JP2002195027A - Exhaust muffler for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent output reduction due to installation of a honeycomb-core shape catalyst and to improve exhaust purification efficiency at the same time. SOLUTION: An inner pipe 28, as an extending pipe from an exhaust pipe 11, is arranged in a longitudinal direction inside a cylindrical muffler body 12 to be turned into a U-shape inside of the muffler body 12. The honeycomb- core shape catalyst 31 is connected to an outlet 29 of the inner pipe 28. The catalyst 31 is arranged adjacent to an upstream side of the inner pipe 28, so as to be parallel with the inner pipe 28, and the catalyst 31 and the upstream side of the inner pipe 28 are connected fixedly to each other via a heat transfer and fixing means (catalyst support bracket 48), which is capable of satisfactorily transferring the heat at the upstream side of the inner pipe 28 to the catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust muffler device for a vehicle having a built-in exhaust purification catalyst.

[0002]

2. Description of the Related Art Many exhaust mufflers of vehicles such as motorcycles are provided with a catalyst for purifying harmful components such as HC and CO contained in exhaust gas. A widely used catalyst means is a perforated plate or honeycomb core catalyst inside an exhaust pipe (exhaust pipe) connected to an exhaust port of an engine or a tubular muffler body (expansion chamber) on the downstream side thereof. Some have been installed. The honeycomb core catalyst has a large exhaust contact area with the exhaust gas and thus has excellent exhaust purification performance.

[0003] Such a catalyst causes an oxidation reaction upon contact with the exhaust gas to purify harmful components in the exhaust gas. The exhaust gas purification efficiency increases as the temperature of the exhaust gas increases. Therefore, it is preferable that the catalyst be installed at an upstream portion of the exhaust gas flow path having a relatively high exhaust gas temperature.

[0004]

However, if a honeycomb core-like catalyst is installed in the upstream part of the exhaust gas flow passage, the output of the catalyst becomes extremely low due to exhaust resistance.
If a catalyst is installed downstream of the exhaust gas flow path to avoid this decrease in output, exhaust gas having a sufficiently high temperature cannot be brought into contact with the catalyst, so that exhaust purification efficiency is reduced. This tendency is particularly remarkable in an exhaust muffler device which aims to improve the torque characteristics of the engine by extending the length of the exhaust gas passage by making the exhaust gas passage U-turn inside the muffler body.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an exhaust muffler for a vehicle which can achieve both an avoidance of a decrease in output due to the installation of a honeycomb-shaped catalyst and an improvement in exhaust gas purification efficiency. It is intended to provide a device.

Another object of the present invention is to simplify the structure of the exhaust muffler device and to facilitate manufacture thereof.

[0007]

According to one aspect of the present invention, there is provided a vehicle exhaust muffler according to the present invention.
As described in the above, an inner pipe, which is an extension pipe of the exhaust pipe, is disposed in the longitudinal direction inside the tubular muffler body, and this inner pipe is U-turned inside the muffler body, and the outlet of the inner pipe is formed. A honeycomb core-shaped catalyst is connected to the upstream side of the inner pipe, and the catalyst is disposed in parallel and close to the upstream side of the inner pipe. It is characterized by being connected and fixed by heat transfer fixing means.

According to the above configuration, since the honeycomb core-shaped catalyst is disposed downstream of the exhaust passage, the catalyst is unlikely to have exhaust resistance, and a decrease in output can be avoided. In addition, since the inner pipe makes a U-turn inside the muffler body, the length of the exhaust gas passage is extended, and the torque characteristics of the engine are improved. Then, the temperature of the high-temperature exhaust gas flowing through the upstream portion of the inner pipe is favorably transmitted to the catalyst via the heat transfer fixing means, so that the temperature of the catalyst is sufficiently increased and the exhaust gas purification efficiency is improved.

