Abstract: A collector for an electric motor or generator with lamellae, which are distributed symmetrically to a collector axis at the periphery or at a front face and which are embedded in a basic body of insulating material, the collector having a central opening, which is designed with respect to its diameter for a press fit on the shaft of the electric motor or generator and is reinforced by a bushing element of higher strength for absorbing the seating and pressing-on forces, is designed in the sense of being easier and less expensive to manufacture, being handled more readily and less critically while being pressed onto the shaft of a motor and being more robust and having a longer service life, so that the busing element has an internal diameter, which is larger than the diameter of the opening, and that the bushing element is covered on the inside by a layer of insulating material.

Abstract: An electrical machine which has a rotor positioned within a housing. The rotor has a pair of spaced-apart engagement portions, which, preferably, are tapered. The engagement portions are engaged by collectors or brushes which are arranged in annular configuration around the engagement portions. Retainer support the collectors and serve as electrical conductors with respect to the collectors. Wick elements engage the tapered portions of the rotor adjacent the collectors and provide lubrication and coolant fluid to the collectors and to the surfaces of the engagement portions of the rotor. Actuator mechanisms continuously urge the retainer members and the collectors in an axial direction upon the engagement portions to automatically compensate for wearing action between the collectors and the engagement portions of the rotor. A stator encompasses the rotor to create a magnetic field which encompasses the rotor.

Abstract: A superconducting DC machine includes a superconductive field winding housed in a cryostat. A magnetic shield is arranged outside the cryostat. An armature drum is rotatably supported between the cryostat and the magnetic shield. The armature drum of the machine is divided into a plurality of segments along the length thereof, and has arranged thereon current-collecting brushes not more than one half of the segments. Each brush is electrically connected to the opposed one at the other longitudinal end of the same segment of the armature drum and also to the one at the longitudinal opposed end of an adjacent segment in diagonal fashion progressively.

Abstract: A collector segment comprising a connector lug having a contact surface, to which a wire winding loop of electric machine rotor is to be welded, and extending in a direction radially outward relative to a rotational axis of the electric machine rotor, and positioning surfaces which define a position of the wire winding loop in an extension direction of the connecting lug.

Abstract: A homopolar dynamoelectric machine is provided with plural independent output terminals for selectable external interconnection to yield a variable output. Each output terminal is associated with a respective pair of rotor conductor and stator conductor. Each rotor conductor and stator conductor is of a generally cylindrical shape. Each stator conductor is further comprised of two separated portions each of a generally cylindrically shape. The rotor conductors and stator conductors are arranged concentrically to each other, and all stator conductors are positioned external to all rotor conductors. The surface of each rotor and stator conductor can be skewed to provide a skewed current flow generating a magnetic field boosting that initially provided in the system. Each output terminal has two connections to each stator conductor, one on each separated portion of the corresponding stator conductor. Each such connection comprises plurals contact areas on a corresponding stator conductor.

Abstract: A worn brush detector 43 for an electric generator. The worn brush detector 43 comprises a contactor strip 55 of electrically-conductive material secured to and insulated from a brush holder 28, the contactor strip 55 having a plurality of fingers 52 projecting downward from the strip 55 and generally perpendicular thereto, the fingers 52 being disposed adjacent to a hole 62 in the brush holder 28 and electrically insulated therefrom. An electrically insulated knob 61 on the opposite end of the fingers 52 projects through the hole 62 such that when a brush 25 is inserted into the holder 28 the corresponding finger 52 is pushed away from the holder by the knob 61 contacting the brush 25. When one of the brushes 25 has worn down a predetermined amount the brush 25 is disengaged from the knob 61 so that the corresponding finger 52 is caused to contact the holder 28 to generate an electrical signal.

Abstract: A commutator for an electric machine with reciprocally insulated metal segments is described. At least one groove is made in the segments in the circumferential direction of the commutator and receives an insert formed from a precious metal or electrographite part. The axial width of the inserts only takes up part of the commutator contact surface. Alternatively two inserts are juxtaposed in each segment.

Abstract: A wiper apparatus using a three brush, permanent magnet motor in which a zener diode has a cathode connected to the low speed brush and an anode connected to the high speed brush. The zener breakdown voltage of the zener diode is chosen so that it reverse conducts during at least some portion of each wipe cycle during operation with the high speed brush on a wet window to limit peak wiper speeds and reduce strain on the wiper mechanism. Variations including a transistor, relay or additional zener diode controlled by the zener diode and connected in parallel therewith provide for reduced current and therefore power dissipation in the zener diode at the expense of somewhat limited speed limiting.

