JP3388726B2 - Two-passage exhaust pipe and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-cylinder engine in which the exhaust pipe has two passages partitioned by partition walls in order to prevent the exhaust gases emitted from different exhaust ports from interfering with each other. The present invention relates to a two-pass exhaust pipe that has a shape of pipe and that allows exhaust gas to flow through each passage alternately.

[0002]

2. Description of the Related Art As a θ-type exhaust pipe, one formed of one or two plates is known, and an exhaust pipe of a type using one plate has a structure shown in FIG. 4, for example. It is provided (JP-A-9-192727). In the figure, a is an exhaust pipe, b is a heat shield pipe, and the exhaust pipe a is a flange formed by bending a semicircular peripheral wall portion a2 from both sides of the partition wall portion a1 at a substantially right angle and connecting it to the tip of the peripheral wall portion a2. A3 is applied to the bent portion and welded to form a welded portion a4.
, C2 are formed. The exhaust pipe a has a shape in which the partition wall portion a1 and the peripheral wall portion a2 are bent at a substantially right angle. Therefore, when the wall portion vibrates flexibly by the pressure of exhaust gas that alternately passes through the passages c1 and c2, the bent portion is bent. Repeated stress concentrates on and fatigue is likely to occur.

Further, in the bent portion between the partition wall portion and the peripheral wall portion,
A curve having a small radius of curvature, that is, a curve having an R is also known (Japanese Patent Laid-Open No. 11-294154), but since a small valley formed by two Rs is filled with a weld bead, a stress relaxation effect by R is exerted. Is reduced and stress tends to concentrate near the weld. Further, when a thin plate is used as the material, the plate is easily melted during welding and holes are likely to be formed.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a two-passage exhaust pipe which can prevent stress from concentrating on a part of the pipe wall, requires a small amount of heat input during welding, and does not cause perforation. The challenge is to find a way.

[0005]

Means for solving the above-mentioned problems are as described in each claim, and the two-passage exhaust pipe according to claim 1 has one metal plate having a substantially S-shape. Peripheral wall portions are formed on both sides of the partition wall portion, and at the end portions of both peripheral wall portion portions, a valley portion wall located inside the inner virtual line of the peripheral wall portion portion is formed, and at the end portion of the valley portion wall portion, the valley portion portion is formed. It is characterized in that an outward flange having a shape along the valley wall facing the wall is formed and the flange is joined to the valley wall to form the valley. According to this means, since the partition wall portion and the peripheral wall portion are not bent in a square shape, bending stress is not concentrated even if the wall vibrates due to pulsation of exhaust gas.

According to a second aspect of the present invention, there is provided a two-passage exhaust pipe according to the first aspect, in which a front end portion of the flange and a facing wall portion are welded to each other. According to this means, the amount of heat input is small because the amount of welding is small.

A two-passage exhaust pipe according to a third aspect of the present invention is characterized in that, in the first or second aspect, a flange portion is first bent at both ends of one metal plate, and a partition wall portion, a peripheral wall portion and a valley wall are formed on the metal plate. It is characterized by being formed. According to this means, the flange can be easily formed, deformation of the plate end portion is suppressed in the subsequent steps, and welding is stabilized.

The two-passage exhaust pipe of claim 4 is the same as in claim 1,
Or 3, a part of the valley wall is formed by a flat surface to form a V-shaped valley, and the flange is formed so as to extend substantially parallel to the opposing valley wall. . According to this means, the flanges are provided along the opposing valley walls, so that the joining can be facilitated.

In the method for manufacturing a two-passage pipe according to a fifth aspect of the present invention, one metal plate is formed into a substantially S-shape to form peripheral wall portions on both sides of the partition wall portion, and at both ends of the peripheral wall portion, virtual inner walls of the peripheral wall portion are formed. While forming a valley wall located inside the line, at the end of the valley wall, an outward flange is formed along the valley wall facing the valley wall, and with the tip portion of the flange. The opposing valley walls are welded together.

According to this means, since the tip of the thin flange can be welded to the opposing wall portion, the amount of heat input can be small and the welding torch can be inserted shallowly for welding. Can manufacture tubes.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a state before welding of the two-passage exhaust pipe 1, using one steel plate having a length equal to or more than one exhaust pipe as a raw material, and bending portions 3a on both sides of a width W portion which becomes the partition wall portion 2. As shown, the flat and inclined base valley wall 3 is bent at a slight inclination angle, and the semicircular peripheral wall portion 5 is bent through the curved portion 4.
Is curved, and through the curved portion 6 having the same curvature as the curved portion 4,
The flat and sloped end valley wall 7 is bent, and the width f
The short flange 8 is folded back.

The base valley wall 3 can be said to be a facing wall portion facing the end valley wall 7, and the partition wall portion 2 may be formed as an extended flat surface.

The flange 8 is provided for welding and is formed substantially parallel to the opposing base valley wall 3 and may be separated from the base valley wall 3 at the time of molding, but at the time of welding. The jig is pressed from the peripheral wall portion 5 side by a jig and held so that at least the tip of the flange 8 can be brought into close contact with the base valley wall 3.

