JPS6224790Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an intake manifold for an internal combustion engine.

In a multi-cylinder internal combustion engine, in order to improve output performance and fuel efficiency, it is necessary to evenly distribute the air-fuel mixture to each cylinder. In the intake manifold of a conventional internal combustion engine, the passages from the riser part 1 to the branch ports 3, 4, 5, and 6 via the curved passage part 2 were curved at an obtuse angle in the curved passage part 2; There was a tendency for a large amount of the air-fuel mixture flowing through the outer peripheral side to flow into the #1 and #4 branch ports 3 and 6 on the outer peripheral side. However, #1, #2, #3, and #4 branch ports are the first, second, and third cylinders, respectively, which are arranged in series from one end of the internal combustion engine to the other end.
The cylinder shows a branch port connected to the fourth cylinder (the same applies below). Also, during a cold start, some fuel that is not sufficiently atomized becomes liquid and flows inside the intake manifold, but due to inertia, a large amount of liquid fuel tends to flow toward the #1 and #4 branch ports 3 and 6. However, the fuel is blown toward the #1 and #4 branch ports 3 and 6 by the flow of the air-fuel mixture directed toward the #1 and #4 branch ports 3 and 6, making the fuel distribution even more uneven. I tended to.

An object of the present invention is to provide an intake manifold that not only equalizes the distribution of the air-fuel mixture to each cylinder, but also helps equalize the distribution of liquid fuel by equalizing the distribution of the air-fuel mixture. This is the purpose.

In order to achieve this object, the intake manifold for an internal combustion engine of the present invention is provided with a restriction that narrows the cross section of the passage from the side at a portion where the intake manifold enters the curved passage from the riser. This throttle is usually provided on the outer circumferential wall side of the passage cross section so as to protrude inwardly, but it may be provided on the inner circumferential wall side as well so as to protrude toward the outer circumference, if necessary. .
When the air-fuel mixture flows through the intake manifold configured in this way, it is throttled by the throttle section and the flow speed increases.
Atomization is promoted and the mixture is evenly distributed between each cylinder. In addition, the flow of liquid fuel is directed inward by the throttle on the outer peripheral wall side, making it difficult for liquid fuel to adhere to the outer peripheral wall, and strengthening the direction toward the #2 and #3 branch ports, which had previously been difficult to flow. I was hit,
Even distribution of liquid fuel is also improved.

Hereinafter, preferred embodiments of the intake manifold for an internal combustion engine according to the present invention will be described with reference to the drawings.

2 and 3 show an intake manifold according to a first embodiment of the present invention. In the figure, 10 is an intake manifold, which is roughly divided into a riser part 11 that changes the air-fuel mixture flowing from the carburetor from a vertical flow to a horizontal flow and heats it during warm-up;
#1 to #4 branch ports 13, 14, 15, 16 that branch the flow from the curved passage portion 12 and guide it to each cylinder. It consists of.

Of these, the riser portion 11 has an opening 17 on the top surface, and in the illustrated example, the opening 17 is an opening 17a communicating with the primary side of the dual carburetor and an opening 17b communicating with the secondary side. It is a pothole shaped hole. The bottom surface of the riser section 11 extends horizontally, and fins are formed on the back side of the bottom surface so that the exhaust gas flowing through the exhaust manifold during warm-up comes into contact with the fins and heats the bottom surface of the riser section 11. It's summery.

The curved passage section 12 extends outward on both left and right sides from the riser section 11 and slightly obliquely toward the cylinder head side, and curves therefrom toward the cylinder head side. The section that enters the curved passage section 12 from the riser section 11 has a substantially rectangular cross section, and a diaphragm 19 that protrudes toward the inner circumference is formed on the outer side wall 18 of the section. The wall surface of this throttle 19 smoothly connects to the widening part of the EGR gas inlet 20 at the front end, and the curved passage part 12 at the rear end.
It smoothly connects to the side wall surface of the wall, and has a mountain-like shape in the center that protrudes toward the inner circumference. The cross-sectional area of the throttle part is set to about 1.1 to 1.2 times the area of the intake valve passage so that the throttle part does not cause intake resistance.

The outer circumferential wall 21 of the curved passage section 12 protrudes outward on both left and right sides, so that the passage width in the horizontal plane of the curved passage section 12 is expanded. The outer peripheral wall 21 of the curved passage section 12 has a straight section 21a on the downstream side from the riser section 11, followed by a curved section 21b that curves toward the cylinder head, and further followed by a straight section 21c. The extension lines of the straight portions 21c of the pair of left and right outer peripheral walls 21 are inclined so as to intersect on the cylinder head side.

The branch ports 13, 14, 15, and 16 are arcuately curved and communicate with each port of the cylinder head. #1, #2 branch ports 13, 14,
A separator 22 is provided at the branch portions of the #3 and #4 branch ports 15 and 16 so as to extend to the curved passage portion 12 and protrude slightly upward from the lower surface of the passage.

In the case of the intake manifold configured as described above, in cold and cold weather, part of the fuel sucked from the carburetor is atomized and mixed with the intake air to form a mixture, and the remaining fuel that is not sufficiently atomized is It becomes a liquid or liquid droplet and flows inside the intake manifold 10 from the riser part 11 to the curved passage part 12, and from the curved passage part 12 to the #1 to #4 branch ports 13, 14,
It flows to 15 and 16. In this case, during warm-up, the back side of the bottom surface of the riser section 11 is heated by the exhaust gas, and vaporization of the liquid fuel is promoted.