Abstract: An improved energy density homopolar generator is disclosed. The generator includes a stator assembly for generating a magnetic field within an interior region and a rotor responsive to the input drive and the magnetic field for generating the output generator voltage. The rotor includes a current generator means that responds to the rotation of the rotor in the magnetic field to collect the current and voltage to output terminals. An energy storage means is also provided with the rotating rotor for storing kinetic energy where the energy storage capacity of a storage means is determined independently of collection of the current and voltage by the current generator means.

Abstract: The electro-mechanical converter, that can be considered a unipolar motor, includes a rotatable rotor made of conductive but low permeability material having two axially spaced, radially protruding integral disks. The first disk is larger than the second disk, and two toroid magnets are disposed on either axial side of the first disk. The two magnets have opposing poles facing each other. The two magnets establish a circumferential, unidirectional magnetic field through the first disk over a radial mid-section of the disk. D.C. current is introduced at the edge of the disk, at a fixed location relative to the rotatable rotor via a mercury bath. The D.C. current is removed from the rotor assembly via the second disk and a second mercury bath.

Abstract: A plurality of circumferentially spaced, compliant, braided metal filament brushes are mounted by the stator of an acyclic generator for extension from the stator collector surface across the liquid metal collector gap into virtual contact with the rotor collector surface. These brushes are each of an axial length corresponding to the axially lengths of the stator and rotor conductive collector surfaces and serve to effectively block the magnetohydrodynamically induced, counter-rotational, circumferential flow of liquid metal in the collector gap, thus eliminating the component of viscous rotor drag otherwise occasioned thereby.

Abstract: A cylindrical outer surface of a commutator is formed with circumferencially extending striations separated by sharp-edged ridges which bite into the abutting surfaces of the brushes engaging the commutator to improve electrical conductivity and reduce static mechanical friction. These striations and the ridges may extend helically so that, on relative movement between the commutator and the brushes, the abutting surfaces of the brushes are scoured. There is also a tendency for the brushes to be moved axially of the commutator, against the restoring force provided by the brush leaf, until this restoring force rises sufficiently to cause the brush to return towards its original axial position so that the surfaces of the brushes and the commutator scrape against each other so as to present fresh surfaces for abutment.

Abstract: Active compensation in the form of a pair of trim coils and passive compensation in the form of a solenoidal-shaped magnetic shunt are disclosed for shaping the magnetic field existing in the liquid metal current collector region of an acyclic generator such as to minimize the field component normal to the stator and rotor collector surfaces and thereby substantially eliminate the generation of circulating currents in the liquid metal medium.

Abstract: To minimize the effects of magnetohydrodynamic surge forces acting on the liquid metal in the collector gap of an acyclic generator, fluid flow impedance members in the form of annular, axially spaced compliant brushes are disposed in the outboard liquid metal containment gap defined between closely spaced, stator and rotor stepped surface formations. These brushes impede the communication to the liquid metal in this containment gap of pressure fluctuations generated in the liquid metal in the collector gap resulting from variations in the generator current transiting the collector gap. A hydrostatic pressure head may thus be maintained consistently at a location intermediate the collector and containment gaps for pumping the liquid metal in a recirculating path.

Abstract: A solenoidal homopolar dynamoelectric machine is provided with inner and outer field coils positioned on opposite sides of a current collecting zone of a rotor which is mounted for rotation with respect to a stator structure. An additional field shaping coil or a tilted brush box current collector is used to conduct current in a circumferential direction near the current collection zone of the rotor to reduce the radial components of magnetic flux in the current collection zone. This reduces circulating currents in the brush assembly.

Abstract: A homopolar dynamoelectric machine is provided with a rotor having a central axis and being mounted for relative rotation with a stator structure that supports a field coil encircling the rotor and has a main pole piece for directing magnetic flux produced by current flowing in the field coil into a first section of the rotor. Brush assemblies which are capable of making sliding electrical contact with a current collection zone of the rotor extend longitudinally adjacent to that current collecting zone and include a plurality of contact elements. These contact elements are packed in an increasing density in a longitudinal direction from one end of the brush assembly to the other end. The use of a variable packing factor for the contact elements of the brush assembly results in more uniform heating of the rotor in the current collecting zone, thereby minimizing the peak rotor temperatures and permitting the machine to operate for longer time periods.

