Cambridge Thermionic Corporation

Joseph Lyman

Frank Lyman

Improved apparatus is disclosed for use in a magnetic suspension system for developing signals representative of the rate of displacement of a magnetically suspended body along one or more axes thereof for use in applying forces to the body to restore it to a desired stable position. Specifically there are provided a plurality of thin, closely-spaced discs of permanent magnet material affixed to the body and a plurality of conductive windings respectively cooperating with the magnetic fields produced by said magnets, pairs of said windings being interconnected so that currents induced therein by the fields of the magnets tend to reinforce each other and so that currents induced therein by stray fields tend to cancel. The resultant currents induced in the windings are representative of rate of displacement of the suspended body and may be combined with separately derived signals representative of displacement of the body for use in applying forces to the body to restore it to its desired stable position. By suitably arranging the permanent magnets and their cooperating windings, signals may be developed representative of rates of displacement along several different axes so as to permit complete control over all possible displacements of the suspended body. In addition, in certain embodiments of the invention, there may be provided means for deriving from the rate-representative signals, signals representative of acceleration of the suspended body which also may be used to control the application to the body of forces to restore it to its desired stable position.

Rate responsive control for magnetic suspension system

A magnetically suspended rotor system is provided capable of operating at rotational speeds of 100,000 rpm or greater. The system comprises a rotor assembly and electric motor means for producing rotation of the assembly about an axis thereof. Electromagnetic means disposed near one end of the rotor is energized to exert an attractive force on the rotor to support it and preferably cooperates with permanent magnet means affixed to the rotor assembly near one (the upper) end thereof. An additional permanent magnet affixed to the rotor near the opposite (lower) end thereof cooperates with another permanent magnet disposed in juxtaposition thereto to exert an attractive force on the rotor tending to oppose the force exerted by electromagnetic means and produces a radial constraining force on the rotor tending to center the lower end of the rotor assembly. A conductive element is interposed between the lower end of the rotor assembly and the latter permanent magnet which cooperates with the magnetic field produced by the permanent magnet in the lower end of the rotor assembly to inhibit nutation of the lower end of the rotor assembly by virtue of eddy currents induced therein. Means are provided responsive to displacement of the rotor in the direction of its axis of rotation for controlling the currents supplied to the electromagnetic means so as to tend to restore the rotor to its position prior to such displacement. The rotor may be driven by a motor utilizing regenerative commutation of the sort disclosed in co-pending application Ser. No. 695,507, filed June 11, 1976. The system disclosed makes possible the achievement of unusually high rotational speeds by minimizing or eliminating undesired resonances in the rotor assembly.

High speed rotor system

An electric motor system comprising a rotor including permanent magnets providing a plurality of correspondingly directed magnetic poles angularly displaced around said rotor, a stator comprising first and second windings adapted to cooperate with the poles of said rotor, each of said windings having transversely disposed conductive portions for intercepting the magnetic fields of said poles during rotation of said rotor, and an amplifier having its input coupled to said first winding so as to be energized by alternating voltage induced in said first winding during rotation of said rotor, and having its output coupled to said second winding to supply alternating current therethrough in synchronism with the interception of the magnetic fields of said poles by the transverse portions of said second winding. A motor system in accordance with the invention is capable of achieving extremely high speeds of rotation particularly when the rotor structure is suspended by means of magnetic bearings well known in the art. Provision for limiting the speed of operation of the motor may be made comprising a low-pass filter included in the feedback path from the first winding to the second winding. Also provision may be made for initiating rotation of the rotor, which may comprise Hall effect sensors disposed adjacent to the transverse portions of the first winding, the outputs of which are combined and supplied to the input of the amplifier to cause alternating current to be supplied to the second winding to initiate rotation of the rotor.

Electric motor system

A method is described for producing permanent magnets, in accordance with which magnetic material in finely divided or powdered form, comprising an alloy of a rare earth metal and cobalt, is first premagnetized by subjecting it to a high-intensity magnetic field to magnetize the individual particles thereof, the particles are then introduced into a hardenable resinous material and caused to be distributed substantially uniformly throughout at least a region of said resinous material. While said particles are being introduced into and distributed throughout said resinous material, they are subjected to a magnetic field to align them magnetically. The resinous material is then hardened to form a body thereof in which said particles are maintained in magnetic alignment to form an effective permanent magnet structure. In preferred forms of the invention, fibrous material and/or fiberglass cloth or mat may be embedded in the matrix to enhance its strength. In addition, an auxiliary magnetizing coil may be embedded in the matrix for modulating the effective magnetic field of the permanent magnet on a temporary basis. Practice of the method permits the production of superior permanent magnets which may be of relatively large size compared to those producible in accordance with the methods of the prior art and whose resistivity may be controlled to adapt them for various applications such as use in magnetic bearings.

Spinning mold method for making permanent magnets

Rotor balancing apparatus and a system comprising balance probes for measuring unbalance at the ends of a magnetically suspended rotor are disclosed. Each balance probe comprises a photocell which is located in relationship to the magnetically suspended rotor such that unbalance of the rotor changes the amount of light recorded by each photocell. The signal from each photocell is electrically amplified and displayed by a suitable device, such as an oscilloscope.

Growing community of inventors

Kennebunk, ME, United States of America

Joseph Lyman