JP2002235534A - Exhaust system for motorcycle - Google Patents

Abstract

(57) Abstract: A bent pipe (52) having a plurality of communication holes (58) penetrating a cylindrical wall, a wire mesh (55) covering the outer circumference of the bent pipe (52) so as to cover the communication holes (58), and a bent pipe. An exhaust gas reaction chamber 61 composed of an outer cylinder 51 covering a curved pipe 52 at a predetermined interval C from the outer surface of the exhaust pipe 52 is provided in the exhaust pipe 43. [Effect] After sudden deceleration, etc., the exhaust gas containing unburned components that temporarily passes through the exhaust pipe can be burned by contact with the hot wire mesh in the exhaust gas reaction chamber, and the exhaust gas is exhausted. Combustion in the pipe or in the downstream muffler can be prevented. Therefore, noise generated from the exhaust device can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle exhaust system suitable for preventing abnormal combustion in a muffler and reducing manufacturing costs.

[0002]

2. Description of the Related Art As an exhaust device for a motorcycle, for example, Japanese Patent Application Laid-Open No. 8-303236, "Exhaust Purification Device for Internal Combustion Engine" is known. In FIG. 3 of the above publication, a second exhaust pipe 12 is connected to an end of a first exhaust pipe 11 connected to an engine, and a third exhaust pipe 12 is connected to an end of the second exhaust pipe 12 and extends toward a muffler.
An exhaust device 5 is described in which an exhaust pipe 13 is connected, and an inner pipe 14 formed of a perforated plate in the second exhaust pipe 12 and having a noble metal adhered to a wall surface is disposed in the second exhaust pipe 12.

[0003]

For example, when the vehicle suddenly decelerates, the air-fuel mixture immediately after the rapid deceleration becomes rich, and unburned components that do not burn in the combustion chamber may be discharged to the exhaust pipe.
This unburned component (unburned gas) may cause abnormal combustion in the muffler and generate noise.

In the technique disclosed in the above publication, for example, the exhaust device 5
When exhaust gas containing a large amount of unburned components flows into the inside, specific components to be purified in the unburned components can be removed, but it is difficult to suppress abnormal combustion. Also, since the inner tube 4 is made of precious metal, it is expensive.
The manufacturing cost of the exhaust device 5 is increased.

Therefore, an object of the present invention is to prevent the occurrence of abnormal combustion in the exhaust device of a motorcycle,
It is to reduce the manufacturing cost.

[0006]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide an inner cylinder having a plurality of holes penetrating a cylinder wall, and a wire mesh covering an outer periphery of the inner cylinder so as to cover the holes. And an exhaust gas reaction chamber comprising an outer cylinder covered with the inner cylinder at a predetermined interval from the outer surface of the inner cylinder is provided in the middle of the exhaust pipe.

[0007] Particularly after a sudden deceleration, etc., the exhaust gas containing a large amount of unburned components that temporarily passes through the exhaust pipe can be burned by contact with the hot wire mesh in the exhaust gas reaction chamber, and the exhaust gas can be exhausted. Gas can be prevented from burning in the downstream muffler. Therefore, noise generated from the exhaust device can be prevented.

According to a second aspect of the present invention, the width of the wire mesh is made equal to the outer peripheral length of the inner cylinder, and the ends of the wire mesh are welded in the middle of the holes. By welding the ends of the wire mesh between the holes, the wire mesh can be easily fixed to the inner cylinder, and the welding point of the wire mesh reduces the flow of exhaust gas passing through the hole. There is no hindrance.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a side view of a motorcycle provided with an exhaust device according to the present invention. In a motorcycle 10, a head pipe 12 is attached to a front portion of a body frame 11, and a handle 13 and a front fork 14 are attached to the head pipe 12. The front fork 14 is attached to the front fork 14
5, a power unit 18 is suspended between a rear cushion unit 17 having an upper end attached to a rear portion of the body frame 11 and an intermediate portion of the body frame 11, and a rear wheel 21 is attached to a rear end of the power unit 18.
A carburetor 25 is connected via an intake pipe 24 to a cylinder head 23 of an engine 22 which constitutes a front portion of the engine 22, an air cleaner 26 is connected to the carburetor 25, and a scooter type vehicle is also provided with an exhaust device 27 attached to the cylinder head 23. is there.

Here, 31 is a front cover, 32 is a front inner cover, 33 is a front fender, 34 is a floor step, 35 is a seat, 36 is a body cover,
37 is a spare tire, 38 is a rear fender, and 39 is a stand.