According to a second aspect of the present invention, there is provided an exhaust muffler device for a vehicle according to the first aspect, wherein the interior of the muffler body is partitioned by a plurality of partition walls in a longitudinal direction of the muffler body. When a plurality of expansion chambers are arranged in a row,
The straight pipe portion before the turn portion and the straight pipe portion after the U-turn portion were penetrated and supported by the partition wall. As a result, the inner pipe is supported by the existing partition, so that there is no need to provide a dedicated support member, and the structure of the exhaust muffler device can be simplified.

Further, according to a third aspect of the present invention, in the exhaust muffler device for a vehicle according to the third aspect, the U-turn portion of the inner pipe is formed by changing a U-turn portion of the plurality of expansion chambers. The muffler body was disposed in the second expansion chamber as viewed from the exhaust pipe connection portion. In this case, the partition between the second and third expansion chambers and the partition after that need not pass through the straight portion of the inner pipe. The inner diameter of the communication pipe can be increased, thereby reducing the exhaust resistance and avoiding a decrease in output.

According to a fourth aspect of the present invention, in the vehicle exhaust muffler device according to the fourth aspect of the present invention, the inner pipe is formed as a U-shaped pipe forming a U-turn portion. And straight pipes forming the straight pipe portions on the upstream and downstream sides. In this case, 1
Since it is not necessary to form a U-turn portion by bending the pipe material, it is possible to reduce the number of processing steps and to facilitate manufacture of the exhaust muffler device.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a left side view of a scooter type motorcycle to which an exhaust muffler device according to the present invention is applied.
In the motorcycle 1, a front fork 3 supporting a front wheel 2 is pivotally mounted on a front part of a vehicle body with a handlebar 4 so as to be rotatable left and right, and a seat 5 is provided on a rear half portion of the vehicle body. A step board 6 on which an occupant's foot rests is formed in the gap between the handlebar 4 and the handlebar 4.

An engine unit (not shown) is provided below a rear portion of the step board 6, and a rear wheel 8 is supported at a rear end of a drive unit 7 extending rearward from the engine unit. The exhaust muffler device 10 of the engine unit is installed so as to extend rearward.

As shown in FIG. 2, the exhaust muffler device 10 has a tubular muffler body 12 connected to an exhaust pipe 11 extending rearward from an exhaust port of an engine unit. The muffler body 12 is disposed on the right side of the rear wheel 8 and is angled obliquely rearward and upward substantially along the vehicle front-rear direction. On its inner surface, two front and rear mounting brackets 13 for fixing to the vehicle body are provided.
14 are provided.

FIG. 3 is a longitudinal sectional view of the exhaust muffler device 10 showing an embodiment of the present invention, FIG. 4 is a view taken in the direction of the arrow IV in FIG. 3, and FIGS. 3 V-V
FIG. 7 is a longitudinal sectional view taken along lines VI-VI, VII-VII.

The outer shell of the muffler body 12 is composed of a pair of left and right semi-cylindrical body halves 16L and 16R, which are joined in the middle, and a tubular inner body having a diameter slightly smaller than the inner circumference thereof. 17 are coaxially arranged. The inner body 17 is formed by a porous plate (punching plate), and both ends thereof are fixed to inner peripheral portions of both ends of the body half bodies 16L and 16R via spacers 18 and 19. The body half 16L,
The space between 16R and the inner body 17 is filled with a sound insulating material such as glass wool.

A funnel-shaped front cover 21 is mounted on the front spacer 18, and a bowl-shaped tail cover 22, 23 is mounted on the rear spacer 19, so that sound is muffled therebetween. The insulation is filled.

Further, two partition walls 24 and 25 are provided at an intermediate portion inside the inner body 17, whereby the inner space of the inner body 17 is partitioned into three expansion chambers 26a, 26b and 26c arranged in the longitudinal direction. ing.

The muffler body 1 configured as described above
Inside 2, an inner pipe 28 which is an extension pipe of the exhaust pipe 11 is disposed in the longitudinal direction. The inner pipe 28 extends rearward in the muffler body 12 from the front cover 21, turns in a U-turn in the second expansion chamber 26 b from the front, turns forward, and has an outlet 29 in the first expansion chamber 26 a. Is located. A honeycomb core-shaped catalyst 31 is connected and fixed to the outlet portion 29 via a diffuser tube 30.

