JP2828898B2 - Exhaust pipe joint structure and manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure of an exhaust pipe used for an engine of an automobile or the like and a method of manufacturing the same.

[0002]

2. Description of the Related Art An exhaust pipe joint structure for an automobile engine is disclosed in Japanese Utility Model Publication No. 5-13940 (hereinafter referred to as first prior art) and Japanese Utility Model Publication No. 5-19536 (hereinafter referred to as second prior art). What is known is known.

In the first prior art, as shown in FIG. 8, a flare portion 1A is formed at the end of an exhaust pipe 1 so as to extend outward. Further, a tapered cylindrical portion 2A that becomes thinner toward the tip is formed in the joint flange 2, and is fitted inside the flare portion 1A so as to overlap. An annular concave portion 3 is formed at the tip of the cylindrical portion 2A and the inner surface of the flare portion 1A, and is welded.

According to a second conventional technique, an end of a true cylindrical exhaust pipe 1 is fitted to a joint flange 2 and welded, and a reinforcing support 4 formed separately from the exhaust pipe 1 is attached to the exhaust pipe 1. One end 4A is welded to one surface 2A of the joint flange 2 and the other end 4B is welded to the exhaust pipe 1 over the outer periphery 1B.

[0005] Thus, both prior arts attempt to prevent breakage of the exhaust pipe welded to the joint flange.

[0006]

However, in the first prior art, it is necessary to form a tapered cylindrical portion 2A on the joint flange, so that the existing joint flange cannot be used or the exhaust pipe 1 cannot be used. The boundary 1C between the flare section 1A and the original pipe section has a problem that the wall thickness is reduced at the time of processing, and stress is concentrated on the boundary to easily break the section.

In the second prior art, since the adhesion between the exhaust pipe 1 and the reinforcing support 4 is low, stress concentrates on the welded portions of the reinforcing support ends 4A and 4B, and this end is easily damaged. In addition to the necessity of manufacturing the reinforcing support 4 separately from the exhaust pipe 1, there are many welding points, so that there are problems such as difficulty in manufacturing, high cost, and increase in weight.

Accordingly, an object of the present invention is to provide a joint structure between an exhaust pipe and a joint flange, which can solve such problems, and a method of manufacturing the same.

[0009]

In order to achieve the above object, a joint structure according to the present invention comprises a general diameter portion (A) followed by a gradual portion.
As the diameter changing portion (B) and the diameter increasing portion (C) reach the ends,
Reinforcement pipe of the same shape is fitted to the exhaust pipe formed sequentially
In what is made, reinforcement pipe and joint flange
(2) is the joint surface of the flange (2) (with the mating part)
On the opposite side, that is, on the inside, the exhaust pipe is
(1) is characterized by being integrally welded .

[0010]

According to the manufacturing method of the second invention, after the reinforcing pipe (5) is fitted to the end of the exhaust pipe (1), the side opposite to the tip (1A) of the exhaust pipe (1). The end (5B) of the reinforcing pipe (5) is kept at the original pipe diameter, and the exhaust pipe (1) is
The two pipes (1) and (5) are gradually expanded at the same time toward the tip (1A) to form a double contact tube, and the tip (1A)
(5A) is integrally welded and fixed to the joint flange (2) inside the joint flange (2).

The joint structure according to a third aspect of the present invention is a joint structure for an exhaust pipe in which the end of the exhaust pipe (1) is enlarged in diameter and welded and fixed to a joint flange (2). A long first reinforcing pipe (5) and a short second reinforcing pipe (9) are fitted in this order, and a general diameter section (A) is formed in a double pipe portion of the exhaust pipe (1) and the first reinforcing pipe. ), A first gradually changing diameter portion (B) is formed to be expanded, and further adjacent to the gradually changing diameter portion (B), the exhaust pipe (1) and the first and second reinforcing pipes (5) are formed. (9) A first enlarged diameter portion (C), a second gradually changed diameter portion (D), and a second
Of the second enlarged diameter portion (E) and the ends of the reinforcing pipes (5) and (9) are fixed to the joint flange (2). It is characterized by the following.

[0013]

[Function] Reinforcement pipe (5) overlapped and fitted to exhaust pipe (1)
However, over the general diameter portion (A), the gradually changing diameter portion (B), and the enlarged diameter portion (C) of the exhaust pipe, it comes into close contact with the end of the exhaust pipe, resulting in an increase in the section modulus due to a substantial increase in wall thickness. Increase the strength of the end. In addition, the thin portion where the diameter changes suddenly is reinforced by the increase in wall thickness, so that stress concentration is avoided.

In the fourth invention, the second reinforcing pipe further forms a triple pipe to further improve strength and disperse stress.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment shown in FIG. 1, a reinforcing pipe 5 is fitted to an exhaust pipe having a general diameter (original pipe diameter) in a range indicated by reference numeral A, and a reference numeral B adjacent to the general diameter portion A; Further, both pipes 1 and 5 are enlarged in diameter at a portion indicated by reference numeral C adjacent to the portion B.

At this time, the range B is formed in a tapered shape as a gradually changing diameter portion whose diameter is gradually increased, and the portion C is processed to a maximum diameter as an enlarged diameter portion. Such processing is performed by placing the two tubes 1 and 5 which are doubled in a female mold, and pushing an elastic body such as rubber into the inside of the exhaust pipe 1 to perform bulging. In addition, an expanding process in which the mold is opened from the inside with a split mold such as a punch may be used.

After forming the gradually changing diameter portion B and the expanded portion C in the form of a tightly attached double tube in this manner, the end portions 1A of both tubes 1, 5 are inserted into the insertion holes of the joint flange 2 for cold forging. And 5A are integrally inserted and welded and fixed to the joint flange 2. Reference numeral 6 indicates this welding.