FIG. 2 is a side view of the exhaust device according to the present invention. The exhaust device 27 has a front end at the cylinder head 23 (FIG. 1).
), And a muffler 44 connected to the rear end of the exhaust pipe 43. The muffler 44 is provided with mounting brackets 45 and 46 for mounting to the power unit 18 (see FIG. 1).

FIG. 3 is a plan view of the exhaust device according to the present invention.
(See FIG. 1). A flange 48 is provided for attachment to the flange 48, an outer cylinder 51 connected to the flange 48, and a bent pipe 52 connected to the outer cylinder 51 as an inner cylinder. The muffler 44 has a heat shield plate 53 attached to the side surface.

FIG. 4 is a sectional view taken along a line 4-4 in FIG. 3, and the exhaust pipe 43 includes a flange portion 48 and a J-shaped outer cylinder 5.
1 and a bent pipe 5 having an end located inside the outer cylinder 51.
2 and a wire mesh 55 interposed between each of the outer cylinder 51 and the bent pipe 52.

The flange portion 48 is provided on the cylinder head 23.
(See FIG. 1) Mounting holes 48a, 48a for mounting to
A flange plate 56 (see FIG. 3) is opened, and a cylindrical collar 57 attached inside the flange plate 56 is provided.
The flange 57 is attached to the outer cylinder 51 by inserting the collar 57 into the end of the outer cylinder 51 and welding a flange plate 56 to the outer cylinder 51. The outer cylinder 51 is a cylinder half 51a, 5 which is formed by cutting a cylinder bent in a J-shape substantially in half in the longitudinal direction.
1b. The outer cylinder 51 has four slits (not shown) for welding the flanges 48.

The bent pipe 52 is formed by opening communication holes 58... (. It is. The wire mesh 55 is attached to the bent pipe 52 and covers the communication holes 58. Reference numeral 61 denotes an exhaust gas reaction chamber formed by separating the inner surface of the outer cylinder 51 from the outer surface of the bent pipe 52 by a predetermined distance C. (Details will be described later.)

FIG. 5 is a sectional view taken along the line 5-5 in FIG. 3. The tubular half 51b has edges 51c, 51c spread outward, and these edges 51c, 51c are connected to an edge 51d of the tubular half 51a. , 5
The outer cylinder 51 is formed by overlapping and welding on 1d.

The wire mesh 55 has a width W (see FIG. 7A) equal to the outer peripheral length of the bent tube 52, and is wound around the bent tube 52 and welded at its ends. The ends of the wire mesh 55 may be welded together with the outer peripheral surface of the bent tube 52. The communication hole 58 of the bent pipe 52 is opened at every 90 ° in the circumferential direction.

FIG. 6 is a perspective view for explaining the inside of the exhaust device according to the present invention, and shows a bent pipe 52 and a wire mesh 55.
In the present invention, the width W of the expanded wire mesh 55 (see FIG. 7A)
Is the same as the outer peripheral length of the bent pipe 52, and the ends 55a and 55b of the wire mesh 55 are welded in the middle between the communication holes 58. Reference numeral 63 denotes a welding portion between the ends 55a and 55b of the wire mesh 55.

The above welding position is determined by the length L of the wire mesh 55.
(Dimension along the longitudinal direction of the bent pipe 52), if it is substantially at the center, the end 5 of the wire mesh 55 on the distal end side of the bent pipe 55
4c and the other end 55d can be pressed by the outer tube 51 without welding, as shown in FIG. 4, so that the number of welding points can be reduced and the wire mesh 55 can be easily fixed to the bent pipe 52. can do. Further, since the welding is performed in the middle between the communication holes 58, the flow of the exhaust gas passing through the communication holes 58 is not hindered by the welding portion 63 of the wire mesh 55.

In the present embodiment, in FIG. 6, the communication hole 58 of the bent pipe 52
6 along the longitudinal direction of the bent pipe 52
(24 in total), and the communication hole 5
The total cross-sectional area SH of No. 8 is given assuming that the inner diameter of the communication hole 58 is d.
SH = [pi becomes ^{× d 2/4 × 24 =} 6 × π × d 2. Also,
The surface area SB of the portion of the bent pipe 52 covered with the wire mesh 55 is
Assuming that the outer diameter of the bent pipe 52 is D and the length of the wire mesh 55 is L, SB = π × D × L.

