JP3321924B2 - 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 exhaust system for an engine in which a plurality of exhaust pipes are gathered into one exhaust pipe.

[0002]

2. Description of the Related Art FIG. 4 is a plan view showing a conventional collective exhaust system used for a motorcycle, for example. The exhaust device 100 includes two exhaust pipes 101 and 102 connected to an exhaust port of an engine, and a pipe collecting member 103 that collects the most downstream parts of the exhaust pipes 101 and 102. The member 103 is connected to an exhaust pipe 104 following an exhaust muffler or the like. Generally, the exhaust pipe 1
The lowermost portions of the pipes 01 and 102 are welded and fixed to the upstream end of the pipe collecting member 103.

In this structure, an exhaust pipe 10
Since the cross-sectional area change at the gathering portion A of 1,102 is large, stress generated due to thermal expansion or running vibration of the motorcycle tends to concentrate on the gathering portion A, and in some cases, the gathering portion A may be damaged. . In order to prevent this, a reinforcing pipe 1 is provided around the outermost downstream portion of the exhaust pipes 101 and 102.
05 is densely inserted and fixed to form this partial double pipe structure, and the reinforcing pipe 105 is welded to the upstream end of the pipe collecting member 103.

In such a case, the stress applied to the collecting portion A is increased by the reinforcing pipe 105 to the exhaust pipe 101,
Since it is dispersed to the side 102, stress concentration in the gathering portion A is reduced, and breakage is avoided. Here, the reinforcing pipe 105
If the length is extended along the exhaust pipes 101 and 102, the concentration of stress on the gathering portion A can be more effectively reduced.

[0005]

The reinforcing pipe 10
In order to form the exhaust pipes 101 and 102 into a double pipe structure by using the pipe 5, it is preferable that the lowermost parts of the exhaust pipes 101 and 102 are straight pipes. When this portion is curved, the reinforcing pipe 105 is inserted into the exhaust pipes 101 and 102 and fixed beforehand before the bending of the exhaust pipes 101 and 102, and then the exhaust pipes 101 and 102 and the reinforcing pipe 105 are simultaneously bent. However, at this time, the chucking property of the reinforcing tube 105 becomes very poor, and the bending process becomes difficult.

However, in many motorcycle exhaust systems, since the vicinity of the most downstream portion of the exhaust pipes 101 and 102 is curved and connected to the pipe collecting member 103, the reinforcing pipe 105 is provided to avoid the curved portion. If
As is clear from FIG. 4, the exhaust pipe 101,
The reinforcing pipe 105 can be provided only in a small straight pipe portion formed between the curved portion 102 and the pipe collecting member 103. Therefore, the length of the reinforcing pipe 105 is reduced,
Sufficient stress relaxation cannot be achieved.

In recent years, the length of the exhaust pipes 101 and 102 has been shortened by many motorcycles having a cowling that covers the front half of the vehicle body, increasing the size of a radiator and an oil cooler, and lowering the engine position. Tend to be. For this reason, the straight pipe portion where the reinforcing pipe 105 is to be provided becomes shorter and shorter, and the reinforcing pipe 105 is difficult to be provided.

The present invention has been made in order to solve the above problems, and it is possible to effectively alleviate the stress concentration in the exhaust pipe assembly and avoid breakage irrespective of the shape near the most downstream portion of the exhaust pipe. It is an object of the present invention to provide a simple engine exhaust device.

[0009]

In order to achieve the above object, an exhaust system for an engine according to the present invention comprises a plurality of exhaust pipes connected to an exhaust port of an engine and a lowermost portion of the exhaust pipes. A pipe assembly member, and a reinforcing pipe is closely inserted and fixed around the outermost downstream portion of the exhaust pipe to form a double pipe structure, and the double pipe portion is fixed to the pipe assembly member. In the exhaust device of a type engine, the reinforcing pipe is extended to overlap with a straight pipe portion upstream of a curved portion near the exhaust pipe lowermost downstream portion, and formed between the reinforcing pipe and the pipe assembly member. The air gap is closed by a welding material.

