Rotary expansible chamber devices – Moving cylinder – Rotating
Patent
1997-04-30
1999-04-06
Vrablik, John J.
Rotary expansible chamber devices
Moving cylinder
Rotating
F04C 210
Patent
active
058908854
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a filling member-less internal-gear pump having an improved design configuration for the internal-gear pump, which results in better sealing of the intermeshing teeth.
Filling member-less internal-gear pumps and motors have a tooth arrangement comprising a pinion and an annular gear, the teeth of which are sealingly in mutual contact both at the mutual engagement in gaps between the teeth and also, in approximately diametrally opposite relationship, at the oppositely disposed tooth tips, in order thereby to delimit the suction region from the pressure region. Tooth arrangements on a trochoid and a cycloid basis, but also tooth arrangements of other kinds, are considered for that purpose. As however in practice because of inevitable tolerances and because of the deformations which occur in particular at comparatively high pressures it is not possible to achieve the above-mentioned sealing contact, in particular in the region of the tooth arrangements in which the tooth tips are to bear against each other, steps must be taken to ensure such sealing contact.
In a known internal-gear pump of the above-described kind (DE-C-44 21 255) the annular gear is accommodated in a running ring, forming an annular gap therewith, and it is mounted in the casing by way of the ring. Sealing elements are radially movably accommodated in axial grooves in the peripheral surface of the annular gear, the sealing elements dividing the annular gap between the running ring and the peripheral surface of the annular gear into peripheral portions which can be sealed off relative to each other. By way of a groove provided in the casing in the region of the pressure chamber, that configuration ensures that, when the corresponding peripheral portions pass into the pressure chamber, pressure fluid is fed thereto. In that way, a pressure which is directed towards the suction chamber side is built up in the peripheral portions which are in the pressure chamber, and that force causes the tips of the teeth of the pinion and the annular gear to come to bear sealingly against each other.
As the annular gear is not mounted in the casing directly but by way of the running ring, with the formation of an annular gap therebetween, a radial force on the annular gear can be produced as between the running ring and the peripheral surface of the annular gear, in the pressure region, by virtue of the action of pressure fluid. The magnitude of that radial force can be structurally determined by the length of the groove carrying the pressure fluid and by the size and number of the peripheral portions into which the annular gap is divided. As the running ring rotates together with the annular gear, that is to say its entire outside periphery forms the bearing surface, only a small amount of wear occurs, while only very slight relative movements and therewith also no wear worth mentioning occur as between the sealing elements and the inside periphery of the running ring.
The groove which carries the pressure fluid and through which pressure fluid is fed to the annular gap when the corresponding peripheral portions pass into the region of the groove is of a part-circular configuration and at its end overlaps with the annular gap, whereby the pressure fluid can flow into same in the axial direction. On the side opposite that groove, the pump may have a discharge or relief groove of similar configuration, which is connected to the suction chamber and through which, in the peripheral portions which reach the relief groove, the annular gap is relieved again of the load of the pressure obtaining in the peripheral portions. That configuration guarantees force relationships which are precisely defined in each case by the pressure difference between the suction and the pressure sides of the internal-gear pump.
As a result of the annular gap, in operation the annular gear adopts a position which is determined solely on the basis of the equilibrium of the pressures obtaining in the tooth arrangement and in the annular gap. For that reason mechanic
REFERENCES:
patent: 3680989 (1972-08-01), Brundage
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