JPH057532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust system for an internal combustion engine, and more particularly to an exhaust system suitable for a multi-cylinder internal combustion engine.

As an exhaust system installed in a vehicle such as a motorcycle equipped with a multi-cylinder engine, multiple exhaust pipes are converged into a box-shaped expansion chamber made of sheet metal, and the exhaust pipe is connected from the exhaust side of this expansion chamber to another exhaust pipe. Some are designed to exhaust air into the atmosphere. Since the expansion chamber is made of sheet metal, if it is configured as is, the wall surface will vibrate due to exhaust pulsation, and a loud shell noise will be generated. Conventionally, measures have been taken to eliminate this shell noise, such as fixing glass wool to the inside of the expansion chamber with punched metal, or fixing struts that extend above and below, but the former method of fixing glass wool increases the weight. In the latter case, the struts provide flow resistance to the exhaust gas, resulting in a reduction in engine output.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an exhaust system for an internal combustion engine that does not increase weight or provide resistance to exhaust gas and can be manufactured at low cost. be.

The present invention achieves the above object by converging a plurality of exhaust pipes connected to an internal combustion engine into a box-shaped expansion chamber made of sheet metal, and from the exhaust side of the expansion chamber to the atmosphere side via another exhaust pipe. In the exhaust device for exhausting air, the plurality of exhaust pipes are deeply inserted into the expansion chamber, and the outer wall of the insertion portion of the exhaust pipes and the inner wall of the expansion chamber are fixed by welding. It is something.

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 1 shows an exhaust system according to the present invention for a motorcycle equipped with a four-cylinder engine.

The four exhaust pipes 1, 1, 1, 1 have their bent front ends connected to respective cylinders of an engine (not shown), and their rear ends connected to a differential user pipe 5 which becomes a part of the exhaust pipes. , 5, 5, 5 to a box-shaped expansion chamber 2 made of sheet metal. The exhaust pipe 1 and the differential user pipe 5 are fastened and fixed by a band 6. Another exhaust pipe 3, 3 is connected to the other end of the expansion chamber 2 and communicates with the atmosphere via a muffler 4.

Figures 2 and 3 show details of two parts of the expansion chamber. The expansion chamber 2 is made of a half-split sheet metal upper plate 2a.
and the lower plate 2b are combined and their joints are welded to form a box shape. A reinforcing rib 8 is provided on the surface of the expansion chamber 2. The differential user pipe 5, which constitutes a part of the exhaust pipe, has its periphery fixed by welding at the entrance end of the expansion chamber 2, and its rear end side is inserted deep inside, so that the outer wall of the insertion part and the expansion chamber 2 It is plug welded to the inner wall and has a fixed structure having a welded portion 7 as shown in FIG.
The exhaust pipe 3 on the exhaust side is fixed by welding around the periphery at the outlet end of the expansion chamber 2, but if necessary, the front end side is inserted deep into the expansion chamber 2 in the same way as the differential user pipe 5, and the inserted part is inserted into the expansion chamber 2. Plug welding may be performed between the inner wall of the

To assemble the upper and lower plates 2a and 2b of the expansion chamber 2, the differential user pipe 5, and the exhaust pipe 3, first, the entire assembly is assembled, welding is performed along the joint between the upper plate 2a and the lower plate 2b, and the differential user pipe is assembled. 5 and the exhaust pipe 3, one half of the circumference along the upper plate 2a or the lower plate 2b may be welded first, and then the remaining half of the circumference may be welded.

According to the above-described exhaust system, the rear ends of the plurality of differential user tubes 5 constituting a part of the exhaust pipe are deeply inserted into the inside of the expansion chamber 2, and the insertion portion is inserted into the expansion chamber 2.
Since the insertion portion of the differential user tube 5 acts as a strength member of the expansion chamber 2, it improves the rigidity of the expansion chamber 2 made of a thin sheet metal. Therefore, the expansion chamber 2 does not vibrate due to the exhaust pulsation and generate a loud shell noise. In addition, unlike the conventional structure in which glass wool is pasted thickly on the inside of the expansion chamber, it does not increase the weight and is low cost. Furthermore, it does not increase the flow resistance of the exhaust air like struts that are stretched over the top and bottom. Nor.

In the above embodiment, the inner wall surface of the expansion chamber 2 and the outer wall surface of the insertion portion of the differential user tube 5 are welded together by plug welding, but this welding may be performed by other welding methods. Furthermore, although the number of welding locations is two, upper and lower, in the embodiment, there is no problem in increasing the number of welding locations.

As described above, the present invention converges a plurality of exhaust pipes connected to an internal combustion engine into a box-shaped expansion chamber made of sheet metal, and exhausts from the exhaust side of the expansion chamber to the atmosphere side via another exhaust pipe. In the desired exhaust system, inserting the plurality of exhaust pipes deep into the expansion chamber,
Since the outer wall of the insertion part of the exhaust pipe and the inner wall of the expansion chamber are fixed by welding, the insertion part of the exhaust pipe acts as a strength member of the expansion chamber, and in order to improve the rigidity of the sheet metal expansion chamber, the exhaust pulsation This prevents the expansion chamber from vibrating and producing loud cries. Furthermore, unlike the conventional structure in which glass wool is pasted, there is no increase in weight, and it can be manufactured at low cost. Furthermore, unlike the case where struts are provided, there is no flow resistance to the exhaust gas, so there is no reduction in engine output.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an exhaust system according to an embodiment of the present invention for a motorcycle equipped with a four-cylinder engine, FIG. 2 is a plan view of an expansion chamber portion of the same exhaust system, and FIG. FIG. 4 is a sectional view taken along the - arrow in FIG. 3. 1, 3... Exhaust pipe, 2... Expansion chamber, 5... Differential user pipe (exhaust pipe), 7... Welded part.

Claims (1)

[Claims] 1. An exhaust system in which a plurality of exhaust pipes connected to an internal combustion engine are converged into a box-shaped expansion chamber made of sheet metal, and the exhaust is discharged from the exhaust side of the expansion chamber to the atmosphere through another exhaust pipe, An exhaust system for an internal combustion engine, characterized in that the plurality of exhaust pipes are deeply inserted into the expansion chamber, and the outer wall of the insertion portion of the exhaust pipes and the inner wall of the expansion chamber are fixed by welding.