JP2004183583A - Exhaust pipe structure for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide exhaust pipe structure for an engine reduced in number of parts and welding portions to reduce cost. <P>SOLUTION: The structure is provided with: first and second manifolds 2, 3 joined respectively to rear end portions of pairs of exhaust pipes 1A to 1D; and a third manifold 4 joined to rear end portions 2d, 3d of the first and second manifolds 2, 3. The first and second manifolds 2, 3 respectively have front end portions 2c, 3c including pairs of inlet ports 2a, 3a to which the rear end potions of the exhaust pipes 1A to 1D are inserted, and rear end portions 2d, 3d including an outlet port 2b and an outlet port 3b. The third manifold 4 has a front end portion 4c including a pair of inlet ports 4a to which the first and second manifolds 2, 3 are inserted, and a rear end portion 4d including an outlet port 4b. The first, second, and third manifolds 2, 3, 4 are press-worked articles made from a single pipe material. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine exhaust pipe structure in which a plurality of exhaust pipes respectively connected to a plurality of exhaust ports of a multi-cylinder engine are assembled so as to be connectable to a single muffler.
[0002]
[Prior art]
Normally, an engine has as many exhaust pipes as the number of cylinders, and these exhaust pipes are assembled and connected to a single large-diameter collective pipe. For example, in a motorcycle equipped with a four-cylinder engine, an exhaust pipe structure is known in which the rear ends of each of four exhaust pipes are inserted and connected to an inlet opening of a single manifold (see Patent Document 1). ).
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 1-91027 (pages 7-9, FIGS. 5-7)
[0004]
[Problems to be solved by the invention]
However, the exhaust pipe structure is a collection of four tubes. One side of the outlet opening of each tube is cut out and formed into a sector shape in which a circle is divided into four equal parts. The openings are assembled in a circular arrangement, and each of the two adjacent tube fitting portions is welded to integrate the four tubes. Therefore, since this exhaust pipe structure requires four tubes, the number of parts is increased, and welding locations are also four locations where the rear ends of the four exhaust pipes and the inlets of the four tubes of the manifold are welded. In addition, the number of the three outlet portions gathered together and one location where the rear end portion of the manifold is welded to a single collecting pipe is increased to a total of eight locations, which increases the cost.
[0005]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an engine exhaust pipe structure with a reduced number of parts and joints.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an exhaust pipe structure for an engine according to the present invention includes a first manifold joined to a rear end portion of a pair of exhaust pipes, and a rear end portion of another pair of exhaust pipes. A second manifold joined, and a third manifold joined to rear ends of the first and second manifolds, the first and second manifolds comprising rear ends of the exhaust pipes Having a front end having a pair of inlet openings and a rear end having a single outlet opening, the third manifold is a pair of the first and second manifolds being inserted The first to third manifolds have a front end portion having an inlet opening and a rear end portion having a single outlet opening, and are pressed products of a single pipe material.
[0007]
According to the exhaust pipe structure of the engine, the first and second manifolds respectively connected to the rear end portions of the pair of exhaust pipes are integrally formed products obtained by pressing a single pipe material. Both the number of points and joints are reduced, and the cost can be reduced accordingly. In addition, since the first and second manifolds are pressed products of a single pipe material, the pipe length is shortened by gradually changing the cross-sectional area of the internal passage from the inlet opening to the outlet opening. However, the exhaust gas can flow smoothly. As a result, the pipe lengths of the first and second manifolds can be shortened to reduce the overall size, so that restrictions on mounting on the vehicle body are alleviated and the degree of freedom of installation location is increased.
[0008]
In a preferred embodiment of the present invention, the first and second manifolds are arranged side by side, and a pair of the inlet openings are arranged in the vertical direction. According to this configuration, since the gap between the first and second manifolds cannot be seen from the side, the appearance of a vehicle such as a motorcycle in which the exhaust pipe structure is mounted in an exposed form is improved.
[0009]
In a preferred embodiment of the present invention, further, at least one of the first to third manifolds is divided into a passage in the manifold, and a pair of partition passages from each of the inlet openings to the single outlet opening is provided. A partition plate to be formed is provided. According to this configuration, the exhaust gas can flow smoothly because the partition plate prevents the exhaust gas from flowing backward due to the difference in the exhaust timing of each cylinder of the engine. However, the engine output can be improved.
[0010]
In a preferred embodiment of the present invention, each inlet opening of the manifold provided with the partition plate is missing a part of an arc when viewed from the upstream side of the exhaust gas flow, and a pair of inlet openings is formed at the missing portion. An S-shaped partition plate is disposed so as to fill at least a part of the missing portion, and both end portions thereof are respectively joined to inner surfaces forming one and the other partition passages in the manifold. Yes. According to this configuration, a pair of partition passages having the same passage area can be easily formed inside the manifold by one partition plate. The partition plate also has a function of reinforcing the manifold.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIGS. 1A and 1B are a plan view and a side view showing an exhaust pipe structure of a motorcycle according to an embodiment of the present invention. This exhaust pipe structure includes a first manifold 2 connected to a rear end portion (right end portion in the figure) of a pair of left exhaust pipes 1A and 1B shown in FIG. The second manifold 3 connected to the rear ends of the exhaust pipes 1C and 1D, and the third manifold 4 connected to the rear ends of the first and second manifolds 2 and 3 are provided. The front end portions of the exhaust pipes 1A to 1D are connected to the exhaust ports of the engine E shown in FIG. 1B supported by a vehicle body frame (not shown), and exhaust gas G from the engine E is led out. The rear end of the third manifold 4 is connected to a muffler (not shown) via a collective connection pipe 7.
