expansion section 17, and the outer peripheral surface of the catalytic converter 26 is supported at the other end. Catalytic converter 26
Is obtained by supporting a catalyst on a carrier like a pipe that has been punched holes 26 ₁ formed, its axis L is arranged along the flow direction of the exhaust gas. With this configuration, a smooth flow of the exhaust gas is enabled, and the flow resistance of the exhaust gas can be effectively reduced.
Exhaust gas can be effectively brought into contact with 6 to enhance the purification effect. ,

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms an exhaust expansion section having an increased exhaust gas passage sectional area downstream of a plurality of exhaust pipes extending from a multi-cylinder engine, and purifies the exhaust gas in the exhaust expansion section. The present invention relates to an exhaust gas purification device provided with a catalytic converter.

[0002]

2. Description of the Related Art An exhaust gas purifying apparatus is known in which a plurality of exhaust pipes extending from a multi-cylinder engine of a motorcycle are bundled by an exhaust collecting pipe, and a catalytic converter is arranged inside a muffler connected to the exhaust collecting pipe via a joint pipe. JP-A-10-1
No. 03046. In this way, by arranging the catalytic converter inside the muffler, which is an exhaust expansion section in which the cross-sectional area of the exhaust gas increases, the increase in the flow resistance of the exhaust gas caused by the catalytic converter is suppressed to avoid a decrease in engine output. can do.

[0003]

However, in the above prior art, the catalytic converter is composed of a honeycomb plate in which a plate carrying a catalyst is spirally wound, and the catalytic converter is configured to flow exhaust gas flowing through a muffler. Since it is arranged so as to completely block the road, there is a problem that it is difficult to suppress the increase in the exhaust gas flow resistance sufficiently low.

The present invention has been made in view of the above circumstances, and has an exhaust gas purifying apparatus capable of exhibiting a sufficient exhaust gas purifying effect while minimizing an increase in exhaust gas flow resistance caused by a catalytic converter. The purpose is to provide.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, the cross-sectional area of the exhaust gas passage increases downstream of a plurality of exhaust pipes extending from a multi-cylinder engine. An exhaust gas purification device in which an exhaust expansion section is formed, and a catalytic converter for purifying exhaust gas is disposed in the exhaust expansion section, wherein the catalytic converter is formed in a pipe shape through which exhaust gas can pass inside and outside, and There is proposed an exhaust gas purifying apparatus characterized in that the exhaust gas purifying apparatus is arranged along an axis in a flowing direction of the exhaust gas.

According to the above configuration, the catalytic converter is disposed in the exhaust expansion section formed on the downstream side of the plurality of exhaust pipes and having an increased cross-sectional area of the exhaust gas. The increase can be minimized. Moreover, the catalytic converter is formed into a pipe shape through which the exhaust gas can pass inside and outside, and is arranged along the axis in the direction in which the exhaust gas flows, enabling a smooth flow of the exhaust gas and reducing the flow resistance of the exhaust gas. Not only can it be reduced more effectively, but also the exhaust gas can be brought into effective contact with the catalytic converter to increase the purification efficiency.

According to the second aspect of the present invention,
In addition to the configuration of claim 1, one end of the mounting stay is fixed near the upstream end of the exhaust expansion section to which the plurality of exhaust pipes are connected, and the other end of the mounting stay supports the catalytic converter. An exhaust gas purification device is proposed.

According to the above construction, the mounting stay supporting the catalytic converter is fixed near the upstream end of the exhaust expansion portion whose rigidity is increased by connecting a plurality of exhaust pipes. Can be increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 5 show a first embodiment of the present invention. FIG. 1 is an overall side view of a motorcycle provided with an exhaust gas purifying device, FIG. 2 is an enlarged sectional view of a part of FIG. 3 is a sectional view taken along line 3-3 of FIG. 2, FIG. 4 is a sectional view taken along line 4-4 of FIG. 2, and FIG. 5 is a sectional view taken along line 5-5 of FIG.

As shown in FIG. 1, the motorcycle V has a front wheel Wf pivotally supported by a lower end of a front fork 12 connected to a steering handle 11 and a rear pivotally supported by a rear cushion 13 so as to be vertically swingable. A rear wheel Wr is supported at the rear end of the fork 14. The rear wheel Wr is driven via a chain 15 by a power unit P mounted on the center of the vehicle body. The power unit P includes a four-cylinder engine E and a transmission T integrally.
Four exhaust pipes 16 extend forward and downward from the lower surface of the cylinder head of the engine E whose cylinder axis is inclined forward and upward. The four exhaust pipes 16 bend rearward and gather at the exhaust expansion section 17 below the transmission T. In the exhaust expansion section 17, the exhaust collecting pipes 18 that are gathered together rise up and then bend upward and rearward, and are connected to a muffler 19 disposed on the rear right side of the vehicle body.

