Permeable mesh current collector for DC machines

Claim 2

An electrical current collector for an electrical machine having a stator and a rotor, said rotor being rotatable relative to said stator about an axis thereof, comprising: a rotor collector ring; a stator collector ring encircling said rotor collector ring; brush means affixed to said stator collector ring contiguous with the radially-inner surface thereof; said brush means comprising at least one layer of porous, compliant, electrically conductive, liquid metal-permeable material, disposed in face-to-face contact with said radially-inner surface of said stator collector ring and extending radially-inward to a location closely adjacent said rotor collector ring, and spaced therefrom by a narrow annular gap; and liquid metal supply means in flow communication with said brush means for supplying liquid metal thereto; said liquid metal filling the interstices of said porous, liquid metal-permeable material and flowing therethrough to fill said gap between said brush means and said rotor collector ring, thereby establishing electrical contact between said rotor collector ring and said brush means.

Claim 3

The apparatus of claim 1 wherein: said brush means comprises a plurality of layers of porous, compliant, electrically conductive, liquid metal-permeable material secured to said stator collector ring by a holder affixed to said stator collector ring; and said holder comprises first and second nonporous, conductive brush holding members said first brush holding member being affixed to one axial side of said stator collector ring, and said second brush holding member being affixed to the opposite axial side of said stator collector ring, said brush holding members projecting radially-inward beyond the radially-inner surface of said stator collector ring to form a circumferential channel for holding said brush contiguous with said surface.

Claim 4

The apparatus of claim 2 wherein said liquid metal-permeable material comprises a mesh of conductive filaments.

Claim 5

The apparatus of claim 3 wherein the filaments comprise copper wires plaited into braid.

Claim 6

The apparatus of claim 4 wherein said brush means further comprises a pair of solid, flexible baffle means of conductive material located between alternate pairs of said layers, and axially adjacent said first and second brush holding members, respectively, to form an open passage through the axially central portion of said brush means to direct flow of liquid metal through said open passage; and wherein said liquid metal comprises a sodium-potassium eutectic alloy.

Claim 7

The apparatus of claim 5 further comprising non-conductive liquid metal containment means attached to the axially-outer surface of each of said first and second brush holding members, respectively, for confining said liquid metal within a region surrounding the radially-outer surface of said rotor collector ring.

Claim 8

The apparatus of claim 6 wherein said containment means comprise flexible, insulating strips having one end thereof biased against an axial surface of said rotor collector ring.

Claim 9

The apparatus of claim 1 wherein: said brush means comprises a plurality of layers of porous, compliant, electrically conductive, liquid metal-permeable material secured to said stator collector ring by a holder affixed to said stator collector ring; and said holder comprises first and second nonporous, conductive brush holding members, said first brush holding members being affixed to the radially-inner surface of said stator collector ring at one axially outermost portion of said surface, and said second brush holding member being affixed to the radially-inner surface of said stator collector ring at the other axially outermost portion of said surface, said brush holding members projecting radially-inward from said surface and forming a circumferential channel for holding said brush contiguous with said surface.

Claim 10

The apparatus of claim 8 wherein: said liquid metal-permeable material comprises a mesh of fine copper wires plaited into braid; and said brush further comprises a pair of solid, flexible baffle means of conductive material located between said alternate pairs of layers and axially adjacent said first and second brush holding members, respectively, to form an open passage through the axially central portion of said brush means and to direct a flow of liquid metal through said open passage; and wherein said liquid metal comprises a sodium-potassium eutectic alloy.

Claim 11

An electrical machine having a stator and a rotor, said rotor being rotatable relative to said stator about an axis thereof, and having a plurality of electrical current collectors for making electrical contact between said stator and said rotor, said current collectors comprising: a plurality of axially spaced rotor collector rings; a plurality of stator collector rings encircling said rotor collector rings, respectively; a plurality of brush means attached, respectively, to each of said stator collector rings contiguous with the radially-inner surface thereof; each of said brush means comprising at least one layer of porous, compliant, electrically conductive, liquid metal-permeable material disposed in face-to-face contact with said radially-inner surface of one of said stator collector rings, respectively, and extending radially-inward to a location closely adjacent a respective one of said rotor collector rings and spaced therefrom by a narrow annular gap; and liquid metal supply means in flow communication with said plurality of brush means to continuously supply liquid metal thereto; said liquid metal filling the interstices of each of said brush means and flowing therethrough to fill each said gap thereby establishing electrical contact between each said rotor collector ring and each said brush means, respectively.

Claim 12

An electrical machine having a stator and a rotor, said rotor being rotatable relative to said stator about an axis thereof, and having a plurality of electrical current collectors for making electrical contact between said stator and said rotor, said current collectors comprising: a plurality of axially spaced rotor collector rings; a plurality of stator collector rings encircling said rotor collector rings, respectively; a plurality of brush means attached, respectively, to each of said stator collector rings contiguous with the radially-inner surface thereof; each of said brush means comprising at least one layer of porous, compliant, electrically conductive, liquid metal-permeable material disposed in face-to-face contact with said radially-inner surface of one of said stator collector rings, respectively, and extending radially-inward to a location closely adjacent a respective one of said rotor collector rings and spaced therefrom by a narrow annular gap; and liquid metal supply means in flow communication with said plurality of brush means to continuously supply liquid metal thereto; said liquid metal filling the interstices of each of said brush means and flowing therethrough to fill each said gap thereby establishing electrical contact between each said rotor collector ring and each said brush means, respectively.

Claim 13

The apparatus of claim 10 wherein the radially-innermost surface of each respective stator collector ring is parallel to the radially-outermost surface of the rotor collector ring encircled thereby, respectively, and said surface of said stator collector ring and said surface of said rotor collector being generally parallel to the direction of flux lines produced by an excitation coil located within said rotor which pass through the narrow gap located between said surfaces.

Claim 14

The apparatus of claim 11 wherein said liquid metal supply means includes pumping means in flow communication with inlet passages in each of said stator collector rings to provide a pressurized flow of liquid metal to each of said brush means.

Claim 15

The apparatus of claim 12 wherein said liquid metal comprises a sodium-potassium eutectic alloy.

Claim 16

The apparatus of claim 13 wherein each said brush means is affixed to said respective stator collector ring by a brush holder so that each of said layers of said brush means is held generally parallel to said radially-innermost surface of said respective stator collector ring; and each said holder comprises first and second nonporous, conductive brush holding members, said first brush holding member being affixed to one axial side of said stator collector ring, and said second brush holding member being affixed to the opposite axial side of said stator collector ring, said brush holding members projecting radially-inward beyond the radially-innermost surface of said stator collector ring to form a circumferential channel for holding said brush contiguous with said radially-innermost surface.

Claim 17

The apparatus of claim 14 wherein each said brush means comprises a plurality of stacked layers of fine copper wires plaited into a braid.

Claim 18

The apparatus of claim 14 wherein each said brush means comprises a plurality of stacked layers of fine copper wires coated with a material selected from the group consisting of gold, silver, tin and nickel, said wires being plaited into a braid.

Claim 19

The apparatus of claim 14 wherein each said brush means comprises a plurality of stacked layers of fine wires of metallurgically-bonded, copper-coated steel wires plaited into a braid.