JP3509796B2 - exhaust manifold - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms the downstream ends of a plurality of exhaust single pipes extending from a plurality of exhaust ports of a multi-cylinder engine in a fan-shaped cross section, and combines the downstream ends of the plurality of exhaust single pipes in a circular shape. The present invention relates to an exhaust manifold integrated by welding.

[0002]

2. Description of the Related Art For example, an exhaust manifold used in a multi-cylinder engine for an automobile is a system in which a plurality of exhaust single pipes extending from a plurality of exhaust ports are integrally assembled. An exhaust gas purification device is connected. In order to smoothly connect a plurality of single exhaust pipes to an exhaust pipe or an exhaust gas purifying device having a circular cross section, for example, in an exhaust manifold for a four-cylinder engine, the downstream end of each single exhaust pipe has a central angle of 90 °. It is processed into a fan-shaped cross section, and the four exhaust single pipes are bundled into a circular cross section at their downstream ends and integrated by welding.

[0003]

By the way, the portions where the downstream ends of a plurality of exhaust single pipes are bundled into a circular cross section and integrated by welding are separated by the heat of the exhaust gas discharged during engine operation. There is a problem that thermal distortion occurs in the exhaust single pipe, and in particular, a portion corresponding to the essential point of the exhaust single pipe processed into a fan-shaped cross section becomes a heat spot, and cracks and buckling are likely to occur.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to prevent cracks and buckling from occurring in a weld portion where a plurality of exhaust single pipes of an exhaust manifold are integrated together.

[0005]

In order to achieve the above object, according to the invention described in claim 1, the downstream ends of a plurality of exhaust single pipes extending from a plurality of exhaust ports of a multi-cylinder engine are fan-shaped in cross section. In the exhaust manifold in which the downstream ends of the plurality of exhaust single pipes are combined in a circular shape and integrated by welding, the exhaust single pipes are formed on the inner surface of the portion corresponding to the corner of the fan-shaped cross section of each exhaust single pipe. Downstream end of
An exhaust manifold is proposed which is provided with a rigidity increasing portion extending along the longitudinal direction of the pipe from the edge toward the upstream side .

According to the above construction, in the exhaust manifold of the exhaust single pipe, the downstream ends formed in the fan-shaped cross section are combined in a circular shape and integrated by welding,
On the inner surface of a portion of each exhaust single pipe corresponding to the corner of the fan-shaped cross section, the length of the exhaust single pipe extends from the downstream edge of the exhaust single pipe to the upstream side.
By providing a rigidity increasing part that extends along the direction, it is possible to prevent cracks and buckling in the exhaust single pipe due to thermal expansion due to the heat of the exhaust gas, improving the durability and reliability of the exhaust manifold. Can contribute to.

Further, according to the invention described in claim 2,
In addition to the configuration of claim 1, there is proposed an exhaust manifold characterized in that an inner surface of a portion corresponding to a main part of a fan-shaped cross section of an exhaust single pipe is padded with a weld bead to form the rigidity increasing portion.

According to the above structure, since the exhaust manifold is originally assembled by welding a plurality of exhaust single pipes, the rigidity of the increased rigidity portion can be easily set only by adjusting the amount of buildup by the welding beads at the time of welding. It is possible to contribute to the improvement of durability and reliability of the exhaust manifold.

According to the invention described in claim 3,
In addition to the configuration of claim 1, there is proposed an exhaust manifold characterized in that a thick portion is formed in a portion corresponding to the essential part of a fan-shaped cross section of an exhaust single pipe to form the rigidity increasing portion.

According to the above construction, since the thick portion is formed in the portion corresponding to the essential part of the fan-shaped cross section of the exhaust single pipe to form the rigidity increasing portion, the rigidity increasing portion is formed at the time of manufacturing the exhaust single pipe. Processing time and processing cost can be reduced.

According to the invention described in claim 4,
In addition to the structure according to any one of claims 1 to 3, an exhaust manifold is proposed in which the wall thickness of the rigidity increasing portion gradually increases from the upstream side to the downstream side of the single exhaust pipe. To be done.