The two tubes 1 and 5 can be spot-welded to each other to enhance the adhesion. In the first embodiment shown in FIG. 1, the diameter of the pipe is increased by one step, and both pipes 1 are bent at the bent portions 7 and 8.
Although a thin wall portion is formed between the first and second pipes, the stress is dispersed and the strength is increased by forming a close double pipe.

In the second embodiment shown in FIG.
Is formed in the same manner as in the first embodiment, but in the second embodiment, two gradually changing diameter portions B ₁ and B ₂ and two expanded portions are provided. The difference between the diameter portions C ₁ and C ₂ is that the diameter is increased in two stages.

The third embodiment shown in FIG. 3 corresponds to the third aspect of the invention, and a long first reinforcing pipe 5 and a short second reinforcing pipe 9 are fitted to the exhaust pipe 1 in order and overlapped. , And the tube is expanded in two stages as in the second embodiment. At this time, the second reinforcing pipe is expanded over the entire range.

In the third embodiment, the two-stage expansion is performed by the close contact triple tube. However, the three-stage expansion is performed by the close contact triple tube.
The number of reinforcing pipes can be increased, and the number of stages of pipe expansion can be increased. The fourth embodiment of FIG. 4 is different from the first embodiment of FIG. 1 in that the gradually changing diameter portion B is not tapered and has a spherical surface from the inside,
Although it is different in that it is constituted by the R surface from the outside, the reinforcing action is similar.

Fifth embodiment of FIG. 5 is that the second embodiment as compared to the second gradual change diameter B ₂ corresponding parts in FIG. 2 is constituted by a spherical different. The sixth embodiment shown in FIG. 6 is different from the first embodiment shown in FIG. 1 in that the tapered portion of the gradually changing diameter portion is formed in the axial direction of the exhaust pipe 1 so as to be wide and wide.

In the seventh embodiment shown in FIG. 7, an intimate double pipe in which an exhaust pipe 1 and a reinforcing pipe 5 are overlapped is expanded, and their ends are fixed to one side 2A of a joint flange 2 by welding. This is the same as the first embodiment shown in FIG.

[0024]

As described above, the joint structure of the exhaust pipe of the present invention is constructed as described above. Therefore, even when the thickness of the exhaust pipe is reduced by expanding the pipe, the pipe has a multi-pipe structure in which the reinforcing pipe is in close contact with the exhaust pipe. Because it is dispersed, there is no risk of cracks occurring at the flange welded part, bent part, gradually changing diameter part, and it is possible to reduce the thickness of the general part of the exhaust pipe, reducing weight and cost. I can do it. In addition, the existing flange can be used, and there is no need to separately manufacture a reinforcing pipe, and it can be processed simultaneously with the exhaust pipe. Moreover, since only a general diameter expanding process is required, manufacturing is easy, and the cost is reduced from this aspect. . In particular, in the present invention, the general diameter
Section, the gradually changing diameter section, and the reinforcing pipe extending across the enlarged diameter section
At the straight pipe near the flange and on the opposite side of the flange joint surface.
Since it is welded and fixed to the hand flange,
These parts are comprehensively reinforced while reinforcing
The joint strength can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a fourth embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a fifth embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a sixth embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a seventh embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of a conventional technique.

FIG. 9 is a longitudinal sectional view of another related art.

[Explanation of symbols]

First exhaust pipe 1A, 5A tip 2 coupling flange 5,9 stiffening tube 7,8 described bending portion A general diameter _{B, B 1, B 2,} D gradual change diameter _{C, C 1, C 2,} E expanded Department

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 7/08 F01N 7/18 F16L 23/024 F16L 23/026 F16L 23/028

Claims (3)

(57) [Claims] 1. A gradually changing diameter portion (B) following a general diameter portion (A).
And the enlarged diameter portion (C) is sequentially formed as it reaches the end.
Reinforcement pipe of the same shape is formed on the exhaust pipe to be fitted.
The reinforcing pipe and the joint flange (2)
Side opposite to the joint surface (with the mating part)
Inside the exhaust pipe (1) integrally with the enlarged diameter straight pipe part of the reinforcement pipe inside
An exhaust pipe joint structure characterized by being welded . 2. A reinforcing pipe (5) is fitted to an end of an exhaust pipe (1).
After joining, the side opposite to the tip (1A) of the exhaust pipe (1)
The end (5B) of the reinforcing pipe (5) is kept at the original pipe diameter.
Gradually toward the tip (1A) of the exhaust pipe (1).
Tubes (1) and (5) are expanded simultaneously to form a double tight tube,
The tip (1A) (5A) is attached to the joint flange (2),
An exhaust pipe characterized by being integrally welded and fixed inside of the exhaust pipe
Manufacturing method of the joint part. 3. An end of an exhaust pipe (1) is expanded in diameter to increase a joint flange.
In a joint structure of an exhaust pipe welded and fixed to a flange (2), a long first reinforcing pipe (5) and a short first reinforcing pipe are provided at an end of the exhaust pipe (1).
The two reinforcing pipes (9) are sequentially fitted, and the exhaust pipe (1) and the first
The first portion adjacent to the general diameter portion (A) at the double pipe portion with the reinforcing pipe
The gradually changing diameter portion (B) is expanded and formed.
Exhaust pipe (1) and first and second reinforcing pipes adjacent to (B)
(5) A first enlarged diameter portion (C) and a second
The gradually changing diameter portion (D) and the second enlarged diameter portion (E) are sequentially adjacent to each other.
Exhaust pipe of the second enlarged diameter portion (E) and both reinforcing pipes
(5) Fix the end of (9) to the joint flange (2).
And a joint structure for an exhaust pipe.