Title of Invention

"A CATALYST CONTAINING EXHAUST SYSTEM FOR AN INTERNAL COMBUSTION ENGINE"

Abstract [Problem] In a catalyst-containing exhaust system for an internal combustion engine provided with a pipe-shaped metallic catalyst inside an exhaust pipe and having the metallic catalyst supported in the exhaust pipe via a buffer body, to enable reduced exhaust gas resistance and improved efficiency of reactive purification of exhaust gas by smoothing the flow of exhaust gas without being obstructed by the buffer body. [Means Of Solution] A catalyst holder Hc having a buffer body 6 is provided in an exhaust pipe P, a pipe-shaped metallic catalyst C is slidably supported via a stay 10 in the buffer body 6 so as to be separated from the buffer body 6, and an exhaust gas flow passageway 11 is formed between the catalyst C and the buffer body 6.
Full Text [Detailed Description Of The Invention]
[Technical Field Of The Invention]
The present invention relates to an exhaust system for an internal combustion engine, particularly for an internal combustion engine used to drive a two or three wheeled vehicle.
[Related Art]
A conventional catalyst-containing exhaust system having a pipe-
shaped catalyst located inside the exhaust system of an internal combustion engine in a motorcycle, and reactively purifying exhaust gas from this engine, is disclosed in Japanese Patent Laid-open No. Hei. 9-53441.
[Problems To Be Solved By The Invention]
However, in the conventional catalyst-containing exhaust system, a pipe-shaped catalyst arranged inside the exhaust pipe is supported in a tightly packed state by a buffer body comprised of glass wool or the like provided so as to run along the inner surface of the exhaust pipe, which means that the flow of exhaust gas between the exhaust pipe and the pipe-shaped catalyst is obstructed by the buffer body. This increases the resistance to the flow of exhaust gas somewhat, and as a result the contact surface area of the exhaust gas and the catalyst is reduced and the efficiency of reactively purifying the exhaust gas is lowered.
The present invention has been conceived in view of the above situation, and has as its object to provide a catalyst-containing exhaust system in a novel internal combustion engine that makes it possible to reduce resistance that a catalyst provides against the flow of exhaust gas as much as possible while slidably supporting a pipe-shaped catalyst in an exhaust pipe via a buffer body.
[Means Of Solving The Problems]
In order to achieve the above described object, according to the present invention there is provided a catalyst-containing exhaust system for an internal combustion engine provided with a pipe-shaped catalyst inside an exhaust pipe connected to an exhaust port of the internal combustion engine, the catalyst being supported by a buffer body provided in the exhaust pipe, wherein a catalyst holder having a buffer body is provided in the exhaust pipe, the catalyst is slidably supported by the buffer body through a stay so as to be separated from the buffer body, and an exhaust
gas flow path is formed between the catalyst and the buffer body. With this arrangement, exhaust gas flowing inside the exhaust pipe is not hindered by the buffer body while the pipe-shaped catalyst is slidably supported in the exhaust pipe and it is possible to improve output of the internal combustion engine by having smooth flow, and to improve the efficiency of reactively purifying exhaust gas using a catalyst.
Therefore, the present invention relates to ar\ catalyst. exhaust system for an internal combustion engine an exhaust pipe
connected to an exhaust port of an internal combustion engine
wherein a pipe shaped catalyst is placed wride the said oxhaust
pipe,the catalyst being supported by a buffer body provided in
the exhaust pipe, characteriged in that
a catalyst holder having the buffer body is provided in the exhaust pipe, the catalyst is slidably supported by the buffer body through a stay so as to be separated from the buffer body, and an exhaust gas flow path is formed between the catalyst and the buffer body.
[Brief Description Of The A
Fig. 1 is a side view of a motorcycle provided with the system of the
present invention.
Fig. 2 is a longitudinal sectional drawing of a catalyst section of an
exhaust system.
Fig. 3 is an enlarged cross sectional drawing along line 3 -3 in Fig. 2.
Fig. 4 is an enlarged cross sectional drawing along line 4 - 4 in Fig. 2.
Fig. 5 is an enlarged cross sectional drawing along line 5 - 5 in Fig. 2.
Fig. 6 is a cross sectional drawing along line 6 - 6 in Fig. 5.
Fig. 7 is a longitudinal sectional drawing of a silencer of an exhaust system.
Fig. 8 is a cross sectional drawing along line 8 - 8 in Fig. 7.
Fig. 9 is a cross sectional drawing along line 9 - 9 in Fig. 7.
Fig. 10 is a cross sectional drawing along line 10 - 10 in Fig. 7.
Fig. 11 is a side section of catalyst holding section of the exhaust system.
Fig. 12 is a cross sectional drawing along line 12- 10 in Fig. 11.
[Embodiments Of The Invention]
The present invention will now be described below based on embodiments shown in the attached drawings In the following description, terms such as front and rear, left and right, and up and down are with respect to the direction of travel of a motor cycle.
First of all, referring to Fig. 1 - Fig. 10, in a description of a first embodiment where the device of the present invention is applied to a motor cycle, Fig. l is a side view of a motorcycle provided with the system of the present invention, Fig. 2 is a longitudinal sectional drawing of a catalyst section of an exhaust system, Fig. 3 is an enlarged cross sectional drawing along line 3 -3 in Fig. 2, Fig. 4 is an enlarged cross sectional drawing along line 4 - 4 in Fig. 2, Fig. 5 is an enlarged cross sectional drawing along line 5 - 5 in Fig. 2, Fig. 6 is a cross sectional drawing along line 6 - 6 in Fig. 5, Fig. 7 is a longitudinal sectional drawing of a silencer of an exhaust system, Fig. 8 is a cross sectional drawing along line 8 - 8 in Fig. 7, Fig. 9 is a cross sectional drawing along line 9 - 9 in Fig. 7, and Fig. 10 is a cross sectional drawing along line 10 - 10 in Fig. 7.
In Fig. 1, an internal combustion engine E for powering a motorcycle is housed in a frame F of the motorcycle. An exhaust port Pe opens into a head portion front surface of the internal combustion engine E, and an exhaust system EX is communicatively connected to this exhaust port Pe. If the internal combustion engine E has multiple cylinders, the exhaust system EX is communicatively connected to the exhaust port via an exhaust manifold.
The exhaust system EX extends from the front of the internal combustion engine E along one side of the internal combustion engine E to the rear of the vehicle frame F. A rear end of the exhaust system EX runs along the side of a rear wheel Wr of the motor cycle and the outlet of the exhaust system EX faces to the rear and is open to the atmosphere. A hanger Ha is welded to a silencer M, to be described later, forming the rear part of the exhaust system EX, and a rear part of the exhaust system EX, namely the silencer M, is removably suspended from the vehicle frame F using attachment means such as nuts and bolts, etc., through this hanger Ha.
Next, the structure of the exhaust system EX will be described in detail with reference mainly to Fig. 2 - Fig. 10. This exhaust system EX is constructed having a silencer M integrally connected to a rear part of an exhaust pipe P communicatively connected to an exhaust port Pe of the internal combustion engine E.

