Pumps – Three or more cylinders arranged in parallel – radial – or... – Radial cylinders
Reexamination Certificate
1999-12-03
2001-08-14
Thorpe, Timothy S. (Department: 3746)
Pumps
Three or more cylinders arranged in parallel, radial, or...
Radial cylinders
C384S298000, C384S420000, C384S903000
Reexamination Certificate
active
06273685
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a radial piston pump for generating high-fuel pressure in fuel injection systems of internal combustion engines, in particular in a common rail injection system, having a drive shaft which is supported in a pump housing. The drive shaft has an eccentrically embodied shaft portion on which preferably a plurality of pistons, disposed radially in a respective element bore are supported relative to the drive shaft, which pistons can be moved back and forth in the respective element bore by rotation of the drive shaft.
One such radial piston pump is known for instance from German Patent Disclosure DE 42 16 877. When helical gear wheels are used, the drive of the radial piston pump produces axial forces, which can be absorbed by an axial bearing disk provided with a slide bearing material. The axial bearing disk is centered in the housing and can be secured against rotation by means of two circumferential lugs that engage grooves in the pump housing. Depending on the mounting concept, it can happen that half of the pump housing has to be installed overhead with the axial bearing disk in place. In this case, it is necessary for the axial bearing disk to be fixed in its position, to prevent the bearing disk from falling out of the centering. The fixation of the axial bearing disk can be attained for instance by means of one or more supports. Attaching one or more supports, however, dictates one additional work step in assembly. Additional aids are also necessary. There is furthermore the risk that attaching the supports damage the axial bearing disk.
OBJECT AND SUMMARY OF THE INVENTION
The object of the invention is to enable fixing an axial bearing disk and the pump housing in such a way that assembly becomes simper. In particular, damage to the axial bearing disk during assembly is to be avoided.
A radial piston pump for generating high-fuel pressure in fuel injection systems of internal combustion engines, in particular in a common rail injection system. The piston pump includes a drive shaft which is supported in a pump housing and has an eccentrically embodied shaft portion on which preferably a plurality of pistons, disposed radially in a respective element bore are supported relative to the drive shaft. The pistons can be moved back and forth in the respective element bore by rotation of the drive shaft. This object is attained in that an axial bearing disk with a plurality of lugs which are disposed on the circumference and engage corresponding recesses in the pump housing is mounted in the pump housing with the aid of a retaining device. The retaining device serves to hold the axial bearing disk firmly in the pump housing, and it remains in the pump housing even after assembly.
A particular embodiment of the invention is characterized in that an annular groove is recessed in the pump housing and serves to receive a retaining ring that forms the retaining device; clamp-like protrusions are formed on this ring that fit around the lugs on the retaining ring. The annular groove serves to fix the retaining ring in the pump housing. The pump housing may either be closed, i.e. form an uninterrupted outline, or be slit in the manner of a snap ring.
A further particular feature of the invention is characterized in that the retaining device is formed by a plurality of clips fitting around the lugs, the bent ends of each clip being inserted into corresponding bores in the pump housing. In the installed state, the clips grip the lugs and thus hold them firmly in the pump housing. For this purpose, one clip would in principle suffice. Preferably, however, two or more clips are used. It is understood that there must be at least as many lugs as there are clips or clamp-like protrusions.
A further particular feature of the invention is characterized in that the bent ends of the clips have a different spacing from one another than the corresponding bores in the pump housing. As a result, it is attained that in the built-in state, the bent ends of the clips are prestressed. This prevents the clips from sliding out of the pump housing after assembly.
A further particular feature of the invention is characterized in that the retaining device is formed by a retaining disk, from whose circumference a plurality of claws are bent, which claws can dig into the pump housing when the axial bearing disk is disposed between the retaining disk and the pump housing. In this version, it is possible for the axial bearing disk to have a special external shape, such as that of a hexagon or octagon. The number of claws of the retaining disk can be adapted to the number of lugs of the axial bearing disk.
A further particular feature of the invention is characterized in that an annular groove, which is engaged by the claws bent from the retaining disk, is embodied in the pump housing. Instead, recesses can also be made in the pump housing. However, the annular groove offers the advantage of simplifying the mounting of the retaining disk.
A further particular feature of the invention is characterized in that the retaining device is formed of an elastic material, in particular spring steel. This feature offers the advantage that the retaining device can be clipped onto the pump housing in a simple way. That is, the assembly of the axial bearing disk and the retaining device can be done by hand, without using additional tools. The assembly process can also be automated, so that large numbers can be put together in a short time.
A further particular feature of the invention is characterized in that a plurality of radially extending lubricating grooves are recessed in the axial bearing disk. The lubricating grooves in the axial bearing disk make it possible for lubricant to pass out of the pump housing to the bearing running face.
A further particular feature of the invention is characterized in that the inside diameter of the pump housing in the region of the retaining devices is selected such that loosening of the retaining device is prevented. This means in detail that the clamp-like protrusions or claws are prevented from emerging from the annular groove, or the clips are prevented from emerging from the bores. In other words, the retaining device can be said to be self-securing.
Further advantages, characteristics and details of the invention will become apparent from the ensuing description, in which various exemplary embodiments of the invention are described in detail in conjunction with the drawings. The characteristics recited in the claims and mentioned in the description can each be essential to the invention individually or in arbitrary combination.
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Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Solak Timothy P.
Thorpe Timothy S.
LandOfFree
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