Fluid sprinkling – spraying – and diffusing – Unitary injection nozzle and pump or accumulator plunger
Reexamination Certificate
2000-01-28
2001-06-26
Douglas, Lisa Ann (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Unitary injection nozzle and pump or accumulator plunger
C239S570000
Reexamination Certificate
active
06250563
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a fuel injection valve having a control chamber that is connected to an inflow duct. A pressure in the control chamber is operatively connected to a nozzle needle and the pressure in the control chamber controls the nozzle needle. A servovalve having a closing body and an associated valve seat is disposed between the control chamber and a return duct. In a closed position, in which the closing body is moved by an actuator, the closing body closes an outflow of the fuel injection valve.
Such a fuel injection valve is known from Published, European Patent Application EP 0 816 670 A1. The known fuel injection valve contains a servovalve which serves for bringing about hydraulically the opening and closing of the fuel injection valve, in particular for defining the start and end of the injection operation exactly in time. A spherical closing body is introduced in the valve chamber of the servovalve and is operatively connected to an actuator via a tappet. The closing body, together with a conical first valve seat of the valve chamber, forms a seal resistant to high pressure. When the actuator is deflected, the closing body is lifted off from the first valve seat, with the result that the servovalve opens (2/2-way valve). In another embodiment, a further conical sealing seat located opposite the first valve seat in the axial direction is disposed in the valve chamber, and, when the actuator is in the deflected state, the closing body covers the further valve seat, thus giving rise to a hydraulic stop (3/2-way valve).
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a fuel injection valve for internal combustion engines, which overcome the above-mentioned disadvantages of the prior art devices and methods of this general type, which has an improved configuration of a servovalve.
With the foregoing and other objects in view there is provided, in accordance with the invention, a fuel injection valve, including:
an inflow duct;
a nozzle body having a control chamber formed therein, the control chamber is connected to the inflow duct;
a nozzle needle disposed at least partially in the control chamber, a pressure in the control chamber being operatively connected to the nozzle needle, and the pressure in the control chamber controls the nozzle needle;
a return duct;
a servovalve disposed between the control chamber and the return duct, the servovalve has a closing body and an associated valve seat, in a closed position of the servovalve the closing body closes an outflow, the closing body has a closing head in a form of a part-sphere and associated with the valve seat, the closing body further has a closing stem merging with the closing head, the servovalve has a valve spring surrounding the closing stem that pre-stresses the closing head against the valve seat; and
an actuator for actuating the closing body.
One advantage of the invention is that the useful life of the servovalve is increased. Another advantage is the small build of the servovalve and the simple method of producing the closing body.
The special shaping of the closing body as a rotationally symmetric body is advantageous, the latter having a i termination in the form of a part circle on one end face (head) and merging in the longitudinal direction, toward the opposite end face, into a slender stem of a smaller diameter. The cross-sectional shape of the closing body is formed to be approximately mushroom-shaped.
The head of the closing body preferably has a central flattening, on which a tappet connected to the actuator rests. An enlarged effective area between the tappet and the closing body is thereby achieved, thus advantageously leading to lower wear and less risk of tilting of the closing body.
The stem of the closing body is surrounded by the valve spring which pre-stresses the closing body in a direction of the first valve seat. The compact overall size of the servovalve and stabilization of the closing body are advantageously achieved as a result.
The stem of the closing body is terminated in the form of a part-sphere, the part-sphere shape advantageously serving, together with a sealing seat, as a sealing surface.
The closing body is preferably produced from a solid sphere. This results in low production tolerances and a simple production method.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a fuel injection valve for internal combustion engines, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 4074700 (1978-02-01), Engle
patent: 5564469 (1996-10-01), Tremoulet, Jr. et al.
patent: 36 27 865 A1 (1988-02-01), None
patent: 0 615 064 A1 (1994-09-01), None
patent: 753 660 A1 (1997-01-01), None
patent: 0 816 670 A1 (1998-01-01), None
Frank Wilhelm
Gross Hartmut
Schmutzler Gerd
Wagner Joachim
Douglas Lisa Ann
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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