Induction Patents (Class 310/166)
  • Patent number: 4651040
    Abstract: An induction motor is suggested with a permanent magnet rotor and a stator which is excited electromagnetically by an alternating field, whereby an electrically conductive rotor outer part (17) is mounted between a freely rotatable permanent magnetic rotor inner part (16) and the stator poles (11,12) in the form of a hollow cylinder or a short circuit cage. The rotor outer part (17) rotates in form of a cage runner asynchronous and drives the connected load, after the start of the permanent magnetic inner part (16) which runs synchronous in the continuous operation. A rotating direction arresting device (36,37) assures a defined rotating direction of a drive shaft (27).
    Type: Grant
    Filed: August 7, 1985
    Date of Patent: March 17, 1987
    Assignee: Robert Bosch GmbH
    Inventors: Bruno Gerstner, Rudiger Pfeiffer, Berthold Seng
  • Patent number: 4644208
    Abstract: An induction motor for a motor-centrifugal pump unit has a stator shaped to provide a spherical airgap. The stator winding lies between teeth which extend radially of the spherical stator surface. The teeth are formed of built up strips of magnetic laminations wound in a spiral and placed against the stator yoke.
    Type: Grant
    Filed: November 2, 1984
    Date of Patent: February 17, 1987
    Inventor: Nikolaus Laing
  • Patent number: 4620120
    Abstract: A stator design for a spherical gap motor having a stator and rotor wherein the lamination strips which make up the teeth of the stator are formed as portions of a cylindrical wall. Each of the lamination strips is concentric about the axis of rotation of the rotor. At the axial end of the lamination strips nearest the rotor pole-shoes are formed as a T-shaped end on the laminations. The ends of the lamination strips are provided with recesses in order to closely position adjacent strips. The recesses are adapted to receive lamination strips of adjacent pole-shoes in order to decrease the approach angle of the lamination to the pole-shoe. The ratio between the area of two adjacent pole-shoes which are exposed to the magnetic flux gap is the same ratio as the cross-sectional area of the respective lamination strips in a plane of rotation.
    Type: Grant
    Filed: November 2, 1984
    Date of Patent: October 28, 1986
    Inventor: Karsten Laing
  • Patent number: 4614887
    Abstract: To provide a dynamo electric machine, for combination, preferably, with a centrifugal circulating pump, having a rotor which is at least part-spherical, the stator is formed of edge-wound strip material, in which the stator part is a continuous strip of L-shape deformed strip, with notches (9') cut into the L prior to deformation, the bending edge (15) of the L changing throughout the length of the strip, uniformly, with uniform change of the spacing of the notches so that, as the strip is wound over a part-spherical form which defines an air gap between the rotor and stator, the width of the teeth between adjacent notches (9') will increase to define continuous through-slots (9) for the windings, and the bending corner (15) likewise will change from a position near the root of the notches (9') to a position within the solid portion of the second leg (18) of the L.
    Type: Grant
    Filed: December 10, 1984
    Date of Patent: September 30, 1986
    Assignee: Robert Bosch GmbH
    Inventors: Peter Ahner, Helmut Harer, Siegfried Schustek
  • Patent number: 4613477
    Abstract: The invention provides an electromagnetic technique for repositioning garter springs, located between the coolant tubes and calandria tubes of fluid cooled nuclear reactors in which the garter springs are not directly accessible by mechanical means. An electromagnetic coil is advanced along the selected fuel channel to a position adjacent the garter spring, and a current pulse is passed through the coil thereby to exert an electromagnetic repulsive force on the garter spring having a component in the direction of the required displacement.
    Type: Grant
    Filed: March 22, 1984
    Date of Patent: September 23, 1986
    Inventor: Joseph H. Dableh
  • Patent number: 4599530
    Abstract: A magnetic machine of spherical-gap type includes a bearing arrangement of a rotating member having convex and concave elements. An other radially disposed bearing is concentrically arranged with the abovementioned bearing arrangement to form a gap which limits the angle of wobble of the rotating member and preventing the angle from increasing once the rotating member contacts the radially disposed member.