According to the above construction, the wall thickness of the rigidity increasing portion gradually increases from the upstream side to the downstream side of the exhaust single pipe, so that the wall thickness of the downstream end of the exhaust single pipe where cracks easily start is maximized. Not only can the reinforcing effect be further enhanced, but also stress concentration due to a sudden change in wall thickness can be avoided and durability can be further enhanced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings. 1 to 7 show a first embodiment of the present invention. FIG. 1 is a perspective view of an exhaust manifold, FIG. 2 is an exploded perspective view of the exhaust manifold, and FIG. 3 is a collecting portion of exhaust single pipes before welding. FIG. 4 is a perspective view of a single exhaust pipe, FIG. 5 is a perspective view of a collecting portion of the single exhaust pipe after welding, FIG. 6 is a sectional view taken along line 6-6 of FIG. 5, and FIG. FIG.

As shown in FIGS. 1 and 2, the exhaust manifold EM of an in-line four-cylinder engine has a plate-shaped mounting flange 11 which is connected to a cylinder head of the engine.
And four partition plates sandwiched between the four exhaust single pipes 12 to 15 whose upstream ends are welded to the mounting flange 11 and the downstream ends 12a to 15a of the four exhaust single pipes 12 to 15 gather. 16, 17 and the downstream end 1 of the four exhaust single pipes 12-15
An exhaust collecting pipe 18 connected to 2a to 15a and a mounting flange 19 for connecting the exhaust collecting pipe 18 to an exhaust pipe or an exhaust gas purifying device are provided.

The four exhaust single pipes 12 to 15 have different lengths and shapes from each other, but their downstream ends 12a.
.About.15a are formed in the same fan-shaped cross section having a central angle of 90.degree., And the downstream ends 12a to 15a thereof are combined so as to have a circular cross section with parts corresponding to the essential point p of the fan-shaped cross section facing each other. . At this time, the two partition plates 16 and 17 combined in a cross shape by the notches 16a and 17a formed in each are fixed so as to be sandwiched between the downstream ends 12a to 15a of the four exhaust single pipes 12 to 15. It

Two exhaust single pipes 12 and 13 extending from the # 1 cylinder and # 2 cylinder, and the # 3 cylinder and #
The first partition plate 16 for partitioning between the two single exhaust pipes 14 and 15 extending from the four cylinders is formed short, and the end edge 16b on the downstream side in the exhaust gas flow direction is the single exhaust pipes 12 to 15.
Are arranged flush with the edges of the downstream ends 12a to 15a. On the other hand, the second partition plate 17 for partitioning between the two exhaust single pipes 12 and 15 extending from the # 1 cylinder and the # 4 cylinder and the two exhaust single pipes 13 and 14 extending from the # 2 cylinder and the # 3 cylinder. The partition wall 17b on the downstream side in the exhaust gas flow direction projects from the end edges of the downstream ends 12a to 15a of the second partition plate 17 exhaust single pipes 12 to 15a. By the partition wall portion 17b of the second partition plate 17, it is possible to avoid the interference of the exhaust gas emitted from the cylinder whose explosion order is near.

A pair of edges 17c, 17c are formed on both side edges of the partition wall portion 17b of the second partition plate 17, and these edges 17c, 17c are four exhaust single pipes 12-15.
Are fitted into a pair of slits 18a, 18a formed in the exhaust collecting pipe 18 connected to the downstream ends 12a to 15a of the. The exhaust collecting pipe 18 is fitted with the upstream opening 18 that fits on the outer circumference of the downstream ends 12a to 15a of the four exhaust single pipes 12 to 15.
It is fixed by welding at b and the slit 1
Edges 17 of the second partition plate 17 at 8a and 18a
It is fixed to c and 17c by welding. At this time, in the exhaust collecting pipe 18 that is fitted and welded to the outer circumferences of the downstream ends 12a to 15a of the four exhaust single pipes 12 to 15, the upstream opening 18b of the exhaust collecting pipe 18 has the first partition plate 16 and the second partition plate. The protrusions 16c, 16c; 17d, 17d provided at both ends of the plate 17 are brought into contact with each other and positioned. The mounting bracket 19 fitted to the outer circumference of the exhaust gas collecting pipe 18 is fixed to the exhaust gas collecting pipe 18 by welding in a state where the upstream opening 19a thereof is positioned in contact with the protrusions 16c, 16c; 17d, 17d. It

Next, a procedure for assembling the exhaust manifold EM will be described.

