EP0066602A1 - Machine homopolaire a circuit ferme - Google Patents

Machine homopolaire a circuit ferme

Info

Publication number
EP0066602A1
EP0066602A1 EP19820900204 EP82900204A EP0066602A1 EP 0066602 A1 EP0066602 A1 EP 0066602A1 EP 19820900204 EP19820900204 EP 19820900204 EP 82900204 A EP82900204 A EP 82900204A EP 0066602 A1 EP0066602 A1 EP 0066602A1
Authority
EP
European Patent Office
Prior art keywords
disk
brush
shaft
conductor
disk conductor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19820900204
Other languages
German (de)
English (en)
Inventor
Adam Douglass Trombly
Joseph Mardell Kahn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ACME ENERGY Co
Original Assignee
ACME ENERGY Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ACME ENERGY Co filed Critical ACME ENERGY Co
Publication of EP0066602A1 publication Critical patent/EP0066602A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K31/00—Acyclic motors or generators, i.e. DC machines having drum or disc armatures with continuous current collectors

Definitions

  • the present invention relates generally to electric generation, and more particularly to a homopolar machine having a high efficiency.
  • the present invention provides a co-rotating homopolar generator that avoids the heating problems of prior machines and renders possible and convenient the generation of electricity at extremely high efficiency.
  • the generator has a rotor comprising a disk conductor and co-rotating coaxial electromagnets on either side.
  • the present invention achieves the improved operation by providing a low reluctance magnetic return path for the magnetic flux that passes through the disk conductor.
  • the low reluctance path permits the electromagnets to produce a high field (limited to 2.2 tesla by the saturation of iron) with a relatively low value of coil excita tion current. Thus overheating is avoided and the full potential of the homopolar generator is achieved.
  • the low reluctance magnetic return path is provided by a relatively high permeability co-rotating enclosure (designated a "flux return enclosure") of sufficient radial and axial dimensions to enclose the magnets and disk conductor of the rotor.
  • the disk conductor itself is preferably constructed from a high permeability, low resistivity material such as iron, and can indeed be integral with the electromagnet cores.
  • Output power is drawn between the periphery of the disk conductor (within the flux return enclosure) and the rotor shaft through fixed disk and shaft brushes.
  • the disk brush protrudes through an annular slot in the flux return enclosure, and is geometrically configured so as not to add a large amount of reluctance to the flux return path.
  • the disk brush is formed with a relatively thin web portion that passes through the enclosure gap. The web portion still has sufficient thickness so that the mechanical strength of the brush is not compromised. Moreover, the web portion has sufficient thickness, and hence conductance, that the saving in magnet power is not offset by excessive ohmic heating in the web portion.
  • Fig. 1 is a sectioned isometric view of a homopolar machine according to the present invention
  • Fig. 2 is an electrical/mechanical schematic view of the homopolar generator
  • Fig. 3 is a sectioned oblique view of the rotor and shaft
  • Fig. 4A is an isometric view showing the construction of the disk brush
  • Fig. 4B is a fragmentary enlarged view showing a portion of the disk brush
  • Figs. 5A and 5B are exploded isometric views of the shaft brushes;
  • Fig. 5C is an isometric view of a shaft brush support;
  • Fig. 6 is a sectioned isometric view of the magnet brush
  • Fig. 7 is a sectioned oblique side view showing the brushes, bearings, and casing, with the rotor shown in phantom;
  • Fig. 8 is a sectioned isometric view of the shaft end seal.
  • Fig. 1 is a sectioned isometric view showing a homopolar generator 10 according to the present invention.
  • Fig. 2 is an electrical and mechanical schematic of the generator system incorporating generator 10.
  • Generator 10 comprises a rotor 12 mounted to a shaft 15 journalled in bearing assemblies 17 and 18 for rotation within a casing 20.
  • the casing maintains rotor 12 within a controlled atmosphere (slightly pressurized nitrogen).
  • One end of shaft 15 protrudes outside casing 20 through a shaft seal assembly 21 and is provided a drive sheave 22 to communicate mechanical energy from a drive motor 25 of any conventional desired type.
  • a shaft end bearing 27 takes up radial loading on drive sheave 22 due to the coupling with motor 25.
  • rotor 12 comprises a central disk conductor portion 30, flanking electromagnet coils 32a and 32b with respective associated iron core portions 35a and 35b, and a flux return enclosure having enclosure halves 37a and 37b.
  • the disk may more closely resemble a cylinder.
  • the term "disk" will still .he used for the conductor that corresponds to the disk of