A pipe-shaped metallic catalyst C, which will be described in detail later, is housed in the exhaust pipe P, and exhaust gas discharged from the internal combustion engine E has harmful components such as HC, CO, NOx etc. reactively purified by the metallic catalyst as the gas passes through the exhaust pipe P, passes through the silencer M and is discharged
to the atmosphere.
The exhaust pipe P is comprised of an upstream exhaust pipe 1, and a downstream exhaust pipe 2 connected to the lower end of the upstream exhaust pipe 1. The upstream exhaust pipe 1 is formed curving downwardly in a concave shape, a connecting flange is fixed to an upstream end of the upstream exhaust pipe 1 and this connecting flange 1, is attached to a mounting eye of the exhaust port Pe opening into the front surface of the internal combustion engine E by attachment means 3 such as bolts. A downstream end of the upstream exhaust pipe 1 is introduced into an upstream end of the downstream exhaust pipe 2 and connected together by welding. The downstream exhaust pipe 2 is formed by connecting together a rear end of a short upstream section 2u and a downstream section 2d being longer than the downstream section, by welding etc.
The downstream section 2d of the downstream exhaust pipe 2 is formed straight, and the pipe-shaped metallic catalyst C similarly formed straight is housed inside the downstream section 2d. The pipe-shaped metallic catalyst C is constructed with a catalyst element held on inner and outer surfaces of a catalyst body 9 formed as a pipe having both ends open from and made of a punched heat resistant metal plate such as a SUS plate
that has a plurality of small holes 9,. As shown in Fig. 2 and Fig. 3, a front part of the pipe-shaped metallic catalyst C is supported in a fixed state on the downstream exhaust pipe 2 through the front stay 4. The front stay 4 is formed as a hollow pipe having an oval cross section, and an inner circumferential surface of a small diameter section 4, of the stay 4 is attached to the outer circumferential surface of the metallic catalyst C by welding while the outer circumferential surface of a large diameter section 42 is connected to the inner circumferential surface of a front part of the downstream exhaust pipe 2 by welding. Accordingly, the front part of the pipe-shaped metallic catalyst C is fixedly supported on a front part of the downstream exhaust pipe 2 via the stay 4, and an annular exhaust gas passageway is formed between this downstream exhaust pipe 2 and the metallic catalyst C. [0017]-
As shown in Fig. 2, Fig. 5 and Fig. 6, a rear part of the metallic catalyst C is supported on the downstream exhaust pipe 2 via a catalyst holder Hc so as to be slidable in the longitudinal direction of the downstream exhaust pipe 2. The catalyst holder Hc is interposed along a downstream section 2d of the downstream exhaust pipe 2, a buffer body 6 is loaded inside an annular cavity of a short cylindrical holder case 5 formed having a larger diameter than the downstream section 2d, and an annular support pipe 7 having substantially the same diameter as the downstream section 2d of the downstream exhaust pipe 2 is provided along the inner circumferential surface of the buffer body 6. The holder case 5 is fixed by welding or the like between longitudinally separated front and rear sections of the downstream section 2d of the downstream exhaust pipe 2,
and the support pipe 7 has a plurality of vents 8 drilled in its wall causing exhaust gas to flow through the vents 8 into the buffer body 6 so that it is possible for the buffer body 6 to absorb and reduce the noise of the exhaust gas. The buffer body 6 is formed as a mesh of SUS wool. As clearly shown in Fig. 5 and Fig. 6, an inner circumference surface of a small diameter section 10, of a rear stay 10 comprised of an annular cylinder having the same oval cross sectional shape as the front stay 4 is fixed by welding or the like to an outer circumference surface of a rear part of the metallic catalyst facing the catalyst holder Hc, and an outer circumferential surface of a large diameter section 102 of the rear stay 10 is supported on an inner circumferential surface of the support pipe 7 of the catalyst holder Hc so as to be slidable in the axial direction. Accordingly, the rear part of the pipe-shaped metallic catalyst C is slidable in a longitudinal direction with respect to the downstream exhaust pipe 2 using the catalyst holder Hc and is permitted to pinch and swell_relative to the downstream exhaust pipe 2 due to heating etc. of the metallic catalyst C. Also, the metallic catalyst C is supported in the downstream exhaust pipe 2 via the buffer body 6 so as to be buffered and a separated exhaust gas flow passageway 11 is formed between the outer circumferential surface of the metallic catalyst C and the buffer body 6 of the catalyst holder Hc so as to keep them apart. In this way, exhaust gas flowing through the metallic catalyst C is not obstructed by the buffer body 6 and flows through the flow passageway 11 with reduced resistance. As shown clearly in Fig 2 and Fig. 4, a large part of the downstream exhaust pipe 2 is insulated by a heat insulation pipe 12. This heat insulation
pipe 12 is formed having a rear heat insulation pipe 122 integrally connected to a rear end of a front heat insulation pipe 12, by welding etc., and the front end of the rear heat insulation pipe 12, is fixed to an upstream end of the downstream exhaust pipe 2 by welding. Also, squashed sections 13 having a U-shaped cross section and forming a pair substantially 180° apart are formed in the rear end of the heat insulation pipe 12, with inner surfaces of these squashed sections 13 being tightly pressed against the outer circumferential surface of the rear end of the downstream exhaust pipe 2 and a rear end of the heat insulation pipe 12 being supported by the downstream exhaust pipe 2.
The heat insulation pipe 12 is useful for reducing heat damage on the outer pipe 18 of the silencer M, that will be described later, by limiting diffusion of heat from the exhaust pipe P to the outer surface accompanying heat retention of the metallic catalyst and for increasing reactive purification efficiency of the metallic catalyst.
As shown in Fig. 2, a short hollow pipe-shaped color change prevention pipe 15 is fixed to the upstream section 2u of the downstream exhaust pipe 2 by welding etc. This color change prevention pipe 15 is interposed between the downstream exhaust pipe 2 and the heat insulation pipe 12, and respective gaps are formed between them. An exhaust gas detour path 16 composed of a plurality of small holes separated in the circumferential direction is formed in a portion covered by the color change prevention pipe 15 of the downstream exhaust pipe 2. Some of the exhaust gas flowing from the internal combustion engine E through the upstream exhaust pipe 1 to the downstream exhaust pipe 2 flows so as to detour in a
backward direction through the exhaust gas detour path 16 and between the downstream exhaust pipe 2 and the heat insulation pipe 12, and in this way resistance to the exhaust gas is reduced increasing the output of the internal combustion engine E, and particularly it becomes possible to contribute to increasing the output of the engine in a low speed operating region.
The downstream exhaust pipe 2 and the heat insulation pipe 12 are introduced into the silencer M constituting the rear half of the exhaust system EX from an inlet side thereof, an inlet end of the silencer M is fixed to the outer circumference of a front end of the front heat insulation pipe 12, by welding or the like, and the downstream section 2d of the downstream exhaust pipe 2 extends to a mid-point of the silencer M.
As shown in Fig. 7 and Fig. 8, an outer tube 18 of the silencer M is comprised of a truncated cone-like front outer pipe 18f spreading out like an open fan to the rear and a cylindrical rear outer pipe 18r fixed to the rear end of the front outer pipe 18f by welding or the like. An inner pipe 19 defining an annular aperture is provided inside the rear outer pipe 18r. The inside of the inner pipe 19 is divided up into a first chamber 23, a second chamber 24 and a third chamber 25 by a first partition 20, a second partition 21 and a rear wall 19, of the inner pipe 19. The first chamber 23 and the third chamber 25 are connected together by a first connecting pipe 26 linking between the first partition 20 and the second partition 21. The third chamber 25 and the second chamber 24 are connected by a second connecting pipe 27 being cantilever supported in the second partition 21, and the second chamber 24 is connected to the outside atmosphere by a third connecting pipe 28 linking between the second partition 21 and a rear