The inner pipe 28 has a three-piece structure, and comprises a U-shaped pipe 33 forming a U-turn portion and straight pipes 34 and 35 forming upstream and downstream straight pipe portions, respectively. Have been. The front end of the straight pipe 34 is enlarged by one step to form a fitting portion 36, and the outer periphery of the fitting portion 36 is fixed to the inner periphery of the converging portion of the front cover 21, and the inner periphery of the fitting portion 36 is exhausted. The end of the pipe 11 is fitted and fixed.

The straight pipe 34 and the straight pipe 35 of the inner pipe 28 are penetrated and supported by the partition wall 24 separating the first expansion chamber 26a and the second expansion chamber 26b from the front.
The U-tube 33 is disposed in the second expansion chamber 26b.

In the muffler body 12, two long and short communication pipes 38, 39 are arranged in parallel with the inner pipe 28 (straight pipes 34, 35). The longer communication pipe 38 is penetrated and supported by the partition wall 24 and the partition wall 25, and has a front end opening into the first expansion chamber 26a from the front and a rear end opening into the third expansion chamber 26c. The shorter communication pipe 39 is penetrated and supported by the partition wall 25, and its front end is opened into the second expansion chamber 26b, and its rear end is connected to the third expansion chamber 26b.
Open in c. Note that the rear end side of the communication pipe 39 is closed by a cap 40, and a section 41 in front of the cap 40 is porous.

Further, a tail pipe 43 is provided so as to penetrate through the partition wall 25 and the tail covers 22 and 23, and the front end of the tail pipe 43 has the second expansion chamber 2 from the front.
6b, and the rear end is open to the outside.

The outlet 2 of the inner pipe 28
The catalyst 31 connected to the pipe 9 is disposed in parallel and close to the upstream portion of the inner pipe 28 (upstream of the straight pipe 34), and the catalyst 31 and the straight pipe 34 are connected by heat transfer fixing means. Fixed. The heat transfer fixing means is a straight pipe 34.
Is configured to be able to transmit the heat to the catalyst 31 satisfactorily.

FIGS. 3 and 7 show the first heat transfer fixing means.
An example is shown. In the first embodiment, a band-shaped plate made of a metal such as stainless steel or nickel, which has a high heat transfer coefficient and excellent heat resistance, is bent into a substantially U-shape.
, And a catalyst support bracket 48 having a pair of support portions 46 and a pair of fixing pieces 47 to form heat transfer fixing means.

The plate thickness of the catalyst support bracket 48 is set to be sufficiently thicker than the thickness of the pipe material constituting the straight pipe 34, so that the heat transfer property is improved. The curved portion 45 is formed to be curved so as to fit to the outer peripheral surface of the straight tube 34, and the fixing piece 47 is formed to be curved to fit to the outer peripheral surface of the catalyst 31. Welded and fixed to the surface.

In the exhaust muffler device 10 configured as described above, the exhaust gas discharged from the engine unit enters the inner pipe 28 inside the muffler body 12 via the exhaust pipe 11 and is connected to the downstream end of the inner pipe 28. By passing through the catalyst 31
After purifying harmful components such as C and CO, the expansion chamber 26
a, and then into the expansion chamber 26c through the communication pipe 38, and further into the expansion chamber 26b through the communication pipe 39, and expands in each of the expansion chambers 26a, 26b, 26c. It is discharged from the pipe 43 to the outside.

In this exhaust muffler device 10, since the honeycomb core-shaped catalyst 31 is disposed at the most downstream portion of the inner pipe 28, the catalyst 31 is unlikely to have exhaust resistance.
A decrease in the output of the engine unit can be avoided. In addition, since the length of the inner pipe 28 having a U-turn structure in the muffler body 12 is sufficiently long, the torque characteristics of the engine unit are also improved.

The temperature of the high-temperature exhaust gas flowing through the straight pipe 34, which is the upstream portion of the inner pipe 28, is controlled by the catalyst support bracket 48 as a heat transfer fixing means.
Therefore, the temperature of the catalyst 31 is sufficiently increased, and the exhaust gas purification efficiency of the catalyst 31 is improved. Therefore, it is possible to avoid both a reduction in output due to the provision of the honeycomb core-shaped catalyst 31 and an improvement in exhaust gas purification efficiency.

