The present invention relates to a pump, in particular to a vane-type pump, roller-cell pump, or gear pump, having a rotary assembly, which includes, inter alia, a rotor having radially displaceable vanes or rollers, or gear wheels, and having a drive shaft, the drive shaft and the rotor, respectively a gear wheel, being interlinked by a toothing on the drive shaft and on the rotor, respectively on the gear wheel, for purposes of rotational entrainment.
Pumps of this kind are generally known. In this context, the pumps have toothed-shaft connections having involute flanks according to DIN 5480 or spline-shaft connections having straight flanks according to DIN 5463. Neither type of connection exhibits axial convexity on the toothing, so that it is not possible to compensate for any skewed position among the drive partners. Moreover, due to the minimal clearance between the tooth flanks, torsional shocks from the drive shaft are transmitted, undamped, to the drive partners, thereby promoting wear on the drive partners.
It is, therefore, the object of the present invention to devise a pump which will overcome these disadvantages.
This objective is achieved by a pump, in particular a vane-type pump, roller-cell pump, or gear pump, having a rotary assembly, which includes, inter alia, a rotor having radially displaceable vanes or rollers, or gear wheels, and having a drive shaft, the drive shaft and the rotor, respectively a gear wheel, being interlinked by a toothing on the drive shaft and on the rotor, for purposes of rotational entrainment, the toothing being designed in accordance with the present invention to be axially convex and radially externally centered.
The external centering has the advantage of making it possible to brace against transversal forces. In the case of two-stroke vane pumps, the external centering provides for a better centering.
A pump is preferred in which the toothing, in addition, exhibits a circumferential clearance among the tooth flanks. It is a distinguishing feature of a pump according to the present invention that the circumferential clearance encompasses an angular region of 3° to 12°, preferably of 6°.
A pump is also preferred in which the toothing, in addition, is able to be acted upon by a transversal force.
It is a distinguishing feature of a pump according to the present invention that the transversal force acting on the external centering surfaces produces tangential frictional forces between the drive shaft and the rotor, and respectively the gear wheel. This has the advantage of enabling torsional shocks to be damped, due to the circumferential clearance and the frictional forces. A pump is also preferred in which the tooth flanks of the toothing have the form of an involute toothing. A pump is also preferred in which the flanks may have a convex design in the axial direction.
It is a distinguishing feature of a pump according to the present invention that the teeth of the shaft are designed to be wider than the teeth of the rotor or of the gear wheel. As a result, the teeth of the shaft, which are required to absorb the transversal force and produce the moment of friction, are advantageously able to have high enough strength for this purpose. A pump is also preferred in which the teeth of the shaft are more than twice as wide as the teeth of the rotor or of the gear wheel.
The pump is now described with reference to the figures, which show:
A rotor 1 of a six-vane vane pump having an internal toothing according to the present invention is shown in
In
In
Another feature of the toothing according to the present invention is that, between teeth 7 of the rotor and teeth 19 of the shaft, a clearance 49 results, which may include an angular region of 3° to 12°, preferably of 6°. The advantage of this clearance is that, when working with minor torsional shocks of the shaft within this clearance region, the torsional shocks are not transmitted to the rotor in a manner that produces positive engagement. The frictional forces occurring between outside diameter 23 of shaft toothing 19 and inside diameter 11 of rotor toothing 7 act in this context as damping forces between the two motions of the rotor and shaft.
The approach in accordance with the present invention with regard to this toothing thus provides for combining the advantages of an outside diameter-centered spline shaft connection, of a toothed-shaft connection including involute flanks, of axial convexity of the toothing for preventing angular errors between the rotor and shaft, and of an increased clearance among the tooth flanks. The present invention is especially useful for those pumps which are subject to torsional vibrations due to their mounting location, such as diesel presupply pumps, where the diesel motor produces such vibrations at the drive shaft. The axial convexity of the toothing compensates for any possible skewed position of the rotor relative to the drive shaft which is secured, for example, to a camshaft of the combustion engine. The outside-diameter centering of the toothing on the shaft braces against the transversal forces during operation. This prevents a relative motion of the drive partners along the toothing flanks and thus reduces the wear that the toothing is subject to compared to a conventional toothing. At the same time, the friction present at the outside-diameter centering of the toothing of the drive partners is used for damping of the torsional vibrations. The increased clearance among the tooth flanks permits rotation of the drive partners relative to one another, as well as damping of the effects of the torsional vibrations, due to the friction present at the outside-diameter centering. As a result, contact shocks at the tooth flanks are minimized or eliminated due to torsional vibrations, thereby minimizing wear.
The present invention may be used analogously for other pumps as well, such as for gear pumps, for example, where the torque entrainment between the drive shaft and the gear wheel driven by the shaft is also subject to the action of corresponding transversal forces. However, this toothing is likewise advantageous for pumps that are not subject to transversal forces, such as two-stroke vane pumps, since the outside-diameter centering of the shaft toothing and the inside-diameter centering of the rotor provide for a better centering of the shaft than do known toothings. In this case as well, any possible skewed position of the rotor relative to the shaft is able to be compensated by the axial convexity of this toothing according to the present invention.
Number | Date | Country | Kind |
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10 2004 022 670.9 | May 2004 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/DE2005/00800 | 4/30/2005 | WO | 00 | 11/6/2006 |