[0012]
As shown in FIG. 2, each of the first and second manifolds 2 and 3 has a front end 2c having a pair of inlet openings 2a and 3a having a diameter into which the rear ends of the exhaust pipes 1A to 1D are fitted. It is formed in the same shape having 3c and rear end portions 2d and 3d having single circular outlet openings 2b and 3b. The first and second manifolds 1 and 3 are integrally molded products obtained by press-working a single circular pipe material.
[0013]
The pair of inlet openings 2a and 3a has a gourd shape, that is, a part of a circle having an inner diameter into which the exhaust pipes 1A to 1D are inserted as viewed from the upstream side of the flow of the exhaust gas G. 30 are in communication with each other. On the outside of the portion where the two arcs, which are the missing portions 20 and 30, overlap, are recessed portions 2e and 3e. The outlet openings 2b and 3b are circular as described above. Accordingly, each manifold 2 and 3 is narrowed so that the passage area gradually decreases from the front end (upstream end) to the rear end (downstream end).
[0014]
The third manifold 4 has the same shape as the first and second manifolds 2 and 3, and a front end portion 4c having a pair of inlet openings 4a into which both the manifolds 2 and 3 are fitted. And a rear end 4d having a single outlet opening 4b. The pair of inlet openings 4a and 4a are also gourd-shaped, and a part of a circle having an inner diameter into which the rear end portions 2d and 3d of the first and second manifolds 2 and 3 are fitted is missing. The shapes are in communication with each other, and a recess 4e is formed on the outside. The outlet opening 4b has a circular shape having a diameter into which the collecting pipe 7 is fitted. The third manifold 4 is also narrowed so that the passage area gradually decreases from the front end (upstream end) toward the rear end (downstream end).
[0015]
The rear ends of the exhaust pipes 1A to 1D are fitted into the front ends 2c and 3c from the pair of inlet openings 2a and 3a of the first and second manifolds 2 and 3, respectively. Between the opening edge and the outer peripheral surfaces of the exhaust pipes 1A to 1D, bead welding is performed as shown in FIG. 3 is connected. The rear end portions 2d and 3d of the first and second manifolds 2 and 3 are fitted into the front end portion 4c from a pair of inlet openings 4a of the third manifold 4, and the opening edges of the inlet openings 4 and the respective manifolds Between the outer peripheral surfaces of the second and third rear end portions 2d and 3d, bead welding is performed, and the welded portion 9 is connected to the third manifold 4. Similarly, the rear end portion 4 c of the third manifold 4 is connected to the collecting pipe 7 by a bead weld portion 10.
[0016]
As clearly shown in FIG. 5, in this exhaust pipe structure, the first and second muholds 2 and 3 are arranged side by side, and a pair of inlet openings 2a and 3a are arranged in the vertical direction. The gap 22 between the first and second manifolds 2 and 3 is not visible from the side. Therefore, the exterior of the vehicle is improved particularly when the exhaust pipe structure is mounted on a motorcycle that is exposed to the outside.
[0017]
A partition plate 11 is provided inside the first and second manifolds 2 and 3. The partition plate 11 includes a linear partition portion 11a that divides the manifolds 2 and 3 into a pair of partition passages 12A, 12B, 13A, and 13B, and both ends of the partition portion 11a in opposite directions. It has an S shape having both ends 11b and 11c extending in a curved manner along the inner surfaces of the manifolds 2 and 3. Further, as shown in FIG. 4, the partition plate 11 extends from the vicinity of the lower end side of the inlet openings 2a and 3a to the vicinity of the upstream side of the outlet openings 2b and 3b.
[0018]
In the pair of partition plates 11, the central partition portion 11 a shown in FIG. 5 is in the missing portions 20 and 30 between the pair of inlet openings 2 a and 3 a of the first and second manifolds 2 and 3. It arrange | positions so that most parts except a front-end part may be filled, and both ends 11b and 11c are joined to the inner surface which forms one division channel | path 12A, 13A and the other division channel | path 12B, 13B in each manifold 2,3. ing. The front edge of the partition plate 11 may be matched with the front edge of the inlet openings 2a and 3a, and the whole of the missing portions 20 and 30 may be filled with the partition plate 11.
[0019]
Each partition plate 11 is welded to the manifolds 2 and 3 at the welded portion 24 at the front edge shown in FIG. Thereby, each partition plate 11 divides the internal passages of the first and second manifolds 2 and 3 into two at the partitioning portion 11a so as to face the pair of inlet openings 2a and 3a. A pair of partition passages 12A, 12B, 13A, 13B extending from 3a to a single outlet opening 2b, 3b is formed. The two partition passages 12A and 12B of the first manifold 2 have the same passage area, face the outlet openings of the exhaust pipes 1A and 1B, and the two partition passages 13A and 13B of the second manifold 3 Also have the same passage area and face the outlet openings of the exhaust pipes 1C and 1D.
[0020]
Moreover, as shown in FIG. 4, the partition plate 11 is formed with a semicircular cutout 11d at the rear end portion of the partition portion 11a. Thereby, the partition plate 11 can suppress that the large oscillating pressure and heat load of exhaust gas act on the rear-end part which is a confluence | merging location of the exhaust gas which has flowed through the two division channel | paths 12 and 13. FIG.
[0021]
In the exhaust pipe structure having the above-described configuration, a pair of exhaust pipes 1A to 1D are connected to the first and second manifolds 2 and 3 of the integrally molded product, and the manifolds 2 and 3 are connected to the third manifold of the integrally molded product. 4 compared to the conventional manifold that combines four pipes, the number of parts is reduced from four to three, and the number of welded parts is changed from the conventional eight to two welded parts 8, 8, One weld 9 and one weld 10 are reduced to a total of four locations. Therefore, with this exhaust pipe structure, the cost can be reduced as the number of parts and man-hours are reduced.
[0022]
Further, since the first to third manifolds 2 and 3 are press-processed products made of a single pipe material, as is apparent from FIG. 3 (side view) and FIG. By reducing the pipe length, the exhaust gas G can flow smoothly even if the pipe length is shortened, so the overall shape is downsized and the restrictions on mounting on the vehicle body are reduced. The degree of freedom increases.
[0023]
Further, the partition plate 11 prevents a back flow of exhaust gas caused by different exhaust timings of the cylinders of the engine E (FIG. 1B), and a pair of partition passages formed by the partition plate 11. Since 12A, 12B, 13A, and 13B are provided so as to be opposed to the outlet openings of the exhaust pipes 1A to 1D on the upstream side in the flow direction of the exhaust gas, the exhaust gas can flow smoothly. The partition plate 11 also has a function of reinforcing the first and second manifolds 2 and 3.
[0024]
The third manifold 4 may be provided with a partition plate to have the same structure as the first and second manifolds 2 and 3.
[0025]
【The invention's effect】
As described above, according to the exhaust pipe structure of the engine of the present invention, each of the first to third manifolds is an integrally molded product obtained by pressing a single pipe material. Both can be reduced, and cost reduction by this can be aimed at.
[Brief description of the drawings]
FIGS. 1A and 1B are a plan view and a side view showing an exhaust pipe structure according to an embodiment of the present invention.
FIG. 2 is a perspective view showing the exhaust pipe structure of the above.
FIG. 3 is a side view of the main part shown by cutting the upper half.
4 is a horizontal sectional view taken along line IV-IV in FIG.
5 is a front view seen from the direction P of FIG. 3. FIG.
[Explanation of symbols]
1A to 1D ... exhaust pipe 2 ... first manifold 2a, 2b ... inlet opening, outlet opening 2c, 2d ... front end, rear end 3 ... second manifold 3a, 3b ... inlet opening, outlet opening 3c, 3d ... Front end portion, rear end portion 4 ... third manifold 4a ... inlet opening, outlet openings 4c, 4d ... front end portion, rear end portion 11 ... partition plates 12A, 12B, 13A, 13B ... partition passage

Claims (4)

A first manifold joined to the rear ends of the pair of exhaust pipes; a second manifold joined to the rear ends of the other pair of exhaust pipes; and the rear of the first and second manifolds A third manifold joined to the end,
The first and second manifolds have a front end having a pair of inlet openings into which a rear end of the exhaust pipe is inserted and a rear end having a single outlet opening;
The third manifold has a front end having a pair of inlet openings into which the first and second manifolds are inserted and a rear end having a single outlet opening;
The first to third manifolds are engine exhaust pipe structures that are pressed products of a single pipe material. The engine exhaust pipe structure according to claim 1, wherein the first and second manifolds are arranged side by side and a pair of the inlet openings are arranged in the vertical direction. 3. The pair of partition passages according to claim 1 or 2, further comprising: at least one of the first to third manifolds partitioning the passages in the manifolds and extending from each of the inlet openings to the single outlet opening. An engine exhaust pipe structure including a partition plate to be formed. 4. A shape according to claim 3, wherein each of the inlet openings of the manifold provided with the partition plate is missing a part of an arc when viewed from the upstream side of the exhaust gas flow, and a pair of inlet openings communicates with each other. An S-shaped partition plate is disposed so as to fill at least a part of the missing portion, and both ends of the partition plate are respectively joined to inner surfaces forming one and the other partition passages in the manifold. Exhaust pipe structure.

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