JP3138130B2 - Intake manifold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake manifold forming an intake system of an engine.

[0002]

2. Description of the Related Art Conventionally, as an intake manifold of this type, for example, in the case of a three-cylinder engine, an intake passage is divided into two near an inlet on the carburetor side, and one of the intake passages is divided into two parts further downstream, and each cylinder is divided into cylinders. A so-called tournament type connected to a game is well known. In such an intake manifold, there is a difference in the performance of fuel distribution in each intake passage, especially in a low-rotation, high-load operation state in which the throttle valve is fully opened, and furthermore, a liquid fuel without being atomized is used. May flow in.

[0003]

Problems to be Solved by the Invention On the other hand, Japanese Utility Model Laid-Open No. 555-2
No. 3458 describes an intake manifold having a configuration in which a ridge is provided on a lower half portion of an inner wall at a branch portion branched from a carburetor to a cylinder. The ridge has a length equal to the width of the branch portion, and the liquid fuel flowing out of the carburetor flows along the surface of the ridge by an intake air flow at the time of intake, and is generated when leaving the ridge. And act to promote atomization.

[0004] However, if such a ridge is provided so as to fill the entire width of the branching portion and to have a height sufficient to block the liquid fuel flowing out of the carburetor, suction resistance occurs during intake, As a result, the engine output is reduced. Therefore, when such a ridge is applied to a tournament type, atomization may be promoted, but if the suction resistance increases, the fuel distribution performance will further differ, and the combustion performance may decrease. There is.

[0005] An object of the present invention is to solve such a problem.

[0006]

In order to achieve the above object, the present invention takes the following measures. That is, the intake manifold according to the present invention,
The intake passage is divided at least in the vicinity of the inlet connected to the carburetor, and at least one of the two is further divided into two, and the intake passage communicates with the outlets respectively connected to the intake holes of the plurality of cylinders . The number of exits in one is bisected by the other
A projection is provided which is larger than the number of outlets and is provided in the vicinity of the inlet and at an intermediate portion between the bottom surface portion of the intake passage and one side surface portion which is bisected in a direction to reduce the longitudinal sectional area of the intake passage. The intake passage of the part where the projection is provided is almost water
It is characterized by being held in a horizontal direction .

[0007]

With such a construction, when the liquid fuel flows from the carburetor through the inlet, it flows through an intermediate portion between the bottom surface portion of the intake passage and one of the two side surfaces, and collides with the projection. The colliding liquid fuel is atomized into the intake passage by the collision, and is changed so as to also flow into the other half of which the inflow direction is divided. In other words, the protrusion changes the direction of the liquid fuel that easily flows into one of the two halves, and promotes atomization of the fuel. Therefore, even in a low-rotation, high-load operating state, there is no variation in fuel distribution, and output performance is improved. In addition, the protrusion is sufficient to be small with respect to the cross-sectional area of the intake passage, and does not cause suction resistance.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

An intake manifold 1 shown in FIG. 1 is applied to a so-called slant engine EG in which a cylinder head 2 is inclined with respect to an engine mounting plane. In this embodiment, a so-called tournament for three cylinders is used. This is called an expression. Generally, in a tournament-type intake manifold, one of the divided intake passages is further divided into two, and the other is further divided into two.
In this embodiment, a branching method for three cylinders is shown. In addition, slant engine EG
As shown in FIG. 2, the vehicle is mounted with the cylinder head 2 inclined obliquely upward, and the carburetor CA is mounted substantially horizontally above the crankshaft of the slant engine EG. Then, an intake manifold 1 is mounted between the carburetor CA and the cylinder head 2 of the slant engine EG.

The intake manifold 1 is a carburetor C
A is divided into an intake passage 1b communicating with an inlet 1a connected to A, and one of the two is connected to a first outlet 1d connected to a first cylinder having an intake hole (not shown) of the cylinder head 2 via a first intake passage 1c. The other is further divided into two and divided into a second intake passage 1e and a third intake passage 1f.
The second intake passage 1e communicates with a second outlet 1g connected to the second cylinder, and the third intake passage 1f communicates with a third outlet 1h connected to the third cylinder. The first, second, and third intake passages 1c, 1e, and 1f are provided at respective outlets 1.
d, 1g, and 1h are curved near the inlet 1a of each of the intake passages 1c, 1e, and 1f, and the respective outlets 1d, 1g, and 1h face downward when the portions near the inlet 1a are held substantially horizontally. Have been. The position, angle, and the like of the branch from the intake passage 1b to the first, second, and third intake passages 1c, 1e, and 1f may be set according to the engine to be attached. Good.

The inlet 1a and the intake passage 1b are circular in cross section so that the mixture or the liquid fuel does not stay inside. At the inlet 1a, a projection 4 is provided so as to protrude so as to reduce the opening area. That is, in this embodiment, the projections 4 are flush with the connection surface 1p of the intake manifold 1 provided with the inlet 1a and protrude into the inlet 1a, and slightly protrude into the intake passage 1b. In addition, the protrusion 4 is located at the entrance 1.
a and the intermediate portion between the bottom surface portion 1i of the intake passage 1b and the side surface portions 1j on the second and third intake passages 1e and 1f, and the shape viewed from the inlet 1a side is the opening area of the inlet 1a. Has a substantially unequal leg trapezoidal shape, which is very small compared to Specifically, the side E1 on the bottom portion 1i side of the unequal leg trapezoidal shape expands toward the bottom portion 1i side, and the side E2 on the side portion 1j is substantially perpendicular to the inner surface of the intake passage 1b. It is,
It does not expand toward the upper part of the side part 1j. in addition,
The position of the projection 4 is set to a position through which the liquid fuel flowing out of the carburetor CA passes when mounted on the slant engine EG. On the other hand, the protrusion 4 is
The protrusion 4 does not need to be greatly extended to the side, and the protrusion 4 may have such a size that a predetermined rigidity can be exhibited without obstructing the liquid fuel. Is undesirably large.