    Type: Grant
    Filed: November 2, 1984
    Date of Patent: July 8, 1986
    Inventor: Karsten Laing
  • Patent number: 4593219
    Abstract: Pole shoe elements for widening the teeth of an electrical machine of spherical-gap type. The machine includes a plurality of teeth. Each tooth has a groove, so that H-shaped element with a strap is adapted to fit within a groove of each tooth. A plurality of such shoe elements forming a ring by a connection strap between adjacent pole shoe elements.
    Type: Grant
    Filed: November 2, 1984
    Date of Patent: June 3, 1986
    Inventor: Karsten Laing
  • Patent number: 4593215
    Abstract: Rotary devices comprising rotor and stator elements are provided with rotational energy by an adaptation of the principle of the polyphase induction motor. Divided stator windings are provided to enable the rotary device to induce essential currents in the rotor windings without the production of undesirable and destructive currents in the rotary element proper.
    Type: Grant
    Filed: May 23, 1980
    Date of Patent: June 3, 1986
    Inventor: Eric A. Salo
  • Patent number: 4541575
    Abstract: A method of winding brushless motors is disclosed. According to the method one turn of the winding is applied to each phase of a multi-phase motor, then, a second turn is applied to each of the phases, etc., until the required number of turns are wound. The method results in a layered winding having a minimum of end turned build-up and excellent inductance balance between phases of the winding. Because the winding for each phase is continuous, a high reliability winding is produced.
    Type: Grant
    Filed: September 14, 1982
    Date of Patent: September 17, 1985
    Assignee: Kollmorgen Technologies Corp.
    Inventor: Ray Dickerson
  • Patent number: 4503377
    Abstract: A variable speed rotary electric machine comprises a stator composed of a stator core and first and second stator windings wound on the stator core, and a cage rotor mounted rotatably within the stator and composed of a rotor core and rotor conductor disposed in a squirrel-cage configuration. The first stator winding is connected to an AC power supply of a fixed frequency. The second stator winding is connected to a power supply of a variable frequency. The first and second stator windings are so wound as to form, respectively, numbers of poles differing from each other. The rotor conductors of the cage rotor are electromagnetically coupled with the magnetic flux generated by the first and second stator windings, respectively, and so disposed as to form a number of poles which is intermediate between the number of the poles formed by the first stator winding and the number of poles formed by said second stator winding.
    Type: Grant
    Filed: January 4, 1984
    Date of Patent: March 5, 1985
    Assignee: Hitachi, Ltd.
    Inventors: Yukio Kitabayashi, Noriyoshi Takahashi, Masatoshi Watanabe, Toshiaki Okuyama, Yoji Tanaka
  • Patent number: 4488077
    Abstract: An asynchronous electric machine, having an iron core mounted on a shaft, squirrel bars and a short circuit ring connecting the bars at both ends of the rotor, and a stator having a coil winding provided with end turns exterior of the stator. A conductive body made of magnetizable or non-magnetizable material is mounted in the field of the stray magnetic flux pattern formed by the end-turns and the short circuiting ring, to increase losses, and thereby increase starting torque.
    Type: Grant
    Filed: December 3, 1981
    Date of Patent: December 11, 1984
    Assignee: Ganz Villamossagi M/u/ vek
    Inventor: G/a/ bor Kov/a/ cs
  • Patent number: 4482832
    Abstract: A shaded pole lamination is disclosed which includes a rotor opening positioned asymmetrically with respect to the sides of the lamination so as to increase the metal available to carry the magnetic flux on the side of the main pole which is farther from the main coil. In addition, shading coil recesses are provided which are grouped with respective reluctance gaps and crowded into the region near the reluctance gaps in order to maximize the area of the main poles. The shape of the lamination adjacent the reluctance gap has been modified to further increase operating efficiency.