As shown in FIG. 2 to FIG.
Of the four exhaust pipes 16 bundled together at the upstream position of
The outer casings are arranged coaxially through the collar 21.
Double pipe structure composed of IP22 and inner pipe 23
And a space 24 is formed between the pipes 22 and 23.
Thus, the temperature of the exhaust gas is prevented from lowering. 90 °
The space formed between the four exhaust pipes 16 bundled at a distance
In the meantime, weld them W _ThreeBy the closing plate 25 fixed at
Closed.

The exhaust expansion section 17 is a cylindrical member whose outer diameter decreases from the upstream side to the downstream side, and has an irregular cross section in which four semicircles are arranged at 90 ° intervals in the circumferential direction. From the upstream end connected to the four exhaust pipes 16 by welding W ₁ toward the downstream end connected to one exhaust collecting pipe 18 having a circular cross section, the cross-sectional shape of which is smooth. Is changing. The catalyst converter 26 disposed inside the exhaust expansion section 17 is formed by carrying a catalyst such as platinum or rhodium on the entire surface of a pipe-shaped catalyst carrier in which a number of punching holes 26 ₁ are formed. The axis L of the catalytic converter 26 is disposed along the flow direction of the exhaust gas inside the exhaust expansion section 17, and its upstream end reaches near the downstream ends of the four exhaust pipes 16. The downstream end is an exhaust manifold 1 connected to the exhaust expansion section 17 by welding W _2.
8 protrudes by a distance A.

The cross-sectional area of the exhaust gas passage in the exhaust expansion section 17 is larger than the sum of the cross-sectional areas of the four exhaust pipes 16 and larger than the cross-sectional area of one exhaust manifold 18. I have. Therefore, the flow rate of the exhaust gas flowing through the exhaust expansion section 17 is the same as the exhaust pipe 16.
Is smaller than the flow velocity of the exhaust gas flowing through.

The outer peripheral surface of the catalytic converter 26 is slidably supported by fitting to two cylindrical inner holders 27, 27, and is formed to have a semicircular cross-section outside in the radial direction. It is fixed by the two outer holders 28 and 28 are fitted in weld W ₄ that is, steel wool 29 is filled further between the inner holder 27 and outer holder 28, 28. The inner peripheral surface of the upstream end near the exhaust expansion portion 17, i.e., four exhaust pipes 16 ... a pair of mounting stays 30, 30 at a position adjacent to the downstream end of which is fixed by welding W _5.

The cross section of the upstream end of each mounting stay 30 has a shape in which two arcs are connected so as to follow the inner surface shape of the exhaust expansion section 17, and the downstream section whose cross section changes to a semicircular shape therefrom. side portion, is fixed by welding W ₆ on the outer peripheral surface of the outer holder 28, outer holder 28
And it is secured by welding W ₇ in the inner holder 27. And two through holes 3 are provided in the middle of the mounting stay 30.
0 ₁ and 30 ₁ are formed.

Next, the operation of the embodiment of the present invention having the above configuration will be described.

Exhaust gas discharged from the cylinder head of the multi-cylinder engine E to the four exhaust pipes 16 flows into the upstream end of the exhaust expansion section 17 from the downstream ends of the exhaust pipes 16 bundled together. . Part of the exhaust gas that has flowed into the exhaust expansion section 17 flows inside the pipe-shaped catalytic converter 26, and another part is the space between the two mounting stays 30, 30 or the space between the mounting stays 30, 30. After passing through the through-holes 30 ₁ ... And flowing outside the catalytic converter 26, the exhaust gas flows from the inside and outside of the catalytic converter 26 into a large number of punching holes 2.
While passing through 6 and moving to the other side inside and outside,
The catalyst is purified by contacting the catalyst carried on the surface of the catalytic converter 26. Then, the purified exhaust gas is supplied to the exhaust manifold 1
The gas is discharged to the atmosphere via the muffler 8 and the muffler 19.

As described above, the catalytic converter 26 is disposed in the exhaust expansion section 17 connected to the downstream side of the four exhaust pipes 16 and having an increased passage cross-sectional area, and the catalytic converter 26 is formed in a pipe shape. As a result, the arrangement is made so as to be along the direction in which the exhaust gas flows, so that an increase in the flow resistance of the exhaust gas caused by the catalytic converter 26 can be suppressed to a low level, and a decrease in the engine output can be prevented. Catalytic converter 2
6 has a large number of punching holes 26 _1, so that the area for carrying the catalyst is increased, and the catalytic converter 2 is provided with mounting stays 30, 30 which partially block the flow of exhaust gas.
Since the flow of the exhaust gas between one side and the other side of the inside and outside of 6 is promoted, the exhaust gas can be brought into effective contact with the catalyst to increase the purification efficiency. Further, since a part of the catalytic converter 26 extends inside the exhaust manifold 18, the exhaust gas can be smoothly guided from the exhaust expansion section 17 to the exhaust manifold 18 to reduce the flow resistance.

