JPH08210131A - Exhaust manifold of internal combustion engine - Google Patents

Abstract

PURPOSE: To provide an exhaust manifold for internal combustion engine, in which resistance against crack generation at the tine part in a branch pipe is enhanced. CONSTITUTION: The first split half 41 and the second split half 42 are confronted to each other while a receptacle piece 41 of the first 41 is put mating with the end of the second 42, and a reinforcing plate 9 is applied from the outside, followed by a MIG welding process, and thus a welded part 73 is formed so that a single piece structure is accomplished. The whole circumference of the reinforcing plate 9 is welded. The first half 41, second half 42, and plate 9 are made of ferrite series stainless steel and have the same thickness. The tine part 7 likely to generate cracks is covered with the plate 9 as reinforcement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold for an internal combustion engine having improved crack resistance.

[0002]

2. Description of the Prior Art Internal combustion engines are equipped with an exhaust manifold. The exhaust manifold is for guiding the high temperature exhaust gas discharged from the combustion chamber of the internal combustion engine to the exhaust pipe. As an exhaust manifold, there is a welding system shown in FIGS. 5 and 6 (JP-A-4-265418). Figure 6
Shows an arrow view taken along line W6-W6 of FIG.

According to this, the first half body 201 and the second half body 202 formed by press working are used so that the first half body 201 and the second half body 202 face each other. Together, they will be welded together. In this structure, as shown in FIG. 5, a plurality of branch pipes 101 connected to an exhaust port of a combustion chamber of an internal combustion engine and a branch pipe 10 are provided.
A merging pipe 102 in which 1 merges, and an exhaust passage 103 penetrating the diverging pipe 101 and the merging pipe 102 are provided.

Further, as the exhaust manifold, there is a cast product type integrally formed of cast iron. In this case,
It is known that the branch pipes 101 are integrally connected by a film-like film rib 105 extending from a crotch portion 107 connecting the branch pipes 101 to an upstream end 101f of the branch pipe 101 as shown in FIG. (Japanese Utility Model Publication No. 5-926).

By the way, in the exhaust manifold, when the internal combustion engine is driven, high-temperature exhaust gas passes through the exhaust passage 103, so that the exhaust manifold is heated and thermally expanded.
When the internal combustion engine is stopped, the exhaust manifold is cooled from the heated state, so that the exhaust manifold thermally contracts. Here, the crotch portion 107 connecting the branch pipes 101 is a portion where thermal stress due to thermal expansion and thermal contraction is most concentrated, and therefore cracks are often generated.

[0006]

However, according to the exhaust manifold of the above-mentioned form, the effect of suppressing cracks in the crotch portion 107 is not always sufficient. Even in the exhaust manifold according to FIG. 7, it is expected that the reinforcing effect at the crotch portion 107 can be enhanced by the film rib 105, but the crack suppressing effect is not sufficient.

The present invention has been made in view of the above situation, and an object of the present invention is to provide an exhaust manifold for an internal combustion engine having improved crack resistance in the crotch portion connecting the branch pipes.

[0008]

According to a first aspect of the present invention, there is provided an exhaust manifold for an internal combustion engine, wherein a plurality of branch pipes, a confluence pipe where the respective branch pipes meet, a branch pipe and a confluence pipe, and exhaust gas An exhaust manifold for an internal combustion engine having a flowing exhaust passage, characterized in that a reinforcing plate is applied to and welded to at least one crotch portion connecting the branch pipes. .

The exhaust manifold uses a first half body and a second half body, which are approximately half-divided in the thickness direction. The first half body and the second half body are used.
It is possible to adopt a structure in which the manifold main body is formed by welding the halves together.

[0010]

In the exhaust manifold, when the internal combustion engine is driven, the high temperature exhaust gas flows in the exhaust passage, so that the exhaust gas is heated and thermally expands. When the internal combustion engine is stopped, the inflow of the exhaust gas is stopped. Therefore, it may be cooled from the heated state and heat contraction may occur. According to the exhaust manifold of the present invention, the reinforcing plate is applied to the crotch portion connecting the branch pipes and joined by welding. Therefore, the crotch portion where stress concentration tends to occur can be reinforced, and the crack resistance in the crotch portion can be enhanced as compared with the conventional form. Therefore, it can contribute to the durability and longer life of the exhaust manifold.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. This exhaust manifold is installed on the exhaust side of the internal combustion engine. As can be understood from FIG. 1, the exhaust manifold includes a manifold main body including a plurality of branch pipes 1, a confluence pipe 2 in which the respective branch pipes 1 join, and an exhaust passage 3 penetrating the branch pipes 1 and the confluence pipe 2. 4 is the main subject.
The exhaust gas discharged from the internal combustion engine flows through the exhaust passage 3 from upstream to downstream in the direction of arrow A1.