    Type: Grant
    Filed: March 31, 1983
    Date of Patent: November 13, 1984
    Assignee: Rival Manufacturing Company
    Inventor: Paul Minton
  • Patent number: 4471253
    Abstract: Without exception, the iron sheets of the stator teeth of electric motors are up to now produced by stamping. The invention relates to electric motors in which the stack of iron sheets of the stator is largely composed of rectangular metal sheet strips cut from a strip.
    Type: Grant
    Filed: July 12, 1982
    Date of Patent: September 11, 1984
    Inventor: Karsten Laing
  • Patent number: 4464618
    Abstract: A single phase induction motor of the capacitor start, capacitor run type, has a rotor and stator of conventional polyphase design and a two phase stator winding comprising a main winding with approximately 70% as many turns as a comparable conventional single phase induction motor and an auxiliary winding in series with the main winding, the auxiliary winding having two branches wound in opposite directions, each branch having substantially the same number of turns as the main winding. One branch of the auxiliary winding is connected in series with a running capacitor and this combination is in turn connected in parallel with the other branch. The series arrangement of the main and auxiliary winding is connected to the supply line and a starting capacitor may be paralleled with the running capacitor during starting for improved starting torque in the conventional capacitor start manner.
    Type: Grant
    Filed: September 15, 1982
    Date of Patent: August 7, 1984
    Inventor: James F. Shoemaker
  • Patent number: 4458167
    Abstract: An electric motor comprising a rotor rotating around an axis and a stator. The rotor and the stator each comprise a set of dipolar pieces regularly distributed around their respective periphery, one of these sets being inside a circle centered on the axis, the other set being outside of the same circle. Each of these sets has a different number of dipolar pieces. The motor further comprises a controlling system associated with one of the sets, preferably the stator, to furnish current coils wound on the dipolar pieces of this set so as to selectively magnetize these pieces and thus form a rotating magnetic field. In accordance with the invention, each dipolar piece has a longitudinal axis extending perpendicular to a given radius of a circle lying in a plane perpendicular to the axis of the rotor.
    Type: Grant
    Filed: September 30, 1982
    Date of Patent: July 3, 1984
    Inventor: Gilles Leveille
  • Patent number: 4409506
    Abstract: When an induction motor is speed-controlled with a variable frequency power supply including thyristor inverters, operating loss due to harmonics components is increased in a rotor of the induction motor. In order to diverge additional operating loss into an appreciable depth of the rotor to thereby suppress the increase in the operating loss, the rotor comprises a cylindrical member having a circumferential resistivity which is larger than axial and radial resistivities and circumferential permeability which is smaller than axial and radial permeabilities, and a core disposed in the cylindrical member and having an axial permeability which is smaller than circumferential and radial permeabilities.
    Type: Grant
    Filed: July 27, 1981
    Date of Patent: October 11, 1983
    Assignee: Hitachi, Ltd.
    Inventors: Motoya Ito, Noboru Fujimoto, Noriyoshi Takahashi, Masatoshi Watanabe, Seizi Yamashita
  • Patent number: 4371802
    Abstract: A balanced, half-pitch capacitor induction motor having a stator core member with equally spaced teeth equal in number to twice the number of motor poles and with the inner ends of the teeth having equal angular extent, and a squirrel cage rotor member. The main field winding comprises serially connected coils equal in number to the number of motor poles respectively embracing alternate, consecutive ones of the teeth and being adapted to be connected across a single phase source of alternating current. An auxiliary field winding comprises serially connected coils embracing consecutive teeth intermediate the teeth having the main winding coils thereon, the auxiliary winding coils being serially connected with a phase-displacing capacitor across the serially connected main winding coils. The main and auxiliary windings have equal ampere turns and equal pitch thereby providing a balanced, half-pitch, two phase motor winding. The rotor member has its squirrel cage bars spiraled by one-tenth of a full turn, i.e.