  • Electromagnet coils 32a and 32b are series connected between shaft 15 and an electrically isolated shaft portion 40. Excitation current is provided by a magnet excitation power supply 42 which is coupled between a magnet brush 45 which rubs on electrically isolated shaft portion 40, and a pair of parallel connected shaft brushes 47 and 48. An outer portion of disk conductor 35 engages a disk brush 50 and output power is drawn between disk brush 50 and shaft brushes 47 and 48.
  • generator 10 has the capability of operating at extremely high efficiency.
  • Rotor and Shaft Referring to the sectioned. oblique view of Fig. 3, the detailed construction of rotor 12 and shaft 15 may be seen.
  • Disk conductor portion 30 and electromagnet core portions 35a and 35b are constructed of high permeability, low resistivity material such as iron, and may be integrally formed as a single iron rotor core, designated 55.
  • Rotor core 55 is brazed to shaft 15 which is preferably made of a copper-beryllium alloy.
  • a suitable shaft material may be obtained from Brush Wellman Company under the name Brush 3 Alloy. This is an alloy characterized by a high electrical conductivity (50% of copper standard) and a high modulus of elasticity.
  • a circumferentially extending copper contact 57 is brazed to the outer surface of rotor core 55 at the axial midpoint thereof and contacts disk brush as will be described below.
  • Electromagnet coils 32a and 32b are wound with epoxy-impregnated wire which may be No. 12 size in the illustrative embodiment.
  • Iron annuli 60a and 60b are bolted to opposite ends of rotor core 55 to define therewith a spool which axially confines the coils.
  • the series connection between isolated shaft portion 40 and shaft 15 is defined by first, second, and third magnet conductors 62, 63, and 64.
  • First magnet conductor 62 runs from shaft portion 40 along the axis of shaft 15, and then radially outward to coil 32b.
  • Second magnet conductor 63 runs between coils 32a and 32b, passing through brush contact 57.
  • Third magnet conductor passes radially outward from coil 32a to shaft 15.
  • Electromagnet coils 32a and 32b are provided with respective high tensile strength wrappings 65a and 65b, preferably fiberglass-epoxy tape, to prevent centrifugal destruction of the coils.
  • the flux return enclosure provides a low reluctance magnetic path for the magnetic flux lines passing through rotor core 55 and should therefore be made of relatively high permeability material.
  • enclosure halves 37a and 37b may be constructed of medium-high permeability, high tensile strength, forged silicon steel.
  • Enclosure halves 37a and 37b are bolted to rotor core 55, and together define a cylindrical enclosure within which are located electromagnet coils 32a and 32b, rotor core 55, copper brush contact 57, and magnet coil wrappings 65a and 65b.
  • enclosure halves 37a and 37b Facing portions of enclosure halves 37a and 37b are spaced apart to define a circumferentially extending slot 66 that permits disk brush 50 to engage copper contact 57.
  • Slot 66 is approximately 9/32-inch thick in the region between enclosure halves 37a and.37b, but broadens to approximately 1.0 inch thick in the region between electromagnet coils 32a and 32b.
  • Enclosure halves 37a and 37b are provided with respective high tensile strength wrappings 67a and 67b.
  • shaft 15 is characterized by a 2-inch diameter in the rotor region. Axially away from rotor 12, shaft 15 is of lesser diameter, being reduced to 45 millimeters in the region of bearing assemblies 15 and 17. Proceeding axially away from rotor 12 in a first direction toward isolated shaft portion 40, shaft 15 is formed with radially relieved portions 68 and 69 to define therebetween a first annular collar 70 for engagement with shaft brush 47.
  • shaft 15 is formed with an annular groove 71 spaced from the shaft end to define a second annular collar 72 for engagement with shaft brush 43. Brushes
  • Fig. 4A is an isometric view showing the construction of disk brush 50.
  • Disk brush 50 comprises symmetrical halves 75a and 75b which, when bolted together in coplanar relationship, completely encircle rotor 12.
  • Disk brush half 75b is shown only in phantom. Since disk brush halves 75a and 75b are similarly constructed, brush half 75a only will be described.
  • Brush half 75a is in the form of a 1-inch thick rigid copper plate with a semicircular opening 77 along an edge thereof, opening 77 being adapted to cooperate with a similar opening in brush half 75b to form a circular aperture.
  • a semi-annular web portion 80 of reduced thickness surrounds opening 77 in a spaced concentric relation thereto, and defines an inner brush portion 82 between opening 77 and web portion 80.
  • Web portion 80 is approximately 1/4-inch thick while inner brush portion 82 is approximately 13/16-inch thick.
  • Web portion 80 has a radial extent that is only slightly greater than the radial extent of the facing portions of flux return enclosure halves 37a and 37b and their associated wrappings 72a and 72b.