Abstract: A homopolar dynamoelectric machine is provided with current collecting structures which produce a peripheral, circumferential component of load current for self-excitation. The current collection structures include brush boxes which are skewed at a first angle with respect to the rotor axis and a generally cylindrical stator conductor having slits which are skewed at a second angle with respect to the rotor axis. Current flowing in the brushes and stator conductor is forced to have a circumferential component which compensates for rotor saturation due to load current and minimizes the voltage droop characteristic of drum-type homopolar generators.

Abstract: A homopolar dynamoelectric machine is provided with a stator structure having an interior surface defining an internal space for receiving a generally cylindrical rotor which is mounted for rotation with respect to the stator structure. A plurality of brush assemblies are positioned between the stator interior surface and an exterior surface of the rotor and are capable of making sliding electrical contact with the rotor exterior surface. Each of the brush assemblies is connected by way of a brush drive rod to a brush actuator which is positioned on an external surface of the stator structure, to control radial displacement of the brushes. By mounting the brush actuators on an external stator surface, a reduction in stator size and weight is achieved.

Abstract: In an auxiliary device driving motor, at least one of spring pressure to brushes and material of the brushes in contact with a commutator of said d.c. motor, an armature winding and a field winding is changed to obtain output characteristic in which current at non-load revolution is reduced and the engine is started within a high output region of the output characteristic while the auxiliary rotating machine is driven within a low power region.

Abstract: A cover gas recirculator in an acyclic generator having liquid metal collors for reducing entrainment of the liquid metal in the gas. Radial passages in the stator housing provide natural recirculating paths for the cover gas to flow radially outward along the sides of the rotor and return inwardly through the passages. Scoops or lips located inward of the liquid metal collector divert the outward gas flow into the passages to minimize contact of the gas with the liquid metal.

Abstract: A drum type homopolar dynamoelectric machine includes a rotor, a main field coil and an auxiliary field coil. The field coils encircle different portions of the rotor and are supported by a stator structure having a main pole piece for directing magnetic flux produced by current flowing in the main field coil radially into a section of the rotor. A current transfer assembly makes sliding electrical contact with a current collecting zone on the surface of the rotor which is axially positioned between the main and auxiliary field coils. Current flowing in the auxiliary field coil tends to reduce the amount of leakage flux in the current collecting zone produced by current flowing in the main field coil. This reduces undesirable circulating currents in the rotor current collecting zone and the associated current collecting structures.

Abstract: An axial-type homopolar motor having high density, high current fiber brush ollectors affording efficient, low contact resistance and low operating temperatures. The collectors include a ring of concentric rows of brushes in equally spaced beveled holes soldered in place using a fixture for heating the ring to just below the solder melting point and a soldering iron for the local application of additional heat at each brush. Prior to soldering, an oxide film is formed on the surfaces of the brushes and ring, and the bevels are burnished to form a "wetting" surface. Flux applied with the solder at each bevel removes to an effective soldering depth the oxide film on the brushes and the holes.

Abstract: A drum-type homopolar dynamoelectric machine includes a rotor and an annular field coil encircling a portion of the rotor. The field coil is supported by a stator structure having a main pole piece for directing magnetic flux produced by current flowing in the coil, radially into a section of the rotor. A current transfer assembly makes sliding electrical contact with a current collecting zone on the surface of the rotor and is axially positioned between the main pole piece and an end pole piece of the stator which directs magnetic flux axially out of the end of the rotor. A magnetic flux shield is positioned adjacent to the field coil to minimize leakage flux, caused by current flowing in the field coil, in the vicinity of the current collecting zone of the rotor. This reduces undesirable circulating currents in the rotor current collecting zone and the associated current collecting brushes.

Abstract: A current collector having a housing which has a rotatably supported electrical contact shaft having a projecting end that is engageable with a rotating drive shaft, the housing including a mercury contact formed by a space containing mercury, one end of the contact shaft being moveable into the space for contact with the mercury, and a sealing cover for the space.

