Patents Assigned to Maghemite Inc.
  • Patent number: 4808893
    Abstract: A procedure for stopping and starting a D.C. ferrite toroid motor so as to ensure that the rotor always rotates in the correct direction on starting. The windings in the stator are arranged in a plurality of circuits. Upon opening of the power switch to the motor, activation of one of the stator circuits only results in magnetic poles which attract the rotor poles, thereby slowing and stopping the rotor. Upon activation of the other of the stator circuits, an attractive stator pole is established ahead of a rotor pole and a repulsive stator pole is established behind the rotor pole, thereby ensuring rotation in the desired direction.
    Type: Grant
    Filed: November 6, 1986
    Date of Patent: February 28, 1989
    Assignee: Maghemite Inc.
    Inventor: Patrick E. Cavanagh
  • Patent number: 4766284
    Abstract: Reactions between solid materials to form useful products, for example, strontium ferrites, are effected by heating a primary solid feed material with a plasma gas stream to melt the primary feed material and then contacting a secondary solid feed material with the molten primary feed material and the plasma gas stream to melt the secondary feed material and enable reaction among the reactants to occur. The method of the invention simplifies the effecting of solid-solid reactions using plasma gas streams and permits the use of impure materials as the secondary feed material, strontium carbonate or strontium oxide and ferric oxide (hematite), so as to form a strontium ferrite.
    Type: Grant
    Filed: March 5, 1986
    Date of Patent: August 23, 1988
    Assignee: Maghemite Inc.
    Inventor: Patrick E. Cavanagh
  • Patent number: 4746844
    Abstract: Novel winding arrangements and control circuits for brushless direct-current motors are described. Stator windings are arranged to produce an essentially continuous torque in each winding phase from D.C. current pulses each of about one-half the duration of a two-pole cycle or rotor movement. An electronic control circuit comprises one electronic power switch for each winding group or winding phase in the stator windings. One or two D.C. current pulses are applied to the windings for each two-pole cycle of rotor movement, depending on the arrangement of the coils. CEMF voltage generated in the coils is sensed and a change in the polarity thereof is used to control switching of the D.C. current between coils.
    Type: Grant
    Filed: July 16, 1986
    Date of Patent: May 24, 1988
    Assignee: Maghemite Inc.
    Inventors: John S. MacKelvie, Eric Whiteley
  • Patent number: 4710667
    Abstract: A dynamoelectric machine which may operate in a motor mode or a generator mode is described wherein substantially the entire magnetic circuit is provided by ferrite material. In one particular embodiment, hard ferrite permanent magnet segments are mounted on a rotor plate while soft ferrite magnet segments with electrical coil windings mounted thereon are provided in a stator spaced apart from the rotor by an air gap. Other embodiments of the concept are described. Provision is made for decreasing mechanical vibration and audible noise by decreasing the magnitude of pulsations of air gap flux.
    Type: Grant
    Filed: August 11, 1986
    Date of Patent: December 1, 1987
    Assignee: Maghemite Inc.
    Inventor: Eric Whiteley
  • Patent number: 4605874
    Abstract: A dynamoelectric machine which may operate in a motor mode or a generator mode is described wherein substantially the entire magnetic circuit is provided by ferrite material. In one particular embodiment, hard ferrite permanent magnet segments are mounted on a rotor plate while soft ferrite magnet segments with electrical coil windings mounted thereon are provided in a stator spaced apart from the rotor by an air gap. Other embodiments of the concept are described.
    Type: Grant
    Filed: February 20, 1985
    Date of Patent: August 12, 1986
    Assignee: Maghemite Inc.
    Inventor: Eric Whiteley
  • Patent number: 4542361
    Abstract: Permanent magnets are used to perform useful work. The field of a first permanent magnet is diverted by electromagnetic coils to such a low value that another opposing permanent magnet can approach the first magnet without the application of undue force. The field in the first magnet is restored to act on the second magnet so as to repel it. The force which results may be harnessed to effect reciprocal or rotary motion.
    Type: Grant
    Filed: May 21, 1984
    Date of Patent: September 17, 1985
    Assignee: Maghemite Inc.
    Inventor: Patrick E. Cavanagh
  • Patent number: 4277329
    Abstract: Electrically-conducting particles may be separated from mixtures thereof containing non-conducting particles by conveying the mixture through a magnetic field oriented angularly with respect to the part of conveyance. The magnetic field induces magnetic poles in the conducting particles, causing them to deflect from the path of movement of the mixture as they attempt to move in the angular orientation of the magnetic field. The non-conducting particles are unaffected, so that a separation may be achieved. The invention is applicable to a wide variety of materials, such as ores or tailings which contain desired electrically-conducting particles, such as, iron oxide, and unwanted gangue constituents.
    Type: Grant
    Filed: August 10, 1979
    Date of Patent: July 7, 1981
    Assignee: Maghemite Inc.
    Inventor: Patrick E. Cavanagh