JPH02291470A - Suction system of four-cylinder engine - Google Patents

Abstract

PURPOSE:To damp the inertia force of the fuel running in a central side suction path, and to distribute and supply mixed air equally to each suction path by forming a columnar partition on the branch points of each suction paths on both sides as well as on the central side communicating with each air cylinder. CONSTITUTION:In a suction system of a four-cylinder engine that distributes mixed air from a carburetor 10 to each air cylinder #1-#4, suction paths 1, 4 on both sides communicating with the first and the fourth air cylinders, #1, #4, respectively, and a suction path 5 on the central side communicating with the second and the third air cylinders #2, #3, are branched into three directions at a first branch point 6 on the side of the carburetor 10. In this structure, the suction path 5 on the central side of the first branch point 6 is branched into two directions to the sides of the second and the third air cylinders #2, #3 at a second branch point 7 on the lower side. On the branch point of the first branch point 6, a columnar partition 8 is formed, while the second branch point 7 is arranged in the vicinity of the columnar partition 8. The inertia force of the fuel running in the central side suction path 5 is damped.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves stable combustion and output by reducing intake air interference between each cylinder and obtaining a good air-fuel ratio distribution in a four-cylinder engine. The invention relates to a four-cylinder engine intake system.

[Conventional technology]

Generally, in a four-cylinder engine, an intake passage branching from a carburetor to each cylinder is formed as shown in FIG.

However, in the shape of the intake passage described above, the second branch b
Since the length 1b of the intake passage from the cylinder to the cylinder inlet C of the cylinder is short, there is a problem that the volumetric efficiency decreases due to the influence of intake air interference between adjacent cylinders, resulting in a decrease in output.

Therefore, various proposals have been made so far in order to reduce intake air interference between each cylinder in a multi-cylinder engine, obtain high output, and improve air-fuel ratio distribution.
As shown in the figure, the length 'b from the second branch part b' to the intake hole of the cylinder is longer than the length ILa from the first branch part a' to the second branch part b' on the carburetor side. Or, as shown in Utility Model Application Publication No. 55-23458, the second
Prior art is known in which the length from the branch part to the intake hole of the cylinder is increased, and a protrusion several millimeters in height is provided on the inner wall of the branch part of the first branch part.

[Problem to be solved by the invention]

However, in all of the above-mentioned prior art, since the length of the intake passage is determined by constraints on engine maintenance, the first branch part and the second branch part are too close to each other, resulting in uneven fuel distribution in the intake air-fuel mixture. Moreover, since the air-fuel ratio between each cylinder is not constant, there are problems such as deterioration of combustion.

Particularly with side-draft type carburetors, the fuel in the air-fuel mixture sucked through the carburetor flows through the intake passage due to inertia, so the fuel with large particles flows concentrated in the center, so it is inevitable that The air-fuel ratio of the air-fuel mixture flowing through the intake passages at both ends becomes lean, and the air-fuel ratio of the air-fuel mixture flowing through the center intake passage becomes rich, causing instability in combustion.

The present invention was proposed to address the above-mentioned problems, and even in a side-draft type carburetor for a four-cylinder automobile engine, it reduces intake interference between each cylinder and provides uniform airflow to each cylinder. It is an object of the present invention to provide an intake system for a four-cylinder engine that can stabilize combustion and improve output by obtaining fuel ratio distribution.

[Means to solve the problem]

In order to achieve this object, the present invention has an intake manifold on both ends that communicates with cylinders #1 and #4 of a four-cylinder engine that distributes air-fuel mixture from a carburetor to each cylinder, and an intake manifold that communicates with cylinders #2 and #3. In the intake device in which the central side intake passage is branched into three directions at the first branch part on the carburetor side, the first
The intake passage on the center side of the branch is #2 at the second branch on the downstream side.
It is characterized in that it branches into two forks toward the #3 cylinder side, a columnar partition is formed at the branching point of the first branch, and the second branch is located close to the columnar partition. .

[For production]

In such a configuration, in the intake system for a four-cylinder engine of the present invention, the intake passages at both ends communicating with the #1 and #4 cylinders and the center intake passage communicating with the #2 and #3 cylinders are connected to the carburetor. It branches into three directions at the first branch on the side, and the central intake passage of the first branch branches into two forks toward the #2 and 63 cylinders at the second branch on the downstream side. Since a columnar partition is formed at the branch point to improve fuel distribution, and the second branch is located close to the columnar partition, the inertial force of the fuel in the air-fuel mixture flowing through the carburetor and into the central intake passage is reduced. The fuel is attenuated by the columnar partitions, and the flow direction is changed so that the fuel is evenly distributed to both end-side intake passages and the center-side intake passage.

Therefore, the fuel does not drift toward a specific cylinder depending on the ignition order due to the inertial force of the fuel, a uniform air-fuel ratio is obtained, and stable combustion is maintained, resulting in stable output.

Furthermore, since the length from the first branch to the inlet of each cylinder is longer, the influence of intake air interference is reduced and high output can be obtained.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view showing an intake system for a four-cylinder engine according to an embodiment of the present invention.
3.4 are #1. This is an intake passage corresponding to cylinders #2, #3, and #4.

The intake passages 1.4 at both ends corresponding to the #1 and #4 cylinders and the intake passage 5 at the center branch into three directions at a first branch 6 on the carburetor side. The branched central intake passage 5 branches into two forks at a second branch 7 on the downstream side to form intake passages 2.3 corresponding to the #2 and #3 cylinders.

Further, at the branching point of the first branching section 6, the inertial force of the fuel in the mixture flowing from the carburetor 10 toward the central intake passage 5 is attenuated, and the direction of the flow is changed to A columnar partition wall 8 is formed to distribute the air-fuel mixture toward both end-side intake passages 1.4 and the center-side intake passage 5 side. It has become. The second branch portion 7 is formed at a position adjacent to the downstream side of the columnar partition wall 8 .

Here, the ignition order of the above four-cylinder engine is #1 → #3 →
#4 → #2 cylinder, and the air-fuel mixture flowing through the carburetor 10 is sucked in the order of intake passage 1-5 → 4 → 5 → 1.

Therefore, the fuel does not drift toward a specific cylinder depending on the ignition order due to the inertial force of the fuel, and the air-fuel ratio becomes uniform.

In addition, with respect to the length L1 of the intake passage 1.4 on both end sides from the first branch part 6 to the cylinder inlet of the #2, #4 cylinder, the intake passage from the second branch part 7 to the cylinder inlet of the #2, #63 cylinder. Passage 2
．． The length 11 of 3 can be formed to be relatively long, and the phase difference between the #2 cylinder and the #3 cylinder is 360', so that the length 11 corresponds to the intake passages 2 and 3 branched from the second branch part 7. No influence of pressure waves due to intake air interference occurs between cylinder #2 and cylinder #3.

Therefore, according to the intake system for a four-cylinder engine of the present invention,
The intake passage from the second branch part 7 to the #2 and #3 cylinder inlets is the length 11 of the intake passages 2 and 3 plus the length up to the first branch part 6, and is essentially J , # are made longer, so the influence of pressure waves due to intake air interference between each cylinder is small.

Furthermore, since the inertial force of the air-fuel mixture is attenuated by the columnar partition wall 8, the air-fuel mixture is evenly distributed to each intake passage L, 2, 3.4.

FIG. 2 is a schematic explanatory diagram of another embodiment of the intake system for a four-cylinder engine according to the present invention, and since it is similar to the embodiment described above, the explanation will be omitted.

Moreover, FIGS. 3(a) to 3(f') are sectional views showing other shapes of the columnar partition walls according to the present invention, which can be set as appropriate.

〔Effect of the invention〕

As explained above, the intake system for a four-cylinder engine according to the present invention connects both end side intake passages communicating with the #1 and #4 cylinders and the central side intake passage communicating with the #2 and #3 cylinders to the carburetor. It branches into three directions at the first branch on the side, and the central intake passage of the first branch branches into two forks toward the #2 and #3 cylinders at the second branch on the downstream side. Since a columnar partition is formed at the branch point of the fuel mixture to improve distribution, and the second branch is located close to the columnar partition, the fuel in the air-fuel mixture flowing through the carburetor and into the central intake passage. Since the inertial force of the engine is attenuated by the columnar partitions, the air-fuel mixture is evenly distributed to each intake passage, maintaining stable combustion and improving output.

Furthermore, since the substantial length of the intake passage from the second branch to the inlet of each cylinder becomes longer, the influence of intake air interference is reduced and output can be improved.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a sectional view showing an intake system of a four-cylinder engine which is an embodiment of the present invention, Fig. 2 is a schematic explanatory diagram of another embodiment of the same, and Fig. 3 is a sectional view of the intake system of a four-cylinder engine according to the present invention. FIGS. 4 and 5 are sectional views showing other shapes of columnar partitions, and are explanatory views showing conventional intake passages. 1, 4... Both end side intake passages, 2, 3... Intake passages,
5... Central side intake passage, 6... First branch part, 7...
- Second branch, 8... columnar partition. N4G patent applicant Fuji Heavy Industries Co., Ltd. agent Patent attorney Jundo Kobashi Patent attorney Susumu Murai

Claims (1)

[Scope of Claims] Both end side intake manifolds communicate with #1 and #4 cylinders of a four-cylinder engine that distributes air-fuel mixture from a carburetor to each cylinder, and a center side intake passage that communicates with #2 and #3 cylinders. In the intake system which branches into three directions at the first branch part on the carburetor side, the central intake passage of the first branch part is connected to the #2 and #3 cylinder sides at the second branch part on the downstream side. An intake system for a four-cylinder engine, characterized in that it is bifurcated, a columnar partition is formed at the branch point of the first branch, and the second branch is located close to the columnar partition.