Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-08-03
2001-11-20
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S470000
Reexamination Certificate
active
06318339
ABSTRACT:
The invention relates to a fuel supply line system for a fuel injection nozzle connected with the cylinder head of an internal combustion engine, having a pressure connector that communicates tightly on the inlet side with the connection piece of an inlet tube and on the outlet side is pressed axially, via a sealing face, against a seat face on the nozzle holder body of the fuel injection nozzle by means of a screw connection.
One such fuel supply line system is disclosed for instance in European Patent Disclosure EP 0 569 727 A1 and German Patent Disclosure DE 195 24 520 A1.
A problematic aspect of these fuel supply line systems is that the pressure connector, because it is screwed on, presses directly on the nozzle holder body with high contact pressure. As a result, especially at high line pressures on the order of magnitude of more than 1200 bar, cracks can occur in the nozzle holder body, because of the high stresses at the sealing face and the high internal pressures inside the fuel supply line.
These stresses are predominantly due to the high tightening moment with which the sealing face presses against the nozzle holder body.
An object of the invention is therefore to refine a fuel supply line system of this generic type in such a way that the high tightening moment of the pressure connector does not act on the sealing face and instead is maximally decoupled from the sealing face.
ADVANTAGES OF THE INVENTION
In a fuel supply line system of the type defined at the outset, this object is attained according to the invention in that a shoulder is formed on the pressure connector. When the pressure connector is screwed in, the shoulder in order to absorb the tightening moment, is pressed against a contact pressure face embodied complimentary to the shoulder on the nozzle holder body and extending annularly all the way around, and that the sealing face is disposed on a body that is provided between the pressure connector and the nozzle holder body and is deformable in a defined way by the screwing in of the pressure connector.
Because of the shoulder embodied on the pressure connector and the contact pressure face embodied on the nozzle holder body, the tightening moment with which the pressure connector is screwed into the nozzle holder body is to a certain extent “intercepted” in an especially advantageous way. The tight communication is established by the deformable body provided between the nozzle holder body and the pressure connector, and which body the sealing face is provided, and which, because of the aforementioned “interception” of the tightening moment by the shoulder on the pressure connector and by the contact pressure face on the nozzle holder body, is deformed with only a small portion of the forces generated by the screwing action when the pressure connector is screwed into the nozzle holder body.
In other words, as a result, the compressive forces that arise from the pressure connector to be screwed in with a high tightening torque are introduced not to the seat face of the nozzle holder body but rather to the annularly encompassing contact pressure face.
In terms of how the deformable body is embodied, purely in principle the most various embodiments are conceivable.
One highly advantageous embodiment provides that the deformable body is a molded part preferably comprising an easily deformable steel, which part, on a side toward the seat face, has the sealing face and on a side toward the pressure connector is embodied conically and has a sealing edge, which rests tightly against the inside of a conical recess of the pressure connector.
Such a body, because of its optimal deformability, especially in the axial direction, has especially good sealing properties.
In another embodiment it is provided that the deformable body is a sealing ring comprising an easily deformable material, such as steel. It may for instance be an O-ring. It is furthermore possible that it has a W-shaped form in section.
Both the O-ring design and the design that is W-shaped in section enable optimal sealing when an axial pressure caused by screwing the pressure connector in is exerted.
In yet another highly advantageous embodiment, it is provided that the deformable body is a ring, preferably comprising an easily deformable steel or soft iron, that is surrounded in form-locking fashion by a rubber-elastic sealing ring that engages an annularly encompassing recess embodied in the ring.
By means of this kind of deformable body, very good sealing is made possible, in particular even at relatively high tightening moments.
An object of the invention is furthermore attained by a fuel supply line system for a fuel injection nozzle inserted into the cylinder head of an internal combustion engine, having a pressure connector that penetrates a passage in the cylinder head and that communicates tightly on the inlet side with the connection piece of an inlet tube and on the outlet side is pressed axially, via a sealing face, against a seat face on the nozzle holder body of the fuel injection nozzle. A shoulder is formed on the pressure connector, when the pressure connector is screwed in, in order to absorb the tightening moment, the shoulder is pressed against a contact pressure face embodied complimentary to the shoulder on the nozzle holder body and extending annularly all the way around, and that a sealing lip that is deformable in a defined way is embodied integrally on the side of the pressure connector toward the nozzle holder body.
This fuel supply line system has the advantage in particular that a deformable body placed between the pressure connector and the nozzle holder body can be eliminated entirely, since a sealing lip that is deformable in a defined way is embodied integrally on the nozzle holder body itself.
With respect to the embodiment of the sealing lip, the most various embodiments are conceivable, purely in principle.
An especially advantageous embodiment in terms of deformability and the attendant sealing properties provides that the sealing lip, in section, has a swallowtail-like shape.
REFERENCES:
patent: 2897800 (1959-08-01), Haas
patent: 3845748 (1974-11-01), Eisenberg
patent: 4445713 (1984-05-01), Bruning
patent: 4705306 (1987-11-01), Guido et al.
patent: 4881763 (1989-11-01), Guido et al.
patent: 4938193 (1990-07-01), Raufeisen et al.
patent: 6135091 (2000-10-01), Itoh et al.
patent: 4140668 (1992-07-01), None
patent: 2266550 (1975-10-01), None
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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