[0010]

According to the exhaust system for an engine having the above-described structure,
Because the reinforcing pipe was extended until it overlapped the straight pipe part on the upstream side from the curved part near the exhaust pipe most downstream part, regardless of the shape near the exhaust pipe most downstream part,
The length of the reinforcing tube can be made sufficiently long. For this reason, the stress applied to the exhaust pipe gathering portion is efficiently dispersed to the exhaust pipe side by the reinforcing pipe, and the stress concentration in the exhaust pipe gathering portion is reduced, thereby avoiding breakage.

Moreover, since the most upstream part of the reinforcing pipe is a straight tube, it is possible to reliably chuck the most upstream part of the reinforcing pipe together with the exhaust pipe when the reinforcing pipe is inserted into the exhaust pipe and simultaneously bent. it can. For this reason, the bending processability of the exhaust pipe and the reinforcing pipe is kept very good. In addition, since a gap formed between the reinforcing pipe and the pipe collecting member in the exhaust pipe collecting portion is closed by the welding material, a sudden change in cross-sectional area in the exhaust pipe collecting portion can be reduced, and the exhaust pipe collecting portion can be used. The applied stress can be more efficiently dispersed, and the durability of the exhaust device can be increased.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a collective exhaust device according to the present invention. The exhaust device 1 includes four exhaust pipes 2 to 5 connected to an exhaust port of an engine, and the exhaust pipes 2 and 3 are connected to a pipe collecting member 6.
And the exhaust pipes 4 and 5 are pipe assembly members 7
Are fixed to each other. Exhaust pipes 8 and 9 are connected to the rear portions of the pipe assembly members 6 and 7, respectively. The exhaust pipes 8 and 9 are connected to the pipe assembly member 11 and the pipe assembly member 11 is connected to the exhaust muffler 13 via the tail pipe 12. It is connected. An exhaust hole 14 is provided at the rear of the exhaust muffler 13.

FIG. 2 is an enlarged plan view of the exhaust pipes 2, 3 and the pipe collecting member 6, the exhaust pipe 8, and the like. FIG. 3 is a longitudinal sectional view taken along the line III-III of FIG.
At the most upstream part of the exhaust pipes 2, 3, a base part 15 fitted to an exhaust port of the engine is provided, and a fixing bracket 16 is provided. The exhaust pipes 2 and 3 are curvedly extended from the base 15 and are connected to the pipe collecting member 6 in a U-turn.

A reinforcing pipe 17 is densely inserted and fixed around the outermost downstream portion of the exhaust pipes 2 and 3, and this portion has a double pipe structure. The reinforcing pipe 17 is bent together with the exhaust pipes 2 and 3, and is fixed to the exhaust pipes 2 and 3 by welding or the like. Here, the reinforcing pipe 17 is extended until it overlaps with the straight pipe part C upstream of the curved part B near the most downstream part of the exhaust pipes 2 and 3.

As shown in FIG. 3, the pipe assembly 6 is formed, for example, by welding an upper half portion 6a and a lower half portion 6b at a central welding allowance 6c, and has an approximately figure-shaped vertical cross-sectional shape. Is configured. Then, as described above, the reinforcing pipe 1
The lowermost portion of the exhaust pipes 2 and 3 provided with the double pipe structure 7 is inserted into the pipe collecting member 6, and the outer peripheral portion of the reinforcing pipe 17 is welded to the pipe collecting member 6. Here, the gap 18 formed between the reinforcing pipe 17 and the pipe collecting member 6 is closed by the welding material.

According to the exhaust device 1 configured as described above, the reinforcing pipe 17 is extended until it overlaps the straight pipe portion C upstream of the curved portion B near the most downstream portion of the exhaust pipes 2 and 3. Therefore, the length of the reinforcing pipe 17 can be made sufficiently long regardless of the shape of the exhaust pipes 2 and 3 in the vicinity of the most downstream portion. For this reason, the stress generated by thermal expansion, the running vibration of the motorcycle, and the like, causes the exhaust pipe 2,
3, the stress is efficiently dispersed to the exhaust pipes 2 and 3 through the reinforcing pipe 17,
Stress concentration in the gathering portion A is reduced, and breakage is avoided.