First, as shown in FIG. 4, the downstream ends 12a to 15 formed in the fan-shaped cross section of each of the single exhaust pipes 12 to 15 are formed.
By overlaying the weld bead 20 on the inner surface of the portion corresponding to the point p of a, the downstream ends of the respective exhaust single pipes 12 to 15
Forming an increased rigidity portion extending along the longitudinal direction of the pipe from the edge of the pipe to the upstream side . Subsequently, after the upstream ends of the four exhaust single pipes 12 to 15 are welded to the mounting bracket 11, as shown in FIG. 3, the first ends are combined in a cross shape in the gaps of the downstream ends 12a to 15a gathered in a circular shape. The partition plate 16 and the second partition plate 17 are fitted together. Subsequently, as shown in FIGS. 5 and 6, the downstream ends 12a to 15a of the four exhaust single pipes 12 to 15 and the first and second partition plates 16 and 17 which are bundled in a circle.
Weld 21 together.

As described above, the downstream ends 12a to 15a of the four exhaust single pipes 12 to 15 which are bundled in a circle and the portions 21 where the first and second partition plates 16 and 17 are welded, particularly the exhaust single pipe 12 is used.
Even if the thermal stress due to the heat of the exhaust gas of the engine acts on the portion corresponding to the point p of the downstream ends 12a to 15a of -15, the reinforcing action of the weld bead 20 as the rigidity increasing portion causes 4
It is possible to prevent cracks and buckling from occurring at the downstream ends 12a to 15a of the exhaust single pipes 12 to 15 of the book, and contribute to improvement in durability and reliability of the exhaust manifold EM (FIG. 7 (A)). reference). Moreover, the welding bead 20
The height of rigidity can be set arbitrarily by adjusting the amount of padding due to, so that reliability and durability are further improved.

On the other hand, as shown in FIG.
In the conventional one in which the downstream ends 12a to 15a of the exhaust single pipes 12 to 15 are not reinforced by the weld beads 20, thermal expansion of the exhaust single pipes 12 to 15 due to the heat of the exhaust gas causes the downstream ends 12a to 15a of the exhaust single pipes 12 to 15a to expand. There are problems that a crack c is generated in the vicinity of the welded portion 21 and a buckling b is generated.

Finally, the exhaust collecting pipe 18 is provided at the downstream ends 12a to 15a of the four exhaust single pipes 12 to 15 which are bundled in a circle.
And the mounting flange 19 is welded to complete the exhaust manifold EM. Next, another embodiment of the present invention will be described with reference to FIG.

In the above-described first embodiment, the exhaust single pipe 12 ...
Although a weld bead 20 is provided in a portion of the downstream ends 12a to 15a of 15 corresponding to the point p, the rigidity is increased.
In the second embodiment shown in (A), the rigidity is increased by providing the thick portion 22 having an increased thickness in the portion corresponding to the required p. According to the second embodiment, the thick portion 22 can be formed at the same time when the exhaust single pipes 12 to 15 are manufactured.
The number of processing steps can be further reduced to contribute to cost reduction.

The third embodiment and the fourth embodiment shown in FIGS. 8B and 8C are modifications of the first embodiment and the second embodiment, respectively, and are the welding of the first embodiment. While the bead 20 and the thick portion 22 of the second embodiment have a constant thickness in the longitudinal direction, the weld bead 2 of the third embodiment is used.
0 and the thick portion 22 of the fourth embodiment are the single exhaust pipes 12 to 15
The wall thickness gradually increases from the upstream side to the downstream side. With this, the exhaust single pipe 12 to 15 which is the most difficult in terms of strength
The rigidity of the end faces of the downstream ends 12a to 15a of the exhaust gas is effectively increased, and the rigidity is prevented from abruptly changing between the weld bead 20 and the portion where the thick portion 22 is not provided, and the exhaust manifold EM The durability and reliability of can be further improved.

Although the embodiments of the present invention have been described in detail above, the present invention can be modified in various ways without departing from the scope of the invention.

For example, in the first embodiment, each exhaust single pipe 1
After forming the weld bead 20 on the downstream ends 12a to 15a of the exhaust pipes 2 to 15, the downstream ends 12a to 15 of the exhaust single pipes 12 to 15 are formed.
a and the first and second partition plates 16 and 17 are welded 21, but the downstream ends 12a to 15a of the exhaust single pipes 12 to 15 and the first and second partition plates 16 and 17 are welded to each other, and then downstream. The weld beads 20 may be formed on the ends 12a to 15a.

Further, the exhaust manifold E of the embodiment
M is provided with a first partition plate 16 having no exhaust gas separation effect and a second partition plate 17 having an exhaust gas separation effect at the collecting portion of the exhaust single pipes 12 to 15. The second partition plates 16 and 17 may not both have the effect of separating exhaust gas, and the first and second partition plates 16 and 17 may be used.
May be abolished.

