JP2865677B2 - Gasoline engine fuel supply system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for a gasoline engine, and more particularly, to a fuel with a branch hole for dividing fuel injected from a fuel injection valve into two spray flows. It relates to a supply device.

[Related Art] In recent years, an engine having two intake valves per cylinder (eg, a DOHC engine) in order to increase the output of the engine
Is widely spread. In a fuel supply device corresponding to such an engine, for example, as disclosed in Japanese Patent Application Laid-Open No. 55-153852, two branch passages are provided at an outlet of a fuel injection valve, and one fuel passage is provided by the branch passages. A method is adopted in which fuel injected from an injection valve is divided into two directions and fuel is supplied to corresponding intake valves.

[Problems to be Solved by the Invention] By the way, recently, in order to improve engine output and combustion efficiency, atomized fuel is atomized (for example, spray particle diameter of 200 to 100).
(approximately μm) to form a homogeneous mixture, but it has been difficult to meet this requirement in the past. The reason is that in the conventional fuel supply system in which the spray flow is divided into two directions, the spray flow is generally divided into two directions by making the spray flow into a rod shape. The film is not thin, and it is difficult to reduce the average particle size of the spray to 300 μm or less. Further, the flow direction is regulated by a branch portion formed between the two branch holes, a part of the spray ejected from the branch hole. And a part of the spray particle diameter tends to increase.

The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel supply device for a gasoline engine that divides a spray flow into two directions, in terms of engine operating conditions and valve stroke of a fuel injection valve. An object of the present invention is to form a fuel spray pattern of a hollow conical shape surely toward a branch portion without being influenced by the influence of the fuel, and to improve the responsiveness of the fuel by further reducing the particle size of the spray flow.

[MEANS FOR SOLVING THE PROBLEMS] An object of the present invention is to provide a fuel supply device for a gasoline engine that supplies fuel to an intake passage through a fuel passage that is opened and closed by reciprocating motion of a valve body. A branch portion for branching the fuel ejected from the fuel injection hole into a fuel flow in two directions having a predetermined opening angle, a swirl flow generating portion (20) provided in a fuel passage upstream of the fuel injection hole, and the swirl flow generation Swirling flow forming means comprising a plurality of fuel passages (21) arranged in a tangential direction of the swirling flow generating portion (20) at a position separated by a predetermined offset dimension from a center line of the portion (20), This is achieved by using a fuel supply device for a gasoline engine, wherein the offset dimension is set so that the spray divergence angle (θ ₂ ) of the fuel ejected from the fuel injection hole becomes 24 degrees to 40 degrees. You.

[Operation] According to the present invention, a hollow conical fuel spray pattern is reliably formed toward the branch portion without being influenced by the operating conditions of the engine or the valve stroke of the fuel injection valve. The mixture is divided into fine particles, and is atomized and injected into the intake passage. The direction of the spray flow can be set by the direction of the branch hole. As the spray forming means, a swirl type is used in which the fuel passing through the injection hole of the fuel injection valve is swirled to increase the injection divergence angle after being injected from the injection hole. The spread angle can be set arbitrarily. In addition, a hollow conical fuel spray pattern can be reliably formed toward the branch hole entrance without being affected by the operating conditions of the engine, and the increase in particle size due to the adhesion to the wall surface can be reduced.

By forming the branch hole into an elliptical cross section as in claim 2, the spray flow injected from the branch hole has a flat fan-shaped spread with a large spread in the long axis direction and a small spread in the short axis direction. Therefore, by setting the long axis of the oval cross section passage along the air flow flowing through the intake passage on the intake passage wall surface, the spray flow is not deflected to the wall surface side of the intake passage by the force of the air flow. And the mixture can be further homogenized, and the responsiveness of the fuel system can be improved.

Example An example of the present invention will be described with reference to the drawings.