  • web portion 80 is sized to fit within slot 66 of rotor 12 with a small clearance (for example l/64th inch on either side).
  • Inner brush portion 82 is sized to fit within the broadened slot portion between electromagnet colis 32a and 32b, and engages brush contact 57.
  • Axial clearances are somewhat broader than those surrounding web portion 80.
  • a clearance of 3/32-inch on either side is suitable.
  • the brush halves are not critical, nor are the particular outside configurations. However, it is important that the brush halves have portions that extend sufficiently beyond the outside surface of rotor 12 to permit proper mechnical support with respect to casing 20. A height of 18 inches and a width of 10.5 inches (total brush width of 21 inches) is suitable.
  • inner brush portion 82 carries a fixed contact assembly 85, which may be seen with reference to the fragmentary oblique sectional view of Fig. 4B. More particularly, inner brush portion is formed with an inwardly opening recess 37 which broadens beneath the surface to define opposing lips 90 and 91 spaced to receive copper contact 57 therebetween.
  • Lips 90 and 91 confine fixed contact assembly 85 which comprises a strip of ground braid material 92 (1/2-inch x 1/16-inch cross-section is suitable) and a copper strap 95 that is crimped around it to provide structural integrity. Strap 95 surrounds ground braid strip 92 to the same extent as lips 90 and 91, so that the inwardly facing portion between the lips is exposed ground braid material which engages contact 57.
  • ground braid strip 92 is wetted with a liquid metal such as a sodium/potassium eutectic (NaK-78). Operation is optimum with a small and precisely controlled clearance (e.g., 0.002 inches) between braid strip 92 and contact 57.
  • Figs. 5A and 5B are exploded isometric views of shaft brushes 47 and 48. Turning first to Fig.
  • shaft brush 47 is of two-piece construction including an elongated rectangular bar member 100 (1-inch x 4-inch cross-section) and an abutting short member 102, members 100 and 102 having respective semicircular openings 105 and 107 along facing, abutting edges thereof.
  • the surface of the circular bore is recessed and houses a contact assembly 112
  • brush portion 82 (which may comprise eutectic wetted braid) in the same manner as inner brush portion 82 houses contact assembly 85. If braid material is used, a 3/4-inch x 1/16-inch cross-section is suitable.
  • Contact assembly 112 engages annular collar 70 to conduct current between shaft 15 and shaft brush 47.
  • the outside dimensions of brush members 100 and 102 are not critical, but brush member 100 is preferably of sufficient length to extend outside casing 20.
  • shaft brush 48 includes cooperating brush members 120 and 125 which are generally the same as brush members 100 and 105 with the exception that the semicircular, bores do not extend all the way through, but rather terminate within the brush members.
  • a contact assembly 127 engages annular collar 72.
  • Fig. 5C is an isometric view of one of two identical support elements 130 for shaft brushes 47 and 48.
  • Support element 130 is formed of insulative material and provides an electrically insulated mounting of the shaft brushes to housing 20.
  • Support element 130 includes a rectangular channel section 131 for receiving and supporting a respective shaft brush and a flange section 132 for mounting to housing 20.
  • Fig. 6 is an isometric sectional view illustrating the construction of isolated shaft portion 40 and magnet brush 45.
  • Magnet brush 45 is a cylindrical element of sintered copper-graphite or equivalent material.
  • conductor 62 runs in an axial bore along shaft 15.
  • the end of shaft 15 is formed with a cylindrical recess into which is epoxied an undersized metal cylinder 135 which is bored to receive an uninsulated end of magnet conductor 62.
  • Isolated shaft portion 40 is a circular plate of the same diameter as the adjacent portion of shaft 15, and is soldered to cylinder 135 to form a mechanical and electrical coupling thereto. Housing
  • Fig. 7 is a side oblique view, sectioned vertically along the axis of rotor 12, with the shaft and rotor shown only in phantom.
  • Figs. 1 and 7, taken together, show the construction of housing 20, bearing assemblies 17 and 18, and the mechanical support of the disk, shaft, and magnet brushes.
  • Housing 20 comprises a central rotor chamber 150 and axially outboard shaft brush chambers 152 and 153.
  • Rotor chamber 150 includes a pair of end walls 155a and 155b, and a pair of side panels 157a and 157b.
  • Shaft brush chamber 152 includes a pair of side walls 160a and 160b, and an end panel 162, while shaft brush chamber 153 includes a pair of side walls 165a and 165b, and an end panel 167.
  • Housing 20 further comprises a floor 170 and a roof 172.
  • End walls 155a and 155b, side walls 160a and 160b, side walls 165a and 165b, and floor 170 are preferably 1/2-inch stainless steel plate and are welded together to provide a rigid load-bearing assembly.
