JPS6129960Y2 - - Google Patents

Description

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

Generally, in an internal combustion engine, in order to avoid plug smoldering and misfire, improve output performance, and improve fuel efficiency, it is necessary to distribute the air-fuel mixture evenly to each cylinder. Especially in cold regions, when the engine is not warmed up sufficiently, the fuel is not vaporized sufficiently, so the fuel flows through the intake manifold in liquid form or in the form of liquid droplets, causing liquid fuel to flow through each cylinder. It is necessary that the equal distribution be carried out smoothly.

In a conventional intake manifold, as shown in FIG.
The outer circumferential wall 3 of the cylinder head is formed so that its extension line 4 intersects the cylinder head on the opposite side. Therefore, the liquid fuel flowing with inertia toward the outer circumferential side is directed to #1 and #4 of the cylinder head. A large amount of liquid fuel flows into the branch ports 6 and 7 heading toward the cylinders, and a small amount flows into the branch ports 8 and 9 heading toward the #2 and #3 cylinders, resulting in uneven distribution of liquid fuel to each cylinder.
Various measures have been taken to distribute this evenly. As one of the countermeasures against this problem, the applicant has made the outer circumferential wall 3 of the curved passage section 2 on both sides of the riser section 1 extend outward as shown in FIG.
By crossing the extension lines 4 on the cylinder head side and allowing part of the mixture and liquid fuel to flow along the outer peripheral wall, more of the liquid fuel flow is directed toward the #2 and #3 branch ports 8 and 9. An intake manifold has been proposed in which the fuel is evenly distributed to each cylinder.

The present invention aims to equalize the distribution of fuel to each cylinder while maintaining the #2 and #3 branch port orientation by the outer circumferential wall of the intake manifold curved passage in the above proposal. The purpose is to further improve the uniformity of distribution to each cylinder.

In order to achieve this purpose, in the intake manifold for an internal combustion engine of the present invention, the extension lines of the outer peripheral walls of the curved passages on both sides of the riser part intersect on the cylinder head side, and the #1 branch port and the #1 branch port 2
The port branch point of the branch port and the port branch points of the #3 branch port and #4 branch port bisect the passage width in the direction parallel to the intake manifold mounting surface of the curved passage section immediately before transitioning to the branch port section, respectively. It is closer to the #1 and #4 branch ports than the line. With this passage configuration, the liquid fuel flowing through the curved passage easily flows into the #2 and #3 branch ports, and due to the outer circumferential wall of the curved passage oriented toward the cylinder head, the liquid fuel flows toward the #2 and #3 branch ports. Since the directed air-fuel mixture further strengthens the direction of the liquid fuel toward the #2 and #3 branch ports, the liquid fuel is effectively distributed evenly during cold starting.

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.

FIG. 3 shows an intake manifold according to an embodiment of the present invention. In the figure, 10 is the intake manifold,
Broadly speaking, there is a riser section 11 that changes the air-fuel mixture flowing from the carburetor from a vertical flow into a horizontal flow and heats it during warm-up, and a curved passage connected to both sides of the riser section 11 that bends the flow toward the cylinder head. portion 12, and the flow from the curved passage portion 12 is branched near the port branch portions 13, 14 to form #1, #2,
Branch ports 15 and 1 leading to each cylinder #3 and #4
It consists of 6, 17, and 18.

Of these, the riser portion 11 is opened upward, and in the illustrated example, the opening 19 is a bell-shaped opening 19a communicating with the primary side of the dual carburetor and an opening 19b communicating with the secondary side. It is shaped like a 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 portion 12 extends in a straight line from the riser portion 11 to both left and right sides and toward the cylinder head side, and curves from there to the cylinder head side. In this curved portion, the outer circumferential wall extends outward on both the left and right sides, so that the curved passage portion 1
The passage width in the horizontal plane of 2 is enlarged. The outer circumferential wall 24 of the curved passage section 12 has a straight section 20a on the downstream side from the riser section 11, followed by a curved section 20b that curves toward the cylinder head side, and further followed by a straight section 20c. The extension line 21 of the straight portion 20c of the pair of left and right outer peripheral walls 20 is
They are inclined so as to intersect on the cylinder head side. Further, the upper surface 22 of the curved passage section 12 has a curved line 2
3, the outer circumferential portion is inclined and narrowed so as to descend toward the outer circumferential side. moreover,
Outer peripheral wall 20 of curved passage section 12, passage and lower passage surface 2
4, an inclined surface 25 is provided that rises diagonally outward from the lower surface 24 of the passage, and a curve 26 indicates an intersection line between this inclined surface 25 and the lower surface 24 of the passage. In this way, the curved passage section 12 is constricted at its outer circumference, but since the outer circumferential wall 20 protrudes outward, the cross-sectional area of the passage itself is not reduced, and the constriction or inclined surface of the upper surface acts as a flow resistance. Never.