Abstract: A homopolar generator includes a stator producing a magnetic field and a rotor which rotates in the stator magnetic field to generate electrical discharge current. The current is available from a slip ring surface defined on the rotor, and a plurality of brush mechanisms are provided to collect and transfer the discharge current from the rotor slip ring. Each brush mechanism includes a brush pad for contacting the rotor slip ring. The brush pad is attached to one end of a laminated trailing arm brush strap. A brush actuator forces the brush pad into contact with the rotor slip ring against the yieldable brush lifting force of the brush strap. To compensate for the reaction between adjacent brush straps due to the magnetic fields set up by the discharge current being transferred by each, a conductor strap is electrically connected to the end of the brush strap opposite the attached brush.

Abstract: A submersible electric D.C. motor is provided which has a housing that seals the motor from the surrounding water and holds in a controlled atmosphere which is made to be low in oxygen content and to have free water vapor. Magnetic means are provided to transmit mechanical energy through the housing and liquid means are provided to remove heat from the motor.

Abstract: A small electric motor wherein brushes are disposed on the contact surface of a commutator having a lubricant coated thereon at a predetermined angle with respect to the direction normal to a rotor rotating shaft so that the brushes plow through the lubricant film over a wide area while making slide contact with the commutator, whereby the contact resistance of the brushes is stabilized.

Abstract: Sliding electric contacts are disclosed which may be used, for example, to maintain electrical contact between two moving parts in a rotating machine. Electrical contact between two such parts separated by a constant average distance is maintained during movement of the parts by use of at least one multifilament brush formed as a bundle of thin wires having a fixed end and a free end wherein the free end has a length which is at least 10 percent greater than the constant average distance between the moving parts. The moving parts may be in the form of various configurations of commutators and the electric contacts may be used to maintain electrical contact between the parts within a fluid medium.

Abstract: In a homopolar dynamoelectric machine in which a magnetic flux moves across a generally cylindrical clearance space between the stator and rotor, counterproductive magnetic fields produced by axial electric currents are avoided by providing, on the mutually confronting surfaces of the stator and rotor, nonmagnetic electrical conductors which are electrically insulated from the magnetic portions of the stator and rotor. The conductors are connected together electrically by contacts, providing an electrically conductive loop which encloses no magnetic members. Leads from the electrically conductive loop may be connected to an external circuit.The electrical conductors in one embodiment are of solid cylindrical shape, and in other embodiments are formed of spaced bars as in a squirrel cage. When spaced bars are used, the bars on one member are axially oriented and the bars on the other member are arranged in two sets which are equally but oppositely inclined to the machine axis.

Abstract: The current lead operates at a cryogenic temperature. The collector ring operates at room temperature. While the rotor is being cooled down there is considerable relative movement between them due to thermal contraction. Electrical connection is ensured by interconnecting "rear" or cold side rods with "front" or warm side rodes. The device of the present invention comprises an insulating connector box (12) mounted on the shaft of the rotor. Inside the connector box there are inner and outer pairs of contact blocks (24,23) which clamp onto both a single rear rod (14) and a pair of front rods (16,18). The clamping force is provided by flyweights (28a,b,c). The rotor may thus be cooled to cryogenic temperatures while stationary or rotating slowly since the rods are loosely clamped if at all, and can slide relative to each other. Once working temperatures are reached the rotor is accelerated and the rods are tightly clamped to provide good electrical contact.

Abstract: A stamped and rolled sheet metal bushing having pointed barbs on its exterior periphery and longitudinal ribs on its interior periphery is inserted into the bore of a premolded commutator assembly. An armature shaft is press fit into the bushing assembly, deforming the longitudinal ribs to couple the shaft to the bushing and embedding the pointed barbs into the molded material of the commutator to couple the bushing to the commutator.

Abstract: A moving coil type electromagnetic driving source designed to obtain reliable contact between slide pieces and current supply brushes for supplying current to the moving coil wherein each slide piece is provided with grooves having two inclined surfaces opposed to each other, with an elastic brush having a circular or semi-circular section being provided for each groove such that the brush is in contact with the groove at two points.

Abstract: Sliding electrical contact devices comprising a conducting track and a brush bearing on the track. The brush is formed by at least one bundle of stiff and very fine wires whose diameter is of about 40 microns, tightly retained in a sole piece 14, projecting from the sole piece and slidingly bearing on the track.

Abstract: A commutator for electric machines is disclosed. The commutator comprises a cylindrical body of insulating material having a plurality of lamella segments affixed by means of projecting anchoring elements about the periphery thereof. Each lamella segment is provided at one end with a hook base and hook to the latter of which a coil wire is electrically and mechanically connected by welding. The insulating body has radially and axially projecting ribs which support the respective hook bases of the lamella segments. The width of each supporting rib and associated hook base gradually increases from a point adjacent the hook toward the transition from the hook base to the lamella segment to provide better support and heat conductivity during the process of welding the coil wire to the hook.