Accordingly, the ratio of the total cross-sectional area SH of the communication hole 58 to the surface area SB of the bent pipe 52 covered with the wire mesh 55,
That is, the opening ratio R of the communication hole of the bent pipe 52 is R = (SH / S
B) = ((6 × π × d ² ) / (π × D × L))
R = ((6 × d ² ) / (D × L)). Here, as an example, if d = 5 mm, D = 20 mm, and L = 70 mm, R becomes about 10%. As described above, the bent pipe 52 of the present invention has a communication hole opening ratio R smaller than that of a case where a pipe is formed from a generally used perforated plate having a large opening ratio.

If the above-mentioned perforated pipe is used for the exhaust pipe, the resistance when exhaust gas passes through the exhaust pipe increases due to the large number of holes, and the exhaust pressure of the exhaust pipe rises, affecting engine performance, especially engine output. Will be exerted.

In this embodiment, the above-described resistance can be reduced and the engine performance can be maintained by reducing the opening ratio R of the communication hole and arranging the communication holes 58 in the longitudinal direction of the bent pipe 52. can do. Further, by arranging the wire mesh 55 on the outer peripheral side of the bent tube 52, the above-described resistance can be made smaller than that of disposing the wire mesh 55 on the inner peripheral side of the bent tube 52.

Next, the procedure for assembling the exhaust device 27 described above will be described. FIGS. 7A to 7D are operation diagrams for explaining the assembly procedure of the exhaust device according to the present invention. In (a), first, a wire mesh 55 having a width of W is wound around the end of the bent pipe 52 so as to cover the communication holes 58 of the bent pipe 52.
In (b), the ends 55 a and 55 b of the wire mesh 55 are welded to each other at a welding location 63.

In FIG. 5C, the cylinder half 51a is applied to the wire mesh 55 fixed to the bent pipe 52, and the end 5 of the cylinder half 51a is moved.
1e is welded to the bent pipe 52. In (d), the edges 51d and 51d of the cylinder half 51a (the reference numeral 51d on the back side is not shown) are overlapped with the edges 51c and 51c of the cylinder half 51b (the reference numeral 51c on the back is not shown). Stacked cylinder halves 5
The collars 57 of the flange portion 48 are inserted into the ends of 1a and 51b, and the edges 51c and 51c are welded to the outer surface of the cylinder half 51a. In (e), the stacked cylinder halves 51a, 51b
The flange plate 56 of the flange portion 48 is welded to the end of
The assembly of the exhaust pipe 43 is completed.

FIG. 8 is an operation diagram for explaining the operation of the exhaust device according to the present invention. The exhaust gas discharged from the combustion chamber of the engine flows in the exhaust pipe as shown by the arrow in the figure. That is, the exhaust gas contacts the wire mesh 55 at each communication hole 58,
Alternatively, the gas flows through the wire mesh 55 into the exhaust gas reaction chamber 61. As a result, the unburned gas in the exhaust gas burns by touching the hot wire mesh 55. In this case, the combustion proceeds in a wide range within the exhaust pipe 43 by the wire mesh 55 having a relatively large surface area and facing each communication hole 58, so that abnormal combustion does not occur in the muffler.

The reason why the temperature of the wire net 55 becomes high is as follows. The temperature of the bent pipe 52 as the inner cylinder is
In the part covered by 1, the outer cylinder 51 touching the outside air
Higher than the temperature. However, since the portion of the bent pipe 52 that is not covered by the outer cylinder 51 (range A shown in FIG. 4) is in contact with the outside air, the temperature of the part of the bent pipe 52 that is covered by the outer cylinder 51 is lower than that temperature. Affected and lower compared to exhaust gas temperature.

The portion of the wire mesh 55 that does not face the communication hole 58 has a temperature substantially equal to the portion of the bent tube 52 that is covered by the outer cylinder 51, but the portion of the wire mesh 55 that faces the communication hole 58 is directly exhausted. Since the heat capacity of the wire material which is in contact with the gas and has a small wire diameter constituting the wire mesh 55 is small, the temperature of the wire material is almost high, which is almost the temperature of the exhaust gas. This promotes the combustion of unburned components in the exhaust gas. No wire mesh 55, communication hole 5
In the case where only the bent pipe 52 with the opening 8 is open, the bent pipe 52
Since the temperature does not increase as described above, the unburned components in the exhaust gas are not easily burned.

