Fluid sprinkling – spraying – and diffusing – Unitary injection nozzle and pump or accumulator plunger
Reexamination Certificate
1999-06-30
2001-10-02
Ganey, Steven J. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Unitary injection nozzle and pump or accumulator plunger
C239S096000, C239S533200, C239S533800, C239S102100, C123S496000, C123S504000
Reexamination Certificate
active
06296197
ABSTRACT:
PRIOR ART
The invention is based an injection valve for a fuel system of a vehicle.
One such injection valve is known from U.S. Pat. No. 5,458,293. In terms of its construction, such an injection valve can be composed of multiple function groups. A first function group includes a metering valve for the fuel, with injection openings and a valve shaft. A second function group includes an actuator as its drive mechanism. A third function group can be disposed between these first two function groups; it serves the purpose of servo assistance and can also be called a travel booster. This function group has a control chamber, which communicates hydraulically with a high-pressure reservoir via a primary throttle (inlet throttle) and can be relieved via a secondary throttle (outlet throttle) and a relief valve.
Finally, between this third function group and the actuator, a fourth function group can also be connected, assuring a hydraulic step-up of the travel distance. One example of an injection valve with all four function groups is given in German Patent DE 19 19 192 C1. This patent also addresses the object, in terms of what is known as preinjection, of making the smallest possible replicable preinjection quantities possible. U.S. Pat. No. 5,458,293, conversely, addresses not preinjection but rather the furnishing of a graduated course of the injection quantity by means of different opening stroke lengths of the closing member of an injection valve, at various supply pressures or injection pressures.
The present invention—unlike U.S. Pat. No. 5,458,293—has to do with the function group that has a control valve for servo assistance, and the object of the invention is to improve the suitability of an injection valve for the preinjection and the main injection.
ADVANTAGES OF THE INVENTION
The subject of the invention, has the following advantage:
In the preinjection, short switching times at the control valve can be attained, and the flow quantity through the control valve is limited. The invention makes it possible to construct an injection valve that is controlled by a piezoelectric actuator. Such an injection valve is suitable as a common rail injector, for example.
With the injection valve of the invention, two switching stages can be realized, with high stroke-length precision. The first axial stroke for the preinjection can be reduced sharply. This also reduces the switching time, while it becomes possible to attain a long stroke for the main injection.
Advantageous refinements are recited hereinafter, the characteristics of which can also be combined with one another, where appropriate.
In one variant, a compression spring is connected parallel to a helical spring during the traversal of another second axial stroke; in the variant, one compression spring and one helical spring are connected in series with one another. In both cases, a compact construction can be attained in that a piezoelectric actuator is used, and the two compression springs are disposed in the region between the piezoelectric actuator and the head of the control valve. If the adapter is guided on the valve tappet of the control valve, fluttering motions can be readily avoided.
REFERENCES:
patent: 4403740 (1983-09-01), Eblen et al.
patent: 4669668 (1987-06-01), Ogawa
patent: 4684067 (1987-08-01), Cotter et al.
patent: 5694903 (1997-12-01), Ganser
Ganey Steven J.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
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