Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Patent
1988-08-17
1990-03-20
Kashnikow, Andres
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
F02M 6106
Patent
active
049094467
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a fuel-injection nozzle for an internal-combustion engine.
BACKGROUND OF THE INVENTION
A standard fuel-injection nozzle for an internal-combustion engine has a nozzle body formed with a bore in turn formed with a valve seat centered on an axis and tapered axially in a fuel-flow direction. This seat has relative to the direction an annular downstream edge. An axially displaceable valve needle has a surface engageable with and complementary to the seat and is formed with a throttle pin normally projecting axially into the bore past the seat edge. This needle lifts against the flow of fuel through the nozzle off the seat to permit the fuel to flow to the respective cylinder of the engine.
Such injection nozzles of this generic type have the advantage that the throughput cross section in the nozzle bore hole, which throughput cross section is formed by means of a flattened portion at the throttle pin, tends to gum up less than an annular gap between a fully cylindrical throttle pin and the nozzle bore. In a known injection nozzle of the generic type mentioned in German patent document No. 3,326,468 the flattened portion at the throttle pin is arranged so as to be inclined relative to the nozzle axis, so that the desired effect of an increasing pass-through cross section is produced until the emergence of the throttle pin from the nozzle bore. However, it is difficult to maintain the prescribed angular position of such a flattened portion in industrial-scale production and it can only be checked at increased cost, since the reference points must be maintained with extreme accuracy.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved fuel-injection nozzle for an internal-combustion engine.
SUMMARY OF THE INVENTION
These objects are attained according to this invention by forming the pin of the needle with a pair of separate flats extending substantially parallel to the axis and spaced from the bore downstream of the seat edge. These flats terminate at respective upsteam ends at edges lying generally in planes perpendicular to the axis and axially spaced from each other.
This system has the advantage that an enlargement of the preferred pass-through cross section in the nozzle bore hole is achievable during the initial lift of the valve needle with steps which can be controlled and monitored in a favorable manner during production.
Two flattened portions of the throttle pin can be spaced at different distances relative to the nozzle axis, i.e. they can be ground in different depths, so that to the determined engine types in optimum fashion. In this case, the two flattened portions can be arranged so as to be offset relative to one another by an angle, preferably 180.degree., and can be constructed so as to have different lengths. This has the advantage that the radial forces exerted on the throttle pin by the fuel can be compensated to a great extent in the lift area in which the two flattened portions are effective.
In many cases, it can also be advantageous to arrange the two flattened portions axially one after the other and to let them pass into one another at a stepped edge. If necessary, more than two, e.g. three, flattened portions can be provided one after the other so that two transition steps are produced. In order to have a compensation of radial forces in this case, as well, it is further suggested to arrange another flattened portion, in addition to the flattened portions which are arranged axially one after the other, which flattened portion is preferably offset relative to the latter by 180.degree.. But the flattened portions which are arranged axially one after the other can, of course, also be provided solely by themselves. In addition, one or more flattened portions can also be arranged diagonally relative to the nozzle axis.
DESCRIPTION OF THE DRAWING
The above and other objects, features, and advantages will become more readily apparent from the following, reference being made to
REFERENCES:
patent: 2263197 (1941-11-01), Tabb et al.
patent: 4082224 (1978-04-01), Mangus
patent: 4540126 (1985-09-01), Yoneda et al.
patent: 4591101 (1986-05-01), Fortnagel
Eblen Ewald
Giersch Rolf J.
Hofmann Karl
Kashnikow Andres
Robert & Bosch GmbH
Striker Michael J.
Weldon Kevin P.
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