wall 18, of the outer pipe 18. Exhaust gas that has passed from the downstream exhaust pipe 2 through the metallic catalyst and has been reactively purified flows into the inside of the silencer M, here flowing from the first chamber 23 through the first connecting pipe 26 and into the third chamber 25, then from this third chamber 25 through the second connecting pipe 27 into the second chamber 24, and finally from the second chamber 24 through the third connecting pipe 28 to be discharged into the atmosphere. While this is going on, the exhaust gas repeatedly expands and contracts inside the silencer M, and noise of the flowing gas is effectively reduced and discharged to the atmosphere due to detouring around the first, third and second chambers 23, 25 and 24 of the silencer M.
Next, the operation of the first embodiment will be described. Exhaust gas that has been generated by operation of the internal combustion engine E flows from the exhaust port Pe through the upstream exhaust pipe 1 to the downstream exhaust pipe 2. Exhaust gas that has had harmful components included therein reactively removed by the pipe-shaped metallic catalyst C provided in the downstream exhaust pipe 2 flows to the silencer M where noise is reduced before being discharged to the atmosphere.
Since the flow passageway 11 for the exhaust gas is formed between the metallic catalyst C and the holder body 6 of the catalyst holder Hc for supporting the catalyst in a buffered manner, thus keeping them apart, exhaust gas flowing at the outer side of the metallic catalyst is not
obstructed by the buffer body 6 and flows smoothly without disturbance arising in the flow, and in this way it is possible not only to improve output of the internal combustion engine E by reducing resistance to the exhaust gas, but also to increase the efficiency of purifying exhaust gas using the catalyst C by increasing the contact surface area of the exhaust gas with the metallic catalyst C.
A second embodiment of the present invention will now be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a side section of catalyst holding section of the exhaust system and Fig. 12 is a cross sectional drawing along line 12 - 10 in Fig. 11. Parts that are the same as those in the first embodiment have the same reference numerals attached thereto.
In this second embodiment, the structure of the catalyst holder Hc is different from that of the first embodiment. This catalyst holder Hc is comprised of a holder case 5 and a buffer body 6 loaded inside the holder case 5. An inner surface of this buffer body 6 is in direct contact with an outer circumferential surface of a rear stay 10 having an oval cross section and fixed to the metallic catalyst, inside the downstream exhaust pipe 2, and is supported so as to be slidable in an axial direction. It can therefore be seen that the second embodiment does away with the support pipe of the first embodiment.
The exhaust system of the second embodiment also has the rear part of the pipe-shaped metallic catalyst C supported so as to be slidable in the
axial direction by the buffer body 6 of the catalyst holder He, and the metallic catalyst C is separated from the buffer body 6 and an exhaust gas flow passageway 11 can be formed between them. The second embodiment can achieve the same effects as the first embodiment, and further, because there is no longer any need for the support pipe (as in the first embodiment) the number of components is reduced and it is possible to educe the cost of the exhaust system.
Description has been given above for embodiments of the present invention, but the present invention is not limited to these embodiments and various modifications are possible within the scope of the appended claims. For example, in the embodiments above, description has been given for the case where the exhaust system of the present invention is adopted as the exhaust system for an internal combustion engine of a motorcycle but it can also be used as an exhaust system for other vehicles and for other machines. Also, description has been given for the case where a pipe-shaped catalyst is used as the metallic catalyst C, but it is also possible to use other catalysts such as a non-metallic catalyst. Further, SUS wool has been used as the buffer body in the embodiments above, but it is also possible to use any other conventionally known buffer body.
[Effects Of The Invention]
According to the present invention as described in the above, in a catalyst-containing exhaust system, a catalyst holder having a buffer body is provided in an exhaust pipe, and a catalyst is slidably supported in the buffer body through a stay so as to be separated from the buffer body. Since an exhaust gas flow passageway is formed between the catalyst and



