JP2819216B2 - Exhaust manifold and manufacturing method thereof - 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 a multi-cylinder engine .
It relates to a sheet metal exhaust manifold to be attached to a port .

[0002]

2. Description of the Related Art When the exhaust manifold is made of sheet metal, it has the advantages that the weight and heat capacity are reduced as compared with those made of cast iron, whereby the running distance of the vehicle is improved and the temperature of the exhaust purification catalyst rises faster. As this kind, there are known techniques such as Japanese Patent Publication No. 63-26254 and Japanese Utility Model Laid-Open Publication No. 1-119824, which press work a sheet metal to separate a half-cylindrical portion and a half-piece having a flat flange. And the flanges are welded by joining the halves together on the palms to form a manifold and an assembly.

In the above-mentioned prior art, flanges are provided on both sides of the exhaust manifold and on both sides of each exhaust passage in various parts, and the flanges are overlapped and welded. Larger and larger heat capacity tends to increase the welding cost, and the portion where thermal distortion occurs due to the difference in thickness between the welded portion and the non-welded portion increases.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet metal exhaust manifold having a weld length as short as possible and a means for easily forming the exhaust passage even if it is bent three-dimensionally. Make it an issue.

[0005]

According to a first aspect of the present invention, there is provided an exhaust manifold having a megaphone shape having a large opening at one end and a small opening at the other end . A large-sized side of a hollow body formed from one sheet metal is provided with a plurality of exhaust passages which are defined by joining opposed flanges extending in the exhaust flow direction, and the small-sized side is an exhaust collecting portion. I do. According to a second aspect of the present invention, a megaphone-shaped hollow body having a large opening at one end and a small opening at the other end is formed from one sheet metal. A second step of forming, in the large-sized portion, a plurality of semi-cylindrical portions extending in the exhaust flow direction and bulging outward, and flanges connecting adjacent semi-cylindrical portions to face each other, And a third step of welding the opposed flanges to each other.

[0006]

According to the first aspect of the present invention, it is possible to eliminate the flange and the welded portion on one or both side surfaces of the exhaust manifold, so that the heat capacity is small, the temperature of the exhaust gas is hardly reduced, and the thermal distortion caused by the welded portion is eliminated. Also less. According to the second aspect of the present invention, a three-dimensionally curved exhaust passage and a flange are formed in the large-sized hollow portion formed in the first step in the second step, and the opposed flanges are formed in the third step. Welding results in an exhaust manifold having a plurality of exhaust passages on the inlet side.

[0007]

An embodiment will be described below with reference to the drawings. In the first embodiment shown in FIGS. 1 and 2, 1 is an exhaust pipe device, 2 is an exhaust manifold, 3 is an inlet flange connected to an engine, and 4 is an outlet flange connected to a catalyst case.
The exhaust manifold 2 includes an inlet-side manifold portion 5 and an outlet-side gathering portion 6. The manifold portion 5 includes four exhaust passages 5a, 5b, 5c, and 5d extending in a finger shape. 5
A substantially U-shaped flange 7 as viewed from the front is provided at the crotch portion d. A mounting hole 3a for an engine is formed in the inlet side flange 3, and a bolt 4a for mounting a catalyst case is fixed to the outlet side flange 4.

The exhaust manifold 2 in the second embodiment shown in FIG. 3 is provided with a web-like flange 8 in the middle of the exhaust passages 5a to 5d of the manifold 5, in which the mounting holes 3 are provided.
The third embodiment differs from the first embodiment in that a lightweight hole 9 concentric with a is provided, but is otherwise the same as the first embodiment.

Next, a method of manufacturing the exhaust manifold 1 or 8 will be described with reference to FIGS. FIG. 4 shows an example of such a case, in which a mild steel plate or a stainless steel plate is used to form a circular material 1 shown in FIG.
In the first step, the material 10 is deep-drawn and the center is cut off to form a megaphone-shaped hollow body 11 having a large portion 12 and a small portion 13 shown in FIG. I do.

Next, as a second step, a multi-part 5 is formed on the large-sized part 12 by a press device 14 as shown in FIG.
The press device 14 includes upper and lower molds 1 having four semicircular grooves.
5a, 15b and cores 16a, 16 to fit in the semicircular grooves
b, 16c, 16d, and the shape of the groove and the core has a three-dimensional shape having a plan view shape close to FIG. 1 and a side view shape close to FIG. A rough processing die and a core for gentle processing, and a finishing die and a core for squaring are used.

FIG. 4C shows the megaphone-shaped hollow body.
11 shows a rough machining state of the multi-part 5 with respect to the large part 12.
Semi-cylindrical portion 5a on the halves 12a side of the _{1 ~5d 1} and the other half portion 12b side semicylindrical portion 5a ₂ with flange 8 is roughing
５5d ₂ and the flange 8 are roughed. Next, the diverging part 5 was formed into a predetermined shape as shown in FIG. 4 (d) by using a finishing die, and simple welding was performed as necessary so that there was no vertical displacement. Thereafter, the flange 8 is punched in a tongue shape as shown in FIG. 4E to leave the U-shaped flange 7, or a light hole 9 is punched in the center of the flange 8 as shown in FIG. .

