Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
1996-03-01
2001-06-19
Kashnikow, Andres (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S533300, C239S585100, C251S129150
Reexamination Certificate
active
06247655
ABSTRACT:
PRIOR ART
The invention relates to a fuel-injection valve for internal combustion engines. In a fuel injection valve known from EP 0,370,659, a piston-shaped valve member is guided axially displaceably in a bore of a valve body, said bore merging on the combustion space side into a blind hole via a conical region. The valve member has, at its lower end facing the combustion space of the internal combustion engine to be supplied, a conical sealing face, by means of which it cooperates with a conical valve seat on the conical region of the bore. Depending on the design of the injection valve, at least one injection duct leads off, downstream of the valve seat, from the blind hole or from the conical region of the bore in the valve body. Provided between the shank of the valve member and the wall of the bore is a pressure space which adjoins the valve seat face via a pressure duct formed by an annular gap between the valve member and bore. Furthermore, the valve member possesses in a known way, in the region of the pressure space, a pressure shoulder, on which the fuel high pressure flowing into the pressure space via a pressure conduit is applied and thus lifts off the valve member from its valve seat counter to the force of a return spring.
To form the injection jet, the inner end of the injection duct on the known injection valve is made funnel-shaped, in that the transition between the blind hole or conical region and the injection duct is rounded with a fixed radius, and this radius which, in section, extends through the longitudinal axis of the injection duct is designed in such a way that it merges tangentially into an injection jet contraction within the injection duct. At the same time, an edge remains between the rounded part and the cylindrical part of the injection duct and between the rounded part and the wall of the blind hole or of the conical region. Furthermore, this assists a contraction of the jet, reduces the throughflow rate through the injection duct and diminishes the compactness of the emerging fuel jet in a disadvantageous way.
The disadvantage of this form of the known injection port is, moreover, that the injection hole length actually effective for forming the jet is reduced as a result of the funnel-shaped entry region, in such a way that now even the length is no longer sufficient to achieve a directional injection jet. On the contrary, the injection jet of the known fuel injection valve becomes bushy and therefore does not reach a sufficient depth of penetration into the combustion space of the internal combustion engine to be supplied.
ADVANTAGES OF THE INVENTION
In contrast to this, the advantage of the fuel injection valve according to the invention, is that, as a result of the edge-free and only slight rounding of the entry regions of the injection duct, the actually effective injection hole length of the injection port is not reduced, so that a widening of the injection jet is avoided. The relatively small radii nevertheless, at the same time, already allow a uniform inflow of the fuel into the injection ports, with the result that the swirls at the entrance can be reduced considerably in comparison with conventional injection valves with non-rounded entry edges at the injection hole. In this way, a directional homogeneous injection jet is achieved by virtue of the design according to the invention of the radii at the entry region of the injection ducts.
Moreover, the notch effect is reduced as a result of the rounding of the entry edges of the injection hole, thereby leading to an increase in the high-pressure strength in the region of the tip, of the blind hole and of the injection hole to more than
2000
bar. The rounding can take place, for example, mechanically, hydraulically or electrochemically, this machining leading additionally to an increase in the tip strength, since the edge oxidation in the heart part is thereby removed.
An especially favorable shape of the injection jet is obtained when the radius in the upper entry region is 0.02 to 0.3 times and the radius in the lower entry region 0.01 to 0.05 times the diameter of the injection hole. A further improvement in the above-described formation of the injection jet is achieved when the wall thickness of the valve body, said wall thickness determining the length of the injection duct, is between 0.6 and 1.4 mm in the region of the injection duct. The measure described for the advantageous formation of as directional an injection jet as possible is feasible both on injection valves of the blind-hole nozzle type and on injection valves of the seat-hole nozzle type, in the case of blind-hole nozzles the axis of the injection duct being tilted preferably in the direction of the valve member out of a perpendicular to the wall of the blind-hole bore.
Further advantages and advantageous embodiments of the subject of the invention can be taken from the description, the drawing and the patent claims.
REFERENCES:
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Boecking Friedrich
Filiz Erguen
Douglas Lisa Ann
Greigg Edwin E.
Greigg Ronald E.
Kashnikow Andres
Robert & Bosch GmbH
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