JPS6134343A - Intake manifold for three-cylinder engine - Google Patents

Abstract

PURPOSE:To stabilize the performance of an engine, by making the lengths of intake passages from a carburetor to cylinders equal to each other. CONSTITUTION:An intake manifold 9 comprises a single main confluence pipe 10 connected to a carburetor 7, and a first, a second and a third branch pipes 11-13 connected to intake ports 1-3. The main confluence pipe 10 is placed above the branch pipes 11-13. The main confluence pipe 10 is connected to the branch pipes 11-13 through a first and a second auxiliary confluence pipes 21, 22 and a communication pipe 23 in such a manner that the main confluence pipe extends at an upper level and the branch pipes extend at a lower level.

Description

[Detailed description of the invention] (Industrial application field) The present invention is applied to an intake manifold of a three-cylinder engine.

(Prior art and its problems) The conventional intake manifold of a three-cylinder engine has a structure in which air is taken from the carburetor 7 to the first and third cylinders 4.6 to the total and the second cylinder 5, as shown in Fig. 5. The aisle lengths are different. That is, the length of the intake passage up to the second air n5 is shortened. Therefore, the distribution speed of the air-fuel mixture to each cylinder 4, 5, 6 is different, resulting in a problem that the engine performance becomes unstable.

In addition, since the entire intake manifold is formed in a generally flat shape, if an attempt was made to ensure a sufficient passage length, the intake manifold and carburetor 7 would protrude significantly in the six directions of the arrows in Fig. 5, making the engine dimensions too large. There is also a problem that this happens.

In addition, as a prior document, there is Utility Model Application Publication No. 58-172013.

(Object of the Invention) The first invention of the present application attempts to stabilize engine performance by making the length of the intake passage from the carburetor to each cylinder equal.

Further, the second invention aims to stabilize the engine performance and make the engine more compact.

(Means for Achieving the Object) In order to achieve the above object, the first invention of the present application provides one collection source pipe connected to the main 11 blator, and a first, second, third
comprising first, second, and third branch pipes connected to the cylinders, respectively;
The first and third branch pipes are connected to both ends of the connecting pipe, and the second
Connect the branch pipe to the center of the connecting pipe, and connect the collecting pipe to the first and second pipes.
Branching into sub-collecting pipes, placing the first sub-collecting pipe at the center of the connecting pipe between the first and second branch pipes, and placing the second sub-collecting pipe at the center of the communicating pipe between the second and third branch pipes. They are connected to each other so that the length of the intake passage from the carburetor to each cylinder is equal.

In addition to the configuration of the first invention, the second invention further provides a configuration in which the source pipe is arranged above each branch pipe, and each sub-collection pipe is arranged approximately at right angles to the branch pipe, so that the entire intake manifold is divided into two parts. It is stacked in tiers.

(Example) - Fig. 1 is a schematic perspective view of an intake manifold for a three-cylinder engine that has both the first and second aspects of the invention. , a third intake port formed on the side surface of the cylinder head 8, and a third intake port formed on the side surface of the cylinder head 8;
, 2nd and 3rd air m4.5.6 respectively.

The intake manifold 9 includes one main pipe 10 connected to the carburetor 7, and first, second, and third branch pipes 11.12.13 connected to each intake port 1.2.3, respectively. . The main collecting pipe 10 is arranged above the branch pipes 11.12.13, and the main collecting pipe 10 and the branch pipes 11.12.13 are connected to two first and second sub-collecting pipes 21.22 and a connecting pipe. 23, they are connected in a two-tier stacked manner.

