Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
2000-04-25
2001-08-14
Douglas, Lisa Ann (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S585500
Reexamination Certificate
active
06273346
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to injectors for injecting fuel in the fluid state, and in particular in the liquid state, and designed to inject the fuel directly into a combustion chamber of a controlled ignition engine. It is particularly applicable to injecting gasoline, but it can also be adapted to other liquid fuels, such as alcohol-based fuels, and liquefied petroleum gas.
Direct injection injectors are already known comprising an injector body containing a needle that is axially movable by electrical control means (often constituted by a coil) and terminated by a shutter element, often of hemispherical shape, that co-operates with a seat for passing fuel. The needle is movable between a first axial position in which the shutter element bears against the seat, and a position in which it is spaced apart therefrom.
The stresses imposed on the injector for direct injection are much greater than those imposed for indirect injection into the manifold. It is necessary simultaneously to limit the penetration depth of the fuel jet, e.g. to avoid wetting the walls of the chamber, and to provide mixing between air and fuel that is as intimate as possible for better combustion, and to do this even though the time available for injecting fuel is very short.
To achieve this result, attempts have already been made to impart turbulent motion to the fuel.
Patent application FR 98/00554 describes an injector having a chamber for putting the fuel into rotation about the axis of the shutter element, which chamber is situated upstream from the seat and is defined between a plurality of elements.
SUMMARY OF THE INVENTION
The present invention seeks in particular to provide a fuel injector that satisfies practical requirements better than previously known injectors, in particular in that it causes the fuel to be set into rotation by using means that are simple to implement, but nevertheless highly effective. The invention seeks in particular to reduce the “dead” volume that the injected fuel occupies without being set into rotation when the needle begins to open.
To this end, the invention provides an injector comprising a one-piece element fixed in the downstream portion of the body, in which element there are formed the seat, the spray orifice, and a hole for slidably guiding the needle, said element being dualcone-shaped or diabolo shaped so as to co-operate with said downstream portion of the body to define a fuel feed chamber having bores putting the chamber into communication with said hole immediately upstream from the seat and opening out tangentially into the hole, and passages for feeding the chamber.
The dead space is thus restricted to the small volume annular zone situated between the cylindrical portion of the needle and the circular bearing line on the seat.
In addition, the use of holes of circular cross-section, usually two to ten in number, presents the advantage of reduced head loss, the circular cross-section being that presents the greatest hydraulic radius at given cross-sectional area.
The holes can be in a plane orthogonal to the axis of the needle. Nevertheless, it is possible for them to slope from upstream to downstream. This possibility gives a degree of freedom in addition to those concerning the number and the diameter of the holes. A single turned blank can thus be adapted to different injectors.
The above characteristics and others will appear better on reading the following description of particular embodiments, given as non-limiting examples. The description refers to the accompanying drawing.
REFERENCES:
patent: 5288025 (1994-02-01), Cerny
patent: 19625059 (1998-01-01), None
patent: 2773851 (1998-01-01), None
Croche Richard
Estevenon Christine
Douglas Lisa Ann
Larson & Taylor PLC
Sagem SA
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