In the exhaust muffler device 10, the straight pipes 34, 35 of the inner pipe 28 are connected to the existing partition wall 24.
Therefore, it is not necessary to provide a dedicated support member, and in this regard, the number of parts of the exhaust muffler device 10 can be reduced and the structure can be simplified.

Further, since the U-turn portion (U-shaped pipe 33) of the inner pipe 28 is arranged in the second expansion chamber 26b from the front, the second expansion chamber 26b and the third expansion chamber 2
6c, the straight pipe 3 of the inner pipe 28
There is no need to penetrate 4,35. Therefore, the partition 2
The inner diameters of the other communication pipes 38, 39, etc., penetrating through 5 can be increased, thereby reducing the exhaust resistance and avoiding a decrease in the output of the engine unit.

The inner pipe 28 is connected to the U-shaped pipe 33.
And the straight pipes 34 and 35, it is not necessary to perform bending on one pipe material to form an inner pipe having a U-turn portion. Thus, the production of the exhaust muffler device 10 can be facilitated.

FIG. 8 shows a second embodiment of the heat transfer fixing means. The catalyst support bracket 51 serving as the heat transfer fixing means has a two-piece structure different from the one-piece catalyst support bracket 48 of the first embodiment, and each includes a support portion 52, a fixing piece 53, and a fixing piece 54. ing. The fixing pieces 53 and 54 are provided with a curvature that fits the outer peripheral surfaces of the straight pipe 34 and the catalyst 31, respectively.
3 is welded and fixed to the straight pipe 34, and the fixing piece 54 is welded to the catalyst 31.

The distance between the pair of support portions 52 is narrower than that of the catalyst support bracket 48 of the first embodiment. The length of the support portions 52 is shorter and the area of the fixing piece 54 is larger. As described above, by shortening the length of the support portion 52 and increasing the area of the fixing piece 54, the heat of the straight pipe 34 is transmitted to the catalyst 31 without loss, and the exhaust purification efficiency of the catalyst 31 is further improved. Can be done.

FIG. 9 shows a third embodiment of the heat transfer fixing means. Here, a catalyst support block 56 is used as the heat transfer fixing means. The catalyst support block 56 is made of a metal such as stainless steel or nickel having a high heat transfer coefficient and excellent heat resistance, and a curved surface 57 provided at one end thereof is fixed to the outer peripheral surface of the straight tube 34 and the other end thereof The provided curved surface 58 is fixed to the outer peripheral surface of the catalyst 31. In this way, by configuring the heat transfer fixing means in a block shape, the heat transfer coefficient is further increased, and the heat of the straight pipe 34 is transferred to the catalyst 3.
1 can be transmitted.

FIG. 10 shows a fourth embodiment of the heat transfer fixing means. Here, a groove 61 is formed in the catalyst 31 along the axial direction of the straight tube 34, and the straight tube 34 is formed in the groove 61.
And the periphery of the catalyst 31 and the straight tube 34 is bound by a metal band 62. Thus, the catalyst 31 and the straight tube 34
The heat of the straight tube 34 can be transmitted to the catalyst 31 to the maximum with a very simple structure, and the exhaust gas purification efficiency of the catalyst 31 can be increased by making the very simple structure.

The configuration of the above embodiment is not limited to the exhaust muffler device of a motorcycle, but can be widely applied to exhaust muffler devices of other types of vehicles such as automobiles.

[0039]

As described above, the exhaust muffler device for a vehicle according to the present invention has an inner pipe, which is an extension pipe of an exhaust pipe, disposed in the longitudinal direction inside a cylindrical muffler body. And a U-turn inside the muffler body, a honeycomb core-shaped catalyst is connected to the outlet of the inner pipe, and this catalyst is arranged in parallel and close to the upstream part of the inner pipe, so that the catalyst is located between the catalyst and the upstream part of the inner pipe. Are connected and fixed by heat transfer fixing means capable of transmitting the heat of the inner pipe upstream portion to the catalyst satisfactorily.According to this configuration, the output reduction due to the installation of the honeycomb core-shaped catalyst is reduced. Avoidance and improvement of exhaust purification efficiency can both be achieved.

