JPH04234518A - Exhaust manifold - Google Patents

Abstract

PURPOSE:To adjust the shape of a portion where branches and a main tube of an exhaust manifold are connected each other. CONSTITUTION:A spherical roof 9 is provided on a connection part of the main tube 8 with branches 6a, 6b, 6c, and the 6d, and the branches 6a, 6b, 6c, and 6d are welded to the roof 9 to be communicated with the main tube 8. This eases deburring, and improves rigidity without being influenced by vibration.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold attached to a multi-cylinder engine mounted on an automobile.

0002

2. Description of the Related Art Hitherto, four-stroke multi-cylinder engines have generally been used as automobile engines. When a four-cylinder engine is installed, as shown in FIGS. 4 and 5, there are four branches 1a, 1b, 1c, and 1d aligned with the exhaust port of each cylinder, and one end of the An exhaust manifold 4 is attached which is fixed to the bracket 2 in parallel and whose other end is connected to the main pipe 3. In this structure, the exhaust gas flow in the exhaust manifold 4 (the center of each branch is indicated by a dashed line in the figure) is
The exhaust gases in a, 1b, and 1c merge first and form branch 1.
The exhaust gases d are then combined and discharged.

[0003] When the cylinders are assembled separately in this way, the adjacent branches 1a and 1b
, exhaust interference will occur because the distance between branch 1c and branch 1d is short. That is, branch 1a
The exhaust gas discharged from the branch 1d flows back into the cylinder through the branch 1b at the end of the exhaust process, and the exhaust gas discharged from the branch 1d flows back into the cylinder through the branch 1c at the end of the exhaust process, impeding scavenging. This will lead to deterioration of combustion, resulting in a decrease in output and a negative impact on fuel efficiency.

On the other hand, as shown in FIGS. 6 and 7, each branch 1a, 1b, 1c, and 1d is lengthened and connected directly to the outer periphery of the cylindrical main pipe 3 (see FIG. 8). When the manifold 4a is installed, the exhaust gas flows inside the manifold 4a are all merged at one point P connected to the main pipe 3, thus solving the above problem. Note that Japanese Patent Application Laid-Open No. 57-86515 discloses a structure for connecting a plurality of exhaust pipes together to a collective exhaust pipe (main pipe). Furthermore, Japanese Utility Model Publication No. 58-36810 discloses forming a guide surface for arbitrarily bending the flow of exhaust gas in the main pipe.

[0005]

However, as shown in FIG. 8, this exhaust manifold 4a has four branches connected to the outer periphery of the cylindrical main pipe 3, so the space is narrow and burrs are formed on the surface of the connecting part. cannot be taken easily. For this reason, there is a possibility that noise may be generated due to the influence of vibration or the like, or that the rigidity may be adversely affected.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust manifold whose shape is adjusted so that the joint between the branch and the main pipe is not affected by vibrations.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an exhaust manifold in which a plurality of branches arranged at the exhaust side ports of each cylinder of an engine are concentrated in a main pipe and connected to an exhaust pipe. It is characterized in that a substantially spherical roof is formed at the opening of the main pipe, and a plurality of branches are connected via the spherical roof.

[0008]

[Function] By adopting the above-mentioned structure of the present invention, the space at the connecting portion between the main pipe and the branch is expanded, and burrs can be easily removed during welding.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, an exhaust manifold 5 attached to an in-line four-cylinder engine has four branches 6.
a, 6b, 6c, and 6d, and each branch is of equal length, one end of which is fixed in parallel to a bracket 7, and the other end welded to a main pipe 8 connected to an exhaust pipe (not shown). . Here, as shown in FIG. 3, a substantially spherical roof 9 is formed at the opening of the main pipe 8, and each branch 6a,
Weld 6b, 6c, and 6d to connect them.

[0010] As a result, each branch 6a, 6b,
A gap is created between 6c and 6d, making it easy to deburr from the F direction. Further, the inside of the connecting portion is expanded, and the exhaust gas flows diagonally from above, thereby reducing interference with the cylinder due to backflow of exhaust gas.

[0011]

According to the present invention, as constructed as described above, the joint space is expanded, the welded portion of the branch can be easily deburred, and the rigidity can be improved without being affected by vibration. Additionally, exhaust pulsation can be alleviated internally, eliminating output loss and improving fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a front view of an exhaust manifold according to an embodiment of the present invention.

FIG. 2 is a side view of the exhaust manifold shown in FIG. 1.

FIG. 3 is an explanatory diagram of main parts of the exhaust manifold shown in FIG. 1;

FIG. 4 is a front view of a conventional exhaust manifold.

FIG. 5 is a side view of the exhaust manifold shown in FIG. 4.

FIG. 6 is a front view of another conventional exhaust manifold.

7 is a side view of the exhaust manifold shown in FIG. 6. FIG.

8 is an explanatory diagram of main parts of the exhaust manifold shown in FIG. 6. FIG.

[Explanation of symbols]

5 Exhaust manifold 6a Brunch 6b Brunch 6c Brunch 6d brunch 8. Supervisor 9 Spherical roof

Claims (1)

[Claims] Claim 1: An exhaust manifold in which a plurality of branches disposed at the exhaust side ports of each cylinder of an engine are gathered in a main pipe and connected to the exhaust pipe, in which a substantially spherical roof is formed at the opening of the main pipe; An exhaust manifold characterized by connecting multiple branches through a spherical roof.