That is, the communication pipe 23 is arranged horizontally at right angles to the branch pipes 11, 12, 13, and the inlets of the first branch pipe 11 and the third branch pipe 13 are connected to both ends of the communication pipe 23, respectively. A second branch pipe 12 is installed in the center of the communication pipe 23 (a part equidistant from both ends).
The inlet part of is connected. First and second sub-collecting pipes 21.2
2 branches horizontally from the main collecting pipe 10 to the left and right, and each bends downward in the middle, and the first sub collecting pipe 2
1 is connected to the center of the communication pipe 23 between the first and second branch pipes 11.12, and - the second sub-collecting pipe 22 is connected to the second and third branch pipes 12.
It is connected to the center of the communication pipe 23 between the pipes 13 and 13. The first and second sub-collecting pipes 21.22 are the first, second and third branch pipes 11.1.
2.13. Therefore, this intake manifold 9 is connected to the second branch pipe 12.
It is formed in a shape that is symmetrical with respect to the vertical plane passing through the collecting source pipe 10, and from the carburetor 7 to each intake port 1.
．． The respective intake passage lengths up to 2.3 are equal to each other. The structure is a so-called modified tournament format.

2nd, 3rd, gate 4 diagrams, and 1st diagram. Intake, Yu, -1°do9
In FIG. 2 showing a plan view, a main collecting pipe 10, branch pipes 11, 12, 13, and a sub collecting pipe 21 are shown.
．． 22 and the communication pipe 23 are formed as one piece,
Further, the collecting source pipe 10 and each branch pipe 11, 12, 13 are formed short in the length direction (direction of arrow A7) thereof.

3 and 4, the outlet end of each branch pipe 11, 12, 13 is formed with a mounting 7 flange 30, 31, 32. 2 to 4, the inner diameter of the connecting pipe 23 is shown as a generally uniform diameter, but since the air-fuel mixture flows into the second branch pipe 1'2 from both the left and right sides, the suction of the second branch pipe 12 is Quantity first,
In order to align with the suction of the third branch pipe 11.13, the inner diameter of the portion of the connecting pipe 23 between the collecting pipes 21, 22 on both sides (width portion in Fig. 1) is set to be smaller than the inner diameter of both ends of the connecting pipe 23. I'm keeping it small.

(Function) The air-fuel mixture supplied from the carburetor 7 to the main collecting pipe 10 is first equally and simultaneously distributed to the collecting pipes 21 and 22 on both sides. The air-fuel mixture is supplied from the first sub-collecting pipe 21 to the central portion of the communication pipe 23 between the first branch pipe 11 and the second branch pipe 12. The air-fuel mixture is supplied from the second sub-collecting pipe 22 to the central portion of the communication pipe 23 between the third branch 13 and the second branch pipe 12. Then, it is simultaneously distributed from the communication pipe 23 to each branch pipe 11, 12, 13, and supplied to each cylinder 4, 5, 6. That is, since the lengths of the intake passages from the carburetor 7 to each intake port 1.2.3 are equal, the distribution speed of the mixture to each cylinder 4.5.6 becomes equal, resulting in simultaneous distribution. .5
．． 6's power performance is stable.

In addition, in a 3-cylinder engine, the first cylinder generally has 4 cylinders and the third cylinder has 6 cylinders.
and the second cylinder 5 are set to burn in this order,
When the air-fuel mixture that is being introduced into the first cylinder 4 is suddenly changed to the third cylinder 6, which is the next combustion order, the air-fuel mixture does not return to the carburetor = 7 as in the conventional case, but the connecting pipe 23 is The air is directly supplied to the third branch pipe 13 and the third intake port 3 through the air, and the distribution speed is faster than that of the conventional system.

To explain in more detail, during the intake stroke of the first cylinder 4,
The air-fuel mixture that flows from the source pipe 10 to the first branch pipe 11 via the first sub-manifest pipe 21' becomes the mainstream, but
There is also a side stream flowing to the first branch pipe 11 via the connecting pipe 23. - During the intake stroke of the three power cylinders 6, the air-fuel mixture that flows from the source pipe 10 to the third branch pipe 13 via the second sub-collection pipe 22 becomes the mainstream, and from the first sub-collection pipe 21 to the connecting pipe 23. The air-fuel mixture that flows into the third branch pipe 13 via the substream becomes a side stream. Therefore, when the intake stroke changes from the first cylinder 4 to the third cylinder 6, from the main collecting pipe 10 to the second! 1ill Evacuation to collecting pipe 22 @e (1), Wow, 11 cases. good. . . 6(7)
', there is little resistance when the third cylinder 6 starts up, and the air-fuel mixture starts to be smoothly supplied to the third branch pipe 13 and the third cylinder 6. Further, due to the intake closing operation of the first cylinder 4, the pressure increase in the first sub-collecting pipe 21, the communication pipe 23, and the first branch pipe 11 is guided to the third branch pipe 13, and the pressure of the air-fuel mixture is increased.

