ELECTRIC MOTOR ADAPTED FOR BOTH STEPPING AND CONTINUOUS OPERATION

• US 3,809,990 A
• Filed: 07/27/1972
• Issued: 05/07/1974
• Est. Priority Date: 07/27/1972
• Status: Expired due to Term

• Current Assignee: Dana Corporation (Dana, Inc.)
• Original Assignee: Benjamin C. Kuo, Kenneth S. Kordik
• Inventors: Kuo, Benjamin C., Kordik, Kenneth S.
• Primary Examiner(s): Simmons, G. R.
• Application Number:
  US05/275,732
• Time in Patent Office: 649 Days
• Field of Search: 310/49 318/138,254,696,685
• US Class Current: 318/696
• CPC Class Codes: H02K 16/00 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 Class Codes: H02K 37/00 Motors with rotor rotating step by step and without interrupter or commutator driven by the rotor, e.g. stepping motors

Abstract

An electric motor adapted for operation in either a stepping mode or a continuous mode. The stator assembly of the motor includes three magnetically independent stator sections spaced along a common axis with each section forming a plurality of magnetic poles of alternating polarity around the circumference thereof, and having a plurality of teeth with the teeth of each stator section circumferentially offset from the teeth of one of the other sections by distance equal to the tooth pitch divided by the number of stator sections. The stator assembly is wound with a multi-phase winding having a separate phase wound on each stator section and connected to a common d-c. voltage source. A plurality of transistors are connected in circuit with the voltage source and each phase of the stator winding for selectively energizing each of the phases independently of the other. A rotor assembly is journalled for rotation in all the stator sections and has teeth with the same pitch as the teeth on the stator sections, and has a winding wound between the rotor teeth. A commutator is connected from the d-c. voltage source to the rotor winding for converting d-c. current from the source to a-c. current in the winding when the rotor assembly is turned. Switches connect and disconnect the voltage source from the commutator, and a plurality of gates actuate the transistors to control the energization of the various phases of the stator winding. When the motor is operated in the continuous mode, all the gates are enabled at the same time to actuate all the transistors to continuously energize all the phases of the stator winding so as to effect continuous rotation of the rotor, while the commutator is connected to the voltage source. In the stepping mode, a pulse generator produces pulses which are fed to a counter for producing output signals sequentially on a series of output lines for enabling the gates in sequence to turn on the transistors in sequence, thereby energizing the various phases of the stator winding in sequence to effect stepping rotation of the rotor assembly in synchronism with the pulses from the pulse generator.

Claims

1. An electric motor adapted for both stepping and continuous operation, said motor comprising the combination of:

a. cooperating stator and rotor assemblies forming an air gap therebetween, b. a multi-phase winding on said stator assembly, c. a winding on said rotor assembly and fed by commutating means, d. step mode control means including means for de-energizing said commutator-fed rotor winding and energizing the multiple phases of said stator winding in sequence to effect stepping rotation of the rotoR assembly in synchronism with the sequential energization of the multiple phases of said stator winding, e. continuous mode control means including means for producing a constant magnetic field from said stator assembly in said air gap and means for continuously energizing said commutator-fed rotor winding to effect continuous rotation of the rotor assembly, and f. mode selection means for selectively enabling said step mode control means or said continuous mode control means.

2. An electric motor as set forth in claim 1 wherein said means for continuously energizing said rotor winding includes a d-c. voltage source and a commutator connected between said source and said rotor winding for converting d-c. current from said source to a-c. current in said rotor winding in response to rotation of said rotor assembly.

3. An electric motor as set forth in claim 1 wherein the stator assembly includes a plurality of magnetic poles of alternating polarity disposed around the rotor assembly.

4. An electric motor as set forth in claim 1 wherein the stator assembly includes a plurality of magnetically independent toothed stator sections spaced axially along the rotor assembly with the teeth in each stator section circumferentially offset from the teeth in each of the other stator sections, each of said stator sections being connected to one of the phases of said multi-phase winding, and said rotor assembly is also toothed whereby sequential energiztion of the toothed stator sections effects stepping rotational movement of the rotor assembly.