  • Side panels 157a and 157b, end panels 152 and 157, and roof 172 are of lighter material such as 1/8-inch stainless steel, and are bolted in place so as to be removable.
  • Disk brush halves 75a and 75b are supported between a lower brush support channel 175 and an upper brush support channel 177, both of which are fabricated from a fiber reinforced thermosetting plastic material.
  • Lower brush support channel 175 sits on floor 170 while upper brush support channel 177 is bolted to appropriate structural angle members, not shown.
  • Shaft end bearing 27 is mounted to a housing extension 178 which carries a magnet brush support bracket 179.
  • Magnet brush 45 is held in a cylindrical bore within an insulating brush support block 180, and is kept in contact with isolated shaft portion 40 by a spring 181.
  • Bearing assemblies 17 and 18 are mounted into, and supported by respective end walls 155a and 155b. Since the bearing assemblies are generally identical, only one will be duplex pair of angular contact ball bearings 180a and 180b mounted within a rectangular housing 183 having a mounting flange 185 on three sides thereof. Suitable bearings may be obtained from Fafnir Company under the designation 2MM209 WI CR DUL. These are very high precision grade (ABEC-7) bearings characterized by a 1.7717-inch bore, a 3.3465-inch outer diameter, and a 1.4960-inch width. These bearings are able to run at 8,000 r.p.m. in grease under the loading imposed by rotor 12 and shaft 15.
  • Shaft end bearing 27 may be a prehoused two-bolt flanged unit such as that obtainable from SKF under the designation FYTP-100. This is a bearing having a 1.0000 inch bore and capable of operation at 8700 r.p.m. in grease. Such a bearing has labyrinth seals which do not actually touch, thus avoiding problems of excessive wear and heating at high speeds.
  • Fig. 8 is a partially cut away isometric view showing the details of shaft seal assembly 21 which maintains a seal during operation when casing 20 is filled with slightly pressurized nitrogen.
  • Shaft seal assembly 21 comprises an elastomeric seal 195 held in place within a shaft seal housing 196 by a retaining plate 197.
  • a suitable elastomeric seal may be obtained from Johns-Manville Company under the designation 10058LUP, which signifies a seal fabricated from buna-N material and characterized by a 2.0000-inch outer diameter, a 1.2500-inch bore, and a 0.3750-inch width. At the high angular velocity of operation, the elastomeric seal would rapidly wear away portions of the beryllium-copper material of shaft 15.
  • shaft 15 is provided with a stainless sleeve 198, such as that obtainable from Chicago Rawhide under the designation 99125 Speedi-Sleeve.
  • a stainless sleeve 198 such as that obtainable from Chicago Rawhide under the designation 99125 Speedi-Sleeve.
  • This is a sleeve characterized by 1.250-inch bore, and a 0.010-inch wall thickness with a special outer finish designed expressly for efficient sealing action.
  • B is the magnetic field strength
  • ⁇ is the angular velocity of the rotor
  • r 2 is the rotor core radius
  • r 1 is the shaft radius.
  • the voltage may be shown to be equal to approximately 2-9 volts.
  • the total internal resistance of the generator is in the neighborhood of 6-10 micro-ohms. Assuming that the machine is capable of dissi maximum test load current is about 15 kiloamperes. At this current, the power output is 43.7 kilowatts. However, the anticipated load current permissible for continuous operation may be more realistically in the neighborhood of as low as 8 kiloamperes, which corresponds to a power output of 23.3 kilowatts. As stated above, motor 25 may be any suitable prime mover, and for the operating conditions described herein, should be capable of developing approximately 15 horsepower. In view of of the present invention and the operation of generator 10, the advantages of the configuration of rotor 12 may be understood.
  • enclosure halves 37a and 37b cooperate with rotor core 55 to provide a low reluctance magnetic circuit. That is, energization of coils 32a and 32b causes magnet flux lines, denoted schematically by loops 220 in Fig. 3, that are contained within a low reluctance magnet circuit comprising a substantially closed path of high permeability material.
  • the only high reluctance portion is slot 66 which is kept as narrow as possible consistent with web portion 30 of brush halves 75a and 75b having sufficient mechanical strength and electrical conductance.
  • a generator according to the present invention is characterized by high efficiency and low magnet power requirements, achieved by the use of a rotor configuration having a low reluctance path.
  • housing 20 could be constructed with a cylindrical configuration to minimize the internal volume.
  • brush geometry that encircles the rotor and shaft is desirable, other configurations could be used. Therefore, the above description and illustration should not be construed as limiting the scope of the invention which is defined by the appended claims.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc Machiner (AREA)