Abstract: This invention is a low-drag electrical contact arrangement for establishing continuity between upper and lower spaced members which are subject to relative horizontal movement. In one aspect, the invention comprises an electrical commutating arrangement which includes a horizontally disposed linear electrical commutator. A horizontally movable electrically conductive pedestal is positioned below the commutator and defines a clearance therewith. The pedestal is formed with a cavity confronting the commutator. In the cavity is a bead of electrical conductive liquid, the bead being characterized by an upwardly convex meniscus portion which extends across the clearance and contacts the commutator. The surface tension of the bead is sufficient to maintain the bead intact when the commutator and pedestal are displaced horizontally at speeds from zero to at least twelve inches a minute.

Abstract: The present invention provides an improved system for controlling the location of a ring of sliding electrical contacts relative to a rotor. A magnetic field is generated generally parallel to the axis of the rotor. An electrical conductor has a generally circular portion which is located proximate the ring of sliding electrical contacts and mechanically coupled thereto. An electric current is passed through the circular portion of the conductor to induce radial movement of the circular portion to thereby move the sliding contacts radially with respect to the rotor.

Abstract: A constant supply of liquid metal for a current collector of an acyclic machine is provided by passing armature current radially through a quantity of liquid metal disposed in an annular pumping channel formed between a compliant braided metal filament brush and the stator ring collector surface. A flow restricting plug causes pressure to develop in the circumferentially flowing liquid metal to maintain a constant film of liquid metal in contact with the rotor collector ring and the brush to complete electrical connection therebetween.

Abstract: Flexible wire loop slip ring brushes for use in miniaturized gyroscopes. A lurality of flexible wire loop brushes hug or embrace opposite peripheral sides of respective slip rings in resilient sliding contact over a substantial arc for establishing a redundancy of "a" spots for assured paths through which electrical current may pass with minimal resistance. The rings and the brushes are gold alloy which in sliding contact provide good electrical conductivity and low noise.

Abstract: A homopolar machine comprises a stator provided with channel structures caining liquid metal, a rotor concentrically positioned within the stator with circumferential rotor flanges disposed in the channels, and a porous, resilient braided structure slidably positioned in the channels and immersed in the liquid metal to provide a circumferential wetted surface in intimate contact with the peripheral flange surface. The braided structure comprises a longitudinal strip of braided material supported along its longitudinal edge portions by crimped edges of a braid holder such that the central portion of the braided material is resiliently biased toward the peripheral flange surface. The crimped edges of the braid holder are designed to slide into conforming grooves in the stator channel to facilitate easy replacement of the braided structures. Additional resilience is provided by an additional braided element disposed between the braided material and the braid holder.

Abstract: An active shield is attached to an acyclic machine surrounding stacks of interleaved rotor and stator disks and axially aligned with the main excitation coil disposed within the rotor shaft. The active shield surrounds the magnetic disks of the rotor and stator to interact with the magnetic flux field of the main excitation coil to limit flux density outside the stator to predetermined levels. The active shield may be energized alone to provide emergency operation of the machine. The coil acting as the shield is excited to have a polarity opposite that of the main excitation coil, so that outside the active shield the magnetic fields tend to cancel.

Abstract: A homopolar machine designed to operate as a generator and motor in reversibly storing and transferring energy between the machine and a magnetic load coil for a thermo-nuclear reactor. The machine rotor comprises hollow thin-walled cylinders or sleeves which form the basis of the system by utilizing substantially all of the rotor mass as a conductor thus making it possible to transfer substantially all the rotor kinetic energy electrically to the load coil in a highly economical and efficient manner. The rotor is divided into multiple separate cylinders or sleeves of modular design, connected in series and arranged to rotate in opposite directions but maintain the supply of current in a single direction to the machine terminals. A stator concentrically disposed around the sleeves consists of a hollow cylinder having a number of excitation coils each located radially outward from the ends of adjacent sleeves.

Abstract: A current collector for an electrical machine employs a rotor collector ring encircled by a stator collector ring to which a compliant brush fabricated of an electrically-conductive, liquid metal-permeable material is attached. Liquid metal saturates said liquid metal-permeable material and forms a thin liquid metal film which makes sliding contact with the rotor collector ring, completing contact between the rotor and stator collector rings through the compliant brush. Adequate liquid metal is maintained in the collector by pumping means supplying liquid metal through the stator collector ring.

