JP3089678B2 - Exhaust manifold for internal combustion engine - Google Patents

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, which is applied to an internal combustion engine having a plurality of cylinders, for example, four cylinders.

[0002]

2. Description of the Related Art In an internal combustion engine having a plurality of cylinders,
It is desirable that interference does not occur in the exhaust of each cylinder. That is, the occurrence of interference leads to a reduction in output and a reduction in fuel consumption. This will be described with reference to FIGS. 9 and 10 showing a conventional exhaust manifold. This exhaust manifold 1 is for a four-stroke in-line four-cylinder engine, and is connected to four mufflers and tail pipes (not shown) from four branch pipes 2, 3, 4, and 5 corresponding to respective cylinders of a cylinder block (not shown). It merges with the collecting pipe 6. Reference numerals 7, 8, 9 and 10 denote mounting flanges for a cylinder block (not shown), and reference numeral 11 denotes a boss for fixing the collecting pipe 6.

In this exhaust manifold 1, the exhaust gas entering the branch pipes 2, 3, 4, and 5 from the respective cylinders of the four-cylinder internal combustion engine gathers in the collecting pipe 6 and travels toward the muffler side. The state is not always uniform. That is, assuming that a line passing through the center of the collecting pipe 6 is e, a line a passing through the center of the branch pipe 2 for the first cylinder and a line b passing through the center of the branch pipe 3 for the second cylinder are shown in FIG. As shown in the drawing, the pipe is connected at a distance from the collecting pipe 6, and the bent state is formed at that portion. On the other hand, the line c passing through the center of the branch pipe 4 for the third cylinder is connected to the line e almost linearly. 4th
A line d passing through the center of the cylinder branch pipe 5 is connected to a line e passing through the center in the immediate vicinity of the collecting pipe 6 if it is bent. Then, as shown in FIG. 10, even when viewed from the side, only the line a passing through the center of the branch pipe 2 for the first cylinder draws a different trajectory from the other lines b, c, d.

Since the above-mentioned internal combustion engine has four cylinders, the theoretical combustion sequential crank angle is an angle obtained by dividing 720 degrees by 4, that is, 180 degrees. However, since the exhaust stroke in a normal internal combustion engine is 180 degrees or more, exhaust interference may occur depending on the shape of the exhaust manifold. In FIG. 9, when the combustion order is the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder, the first cylinder and the second cylinder, and the third cylinder and the fourth cylinder emit the exhaust gas for the above-described reason. Interference will occur. This is because the stroke of the normal internal combustion engine is such that the intake stroke starts before the top dead center of the piston and ends after the bottom dead center, and the subsequent compression stroke ends the intake stroke and the start angle of the intake stroke. The expansion stroke is performed to the same angle, the expansion stroke starts at the same angle as the start of the intake stroke and ends before bottom dead center, and the exhaust stroke is performed from the end of this expansion stroke to after passing the piston top dead center. by.

[0005]

SUMMARY OF THE INVENTION The present invention provides an exhaust manifold in which interference between cylinders is prevented by changing the shape of a branch pipe portion, and an exhaust sensor mounting position is also improved. It is something to offer.

[0006]

The present invention SUMMARY OF] as a means for solving the above problems, an internal combustion engine having a plurality of cylinders
In the exhaust manifold, install branch pipes corresponding to each cylinder.
And a single collecting pipe is provided downstream of the branch pipe.
Single merging of the exhaust flowing through the branch pipe into the pipe
A point is provided, and each branch pipe intersects at a certain angle with respect to the center line of the collecting pipe , and each adjacent branch pipe intersects at a certain plane angle.

[0007]

The exhaust gas flowing through each branch pipe has such a structure.
Single unit with a single junction connected to a branch pipe
Provide in the pipe so that the exhaust conditions of each cylinder are constant.
You. For this reason, each branch pipe has a certain condition, that is, each branch pipe.
Is a fixed angle to the center line of the collecting pipe (the same divergence angle
), And each adjacent branch pipe is constant
Condition, that is, they should intersect at a certain plane angle.
You. In this way, exhaust interference occurs between the cylinders.
As a result, the exhaust from each cylinder flows uniformly toward the collecting pipe, and the exhaust conditions of the cylinder become constant. Therefore, the combustion in each cylinder becomes uniform. In addition, variations in the emission of various harmful components are reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to FIGS. 1 and 2 corresponding to FIGS. 9 and 10, FIG. 3 as viewed from above in FIG. FIG. 6 showing the cross section, FIG.
FIG. 7 showing a B section and FIG. 8 showing a CC section will be described. As is apparent from these figures, the exhaust manifold 1 of the present invention has all the branch pipes 2, 3,
All of 4 and 5 are connected at the root of a single collecting pipe 6. As a result, each branch pipe 2, 3, 4,
5 line a passing through the center of the, b, c, d in root vicinity of the collecting pipe 6, 1 point to a line e passing through the center of the collecting pipe 6 (merge
They will meet at point Q) .

