Rotary expansible chamber devices – Interengaging rotating members – Multiple units
Patent
1994-07-20
1996-03-05
Vrablik, John J.
Rotary expansible chamber devices
Interengaging rotating members
Multiple units
418206, 74421R, F01C 118, F01C 1100, F04C 218, F04C 1100
Patent
active
054961637
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates generally to a gear machine. In a prior gear machine known from DE-OS 27 05 249, the two toothed wheels arranged on a drive shaft are attached to the drive shaft by a gearing or toothing extending over the entire width of these toothed wheels. A disadvantage in this known gear machine consists in that axial forces passing into the drive shaft, e.g., such as those axial forces occurring in a gear machine driven via a helical-geared drive shaft, are transmitted to a front bearing via the relatively small end face of the toothing. The resulting high surface-area pressure causes a high degree of wear in this bearing. Further, for advantageous support of the toothed wheels on the drive shaft, the known gear machine requires a toothing with little radial clearance or play which raises the cost for manufacturing the toothing. The use of toothing with radial play causes an increase in the amount of chips occurring during the breaking-in period of the gear machine. Moreover, radial play in the toothing results in poor efficiency in the known gear machine owing to increased wear and friction work between the internal toothing of the toothed wheels and the external toothing of the drive shaft.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a gear machine of the above mentioned general type, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a gear machine in which the toothing width of the driven toothed wheels is smaller than their toothed wheel width, the driven toothed wheels contact the end faces of the toothing in a positive locking manner via shoulders, the driven toothed wheels are arranged on the drive shaft so as to be free of radial play, the width of said additional toothing of said driven toothed wheel being smaller than one-half of said width of said external toothing, said driven toothed wheels being slidingly supported on said shaft and abutting against said drive shaft over a whole width of said driven toothed wheel which width is not covered by said external toothing.
When the gear machine is designed in accordance with the present invention, it has the advantage over the prior art that axial forces passing into the drive shaft are transmitted to the front bearing of the drive shaft along the entire end face of a driven toothed wheel. This reduces wear on this bearing. Further, it is particularly advantageous that the driven toothed wheels are guided on the drive shaft in the radial direction by a portion of their width so as to enable a simple connection without radial play with corresponding dimensional tolerances between the toothed wheel and drive shaft. This reduces wear in the toothing. Since the toothing serves only to transmit the driving torque to the toothed wheels, it is possible to use tooth shapes which can be produced inexpensively.
Also, when the gear machine is designed in accordance with the present invention, the hydraulic forces occurring in operation are transmitted by the toothed wheels to the drive shaft in such a way that no tilting moments occur, thus improving the operation of the gear machine.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a longitudinal section through a dual-gear pump;
FIG. 2 shows a cross section in direction II--II according to FIG. 1;
FIG. 3 shows another cross section through a drive shaft and toothed wheels in direction III--III according to FIG. 1;
FIG. 4 shows a longitudinal section through a gear
REFERENCES:
patent: 1014150 (1912-01-01), Herrick
patent: 4293290 (1981-10-01), Swanson
patent: 4699575 (1987-10-01), Geisel et al.
patent: 4728271 (1988-03-01), Harwath
Bredenfeld Guido
Griese Klaus
Hesse Horst
Robert & Bosch GmbH
Striker Michael J.
Vrablik John J.
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