JPS63170515A - Exhaust manifold for engine - Google Patents

Abstract

PURPOSE:To make the whole structure lightweight and form a complex manifold case by using branch pipes of an exhaust manifold made of a pipe and using the manifold case made of a casting. CONSTITUTION:The upstream ends of branch pipes 1 made of a metal pipe are welded to a fitting flange 2, and the downstream ends are welded to a cluster case 8 made of a casting. Accordingly, the whole manifold can be made lightweight, and the cluster case can be formed into a complex shape.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust manifold for an engine having a plurality of exhaust ports.

(Prior Art) Conventionally, this type of exhaust manifold has either been made by casting the branch pipe and the collection case as one unit, or by casting the branch pipe and collection case as one body, or by casting the branch pipe and collecting case as one body, or by casting the exhaust manifold as a single unit, as in the case described in Japanese Patent Application No. Shoei-IS9681 previously filed by the applicant of the present application. Generally, the branch pipe is formed from a metal pipe, the collection case is formed from a press molded product, and these are assembled by welding.

(Problems to be Solved by the Invention) The above-mentioned conventional one-piece cast product has the drawback of increasing the weight because the shape is large, so it is necessary to increase the wall thickness of the product in consideration of the surrounding area. there were. In addition, in the case of the above-mentioned prior application, the shape of the case is limited by press molding, and if the internal structure of the case needs to be formed in a complicated manner, the case must be divided into halves. However, it is necessary to weld the halves of the case together and also to weld accessories such as internal ribs, which not only increases the number of welding points but also increases the number of parts and work processes.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust manifold in which the branch pipes are pipes and the collecting case is made of cast metal, thereby making it possible to reduce the overall weight and make the collecting case more complex.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a plurality of branch pipes connected to a plurality of exhaust ports of an engine, and a structure in which each branch pipe is connected to a cylinder at the upstream end of each branch pipe. In an exhaust manifold consisting of a mounting flange attached to the block and a collection case connected to the downstream end of each branch pipe, each branch pipe is formed of a metal pipe, and each collection case is formed of a cast product. , these are welded together.

(Function) Compared to the case where the branch pipe is cast integrally with the collecting case to make pipes, the branch pipe can be made thinner and lighter in weight, and since the collecting case is a cast product, the structure can be made more complex. ,
Since only the collective case is cast, it is easy to use on site and can be cast thinly, making it possible to significantly reduce the size of the entire exhaust manifold.

(Example) A case where the present invention is applied to a four-cylinder engine will be described.

Referring to FIGS. 1 to 3, (1) indicates a branch pipe connected to each exhaust port of the engine, and the branch pipe (1)
(1) (1) (1) has a mounting flange (
2) is fixed to the cylinder block of the engine via the flange (2), and the downstream end is fixed to the collecting case (3).
), the exhaust gas flowing in from each exhaust port passes through each of the branch pipes (1) and joins within the collecting case (3), and an exhaust catalyst is connected to the downstream side of the collecting case (3). I tried to lead to.

The branch pipe (1) is formed of a metal pipe, and is welded to the mounting flange (2) and the collection case (3) at the upstream and downstream ends, respectively, and is formed into a curved shape between them, so that the branch pipe (1) This minimizes the frictional resistance of the exhaust gas flowing inside.

The collecting case (3) is made of cast metal, and has inlet openings (3a) (3a) at its upstream end on the same axis of each branch pipe (1).
(3a) (3a) Protrudingly provided, each of the flow openings (3a)
The branch pipes (1) are inserted into and welded, and in detail, as shown in FIG. 1-cloud 3
- In the case of cloud 4-12, as shown in Figure 4, the branch pipes (1) (1) connected to I2 and No. 3 in the center are connected to a pair of inlet openings (3a) (3a) on the separate side of the engine. The branch pipes (1) connected to 11 and 4 on both sides were connected to a pair of inflow openings (3a) (3a) on the engine side.