Moreover, since the most upstream part of the reinforcing pipe 17 is a straight tube, when the reinforcing pipe 17 is inserted into the exhaust pipes 2 and 3 and simultaneously bent, the most upstream part of the reinforcing pipe 17 is connected to the exhaust pipe 2. 3 can be reliably chucked. Therefore, the exhaust pipe 2,
The bending workability of the reinforcing pipe 3 and the reinforcing pipe 17 is kept very good. In addition, since the gap 18 formed between the reinforcing pipe 17 and the pipe collecting member 6 in the collecting portion A is closed by the welding material, a sudden change in the cross-sectional area in the collecting portion A can be reduced. The stress applied to the portion A can be more efficiently dispersed, and the durability of the exhaust device 1 can be increased.

The exhaust pipes 4 and 4 shown in FIG.
5, the pipe assembly 7, and the exhaust pipe 9 are assembled in the same manner as in FIG.

[0019]

As described above, the exhaust system for an engine according to the present invention comprises a plurality of exhaust pipes connected to the exhaust port of the engine and a pipe collecting member for collecting the most downstream portion of the exhaust pipe. A reinforcement pipe is densely inserted and fixed around the outermost downstream portion of the exhaust pipe to form a double-pipe structure, and this double-pipe section is fixed to the pipe collecting member. In the device, the reinforcing pipe is extended until it overlaps with a straight pipe portion upstream of the curved portion near the exhaust pipe most downstream portion, and a gap formed between the reinforcing pipe and the pipe assembly member is welded with a welding material. It is characterized by being closed.

Therefore, the length of the reinforcing pipe can be sufficiently long irrespective of the shape near the most downstream portion of the exhaust pipe, so that the stress applied to the exhaust pipe collecting portion is efficiently reduced by the reinforcing pipe toward the exhaust pipe. It is well-dispersed, and stress concentration at the exhaust pipe gathering portion is reduced, thereby avoiding breakage.

Moreover, since the most upstream part of the reinforcing pipe is a straight tube, the most upstream part of the reinforcing pipe can be reliably chucked together with the exhaust pipe when the reinforcing pipe is inserted into the exhaust pipe and simultaneously bent. it can. For this reason, the bending processability of the exhaust pipe and the reinforcing pipe is kept very good. In addition, since a gap formed between the reinforcing pipe and the pipe collecting member in the exhaust pipe collecting portion is closed by the welding material, a sudden change in cross-sectional area in the exhaust pipe collecting portion can be reduced, and the exhaust pipe collecting portion can be used. The applied stress can be more efficiently dispersed, and the durability of the exhaust device can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view of a collective exhaust device according to the present invention.

FIG. 2 shows an embodiment of the present invention, and is an enlarged plan view of an exhaust pipe, a pipe assembly, an exhaust pipe, and the like.

FIG. 3 is a longitudinal sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a plan view of an exhaust device showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust device 2,3,4,5 Exhaust pipe 6,7 Pipe collecting member 8,9 Exhaust pipe 13 Exhaust muffler 17 Reinforcement pipe 18 Air gap A Exhaust pipe gathering part B Curved part near the most downstream part of exhaust pipe C Curved part Straight pipe upstream from B

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Claims (1)

(57) [Claims] A plurality of exhaust pipes connected to an exhaust port of an engine; and a pipe collecting member for collecting a most downstream portion of the exhaust pipe, wherein a reinforcing pipe is densely inserted around the outermost downstream portion of the exhaust pipe. In a collective engine exhaust device in which the portion is fixed to form a double pipe structure and the double pipe portion is fixed to the pipe collecting member, in the exhaust device of the collective type, the reinforcing pipe is bent toward the most downstream portion of the exhaust pipe. An exhaust device for an engine, wherein the exhaust device extends until it overlaps with a straight pipe portion on the upstream side, and a gap formed between the reinforcing pipe and the pipe collecting member is closed by a welding material.