High pressure fuel reservoir

A high-pressure fuel reservoir for a fuel injection system for internal combustion engines, which is supplied with high-pressure fuel by a high-pressure fuel pump and which has connections embodied as connection stubs, from each of the connection stubs one connecting bore discharges into the tubular body eccentrically to the axis of the tubular body. The tubular body is produced by forging, with three connecting stubs and fastening elements formed on by forging.

PRIOR ART
 The invention is based on a high-pressure fuel reservoir for a vehicle. One
 such high-pressure fuel reservoir, known from European Patent Disclosure
 EP 0 507 191, comprises a prefabricated tube onto which connection cuffs
 are slipped to connect the fuel injection valves, or the high-pressure
 line arriving from the high-pressure fuel pump. Such a high-pressure fuel
 reservoir is relatively expensive to produce and moreover, because of the
 connection parts that have to mounted on it, requires a relatively large
 amount of installation space. In addition, it must have very thick walls
 in order to withstand the high pressures under the cyclic loads to which
 it is exposed. One disadvantage here is that thick-walled bodies subjected
 to major cyclic pressure loads tend to rip apart, especially in the area
 of openings in the walls and where there are sharp-edged changes in cross
 section.
 ADVANTAGES OF THE INVENTION
 By means of the high-pressure fuel reservoir of the invention, a
 high-pressure fuel reservoir is obtained that because of the eccentric
 location of the connecting bores is especially capable of withstanding the
 cyclic loads. Because of this eccentric location, the individual loads, in
 the region of a intersection with the inner wall of the high-pressure
 reservoir, are superimposed on one another only vectorially, resulting in
 an approximately 30% reduction in the loads. This substantially increases
 the strength and thus prolongs the service life of the high-pressure
 reservoir.
 An advantageous feature is that the connecting bores discharge at a tangent
 to the inner wall of the tubular body. This further reinforces the
 aforementioned effect. To avoid abrupt cross-sectional transitions and
 thus to further reduce the partial heavy load on wall cross sections, an
 embodiment set forth herein is especially advantageous, in which the
 tubular body is shaped by forging, with connection stubs likewise formed
 by forging. This has the further advantage of requiring less installation
 shape, since the connections, because they are integral with the tubular
 body, can be made substantially smaller. In addition, the high-pressure
 reservoir is thus lower in weight.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
 In FIG. 1 of the drawing, a high-pressure fuel reservoir is shown, which
 comprises an elongated, forged tubular body 1, which on its jacket face
 has connecting stubs 2, formed by forging, for supplying four fuel
 injection valves, and which has fastening elements 3 formed onto the
 jacket face diametrically opposite the connecting stubs 2. The fastening
 elements take the form of fastening eyelets or tabs, with through holes 4
 to be made by drilling, as can be seen from the section II--II in FIG. 2.
 On its face ends 5, an axial through recess 10 (FIG. 2) forming the
 interior of the high-pressure reservoir and embodied here as a through
 bore is firmly closed. An inlet from a high-pressure fuel pump, not shown
 here, to the interior of the high-pressure reservoir is formed by an
 additional connecting stub 6 located between two fuel injection valves
 connections. On the side of the fastening elements 3, the tubular
 high-pressure reservoir can have still another connecting stub 7, into
 which a pressure sensor or a control valve, for instance, can be screwed.
 The connecting stubs 2 are provided with a screw thread 8 in the usual
 way, into which high-pressure connecting lines can be inserted tightly,
 for instance via a cone seal. These lines communicate with the interior of
 the tubular high-pressure reservoir 1, that is, the through bore 10, via
 connecting bores 11. The cross section of this recess is preferably a
 circular area but it may also have some other shape, such as oval. The
 special feature of the invention in this respect is that the connecting
 bores discharge into the through bore 10 eccentrically to the longitudinal
 axis of the through bore, with an eccentricity e. The discharge is
 preferably effected tangentially. This affords the advantage, mentioned at
 the outset, that the tension load on the wall of the high-pressure
 reservoir in the region of intersection of the connecting bores with the
 longitudinal bore is reduced because in this construction the individual
 loads are superimposed only vectorially on one another. The connections 2
 are used to connect the high-pressure fuel reservoir to electrically
 controlled fuel injection valves.
 The foregoing relates to preferred exemplary embodiments of the invention,
 it being understood that other variants and embodiments thereof are
 possible within the spirit and scope of The invention, the latter being
 defined by the appended claims.