Pumps – Three or more cylinders arranged in parallel – radial – or... – Radial cylinders
Reexamination Certificate
1999-09-13
2001-05-01
Freay, Charles G. (Department: 3746)
Pumps
Three or more cylinders arranged in parallel, radial, or...
Radial cylinders
C417S568000
Reexamination Certificate
active
06224351
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a radial piston pump for high-pressure fuel delivery in fuel injection systems of internal combustion engines, particularly in a common rail injection system. A drive shaft is supported in a pump housing and is embodied as eccentric or has cam-like projections in the circumference direction, and preferably has a number of pistons that are each disposed in a respective element bore. The pistons are situated radially in relation to the drive shaft, and can be set into a reciprocating motion in the radial direction inside the respective element bore through the rotation of the drive shaft in order to aspirate fuel by way of an intake conduit in which an intake valve is disposed, into a cylinder chamber that is defined by the piston in the element bore and is connected to a high-pressure conduit in which a high-pressure valve is disposed, wherein the element bore is disposed together with the intake conduit and the high-pressure conduit in an element head.
A radial piston pump of this kind is known from DE 42 13 798 A1. With the known radial piston pump, the high number of high-pressure sealing points has turned out to be disadvantageous.
OBJECT AND SUMMARY OF THE INVENTION
An object of the current invention is to reduce the number of high-pressure sealing points in the known radial piston pump. The radial piston pump according to the invention should withstand a pump-side peak pressure of up to 2000 bar. In addition, the radial piston pump according to the invention should be inexpensive to manufacture.
In a radial piston pump for high-pressure fuel delivery in fuel injection systems of internal combustion engines, particularly in a common rail injection system. A drive shaft is supported in a pump housing and is embodied as eccentric or has cam-like projections in the circumference direction. A number of pistons that are each disposed in a respective element bore, are situated radially in relation to the drive shaft, and can be set into a reciprocating motion in the radial direction inside the respective element bore through the rotation of the drive shaft in order to aspirate fuel by way of an intake conduit in which an intake valve is disposed. The fuel is aspirated into a cylinder chamber that is defined by the piston in the element bore and is connected to a high-pressure conduit in which a high-pressure valve is disposed. The element bore is disposed together with the intake conduit and the high-pressure conduit in an element head, an object is attained by virtue of the fact that the element bore is embodied in the element head as a blind bore from which the intake conduit and the high-pressure conduit lead. The embodiment of the element head as a blind hole element head reduces the number of high-pressure sealing points in comparison to the known radial piston pump. The simple construction also reduces the number of individual parts required. In the embodiment according to the invention, the soft seal concept can be eliminated in the high-pressure region. This produces a very high degree of functional reliability.
Furthermore, the element head of the radial piston pump according to the invention can be separately tested with a hydraulic ram. Another advantage arises from the fact that the element head can be pre-assembled as a subassembly. The pre-assembled element head can be mounted on the housing in a simple manner. This results in a very high degree of process reliability during assembly. An additional advantage lies in that the invention can be transferred to the known radial piston pump without fundamentally changing the housing concept.
A particular embodiment of the invention is characterized in that the intake conduit and the high-pressure conduit are disposed essentially perpendicular to the element bore. This simplifies the positioning of tools during manufacturing. The assembly is also simplified.
Another particular embodiment of the invention is characterized in that the intake conduit and the high-pressure conduit are flush with one another. This produces a further simplification in the production of the radial piston pump according to the invention. A part of the intake conduit and of the high-pressure conduit can be produced by means of a single bore which extends perpendicular to the element bore.
Another particular embodiment of the invention is characterized in that two bores are provided in the element head for the high-pressure valve and for the intake valve and these bores are flush with one another as well as with the intake conduit and the high-pressure conduit. This results in a simple, symmetrical design of the element head of the radial piston according to the invention.
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings. The features mentioned in the claim and in the description can be essential to the invention by themselves or in arbitrary combinations.
REFERENCES:
patent: 3779225 (1973-12-01), Watson et al.
patent: 4140440 (1979-02-01), Ferris
patent: 4395990 (1983-08-01), Hofer et al.
patent: 4489698 (1984-12-01), Hofer et al.
patent: 5382140 (1995-01-01), Eisenbacher et al.
patent: 5820358 (1998-10-01), Kushida et al.
patent: 5979297 (1999-11-01), Ricco
patent: 6139284 (2000-10-01), Streicher
Simon Hans-Juergen
Streicher Bernd
Freay Charles G.
Gartenberg Ehud
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
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