    Type: Grant
    Filed: June 8, 1981
    Date of Patent: February 1, 1983
    Inventor: Wayne J. Morrill
  • Patent number: 4338557
    Abstract: In a polyphase machine, being either a motor or a generator, there is provided a stator core having main stator windings wound about the stator core and main windings having a capacitor connected in series with each winding of the core. Switches are provided for each winding, and a trigger source for the switches operates with the capacitor and windings to ensure sequential current flow in opposite directions across the windings. Variable frequency pulses from a trigger results in a variable speed machine. With control windings wound on the stator, oppositely to the main windings there are currents in each phase which are substantially in-phase at no load with the currents of the corresponding radially adjacent the main windings. Such currents become out of phase with their main winding currents as the load increases. At low load the net flux density is low and as the load increases the flux density increases.
    Type: Grant
    Filed: August 14, 1979
    Date of Patent: July 6, 1982
    Inventor: Cravens L. Wanlass
  • Patent number: 4316112
    Abstract: An inductor alternator having a stator formed from an annular yoke with laminated pole pieces secured to the internal periphery thereof by welding through slots in the yoke. The rectifiers for rectifying the alternating current are located in a detachable compartment at one end of the housing containing the stator. The rotor is journaled within the stator by bearings supported in said detachable compartment.
    Type: Grant
    Filed: May 10, 1979
    Date of Patent: February 16, 1982
    Assignee: The Commonwealth of Australia, Department of Productivity
    Inventors: John M. Waldron, Frederick J. Nott, Laurence C. Harrison, Graham D. Johnson, Malcolm D. Green
  • Patent number: 4307309
    Abstract: A brushless alternator or like dynamoelectric machine, particularly adapted for use in a vehicle, comprising a field coil mounted on the center leg of a stationary core, a rotor shaft extending through the center leg of the core, a first, disc-shaped rotor member mounted on the shaft and facing the center leg of the core across a first large-area axial air gap and having a first set of radially projecting rotor poles, and a second, annular rotor member mounted on the first rotor member, facing an outer flange portion of the core across a second large-area axial air gap and having a second set of axially projecting rotor poles interleaved one-for-one with the first set.
    Type: Grant
    Filed: January 29, 1980
    Date of Patent: December 22, 1981
    Inventor: Edward L. Barrett
  • Patent number: 4292559
    Abstract: In an induction and universal motor combined in a common lamination stack and supplied from a single phase line in line with a single armature winding system common to universal commutator motor as well as to induction motor operation, there are connected to the same segments of the commutator a crossed lap winding and an uncrossed lap winding, the coil span of which corresponds approximately to one pole pitch of the low pole and, in particular, two pole commutator stator winding and to an uneven integral multiple of the high pole induction motor stator winding, to provide a motor particularly suited for driving automatic washing machines.
    Type: Grant
    Filed: October 2, 1978
    Date of Patent: September 29, 1981
    Assignee: Siemens Aktiengesellschaft
    Inventors: Herbert Auinger, Peter Bradler, Rudolf Weppler, Jaroslav Stepina
  • Patent number: 4211946
    Abstract: In an asynchronous machine including a rotor of solid iron and a squirrel cage winding, the rotor is further provided with closed slots of any cross sectional shape which receive the bars of the squirrel cage winding whose upper edge is spaced from the outer surface of the rotor by a distance which is equal to the depth of penetration a of the eddy currents generated for a given starting voltage and for a slip s.gtoreq.0.8.
    Type: Grant
    Filed: April 18, 1978
    Date of Patent: July 8, 1980
    Assignee: Siemens Aktiengesellschaft
    Inventors: Joachim Eckert, Franz Spirk
  • Patent number: 4208596
    Abstract: A linear induction motor comprising an inductor formed of individual transversal laminations surrounded by a main polyphase concentrated winding and provided with rods interconnected by means of a yoke. It also comprises a secondary element with respect to which the inductor moves. The secondary element has an electrically conductive part arranged on a magnetically conductive base. Each lamination is provided with two additional polyphase windings the magnetizing force of which sets up magnetic fields travelling in opposite directions transversely of inductor movement. The end faces of the lateral rods of the core structure are provided with slots arranged on the side of the secondary element and adapted to receive the additional polyphase windings.