The abnormal combustion often occurs in the muffler 44 (see FIG. 3) in which the exhaust gas tends to stagnate and forms a closed space, rather than in the exhaust pipe 43 through which the exhaust gas flows smoothly. Therefore, if unburned components in the exhaust gas are burned by the wire mesh 55 provided in the middle of the exhaust pipe 43,
It is possible to prevent abnormal combustion from occurring in the muffler 44 located downstream of the muffler.

As described above with reference to FIGS. 3 and 4, the present invention relates to a curved pipe 52 having a plurality of communicating holes 58 penetrating the cylindrical wall, and a curved pipe 52 covering the communicating holes 58. An exhaust gas reaction chamber 61 comprising a metal mesh 55 covering the outer periphery and an outer cylinder 51 covering the bent pipe 52 at a predetermined distance C from the outer surface of the bent pipe 52 is provided in the middle of the exhaust pipe 43. And

In particular, after a sudden deceleration or the like, the exhaust gas temporarily passing through the exhaust pipe 43 and containing a large amount of unburned components is brought into contact with the hot wire mesh 55 in the exhaust gas reaction chamber 61 to burn it. It is possible to prevent the exhaust gas from burning in the exhaust pipe 43 or in the muffler 44 downstream. Therefore, noise generated from the exhaust device 27 can be prevented.

As the wire mesh 55 of the exhaust device 27, a commercially available wire mesh can be used, and since the wire mesh 55 can be easily assembled to the exhaust device 27, the manufacturing cost of the exhaust device 27 can be reduced. be able to.

The communication hole 5 of this embodiment shown in FIG.
8 is 90 degrees in the circumferential direction of the bent pipe 52 as shown in FIG.
However, the number of the communication holes 58 is not limited to 24. However, the number of the communication holes 58 is not limited to 24. Further, the wire mesh 55 is placed on the outer periphery of the bent pipe 52 as shown in FIG. 5, but is not limited to this.
If it is arranged in the exhaust gas reaction chamber 61, it may be separated from the outer peripheral surface of the bent pipe 52.

[0034]

According to the present invention, the following effects are exhibited by the above configuration. The exhaust device for a motorcycle according to claim 1, wherein an inner cylinder having a plurality of holes penetrating the cylinder wall, a wire mesh covering the outer periphery of the inner cylinder so as to cover the holes, and a predetermined distance from an outer surface of the inner cylinder. An exhaust gas reaction chamber consisting of an outer cylinder that is held and covered on the inner cylinder is provided in the middle of the exhaust pipe, so that exhaust gas containing unburned components that temporarily pass through the exhaust pipe, especially after sudden deceleration, etc. Combustion can be achieved by contact with a hot wire mesh in the exhaust gas reaction chamber, and combustion of exhaust gas in the exhaust pipe or in the downstream muffler can be prevented. Therefore, noise generated from the exhaust device can be prevented.

According to a second aspect of the present invention, the width of the wire mesh is made equal to the outer peripheral length of the inner cylinder, and the ends of the wire mesh are connected to each other.
Since the welding was performed between the holes, the wire mesh can be easily fixed to the inner cylinder.
It does not obstruct the flow of exhaust gas through the holes. .

[Brief description of the drawings]

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

FIG. 2 is a side view of the exhaust device according to the present invention.

FIG. 3 is a plan view of an exhaust device according to the present invention.

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 3;

FIG. 6 is a perspective view illustrating the inside of an exhaust device according to the present invention.

FIG. 7 is an operation diagram illustrating an assembly procedure of the exhaust device according to the present invention.

FIG. 8 is an operation diagram illustrating the operation of the exhaust device according to the present invention.

[Explanation of symbols]

10 ... motorcycle, 43 ... exhaust pipe, 51 ... outer cylinder, 52 ...
Inner cylinder (bent tube), 55: wire mesh, 55a, 55b: end of wire mesh, 58: hole (communication hole), 61: exhaust gas reaction chamber,
63: welding position of wire mesh, C: predetermined interval, W: width of wire mesh.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01N 7/18 F01N 7/18

Claims (2)

[Claims] 1. An inner cylinder having a plurality of holes penetrating a cylinder wall, a wire mesh covering an outer periphery of the inner cylinder so as to cover the holes, An exhaust device for a motorcycle, wherein an exhaust gas reaction chamber comprising an outer cylinder covered by a cylinder is provided in the middle of an exhaust pipe. 2. The automatic apparatus according to claim 1, wherein a width of the wire mesh is equal to an outer peripheral length of the inner cylinder, and ends of the wire mesh are welded at an intermediate portion between the holes. Exhaust system for motorcycles.