JP3284909B2 - Engine exhaust system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine exhaust device configured to purify exhaust gas by providing a catalyst member therein.

[0002]

2. Description of the Related Art There is an exhaust device of an engine mounted on a motorcycle or the like, which is configured to purify exhaust gas by providing a catalyst member inside.
Many of such exhaust devices have a tubular main body, and a divergent tapered cylindrical diffuser is provided inside. Then, a catalyst member is provided inside the diffuser.

As shown in FIG. 4, a catalyst member 100 is generally formed in a cylindrical shape, and support brackets 101 and 102 or a baffle plate 1 are provided at both ends of the catalyst member 100.
Fixing tools such as 03, 104 are fixed, and these fixing tools 101, 102, 103, 104 are fixed to the inner surface of the diffuser. Thereby, the catalyst member 100 is coaxially fixed inside the diffuser.

[0004]

However, the catalyst member 100 is extremely hot due to the catalytic reaction caused by contact with the exhaust gas. At high temperatures, the catalyst member 100 expands to extend its entire length. When both ends of the fixing member 100 are fixed to the inner surface of the diffuser by the fixing members 101, 102, 103 and 104, the fixing members 101, 102, and 10 each time the catalyst member 100 expands and contracts.
There is a concern that stress is applied to 3,104 and its durability is deteriorated.

Also, fixtures 101, 102, 103, 1
Depending on the shape of 04, metal fatigue may occur while receiving stress caused by engine vibration for a long period of time, and there is a concern that durability may also deteriorate. Further, the fixing member is connected to the catalyst member 1.
There is also a problem that the number of parts increases because it is necessary to provide them around 00.

An exhaust system for an engine according to the present invention has been made in order to solve such a problem. The first object of the present invention is to prevent the catalyst member itself from being adversely affected by thermal expansion or engine vibration. Another object of the present invention is to make it possible to dispose the catalyst member inside the diffuser with a simple and simple structure.

A second object of the engine exhaust system according to the present invention is to maximize the performance of a catalyst member provided inside the diffuser to improve exhaust gas purification efficiency.

[0008]

In order to achieve the first object, an exhaust system for an engine according to the present invention comprises:
As described in above, an engine located at the forehead, and a unit case provided integrally with the engine and extending rearward, the rear wheel is directly supported at the rear end of the unit case, the unit case A scooter-type motorcycle in which a power unit that accommodates a transmission and a clutch mechanism for shifting the power of the engine and transmitting the power to the rear wheel inside the vehicle is swingably connected to a vehicle body frame in the up and down direction. An exhaust pipe connected to the engine, an exhaust device main body connected to the exhaust pipe, a diffuser disposed inside the exhaust device main body and having one end communicating with the exhaust pipe, and a tubular catalyst member. In the exhaust system for an engine provided with the diffuser, the diffuser is formed in a tapered cylindrical shape that expands in diameter at the end, and an opening on the downstream side protrudes into the exhaust device main body. In addition, the catalyst member is a tapered tube carrying a catalyst substance, and the catalyst member is disposed substantially concentrically within the diffuser so as not to protrude from the downstream opening of the diffuser. A substantially central portion in the direction is fixed to the inner wall of the diffuser by a support bracket to form an exhaust gas flow passage between the diffuser and the catalyst member, and the support bracket is formed into a substantially “M” shape in the axial direction of the catalyst member. And two supporting arms extending radially from the catalyst member and fixed to the inner surface of the diffuser, and the opening angle of these supporting arms is set in the range of 60 ° to 120 °. I do.

In order to achieve the second object, an exhaust system for an engine according to the present invention is provided with a catalyst means also in the diffuser itself, as described in claim 2.
This catalyst means was overlapped with a catalyst member provided in the diffuser in a side view.

When the exhaust device of the engine is constructed as in claim 1, only the longitudinal central portion of the catalyst member is fixed to the inner surface of the diffuser by the support bracket, so that the total length of the catalyst member changes due to thermal expansion. However, no stress is applied to the support bracket located at the intermediate portion of the catalyst member, so that the durability of the support bracket does not deteriorate.

Further, two support arms of the support bracket extend radially from the catalyst member and are fixed to the inner surface of the diffuser, and the two support arms have an opening angle of 60 ° to 120 °. Since it is set in the range, the catalyst member can be supported with the highest rigidity against stress caused by engine vibration. For this reason, even if the support bracket is exposed to engine vibration for a long period of time, metal fatigue of the support bracket does not easily occur, and in this respect, deterioration of the durability of the support bracket can be prevented. In addition, since the catalyst member is fixed in the diffuser by one support bracket, the structure for supporting the catalyst member is simplified.

Further, since the tapered catalyst member does not protrude from the downstream opening of the diffuser, the temperature rise of the catalyst member is accelerated by the diffuser, the temperature of the catalyst member is maintained at a high temperature, and the exhaust gas purification efficiency is improved. I do.

Further, according to the exhaust system of the engine, the catalyst means is provided also in the diffuser itself so as to overlap the catalyst member provided in the diffuser in a side view. The synergistic action with the catalyst means maximizes the performance of the catalyst member and greatly improves exhaust gas purification efficiency.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a left side view of a motorcycle provided with an exhaust device according to the present invention. The motorcycle 1 is a scooter type, and a power unit 3 is connected to a vehicle body frame 2 via a link 4 so as to be vertically swingable.
The power unit 3 includes an engine 5 located at the forehead.
And a unit case 6 provided integrally on the left side surface of the engine 5 and extending rearward. A rear wheel 7 is directly supported at the rearmost portion of the unit case 6, and inside the unit case 6. A transmission, a clutch mechanism, and the like for shifting the power of the engine 5 and transmitting the power to the rear wheels 7 are housed therein. In addition, 8 is a shock absorber.

The engine 5 has an exhaust system 10 according to the present invention.
Is connected. The overall configuration of the exhaust device 10 is such that a cylindrical exhaust device main body 12 having a large-diameter intermediate portion is connected to an exhaust pipe 11 having a constant thickness, which extends from an exhaust port (not shown) of the engine 5. The silencer 13 is connected to the section.

FIG. 2 is a cross-sectional view of the exhaust device 10 taken along the line II-II of FIG. A diffuser 14 is connected to a rear end of the exhaust pipe 11 shown in FIG. The diffuser 14 is formed in a tapered cylindrical shape that expands in diameter toward the end, and an opening 15 on the downstream side protrudes into the exhaust device main body 12, and the opening 15 is located near the maximum outer diameter portion of the exhaust device main body 12. It is located in.

The internal space of the exhaust device main body 12 is partitioned by a partition 16 into a first expansion chamber 17 on the front side and a second expansion chamber 18 on the rear side, and a downstream opening 1 of the diffuser 14 is formed.
5 opens into the first expansion chamber 17. Also, the partition 16
The first expansion chamber 17 and the second expansion chamber 18 communicate with each other through a communication pipe 19.

Further, the inner peripheral portion of the exhaust device main body 12 is partially formed into a double pipe structure by perforated plates 21 and 22 such as a punching plate. The catalyst components are sprayed onto the perforated plates 21 and 22 and the cloth catalysts 23 and 24 are adhered from the outside. The exhaust device body 12 and the perforated plates 21 and 22
A sound absorbing and heat insulating material 25, 26 such as glass wool is filled between them.

Further, the silencer 13 is formed in a can shape having a constant thickness, and is fixed to a rear portion of the exhaust device main body 12. The internal space of the silencer 13 communicates with the second expansion chamber 18 by an inlet pipe 28 provided so as to penetrate the front surface thereof. In addition, silencer 1
An outlet pipe 29 is provided so as to penetrate the rear surface of the outlet pipe 3.

The inside of the silencer 13 is also partially formed into a double-pipe structure by a perforated plate 30 such as a punching plate. A catalyst component is sprayed on the perforated plate 30 and a cloth-like catalyst 31 is adhered from the outside. The surroundings are filled with a sound absorbing heat insulating material 32 such as glass wool.

As shown in FIG. 3, a cylindrical catalyst member 34 is coaxially fixed inside the diffuser 14 via a support bracket 35. This catalyst member 3
Numeral 4 is, for example, a catalyst component sprayed on a metal tube. The diffuser 14 has an intermediate structure in which upper and lower (or left and right) semi-cylindrical halves 14a and 14b are welded and joined to each other.
Before joining b, the support bracket 35 of the catalyst member 34 is fixed to the inner surface of one half body (here, 14b).

The support bracket 35 is formed, for example, by pressing a band-shaped plate material into a substantially "M" shape.
A curved joining surface 35a to be joined to the catalyst member 34, two support arms 35b and 35c that bend and extend from both ends of the joining surface 35a, and these support arms 35b and 35c
There are provided bonding surfaces 35d and 35e for bonding the 35c to the inner surface of the diffuser 14.

When the joining surface 35a is joined to the catalyst member 34, the two support arms 35b and 35c
And the opening angle A is 6
It is molded so that it is set in the range of 0 ° to 120 °, preferably 90 °. Further, the joining surface 35a is fixed to the center of the catalyst member 34 in the longitudinal direction.