    Type: Grant
    Filed: October 18, 1978
    Date of Patent: June 17, 1980
    Inventors: Alexandr D. Popov, Vladimir A. Solomin
  • Patent number: 4181868
    Abstract: An alternating current electric machine, namely, a small-power asynchronous otor, has two pairs of electric poles which can be supplied with either three-phase or single-phase alternating current. The machine is considerably simpler than classic motors, being provided with a stator having single cylinder poles and four or six coils. The stator is made from grain-oriented steel sheet.
    Type: Grant
    Filed: May 17, 1978
    Date of Patent: January 1, 1980
    Assignee: Institutul de Cercetari Pentru Industria Electrotehnica - ICPE
    Inventor: Stefan I. Grosu
  • Patent number: 4177395
    Abstract: This invention relates to an electrically operated actuator for quarter-turn valves, such as butterfly or ball valves.The actuator includes a single phase 2-pole dynamo-electric machine comprising a stator having three windings and a rotor having a plurality of short-circuited windings. The rotor is coupled directly with the output shaft and the windings of the stator are energised from a power supply through respective limit switches which are cam controlled by the output shaft.One of the stator windings controls the final movement of the actuator in each direction of travel and the limit switch for this winding is broken to de-energize the winding by an adjustable stop mechanism.
    Type: Grant
    Filed: December 19, 1977
    Date of Patent: December 4, 1979
    Assignee: Rotork Limited
    Inventor: Donald L. Hore
  • Patent number: 4160181
    Abstract: To generate auxiliary electric energy on a suspension vehicle, a generator is driven by a magnet pole wheel, which is set in rotation by utilizing the eddy current effect upon movement relative to an electric conductor rail.
    Type: Grant
    Filed: August 30, 1977
    Date of Patent: July 3, 1979
    Assignee: Siemens Aktiengesellschaft
    Inventor: Alfred Lichtenberg
  • Patent number: 4156821
    Abstract: A single phase induction motor of a capacitor run type comprising: a stator including a stator core having a circle aperture and a plurality of slots formed extending in the axial direction of the aperture whereby a plurality of teeth are formed therebetween, two main winding coils wound around two teeth to form two main excited poles of the same polarity at the diametrical positions of the stator core, the two main excited poles of one polarity causing two main image poles of the opposite polarity at the positions between the excited poles, two auxiliary winding coils wound around two teeth, shifted by one tooth from those of the main winding coils, to form two auxiliary excited poles of the same polarity at the diametrical directions of the stator core, the two auxiliary excited poles of one polarity causing at least two auxiliary image poles of the opposite polarity at the positions between the auxiliary excited poles, whereby two pairs of main and auxiliary excited and image poles are formed sequentially
    Type: Grant
    Filed: April 8, 1977
    Date of Patent: May 29, 1979
    Assignee: Sanyo Electric Co., Ltd.
    Inventors: Shoshaku Kurome, Yoshifumi Miyazaki
  • Patent number: 4149114
    Abstract: This invention presents several meters characterized by a novel stator structure having distinct and separated energizing and exciting windings and provided with squirrel cage rotors of conventional design which are energized by induction, replacing rotors having commutator and brushes. Several species are derived in analogy to series, shunt, universal and repulsion motors, which exhibit similar characteristics, as their counterparts with commutators. As no rotating fields are considered, multipole, single phase motors and Multiphase motors are repetitions of the basic single phase two pole design.
    Type: Grant
    Filed: September 30, 1974
    Date of Patent: April 10, 1979
    Inventor: Richard Gorjan
  • Patent number: 4139790
    Abstract: A permanent magnet rotor for a permanent magnet synchronous-run induction-state motor is disclosed. The rotor has Rare Earth magnets disposed in apertures in unitary laminations and parallel to a tangent to the shaft. The magnets are magnetized outwardly so that the direct flux of the magnets is additive to the direct axis flux of the stator at no load. The rotor has a squirrel cage winding and the ends of each magnet aperture are in communication through a flux barrier space to the inner end of an adjacent conductor bar aperture of the squirrel cage winding. The unitary laminations each have an even plurality of radially directed reinforcing ribs disposed along the magnetic neutral axes. The flux barriers are wide relative to the circumferential width of the reinforcing ribs for a minimum of circumferential leakage flux. The leakage flux from one magnet radially through a rib is in opposition to the leakage flux through that rib from the adjacent magnet for substantially zero net leakage flux therein.