FIG. 4 is an enlarged view of a main part of FIG. 1, and FIG. 5 is an enlarged view of a main part of FIG. As can be seen from these figures, the junction Q of each of the branch pipes 2 , 3 , 4 , and 5 to the collecting pipe 6 is one point, and each of the branch pipes 2, 3 around this junction Q is , 4 and 5, the plane angle viewed from above is 90 degrees. Also, at the position where the branch pipes 3 and 5 of the second and fourth cylinders appear to overlap, the spread angle of the branch pipes 2 and 4 of the first and third cylinders viewed from the lateral direction (see FIG. 4)
And the divergence angles (see FIG. 5) of the branch pipes 3, 5 of the second and fourth cylinders as viewed from the side at a position where the branch pipes 2, 4 of the first and third cylinders appear to overlap each other. The angle is α.

According to the exhaust manifold 1 configured as described above, exhaust from each cylinder passing through the first to fourth branch pipes 2 to 5 flows uniformly toward the collecting pipe 6. Thus, the exhaust conditions of each cylinder are made uniform, so that the combustion of each cylinder becomes uniform. In connection with this, the emission variation of various harmful components is reduced.

In an internal combustion engine, an exhaust gas sensor (O ₂ sensor) is mounted on an exhaust manifold, and the fuel system is controlled in accordance with the detection result to increase the purification efficiency of the three-way catalyst. Therefore, it is necessary to attach an exhaust sensor to the exhaust manifold 1 (see Japanese Utility Model Publication No. 58-36810). In FIG. 1, reference numeral 12 denotes an exhaust sensor mounting boss for mounting an exhaust sensor (not shown). An exhaust sensor is mounted on the exhaust sensor mounting boss 12 so as to detect the O ₂ concentration in the exhaust. Has become. The position of the mounting boss 12 is determined by the merging of the branch pipes 2 , 3 , 4 , and 5 .
A small distance (about 0 to 20 mm) downstream of point Q is provided. By mounting the exhaust sensor at this position, all exhaust gas discharged from each cylinder touches this exhaust sensor. Therefore, the O ₂ concentration can be detected for all cylinders under exactly the same conditions. As a result, measured values during exhaust of all cylinders become uniform.

[0012]

As described above, the present invention is applicable to each cylinder.
From a single junction where the exhaust flowing through the branch pipe merges from
Provided in a single collecting pipe connected to the pipes, each branch pipe
Constant angle to center line of joint pipe (same spread angle)
At the same time, and make sure that adjacent branch pipes
Since it is configured so as to intersect the plane angle, without the exhaust interference occurs between each cylinder, exhaust manifold pipe
Towards, so as to Komu flow uniformly. By this
The exhaust conditions of the cylinders can be kept constant,
Can be unified. Therefore, there is an advantage that the output is improved and the fuel efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a front view of one embodiment of the present invention.

FIG. 2 is a side view of FIG. 1 viewed from the right.

FIG. 3 is a plan view of FIG. 1 viewed from above.

FIG. 4 is an enlarged front view of a main part of FIG. 1;

FIG. 5 is an enlarged front view of a main part of FIG. 2;

FIG. 6 is a sectional view taken along line AA of FIG. 1;

FIG. 7 is a sectional view taken along the line BB of FIG. 1;

FIG. 8 is a sectional view taken along line CC of FIG. 1;

FIG. 9 is a front view of a conventional exhaust manifold.

FIG. 10 is a side view of FIG. 9 viewed from the right.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Exhaust manifold 2 Branch pipe 3 Branch pipe 4 Branch pipe 5 Branch pipe 6 Collecting pipe Q junction

Claims (1)

(57) [Claims] 1. An exhaust manifold for an internal combustion engine having a plurality of cylinders.
In Rudo, provided the branch pipe for each cylinder, the
A single collecting pipe is provided downstream of the branch pipe, and the
A single junction where the exhaust flowing through the branch pipe is joined,
An exhaust manifold for an internal combustion engine, wherein each branch pipe intersects at a certain angle with respect to the center line of the collecting pipe, and each adjacent branch pipe intersects at a certain plane angle.