Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
1999-10-07
2001-09-04
Scherbel, David A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S088000, C239S575000
Reexamination Certificate
active
06283390
ABSTRACT:
PRIOR ART
The invention is based on a fuel injection device for internal combustion engines. In a fuel injection device of this kind, which is of the unit fuel injector type and is known from EP 0 461 212, a fuel injection pump is axially combined into one component with a fuel injection valve by means of a clamping sleeve, and is inserted along with this valve into the housing of the engine. The fuel injection pump has a piston-shaped pump piston, which is driven by the cam shaft of the engine. The high-pressure fuel quantity delivered into the pump working chamber of the fuel injection pump is controlled during the pressure stroke of the pump piston by means of electric control valve, which is likewise inserted into the component of the injection pump and injection valve and is disposed there on a laterally protruding housing piece. In this connection, a fuel delivery pump sends fuel from a fuel tank by way of a fuel supply line to the fuel injection pump, which feeds into an annular chamber encompassing the clamping sleeve. This annular chamber in the housing of the engine can be connected by way of through openings in the clamping sleeve and furthermore, by way of supply conduits in the pump housing, to the working chamber of the fuel injection pump, wherein this connection can be closed off by the electric control valve. The fuel, which is delivered under high-pressure by the fuel injection pump, thereby travels by means of injection lines to the fuel injection valve and, after a particular opening pressure is exceeded, is injected there via injection openings into the combustion chamber of the internal combustion engine.
In order to protect the injection opening on the fuel injection valve from becoming clogged, and to prevent resultant quantity variations and imprecise injection jet characteristics, fuel injection devices of the unit fuel injector type have fuel filters in the fuel supply line to the fuel injection pump, which filters are comprised of annular filters or button filters embodied as woven screens. Disk filters inside the fuel injection valves are also known. These known fuel filters, however, have the disadvantage that they require additional space and also result in additional manufacture and assembly costs. Moreover, with these known fuel filters, there are problems with regard to their service life, since the effective filter area is relatively small and can therefore become rapidly clogged.
ADVANTAGES OF THE INVENTION
The fuel injection device for internal combustion engines according to the invention, has the advantage over the prior art that the filter function can be taken over by an existing component, so that no additional components are required for fuel filtration in the fuel injection device according to the invention. To that end, a multitude of filter openings are provided in the clamping sleeve, which clamps the fuel injection pump and the fuel injection valve axially against each other, in the vicinity of a fuel-filled annular chamber, which filter openings act as dirt particle filters when fuel passes through. These filter openings are advantageously disposed around the entire circumference of the clamping sleeve so that a large effective filter cross section is produced. The filter holes themselves preferably have a diameter from a 30 to 90 &mgr;m so that even small dirt particles can be reliably filtered out from the fuel. Another advantage of the filter function by means of a perforated clamping sleeve is the possibility of setting specific through-flow values by means of the disposition and design of the filter openings, without additional changes having to be made in other components. Consequently, pressure-regulating functions can be realized in a simple manner, by means of which switching times of the entire fuel injection device can be optimized and additional throttle bores can be eliminated. In this connection, is particularly advantageous to embody the filter holes in the clamping sleeve as conical, with a cross sectional reduction directed radially inward so that a flow reversal of the fuel passing through can also rinse the filter openings clear in a simple manner. Another advantage of the use of the clamping sleeve as a fuel filter is the prevention of possible assembly errors by means of incorrectly inserted or loose fuel filters, which could cause malfunctions in the operation of the fuel injection device. In addition, the fuel filter embodied by the clamping sleeve has a long service life and is very rugged.
The filter openings of the filter sleeve according to the invention are advantageously produced by means of a pulsating electron or laser beam. Each beam pulse produces a filter opening in the sleeve wall, wherein the sleeve is rotated around its axis during processing and the beam tool is moved in a linear fashion so that a helical series of filter openings are produced on the circumference of the filter sleeve. In order to prevent a burr formation on the inner wall of the bores, an elastic material (e.g. silicone) is deposited on the wall side of the filter body remote from the beam, which material evaporates when struck by a the beam during the processing phase and, by means of this vapor pressure, knocks the material cutting out of the filter opening. In order to additionally minimize a burr formation on the outer wall of the bore, the outer surface of the filter sleeve oriented toward the beam is coated with a material that prevents an adhesion of processing cuttings. This surface, which is preferably coated with manganese phosphate, thus prevents an adhesion of the blown-out material cutting.
During the production of the filter openings, different cross sections can be realized by means of the duration and design of the beam pulse and different dispositions can be realized by means of the rotation speed of the filter part, wherein among other things, slots and similar cross sectional shapes are also possible for the filter openings. In addition, the process according to the invention can also be used to produce recesses in work pieces in addition to being used to produce filter openings in filter bodies in entirely different components, where small openings are needed.
Other advantages and advantageous embodiments of the subject to the invention can be inferred from the description, the drawings, and to claims.
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patent: 4378481 (1983-03-01), Brennan et al.
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patent: 4470945 (1984-09-01), Howard et al.
patent: 4932883 (1990-06-01), Hsia et al.
patent: 5181379 (1993-01-01), Wakeman et al.
patent: 5376252 (1994-12-01), Ekstrom et al.
Brendle Peter
Eisemann Achim
Feichtinger Ernst
Kronberger Maximilian
Schneider Rainer
Greigg Edwin E.
Greigg Ronald E.
Hwu Davis
Robert & Bosch GmbH
Scherbel David A.
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