US 4,405,286 AGranted

Actively suspended counter-rotating machine

AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration

InventorPhilip A. Studer

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Abstract

A counter-rotating machine, such as a positive displacement pump having a pair of meshed, non-contacting helical screws (10,12), subjects its rotating members to axial and radial thrust forces when used for such purposes as compression of liquid or gaseous phase fluids while transporting them through a pump cavity (11,13). Each helical screw (10,12) has a shaft (17,17') which is actively suspended at opposite ends (11a,11b) of the pump cavity by a servo-controlled magnetic bearing assembly (19) and a servo-controlled rotary drive motor (20). Both bearing assemblies and drive motors are mounted on the outside of the pump cavity (11,13). Opto-electric angular position sensors (250) provide synchronization between radial orientation of the drive motors. The bearing assemblies and drive motors conjugately provide axial stabilization and radial centering of the helical screws during volumetric compression of aspirated liquid or gaseous phase fluids.

Claims15

Dependent claims

An actively suspended counter-rotating machine, comprising:

a plurality of shafts (17,17');
an equal plurality of means (10,12) mounted on said shafts in close, non-contacting fit for subjecting intermediate substances to axial and radial compression during counter-rotation of said shafts;
an equal plurality of means (19,19') coaxially disposed around one end of said shafts for generating in adjoining sectional lengths (17a, 17c) of said shafts a first plurality of opposed, magnetic flux paths (22, 24) radially penetrating and axially traversing said sectional lengths;
a plurality of means (211-214, 216-219) symmetrically arrayed around the other end of said shafts for radiating a second plurality of opposed magnetic flux paths (22/24) each traversing central magnetic flux path segments lying within planes passing along the longitudinal axes (18,18') through said shafts;
an equal plurality of means (237, 238) each coaxially disposed in proximity to said radiating means around said shaft ends for each creating torque about longitudinal axes when energized by electrical currents flowing orthogonally to said central magnetic flux path segments;
an equal plurality of discrete means (248, 248') affixed to said different shafts ends in conjugate proximity to said central magnetic flux path for converting said torque into counter-rotation of said shafts;
and
means (250) responsive to the angular rotation of said shafts for synchronizing the energization of said plurality of torque creating means (237,238).

5 more elements

A rotary positive displacement pump comprising:

a pair of non-contacting, meshed helical screws (10,12) each having a shaft (17,17') extending from opposite bases;
a pump casing (14) having inlet (15) and discharge (16) ports forming a close, non-contacting fit around said meshed helical screws (10,12);
a pair of magnetic bearing assemblies (19,19') external to said casing supporting different ones of said shafts, each of said magnetic bearing assemblies comprising:
a plurality of permanent magnets (32,36) aligned in an axially symmetric array separated from a first section (17a) of a shaft extending from one of said bases,
a plurality of magnetically soft and pieces (46,50) arranged in axially separated pairs adjoining opposite ends (38,40) of said permanent magnets (32) and forming a plurality of axially separated and axially symmetric arrays to define a gap (56) between said end pieces and said first shaft section (17a) thereby providing a first magnetic flux path (22) passing between said axially separated arrays via said first shaft section (17a) and
coil means (26) defining a second magnetic flux path (28) passing through a section of said shaft (17b) adjoining said first shaft section (17a) for selectively modulating magnetic flux flowing in adjoining flux paths (22) within said shaft (17,17');
a pair of drive motors (20,20') external to said casing (14) supporting the ends of individual ones of said shafts opposite said magnetic bearing assemblies (19,19'), each of said motors comprising:
a plurality of separate field windings (211-214);
an armature winding (238);
means (84) for providing current flow in said field windings;
means for providing current flow in said armature winding (238);
and
a rotor (235, 243, 244, 248) connected to one of said opposite shaft ends, for coupling flux derived from said field windings (211-214) in an interacting relation with current flowing in said armature winding (238) whereby said rotor is driven relative to said field windings in response to said interaction;
means (288) for sensing the position of said rotor relative to said field windings (211-214);
and means (82,84) responsive to said sensing means for controlling the relative amplitudes of current flowing in said field windings (211-214) to maintain said rotor in a predetermined position relative to said field windings;
and
means (250) for synchronizing said current flow between each said armature (238) winding in said pair of drive motors (20) whereby said helical screws are held in a meshed, non-contacting relation.

14 more elements

Dependencies are inferred from the claim text.