Abstract: A constant supply of liquid metal for current collectors in an electrodynamic machine is provided by passing armature current radially through a quantity of liquid metal disposed in a circumferential groove in the stator and passing field flux generated by the machine field coil axially through said liquid metal disposed in said groove to act as a pump to circulate said liquid metal. In a disk-type acyclic machine, passages within each stator disk direct a flow of liquid metal from said quantity disposed in said groove in a generally radial direction to maintain a continuous supply of liquid metal to a current collector disposed about the radially-inner surface of said stator disk. Axial passages provide a continuous supply of liquid metal axially from said groove to a current collector disposed axially adjacent said stator disk.

Abstract: An electrical current collector for an acyclic machine employs a stator collector ring which encircles a rotor collector ring and includes a plurality of fins protruding radially-inward from the stator collector ring into a plurality of compliant containment cages, respectively, each cage axially and circumferentially defining a raceway through which liquid metal flows in continuous contact with the rotor collector ring and the stator fin. The walls of the cages are made of resilient nonconductive material and when in a state of compression will exert a continuous bias toward the rotor collector ring.

Abstract: A solid brush current collecting system for dynamo-electric machines which selectively uses compatible materials in different applications for the moving and stationary contact members. Brushes of different compositions are disclosed and the current transfer and collecting members are operated in an inert gas atmosphere, such as carbon dioxide, having either water or organic additives, such as alcohols, hydrocarbons, ketones, and the like, to achieve operation of the current collector system at higher temperatures, higher velocities and higher current densities than is possible with conventional systems. Low friction and low wear rates are in part achieved by operating the contact members in a low temperature environment.

Abstract: An electrical current collector for an acyclic machine employs a rotor collector ring and a stator collector surface connected by a liquid metal current collector having a limited area defined by a nonconductive enclosure for containing conductive liquid metal. Liquid metal is supplied to the enclosure by a passageway through the stator contact area having an orifice within the enclosure area. The enclosure is resiliently mounted upon the stator and spring biased toward the rotor collector ring. The liquid metal making the contact between the rotor collector ring and the stator collector area is maintained under pressure and a limited leakage between the enclosure surface and the rotor collector ring is allowed. The enclosure wall may contain permanent magnets to limit the magnetic affects upon the liquid metal in the current collectors from the excitation field.

Abstract: A method and means for continuously returning degassed and de-emulsified uid metal to the collector sites of high speed acyclic generators is provided. Hydrodynamic pressures developed by the high speed rotating discs are employed to pump liquid current-carrying metal through a plurality of stationary passageways into an interiorly positioned rotating cup or channel where centrifugal forces return purified metal to the collector sites and retain the impure liquid metal.

Abstract: A high power density acyclic machine is described which comprises a plurality of high current density field coils, a series drum and disk arrangement using liquid metal collectors, and shielding members as armature conductor material. The machine achieves maximum flux utilization by providing a plurality of disks connected in series and intersecting the magnetic flux of the field coils, and a drum connected in series between sets of disks also intersecting the flux from the field coils.

Abstract: A constant supply of liquid metal for current collectors in a disk-type acyclic machine is provided by passageways through each stator disk extending from the region adjacent a radially-outer collector to the region adjacent a radially-inner collector. Dynamic pumping of the liquid metal in the region adjacent the outer current collectors is provided by the rotational motion of the rotor disks and by Lorentz expulsion forces acting upon the liquid metal. The openings to said passageways in the region of the outer current collectors are configured to catch a portion of the liquid metal moving with the radially-outer edge of the rotor disks and thereby apply the dynamic pressure of this portion of the liquid metal to move the liquid metal radially-inwardly. Return flow is accommodated by flow paths in the stator separate from those provided for inward flow.

Abstract: A current collector for an electrical machine employs a rotor collector ring encircled by a stator collector ring to which a compliant brush of U-shaped cross section and fabricated of an electrically conductive, liquid metal-permeable material is attached. The region enclosed between the stator collector ring and the brush is filled with liquid metal which seeps outward through the brush interstices, forming on the brush a thin liquid metal film which makes sliding contact with the rotor collector ring, enhancing conductivity between the rotor and stator collector rings through the brush filaments.