JP2802308B2 - 4-cylinder engine intake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention can improve stable combustion and output by reducing intake interference between cylinders and obtaining a good air-fuel ratio distribution in a four-cylinder engine. The present invention relates to a four-cylinder engine intake device configured as described above.

[Conventional technology]

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

However, in the above-described shape of the intake passage, since the length lb of the intake passage from the second branch portion b to the cylinder inlet c of the cylinder is short, the volume efficiency is reduced due to the influence of the intake interference between the adjacent cylinders. However, there is a problem that the output is reduced.

Therefore, various proposals have been made so far in order to obtain a high output and improve the air-fuel ratio distribution in a multi-cylinder engine by reducing intake interference between the cylinders. For example, as shown in FIG. The length lb 'from the second branch b' to the intake port of the cylinder is longer than the length la 'from the first branch a' to the second branch b ', As shown in Japanese Unexamined Patent Publication No. 55-23458, the length from the second branch portion to the intake hole of the cylinder is increased,
2. Description of the Related Art There is known a prior art in which a ridge having a height of several millimeters is provided on an inner wall of a branch portion of a branch portion.

[Problems to be solved by the invention]

However, in each of the prior arts described above, the length of the intake passage is determined by the restrictions on the engine outfitting.
There is a problem that the branch portion and the second branch portion are too close to each other, so that the fuel distribution in the intake air-fuel mixture is not uniform, and the air-fuel ratio between the cylinders is not constant, so that the combustion deteriorates.

In particular, in a side-draft type carburetor, the fuel in the air-fuel mixture sucked through the carburetor flows through the intake passage due to inertial force, so that large-particle fuel flows in a concentrated manner in the center, which is inevitable. 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 central air intake passage becomes rich, causing unstable combustion.

Furthermore, since the intake passage is provided horizontally,
If the intake air amount is very small, such as at start-up or at extremely low load,
There is a problem that mixing with the outflowing fuel is poor, that is, when so-called droplet fuel flows through the inner wall of the intake passage, it tends to drift to a specific cylinder.

The present invention has been proposed in view of the above-described problems. Even in a side draft type carburetor of a four-cylinder engine for an automobile, it reduces intake interference between the cylinders, and provides a uniform air-fuel ratio for each cylinder. An object of the present invention is to provide an intake device for a four-cylinder engine capable of stabilizing combustion and improving output by obtaining distribution.

[Means for solving the problem]

In order to achieve this object, the present invention relates to an engine provided with a side draft type carburetor, which branches off from a linear collective intake passage connected to the carburetor outlet side and communicates with each cylinder. The branch side opening of the intake passage to be located is located substantially on the same line, and is branched from the collective intake passage #
The openings of the intake passages corresponding to the inner # 2 and # 3 cylinders are formed adjacent to the intake passages at both ends corresponding to the # 1 and # 4 cylinders, and the openings are located upstream of the openings of the adjacent intake passages. A column-shaped partition wall that does not impede the flow of intake air, and a groove is formed at the bottom of the above-mentioned collective intake passage along the center of the pipeline up to the vicinity of the opening of each intake passage branched from the upstream side. It is.

[Action]

With such a configuration, in the intake device for a four-cylinder engine of the present invention, the length of the intake passage to each cylinder inlet can be made relatively long, and the # 2 and # 2 cylinders inside the four-cylinder engine can be formed. Since the phase difference with the three cylinders is 360 degrees, the influence of the pressure wave due to the intake interference is small, and the output can be improved.

Furthermore, a columnar partition wall that does not hinder the flow of intake air is provided upstream of the opening of the adjacent intake passage, and each intake branch branched from the upstream is provided at the bottom of a horizontal collective intake passage located upstream of each intake passage. Since the groove is formed along the center of the pipe to the vicinity of the opening of the passage, the inertial force of the fuel in the mixture flowing through the carburetor is attenuated by the columnar partition walls, and the mixture is uniformly distributed to each intake passage. And stable combustion is maintained, and the output is improved.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a four-cylinder engine to which an embodiment of the present invention is applied, and FIG. 2 is a partially cutaway top view of an intake device. Indicates an intake manifold.

Here, the engine body 1 is arranged to be inclined by θ degrees (about 21.5 degrees) with respect to the horizontal line of the vehicle body, and the air-fuel mixture sucked through the side draft type carburetor 4 is supplied to the intake manifold 3. Thus, the pressure is equally distributed to each cylinder.

The intake manifold 3 is connected to a collective intake passage 5 connected to the outlet side of the carburetor 4 and branches to the # 1, # 2, # 3, and # 4 cylinders in the cylinder head 2 from the collective intake passage 5, respectively. The communicating intake passages 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ are integrally formed. And an intake passage 6 _1, 6 _2, 6 _3, 6 ₄ aperture center 7 _1, 7 _2, 7 _3, 7 ₄ branching from the collection intake passage 5, is positioned on substantially the same line, the aperture center Curved intake passages to # 1, # 2, # 3, and # 4 cylinders downstream of 7 ₁ , 7 ₂ , 7 ₃ , 7 ₄
The pipe length L of 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ is made relatively long, and the collective intake passage 5 upstream of the opening centers 7 ₁ , 7 ₂ , 7 ₃ , 7 ₄ is provided.
Are formed substantially linearly, and the assembled intake passage 5 is formed so as to be horizontal with respect to the vehicle body when assembled to the engine body 1. Also, the center 7 ₁ of the opening of the intake passages 6 ₁ and 6 ₄ corresponding to the # 1 and # 4 cylinders of the intake manifold 3,
For 7 ₄ , intake passage corresponding to inner # 2 and # 3 cylinders
Opening centers 7 ₂ and 7 ₃ of 6 ₂ and 6 ₃ adjacent to each other,
The aforementioned intake passage 6 _2, 6 ₃ of the aperture center 7 _2, 7 ₃ from the upstream side of the set intake passage 5, the columnar partition wall 8 is provided with a sufficient distance so as not to interfere with the flow of intake .

The columnar partition wall 8 has a surface 8a perpendicular to the flow toward the upstream side.
Has, together with the attenuating the inertial force mixture flowing through the set intake passage 5 from the vaporizer 4 is to flow directly into the intake passage 6 _2, 6 _3, by changing the direction of flow, the intake passage 6 ₁ , 6 ₂ ,
6 _3, 6 is adapted to substantially uniformly adjusted the distribution of the mixture flowing to _4.

Further, in the intake manifold 3, a bifurcated branch is formed at a bottom of the linearly formed collective intake passage 5 at a branch portion 9 from the upstream side of the collective intake passage 5, and further, on both sides of the columnar partition wall 8. The two branches branch off in the vicinity of the downstream branch points 10a and 10b in the vicinity, and the grooves 11 ₁ and 11 ₂ are formed along the center of the pipeline to the vicinity of the openings of the respective intake passages 6 ₁ , 6 ₂ , 6 ₃ and 6 _4. , so as to equalize to 11 _3, 11 ₄ has been formed, the liquid film-like flow each intake passage ₆₁ of the fuel, 6 _2, 6 _3, 6 _4.

In other words, the intake passage, the period from the set intake passage 5 until slightly downstream of the opening to the intake passage ₆₁ through _4, because it is mounted to the intake manifold 3 substantially horizontally, above the portion grooves 11 ₁ to 11 ₄ are formed.

In the embodiment configured as described above, the length L ₁ of the intake passages 6 ₁ , 6 ₂ , 6 ₃ , 6 _{4 to} each cylinder inlet can be formed relatively long, and moreover, in general, four cylinders The ignition order of the engine is # 1 → # 3 → # 4 → # 2 cylinder or # 1 →
# 2 → # 4 → # has a 3, since the phase difference between any case in the # 2 cylinder # 3 cylinder is 360 degrees, the intake passage 6 ₂ corresponding to the # 3 cylinder and # 2 cylinder, 6 ₃ opening center 7 ₂ , 7 ₃
Are adjacent to each other, the influence of the pressure wave due to the intake interference does not occur.

In addition, the inertia of the air-fuel mixture flowing from the vaporizer 4 is
Therefore, there is no drift to each of the intake passages 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ , and the mixture is evenly distributed.

〔The invention's effect〕

As described above, the intake device for a four-cylinder engine according to the present invention is arranged such that the branch-side opening of the intake passage communicating with each cylinder branched from the linear collective intake passage connected to the carburetor outlet side is substantially collinear. , A substantial pipe length from the opening of each intake passage branched from the collective intake passage to each cylinder inlet can be lengthened, so that the influence of intake interference is reduced and the output can be improved.

Further, the openings of the intake passages corresponding to the inner # 2 and # 3 cylinders are formed adjacent to the both end intake passages corresponding to the # 1 and # 4 cylinders branched from the collective intake passage, and are adjacent to each other. Since a columnar partition that does not hinder the flow of intake air is provided upstream of the opening of the intake passage, the inertial force of the fuel in the air-fuel mixture flowing through the carburetor is attenuated by the columnar partition. Since the air-fuel mixture distribution is equalized and stable combustion is maintained, the output is improved.

Furthermore, the phase difference between the inner # 2 cylinder and the # 3 cylinder is
Since the angle is 360 degrees, the influence of the pressure wave due to the intake interference is small, and the output can be improved.

Also, since a groove is formed along the center of the pipeline at the bottom of the collective intake passage to the vicinity of the opening of each intake passage branched from the upstream side, the liquid film fuel uniformly flows into each intake passage, The air-fuel ratio of the air-fuel mixture between the cylinders is made uniform.

[Brief description of the drawings]

FIG. 1 is a side view of a four-cylinder engine to which an embodiment of the present invention is applied, FIG.
FIG. 4 and FIG. 4 are explanatory views showing a conventional intake passage. 1 ... engine body, 3 ... intake manifold, 4 ...
Vaporizer, 5 ... Collective intake passage, 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ ... Intake passage, 7 ₁ , 7 ₂ , 7 ₃ , 7 ₄ ... Center of opening, 8 ... Column-shaped partition wall, 1
1 ₁ , 11 ₂ , 11 ₃ , 11 ₄ ... groove.

Claims (1)

(57) [Claims] 1. An engine provided with a side draft type carburetor, wherein a branch side opening of an intake passage branched from a linear collective intake passage connected to the carburetor outlet side and communicating with each cylinder. Parts are located substantially on the same line, and the openings of the intake passages corresponding to the inner # 2 and # 3 cylinders are arranged at the both end side intake passages corresponding to the # 1 and # 4 cylinders branched from the collective intake passage. A columnar partition formed adjacently and not obstructing the flow of intake air upstream of the opening of the adjacent intake passage is provided. At the bottom of the collective intake passage, near the opening of each intake passage branched from the upstream. An intake device for a four-cylinder engine, wherein a groove is formed along the center of the pipeline.