Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2000-09-26
2003-07-08
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C123S456000
Reexamination Certificate
active
06588405
ABSTRACT:
PRIOR ART
The invention relates to a pump device for high pressure fuel delivery in fuel injection systems of internal combustion engines, particularly in a common rail injection system. The pump includes a pump housing, which includes a number of pump elements in which high pressure is exerted on fuel. The fuel that is acted on with high pressure is supplied by the individual pump elements to a common high pressure connecting bore by means of a high pressure conduit system.
In modern fuel injection systems of internal combustion engines, particularly in common rail injection systems of diesel engines, fuel pressures of up to 2000 bar are produced. Conventional pump devices are often unable to withstand these high fuel pressures.
In a conventional pump device, at pressures of up to 2000 bar in the delivery direction, impermissibly high stresses have been measured in the high pressure conduit system, primarily at the intersections of the individual conduits.
An object of the invention, therefore, is to optimize the high pressure conduit routing between the individual pump elements and the high pressure connection. In particular, stress peaks should be minimized at bore intersections.
In a pump device for high pressure fuel delivery in fuel injection systems of internal combustion engines, particularly in a common rail injection system, with a pump housing, which includes a number of pump elements in which high pressure is exerted on fuel, wherein the fuel that is acted on with high pressure is supplied by the individual pump elements to a common high pressure connecting bore by means of a high pressure conduit system. An object is attained by virtue of the fact that the high pressure conduit system includes a number of high pressure conduits which communicate with the pump elements and are disposed in a plane different from that of the common high pressure connecting bore in which the high pressure conduits come together. Through the disposition of the high pressure conduits in one plane, the same parts can be used for each high pressure valve. Through the disposition of the common high pressure connecting bore in a plane different from that of the high pressure conduits, the high pressure conduits can intersect with the high pressure connecting bore in an eccentric fashion. This means that the center lines of the high pressure conduits no longer intersect with the center line of the high pressure connecting bore. As a result, the stress peaks in the bore intersections are reduced. This produces the advantage that a durability of the pump housing is assured even at pressures of up to 2000 bar. Furthermore, the pump device according to the invention has the advantage that it can be inexpensively manufactured.
One particular embodiment of the invention is characterized in that at least one of the high pressure conduits passes through the outside of the high pressure connecting bore, essentially tangential to it. The plane that contains the high pressure connection is offset in relation to the plane that contains the high pressure conduits to the extent that the high pressure conduit passes through the high pressure connecting bore in an off-center, tangential fashion. This prevents dead water zones at the intersections. In addition to more favorable flow conditions, this produces the advantage that an optimal cleaning of the high pressure conduit system is assured during manufacturing. In connection with the current invention, the term “tangential” is understood to signify an option that does not absolutely have to be exercised. Manufacturing tolerances (angle, position, straightness, diameter) must be taken into consideration in the construction. Since the bores, for strength reasons, are not permitted to cut into the circumference surface of the lateral bores, structural allowances must be made for the maximal tolerance situation. A reduction of the stresses is already achieved with an off-center penetration of the bores, which does not absolutely have to be tangential.
Another particular embodiment of the invention is characterized by means of the fact that at least one of the high pressure conduits feeds into the outlet of the high pressure connecting bore, which outlet is embodied as ball-shaped. By embodying the high pressure connecting bore in the shape of a ball, bore intersections can be realized with greater angles than in bores which are produced with conventional drills. Additional indentations in the outlet of the high pressure connecting bore are also prevented.
Another particular embodiment of the invention is characterized in that the high pressure conduits pass through the blind openings in an off-center fashion. This reduces stresses.
The current invention generally produces the advantage that large diameter differences between the high pressure conduits and the high pressure connecting bore can be realized in a manner that is favorable for technical flow reasons.
Other advantages, features, and details of the invention ensue from the dependent claims as well as the subsequent description in which two exemplary embodiments are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in arbitrary combinations.
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patent: 6223726 (2001-05-01), Jung et al.
Schwarz Thomas
Streicher Bernd
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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