JPH07197815A - Manufacture of exhaust manifold for automobile - Google Patents

Abstract

PURPOSE:To eliminate wasteful space by providing a plurality of annular projecting parts on the wall surface of a metallic pipe in the same direction in an integrated manner to form a joined pipe part, bending the tip part of the metallic pipe at the prescribed bending angle in the same direction as that of the annular projecting parts, and fixing a flange to an end part of each joined pipe part. CONSTITUTION:In a metallic pipe 10, the wall surface is annularly projected at two parts in the same direction from the same surface by. e.g. the bulging corresponding to an exhaust port of the cylinder head of the engine to form joined pipe parts 1 1, 12. The tip part 13 of the metallic pipe 10 is bent with the bending angle of <=0.7 times the diameter of the metallic pipe 10 on the center line of the metallic pipe 10 in the same direction as that of the respective joined pipe parts 11, 12 to form a joined pipe part 14. The prescribed clearance is secured between the engine and the exhaust manifold by setting the bending angle to <=0.7 times the diameter, and realizing almost the same height when flanges 15, 116, 7 are fixed to the tip of the respective joined pipe parts 11, 12, 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an exhaust manifold using a metal pipe attached to an internal combustion engine for automobiles.

[0002]

2. Description of the Related Art Conventionally, an exhaust manifold of this type is known from, for example, Japanese Utility Model Publication No. 59-43460. This will be described with reference to FIG. In the figure, reference numeral 1 is an exhaust manifold, which is integrally provided with a coupling pipe 2 which is coupled to a cylinder head of an engine via a flange 3 separately. Further, the exhaust pipe on the downstream side is connected via the flange 4.

However, since the exhaust manifold 1 is formed by casting, its thickness becomes thick and heavy, and since its heat capacity is large, it absorbs heat from the exhaust gas and reduces the activity of the converter provided on the downstream side. There is a problem that the manufacturing cost is high.

Therefore, for example, Japanese Patent Laid-Open No. 62-20621.
As disclosed in Japanese Patent Publication No. 6 and the like, a pipe using a metal pipe has been proposed. This will be described with reference to FIG.
In the figure, reference numeral 5 is a metal pipe, and a coupling pipe 6 is formed by bulging on the same surface of the wall surface. One flange 7 is fixed to each coupling pipe 6 by welding.

[0005]

However, since the exhaust manifold 9 using the metal pipe 5 is provided with the connecting pipe 6 on the same surface of the wall surface, the tip portion 8 should be closed before use. I had no choice. Therefore, there is a problem that productivity is deteriorated when a wasteful space portion is formed between the most advanced coupling pipe 6 and the tip portion 8. In addition, this extra space may hinder the flow of exhaust gas.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to bend the front end portion of a metal pipe to secure a distance between the flange and the coupling pipe, and to waste. It is an object of the present invention to provide a method for manufacturing an exhaust manifold for an automobile, which can eliminate a large space and has good productivity.

[0007]

In the method of manufacturing an exhaust manifold for an automobile according to the present invention, a coupling pipe attached to each exhaust port of a cylinder head of an internal combustion engine for an automobile through a gasket is assembled into one pipe. In the method for manufacturing an exhaust manifold, a plurality of annular protrusions are integrally provided on the wall surface of the metal pipe in the same direction to form a coupling pipe portion, and the tip end of the metal pipe is formed into the annular protrusion. In the same way as the above, on the center line of this metal pipe, bend it at a bending angle of 0.7 times or less of its diameter to make a connecting pipe part, and then weld each connecting pipe part of this metal pipe separately. By fixing the flanges, the heights of the flanges fixed to the ends of the coupling pipe portions are made substantially the same.

[0008]

In the present invention, first, the connecting portion is formed on the wall surface and the tip of the metal pipe as follows. That is,
On the wall surface of the metal pipe, a plurality of annular protrusions are integrally provided in the same direction to form a coupling pipe portion. And
At the tip of the metal pipe, the connecting pipe is formed by bending it on the center line of the metal pipe on the center line of the metal pipe at a bending angle of not more than 0.7 times its diameter.

Next, the flanges are individually fixed to the connecting pipe portions of the metal pipe by welding. by this,
It is possible to make the heights of the flanges fixed to the end portions of the coupling pipe portions substantially the same. In the exhaust manifold for an automobile formed in this way, the connecting pipe formed at the tip and the metal pipe communicate with each other without forming a useless space, and the exhaust gas discharged from the engine is discharged from the other connecting pipe. Like the inflowing exhaust gas, it flows through the metal pipe to the downstream side.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an exhaust manifold manufactured by an automobile exhaust manifold manufacturing method according to an embodiment of the present invention, in which reference numeral 10 represents a metal pipe.

The metal pipe 10 is made of stainless steel, and its wall surface is annularly projected from the same surface at two locations in the same direction by, for example, bulging according to the exhaust port of the cylinder head of the engine. Parts 11 and 12
To form.

The tip portion 13 of the metal pipe 10
Bend R on the center line S of the metal pipe 10.
= 0.7D to 1D (here, D represents the diameter of the metal pipe 10) and bent in the same direction as the coupling pipe portions 11 and 12 to form the coupling pipe portion 14 in the same manner.