FIG. 2 shows the welding method. The molded product is held by a jig to bring the valley wall 3 and the flange 8 into close contact with each other, and the welding torch 10 is inserted between the two valley walls 3 and 7. By blowing an arc to the tip of the flange 8, a weld bead 11 is formed between the tip and the valley wall 3 of the base, welding is performed, and if welding of one flange 8 is completed, the molded product is inverted. Then, the other flange 8 is welded to form V-shaped troughs 9 and 9 having a depth h, and exhaust passages 12 and 13 having a substantially semicircular shape. Since it is sufficient to weld the upper end of the flange 8 at the time of welding, it is not necessary to insert the welding torch 10 deep into the valley portion 9, and welding can be performed even if the valley portion 9 that becomes a waste space is narrow. Further, by making the valley wall 3 a flat surface, it is easy to bring the flange 8 into close contact. The width f of the flange 8 may be wider or narrower than that shown in the figure.

The material steel plate has a thickness of 0.6 mm and 0.8 m.
Even thin plates such as m, 1.0 mm, and 1.2 mm can be welded. At the time of welding, the amount of heat that melts the end of the thin flange 8 and the narrow part of the surface of the valley wall 3 is consumed. Therefore, TIG welding or MIG welding, which has a low heat input and a low welding cost, can be used as the welding means.

The two-passage exhaust pipe 1 of the present invention has the above-mentioned structure, and since the width W of the partition wall portion 2 is considerably smaller than the diameter D or the height H of the exhaust pipe, the total pressure of the exhaust gas applied to the partition wall portion 2 is It is small and the bending force applied to the bend 3a is also small. Since the bent portion 3a is bent at an obtuse angle close to a flat surface, it has a buffering property and less stress concentration. Further, since the end valley wall 7 is welded in a bridge shape to the middle portion of the base valley wall 3 by the flange 8, the stress applied to one valley wall is dispersed to the other valley wall. Therefore, the exhaust passages 12, 1
Even if a bending load is applied oscillatingly from the exhaust gas that passes through the inside of 3 alternately in a pulsating manner, stress concentration is low and fatigue is low.

[0017]

As is apparent from the above description, according to the means of claim 1, since the width of the partition wall is smaller than the pipe diameter, the total pressure acting from the exhaust gas is small and the partition wall due to the pressure of the exhaust gas is small. Bending of the part can be suppressed to a minimum. In addition, since the bending angle of the bent portion is small and the flange straddles the trough walls on both sides, the force acting on one trough wall is dispersed to the other trough wall, and stress is applied to the bent and welded portions. Is suppressed and fatigue is prevented even after long-term use.

According to the second aspect of the present invention, since it is sufficient to weld the tip of the flange, the amount of heat input is small, and there is an effect that no hole is formed.

According to the third aspect of the present invention, if the flange is molded first, the rigidity of this portion becomes high and the deformation in the subsequent molding process is small, resulting in the flatness of the flange portion. There is an effect that it can be improved and stable welding can be performed.

According to the means of the fourth aspect, since the opposing wall facing the valley wall is a flat surface, there is an effect that the flanges can be joined together or welded and positioned easily for welding.

According to the means of claim 5, since the tip of the thin flange can be welded to the wall of the valley portion, the amount of heat input can be small and the welding torch can be inserted shallowly for welding. The effect is that a wide exhaust pipe can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of a two-passage exhaust pipe of the present invention before welding.

FIG. 2 is a sectional view showing welding work.

[Figure 3] Cross-sectional view of the product after welding

FIG. 4 is a sectional view of a conventional example.

[Explanation of symbols]

1 2 passage exhaust pipe 2 partition wall 3, 7
Valley wall 4, 6 Curved part 8 Flange
9 Valley 10 Welding torch

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroto Yanagibayashi Inventor Hiroto Yagibayashi 1 508 Toyocho Hamamatsu City, Shizuoka Prefecture Yutaka Giken (72) Inventor Kiyuki Sato 1 508 Toyocho Hamamatsu City, Shizuoka Prefecture Company Yutaka Giken (72) Inventor Kazuo Ishii 1-4-1 Chuo, Wako-shi, Saitama Prefectural Technology Research Institute (72) Inventor Takeshi Somura 4-1-1 Chuo, Wako-shi, Saitama Stock Company Honda Inside the Technical Research Institute (72) Inventor Masayuki Uekane 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. Within the Technical Research Institute of Honda (72) Inventor Yoshihiko Eguchi 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. In the laboratory (56) Reference JP-A-11-294154 (JP, A) JP-A-2000-34921 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01N 7/18 B21D 53 / 84

Claims (5)

(57) [Claims] 1. A metal plate having a substantially S-shape is formed with peripheral wall portions on both sides of a partition wall portion, and a trough wall positioned inside an inner virtual line of the peripheral wall portion is formed at both ends of the peripheral wall portions. As it forms
At the end of the trough wall, an outward flange having a shape along the trough wall opposite to the trough wall is formed, and the trough is formed by joining the flange to the trough wall. And a two-pass exhaust pipe. 2. The two-passage exhaust pipe according to claim 1, wherein a front end portion of the flange and a facing wall portion are welded to each other. 3. A metal plate according to claim 1, wherein flange portions are first bent at both ends of one metal plate, and partition walls, peripheral wall portions and valley walls are formed on the metal plate. Passage exhaust pipe. 4. The method according to claim 1, 2 or 3, wherein a part of the trough wall is formed by a plane to form a V-shaped trough, and the flange extends substantially parallel to the opposing trough wall. A two-passage exhaust pipe characterized in that it is formed to have 5. A metal plate having a substantially S shape is formed with peripheral wall portions on both sides of the partition wall portion, and a valley wall located inside an inner imaginary line of the peripheral wall portion is formed at both ends of the peripheral wall portions. As it forms
An outer flange is formed along the valley wall facing the valley wall at the end of the valley wall, and the tip portion of the flange is welded to the facing valley wall. Manufacturing method of two-pass exhaust pipe.