Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
1999-11-03
2001-01-09
Morris, Lesley D. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
C239S585100, C251S129150
Reexamination Certificate
active
06170767
ABSTRACT:
BACKGROUND INFORMATION
The present invention is based on a fuel injection valve. German Published Patent Application No. 33 14 899 has already disclosed an electromagnetically actuable fuel injection valve in which, for electromagnetic actuation, an armature coacts with an electrically energizable magnet coil, and the linear stroke of the armature is transferred via a needle valve to a valve closure element. The valve closure element coacts with a valve seat surface in order to constitute a sealing fit. The valve needle is acted upon in the spray discharge direction by a first return spring, so that when the magnet coil is not energized, the valve closure element is held in sealing contact against the valve seat surface. The armature is not immovably joined to the valve needle, but rather is held, by a second return spring acting opposite to the spray discharge direction and in the linear stroke direction of the armature, against an entraining piece of the valve needle. When the linear stroke movement of the armature occurs, the valve needle is therefore entrained by the armature via the entraining piece, so that the valve closure element lifts off from the valve seat surface in order to open the fuel injection valve. Once the armature comes to a stop against the stop surface provided, after the linear stroke movement is complete, the valve needle can still move slightly toward the first return spring by the fact that the entraining piece lifts off from the armature. In this context, the movement direction of the valve needle is reversed by the first return spring. The armature bounces back slightly from the stop surface, its movement direction being reversed by the second return spring. The valve needle and the armature then strike against one another moving in opposite directions, and the kinetic energy of the two-mass, two-spring system is dissipated. Because of the kinematic separation of the armature and the valve needle, bouncing of the valve needle and the armature is thus greatly reduced by comarison with a usual fuel injection valve having the armature and valve needle immovably joined. The metering accuracy of the fuel injection valve can thereby be improved.
When the fuel injection valve known from German Published Patent Application No. 33 14 899 is closed, the armature also lifts off from the entraining piece of the valve needle when the valve needle is abruptly decelerated by impact of the valve closure element against the valve seat surface. The armature then moves toward the second return spring, which moves the armature back opposite to the closing direction until the armature is once again resting flush against the entraining piece of the valve needle. Bouncing of the fuel injection valve is thus greatly decreased in the closing direction as well.
In the fuel injection valve known from German Published Patent Application No. 33 14 899, however, there exists the disadvantage that the armature is guided in unsatisfactory fashion on the valve needle or on the entraining piece of the valve needle. Guidance is accomplished by the fact that the entraining piece of the valve needle is inserted into a corresponding bore of the armature. Because of the inaccuracy of the guidance, the effectiveness of the above-described debouncing of the fuel injection valve is therefore limited. In addition, the flow connection for the fuel in the region of the cup-shaped armature is attained in unsatisfactory fashion. Passthrough openings for the fuel are provided in the peripheral region of the bottom of the cup-shaped armature. The passthrough openings are arranged so that relatively high flow resistance for the fuel results, with the risk of creating undesirable turbulence.
SUMMARY OF THE INVENTION
The fuel injection valve according to the present invention has the advantage that friction between the armature and the valve needle is greatly reduced. At the same time, precise guidance of the valve needle on the armature, and conversely of the armature on the valve needle, is achieved. As a result of the at least one slide bearing according to the present invention between the armature and the valve needle, the kinematics of the two-mass, two-spring system is considerably improved, thus resulting in a fuel injection valve with particularly little bounce. At the same time, a particularly economical solution is arrived at, since the balls of the at least one slide bearing can be manufactured in particularly favorable fashion as a mass-produced product. The balls can be manufactured from hard bearing steel, which can be pressed into the soft ferromagnetic metal of the armature in a manner that is simple in terms of production engineering. The fact that the diameter of the balls can be produced accurately results in precise guidance of the valve needle on or in the armature.
According to a preferred embodiment, the armature has a stepped bore into which the balls of the two slide bearings that are provided can each be inserted at the ends. A passage provided between two enlargements of the stepped bore of the armature that receive the balls of the slide bearings allows the fuel to flow centrally through the armature, so that provision for the passage of fuel is made in particularly simple fashion with no need to provide additional bores, grooves, or flattened areas in or on the armature. At the same time, the fuel provides particularly effective lubrication of the balls of the slide bearings.
The enlargements of the stepped bore of the armature that receive the balls of the slide bearings can be closed off, after the balls have been inserted, by an edging of preferably annular configuration, in such a way that the balls cannot escape from the enlargements. The edging can be implemented in particularly simple and economical fashion in terms of production engineering, since the armature is preferably made from a ferromagnetic soft iron and is therefore relatively easy to work.
If the diameter of the balls of the slide bearings is substantially the same as the diameter of the valve needle that is of cylindrical configuration at least in this region, there results the advantage that the balls surround the valve needle in closely mutually adjacent fashion, so that the balls touch one another. The inside diameter of the slide bearing is then precisely defined by the diameter of the balls, inaccuracies in the production of the bore being compensated for by the armature.
If the valve needle has, as a stop for the balls of the slide bearing, a thickening with a continuously tapering transition segment whose radius of curvature is substantially the same as the radius of the balls, this has the advantage that the balls come to a stop against the thickening in relatively soft fashion.
REFERENCES:
patent: 1878749 (1932-09-01), Abramson
patent: 4964389 (1990-10-01), Eckert
patent: 5058625 (1991-10-01), Kaiser et al.
patent: 5088467 (1992-02-01), Mesenich
patent: 5890477 (1999-04-01), Nazare
patent: 6073911 (2000-06-01), Reiter
patent: 26 13 664 (1977-10-01), None
patent: 33 14 899 (1984-10-01), None
patent: 63 198769 (1988-08-01), None
patent: 4-209964 (1992-07-01), None
Fischer Georg
Herold Stefan
Kenyon & Kenyon
Morris Lesley D.
Robert & Bosch GmbH
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