Fluid sprinkling – spraying – and diffusing – Flow deflecting or rotation controlling means – Fluid rotation inducing means upstream of outlet
Patent
1997-03-12
1998-07-28
Weldon, Kevin
Fluid sprinkling, spraying, and diffusing
Flow deflecting or rotation controlling means
Fluid rotation inducing means upstream of outlet
2395854, 239900, F02M 6118
Patent
active
057852545
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a fuel injection valve, and in particular to a fuel injection valve for a fuel injection system of a mixture-compressing externally ignited combustion engine.
BACKGROUND INFORMATION
It is known from German Offenlegungsschrift 2,723,280 to arrange, on a fuel injection valve, a fuel breakup element in the form of a flat thin disk having a plurality of narrow curved slots, in the downstream direction from a metering orifice. The curved slots produced by etching in the disk, with their geometry, i.e., their radial width and curve length, are responsible for the formation of a fuel mist that is broken up into small droplets. The curved slots arranged in groups divide the fuel according to their geometry in the horizontal plane. The individual slot groups must be produced very precisely in relation to one another in order to achieve the breakup of the fuel in the desired manner. The curved slots have a constant opening width over the entire axial extension of the breakup element. Therefore, atomizing can only improved by varying the horizontal geometry in the radial direction of the slots in the plane of the breakup element. The fuel is atomized fully and uniformly due to the slots being arranged in groups.
ADVANTAGES OF THE INVENTION
The fuel injection valve according to the present invention has the advantage over the related art that high-quality and uniform fine atomization of the fuel is achieved without additional power consumption. This is accomplished by the injector plate provided on the fuel injection valve having at least one uninterrupted annular gap so that the swirling fuel to be sprayed forms a continuous annular jet lamella immediately downstream from the annular gap. Due to the geometry of the injector plate and the annular gap, this lamella has the shape of a truncated cone or a bell. Because of its surface tension, the fuel cone becomes thinner in its fuel film thickness in the downstream direction, i.e. with the increasing diameter, until it breaks up into minute droplets. These minute droplets have a reduced Sauter Main Diameter (SMD) compared to the related art, i.e., a smaller mean droplet diameter of the sprayed fuel; an SMD of <60 .mu.m can be achieved. As a result, the exhaust emissions of an internal combustion engine and fuel consumption can be further reduced among other things.
As an additional advantage, the arrangement according to the present invention achieves a uniform distribution of the sprayed fuel on a relatively large surface. This yields a smaller droplet packing density in the fuel spray formed after the broken-up lamellas and good mixture with the air intake stream of the internal combustion engine. In addition, the danger of droplet coagulation, i.e., recombination into larger droplets, is reduced.
The possibility of influencing the lamella angle by changing the axial annular gap height represents an additional advantage of the fuel injection valve according to the present invention. Variation of the annular gap height results, however, in negligible changes in the flow rate, since the stream separates on one side in the annular gap. Therefore the flow rate over the width of the annular gap and the lamella angle over the height of the annular gap can be adjusted separately.
Due to the radial offset of the annular gap of the injector plate in relation to the inlet into the helical depressions provided upstream from the annular gap, an S-shaped flow of the fluid is obtained in the injector plate. This provides the flow with a radial velocity component, which is not lost even at the exit. The flow is given a turbulence conducive to atomization by the "S-collision" with the flow deflectors. The flow is also given an advantageous swirl component in addition to the radial component by the swirl-promoting depressions that do not run in a completely radial direction.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a partial view of a fuel injection valve with an injector plate according to the present inventio
REFERENCES:
patent: 3128048 (1964-04-01), Denure
patent: 3915623 (1975-10-01), Wormser
patent: 4394973 (1983-07-01), Sauer et al.
patent: 4890794 (1990-01-01), Imafuku et al.
patent: 4925111 (1990-05-01), Foertsch et al.
Buehring Juergen
Heyse Joerg
Klaski Michael
Koenig Harald
Magenau Horst
Robert & Bosch GmbH
Weldon Kevin
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