(Effects of the Invention) (1) In the first and second inventions, by providing the first and second sub-collecting pipes branching from the main collecting pipe, the length of the intake passage from the carburetor to each intake port is made equal. Since the intake manifold is configured as follows, the air-fuel mixture is distributed at the same speed to each cylinder, allowing simultaneous distribution.
This stabilizes the power performance of each cylinder and the overall engine performance.

(2) The first, second, and third branch pipes are communicated with each other by a communication pipe, the first sub-collection pipe is communicated with the central part of the communication pipe between the first and second branch pipes, and the second sub-collection pipe is connected to the middle part of the communication pipe between the first and second branch pipes. Since the central part of the pipe between the second and third branch pipes communicates with each other, for example, when changing from the intake stroke of the first cylinder to the intake stroke of the third cylinder, the first and second branch pipes communicate with each other.
The air-fuel mixture in the collecting pipe and the communication pipe does not return to the carburetor side, but is directly supplied to the third branch pipe via the communication pipe. Therefore, compared to the conventional example shown in FIG. 5, the distribution speed becomes faster and the performance of the engine is improved.

(3) In the second invention, the source pipe is arranged above the branch pipe, and each sub-collection pipe is arranged at approximately right angles to the branch pipe, so that the entire intake manifold is of a two-tiered type. , even if the intake passage length is made as long as before,
The amount of protrusion of the manifold and carburetor from the engine can be shortened, thereby reducing the size of the engine.

In addition, by shortening the distance from the side of the cylinder head to the carburetor, the vibration (oscillation) of the chitopreter can be reduced.
As a result, the oil level in the float chamber of the carburetor becomes stable, and engine performance becomes stable.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of an intake manifold to which the first and second inventions of the present application are applied, FIG. 2 is a plan view showing an embodiment of FIG. 1, and FIG. , Figure 4 shows r in Figure 3.
The V-rV sectional view and FIG. 5 are plan views of the conventional example. 4.
5.6...Cylinder, 7...Carburetor, 10...
Collection source pipe, 11.12.13... Branch pipe, 21.22.
...Sub-collecting pipe, 23...Connecting pipe ・Figure 1 Figure 2 Figure 3 W Figure 4 Figure 5

Claims (2)

[Claims] (1) One collecting pipe connected to the carburetor and the first
, the first, second, and third cylinders connected to the second and third cylinders, respectively.
A branch pipe is provided, the first and third branch pipes are connected to both ends of the communication pipe, the second branch pipe is connected to the center of the communication pipe, and the source pipe is branched into the first and second sub-collection pipes. and connect the first sub-collecting pipe to the first,
In the center of the communication pipe between the second branch pipes, connect the second sub-collecting pipe to the second branch pipe.
An intake manifold for a three-cylinder engine, characterized in that the intake manifold is connected to the central part of the communication pipe between the third branch pipes so that the length of the intake passage from the carburetor to each cylinder is equal. (2) One collecting pipe connected to the carburetor and the first
, the first, second, and third cylinders connected to the second and third cylinders, respectively.
A branch pipe is provided, the first and third branch pipes are connected to both ends of the communication pipe, the second branch pipe is connected to the center of the communication pipe, and the source pipe is branched into the first and second sub-collection pipes. and connect the first sub-collecting pipe to the first,
In the center of the communication pipe between the second branch pipes, connect the second sub-collecting pipe to the second branch pipe.
The connecting pipes between the third branch pipes are connected to each other in the center, the collecting source pipe is placed above each branch pipe, and each sub collecting pipe is arranged approximately at right angles to the branch pipes, so that the entire manifold is divided into two parts. The intake manifold for a three-cylinder engine is characterized by its stacked structure.