Further, a first mounting flange portion 51 to be mounted on the internal combustion engine is welded to the manifold body 4 so as to be located on the upstream side of the branch pipe 1. A second attachment flange portion 52 attached to the exhaust pipe is welded to the manifold body 4 so as to be located on the downstream side of the merging pipe 2. First mounting flange portion 51 and second mounting flange portion 5
2 is formed of a steel material having excellent weldability such as a welded structural steel material (JIS SPHC). In addition, the branch pipe 1 installed next to
A boundary space portion 6 is defined between the spaces.

In this embodiment, as shown in FIG. 1, the branch pipe 1 is connected by the crotch portions 7 and 8. An arrow view taken along the line W2-W2 in FIG. 1 is shown in FIG. In this embodiment, FIG.
As can be understood from FIG. 1, a first half body 41 and a second half body 42 in which the manifold body 4 has a substantially half structure in the radial direction.
To use. Further, a small piece tongue-shaped reinforcing plate 9 is used. The first half body 41 and the second half body 42 are formed by bending a plate body into a three-dimensional curved surface shape by press working. The reinforcing plate 9 is also formed by bending the plate body into a three-dimensional curved surface by press working.

According to the present embodiment, since the exhaust passage 3 also has a half-split structure, the trough-shaped space defined by the inner wall surface 41x of the first half-split body 41 and the inner wall surface 42x of the second half-split body 42. The exhaust passage 3 is formed by the gutter-shaped space partitioned by.
As shown in FIG. 4, in the region near the crotch portions 7 and 8 of the first half-split body 41, a substantially collar-shaped receiving piece 41m is integrally extended from the opening end side of the first half-split body 41. ing. As can be understood from FIG. 2, the first half-split body 41 and the second half-split body 42 are positioned while aligning the opening end of the second half-split body 42 with the receiving piece 41m of the first half-split body 41. Facing each other,
A small piece tongue-shaped reinforcing plate 9 is applied from the outside so as to cover the receiving piece 41m, and further, MIG welding is performed in a shield atmosphere such as inert gas to form a welded portion 73.
The first and second halves 42 and the reinforcing plate 9 are integrally connected.

As described above, the receiving piece 41 of the first half-split body 41
m can be expected to have a position regulation function of regulating the position when the first half body 41 and the second half body 42 are coupled. As can be seen from FIG. 4, the welded portion 73 where the reinforcing plate 9 is welded is shown by the hatched region, and therefore, the entire circumference of the reinforcing plate 9 is welded. In this state, the reinforcing plate 9 has the receiving piece 41.
covers m.

According to this embodiment, as can be understood from FIG. 2, the reinforcing plate 9 has a bent portion 9r having a shape corresponding to the bent portion of the receiving piece 41m. A position regulating function for regulating the position of the reinforcing plate 9 can be expected by the bent portion 9r of the reinforcing plate 9 and the receiving piece 41m. In FIG. 2, welded portions 73a, 73b, 73c forming the welded portion 73 are shown. The welded portion 73a is the end surface 41 of the receiving piece 41m of the first half-split body 41.
h, the end surface 9h of the reinforcing plate 9, the outer surface portion 4 of the second half-split body 42
It covers and binds 2p. The welded portion 73b is the reinforcing plate 9
End surface 9i and the outer surface portion 41p of the first half-divided body 41 are joined together. The welded portion 73c covers the end surface 41i of the first half-split body 41 and the outer surface portion 42n of the second half-split body 42 to join them.

In this embodiment, the first half body 41 and the second half body 42 are made of ferritic stainless steel (JIS SUS).
430), but may be austenitic stainless steel or other kinds of alloy steel. The reinforcing plate 9 is formed of the same or the same material as the first half body 41 and the second half body 42. Welding integrity and thermal expansion coefficient are taken into consideration.

Conventionally, the portion of the crotch portion 7 where a crack is likely to occur due to stress concentration is a portion indicated by an arrow K in FIG. 2 or a portion in the vicinity thereof. According to the present embodiment, the reinforcing plate 9 is covered and joined from the outside to the portion of the crotch portion 7 where a crack is likely to be generated due to stress concentration, and is reinforced by covering the portion. In this embodiment, the first half body 41 and the second half body
Although the average thickness t of the half-split body 42 can be appropriately selected, it can be generally about 1 to 2 mm, for example, 1.5 mm. The thickness of the reinforcing plate 9 can be appropriately selected, but basically, the first half body 4
It has the same value as the thickness of the first and second halves 42.

According to this embodiment, as can be understood from FIG. 1, the reinforcing plate 9 is welded to the crotch portion 7,
The reinforcing plate 9 is not welded to the other crotch portion 8 on the other side. This is because the other crotch portion 8 is less likely to crack. The main reason for this is that although the length L1 of the branch pipe 1 connected via the crotch portion 7 is short, the length L2 of the branch pipe 1 connected via the crotch portion 8 is long, so that stress concentration occurs in the crotch portion 8. It is estimated that there are few.

As described above, according to the present embodiment, the portion of the crotch portion 7 where cracks are easily generated in the past is reinforced by covering and joining the reinforcing plate 9 from the outside. Therefore, even if stress concentration occurs, it can be received by the reinforcing plate 9, so that the crack resistance of the crotch portion 7 is improved. In addition, the effect that the stress concentration can be dispersed in the entire reinforcing plate 9 can be expected. It is conceivable to adopt a method of changing the shape of the crotch portion in the exhaust manifold in order to improve the crack resistance, but in this case, fluctuations in the flow passage resistance of the exhaust passage 3 are easily induced. In this case, it becomes necessary to re-evaluate the function of the exhaust manifold. In this respect, according to the present embodiment, since the method of covering and joining the reinforcing plate 9 from the outside is adopted, there is no change in the flow resistance of the exhaust passage 3 and the above inconvenience can be eliminated.

(Other Example) In the above-mentioned example, the reinforcing plate 9 is welded to only the crotch portion 7 of the crotch portions 7 and 8, but depending on the type of exhaust manifold, both the crotch portions 7 and 8 are joined. The reinforcing plate 9 may be joined by welding. In the above-described example, the average thickness of the reinforcing plate 9 is basically the same as the first half body 41 and the second half body 42, but the thickness is not limited to this, and may depend on the type of exhaust manifold. Can be thicker or thinner than the first half body 41 and the second half body 42.

In the above-mentioned example, the manifold body 4 relating to the exhaust manifold is a welded product formed by welding the first half body 41 and the second half body 42, but it is not limited to this. Alternatively, the exhaust manifold may be formed by a cast product integrally cast from spheroidal graphite cast iron, alloy cast iron, cast steel, etc., and the reinforcing plate 9 may be applied to at least one of the crotch portions of the cast product by applying welding. good.

Although MIG welding is used in the above-mentioned example, the welding means is not limited to this, and known means such as TIG welding, resistance welding, spot welding, and projection welding may be used. (Supplementary Note) The following technical idea can be understood from the above-described embodiment. The at least one crotch portion connecting the branch pipes has a three-dimensional curved surface shape, the reinforcing plate has a tongue shape, and has a three-dimensional curved surface shape corresponding to the three-dimensional curved surface shape of the crotch portion. An exhaust manifold for an internal combustion engine as set forth in. The reinforcing plate is not joined to the crotch portion connecting the long branch pipes, and the reinforcing plate is joined to the crotch portion connecting the short branch pipes. Exhaust manifold.

[Brief description of drawings]

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

FIG. 2 is a view taken along line W2-W2 of FIG.

FIG. 3 is an enlarged perspective view showing a state in which a reinforcing plate is applied to a crotch portion.

FIG. 4 is an enlarged perspective view showing a portion where a reinforcing plate is applied to a crotch portion and welded.

FIG. 5 is a configuration diagram of an exhaust manifold according to a conventional technique.

6 is a view taken along the line W6-W6 of FIG. 5 according to the related art.

FIG. 7 is a configuration diagram of an exhaust manifold according to a conventional technique.

[Explanation of symbols]

In the figure, 1 is a branch pipe, 2 is a confluent pipe, 3 is an exhaust passage, 4 is a manifold main body, 41 is a first half-split body, 42 is a second half-split body,
Reference numerals 7 and 8 denote crotch portions, 73 denotes a welded portion, and 9 denotes a reinforcing plate.

Claims (1)

[Claims] 1. An exhaust manifold for an internal combustion engine, comprising: a plurality of branch pipes, a confluent pipe where the respective branch pipes join, and an exhaust passage that passes through the branch pipes and the confluent pipe and through which exhaust gas flows. An exhaust manifold for an internal combustion engine, wherein a reinforcing plate is applied to at least one crotch portion connecting the branch pipes and joined by welding.