Fuel injector valve

Details Fuel injector valve Fuel injector valve

1988-10-13

1990-06-19

Kashnikow, Andres

Fluid sprinkling, spraying, and diffusing

Including valve means in flow line

Reciprocating

239596, F02M 6902

Patent

active

049346059

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a fuel injection valve. Known fuel injection valves operating with a valve needle as closing part have a conical sealing seat at the tip of the valve needle which open or closes a fuel flow opening in cooperation with a likewise conical valve seat face. Such a fuel injection valve, described, for example, in German Offenlegungsschrift 3,502,410, has the disadvantage that during the grinding of the sealing faces of the valve needle, burrs can be produced as a result of which the sealing effect and the quality of the flow are impaired. If these burrs are subsequently removed, deformations and edge damage of the sealing seat can occur.
Other known fuel injection valves operate with spherical closing parts which are attached to the actual valve needle (German Offenlegungsschrift 3,318,486). Apart from an additional production step necessary in manufacturing, such valves exhibit the disadvantage that they hydraulically "stick" when being lifted away from the valve seat face and thus respond with a delay. This effect is based on a more planar contact between the closing part and the valve seat face due to the relatively large radius of the sphere. When both parts lift away from one another, a short-term underpressure is produced at the sealing seat since fuel only flows with delay into the produced free volume.
In addition, a fuel injection valve is known see (German Offenlegungsschrift 3,301,501), in which a perforated disc is located downstream of the valve seat in order to improve an injected fuel jet. The fuel is injected through the holes machined in this perforated disc onto an internal wall of a processing sleeve. The actual ejection end of such a fuel injection valve forms a closing collar of the processing sleeve. It is disadvantageous in this fuel injection valve that the fuel jets generated by the perforated disc impinge at a very steep angle on the internal wall of the processing sleeve. In addition, the point of impingement is far above the ejection end of the processing sleeve. The fuel "screws" itself along the internal wall of the processing sleeve to the ejection end and an ejection occurs in the form of a cone. The liquid droplets ejected during this process are relatively large which impairs the formation of an optimum fuel/air mixture.
From German Offenlegungsschrift 3,301,501, a peg is also known which, forming a part of the perforated disc, partially projects into the valve needle body and forms an annular conduit towards the nozzle body. However, this annular conduit is not advantageously designed with respect to flow. Coming from the valve seat, the fuel is not "guided" to the perforated disc but can be collected in various dead spaces. This extends the period of time between the lifting of a valve part away from the valve seat and the ejection of fuel from the holes, the valve operates with delay.


SUMMARY OF THE INVENTION

The object of the invention is a fuel injection valve susceptible to an easy and accurate production, with burrs and other impurities impairing the flow being prevented.
The object of the invention is achieved by forming the seated portion of the valve needle as a rounding formed by a part of an outer circumference of an imaginary torus. In addition, the smooth surface contour of the valve needle and the valve seat face produces a very good correlation between the stroke of the valve needle and the volume of the fuel flowing off. Since hydraulic sticking of the valve needle on the valve seat face is largely prevented, the fuel injection valve operates with a short opening time.
It is advantageous, in particular, also to round the transient areas arranged downstream of the sealing seat to achieve a uniform fuel flow away from the sealing seat.
Particularly good atomization of the fuel is made possible if the fuel is ejected via several holes in a thin platelet clamped between the nozzle body and a processing sleeve. This platelet can be easily and inexpensively produced and, in addition, it can be made, by deep dra

REFERENCES:
patent: 1657372 (1928-01-01), Danielsson
patent: 4610424 (1986-09-01), Koppers et al.
patent: 4646974 (1987-03-01), Sofianek et al.
patent: 4650122 (1987-03-01), Kienzle

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