Inside the collective case (3), each inflow opening (3a) is provided.
Two consecutive curved passages (3b) (3bH3bH3b) are formed, and among the multiple passages (3b), a passage (3b) (3b) connected to I2 and number 3 and a passage (3b) connected to il and I4 are formed.
H3b) are merged on the downstream side so that their axes form an acute angle to form a merging chamber (3cH3c) at the merging point, and the downstream end of each merging 13c) is further narrowed down its peripheral wall to form the collecting case. (3), and form circular outflow openings (3d) (3d) as shown in Fig. 5, and the diameter of each outflow opening (3d) is approximately the diameter of the branch pipe (1). The exhaust gas is guided into a catalyst case fixed to a flange (3C) provided on the outer periphery of the downstream end of the collecting case (3).

The mounting flange (2) is formed into a rectangular plate shape with D for all the exhaust ports, and long holes (2aH2aH2aH2a) are provided at positions facing each exhaust port.
Insert each branch pipe (1) into 2a) and weld it,
In addition, a plurality of bolt holes (2b) surround the long hole (2a).
) to fix each branch pipe (1) to the cylinder block.

The branch pipe (1) and the collecting case (3) are made of a heat-resistant, high-strength material, such as austenitic stainless steel.

In the figure, (4) indicates the mounting hole of the 02 sensor, and the mounting hole (
4) is a detection port (4a) provided in the partition between the confluence chamber (3C) connected to No. 11 and No. 4 and the passageway (3b) connected to I3,
A passage (3b) is provided so that the sensor faces so that the exhaust gases No. 11, No. 4, and I3 come into contact with the sensor, and a passage (3b) connected to No. 3 and I2 located upstream from the mounting hole (4). Through the through hole (4b) provided in the partition wall of 3b),
The exhaust gas was introduced into the passage No. 3 (3b) and brought into contact with the sensor, so that a value of 0□ was detected.

(5) in the figure shows the mounting hole for the hot air cover.

As described above, according to the above embodiment, the branch pipe (1) is made of a metal pipe made of corrosion-resistant and high-strength material, which prevents corrosion and makes it possible to reduce the thickness and weight, and the collecting case (3) is cast by casting. By making the cluster case (3) a large piece, it is possible to use many curved surfaces in its internal structure, etc., and form a complex flow path that takes into consideration the good flow of exhaust gas. The distance from the end to the end is short,
It has good tidal rotation and can be formed into a thin wall.

Furthermore, by merging the exhaust gases that do not occur before or after the exhaust process, that is, the exhaust gases I2 and I3 and I1 and I4, it is possible to prevent mutual interference of the exhaust gases in the merging chamber (3C), and also to prevent the exhaust gases from interfering with each other in the merging chamber (3C). By making the diameter of (3d) approximately the same as the diameter of the branch pipe (1), the cross-sectional area of the exhaust gas flow path can be kept constant, and cooling due to adiabatic expansion of the exhaust gas can be prevented. The efficiency of the exhaust catalyst downstream of the outflow opening (3d) is not reduced.

(Effects of the Invention) As described above, according to the present invention, it is lighter than when it is integrally formed by casting, and the structure of the collection case can be made more complicated than when pipes and pipe products are assembled by welding. , and also has the effect of making it possible to reduce weight, which is the advantage of the latter.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a left side view, FIG. 3 is a right side view, FIG. 4 is a front view of the collection case, and FIG. 5 is a bottom view of the collection case. Figure 6 shows Vl-V in Figure 1.
7 is a cross-sectional view taken along the line ■--■ in FIG. 6. (1)...Branch pipe (ii...Mounting flange<3)...Combining case (3C)...Combining chamber (3
d)...2 people outside the outflow frontage Figure 6

Claims (1)

[Claims] 1. A plurality of branch pipes connected to a plurality of exhaust ports of the engine, a mounting flange provided at the upstream end of each branch pipe to attach each branch pipe to the cylinder block, and a mounting flange provided downstream of each branch pipe An exhaust manifold consisting of a collecting case connected to an end of the exhaust manifold, wherein each of the branch pipes is formed of a metal pipe, each of the collecting cases is formed of a cast product, and these are welded together. manifold. 2. The engine exhaust according to claim 1, wherein the collecting case is formed to have a plurality of collecting chambers connecting branch pipes in which exhaust processes do not occur one after the other. manifold.