ROTARY STEPPING MOTOR WITH ECCENTRIC ROTOR

• US 3,560,774 A
• Filed: 12/16/1968
• Issued: 02/02/1971
• Est. Priority Date: 12/16/1968
• Status: Expired due to Term

• Current Assignee: Raymond R. Reeves
• Original Assignee: Raymond R. Reeves
• Inventors: Reeves, Raymond R.
• Application Number:
  US04/783,789
• Time in Patent Office: 778 Days
• US Class Current: 310/82
• CPC Class Codes: G06K 13/20 Details
• CPC Class Codes: H02K 41/06 Rolling motors, i.e. motors having the rotor axis parallel to the stator axis and following a circular path as the rotor rolls around the inside or outside of the stator ; Nutating motors, i.e. having the rotor axis parallel to the stator axis inclined with respect to the stator axis and performing a nutational movement as the rotor rolls on the stator

Abstract

An electric stepping motor comprising a stator with three or more circumferentially displaced poles and provided with a rotor (inside or outside) which is arranged to transmit angular drive in discrete steps, the rotor moving eccentrically in relation to the axis of the stator. Both the rotor and stator may carry cooperating gears. Permanent magnet detents are provided on the stator. The drive coupling may be a slide arrangement, a flexible bellows, or an eccentric cam. The control circuitry includes a pulsing arrangement, ring counter, inductive pickoffs, and a coincidence detector.

Claims

1. An electric stepping motor comprising a rigid rotor, a stator including field generating means which provide a number of poles circumferentially displaced around an axis and adapted for deflecting the rotor to produce an annular movement thereof in discrete steps in relation to said axis, means for stopping the rotor at each pole, said rotor having an eccentric movement and rolling in relation to said stator, an output shaft which revolves about a fixed axis coaxial with the first said axis, and coupling means connecting said output shaft to said rotor for converting said eccentric movement of said rotor to rotational movement of said output shaft about said fixed axis in the same direction and with the same angular displacement as the rotor about its own axis.

2. An electric stepping motor as claimed in claim 1 in which the rotor is cylindrical, is positioned within and rolls around within a cylindrical bore in the stator.

3. An electric stepping motor as claimed in claim 2 in which the stator carries at least one internal toothed gear and the rotor carries at least one intermeshing external gear meshed with the first said gear.

4. An electric stepping motor as claimed in claim 3 in which said at least one internal gear and said at least one external gear comprise intermeshing gears provided at each axially displaced end of the stator and rotor.

5. An electric stepping motor as claimed in claim 1 in which the stator is cylindrical and the rotor has an internal bore, is positioned about and rolls around the external surface of the stator.

6. An electric stepping motor as claimed in claim 5 in which intermeshing gears are provided between the stator and rotor.

7. An electric stepping motor as claimed in claim 6 in which said gears are provided by a series of radially projecting pins on the stator which engage a series of circumferentially spaced openings in the rotor.

8. An electric stepping motor as claimed in claim 1 in which the coupling means comprises an intermediate drive member connected to one end of the rotor through a first diametrically extending slide, and the drive member is connected to a driven shaft through a second diametrically extending slide extending in a direction normal to the first.

9. An electric stepping motor as claimed in claim 1 in which the coupling means comprise a flexible bellows.

10. An electric stepping motor as claimed in claim 1 in which the coupling means comprise a shaft which is coaxial with the axis of the stator through an eccentric cam carried in a bearing in the rotor, and which is driven by the rotor.

11. An electric stepping motor as claimed in claim 10 in which the drive shaft extends axially through the rotor from one end to the other.

12. An electric stepping motor as claimed in claim 11 in which each end of the drive shaft is carried in bearings in a support assembly.

13. An electric stepping motor as claimed in claim 11 in which means including a permanent magnet system are provided for holding the rotor in its stepped positions.

14. An electric stepping motor as claimed in claim 13 in which each pole is provided with an associated permanent magnet which is strong enough to hold the rotor in position when stationary but the attraction force of which is overcome when the appropriate next pole is energized.

15. An electric stepping motor as claimed in claim 14 including means for energizing each permanent magnet with a DC voltage at the same time as its associated pole is energized to increase the hold torque of the permanent magnet system.

16. An electric stepping motor as claimed in claim 1 including means for providing a signal indicative that the rotor has stepped.

17. An electric stepping motor as claimed in claim 16 in which the means for providing a signal comprise an inductive pickoff arranged at each pole.