JPH022935Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) This invention relates to an intake manifold for a multi-cylinder internal combustion engine that distributes a mixture from a common fuel supply system to each of a plurality of cylinders.

(Technical Background) The intake manifold of an internal combustion engine supplies a mixture of fuel and air to the combustion chambers of each cylinder in the cylinder head in the fuel supply system. In the case where the air-fuel mixture is distributed and supplied to each of a plurality of cylinders from the common fuel supply system, it is necessary that the air-fuel mixture is uniformly distributed and supplied to each cylinder.

(Prior Art and Problems) Conventionally, the intake manifold of an internal combustion engine generally has a round cross-sectional shape from the viewpoint of being a passage for atomized fuel.

However, with this kind of passage structure, there is not much of a problem when the engine is in a high temperature state;
If the fuel is not completely atomized and some liquid remains at low temperatures, the ability to distribute fuel to each cylinder will deteriorate.

In other words, when the engine is at a low temperature, fuel atomization is not promoted, and much of the fuel flows in liquid form at the bottom of the passage and flows into the combustion chamber from each intake port in the cylinder head. In the case of a cross-sectional structure, the liquid fuel has a large degree of freedom in the flow direction, and it is difficult to uniformly distribute and supply the liquid fuel to each intake port. As a result, complete combustion in each combustion chamber becomes difficult, resulting in the emission of harmful exhaust gases, a decrease in output, and a decrease in fuel efficiency. In particular, the flow direction of liquid fuel is easily affected by centrifugal force and the like, and it is even more difficult to ensure uniform distribution and supply to each cylinder when the vehicle is turning.

Furthermore, in order to improve the above-mentioned problems in the fuel distribution system, a technique has been proposed in which a groove is formed in the bottom of the passage of the intake manifold through which liquid fuel flows, as disclosed in Japanese Utility Model Publication No. 52-21399. However, this type has the disadvantage that the groove changes its shape rapidly in the direction in which the liquid fuel flows, which increases suction resistance.
Practically unfavorable.

(Purpose of the invention) Therefore, in view of the above-mentioned problems, this invention is capable of distributing and supplying liquid fuel without being atomized to each cylinder almost uniformly, and in the distribution supply. It is an object of the present invention to provide an intake manifold for a multi-cylinder internal combustion engine that has a structure in which an increase in intake resistance can be prevented by gradually changing the shape of a passage.

(Structure of the invention) In order to achieve the above object, this invention supplies the air-fuel mixture to each cylinder in the intake manifold of a multi-cylinder internal combustion engine that distributes the air-fuel mixture from a common fuel supply system to each of a plurality of cylinders. The inner bottom of the passageway is formed into a substantially V-shaped cross section that smoothly continues with the inner wall of the passageway, and the V-shaped angle of the inner bottom is set to gradually become smaller toward the downstream side in the intake direction. This is what I did.

(Embodiment of the invention) Hereinafter, an embodiment of the invention will be described in detail based on FIGS. 1 and 2.

The intake manifold 1 shown in FIG. 1 is for a four-cylinder internal combustion engine. In this intake manifold 1, the primary intake passage 3 and the secondary intake passage 4, which are formed on the center line of the flange 2 for attaching the carburetor, have left and right first branches that branch left and right from the first branch part 5 on the downstream side in the intake direction. The passage 6 and the second branch part 7 downstream of each of the left and right first branch passages 6.
It further has left and right second branch passages 8 that branch left and right.

These first branch passages 6 and second branch passages 8
are in communication with each other, and the air-fuel mixture flowing from the primary intake passage 3 or the secondary intake passage 4 is first divided at the first branch part 5 as shown by the arrow in the figure, and then flows into the left and right first branch passages 6. The air-fuel mixture flows through the respective second branch passages 8 and flows downstream, and is further divided at the respective second branch portions 7 and flows through the left and right second branch passages 8. The air-fuel mixture flowing through the respective second branch passages 8 is connected to a flange 9 (not shown). It is supplied to each combustion chamber through the in-cylinder intake port of each cylinder of the engine.

The inner bottoms of each of the first branch passages 6 and each of the second branch passages 8 have a substantially V-shaped cross section as shown in FIGS. 3 to 6, and the V-shaped angle θ is equal to They are set to become smaller as they go downstream. Further, the inner bottom portion having a substantially V-shaped cross section is continuously formed from the first branch portion 5 to just before the downstream end (flange 9) of each of the second branch passages 8.

That is, approximately the center (-
), the V-shaped angle θ ₁ (e.g.
165°), and the first branch passage 6 downstream from it
As shown in FIG. 4, near the downstream end (- part) of the V-shaped angle _{θ 2 (} for example,
155°), and the V-shaped angle θ ₃ (for example, 150°) is smaller than the V-shaped angle θ ₂ as shown in FIG. ,
Approximately the center of the second branch passage 8 downstream from it (-
As shown in FIG. 6, the V-shaped angle θ ₄ is smaller than the V-shaped angle θ ₃ (for example, 115°).
On the other hand, in each of the second branch passages 8 downstream from this point, the V-shaped angle θ gradually approaches 180°, and near the opening end of the flange 9 it is approximately 180°, that is, horizontal, as shown in FIG. .

