JP2605469Y2 - Exhaust manifold for 3-cylinder engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an exhaust manifold for a three-cylinder engine, which has low exhaust resistance and can reduce exhaust interference between cylinders.

[0002]

2. Description of the Related Art As shown in FIG. 1 or FIG. 4, a basic structure of an exhaust manifold of a three-cylinder engine to which the present invention is applied is a central part 2 of a horizontally oriented main pipe 1 and left and right ends 3. 4
The three exhaust guide pipes 5 are respectively extended rearward, and the inlet 6 of the exhaust inlet pipe 5 is connected to the exhaust port 1 of the three-cylinder engine E.
1, each of which has an exhaust outlet pipe 7 extending upward from a central portion 2 of the main pipe 1. As a prior art of this type, as shown in FIG. 4, there is one in which a main pipe 1 is formed of a cylindrical pipe, and the wall of the pipe is formed to have a uniform thickness and a smooth shape.

[0003]

In a three-cylinder engine of a type that collects exhaust gas at the upper center, an exhaust outlet pipe 7 where exhaust is concentrated is bent orthogonally to the main pipe 1.
Exhaust resistance at the exhaust outlet pipe 7 is large and exhaust is not smoothly discharged. In addition, the inertia of exhaust from one cylinder affects the exhaust from another cylinder and interferes with each other. In particular, in the exhaust inlet pipes 5.5 located at the left and right ends, the parent pipes 1 attempt to blow through each other toward one of the inlet pipes 5.
The directions of exhaust to the exhaust outlet pipe 7 are opposite to each other, and exhaust interference is likely to occur. As described above, since the back pressure of each cylinder increases due to the increase in exhaust resistance and exhaust interference, problems such as a decrease in charging efficiency and combustion efficiency occur. An object of the present invention is to provide an exhaust manifold of a type in which collective exhaust is collected at an upper central portion, and a technical problem is to exhaust the exhaust smoothly.

[0004]

The means for achieving the above object will be described below with reference to the drawings showing an embodiment. That is, in the present invention, in the exhaust manifold of the three-cylinder engine having the above-described basic structure, the exhaust outlet pipe 7 is provided with a forward exhaust at the center.
A portion of the central portion 2 of the parent tube 1 facing the exhaust outlet pipe 7 from below is defined as a lower inner peripheral surface 8 near the center, and the lower inner peripheral surface 8 near the center is raised immediately before the air inlet tube 5 . The center side flanks 10, 10 located on the left and right sides of the central portion of the exhaust inlet pipe 5 at the front side are formed in a mountain shape that rises smoothly from the left and right.

[0005]

[Effect] The central side portion 10.1 of the lower inner peripheral surface 8 near the center.
Since 0 is formed in a mountain shape that rises smoothly from the left and right, the exhaust gas from the exhaust inlet pipe 5 in the central portion 2 of the lower inner peripheral surface 8 near the center sandwiched between the mountains of the left and right side portions 10. It is guided by the concave surface and discharged to the upper exhaust outlet pipe 7. Exhaust gas from the left and right ends of the exhaust inlet pipe 5 is guided from the left and right ends 3.4 by an inclined surface that faces upward toward the center, and is discharged to the exhaust outlet pipe 7.

For this reason, the exhaust gas guided from each cylinder to the master pipe 1 is smoothly directed to the upper exhaust outlet pipe 7, so that the exhaust resistance to the exhaust outlet pipe 7 is reduced. Exhaust from the cylinders directed to the exhaust outlet pipe 7 is less likely to collide with each other, so that exhaust interference is also reduced. That is, the exhaust of the central cylinder can block the influence of exhaust from both ends at the left and right side portions 10. Further, since the exhaust gas of the two-end cylinders is guided to the exhaust outlet pipe 7 obliquely upward at the lower inner peripheral surface 8 near the center, it is necessary to blow through the wind tunnel of the main pipe 1 toward one of the inlet pipes 5. Can be suppressed.

[0007]

[Effect of the invention] (a). Exhaust manifold for three cylinder engine
Master tube that reduces exhaust interference in the field and improves filling efficiency
1, the exhaust gas flowing from the left exhaust inlet pipe 5
Is guided upward at the chevron on the left side of the side 10 near the center
And flows out to the exhaust outlet pipe 7, so that the exhaust
It is difficult to flow into the pipe 5 side and the right exhaust inlet pipe 5 side.
The exhaust gas flowing in from the exhaust pipe 5 on the right side is closer to the center.
The exhaust outlet is guided upward at the chevron on the right side of the side part 10.
Since it flows out to the pipe 7, the exhaust inlet pipe 5 at the center and the left
Hardly flows into the side exhaust inlet pipe 5 side. Center exhaust
The exhaust gas flowing in from the mouth pipe 5 is located at the side 10. 1 near the center.
Exhaust outlet pipe that is guided upward at the chevron on both left and right sides of 0
7, the exhaust pipe 5 on the left and the right
It is difficult to flow into the exhaust pipe 5 side. For this reason, three-cylinder
Exhaust interference in the engine exhaust manifold is reduced,
The filling efficiency is improved. This will improve engine output,
Improve fuel economy and reduce HC, CO, and carbon concentrations in exhaust
It can contribute to reduction.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of an exhaust manifold of a central central type, and FIG. 2 is a schematic perspective view of an exhaust system of a three-cylinder engine. As shown in FIG. 2, the exhaust port 11 is opened in the cylinder head 12 of the three-cylinder vertical engine E, and the exhaust port 11 is opened.
To the exhaust manifold M. Exhaust manifold M
As shown in FIG. 1 and FIG. 2, three exhaust inlet pipes 5 are respectively branched at right angles in the horizontal direction from a central part 2 of a horizontal parent pipe 1 and left and right end parts 3.4 thereof. Inlet 6 of exhaust inlet pipe 5
Are connected to the exhaust port 11 respectively, and the central portion 2
The exhaust outlet pipe 7 is led upward from the outlet to collect the collective exhaust at the upper center.