Abstract

Un generateur homopolaire co-rotatif possede un rotor (12) comprenant un conducteur a disque (30) et des electro-aimants coaxiaux co-rotatifs (32a et 32b) de chaque cote, et possede un fonctionnement ameliore en utilisant un circuit de retour magnetique de faible reluctance pour le flux magnetique qui passe au travers du conducteur a disque (30). Le circuit de faible reluctance permet aux electro-aimants (32a et 32b) de produire un champ de haute intensite avec une valeur du courant d'excitation de la bobine relativement faible. Par consequent, le surchauffage est elimine et le potentiel total du generateur homopolaire est obtenu. Le circuit de retour magnetique de faible reluctance (220) est forme de preference par une enceinte co-rotative de permeabilite relativement elevee (ayant des moities d'enceintes (37a et 37b) de dimensions radiales et axiales suffisantes pour contenir les electro-aimants et le conducteur a disque du rotor. Le conducteur a disque (30) est construit de preference avec un materiau de grande permeabilite, de faible resistivite, telle que le fer, et peut evidemment etre solidaire des noyaux des electro-aimants (35a et 35b).
EP19820900204 1980-12-11 1981-12-01 Machine homopolaire a circuit ferme Withdrawn EP0066602A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US21546380A 1980-12-11 1980-12-11
US215463 1980-12-11

Publications (1)

Publication Number Publication Date
EP0066602A1 true EP0066602A1 (fr) 1982-12-15

Family

ID=22803080

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820900204 Withdrawn EP0066602A1 (fr) 1980-12-11 1981-12-01 Machine homopolaire a circuit ferme

Country Status (2)

Country Link
EP (1) EP0066602A1 (fr)
WO (1) WO1982002126A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4885526A (en) * 1988-03-18 1989-12-05 Electro Erg Limited Compensation circuit for electrical generators
US5587618A (en) * 1993-04-15 1996-12-24 Hathaway; George D. Direct current homopolar machine
US6515391B2 (en) 1999-05-20 2003-02-04 The United States Of America As Represented By The Secretary Of The Navy Electricity generator with counter-rotating collectors in a radial magnetic field
US6603233B2 (en) 2001-07-20 2003-08-05 Bryan W. Strohm Electrical generator

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2408080A (en) * 1942-02-26 1946-09-24 Edward C Lloyd Power transmission device
US2845554A (en) * 1955-03-30 1958-07-29 Commissariat Energie Atomique Devices for ensuring an electric contact between rotary parts of an electric machine
FR1326439A (fr) * 1962-03-19 1963-05-10 Centre Nat Rech Scient Perfectionnements apportés aux procédés et machines pour engendrer des courants électriques très élevés
US3185877A (en) * 1963-01-14 1965-05-25 Sears Anthony Direct current homopolar generator
GB1165538A (en) * 1966-01-12 1969-10-01 Internat Res And Dev Company L Improvements in and relating to Homopolar Electric Machines
US3736450A (en) * 1971-11-17 1973-05-29 R Emaldi Unipolar double inductor dynamo
GB1475687A (en) * 1973-05-25 1977-06-01 Int Research & Dev Co Ltd Homopolar dynamo-electric machines

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8202126A1 *

Also Published As

Publication number Publication date
WO1982002126A1 (fr) 1982-06-24

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Inventor name: KAHN, JOSEPH MARDELL

Inventor name: TROMBLY, ADAM DOUGLASS