Electric motor and magnetic gear

Patent metadata

Field	Value
Publication number	US-9438096-B2
Application number	US-201414315448-A
Country	US
Kind code	B2
Filing date	Jun 26, 2014
Priority date	Jul 30, 2013
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

An electric motor that can be used in driving a compressor and that incorporates a magnetic gear. The motor has high and low speed stators mounted within a motor casing side-by-side that drive coaxial low and high speed rotors also mounted within the motor casing for rotation and within the high and low speed stators. The high and low speed stators produce rotating magnetic fields that rotate in opposite directions to drive the rotors under application of a multiphase alternating current. The low speed rotor has a set of ferrous pieces, rotating with the low speed rotor and mounted thereon between the high speed rotor and the high speed stator. The ferrous pieces produce a magnetic gearing effect to drive the high speed rotor at a higher speed than the low speed rotor and in an opposite direction to the low speed rotor.

First claim

What is claimed is:

1. An electric motor comprising:
a motor casing;
a high speed stator and a low speed stator mounted within the motor casing side-by-side;
the high speed stator and the low speed stator each including winding systems having separate windings and electrical connections between the separate windings configured such that the separate windings are able to be separately exited by out-of-phase electrical currents generated by a multiphase alternating current source and thereby to produce magnetic fields emanating from stator pole pairs of the separate windings rotating around each of the high speed stator and the low speed stator in opposite directions when the windings are connected to the multiphase alternating current source;
a low speed rotor mounted within the motor casing for rotation, coaxial to and surrounded by the high speed stator and the low speed stator, the low speed rotor having a first set of pole pieces mounted at one end thereof and opposite to the low speed stator such that the magnetic fields produced by the low speed stator are able to induce a rotation of the low speed rotor in a rotation direction of the of the magnetic fields produced by the low speed stator and a set of ferrous pieces mounted at the other end and opposite to the high speed stator and separated from one another by non-ferrous regions of the low speed stator so as to be able to conduct the magnetic fields produced by the high speed stator;
a high speed rotor mounted within the motor casing for rotation coaxial to the low speed rotor and telescoped within the low speed rotor, the high speed rotor having a second set of pole pieces opposite to the ferrous pieces of the low speed rotor and the high speed stator; and
the set of ferrous pieces of the low speed rotor present in a number equal to a sum of the stator pole pairs of the high speed stator and rotor pole pairs provided by the pole pieces of the high speed rotor so that motion of the ferrous pieces produced by the rotation of the low speed rotor in turn produces a gearing effect in which the high speed rotor rotates at a higher speed than the magnetic fields produced by the high speed stator and in an opposite direction thereto.

2. The electric motor of claim 1 , wherein the higher speed of the high speed rotor is given by the equation [60(f)(1+(P1:P2))(P1:P3)]/P1 for an even number of ferrous pieces or the amount derived from the foregoing equation plus 60(f)/P2 for an odd number of ferrous pieces;
where “f” is the frequency of the multiphase alternating current source; P1 is the number of pole pairs on the high speed stator; P2 is the number of pole pairs on the low speed stator and P3 is the number of pole pairs on the high speed rotor.

3. The electric motor of claim 1 , wherein the multiphase alternating current source is a three phase alternating current source.

4. The electric motor of claim 3 , wherein each of the first and second sets of the pole pieces are formed by permanent magnet materials.

5. The electric motor of claim 4 , wherein windings of the high speed stator and the low speed stator are wound in opposite directions and are configured to share the multiphase alternating current source.

6. The electric motor of claim 5 , wherein each of the high speed stator and the low speed stator are of laminated construction having inwardly directed prongs supporting the windings.

7. The electric motor of claim 5 , wherein the low speed rotor is formed of a non-ferrous material and is of cylindrical configuration and the low speed rotor has cavities within which the first set of pole pieces and the ferrous pieces are mounted.