    Type: Grant
    Filed: August 31, 1977
    Date of Patent: February 13, 1979
    Assignee: Reliance Electric Company
    Inventor: Charles R. Steen
  • Patent number: 4114462
    Abstract: Vibratory power unit for vibrating conveyers and screens comprising an asynchronous polyphase motor, at least one pair of associated unbalanced masses disposed on the shaft of said motor, with the first mass of a pair of said unbalanced masses being rigidly fastened to said shaft and with said second mass of said pair being movably arranged relative to said first mass, means for controlling and regulating the conveying rate during conveyer operation by varying the rotational speed of said motor between predetermined minimum and maximum values, said second mass being movably outwardly by centrifugal force against the pressure of spring means, said spring means being prestressed in such a manner that said second mass is, at rotational motor speeds lower than said minimum speed, held in its initial position, and at motor speeds between said lower and upper values in positions which are radially offset with respect to the axis of said motor to an extent depending on the value of said rotational motor speed.
    Type: Grant
    Filed: May 24, 1974
    Date of Patent: September 19, 1978
    Inventor: Klaus Jurgen Grimmer
  • Patent number: 4081726
    Abstract: An electric induction motor having at least two phases and including opposed slotted stator bodies or pole pieces with each slot receiving a radially extending leg or like portion of at least one coil winding, and with the stator being preferably of an annular, segmented configurationand the rotor being a low inertia, non-magnetic, radially slotted, electrically conductive disc axially spaced from the face of the stator bodies. The motor is particularly adapted for direct drive of rapidly reversible driven members, such as washing machine agitators or the like, and is characterized by high starting torque and a relatively direct proportional relation between the applied voltage and available output torques. In use, the motor operates at varying speeds and torque as it reverses direction and accelerates to a given rotational velocity, drawing substantially constant power during use.
    Type: Grant
    Filed: January 5, 1976
    Date of Patent: March 28, 1978
    Assignee: Linear International Corporation
    Inventors: Claude Morris Brimer, Joe W. Von Brimer, deceased
  • Patent number: 4074160
    Abstract: Alternating-current, brushless, stator-controlled, asynchronous or synchronous-running, induction machines having a rotor with asymmetry in two axes electrically at right-angles, comprising two machine units coupled mechanically and electrically, to avoid the disadvantage of low-frequency currents in the mains supply experienced with single units. The coupled machine units are preferably combined in a single frame, providing right-angle electrical displacement between the two units. In one form, a single rotor is common to both stator elements. Asynchronous running is effected by extracting slip energy. Also synchronous running can be effected by d.c., as well as a.c., energizing of the stator windings. In neither mode of operation are connections to the rotor required.
    Type: Grant
    Filed: July 25, 1975
    Date of Patent: February 14, 1978
    Assignee: National Research Development Corporation
    Inventor: Alexander R. W. Broadway
  • Patent number: 4051401
    Abstract: A spherical air gap motor wherein the magnetic ring closing the stator magnetic loop has a non-cylindrical shape.
    Type: Grant
    Filed: June 1, 1976
    Date of Patent: September 27, 1977
    Inventor: William George Hayward
  • Patent number: 4045698
    Abstract: An electric motor having a rotor member and a stator member which define an air gap from about 0.001 inch to about 0.006 inch in width, the ratio of air gap width to rotor diameter being from about 0.0009 to about 0.005.