According to the intake manifold 1 of the embodiment having such a structure, when the engine is at a low temperature, the air flows from the carburetor (not shown) to the left and right first branch passages via the primary intake passage 3 or the secondary passage 4 and the first branch part 5. When the non-atomized liquid fuel flowing into the air-fuel mixture 6 flows from each first branch passage 6 toward each second branch passage 8 as described above, the liquid fuel flows through each first branch passage 6 and each second branch passage 8. 2 branch passage 8
At the same time, the liquid is collected at the center of the inner bottom and flows through the center. In this case, since the inner bottom is shaped to have flow directionality in the same direction as the fuel intake direction, the liquid fuel that flows from each first branch passage 6 to each second branch passage 8 is approximately uniform. This makes it possible to make the air-fuel ratio of each cylinder substantially the same. In particular, like the illustrated intake manifold 1,
When the air-fuel mixture from a common fuel supply system is distributed and supplied to a plurality of cylinders, it is possible to divide the mixture at a plurality of branch parts (the first branch part 5 and the second branch part 7), which has the effect of equalizing the air-fuel ratio. expensive.

In addition, the V-shaped angle θ becomes smaller toward the downstream side of each passage, and the V-shape is formed smoothly from the side wall of the intake passage to the entire inner bottom wall, thereby preventing a sudden change in the cross-sectional passage shape. Since this avoids a sudden increase or change in passage resistance, smooth air-fuel mixture intake is achieved, and an improvement in output can be achieved while ensuring a uniform air-fuel ratio.

(Effects of the invention) As explained above, according to the intake manifold of a multi-cylinder internal combustion engine of the present invention, the intake manifold of a multi-cylinder internal combustion engine that distributes the air-fuel mixture from a common fuel supply system to each of a plurality of cylinders. , the inner bottom of the passage supplying the air-fuel mixture to each cylinder is formed into a substantially V-shaped cross section that smoothly continues with the inner wall of the passage, and the V-shaped angle of the inner bottom faces toward the downstream side in the intake direction. Since the setting is made gradually smaller as the temperature increases, it is possible to give flow directionality to the fuel that flows in liquid form when the engine is at low temperature without increasing the intake resistance (passage resistance). It becomes possible to distribute and supply liquid fuel substantially uniformly to each cylinder even when the vehicle turns, which may affect the engine, and improves the fuel distribution function when the engine is at low temperature.

In addition, the V-shaped angle at the inner bottom of the passage is set to become smaller as it goes downstream in the intake direction, so that the fuel that adheres to the inner circumferential surface of the passage in the upstream direction of the intake direction is not accumulated and is In the downstream direction in the intake direction, the movement of the fuel that tends to spread due to vehicle fluctuations is suppressed, and the fuel can be sent smoothly into each cylinder.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the intake manifold of a multi-cylinder internal combustion engine according to this invention, FIG. 2 is a front view of the same, and FIG. 3 is a sectional view taken along the line - in FIG.
Figure 4 is a cross-sectional view taken along the - line in Figure 1, Figure 5 is a cross-sectional view taken along the V-V line in Figure 1, and Figure 6 is a cross-sectional view taken along the line V-V in Figure 1.
It is a sectional view taken along the - line in the figure. 1... Intake manifold, 2... Carburetor mounting flange, 3... Primary intake passage, 4...
...Secondary intake passage, 5...First branch, 6...
...First branch passage, 7...Second branch, 8...Second
Branch passage, θ ₁ to θ ₄ ... V-shaped angle.

Claims (1)

[Claims for Utility Model Registration] 1. In an intake manifold of a multi-cylinder internal combustion engine that distributes a mixture from a common fuel supply system to each of a plurality of cylinders, the inner bottom of the passage that supplies the mixture to each of the cylinders is It is characterized in that it is formed into a substantially V-shaped cross section that is smoothly continuous with the inner wall of the passage, and the V-shaped angle of the inner bottom is set to become gradually smaller toward the downstream side in the intake direction. Intake manifold of multi-cylinder internal combustion engine. 2. The intake manifold is composed of a first branch passage branching from the common fuel supply system and a second branch passage branching from each of the first branch passages, and the substantially V-shaped inner bottom portion is formed of a first branch passage branching from the common fuel supply system and a second branch passage branching from each of the first branch passages. The intake manifold for a multi-cylinder internal combustion engine according to claim 1, wherein the intake manifold is continuously formed from the branching part of the branching passage to just before the downstream end of each of the second branching passages. .