Rotary expansible chamber devices – Positively actuated vane – Cam actuated
Patent
1998-10-13
2000-07-11
Nguyen, Hoang
Rotary expansible chamber devices
Positively actuated vane
Cam actuated
418265, 418266, F01C 100
Patent
active
06086348&
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a fuel injection pump as generically defined hereinafter. One such fuel injection pump is known from German Patent Application DE-A1 30 12 983. The toothing provided there on the circumference of the drive shaft has a substantially lesser height than the axial height of the inner ring. Feed pumps of this kind, also known from German Patent Application DE-A 28 49 012, having an inner ring and an outer ring, which are eccentric to one another with adjacent outer faces, so that there is an intermediate chamber between the wheels that comes continuously larger and then shrinks again. The intermediate chamber is subdivided by vanes, which are placed in radial slots of the inner ring and move radially outward under the influence of centrifugal forces or restoring forces and come to rest on the inner wall of the outer ring, thereby dividing the intermediate chamber into individual cell chambers. Via these cell chambers, the fuel is first aspirated and then delivered, compressed, to an outlet side as the shrinkage in the radial width between the outer and inner walls of the aforementioned wheels increases. The inner wheels of the pump are connected to the drive shaft either by toothing in accordance with DE-A 30 12 983 or by a spline and groove connection in accordance with DE-A 28 49 012. The spline and groove connection can also be understood as a set of teeth over a portion of the circumference. While in the latter of these embodiments the space required for the coupling between the inner ring and the drive shaft is very great, in the first of these embodiments, conversely, because of the toothing all the way around, the space required is substantially less for the same force transfer. Variable clearance tolerances, which because of the requisite tightness are especially low in the region of the feed pump but conversely can be greater in the region of the drive shaft and its coupling to the inner ring, mean that in the known embodiment high edge pressures can occur in the region of the toothing, because of angular deviations between the plane in which the inner ring of the feed pump is guided and the radial plane of the drive shaft through which the axis of the drive shaft passes at a right angle. This has the disadvantage of heavy wear and requires a high driving power.
ADVANTAGES OF THE INVENTION
By means of the fuel injection pump of the invention, it is attained that edge pressures are essentially avoided, and large load-bearing faces on the individual teeth of the sets of teeth are assured. The wear and the tendency to seizing between the inner ring and the toothing of the drive shaft and/or between the inner ring and the adjacent pump housing parts are reduced. Since the inner ring is now no longer exposed to tilting motions from, the drive side, the very close guidance of the inner ring that is essentially free of tilting forces, which can cause damage here, also follows. Because of the low friction, there is little wear, and it becomes possible to transmit higher torques for the same pumping capacity. The width of the toothing can be increased compared with the known embodiment, since because of the tooth design, even with wider teeth, tilting moments are no longer transmitted to the inner ring of the feed pump.
BRIEF DESCRIPTION OF THE DRAWING
An exemplary embodiment is shown in the drawing and will be described in further detail in the ensuing description.
FIG. 1 is a section through a fuel injection pump of the distributor type in the region of the feed pump;
FIG. 2 is a section through the distributor pump of FIG. 2 taken along the line II--II; and
FIG. 3 shows a drive tooth as an enlarged detail, of the toothing on the drive shaft of the invention.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
Fuel injection pumps of the distributor pump type typically have a feed pump integrated into the housing of the fuel injection pump. They may be embodied as a so-called reciprocating piston distributor pump, of the kind known from the prior art DE-A1 30 12 983 cited at
REFERENCES:
patent: 2832199 (1958-04-01), Adams et al.
patent: 2910976 (1959-11-01), Fancher
patent: 3113527 (1963-12-01), Kramer
patent: 3138112 (1964-06-01), Porta et al.
patent: 3785758 (1974-01-01), Adams et al.
patent: 4041921 (1977-08-01), Eckert et al.
patent: 5588821 (1996-12-01), Kinoshita
patent: 5899677 (1999-05-01), Ono et al.
Fehlmann Wolfgang
Nothdurft Heinz
Senghaas Clemens
Greigg Edwin E.
Greigg Ronald E.
Nguyen Hoang
Robert & Bosch GmbH
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