Fuel injection valve

Details Fuel injection valve Fuel injection valve

1991-03-28

1992-07-21

Kashnikow, Andres

Fluid sprinkling, spraying, and diffusing

Including valve means in flow line

Reciprocating

239900, F02M 5106

Patent

active

051315998

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention is based on a fuel injection valve for internal combustion engines as set forth hereinafter.
In the case of a well-known fuel injection valve of this type (DE-OS 35 40 660 A1), the valve needle has a ring-shaped shoulder stop in the area between a valve needle guide in the valve space and the clamping of the valve needle in the armature; this shoulder stop works in conjunction with a stop ring, which represents the stroke stop, in the valve chamber, the bore of which is less than the external diameter of the shoulder stop and which covers the valve space. The stop ring is positioned in the valve chamber in such a way that when the shoulder stop rests on the stop ring between the front faces of the magnet core and the armature, which face one another, a residual air gap remains. The needle valve return spring, formed as a cylindrical compression spring, is housed in the hollow cylindrical interior of the magnet core, and rests in a cavity at the front end of the armature. By screwing the setting tube into or out from the magnet core, the pretensioning of the return spring can be altered independently of the valve needle stroke, and thus the dynamic through-flow of the fuel injection valve can be set.
The ring-shaped stroke stop for the valve needle has the disadvantage that where the valve needle is not in precise alignment, the arresting face of the ring shoulder on the stop ring changes from ring-shaped to sickle-shaped; thus the valve needle stroke does not conform to the stroke set, and as a result the amount of fuel injected varies. In order to largely avoid this, the valve needle has two large-diameter guide sections, placed at a relatively large distance from one another, which slide along the interior wall of the valve space. In order to enable the axial through-flow of fuel, these guide sections are flattened on the side. These construction measures necessitate not only increased expenditure in manufacture, but also require a minimum length of the valve needle section to be in the valve space, so that it is not possible to go below a certain axial construction length of the fuel injection valve.


ADVANTAGES OF THE INVENTION

The fuel injection valve which is the subject of this invention has the advantage that whilst retaining the setting facility for the needle valve return spring, a central stroke stop with a central stop point is realized; this stroke stop lies in the axis of the valve chamber. The arresting face of the valve needle is thus always dot-shaped, even when the valve needle is not exactly aligned, so that no alteration of the stroke arises during the opening of the valve needle. The amount of fuel injected is thus largely constant. Since the valve needle stroke is largely unaffected regarding any deviation of the valve needle axis from the valve chamber axis, the valve needle does not require additional guides in the valve space, but can make do with the guidance provided by the armature and the centering in the valve seat. The manufacturing costs of the fuel injection valve is thus considerably reduced. By means of the measures listed herein, advantageous developments and improvements of the fuel injection valve mentioned are possible.
If, in accordance with a preferred design form of the invention, the valve needle fixed in the armature is led through the armature by the end section which faces away from valve opening, so that on the opening stroke the valve needle stops with its front end directly on the cross link, then the situation achieved will be that the low retentivity components are not subjected to any mechanical stresses by the stroke stop. Thus separate surface treatment of these components can be dispensed with. The valve needle however, must be hardened so that it can withstand the mechanical stresses of the stop.
A further simplification of manufacture of the fuel injection valve which is the subject of this invention is achieved by the armature having a concentric blind hole which is open towards the magnet core, the retur

REFERENCES:
patent: 4232830 (1980-11-01), Casey et al.
patent: 4360161 (1982-11-01), Claxton et al.
patent: 4887769 (1989-12-01), Okamoto et al.

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