The vicinity of the upstream end of the exhaust expansion section 17 to which the mounting stays 30 are fixed is increased in rigidity by the connection of the four exhaust pipes 16.
The catalytic converter 26 by the mounting stays 30, 30 has high bending rigidity due to the curved cross-sectional shape itself.
Can be sufficiently increased in mounting rigidity.

Next, a second embodiment of the present invention will be described with reference to FIGS.

In the first embodiment described above, the catalytic converter 26 is connected to the exhaust expansion section 1 by the two mounting stays 30, 30.
7, but in the second embodiment, the catalytic converter 2
6 is supported by the exhaust expansion section 17 by one mounting stay 31. The mounting stay 31 is formed of a plate body having a corrugated cross section, and both ends of the mounting stay 31 are fixed to the inner wall surface of the exhaust expansion section 17 by welding W ₈ , and an intermediate portion thereof holds the catalytic converter 26. Are fixed to the outer holders 28 and 28 by welding W ₉ , so that the catalytic converter 26 is supported by the exhaust expansion portion 17.

According to this embodiment, the number of mounting stays 31 is one.
Not only the number of parts is reduced due to the need for individual components, but also the mounting stay 31 is arranged substantially parallel to the flow direction of the exhaust gas, which further reduces the flow resistance of the exhaust gas. Can be.

Although the embodiments of the present invention have been described in detail above, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, four exhaust pipes 16 are assembled in the exhaust expansion section 17, but the number of exhaust pipes 16 to be assembled is not limited to four.

[0026]

As described above, according to the first aspect of the present invention, the catalytic converter is disposed in the exhaust expansion section formed downstream of the plurality of exhaust pipes and having an increased exhaust gas passage cross-sectional area. Therefore, an increase in exhaust gas flow resistance due to the catalytic converter can be minimized. Moreover, the catalytic converter is formed into a pipe shape through which the exhaust gas can pass inside and outside, and is arranged along the axis in the direction in which the exhaust gas flows, enabling a smooth flow of the exhaust gas and reducing the flow resistance of the exhaust gas. Not only can it be reduced more effectively, but also the exhaust gas can be brought into effective contact with the catalytic converter to increase the purification efficiency.

According to the second aspect of the present invention,
Since the mounting stay that supports the catalytic converter is fixed near the upstream end of the exhaust expansion section whose rigidity is increased by connecting a plurality of exhaust pipes, the rigidity of the support of the catalytic converter by the mounting stay can be increased.

[Brief description of the drawings]

FIG. 1 is an overall side view of a motorcycle equipped with an exhaust gas purification device.

FIG. 2 is an enlarged sectional view of a part 2 of FIG.

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

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2;

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

FIG. 6 corresponds to FIG. 2 according to a second embodiment of the present invention.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6;

[Explanation of symbols]

 Reference Signs List 16 exhaust pipe 17 exhaust expansion section 26 catalytic converter 30 mounting stay E engine L axis

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F01N 7/08 F01N 7/10 7/10 B01D 53/36 ZABB F-term (Reference) 3G004 AA02 BA03 BA06 CA13 DA04 DA14 EA05 FA01 FA04 GA01 GA06 3G091 AA03 AA28 AB01 BA38 GA03 GA21 GB05W GB06W HA27 HA28 HA31 HB02 4D048 AA06 AA13 AA18 AB05 BA30X BA33X BB05 BB12 CA01 CC08 CC25

Claims (2)

[Claims] An exhaust expansion section (17) having an increased exhaust gas passage cross-sectional area is formed downstream of a plurality of exhaust pipes (16) extending from a multi-cylinder engine (E).
7) An exhaust gas purifying apparatus in which a catalytic converter (26) for purifying exhaust gas is disposed, wherein the catalytic converter (26) is formed in a pipe shape through which the exhaust gas can pass inside and outside, and in a direction in which the exhaust gas flows. An exhaust gas purifying apparatus characterized by being arranged along an axis (L). 2. An end of a mounting stay (30) is fixed near an upstream end of an exhaust expansion section (17) to which a plurality of exhaust pipes (16) are connected, and a catalytic converter is connected to the other end of the mounting stay (30). 2. The method according to claim 1, wherein said step (26) is supported.
An exhaust gas purifying apparatus according to claim 1.