WE CLAIM:
1. A catalyst containing exhaust system for an internal combustion
engine provided with a pipe-shaped catalyst (C) inside an exhaust
pipe (P) connected to an exhaust port (Pe) of an internal combustion
engine (E), the catalyst (C) being supported by a buffer body (6)
provided in the exhaust pipe (P), wherein
a catalyst holder (Hc) having the buffer body (6) is provided in the exhaust pipe (P), the catalyst (C) is slidably supported by the buffer body (6) through a stay (10) so as to be separated from the buffer body (6), and an exhaust gas flow path (11) is formed between the catalyst (C) and the buffer body (6).
2. A catalyst containing exhaust system for an internal combustion
engine substantially as herein described with reference to the
accompanying drawings.

Documents:

3809-del-1998-abstract.pdf

3809-del-1998-claims.pdf

3809-del-1998-correspondence-others.pdf

3809-del-1998-correspondence-po.pdf

3809-del-1998-description (complete).pdf

3809-del-1998-drawings.pdf

3809-del-1998-form-1.pdf

3809-del-1998-form-13.pdf

3809-del-1998-form-19.pdf

3809-del-1998-form-2.pdf

3809-del-1998-form-3.pdf

3809-del-1998-form-4.pdf

3809-del-1998-form-6.pdf

3809-del-1998-gpa.pdf

3809-del-1998-petition-137.pdf

3809-del-1998-petition-138.pdf

abstract.jpg


Patent Number 215055
Indian Patent Application Number 3809/DEL/1998
PG Journal Number 10/2008
Publication Date 07-Mar-2008
Grant Date 21-Feb-2008
Date of Filing 22-Dec-1998
Name of Patentee HONDA GIKEN KOGYO KABUSHIKI KAISHA
Applicant Address 1-1, MINAMIAOYAMA 2-CHOME, MINATO-KU, TOKYO, JAPAN
Inventors:
# Inventor's Name Inventor's Address
1 TOSHIHIRO OOTAKA C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, OF 4-1, CHUO 1-CHOME,WAKO-SHI, SAITAMA, JAPAN
PCT International Classification Number B01J 8/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 HEI-10-022458 1998-02-04 Japan