In the last third step, the halves 12a and 12b are hermetically welded to the outer end of the flange 7 or 8 and the inner periphery of the lightweight hole 9 by airtight welding.

Next, FIG. 6 shows a part of the third embodiment. As a first step, a sector-shaped plate 20 shown in FIG. 6A is cut out from a sheet metal and both ends are welded by welding portions 21 to form a megaphone-shaped hollow. Body 2
Make 2. Then, after the second step, FIGS.
(E) or (c) Forming in the same process as (d) and (f), and moving to the welding process.

Next, FIG. 7 shows a fourth embodiment. In this embodiment, as shown in FIG. 7A, a sector plate 25 having a pair of side flanges 26 is cut out from a sheet metal, and Dimension 2
7 is formed and expanded at a large enlargement ratio, and a hollow body 28 having a substantially U-shaped cross section in which both flanges 26 and 26 are close to each other but not welded is formed, and this is a first step.

Next, as shown in FIGS. 7 (c) and 7 (d), a second step for forming the divergent portion 5 in the large portion 27 is shown in FIG. 4 (c).
After forming the U-shaped flange 7 by the same means as in (e), the U-shaped flange 7 and the side flange 26 are respectively welded by the welding operation in the third step.

In each of the above embodiments, the cross-sectional shape of the hollow body may be any of the various shapes shown in FIG. FIG. 8A shows the case of the seamless hollow body 11 shown in the first embodiment, and FIG. 8B shows the result of butt welding performed on the hollow body 22 of the third embodiment of FIG. is there. FIG.
(D) is applied to the hollow body 28 in FIG. 7, and the lower flange of the upper and lower flanges 26 is longer, which is convenient for forming the welded portion 21. FIG. 8 (c)
Shows an example of the lap welding portion 29. And FIG. 8 (b)
The welding structures (c) and (d) can be appropriately adopted in each embodiment.

As described above, in FIG. 8A, there is no welding portion on the side portion, and in FIGS. 8B to 8D, only one welding portion 21 is provided on the side portion. It requires less and does not interfere with the forming process of the multiplicity part 5.

[0018]

According to the first aspect of the present invention, since the sheet metal is used, the thickness of the exhaust manifold can be reduced to the minimum necessary, and there is no weld at the long side.
Even if there is only one, it is lightweight and can reduce the heat capacity. Thus by using the engine using the exhaust manifold for a vehicle, the advantage of with improvement in fuel consumption savings are expected, less reduction of the exhaust temperature is at engine start, it can be started immediately purifying effect temperature rise faster in the exhaust gas purifying catalyst Having.

According to the second aspect of the present invention, the two halves of the hollow body can be formed at the same time, and can be formed even if the exhaust passage is bent three-dimensionally. It has the advantages that the number of molds is small and welding is small, and that an exhaust manifold having an ideal shape can be obtained. Ma
In addition, required for the conventional process,
The process of positioning and welding the long sides
There are advantages that can be omitted.

[Brief description of the drawings]

FIG. 1 is a front view of a first embodiment of an exhaust manifold.

FIG. 2 is a side view of the same.

FIG. 3 is a front view of a second embodiment.

FIG. 4 is an explanatory view of a manufacturing process of the first embodiment.

FIG. 5 is a longitudinal sectional view of a mold.

FIG. 6 is an explanatory view of a first step of the third embodiment.

FIG. 7 is a process explanatory view of the fourth embodiment.

FIG. 8 is a sectional view of a hollow body.

[Explanation of symbols]

2 Exhaust manifold 5 Miscellaneous parts 5a, 5b, 5c, 5d Inlet-side exhaust passage
6 Assembling part 7, 8, 26 Flange 11, 22, 28 Hollow body 12 Large part 12a, 12b Half part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 7/18 B21D 53/84 F01N 7/10 B23K 9/00 501 F16L 41/03

Claims (2)

(57) [Claims] 1. A megaphone type having a large opening at one end and a small opening at the other end, and opposed flanges extending in a direction of exhaust gas flow on a large side of a hollow body formed of one sheet metal. An exhaust manifold, wherein a plurality of exhaust passages are provided by joining the exhaust manifolds, and an exhaust manifold is provided on a small side. 2. A first step in which a megaphone-shaped hollow body having a large opening at one end and a small opening at the other end is formed from a single sheet metal; A second step of forming a plurality of semi-cylindrical portions extending in the direction and bulging outward, and a flange connecting adjacent half-cylindrical portions to face each other; a third step of welding the facing flanges to each other; A method for manufacturing an exhaust manifold, comprising: