Fuel Injector

Details Fuel Injector Fuel Injector

1999-09-13

2001-09-04

Scherbel, David A. (Department: 3752)

Fluid sprinkling, spraying, and diffusing

Fluid pressure responsive discharge modifier* or flow...

Fuel injector or burner

C239S589000, C137S56100R, C137S56100R

Reexamination Certificate

active

06283391

ABSTRACT:

PRIOR ART
The invention is based on a component having a bore, in which at least one partial region of the component has an angle of inclination between its center axis and an axis of the bore. In one such component, known from German Published, Nonexamined Patent Application DE-OS 195 47 423 A1, the bore is embodied as an axial through bore, which centrally enters the component at a first axial end face and exits the component eccentrically to the axis of the component at a second end face remote from the first. The through bore, embodied as an angled bore, serves as a high-pressure fuel conduit in a valve holding body of a fuel injection valve for internal combustion engines, by way of which fuel is carried by a conduit at high pressure to the fuel injection valve, protruding into the engine combustion chamber. The inlet opening of the upper, obliquely extending bore portion is disposed centrally in an upper end face, while the exit opening of the second bore portion, extending in a straight line, is disposed eccentrically in a second, lower end face of the valve holding body. This is necessary so that a further blind bore, forming a spring chamber, can be made in the valve holding body in its lower region.
The angled through bore in the known valve holding body has the disadvantage, however, that in the overlapping region between the portion of the bore extending obliquely to the axis of the valve holding body and the portion of the bore extending straight relative to it, a weakening occurs in terms of the high-pressure strength of the valve holding body. The result, especially at very high pressure threshold stresses of over 1800 bar, is breakage, which can lead to the failure of the entire injection system and thus the entire internal combustion engine. Furthermore, turbulence of the fuel flowing through the overlapping region occurs at the corresponding edges of the bore, and this worsens the flow behavior to the fuel injection valve. Even with very complicated grinding methods, for instance by using abrasive grinding agents, it is hardly possible to machine this bore transition optimally, and so the course of the angled bore in the valve holding body does not meet the stringent demands made of modern injection systems.
ADVANTAGES OF THE INVENTION
The component according to the invention, having a bore that at least in part forms an angle of inclination with a partial region of the axis of the component, has the advantage over the prior art that bore overlaps or edges resulting from a kinked course of the bore can be avoided. This is advantageously made possible by providing that the bore, preferably an axial through bore, has only a single, uncurved, continuous axis and thus is embodied as a straight bore throughout. In order nevertheless to achieve a relative axial offset of the bore from the axis of the component, the component has a partial region that is displaced out of the total center axis of the component. For example by means of an offset-bent embodiment of the component, a course of the through bore as a straight bore becomes possible, and this bore can also be embodied as a stepped bore. Compared with a kinked bore course, this straight bore has the advantage that better flow behavior inside the bore can be attained. In addition, the overall pressure threshold strength of the component can be increased, since the originally critical region of the transition between the oblique and the straight bore is omitted. A further advantage of the embodiment of the component according to the invention is that the through bore in the component is very much simpler to produce. The through bore advantageously centrally enters the component at a first axial end face thereof and exits the component eccentrically to its axis at a second end face opposite the first. Alternatively, both the entrance and exit and the centricity and eccentricity of the through bore at the end faces can be transposed. An eccentric course of the bore in one of the end faces advantageously makes it possible to provide a further bore at this end face, such as an additional reception chamber for a restoring member (such as a valve spring or hydraulic piston) of an injection valve. This further bore may be placed either centrally or eccentrically in the end face of the component.
The embodiment according to the invention of the component will be described taking as an example a valve holding body for a fuel injection valve for internal combustion engines, but it is alternatively possible in all components in which a kinked bore is necessary because of a central bore entrance and an eccentric bore exit.
The size of the offset bend of the preferably cylindrical component depends on the axial offset of the bore to be made and on the position of a possible adjoining thread on the component. This adjoining thread may be provided either centrally or eccentrically to the offset bend.
Further advantages and advantageous features of the subject of the invention can be learned from the description, drawing, and claims.


REFERENCES:
patent: 1660557 (1928-02-01), Heimburger
patent: 3738576 (1973-06-01), O'Neill
patent: 5133503 (1992-07-01), Giordano et al.

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