FIG. 1A shows an embodiment of the present invention. In the present embodiment, a swirl type injection valve 1 is used which adds a swirling flow to fuel and jets out from an orifice. At the tip of the injection valve 1, an adapter 2 having two branch holes 3 is attached. By providing the branch holes 3, a spray flow having a small particle diameter can be formed in two directions. The adapter 2 has a disk-shaped tip shape or a cylindrical cap shape, and is fixed to the fuel injection valve 1 by "caulking" or press-fitting and metal flow. Stainless steel, brass or the like is used as the material. Injection valve 1 with gasoline resistant resin
It may be integrally molded with. As shown in FIG. 1c, the branch hole 3 is formed in a so-called elliptical elongated hole shape in which both ends of a rectangle are rounded. If the width of the oval branch hole 3 is B and the length is L, the width of the oval branch hole 3 is set narrow so that the relationship of B <L is satisfied. The fuel spray formed in this manner is split into two spray flows at the branch holes 3 and injected into the intake passage of the engine.

FIG. 2 shows the principle of operation for generating a swirling flow. As shown in FIG. 2 (b), a swirling flow generating part (part of the fuel passage) 20
A plurality of fuel passages 21 are disposed at a position δ (swirler offset) away from the center line of the swirl flow generator 20 in the tangential direction of the swirl flow generator 20, and the fuel is sent from the fuel passage 21 to the swirl flow generator 20 to generate a swirl flow. The wake spray can be spread and formed. The spray spread angle θ ₂ can be arbitrarily changed by controlling the swirling speed component (adjusting the swirler offset δ).

FIGS. 3 and 4 show the relationship between the spray divergence angle θ ₂ and the spray average particle diameter. FIG. 3 shows that the spread angle θ ₁ of the branch portion 2a is 24
And degree constant, the experimental data in the pintle type of examination of the degree of mist average particle diameter by changing the theta _2, the particle diameter becomes smaller as theta ₂ increases. However, if θ _{2 is set} to 40 degrees or more, the spray gathers at the end of the ellipse of the branch hole 3 to form four rod-like sprays, so that the particle size increases.
Is ₂ when greater than theta ₁ takes note that there is a limit. Further, the spray divergence angle theta ₂ is above confluence (coalescence) is occurs particle size becomes large in the following 24 degrees. FIG. 4 shows experimental data of the swirl type. When θ ₁₂ is fixed at 24 degrees and θ ₂ is reduced, the merging of the sprays (coalescence) occurs as in the case of the pintle type, and the particle size increases.

When an injection valve of the type that spreads the liquid film by swirling flow as in this embodiment is used as the spray forming means, the ambient temperature becomes
Even when the temperature is as low as 30 ° C., a spray having a smaller particle size can be formed as compared with the pintle type.

Next, the shape of the spray flow ejected from the branch hole 3
This will be described with reference to the drawings. FIG. 5A shows the spray flow when the elongated branch hole 3 is viewed from the direction of arrow A. The spray flow viewed from this direction has a flat shape because the branch hole 3 is narrow. Fifth
FIG. 2B shows the spray flow when the elongated branch hole 3 is viewed from the direction of arrow B. The spray flow viewed from this direction spreads in a fan shape because the branch hole 3 is elongated in one direction. As described above, two flat fan-shaped spray flows are formed by the two branch holes 3. Here, the spread angle of each spray flow in the flat direction is θ _s1 , the spread angle in the longitudinal direction is θ _s2 , and the angle between the two spray flows is θ _s3 . However, if the long axis of the elliptical cross-section passage is set on the intake passage wall surface along the air flow flowing through the intake passage, the flat fan-shaped spray flow will be directed in a direction that is difficult to receive the air flow. Can be prevented from being forcibly swept away by the force of the air flow to the wall surface side of the intake passage, and the fuel spray can be directly sent to the target position without adhering to the wall surface.

FIG. 6 shows how fuel is sprayed in the intake passage 8 when a conventional fuel supply device is used. In order to improve the responsiveness of the fuel system, it is necessary to supply fuel when the intake valve 6 is open. In this case, when the engine speed is increased and the air flow velocity in the intake passage 8 is increased, the area of the spray flow that is conventionally received by the air flow is large, so that the spray flow is bent by the air flow and adheres to the inner wall of the intake passage 8. Therefore, the fuel flowing into the cylinder 7 may flow in a liquid state, which is a factor that hinders the formation of a homogeneous mixture.