The catalyst member 3 in the diffuser 14
The fixing position of 4 is set such that the rear end of the catalyst member 34 does not protrude from the downstream opening 15 of the diffuser 14. In this embodiment, the rear end of the catalyst member 34 is located about several centimeters upstream from the downstream opening 15 of the diffuser 14.

On the other hand, the diffuser 14 itself is also provided with a catalyst means. In the present embodiment, a part of the section B of the diffuser 14 is formed in a porous shape, and a cloth-like catalyst 37 is attached to the outer periphery of the section B as a catalyst means.
An outer cylinder 38 having a slightly larger diameter is wound so as to cover the section B, and a sound absorbing and heat insulating material 39 such as glass wool is filled between the outer cylinder 38 and the diffuser 14. The position of the cloth catalyst 37 is determined by the position of the catalyst member 34 fixed in the diffuser 14.
Need to be set so that they overlap in side view.

In the exhaust system 10 configured as described above, the exhaust gas discharged from the engine 5 is supplied to the exhaust pipe 1.
1 and the diffuser 14 are led to the first expansion chamber 17 of the exhaust device main body 12, then to the second expansion chamber 18 through the communication pipe 19, and further guided to the silencer 13 via the inlet pipe 28. Finally, it is discharged to the outside through the outlet pipe 29.

The exhaust gas is effectively silenced by the expansion action in the two expansion chambers 17 and 18 and the silencer 13 and the sound absorption action of the sound absorbing and insulating materials 25, 26, 32 and 39 arranged in each part. At the same time, the exhaust gas is supplied to the cylindrical catalyst member 34 provided in the diffuser 14, the cloth-like catalyst 37 provided as a catalyst means provided in the diffuser 14 itself, and the catalyst sprayed on each of the porous plates 21, 22, 30. By contacting the components and the cloth-like catalysts 23, 24 and 31, harmful components such as HC and CO are purified.

According to the structure of the exhaust device 10, since the support bracket 35 for fixing the catalyst member 34 in the diffuser 14 is fixed to the longitudinal center of the catalyst member 34, the total length of the catalyst member 34 is reduced. Even if it changes due to thermal expansion, no stress is applied to the support bracket 35 located at the intermediate portion of the catalyst member 34. Therefore, the deterioration of the durability of the support bracket 35 can be prevented.

The two support arms 35b and 35c of the support bracket 35 extend radially from the catalyst member 34 and are fixed to the inner surface of the diffuser 14. The two support arms 35b and 35c are Since the opening angle A is set in the range of 60 ° to 120 °, the catalyst member 34 can be supported with the highest rigidity against stress caused by engine vibration.

According to the experiment, the opening angle A of the support arms 35b and 35c is 90 with respect to the engine vibration of a predetermined frequency.
It has been clarified that in the case of 応 力, the stress caused by engine vibration is dramatically reduced. Therefore, even if the support bracket 35 is exposed to engine vibration for a long period of time, metal fatigue and the like of the support bracket 35 hardly occur, and
Also in this respect, the deterioration of the durability of the support bracket 35 can be prevented.

Further, in the exhaust device 10, the catalyst member 34 is fixed in the diffuser 14 by one support bracket 35, so that the structure for supporting the catalyst member 34 and the structure of the exhaust device 10 are simplified. Can also contribute greatly.

Further, the catalyst member 34 is
The diffuser 14 accelerates the temperature rise of the catalyst member 34 and keeps the temperature of the catalyst member 34 at a high temperature. In addition, since the catalyst means (37) on the diffuser 14 side is provided so as to overlap the catalyst member 34 in a side view, the performance of the catalyst member 34 is maximized by the synergistic action with the catalyst means (37). Exhaust gas purification efficiency can be greatly improved.

In this embodiment, the catalyst member 34 is a hollow plain tube.
May be a tapered tube, a tube having a gear-shaped cross section, a porous tube, or the like, or the inside of the catalyst member 34 may be filled with a permeable catalyst means such as a honeycomb catalyst.

The exhaust device according to the present invention is not limited to motorcycle engines, but can be applied to any other types of engines.