    Type: Grant
    Filed: May 3, 1976
    Date of Patent: August 30, 1977
    Inventor: Wayne J. Morrill
  • Patent number: 4011478
    Abstract: A speed sensing mechanism for a motor vehicle skid control system has ferromagnetic portions spaced around the periphery of an exciter wheel, the exciter wheel being adapted to be mounted for movement with a motor vehicle wheel whose speed is to be monitored to move the ferromagnetic portions of the exciter wheel in a plane through a station at a rate or frequency corresponding to the speed of vehicle wheel rotation. A permanent magnet is disposed within a wire sensor coil and is mounted at the station with a first pole face in closely spaced relation to the plane of movement of the ferromagnetic portions of the exciter wheel so that the reluctance of the magnetic circuit established by the permanent magnet is varied as each of the ferromagnetic elements is moved through the station, thereby to induce an electrical signal in the coil having a frequency corresponding to vehicle wheel speed.
    Type: Grant
    Filed: June 2, 1975
    Date of Patent: March 8, 1977
    Assignee: Texas Instruments Incorporated
    Inventor: Arthur L. Reenstra
  • Patent number: 4007386
    Abstract: Electric induction motors are either of the cylindrical or axial air-gap types; disadvantages of the former type, which is the more common in use, are in part overcome by the latter type, but the invention provides a new concept in electric induction motors and drive assemblies of the axial air-gap type, which eliminates the need for maintenance and substantially removes the need for skilled personnel for inspection, cleaning, modification or even installation. Induction drives according to the invention have a virtually instantaneously replaceable stator core, so that a failed stator winding can be overcome by removing it and fitting a new one, so that continued use of the electric drive can be resumed after a few minutes downtime only. Various structural arrangements for achieving this are disclosed.
    Type: Grant
    Filed: May 16, 1975
    Date of Patent: February 8, 1977
    Inventor: Romuald Zdzislaw Rustecki
  • Patent number: 4002936
    Abstract: An electric submersible pump having an electric motor forming a unit with the pump impeller and where the stator of the motor has 2 pm (p = number of pole pairs, m = number of phases) groups of coils, each group being subdivided into a plurality of coils of different width arranged symmetrically with respect to the axis of each group of coils and where the coils of each group are adapted to have different voltages applied thereto. The voltages imparted to the coils increase from the coil of smallest width to the coil of largest width by small amounts to eliminate arcing between adjacent conductors in the medium being conveyed. A portion of the liquid pumped by the impeller moves past the coils to provide cooling.The method of operating an asynchronous motor having a plurality of coils in the stator where each coil had a single turn winding comprising the steps of applying different voltages to the coils where the voltages between adjacent coils is less than that to cause arcing between adjacent coils.
    Type: Grant
    Filed: June 11, 1974
    Date of Patent: January 11, 1977
    Inventor: Nikolaus Laing
  • Patent number: 3940646
    Abstract: A single-phase induction motor provides a plurality of serially connected main winding coils and a plurality of corresponding auxiliary winding coils each spaced in quadrature from a corresponding main winding coil. Each auxiliary winding coil is energized by the current induced in a serially connected pick-up coil located within a stator slot containing the quadrature main winding coil in response to the energization of the main winding coil for providing a starting torque to the rotor. Each auxiliary coil contains a first predetermined number of turns wound in a first direction within one stator slot and a second predetermined number of turns wound in a second direction located in an adjacent stator slot for increasing the resistance-to-reactance ratio. Each pick-up coil contains approximately one-half the turns of each auxiliary coil which, in turn, has a substantially lesser number of turns than each main coil.
    Type: Grant
    Filed: March 28, 1974
    Date of Patent: February 24, 1976
    Assignee: A. O. Smith Corporation
    Inventor: John B. Buckman
  • Patent number: 3939370
    Abstract: The disclosure is of a variable speed three-phase motor with a intermediate rotor and inner rotor, where the pack of laminations of the main rotor is prolonged as an annular pack of laminations in the direction of the longitudinal axis with short-circuit rods extending over the whole length of the stator, thereby forming an annular intermediate rotor inside which the inner rotor with its short-circuit rods rotates.
    Type: Grant
    Filed: June 18, 1974
    Date of Patent: February 17, 1976
    Inventor: Arnold Muller