5. An electric motor as set forth in claim 4 wherein the circumferential offset of the teeth of said stator sections is equal to the pitch of the rotor teeth divided by the number of stator sections.

6. An eletric motor as set forth in claim 4 wherein each stator section is wound to produce a plurality of magnetic poles of alternating polarity around the rotor assembly in response to energization of the stator winding.

7. An electric motor as set forth in claim 4 wherein each stator section includes permanent magnets for producing a plurality of magnetic poles of alternating polarity around the rotor assembly.

8. An electric motor as set forth in claim 4 which includes at least three of said stator sections.

9. An electric motor as set forth in claim 4 wherein the teeth of said rotor and stator assemblies have the same pitch.

10. An electric motor as set forth in claim 4 wherein each stator section has four pole members equally spaced around the circumference of the stator, each of said pole members forming a plurality of stator teeth, and the stator winding is wound around each of said pole members so that energization of said winding magnetizes each adjacent pair of said pole members with opposite polarities.

11. An electric motor as set forth in claim 1 wherein said means for energizing the multiple phases of said stator winding in sequence includes a pulse generator for producing pulses and circuit means responsive to said pulses for sequentially energizing the separate phases of said multi-phase winding.

12. An electric motor as set forth in claim 11 wherein said circuit means includes a voltage source, a plurality of electronic switching means connected from said source to said multi-phase winding, and means for supplying said pulses to said plurality of switching means in sequence, for rendering said switching means conductive to sequentially energize the separate phases of said multi-phase winding.

13. An electric motor as set forth in claim 12 wherein each of said electronic switching means comprises a transistor.

14. An electric motor as set forth in claim 12 wherein said means for suplying said pulses to said switching means in sequence comprises an up-down counter connected to said pulse generator.

15. An electric motor as set forth in claim 1 wherein said means for producing a constant magnetic field in said air gap comprises means for simultaneously energizing all phases of said statOr winding with a constant d-c. signal.

16. An electric motor as set forth in claim 1 wherein said means for producing a constant magnetic field comprises permanent magnetic portions of said stator assembly.

17. An electric motor adapted for both stepping and continuous operation, said motor comprising the combination of a stator assembly including at least three magnetically independent stator sections spaced along a common axis with each section forming a plurality of magnetic poles of alternating polarity around the circumference thereof and having a plurality of teeth with the teeth of each section circumferentially offset from the teeth of one of the other sections by a distance equal to the tooth pitch divided by the number of stator sections;

a multi-phase stator winding having a separate phase wound on each of said stator sections;

a d-c. voltage source;

a plurality of electronic switching means connected in circuit with said source and each phase of said stator winding for selectively energizing each of said phases indpendently of the others;

a magnetically permeable rotor assembly journalled for rotation within all said stator sections and having teeth with the same pitch as the teeth on said stator section, said rotor and stator assemblies forming an air gap therebetween;

a winding wound on said rotor assembly between the teeth thereof;

a commutator connected from said source to said rotor winding for converting d-c. current from said source to a-c. current in said winding in response to rotation of the rotor assembly;

switching means for connecting and disconnecting said source to and from said commutator;

a plurality of gating means for actuating said electronic switching means to control the energization of the various phases of said stator winding;

means for enabling all said gating means at the same time to actuate all said electronic switching means to continuously energize all the phases of said stator winding with a constant d-c. signal to produce a constant magnetic field in said air gap to effect continuous rotation of the rotor assembly when said commutator is connected to said source to continuously energize said rotor winding;

pulse generating means for producing pulses to control stepping movement of the rotor assembly; and

counting means responsive to said pulses for producing output signals sequentially on a series of output lines for enabling said plurality of gating means in sequence to actuate said electronic switching means in sequence, thereby energizing the various phases of said stator winding in sequence to effect stepping rotation of the rotor assembly in synchronism with said pulses when said commutator is disconnected from said source to de-energize said rotor winding.