JPS6033333Y2 - Internal combustion engine intake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for a multi-cylinder internal combustion engine, which distributes a mixture from a horizontal carburetor to each cylinder at a substantially equal air-fuel ratio.

Conventional intake manifolds, which distribute the air-fuel mixture from the carburetor to each cylinder, connect the intake passages to each cylinder horizontally in different directions to the collecting part where the carburetor is attached.
Also, since the length of the intake passages to each cylinder is different, the flow from the gathering part to each intake passage becomes uneven, so the air-fuel mixture from the carburetor cannot be distributed equally to each cylinder, and the air-fuel mixture to each cylinder becomes uneven. The air-fuel ratio and charging efficiency are not the same.

Therefore, combustion in each cylinder becomes uneven, resulting in an increase in vibration and noise of the engine.

In this case, if the carburetor is vertical, the air-fuel mixture flowing down from the carburetor is turned horizontally at the gathering part of the intake manifold, and at this time, the air-fuel mixture is subjected to an agitating action and the flow velocity is reduced once, then Since the air-fuel mixture is distributed to each intake passage, there is an advantage that the amount of air-fuel mixture distributed to each cylinder and the air-fuel ratio can be made fairly uniform.

However, in the case of a horizontal carburetor, the air-fuel mixture flows into the manifold gathering part with directionality in the horizontal direction, so like a conventional intake manifold,
If the intake passages are simply branched horizontally in a three-pronged or four-pronged configuration, it is difficult to uniformly introduce the air-fuel mixture flowing in a certain direction into each intake passage; In the case of a horizontal carburetor, the fuel density tends to be higher in the lower part of the air-fuel mixture due to its nature, and there are variations in the air-fuel ratio of the air-fuel mixture itself in each intake passage, further compounding the above-mentioned disadvantages. .

The present invention attempts to improve the above-mentioned disadvantages in a multi-cylinder internal combustion engine equipped with a horizontal carburetor. Rather than simply branching into a three-pronged or four-pronged shape, the tip of each intake passage on the side where it connects to the collecting pipe section is such that the axis of each tip is approximately parallel to the axis of the collecting pipe section, and The tips are bundled so that they are arranged in a regular polygonal shape when viewed in the axial direction of the collecting pipe section, and the cross section of each tip end and the cross section of the collecting pipe section are aligned in the axial direction of the collecting pipe section. They are constructed so that they partially overlap each other when viewed, and by allowing the air-fuel mixture from the collecting pipe to travel straight to each intake passage, the air-fuel mixture from the carburetor can be distributed approximately equally to each intake passage. This is what I did.

Below, the drawings (Figs. 1 to 3) of an embodiment in which the present invention is applied to a three-cylinder internal combustion engine will be explained. In the drawings, A indicates the first cylinder A1, the second cylinder N, and the third cylinder. 1 is an intake manifold, 2 is a horizontal carburetor, and the intake manifold 1 has a generally horizontal collecting pipe portion 3 to which the horizontal carburetor 2 is attached at one end;
Each cylinder A19 A2 of the engine A. Intake port in A3) Three intake passages connected by flanges to 4, 5.6?
, 8.9 and each intake passage? , 8. In integrally connecting the tip of 9 to the other end of the collecting pipe section 3, 5
, each intake passage? , 8.9 is bent so that the axis of the tip is parallel or substantially parallel to the axis of the collecting pipe section 3, and each intake passage ? . So, each intake passage with respect to the cross section of the collecting pipe section 3? , 8.9 are connected so that each cross section partially overlaps with the other.

Further, each intake passage may be configured so that the length of each intake passage is equal.

Note that the reference numeral 11 in the figure is a part of a riser for preheating intake air.

With this configuration, the air-fuel mixture from the collecting pipe section 3 can be distributed to each intake passage. , Go straight towards the tip inlet of 8.9, and the mixture is in each intake passage? , 8.9 is distributed to each intake passage according to the area where it overlaps with the cross section of the collecting pipe section 3, so by appropriately setting this area where this overlap, the air-fuel mixture can be distributed equally to each intake passage. can be distributed.

That is, when a large amount of the air-fuel mixture from the collecting pipe section 3 tends to enter the intake passage 8 for the second cylinder, the overlapping area of the intake passage 8 for the second cylinder with the collecting pipe section 3 is If the overlapping area of the intake passage 7 and the intake passage 9 for the third cylinder into the collecting pipe section 3 is smaller than that of the intake passage 7 and the intake passage 9 for the third cylinder, and if there is a tendency for a large amount to enter the intake passages 7 and 9 for the first and second cylinders, By reducing the overlapping area of both intake passages 7.9, it is possible to equalize the distribution of the air-fuel mixture to each intake passage.

In this case, each intake passage? , 8.9 may be arranged in an inverted equilateral triangle arrangement as shown in FIG. 4, and in the case of a four-cylinder internal combustion engine A', each cylinder A□'v Ag't Intake passage for Ae'9N'? ', 8', 9'I O' should be aligned in a square or substantially square arrangement and connected in the manner described above to the collecting pipe section 3' to which the horizontal carburetor 2' is attached. The same application can be made to a hexagonal or substantially hexagonal arrangement.

As described above, according to the present invention, the air-fuel mixture from the horizontal carburetor can be distributed approximately equally to each cylinder in a multi-cylinder internal combustion engine, and the air-fuel ratio and charging efficiency can be averaged, so that combustion in each cylinder is uniform. While engine vibration and noise can be reduced, the air-fuel mixture flows straight from the collecting pipe to each intake passage, so there is little flow resistance from the carburetor to each cylinder, which has the effect of improving acceleration response and output. have

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a plan view when applied to a three-cylinder internal combustion engine, FIG. m-■ enlarged sectional view, 4th
The figure is a cross-sectional view of the same part as FIG. 3 in another embodiment, FIG. 5 is a plan view when applied to a four-cylinder internal combustion engine, and FIG. 6 is an enlarged cross-sectional view taken along the line - ■ of FIG. . A, A'... Engine, 2, 2'... Carburetor, 1゜1'... Intake manifold, 3.3
'...Collecting pipe section? , 8.9,? ', 8',
9', 10'...Intake passage.

Claims (1)

[Scope of utility model registration request] An intake manifold for distributing the air-fuel mixture from the horizontal carburetor to each cylinder of a multi-cylinder engine, a collecting pipe section attached to the horizontal carburetor, and each intake passage branching from the collecting pipe section and attached to each cylinder. In the intake system for an internal combustion engine, the manifold has a collecting pipe section disposed substantially horizontally, the tip end of each of the intake passages on the connection side with the collecting pipe section; The axes of the parts are substantially parallel to the axis of the collecting pipe part, and each of these tips is arranged in a regular polygon or a substantially regular polygon when viewed in the axial direction of the collecting pipe part. An air intake device for an internal combustion engine, characterized in that the tip portion is connected to the collecting pipe portion in a state in which each cross section of the tip portion partially overlaps a cross section of the collecting pipe portion.