The branch ports 15, 16, 17, and 18 are arcuately curved and communicate with each port of the cylinder head. The branch ports 15, 16, 17, and 18 are each smoothly connected to the left and right curved passage portions 12, and have a circular or nearly circular cross-sectional shape at the port exit portion. In addition, a port branch point 13 between #1 branch port 15 and #2 branch port 16
is the #1 branch port 15 from the bisector 28 of the passage width in the direction parallel to the intake manifold mounting surface 27 of the curved passage part 12 immediately before the transition part from the curved passage part 12 to the branch ports 15 and 16. It is placed as close to the side as possible. However, #1 branch port 1
The aperture is close enough that it doesn't have an aperture of 5. Similarly, #3 branch port 17 and #4 branch port 18
The port branch point 14 between the curved passage section 12 and the branch port 17 and 18 is located just before the transition section from the curved passage section 12 to the branch ports 17 and 18, beyond the bisector 29 of the passage width in the direction parallel to the intake manifold mounting surface 20 of the curved passage section 12. It is placed as close to #4 branch port 18 as possible.

On the bottom surface 24 of both the vicinity of the branch point 13 of the branch ports 15 and 16 and the curved passage section 12 connected thereto,
Further, the passage lower surface 24 of both the vicinity of the branch point 14 of the branch ports 17 and 18 and the curved passage part 12 connected thereto.
, the curved passage section 12 starts from the vicinity of the branch points 13 and 14.
A separator 30 extending inward is provided integrally with the passage lower surface 24 and slightly protrudes upward from the passage lower surface 24. The separator 30 extends approximately to the center of the curved passage portion 12, and its starting point 31 is located on the inner peripheral side of the port branch points 13 and 14, on the side of the #2 and #3 branch ports 16 and 17.

In the case of the intake manifold configured as described above, during cold weather, part of the fuel drawn from the carburetor mixes with the intake air to form a mixture, and the remaining fuel that is not sufficiently vaporized becomes liquid. , inside the intake manifold 10 from the riser part 11 to the curved passage part 12,
Further, from the curved passage section 12, branch ports 15,1
It flows to 6, 17, 18. 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.

The liquid fuel flows on the lower surface 24 of the passage under its own weight, but in the curved passage part 12, part of the flow is bent by the separator 30 and flows along the separator 30, and flows into the #2 and #3 branch ports 16 and 17. be done. Further, the liquid fuel and the air-fuel mixture flowing outward over the separator 30 collide with the outer circumferential wall 20, the flow is bent along the outer circumferential wall 20, and the straight portion 20c of the outer circumferential wall is directed toward the cylinder head. 2 and #3 branch ports 16 and 17 and flow out.

The liquid fuel and air-fuel mixture flowing strongly toward the #2 and #3 branch ports 16 and 17 are caused by the fact that the port branch points 13 and 14 are as close to the #1 and #4 branch ports 15 and 18 as possible. The fuel flow that tends to flow into the #2 and #3 branch ports 16 and 17 and which conventionally tends to flow toward the #1 and #4 branch ports 15 and 18 is more evenly distributed to each cylinder.

As mentioned above, the distribution of liquid fuel to each cylinder is equalized, but in general, the amount of intake air itself is determined by the cylinder capacity and the amount of intake air is almost constant for each cylinder, so the distribution of liquid fuel to each cylinder is When the mixture ratios of the cylinders are equalized, the mixture ratios of each cylinder are also equalized accordingly.

As described above, when the present invention is applied to the intake manifold of an internal combustion engine, the extension lines of the outer circumferential wall of the curved passage section are made to intersect on the cylinder head side, and the port branch points are moved toward the #1 and #4 ports. Therefore, it is possible to promote uniform distribution of liquid fuel to each cylinder during a cold start, thereby avoiding smoldering plugs in #1 and #4 cylinders and misfires in #2 and #3 cylinders. This has the effect of improving output performance through uniform distribution of the air-fuel mixture and equalization of the mixture ratio, and ultimately improving fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the intake manifold of a conventional internal combustion engine, FIG. 2 is a schematic diagram of the intake manifold of an internal combustion engine already proposed by the applicant, and FIG. 3 is a plan view of the intake manifold of the present invention. FIG. 4 is a cross-sectional view of the intake manifold of FIG. 3 taken along the - line. 10...Intake manifold, 11...Riser section,
12... Curved passage part, 13, 14... Branch part, 1
5...#1 branch port, 16...#2 branch port, 17...#3 branch port, 18...#4 branch port, 20...curved passage portion outer peripheral wall, 20c...
Outer peripheral wall straight section, 28...bisector of curved passage section,
30...Separator.

Claims (1)

[Scope of utility model registration request] In an intake manifold for an internal combustion engine, which includes a riser part, curved passage parts on both sides of the riser part, and #1 to #4 branch ports connected downstream of the curved passage part, the extension line of the outer peripheral wall of the curved passage part is on the cylinder head side. The curved passage section is formed so as to intersect with each other, and the port branch points of #1 branch port and #2 branch port and the port branch points of #3 branch port and #4 branch port are respectively transferred to the curved passage section immediately before transitioning to the branch port section. An intake manifold for an internal combustion engine, characterized in that the intake manifold is located closer to the #1 and #4 branch ports than the bisector of the passage width in the direction parallel to the intake manifold mounting surface.