Pumps – Successive stages
Patent
1999-05-28
2000-10-03
Walberg, Teresa
Pumps
Successive stages
417273, 123198DB, 123299, H05B 100, H05B 302
Patent
active
061264075
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention relates to a pump device for high pressure fuel delivery in fuel injection systems of internal combustion engines, in particular in a common rail injection system, including a radial piston pump with a drive shaft that is supported in a pump housing and is embodied eccentrically or has cam-like projections in the circumference direction. Preferably a number of pistons are disposed in a cylinder chamber radially in relation to the drive shaft and can be driven to reciprocate in the cylinder chamber when the drive shaft rotates, and includes a check valve on the intake side and the high pressure side, and a low pressure pump connected before the radial piston pump.
The supply of fuel to the radial piston pump, which produces the high pressure takes place in a known manner by means of a low pressure pump as the pre-feed pump.
In known pump devices, the low pressure pump is disposed spatially separate from the radial piston pump. The low pressure pump is usually embodied as a separate pump and is driven by a shaft of the internal combustion engine or it is embodied as an electric pump.
In order to accommodate two pumps that are spatially separate from each other, a corresponding space is required, and additional fastening points must be produced for the pump housing. In addition, it requires additional fuel lines in order to connect the low pressure pump to the radial piston pump. As a result, there is an increased danger that leaks will occur.
Based on this, the object of the current invention is to produce a pump device of the type described at the beginning in which the above-explained disadvantages do not occur. In particular, a compact pump device should be produced that saves space and is inexpensive to produce.
This object is attained according to the invention by means of a pump device of the type mentioned at the beginning by virtue of the fact that the low pressure pump on or in the pump housing of the radial piston pump is provided on the end remote from the drive end and can be driven by the drive shaft of the radial piston pump.
This reduces the number and length of the fuel-carrying lines outside the pump housing and thus reduces the danger that external leaks will occur. Furthermore, a very compact construction of the pump device can be achieved. Because of the savings in housing parts and the realization of a common drive train, the pump can also be produced more cheaply.
In a preferred manner, a coupling is interposed between the drive shaft of the radial piston pump and a shaft of the low pressure pump. As a result, assembly or manufacture precision of the components of the radial piston pump and the low pressure pump, in particular flush deviations of the drive shaft of the radial piston pump and the shaft or of a corresponding shoulder in the low pressure pump can be compensated for.
The use of an Oldham coupling has turned out to be suitable, particularly in the embodiment of the low pressure pump as a gear pump that is relatively flat in structure.
In a particularly preferred manner, the housing of the low pressure pump is embodied as essentially disk-shaped, which is why a gear pump has turned out to be particularly suitable.
The housing of the low pressure pump preferably can be mounted to the pump housing of the radial piston pump by way of a centering means. To this end, it turns out to be advantageous if a centering flange that protrudes in the direction of the housing of the low pressure pump is provided on the pump housing of the radial piston pump, with which flange the housing of the low pressure pump can be positioned. It goes without saying that a converse embodiment of the centering flange on the housing of the low pressure pump is also included in this concept of the invention.
In order to seal the low pressure pump and the radial piston pump in relation to the outside, it has turned out to be sufficient and advantageous to provide an elastomer sealing means that is advantageously disposed between the centering flange of the radial piston pump and the
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Guentert Josef
Hammer Juergen
Kuhn Uwe
Lettner Thomas
Streicher Bernd
Fastovsky Leonid
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Walberg Teresa
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