Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1998-02-09
1999-11-02
Moulis, Thomas N.
Internal-combustion engines
Charge forming device
Fuel injection system
123198B, 123198E, 411910, 70417, F02B 7700
Patent
active
059750545
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a security system for a fuel system to protect against unauthorized use. In one such arrangement, known from European Patent Disclosure EP-A1-0 629 532, a simple cap is provided, which includes an electric circuit that surrounds a magnet valve on a fuel pump. The cap and the screw connection that connects it to the fuel pump are arranged such that the screw connection is no longer accessible once the injection pump is installed. Not until the pump is removed can the cap be unscrewed and access to the magnet valve afforded. Such magnet valves in fuel pumps serve to prevent the delivery of fuel to the pump work chambers of the fuel pump when the internal combustion engine is stopped or turned off. Before the engine is turned on, such a magnet valve has to be opened. This is done by means of an electric control unit, part of which, in the known version, is located inside the cover.
If someone without authorization seeks to start the engine, this could be accomplished by manipulation of the magnet valve. However, that can be done only if the magnet valve is also accessible. The electrical circuit located under the cover prevents easy manipulation of the magnet valve from outside the cover. Via a security code and other security provisions, electrical access to the magnet valve is prevented. Mechanical access, however, could still render the magnet valve nonfunctional and in principle could put it in the open position. Hence someone would be able to steal the vehicle to which the engine belongs.
The known security system is intended to prevent this by means of the cover provided. However, that cover is embodied simply as a sheet-metal part which nevertheless can be opened by force using levers or cutting tools. In that case, once again, direct access to the magnet valve would be possible.
ADVANTAGES OF THE INVENTION
The security system according to the invention has the advantage over the prior art that releasing the connection between the cap part and the base part is fundamentally prevented. Because the cap part covers the base part in such a way that access to its fastening to the housing of the fuel pump is possible only by removing the cap part, a high level of security is assured. The embodiment of the side walls extending complementary to one another and their positive engagement with one another prevent the possibility of removing the cap part by force using tools, at least within a prescribed minimum length of time. Within the context of a specified time period, the security system can thus not be destroyed enough to allow access to the adjusting element or the function element, which by way of example may be a magnet valve. This security is especially increased by the embodiment defined herein, in which an especially close fit between the base part acting as a holder and the cap part can be attained. By another embodiment defined herein, the security system is embodied in such a way that it presents considerable resistance to chip-removing and cutting tools. The austenitic manganese steel is extremely difficult to machine in a chip-producing way and moreover is highly impact-resistant. In an advantageous further feature, the cap comprises cast steel, so that once again there are no easily-notched edges to reduce the strengths particularly of the cap part. It is especially advantageous, in accordance with another embodiment, that the side wall of the cap part is surrounded on the outside by the side wall of the base part. Thus, the cap part presents no substantial engagement faces, especially on its face end, that would allow lifting the cap by force. The gap between the side walls, which is minimized by the positive engagement, is not accessible to leverage-exerting tools.
In another advantageous feature, the screws that connect the cap part to the base part are embodied such that after the cap is secured by them, they cannot easily be loosened again. Because of the absence of the positive-engagement face, which would be operative in the opening direction, the s
REFERENCES:
patent: 4062336 (1977-12-01), Gant et al.
patent: 4209000 (1980-06-01), Ivie
patent: 4353336 (1982-10-01), Mowbray
patent: 4718828 (1988-01-01), Breeck et al.
Alvarez-Avila Carlos
Haberer Helmut
Greigg Edward E.
Greigg Ronald E.
Moulis Thomas N.
Robert & Bosch GmbH
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