[0028]

As described above, according to the invention described in claim 1, in the exhaust manifold, a plurality of exhaust single pipes are combined in a circular shape by combining downstream ends formed in a fan-shaped cross section, and integrated by welding. On the inner surface of the part corresponding to the corner of the fan-shaped cross section of each exhaust single pipe,
By providing the increased rigidity portion extending from the edge of the flow end to the upstream side along the longitudinal direction of the pipe, thermal expansion due to the heat of the exhaust gas corresponds to the corner of the fan-shaped cross section of the single exhaust pipe. Heats part
Even if it becomes a pot, it is possible to prevent the single exhaust pipe from cracking or buckling, which contributes to the improvement of the durability and reliability of the exhaust manifold.

According to the invention described in claim 2,
Originally, the exhaust manifold is assembled by welding multiple exhaust single pipes, so at the time of welding, it is possible to easily set the rigidity of the increased rigidity part by adjusting the amount of buildup by the welding beads, which makes the exhaust manifold durable. It can contribute to the improvement of the reliability and the reliability.

According to the invention described in claim 3,
Since a thickened portion was formed in the portion corresponding to the corner of the fan-shaped cross section of the exhaust single pipe to form the rigidity increasing portion, it is possible to reduce the processing time and processing cost by forming the rigidity increasing portion at the time of manufacturing the exhaust single pipe. You can

According to the invention described in claim 4,
Since the wall thickness of the rigidity increasing part gradually increases from the upstream side to the downstream side of the exhaust single pipe, it is not only possible to maximize the wall thickness of the downstream end of the exhaust single pipe where cracks are likely to start and further enhance the reinforcing effect. In addition, stress concentration due to a sudden change in wall thickness can be avoided and durability can be further improved.

[Brief description of drawings]

FIG. 1 is a perspective view of an exhaust manifold.

FIG. 2 is an exploded perspective view of an exhaust manifold

FIG. 3 is a perspective view of a collecting portion of the exhaust single pipe before welding.

FIG. 4 is a perspective view of an exhaust single pipe.

FIG. 5 is a perspective view of a collecting portion of the exhaust single pipe after welding.

6 is a sectional view taken along line 6-6 of FIG.

FIG. 7 is an enlarged view of part 7 of FIG.

FIG. 8 is a perspective view of a single exhaust pipe according to second to fourth embodiments of the present invention.

[Explanation of symbols]

12 to 15 single exhaust pipe 12a to 15a Downstream end 20 weld beads 21 welding 22 Thick part p required

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Koichi Fujimori 1-4-1 Chuo, Wako-shi, Saitama, Ltd. Honda R & D Co., Ltd. (72) Inventor Makoto Nakata 1-4-1 Chuo, Wako-shi, Saitama Stock (56) References JP-A-8-61058 (JP, A) JP-A-7-178585 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01N 7 / 18 B23K 9/04 F01N 7/10 F16L 9/19 B23K 101: 06

Claims (4)

(57) [Claims] 1. A downstream end (12a) of a plurality of exhaust single pipes (12-15) extending from a plurality of exhaust ports of a multi-cylinder engine.
15a) are formed in a fan-shaped cross section, and the downstream ends (12a-15a) of the plurality of exhaust single pipes (12-15) are combined in a circular shape and integrated by welding (21). On the inner surface of the portion corresponding to the point (p) of the fan-shaped cross section of the pipe (12 to 15) , the exhaust single pipe (12 to 15) is
The length of the pipe from the edge of the downstream end (12a to 15a) to the upstream side
An exhaust manifold comprising a rigidity increasing portion extending along the direction . 2. The rigidity increasing portion is characterized in that an inner surface of a portion corresponding to the point (p) of the fan-shaped cross section of the exhaust single pipe (12 to 15) is built up with a weld bead (20) to form the rigidity increasing portion. The exhaust manifold according to claim 1. 3. The rigidity increasing portion is formed by forming a thick portion (22) at a portion corresponding to a point (p) of a fan-shaped cross section of the exhaust single pipe (12 to 15). The exhaust manifold according to 1. 4. The exhaust single pipe (12) has a wall thickness of the rigidity increasing portion.
To 15), the exhaust manifold gradually increases from the upstream side to the downstream side.