Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2001-07-27
2002-12-31
Miller, Carl S. (Department: 3754)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S509000
Reexamination Certificate
active
06499468
ABSTRACT:
PRIOR ART
The invention is based on a fuel injection valve for internal combustion engines according to the preamble to claim
1
. A fuel injection valve of this kind has been disclosed by the published, non-examined German patent disclosure DE-OS 2 303 506. The fuel injection valve has an associated valve body which can be comprised of a number of parts. The valve body tapers toward the combustion chamber so that at least one annular shoulder is embodied on its circumference surface and rests against a contact surface embodied in the receiving bore. The valve holding body has an annular groove embodied on it, in which a support element is disposed, which is embodied as a snap ring that is open in at least one location on its circumference. The snap ring is dimensioned so that it protrudes with approximately half of its thickness beyond the valve holding body. At the end of the receiving bore remote from the combustion chamber, there is a clamping element embodied as a union nut which encompasses the valve holding body and, with its external thread, engages in an internal thread embodied on the circumference surface of the receiving bore. At the end of the union nut oriented toward the contact surface, there is a hollow embodied on the inside, which covers over the snap ring. As a result, the union nut is supported against the valve holding body by means of the snap ring and can therefore clamp the valve body with the annular shoulder against the contact surface. Due to a tapered design of the hollow in the union nut, when being clamped in the axial direction, the snap ring is pressed radially against the valve holding body so that the snap ring securely engages the valve holding body. The relatively deep annular groove containing the snap ring represents a weakening of the valve holding body because of the excess stresses brought about by the stress concentration. As regards future fuel injection valves with even higher injection pressures than are currently customary, strength problems can therefore arise in the vicinity of the annular groove. Due to the circular cross section of the snap ring, essentially a linear contact occurs when it is clamped radially against the valve holding body, which leads to high surface pressures and therefore to an additional weakening in this area.
ADVANTAGES OF THE INVENTION
The fuel injection valve for internal combustion engines according to the invention, with the characterizing features of claim
1
, has the advantage over the prior art that due to the support element having a cylindrical surface on its inner circumference, when it is radially clamped against the valve holding body, there is a larger contact surface, which permits there to be a low surface pressure. In an embodiment according to the dependent claims
2
to
6
, the outer circumference surface of the support element and the inner circumference surface of the clamping element are embodied conically, as a result of which during clamping, a radial force is exerted on the support element, which is embodied as radially elastic. The surface with which the support element contacts the valve holding body can be embodied as very large so that the surface pressure required for fixing the valve holding body turns out to be correspondingly low.
In order to dispose the support element in a definite position in relation to the valve holding body, it is useful to dispose it in an annular groove according to the dependent claims
7
and
8
. As a result of the large contact surface of the support element, a depth of the annular groove of a few tenths of a millimeter is sufficient, wherein the annular groove is used essentially to fix the position of the support element before installation of the fuel injection valve in the internal combustion engine. The force transfer in the axial direction takes place by means of the force that can be transferred by means of the conically extending circumference surface with adhesion of the support element on the valve holding body produced by the contact pressure. Due to the only slight narrowing of the wall region by the flat annular groove, there is only a very slight weakening of the valve holding body in this region so that the valve holding body can withstand significantly higher injection pressures. Moreover, it is not necessary to harden the region of the annular groove in the valve holding body in a separate, costly process of the kind that is required when clamping with the aid of a snap ring and the annular groove can be produced at the end of the manufacturing process by means of a simple and inexpensive turning process.
REFERENCES:
patent: 2897800 (1959-08-01), Haas
patent: 4066213 (1978-01-01), Stampe
patent: 4589596 (1986-05-01), Stumpp et al.
patent: 6009856 (2000-01-01), Smith, III et al.
patent: 6116218 (2000-09-01), Sato et al.
patent: 6178950 (2001-01-01), Stockner et al.
patent: 6186123 (2001-02-01), Maier et al.
patent: 6192870 (2001-02-01), Lambeth
patent: 3908796 (1989-12-01), None
patent: 447 237 (1936-05-01), None
patent: 764 877 (1957-01-01), None
Egeler Hansjoerg
Ellwanger Klaus
Ferraro Giovanni
Greigg Ronald E.
Miller Carl S.
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