[Brief description of the drawings]

FIG. 1 is a left side view of a scooter type motorcycle to which an exhaust muffler device according to the present invention is applied.

FIG. 2 is an enlarged left side view of the exhaust muffler device.

FIG. 3 is a longitudinal sectional view of an exhaust muffler device showing an embodiment of the present invention.

4 is a view taken in the direction of the arrow IV in FIG. 3;

FIG. 5 is a longitudinal sectional view taken along the line VV of FIG. 3;

FIG. 6 is a longitudinal sectional view taken along the line VI-VI in FIG. 3;

FIG. 7 is a view showing a first embodiment of the heat transfer fixing means by a longitudinal section along a line VII-VII in FIG. 3;

FIG. 8 is a longitudinal sectional view showing a second embodiment of the heat transfer fixing means.

FIG. 9 is a longitudinal sectional view showing a third embodiment of the heat transfer fixing means.

FIG. 10 is a longitudinal sectional view showing a fourth embodiment of the heat transfer fixing means.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Motorcycle as a vehicle 10 Exhaust muffler device 11 Exhaust pipe 12 Muffler body 24, 25 Partition wall 26a, 26b, 26c Expansion room 28 Inner pipe 30 Diffuser pipe 31 Catalyst 33 U-shaped pipe 34 which constitutes the U-turn part of inner pipe 34, 35 Straight pipes constituting the straight pipe portion of the inner pipe 38, 39 Communication pipe 43 Tail pipe 48 Catalyst support bracket which is the first embodiment of the heat transfer fixing means 51 Catalyst support which is the second embodiment of the heat transfer fixing means Bracket 56 Catalyst support block which is a third embodiment of heat transfer fixing means 61 Groove which constitutes a fourth embodiment of heat transfer fixing means 62 Metal band which constitutes a fourth embodiment of heat transfer fixing means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F01N 3/28 301 B01D 53/36 BF Term (Reference) 3G004 AA02 BA03 BA06 CA04 DA07 DA08 DA09 DA14 DA21 EA05 FA04 FA07 3G091 AA02 AA03 AB01 BA04 BA38 BA39 CA01 GA06 GB01Z HA05 4D048 AA06 AA13 AA18 AB01 AB02 BB02 CC25 CC42 CC51

Claims (4)

[Claims] 1. An inner pipe, which is an extension pipe of an exhaust pipe, is disposed in a longitudinal direction inside a tubular muffler body, and this inner pipe is U-turned inside the muffler body, and is provided at an outlet of the inner pipe. A honeycomb core-shaped catalyst is connected, and this catalyst is arranged in parallel and close to the upstream portion of the inner pipe, and heat can be transferred between the catalyst and the inner pipe upstream portion so that the heat of the inner pipe upstream portion can be transmitted well to the catalyst. An exhaust muffler device for a vehicle, wherein the exhaust muffler device is connected and fixed by transmission fixing means. 2. When the inside of the muffler body is partitioned by a plurality of partitions to define a plurality of expansion chambers arranged in the longitudinal direction of the muffler body, a straight pipe portion before a U-turn portion of the inner pipe. 2. The exhaust muffler device for a vehicle according to claim 1, wherein a straight pipe portion following the U-turn portion and the U-turn portion are penetrated and supported by the partition wall. 3. The U-turn part of the inner pipe,
3. The exhaust muffler device for a vehicle according to claim 2, wherein the exhaust muffler device is disposed in a second one of the plurality of expansion chambers as viewed from an exhaust pipe connecting portion of the muffler body. 4. The inner pipe according to claim 1, wherein the inner pipe comprises a U-shaped pipe forming a U-turn portion and a straight pipe forming upstream and downstream straight pipe portions. Exhaust muffler device for vehicles.