Pumps – Motor driven – Including means for facilitating assembly or disassembly of...
Reexamination Certificate
1998-11-25
2001-04-03
Thorpe, Timothy S. (Department: 3746)
Pumps
Motor driven
Including means for facilitating assembly or disassembly of...
C417S364000, C464S901000
Reexamination Certificate
active
06210129
ABSTRACT:
The invention relates to a pump, in particular a high-pressure pump for a fuel injection device of an internal combustion engine;
PRIOR ART
DE 44 19 927 A1 has disclosed a high-pressure pump for fuel embodied as a piston pump, and a piston/cylinder unit, which contains a work chamber, disposed in the pump housing of this high-pressure pump, and a pump shaft for driving the piston/cylinder unit is supported in this pump housing. The pump shaft is supported in its center and, on its cantilevered drive-side end, supports a cam which is used to act on the piston/cylinder unit. In order to drive the pump shaft, a drive gear is fastened to its end protruding from the pump housing.
The support of the pump shaft in the pump housing results in a relatively large structural length of the pump, which consequently has a relatively large space requirement. In addition, a relatively costly drive connection from a motor shaft to the drive gear is required, which likewise requires a certain amount of installation space in the engine compartment. Furthermore, large bearing loads are produced, which lead to an increased wear and to a reduced service life since the effective bearing length is relatively small compared to the length of the drive-side end of the pump shaft protruding from the bearing.
DE 42 17 910 A1 has disclosed a hydraulic pump driven by an internal combustion engine, which is disposed in a cavity in a cylinder head wall. An end of a cam shaft, on which a cam is non-rotatably disposed, which drives a piston of a pump element, extends into this cavity through an opening in the cylinder head wall. After the insertion of the pump element and the attachment of the cam to the cam shaft end, the cavity in the cylinder head wall is closed by means of a cap.
This known pump, which is used as a lubricant pump, does indeed have a relatively short structural length, but cannot be produced independently of the internal combustion engine. Furthermore, the function of this known pump and of its individual pump elements can only be tested after installation into the cylinder head wall of the engine.
ADVANTAGES OF THE INVENTION
The pump according to the invention, has the advantage over the prior art that through the non-rotatable support of the pump shaft on a shaft of the drive motor, no bearings are needed for the pump shaft in the pump housing so that a shortened structural length of the pump is produced. Moreover, the elimination of the bearing of the pump shaft in the pump housing results in an increased service life.
Furthermore, the pump according to the invention can be manufactured as a separate subassembly and can be tested as to its function independently of the internal combustion engine. In transport and storage, in order to prevent uncontrolled movements of the movable pump elements and therefore to prevent damage and problems in the subsequent installation, in a preferred exemplary embodiment of the invention, a transport securing device is provided for the pump shaft, which preferably has two securing means spaced apart from each other.
It is particularly advantageous if the passage of the pump shaft out of the pump housing is sealed since the pump interior is thus protected from impurities during storage, transport, and installation.
In order to be able to compensate for a radial play in the bearing of the shaft of the internal combustion engine without influencing the tightness of the pump, in an advantageous embodiment of the invention, the provision is made that the passage of the pump shaft out of the pump housing is sealed by means of an axial shaft seal in which two smooth faces are pressed tightly against each other. As a result, a perfect seal can be assured, even with an eccentric motion of the sealing faces in relation to each other.
A particularly non-problematic installation of the pump is produced if the pump shaft has a drive-side bearing pin which can be slid into a corresponding axial bore in the shaft of the internal combustion engine. This embodiment also permits the particularly simple connection of an auxiliary drive, which is necessary for a test operation of the pump for testing purposes.
Advantageous improvements and updates of the piston pump disclosed are possible by means of the measures taken hereinafter.
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Gray Michael K.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Thorpe Timothy S.
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