Rotary expansible chamber devices – Self-acting unidirectional flow with reverse rotation or...
Patent
1985-01-21
1986-05-13
Vrablik, John J.
Rotary expansible chamber devices
Self-acting unidirectional flow with reverse rotation or...
418171, F04C 210, F04C 1502
Patent
active
045883629
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a reversible unidirectional flow gerotor pump. Such pumps are used in apparatus where unidirectional pump output is required even if the direction of rotation of the pump is reversed. One example of such a pump is disclosed in our British prior Pat. No. 2,029,905.
Such pumps generally employ a rotatable reversing ring which, in response to reversal of the direction of rotation of the pump, may automatically allow the rotational axis of the pump annulus to orbit through an angle of 180.degree. about the axis of the inner rotor so as to reposition the annulus and thereby maintain unidirectional flow.
One drawback with such pumps results from the need to positively couple the annulus and reversing ring together during such reversals so that the annulus can rotate the reversing ring between diametrically opposite stop positions. Friction alone has not proved entirely satisfactory in practice and this has led to the use of spring loaded couplings between the annulus and the reversing ring as in British Pat. No. 2,029,905 for instance. Experience shows however that such couplings are not wholly satisfactory because they can give rise to problems with wear and they are, in any event, more cumbersome to manufacture and assemble.
According to the present invention we provide a reversible unidirectional flow gerotor pump comprising an inner toothed rotor and an internally toothed annulus which meshes with the inner rotor and rotates about an axis which is eccentrically related to the rotor axis, the annulus being rotatable in a reversing carrier ring located in a pump body, and the axis of the annulus being movable between a pair of operative positions in one of which liquid is pumped in a predetermined direction during rotation of the rotor and annulus in one direction and in the second of which liquid is pumped in the same direction during rotation of the rotor and annulus in the opposite direction, characterised in that the reversing carrier ring is supported in the pump body to pivot between positions providing two seating positions for the annulus corresponding respectively to said pair of operative positions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a gerotor pump in accordance with the invention, the pump being shown in its normal operative condition with the rotor and annulus rotating clockwise;
FIG. 2 is a view similar to FIG. 1 but showing the initial stages of transfer of the annulus from one position to another as a result of rotation reversal.
The pump in FIG. 1 comprises an inner toothed rotor 10, an annulus 12 having one extra tooth, a carrier 14 which supports the annulus 12 and an outer housing 15. The axis 16 of the rotor is fixed and is substantially co-axial with an input drive shaft (not shown) coupled to the inner rotor. The axis 18 of the annulus is eccentrically related to the axis 16 and in the condition shown in FIG. 1 the axis 18 is effectively fixed as long as the rotor and annulus rotate clockwise.
The inner periphery of the carrier 14 comprises a lower portion centred on a centre of curvature which substantially coincides with the axis 18 when the annulus is seated within the lower half of the carrier. The upper part of the carrier is centred on a centre of curvature which is vertically offset from that of the lower half and the two halves are joined by planar intermediate sections 25 so that the bore of the carrier is slightly elongated in a vertical direction to afford the annulus a certain degree of radial freedom in that direction relative to the axis 16. This radial freedom is of no significance in normal clockwise rotation of the annulus since the annulus bears (substantially frictionlessly because of hydrodynamic pressure) against the lower half 22 of the carrier. The pump creates a unidirectional liquid flow from inlet port 21 to outlet port 23.
The carrier 20 is movable about a fulcrum 24 between a first slightly tilted position as seen in FIG. 1 and a second position in substantially mirror image relation to that of FIG. 1 wh
REFERENCES:
patent: 2373368 (1945-04-01), Witchger
patent: 3034447 (1962-05-01), Brundage
patent: 3583839 (1971-06-01), Brundage
Concentric Pumps Limited
Marshall, Jr. C. O.
Vrablik John J.
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