As shown in FIG. 1, the exhaust outlet pipe 7 has a central portion.
Upright in front of the forward exhaust pipe 5
You. A part of the central part 2 of the main pipe 1 facing the exhaust outlet pipe 7 from below is defined as a lower inner peripheral surface 8 near the center, and a front side of the central exhaust inlet pipe 5 in the lower inner peripheral surface 8 near the center. In position
When the parts separated toward the left and right ends 3 and 4 are set as the side parts 10 and 10 near the center, the side parts 10 are cast so as to form a chevron that rises smoothly from the left and right.
That is, the lower inner peripheral surface 8 near the center is raised in a mountain shape as it approaches the side portion 10 from the center portion, and the lower inner peripheral surface 8 is inclined downward as the distance from the side portion 10 to the left and right increases. For this reason, in the lower inner peripheral surface 8 near the center of the main pipe 1, there are formed two chevrons which are separated from left and right with the side part 10 as a crest. Is formed in a recessed surface along the lower part of the outlet 12 of the first member. In addition, the side 1 of the mountaintop
The ridge 14 deviating from 0 toward both ends 3.4 is continuous with the lower inner peripheral surface 15 near both ends 3.4 of the main tube 1.

Therefore, the function of the exhaust manifold will be described. Since the lower inner peripheral surface 8 near the center of the main pipe 1 is formed in a continuous mountain shape, the exhaust from the exhaust inlet pipe 5 in the central portion 2 is left and right. It is guided by the concave surface 13 sandwiched between the mountains of the right side parts 10 and is discharged to the upper exhaust outlet pipe 7. Exhaust gas from the exhaust inlet pipe 5 at one end is guided by the inclined surface 14 facing upward toward the other end, and is exhausted to the exhaust outlet pipe 7. For this reason, the exhaust gas guided from each cylinder to the master pipe 1 is smoothly directed to the upper exhaust outlet pipe 7, and the exhaust resistance to the exhaust outlet pipe 7 is reduced, and the exhaust gas is less likely to collide with each other. Interference is also reduced. For this reason, the back pressure of each cylinder is reduced, and the charging efficiency and the like are improved.

As described above, the technique of reducing exhaust resistance and the like by directing exhaust gas from each cylinder to the exhaust outlet pipe 7 can also be applied to a manifold M that collects exhaust gas at one end of a main pipe. That is, as shown in FIG. 3, an exhaust outlet 20 is opened at the left end 22 of the main pipe 1, and the three exhaust inlet pipes 5 are tilted leftward toward the right end 23 of the main pipe 1 in a curved inclined shape. To form the exhaust manifold M,
The outlets 12 of the exhaust inlet pipes 5 on the left and the center are projected into the flow space 21 of the main pipe 1 so as to be curved and inclined toward the left end 22. In the manifold M having this structure, the exhaust gas from each cylinder is smoothly directed to the exhaust outlet 20 by the outlet port 12 and is smoothly led out to the main pipe 1. Exhaust is more easily exhausted as compared to a conventional one-end concentrated type manifold (see virtual line P) that only branches in a shape.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an exhaust manifold of a central central type.

FIG. 2 is a schematic perspective view of an exhaust system of a three-cylinder engine.

FIG. 3 is a longitudinal sectional view of an exhaust manifold of a one-end concentrated type.

FIG. 4 is an equivalent view of FIG. 1 showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Central part of main pipe 21 1 Left end of 31 4 Right end of 1 5 Exhaust inlet pipe 6 Inlet of 5 7 Exhaust outlet pipe 8 Lower inner peripheral face near the center of 1 8 Side piece near the center of 8 11 Exhaust port E 3-cylinder engine M Exhaust manifold

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kozo Yoshida 64 Ishizu-Kitacho, Sakai-shi, Osaka Kubota Sakai Works Co., Ltd. (Int.Cl. ⁷ , DB name) F01N 7/10 F02B 75/18

Claims (1)

(57) [Scope of request for utility model registration] 1. Three exhaust inlet pipes (5) are respectively extended rearward from a central part (2) of a horizontal parent pipe (1) and left and right end parts (3) and (4) thereof to exhaust air. The inlet port (6) of the inlet pipe (5) communicates with the exhaust port (11) of the three-cylinder engine (E), respectively.
In an exhaust manifold of a three-cylinder engine in which an exhaust outlet pipe (7) is drawn upward from a central part (2) of (1), the exhaust outlet pipe (7) is directly connected to a central forward-facing exhaust inlet pipe (5).
A part facing upward from the bottom of the central part (2) of the main pipe (1) facing the exhaust outlet pipe (7) is defined as a lower inner peripheral surface (8) near the center, and the lower inner peripheral part near the center is raised. Surface (8), in front of the central exhaust inlet pipe (5)
Middle side portion located on both left and right sides of the side position (10) - (1
An exhaust manifold for a three-cylinder engine, wherein 0) is formed in a chevron shape that rises smoothly from the left and right.