8. The electric motor of claim 7 , wherein the high speed stator has three pole pairs, the high speed rotor has one rotor pole pair and there are four ferrous pieces on the low speed rotor.

9. The electric motor of claim 1 , wherein windings of the high speed stator and the low speed stator are wound in opposite directions and are configured to share the multiphase alternating current source.

10. An electric motor and compressor assembly comprising:
a motor casing;
a high speed stator and a low speed stator mounted within the motor casing side-by-side;
the high speed stator and the low speed stator each including winding systems having separate windings and electrical connections between the separate windings configured such that the separate windings are able to be separately exited by out-of-phase electrical currents generated by a multiphase alternating current source and thereby to produce magnetic fields emanating from stator pole pairs of the separate windings rotating around each of the high speed stator and the low speed stator in opposite directions when the windings are connected to the multiphase alternating current source;
a low speed rotor mounted within the motor casing for rotation, coaxial to and surrounded by the high speed stator and the low speed stator, the low speed rotor having a first set of pole pieces mounted at one end thereof and opposite to the low speed stator such that the magnetic fields produced by the low speed stator are able to induce a rotation of the low speed rotor in a rotation direction of the of the magnetic fields produced by the low speed stator and a set of ferrous pieces mounted at the other end and opposite to the high speed stator and separated from one another by non-ferrous regions of the low speed stator so as to be able to conduct the magnetic fields produced by the high speed stator;
a high speed rotor mounted within the motor casing for rotation coaxial to the low speed rotor and telescoped within the low speed rotor, the high speed rotor having a second set of pole pieces opposite to the ferrous pieces of the low speed rotor and the high speed stator; and
the set of ferrous pieces of the low speed rotor present in a number equal to a sum of the stator pole pairs of the high speed stator and rotor pole pairs provided by the pole pieces of the high speed rotor so that motion of the ferrous pieces produced by the rotation of the low speed rotor in turn produces a gearing effect in which the high speed rotor rotates at a higher speed than the magnetic fields produced by the high speed stator and in an opposite direction theretopole pairs; and
a compressor directly coupled to the high speed rotor to compress a fluid within the process plant.

11. The electric motor and compressor assembly of claim 10 , wherein the higher speed of the high speed rotor is given by the equation [60(f)(1+(P1:P2))(P1:P3)]/P1 for an even number of ferrous pieces or the amount derived from the foregoing equation plus 60(f)/P2 for an odd number of ferrous pieces; where “f” is the frequency of the multiphase alternating current source; P1 is the number of pole pairs on the high speed stator; P2 is the number of pole pairs on the low speed stator and P3 is the number of pole pairs on the high speed rotor.

12. The electric motor and compressor assembly of claim 11 , wherein the compressor is a centrifugal compressor.

13. The electric motor and compressor assembly of claim 12 , wherein the compressor is configured to compress air.

14. A magnetic gear comprising:
a casing;
a stator mounted within the casing and including a winding system having separate windings and electrical connections between the separate windings configured such that the separate windings are able to be separately exited by out-of-phase electrical currents generated by a multiphase alternating current source and thereby to produce magnetic fields emanating from stator pole pairs of the separate windings rotating around the stator when the windings are connected to

Assignees

• Abbott Timothy D
• Praxair Technology Inc

Inventors

• Abbott Timothy D

Classifications

• H02K49/102

  Magnetic gearings, i.e. assembly of gears, linear or rotary, by which motion is magnetically transferred without physical contact (magnetized gearings with physical contact F16H13/12, F16H49/005) · CPC title

• H02K7/11

  with dynamo-electric clutches · CPC title

• H02K16/04

  Machines with one rotor and two stators · CPC title

• H02K16/00 Primary

  Machines with more than one rotor or stator {(machines for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts H02K51/00; permanent magnet machines with multiple rotors or stators relatively rotated for vectorially combining the excitation fields or the armature voltages H02K21/029)} · CPC title

• F04D25/06

  the pump being electrically driven (F04D25/08 takes precedence) · CPC title