As described above, when the bending R = 0.7D to 1D, a predetermined space (for example, 30 mm) is secured between the engine and the exhaust manifold 20, and at the same time, the connecting pipe parts 11, 12 and 14 are connected. Flange 15,1 at the tip
When 6 and 17 are fixed by welding, their heights are almost the same. As a result, the assembly to the engine becomes easy.

The bending R has a lower limit of at least 0.7D and an upper limit of 1D for the reasons described above. Here, when the bend R is 0.5D, which is the radius of the metal pipe 10, the metal pipe 10 is crushed and the bent inner pipe wall and the outer pipe wall are brought into close contact with each other, so that the exhaust pipe can play a role. Absent.

Therefore, when bending the metal pipe 10,
Bending R does not hold unless it exceeds 0.5D. Then, when the minimum bend R was taken after substantially ensuring the perfect circle of the metal pipe 10, it became clear that the bend R needs to be 0.7 D or more. In addition, if the distance between the engine and the exhaust manifold 20 is less than about 30 mm, the mounting work becomes difficult, considering the possible mounting work distance.
If it exceeds mm, the occupied space becomes large and wasteful.

Therefore, it is sufficient that the bending R of the metal pipe 10 is at most 1D. However, for example, not an automobile, but an internal combustion engine having a large space for occupying the engine, and when the distance between the engine and the exhaust manifold 20 can be 30 mm or more, the bend R can be 1D or more. . In this case, the height of the coupling pipe parts 11 and 12 formed by burring or the like is as shown in FIG.
Since it becomes lower than the joint pipe portion 14 formed by bending, a straight pipe portion is provided on each flange 15 and 16,
The heights of the flanges 15, 16 and 17 are almost the same.

Further, a flange 18 for connecting to the exhaust system is fixed to the downstream end of the metal pipe 10 by welding. According to the method for manufacturing an automobile exhaust manifold according to this embodiment thus configured, the tip portion 13 of the metal pipe 10 is bent in the same manner as the other coupling pipe portions 11 and 12 to form the coupling pipe portion 14. However, the flanges 15 and 1 are separately provided on these tips so that they are at the same level.
Since 6 and 17 are fixed by welding, there is no risk of height difference during assembling to the engine, the productivity is easy, and the assembling work is also easy.

Further, since the bend is set to R = 0.7D or more, the metal pipe 10 can be bent and the flanges 15, 12 provided at the tips of the coupling pipe parts 11, 12 and 14 are connected.
Distance between 16 and 17 and wall of metal pipe 10 is 30m
It is possible to secure a very small gap of m. Furthermore, the exhaust manifold 20 produced by this method
Since the tip portion 13 is bent in the same direction as the coupling pipe portions 11 and 12 to form the coupling pipe portion 14, the exhaust gas discharged from the exhaust port connected to the coupling pipe portions 11 and 12 is the coupling pipe portion. There is no inconvenience that the exhaust gas stagnates or interferes, unlike the conventional exhaust manifold using a straight metal pipe, which flows down through the metal pipe 10 through 14.

In the above embodiment, the method of manufacturing the exhaust manifold having the three connecting pipe portions has been described.
It goes without saying that the number can be appropriately set according to the engine.

[0020]

As described above, according to the present invention, a plurality of annular projecting portions are integrally provided in the same direction on the wall surface of a metal pipe to form a coupling pipe portion, and the tip end portion of the metal pipe is formed into the above-mentioned annular shape. Bent on the center line of this metal pipe in the same direction as the protruding part at a bending angle of 0.7 times or less of its diameter to form a connecting pipe part, and then weld it to each connecting pipe part of this metal pipe. By separately fixing the flanges with each other, the height of each flange fixed to the end of each coupling pipe part was made almost the same height, so that a wasteful space is secured while securing the distance between the flange and the metal pipe. It is possible to eliminate them, and there is no possibility of height difference during assembling to the engine, which is advantageous in that the production is easy and the assembling work is easy.

[Brief description of drawings]

FIG. 1 is a perspective view showing an exhaust manifold manufactured by an automobile exhaust manifold manufacturing method according to an embodiment of the present invention.

FIG. 2 is a side view of a metal pipe used for the exhaust manifold of FIG.

FIG. 3 is a plan view of a metal pipe used for the exhaust manifold of FIG.

FIG. 4 is a side view showing a conventional cast exhaust manifold.

FIG. 5 is a side view showing an exhaust manifold using a conventional metal pipe.

[Explanation of symbols]

 10 Metal Pipes 11, 12, 14 Coupling Pipe Section 13 Tip of Metal Pipe 10 15 Flange 20 Exhaust Manifold S Center Line of Metal Pipe 10

Claims (1)

[Claims] 1. A method of manufacturing an exhaust manifold in which connecting pipes, which are attached to respective exhaust ports of a cylinder head of an internal combustion engine for automobiles through gaskets, are assembled into one pipe, wherein a plurality of metal pipes are provided on a wall surface of the metal pipe. A ring-shaped protrusion is integrally provided in the same direction to form a coupling pipe portion,
The tip of the metal pipe is bent in the same direction as the annular projection on the center line of the metal pipe at a bending angle of not more than 0.7 times its diameter to form a connecting pipe portion. For automobiles, characterized in that the respective flanges fixed to the end portions of the respective coupling pipe portions are made to have substantially the same height by fixing the respective flanges to the respective coupling pipe portions of the metal pipe by welding. Exhaust manifold manufacturing method.