The slant engine EG in this embodiment
The actual flow of the liquid fuel when the engine is operated at a low speed and a high load will be described. First, the liquid fuel flowing out of the carburetor CA flows out in a substantially horizontal direction and reaches the inlet 1a of the intake manifold 1. In this case, the portion near the inlet 1a of the intake manifold 1 is held substantially horizontally, and the liquid fuel flows into the bottom portion 1i of the inlet 1a. By the way, in the intake stroke, the intake air flows while rotating clockwise when viewing the inlet 1a from the carburetor CA side.
The liquid fuel that is about to flow through the intake passage 1b moves slightly upward from the bottom surface portion 1i along the inner surface of the intake passage 1b. Therefore, when the protrusion 4 is at the above-described position, the liquid fuel will surely collide before diffusing into the intake passage 1b. As described above, since the projection 4 has the expanding side E1 on the bottom surface portion 1i side, the liquid fuel flowing through the bottom surface portion 1i collides more reliably. As shown schematically in FIG. 5, a part of the liquid fuel that has collided with the projection 4 changes its inflow path toward the first intake passage 1c, and a part of the fuel that has collided and reflected is It is discharged into the space inside the intake passage 1b and atomized.

As a result, the amount of fuel flowing into the first intake passage 1c is suppressed from being smaller than the amount of fuel flowing into the second and third intake passages 1e and 1f, and the air-fuel ratio in each cylinder is equalized. That is, as shown in FIG. 6, in the conventional operation (indicated by the mark x and the white triangle), the air-fuel ratio A / F of the first cylinder is increased in the operating state where the rotation speed becomes 1500 to 2500 rpm when the throttle valve is fully opened. While it is considerably leaner than the other cylinders (maximum difference 2.2), in this embodiment (indicated by white circles), it is averaged and the air-fuel ratio A / F difference ( The maximum difference 0.8) is small. Therefore, since the variation in the air-fuel ratio A / F of each cylinder is eliminated, the combustion efficiency is improved,
Output performance under high load operating conditions is improved. Also,
The protrusion 4 is formed with a minimum cross-sectional area with respect to the intake passage 1b and extends from the inlet 1a with a minimum length in the intake passage 1b, so that the suction resistance does not increase. Furthermore, in this embodiment, since the projections 4 are provided at the inlet 1a, the liquid fuel flowing out of the carburetor CA can reliably collide with the projections 4 before diffusing into the intake passage 1b. It is possible to surely promote the fuel supply and further improve the fuel distribution performance.

The present invention is not limited to the embodiment described above, and the number of cylinders of the engine to which the present invention is applied may be other than the three cylinders of the above embodiment. Also, for example, the protrusion 4 may not be formed flush with the connection surface 1p,
It may be formed on the inlet 1a side of the intake passage 1b. In this case, the surface of the projection 4 facing the entrance 1a is a flat surface, and the shape can be an unequal leg trapezoidal shape similar to the above embodiment. The formation position in the height direction is
In accordance with the rotation of the intake air flow, the liquid fuel may be set to a position where the liquid fuel passes before the liquid fuel enters the diffusion state.

In addition, the configuration of each part is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0016]

As described above in detail, according to the present invention, even when the fuel flows in a liquid state from the carburetor in a low-rotation, high-load operation state, the liquid fuel collides with the projection without fail. As the inflow course is changed, fuel can be evenly distributed to each cylinder without biasing to a specific one of the branched intake passages, and atomization is promoted by collision, improving combustion efficiency Can be done. further,
By improving the combustion efficiency, it is possible to improve the output performance in the above operating state.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention.

FIG. 2 is a side view showing a slant engine to which the embodiment is applied.

FIG. 3 is an end view of an entrance of the embodiment.

FIG. 4 is a plan view of the embodiment.

FIG. 5 is a schematic diagram for explaining the operation of the embodiment.

FIG. 6 is a graph showing the distribution of the air-fuel ratio between the embodiment and the conventional example.

[Explanation of symbols]

 2 ... Cylinder head 1 ... Intake manifold 1a ... Inlet 1b ... Intake passage 1c ... First intake passage 1d ... First exit 1g ... Second exit 1h ... Third exit 1i ... Bottom part 1j ... Side part 4 ... Protrusion CA ... Carburetor

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-332213 (JP, A) JP-A-63-306268 (JP, A) JP-A-1-63766 (JP, U) JP-A-2-332 64746 (JP, U) 2-144653 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 35/10

Claims (1)

(57) [Claims] In an intake manifold, an intake passage is divided at least in the vicinity of an inlet connected to a carburetor, and at least one of the two is further divided into two to communicate with outlets respectively connected to intake holes of a plurality of cylinders. The number of one of the two outlets is
The number of other outlets in the vicinity, and near the inlet,
In addition , a projection protruding in a direction to reduce the vertical cross-sectional area of the intake passage is provided at an intermediate portion between the bottom surface portion of the intake passage and the one side surface portion that is divided into two, and the intake air having the projection is provided .
An intake manifold, wherein the passage is held in a substantially horizontal direction .