[0036]

As described above, the exhaust system for an engine according to the present invention includes the engine located at the front of the head, and the unit case provided integrally with the engine and extending rearward. A rear wheel is directly supported at the rear end of the case, and a power unit housing a transmission and a clutch mechanism for shifting the power of the engine and transmitting the power to the rear wheel inside the unit case is vertically rocked on the body frame. An exhaust pipe connected to the engine, an exhaust device main body connected to the exhaust pipe, and an exhaust pipe connected to the engine, and one end disposed inside the exhaust apparatus main body and having one end connected to the scooter type motorcycle freely connected. In an exhaust device for an engine including a diffuser connected to an exhaust pipe and a tubular catalyst member, the diffuser is formed in a tapered cylindrical shape that expands in diameter at an end. The opening on the downstream side protrudes into the exhaust device main body, and the catalyst member is a tapered tube carrying a catalyst substance, and the diffuser is configured so that the catalyst member does not protrude from the downstream opening of the diffuser. The catalyst member is disposed substantially concentrically, a substantially central portion in the longitudinal direction of the catalyst member is fixed to the inner wall of the diffuser by a support bracket, and a flow path of exhaust gas is formed between the diffuser and the catalyst member, and The bracket is formed substantially in the shape of an "M" in the axial direction of the catalyst member and has two support arms extending radially from the catalyst member and fixed to the inner surface of the diffuser, and the opening angle of these support arms. Is set in the range of 60 ° to 120 °.

In this way, even if the overall length of the catalyst member changes due to thermal expansion, no stress is applied to the support bracket located in the middle of the catalyst member, so that the durability of the support bracket is prevented from deteriorating. be able to. Also, since the two support arms of the support bracket support the catalyst member with the highest rigidity against the stress caused by engine vibration,
Also in this respect, the deterioration of the durability of the support bracket can be prevented. In addition, since the catalyst member is fixed in the diffuser by one support bracket, the structure of the exhaust device can be simplified.

Further, since the tapered catalyst member does not protrude from the downstream opening of the diffuser, the temperature rise of the catalyst member is accelerated by the diffuser, and the temperature of the catalyst member is maintained at a high temperature. Therefore, the performance of the catalyst member is maximized by the synergistic action with the above, so that the exhaust gas purification efficiency of the catalyst member can be improved.

In the exhaust system for an engine according to the present invention, the catalyst means is also provided on the diffuser itself, and the catalyst means is overlapped with a catalyst member provided in the diffuser in a side view. The synergistic effect with the above allows the performance of the catalyst member disposed in the diffuser to be maximized, and the exhaust gas purification efficiency can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a left side view of a motorcycle provided with an exhaust device according to the present invention.

FIG. 2 is a cross-sectional view of the exhaust device taken along the line II-II of FIG.

FIG. 3 is a longitudinal sectional view of the diffuser and the catalyst member, taken along line III-III in FIG. 2, showing an embodiment of the present invention.

FIG. 4 is a perspective view of a catalyst member showing a conventional technique.

[Explanation of symbols]

 2 Body frame 3 Power unit 5 Engine 6 Unit case 7 Rear wheel 10 Exhaust device 11 Exhaust pipe 12 Exhaust device body 13 Silencer 14 Diffuser 15 Diffuser downstream opening 34 Catalyst member 35 Support bracket 35a, 35b Support arm of support bracket 37 Diffuser -Like catalyst as a catalyst means of the above A Opening angle of the support arm

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01N 3/28 F01N 7/08

Claims (2)

(57) [Claims] 1. An engine, comprising: an engine located at a frontal head; and a unit case provided integrally with the engine and extending rearward, wherein a rear wheel is directly supported at a rearmost portion of the unit case, and A scooter-type motorcycle in which a power unit housing a transmission and a clutch mechanism for shifting the power of the engine and transmitting the power to the rear wheel is slidably coupled to a vehicle body frame,
An exhaust pipe connected to the engine, an exhaust device main body connected to the exhaust pipe, a diffuser disposed inside the exhaust device main body and having one end communicating with the exhaust pipe, and a tubular catalyst member. In the exhaust device for an engine provided with the above, the diffuser is formed in a tapered cylindrical shape that expands in diameter at the end, and an opening on the downstream side is inserted into the interior of the exhaust device main body, and the catalyst member carries a catalyst substance. The catalyst member is disposed substantially concentrically within the diffuser so as not to protrude from the downstream opening of the diffuser, and a substantially central portion in the longitudinal direction of the catalyst member is formed on the inner wall of the diffuser by a support bracket. Fixing, forming an exhaust gas flow passage between the diffuser and the catalyst member, and attaching the support bracket to the catalyst member in the axial direction And has two support arms extending substantially radially from the catalyst member and fixed to the inner surface of the diffuser, and these support arms have an opening angle in the range of 60 ° to 120 °. An exhaust device for an engine, wherein the exhaust device is set to: 2. The exhaust system for an engine according to claim 1, wherein the diffuser itself is provided with a catalyst means, and the catalyst means overlaps with a catalyst member disposed in the diffuser in a side view.