When the air-fuel mixture flows into the curved passage section 12,
Since it is throttled by the throttle 19, the flow velocity increases, large liquid droplets of fuel become smaller, and atomization of the air-fuel mixture is promoted. In general, the more liquid fuel there is, or the larger the liquid particles are, the more the fuel will move to #1 and #4 due to inertia.
However, since the present invention promotes atomization, the fuel is evenly distributed to each cylinder.

In addition, the flow is directed to the inner circumferential side by the throttle 19 as shown by the streamlines in FIG. Deterioration of distribution properties due to an increase in the amount of fuel is prevented. In addition, the flow directed to the inner circumferential side by the throttle 19 provided on the outer circumferential wall 18 strengthens the directivity toward the #2 and #3 branch ports 14 and 15, and the flow of the liquid granular fuel to the #2 and #3 branch ports 14 and 15 is strengthened. Branch port 1
Increasing the rate of inflow to 4 and 15,
The liquid fuel flowing at the bottom of the passage is blown toward the #2 and #3 branch ports 14 and 15, greatly promoting uniform distribution of the liquid fuel to each cylinder.

In addition, part of the air-fuel mixture and liquid fuel that have passed through the throttle 19 and flowed into the curved passage 12 flow along the straight portion 21c of the outer peripheral wall 21 of the curved passage 12. 3 branch port 1
4 and 15 to promote uniform distribution of the air-fuel mixture.

FIG. 4 shows a curved passage inlet of an intake manifold according to a second embodiment of the present invention, and parts corresponding to the first embodiment are designated by the same reference numerals as in FIGS. 2 and 3 for explanation. Omitted. In FIG. 4, not only a throttle 19 is provided on the outer circumferential wall 18 but also a throttle 24 is provided on the inner circumferential wall 23 at a portion where the riser section 11 enters the curved passage section 12. The diaphragm 24 is provided at a position opposite to the diaphragm 19, and projects smoothly toward the outer circumference. The cross-sectional area of the passage narrowed by the throttle 19 and the throttle 24 is set to about 1.1 to 1.2 times the area of the intake valve passage so as not to cause intake resistance.

The intake manifold of the second embodiment configured as described above has the functions of the first embodiment, and the flow along the inner circumferential wall 23 is directed toward the center of the passage by the throttle 24 provided on the inner circumferential wall 23. This reduces the amount of fuel that adheres to the low-temperature inner circumferential wall 23 and re-liquefies it, and thereby equalizes the distribution of the air-fuel mixture. However, if the amount of protrusion of the throttle 24 is too large, the flow will be reduced to #1, #4 branch port 13,
It is desirable to make it small because it directs it to the 16 side.

As described above, when using the intake manifold for an internal combustion engine of the present invention, the throttle is provided on the outer circumferential wall of the portion that enters the curved passage from the riser part, so that the throttle connects the #2 and #3 ports to the #2 and #3 port sides. The flow of the droplet fuel can be directed, and the flow velocity of the flow can be increased to promote atomization of the droplet fuel, thereby promoting uniform distribution of fuel among the cylinders. In addition, the bottom of the passage where it enters the curved passage from the riser part has no restriction and is left as a flat surface, so if there is a restriction on the bottom of the passage, the liquid fuel that would accumulate on the bottom due to the restriction will be removed. The more the amount of fuel is reduced, the more atomization is promoted and the uniform distribution of fuel among the cylinders is promoted. In addition, since the outer circumferential wall of the curved passage has a part where the extensions of the tangent lines intersect on the cylinder head side, the air-fuel mixture whose flow velocity has been increased by the throttle is directed along the part of the curved passage. The fuel can be directed toward the #2 and #3 branch ports, which can promote uniform distribution of fuel between cylinders. By equalizing the air-fuel mixture distribution, it is possible to prevent plug smoldering due to oversupply of fuel and misfire due to undersupply, and it is possible to improve output, and ultimately improve fuel efficiency through this increase in output. This has the effect of being able to.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an intake manifold of a conventional internal combustion engine, FIG. 2 is a plan view of an intake manifold of an internal combustion engine according to a first embodiment of the present invention, and FIG.
FIG. 4 is a partial sectional view of the intake manifold of an internal combustion engine according to a second embodiment of the present invention. 10...Intake manifold, 11...Riser section,
12... Curved passage section, 13... #1 branch port,
14...#2 branch port, 15...#3 branch port, 16...#4 branch port, 18...outer peripheral side wall, 19...diaphragm, 21...curved passage portion outer peripheral wall,
21c...Outer peripheral wall straight portion, 22...Separator,
23...Inner peripheral wall, 24...Aperture.

Claims (1)

[Scope of utility model registration request] a riser section, a curved passage section connected to both downstream sides of the riser section and partially having an outer circumferential wall whose tangential extensions intersect on the cylinder head side, and #1 to #4 branch ports connected to the downstream side of the curved passage section. In an intake manifold for an internal combustion engine, the portion entering the curved passage from the riser part is formed into a substantially rectangular shape, and the outer circumferential wall extending in the vertical direction of the passage having a substantially rectangular cross section is provided with a wall for directing the flow of liquid fuel. A throttle is provided that protrudes toward the passageway having a substantially rectangular cross-section and narrows the passageway having a substantially rectangular cross-section from the side so that the direction is directed toward the #2 and #3 branch ports. An intake manifold for an internal combustion engine, characterized in that the bottom surface remains flat.