Fuel injection valve

Details Fuel injection valve Fuel injection valve

1999-08-13

2001-02-13

Shaver, Kevin (Department: 3754)

Valves and valve actuation

Electrically actuated valve

Including solenoid

Reexamination Certificate

active

06186472

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a fuel injection valve.
BACKGROUND INFORMATION
Unexamined German Patent No. 195 03 821 describes an electromagnetically operated fuel injection valve having a metal base body of the valve designed in one or two parts without a nonmagnetic intermediate part. The base body includes the inlet connection, a magnetic internal pole (core) and a valve seat carrier. In addition, the base body is responsible for guiding an armature which operates a valve closing body that works together with a valve seat. In addition, the base body has a magnetic choke point which has a much smaller wall thickness than the wall thicknesses of the upstream core and the downstream valve seat carrier.
Furthermore, Unexamined German Patent No. 195 37 382 also describes an electromagnetically operated fuel injection valve having an internal core and an external magnet housing. The magnet housing is designed as a stepped housing, forming a coil space between the core and the magnet housing to accommodate a magnet coil. The coil space is sealed with a cover element above the magnet coil and with a nonmagnetic intermediate part below the magnet coil. Thus, two additional parts are needed in addition to the core and the magnet housing to close the magnetic circuit or to prevent a magnet short-circuit.
SUMMARY
The fuel injection valve according to the present invention has the advantage that it can be produced especially easily and inexpensively, although this in no way impairs the valve functions. In an advantageous manner, the internal pole and the valve jacket are shaped so that the valve jacket surrounds the internal pole at least partially radially with a distance, forming a clearance between them into which the magnet coil is inserted. The magnet coil is securely and reliably embedded because it is completely surrounded by the valve jacket in the circumferential direction, and the clearance is bordered axially above and below the magnet coil by metallic contact between the valve jacket and the internal pole. This direct metallic contact between the valve jacket and the internal pole plus the fact that the coil space is thereby closed ensure that no additional intermediate parts are necessary in an inexpensive manner that reduces the number of parts and saves on material. This design permits the best possible selection of materials for manufacturing the internal pole and the valve jacket while retaining the required magnetically soft properties.
In an advantageous manner, the internal pole of the fuel injection valve can be manufactured by extrusion, especially advantageously by cold forming. Steels with a low tensile strength (unalloyed steels) as well as steels with a high tensile strength (high-alloy steels) are suitable for cold extrusion. After cold extrusion, unalloyed steels achieve the strength values (tensile strength, hardness) equivalent to those of alloyed steels after annealing. Because of the magnetic properties of the internal pole, it may be advantageous to subsequently anneal the extruded internal pole blank. It is not necessary to consider the tensile strength, because the required strength values are achieved in any case. A major advantage of extrusion is that it requires less use of material in comparison with known turned parts, which yields definite cost advantages.
It is especially economical if, in addition to the extruded internal pole, a deep-drawn valve jacket is provided and is fixedly joined to the internal pole, forming together with the latter a metal base body which extends over the entire axial length of the valve.
Because of the metallic contact between the valve jacket and the internal pole, it is especially advantageous to provide a magnetic choke point on the internal pole, so that the magnetic circuit is closed around the magnetic choke point over the valve jacket, internal pole and armature. This eliminates the need for nonmagnetic intermediate parts.
The coil space with the magnet coil, which is consequently dry, is sealed by a ring gasket provided between the internal pole and the valve jacket, arranged on the side of the magnet coil axially opposed to the fixed connection of the valve jacket and internal pole.


REFERENCES:
patent: 4944486 (1990-07-01), Babitzka
patent: 5178362 (1993-01-01), Vogt et al.
patent: 5328102 (1994-07-01), Babitzka et al.
patent: 5655715 (1997-08-01), Hans et al.
patent: 5687468 (1997-11-01), Hans et al.
patent: 5769391 (1998-06-01), Noller et al.
patent: 5927613 (1999-07-01), Koyanagi et al.
patent: 195 03 821 (1996-08-01), None
patent: 195 03 820 (1996-08-01), None
patent: 195 37 382 (1997-04-01), None
patent: 197 12 589 (1998-06-01), None
patent: 0 278 099 (1988-08-01), None

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