As shown in FIGS. 7A and 7B, in the present embodiment, the narrow spray angle θ _s1 side of the flat spray flow ejected from the fuel injection valve 1 through the branch hole is connected to the air passage 8. A wide spray angle θ _s2 is set on the intake passage wall so that the wide spray angle θ _s2 is parallel to the air flow in the air passage 8, that is, the long axis of the oval cross-section passage is along the air flow flowing through the intake passage. Then, as described above, the flat fan-shaped spray flow is directed to a direction that is hardly affected by the air flow. In this way, the spray flow can be prevented from being bent by the air flow as much as possible, and the path of the spray flow can always be properly maintained, so that the fuel is less likely to adhere to the wall surface of the intake passage 8 and the fuel is immediately transferred to the cylinder 7.
And the evaporation is promoted.

[Effects of the Invention] According to the present invention, a hollow cone-shaped fuel spray pattern can be reliably formed toward a branch portion without being influenced by engine operating conditions or the valve stroke of a fuel injection valve, and the injected fuel can be formed on a wall surface. A fuel spray with excellent atomization (for example, a spray of about 100 μm) can be sent without adhering to the fuel, so that a fuel with good responsiveness can be supplied. Therefore, atomized fuel can be uniformly supplied from the two intake valves into the cylinder, so that a homogeneous air-fuel mixture can be supplied into the cylinder, which has the effect of improving engine performance (output and fuel efficiency). According to the second and third aspects, the fuel can be directly sent to the target position without being affected by the air flow, so that an appropriate fuel supply can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention, and an explanatory diagram showing a positional relationship and dimensions of an adapter. FIG. 2 is an explanatory view of the operation of the swirling flow forming means. FIG. 3 is an explanatory diagram showing the relationship between the spray particle diameter and the fuel spray spread angle θ ₂ when the spread angle θ ₁ = 24 degrees is constant, and is pintle type data. FIG. 4 is an explanatory diagram showing the relationship between the spray particle diameter and the fuel spray spread angle θ ₂ , similarly to FIG. 3, and is swirl-type data. FIG. 5 is an explanatory view showing the shape of the fuel spray flow by changing the direction of the branch hole. FIG. 6 is an explanatory view showing a conventional problem. FIG. 7 is an explanatory view of the operation when applied to a two-intake valve type cylinder. [Explanation of Symbols] 1 ... Fuel injection valve, 2 ... Adapter, 2a ... Branch section, 3
... branch hole, 6 ... intake valve, 7 ... cylinder, 8 ... intake passage

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Mineo Kashiwaya 2520, Oaza Takaba, Katsuta-shi, Ibaraki Prefecture Sawa Plant, Hitachi, Ltd. (56) References JP-A-62-131969 (JP, A) JP-A Sho JP-A-62-174563 (JP, A) JP-A-57-46062 (JP, A) JP-A-59-70871 (JP, A) JP-A-55-64151 (JP, A) A) Fully open 1986-149772 (JP, U) Fully open 1988-63573 (JP, U) Fully open 1-179171 (JP, U) Fully open 1986-164470 (JP, U) Fully open 1 -105768 (JP, U) Fully open sho 61-33966 (JP, U) Fully open sho 62-105363 (JP, U) Fully open flat 1-148059 (JP, U) Tokubo Sho 62-3313 (JP, B2 ) Tokuoyake Akira 61-54948 (JP, B2) real public Akira 60-1267 (JP, Y2) (58 ) investigated the field (Int.Cl. ⁶ , DB name) F02M 61/18 F02M 69/04 F02M 61/06 F02M 51/08 F02M 51/06

Claims (2)

(57) [Claims] 1. A fuel supply device for a gasoline engine for supplying fuel to an intake passage through a fuel passage opened and closed by reciprocating movement of a valve body, wherein fuel injected from a fuel injection hole formed at an outlet of the fuel passage is supplied. A bifurcation branching into two directions of fuel flow having a predetermined opening angle; a swirl flow generating unit (20) provided in a fuel passage upstream of the fuel injection hole; and a center line of the swirl flow generating unit (20). The swirling flow generating section (20) at a position separated by a predetermined offset dimension
Swirling flow forming means comprising a plurality of fuel passages (21) arranged in a tangential direction of the fuel injection port, and a spray divergence angle (θ ₂ ) of the fuel ejected from the fuel injection holes.
Wherein the offset dimension is set so as to be 24 to 40 degrees. 2. The branch portion according to claim 1, wherein the branch portion has two branch holes, each of the branch holes has an oval cross section perpendicular to the axis thereof, and the respective long axes are formed parallel to each other. A fuel supply device for a gasoline engine, comprising: