US3803430A - Miniature motor - Google Patents

Miniature motor Download PDF

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Publication number
US3803430A
US3803430A US00304885A US30488572A US3803430A US 3803430 A US3803430 A US 3803430A US 00304885 A US00304885 A US 00304885A US 30488572 A US30488572 A US 30488572A US 3803430 A US3803430 A US 3803430A
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US
United States
Prior art keywords
disposed
rotor
ellipse
bobbin
stator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00304885A
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English (en)
Inventor
H Costa
V Foster
C Thornton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Motorola Solutions Inc
Original Assignee
Motorola Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Motorola Inc filed Critical Motorola Inc
Priority to US00304885A priority Critical patent/US3803430A/en
Priority to DE7332063U priority patent/DE7332063U/de
Priority to DE19732344502 priority patent/DE2344502A1/de
Priority to JP48101260A priority patent/JPS4995117A/ja
Priority to FR7333311A priority patent/FR2205768A1/fr
Priority to CH1328173A priority patent/CH610474B5/xx
Priority to CH1328173D priority patent/CH1328173A4/xx
Priority to SU731968215A priority patent/SU625644A3/ru
Application granted granted Critical
Publication of US3803430A publication Critical patent/US3803430A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
    • H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
    • H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C3/00—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means
    • G04C3/16—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means incorporating an electro-dynamic continuously rotating motor

Definitions

  • a slightly elliptical ring yoke of high permeability and low remanence surrounds and is bonded to the bobbin, the minor axis of the ellipse being at a slight angle to the normal of axis of the field created by the windings to create poles for stopping the rotor at a predetermined position.
  • the major axis of the ellipse is only slightly larger than the minor axis to keep the starting torque requirements low, thereby preventing increase in power consumption.
  • This invention relates to pulse operated miniature electric motors, more particularly to such miniature motors having good starting torque and low power cnsumption for watch movements and it is an object of the invention to provide improved miniature motors of this nature.
  • Miniature watch motors are known to the art and most, if not all, of them present some problems of ease of assembly, disassembly, efficiency, and torque.
  • This application provides efficient and simple solutions for these problems and presents a motor which is an integral unit separate from the watch requiring no assembly into the watch movement and no need for wiring.
  • the motor can be plugged into the printed circuit or other operating components of the watch without any separate electrical connections.
  • the motor is positively located in the watch movement and provisions are made for several different methods of securing or mounting it in place.
  • a miniature motor for a timepiece comprising: a non-magnetic stator having a central cylindrical cavity of a predetermined diameter and a predetermined longitudinal dimension; two' non-magnetic, relatively rigid disk closures attached at their peripheries to said stator for closing said cylindrical cavity to define a chamber and for rigidifying the assembly of said disks and stator;
  • the minor axis of the ellipse is at an angle of 20-30 to the normal of the field direction and the excess in length of the major axis over the minor axis is about two-three thousandths of an inch.
  • FIG. 1 is a perspective view on an enlarged scale somewhat fragmentary and with a section cut away of a motor according to the invention
  • FIG. 2 is an elevational view on a different scale taken substantially in the direction of the arrows 2--2 of FIG. 1', I
  • FIG. 3 is an elevational view taken substantially in the direction of the arrows 33 of FIG. 2;
  • FIG. 4 is a plan view with a cut out portion of one componentof the invention.
  • FIG. 5 is an elevational view taken substantially in the direction of arrows 5-5 of FIG. 1;
  • FIG. 6 is a side view with a section broken out taken substantially in the direction of arrows 6-6 of FIG. 5;
  • FIG. 7 is a diagrammatic view illustrating certain positions of the components in the functioning circuit.
  • the invention is shown as comprising a motor 10 including a stator 11 and a rotor member l2.
  • the rotor member 12 comprises a rotor 19 which may be in the form of a disk and a shaft 21 attached to the center of the rotor 19 as by some adhesive, for example an epoxy.
  • the rotating member 19 may be formed of any well known high permeability, high magnetic strength magnetic alloys such for example as samarium cobalt and is magnetized such that north and south magnetic poles exist on opposite ends of a particular diameter. In some instances it may be convenient to use an ordinary bar magnet as compared with a disk member.
  • the motor frame member or bobbin 14, also shown in FIGS. 4, 5 and 6 comprises a one piece molded construction according-to a preferred form of the invention.
  • the material may be nylon, polyvinylchloride or any other synthetic material having sufficient dimensional stability and rigidity for the intended purposes.
  • the material must be non-magnetic and in appropriate instances may also be formed of brass or aluminum, for example, although these metals would have to be annodized to produce an insulating surface so as to not risk short circuiting the windings which are ultimately disposed on the bobbin.
  • the bobbin 14 is essentially a cylindrical piece having a central cylindrical cavity 22 therein within which the rotor 19 is ultimately received, there being sufficient clearance between the walls of the cavity 22 and the surfaces of the rotor 19 for this purpose.
  • transverse grooves 23 and 24 (FIG. 6) are formed and correspondingly on the other side of the center of the bobbin transverse grooves 25 and 26 are formed.
  • longitudinal grooves 27 and 28 are formed and on the other side of the bobbin, longitudinal grooves 29 and 31 are formed.
  • the grooves 23,24 and 26,28 form one winding slot into which the winding is wound or disposed, and the grooves 25,26 and 29,31 form another-winding slot into which the winding 16 is wound or disposed.
  • the inner surfaces or bottoms 68,69 and 71,72 of the grooves 23 and 24, respectively, are parallel to each other as may be seen best in FIG. 6 but the interior surfaces or bottoms of the grooves 27 and 28, as shown for example, by lines 32 and 33 respectively in FIG. 5 are at an angle to each other and are in effect tangent to the cylindrical surface of the cavity 22.
  • the angular disposition of the bottoms 27 and 28 enables more turns of wire to be disposed in the winding groove as compared with a winding groove wherein the bottoms 27 and 28 were parallel to each other. This may be observed in FIG. 2 by noting the darker cross hatched portion as compared with lighter cross hatched portion 30.
  • the angular bottoms 27 and 28 enable the winding disposed in the grooves to be closer to the cylindrical wall of cavity 22 and thus closer to the surface of the magnetic rotor 19 which will be disposed therein. A more efficient magnetic circuit is thereby achieved.
  • the motor is enabled to develop a higher torque level or more power output for the same power input.
  • the grooves 29 and 31 have angularly disposed bottom surfaces as shown by the lines 34 and 35, respectively, and the winding groove formed by the slots 25,26 and 29,31 will receive more turns for the same stated reasons.
  • the end of the cylindrical cavity 22 terminates in circular grooves 36 and 37 which are adapted to receive, respectively, the flanges 38 and 39 of the bearing memsupported in a very stable and accurate manner.
  • the bearing members 17 and 18 may be formed of any suitably hard non-magnetic and dimensionally stable material.
  • One type of such material which has been found to be satisfactory is the alloy beryllium copper.
  • the bearing flanges 59 and 61 made of beryllium copper may run without lubrication as is well understood although lubrication of course may be provided.
  • the rotor 19 may be first assembled to the shaft 2l. Thereafter the rotor and shaft are disposed in the cavity 22 of the bobbin or frame 14. This is followed by disposing the flanges S9 and 61 of the bearing members 17 and 18 over the appropriate ends of the shaft 21 and the outer peripheries of the large diameter flanges 38 and 39 in the respective grooves 36 and 37 at the ends of the cavity 22. While in this position beads62 of synthetic material which may be of the same nature as that of the bobbin itself are formed over the outer peripheries of the flange members 38 and 39 as by the application of a heated tool. Beads 62 are formed in association with the surfaces of the grooves formed inwardly of the segmentshaped members 41 and 42 as may be seen best in bers 17 and 18, as will be more particularly described.
  • the enlarged ends 49 and 51 of the connecting pins 52 and 53 are press fitted into holes 54 and 55 in the segment members 41 and 42 respectively. Holes 56 and 57 are formed, respectively, in the boss-like members 43 and 44 for receiving attaching screws in the event that such be desired.
  • the bearing member 17 includes a sleeve portion 58 and a large diameter radially extending flange 38 at right angles thereto at one end. At the other end a smaller flange 59 exists which includes the actual bearing surface centrally thereof for receiving one end of the shaft 21. Similarly the bearing member 18 includes a large diameter radially extending flange 39 projecting at right angles to a sleeve portion 60. At the other end FIG. 1. The flange members 38 and 39 are thus firmly bonded to the bobbin 14 and form therewith a relatively rigid structure which accurately and firmly holds the shaft 21 in the proper position.
  • the windings 15 and 16 are wound in the appropriate grooves.
  • the windings, or coils, 15 and 16 are wound in the grooves described along the angular surfaces 32, 33, 34 and 35 under ordinary tension for wire of the size as used here which for example may be No. 55 ASW. 156 feet in total comprising about 2,200 turns in each of coils 15 and 16 are'wound as described and the resistance of the windings may be about 5.6K ohms.
  • the winding tension results in the inner surface of the, cylindrical cavity 22 firmly engaging the outer edges of the bearing flanges 38 and 39 thereby forming a relatively rigid and in effect a monolithic structure.
  • the windings being disposed on the outside of the bearing flange's38 and 39 thus provides a significant portion of the strength of the unit.
  • the coils 15 and 16 are connected by a run 63 of wire and the ends 64 and 65 of the coils are disposed across and in the grooves 66 and 67 in the ends 49 and 51 of the connecting pins 52 and 53.
  • the grooves 36 and 37 (FIG. 6) terminating the end of the cylindrical cavity 22 are disposed inwardly of the surfaces 68 and 69, 71 and 72, which form the inward surfaces of the grooves receiving the windings. Accordingly it will be evident that the innermost layer of the windings 15 and 16 are disposed slightly away from the surfaces of the bearing flanges 38 and 39 thereby avoiding the possibility of short circuits.
  • the ring yoke 13 Surrounding the assembly of the rotor, bobbin and windings is the ring yoke 13.
  • the ring yoke is in the form of a shell or annulus having a longitudinal, or axial, dimension equal to or slightly greater than the longitudinal dimension of the bobbin 14.
  • the inner diameter of the ring 1 1 is just slightly larger than the diameter of the bobbin 14 so that the ring may be received thereover in very close fitting relationship.
  • the slots 45 and 46 in the outer periphery of the bobbin 13 are utilized to receive a cement such as for example as an epoxy for tightly cementing the ring yoke 11 to the bobbin l4. Thereby additional rigidity and strength are imparted to the motor as a whole.
  • the ring yoke 11 is not a precise circle but differs therefrom slightly and actually is in the form of an ellipse. Reference is made to FIGS. 2 and 7 in this connection.
  • FIG. 2 the actual dimensions of one specific form of motor are shown.
  • the major axis of the ellipse is shown to be 0.2474 inches while the minor axis is shown to be 0.2444 inches.
  • the minor axis is about three thousandths of an inch less than the major axis.
  • the minor axis of the ellipse should be between. two thousandths and three thousandths of an inch less than the major axis.
  • the elliptical shape of the ring yoke 13 provides for poles at the ends of the minor axis as may be seen in FIG. 7, and determines the stationary position of the rotor 12.
  • positive and negative pulses in succession are applied to the windings l5 and 16 and provide a magnetic field in the direction of the arrow 73 in FIG. 7.
  • the application of each voltage pulse causes the rotor to step, rotate so to speak, 180 degrees thereby coming opposite the poles determined by the minor axis of the ellipse.
  • the rotor becomes stationary at this point.
  • the application of the next pulse again causes the rotor to step one-half of a revolution, and again it comes to rest at the poles determined by the minor axiso-f the ellipse.
  • the difference between the major and minor axes of the ellipse is small in order to create, on the one hand, poles so that the rotor comes to rest at the same point after each energization. On the other hand the difference'cannot be too great, or the power required to break the rotor loose for the next succeeding half revolution becomes too large. Appropriate choice of the difference keeps the power consumed by the motor.
  • the elliptical cross section is required to provide poles for stopping the rotor and the difference in dimensions must be smaller in order to prevent excessive torque being required.
  • the major axes 75 of the ellipse is disposed at an angle shown clockwise in FIG. 7 with respect to the axis 73 of the field created by the windings.
  • the minor axis 74 on which the north and south poles of the ring yoke 13 lie is therefore at the same angle to the normal 76 to the direction of field 73.
  • the rotor 12 stops with its north-south axis always at a slight angle to the normal 76 of the direction of field 73 and enables the starting torque to be applied to the same direction at each application of a positive or negative pulse. Accordingly the motor always runs in the same direction.
  • the angle a between the minor axis 74 and the normal 76 is in the vicinity of 20 in the practical case described.
  • the ring yoke 13 should be of any high permeability low remanence material such as that available under the trade name of I-Iypernic.
  • the rotor 19 may be approximately 20' percent larger in diameter than is possible in constructions where the coil shape is parallel sided and of comparable diameter. Higher torque level, or more power output, for the same electrical input is achieved.
  • the recesses .36and 37 illustrated in FIGS. 1 and 6 provide mounting space for the wide flange bearing 38 and 39, allowing for extremely accurate alignment and positive centering of the rotor shaft to the motor frame.
  • the bearing flanges also serve the purpose of entirely enclosing the rotating parts and preventing the wire winding from protruding into the rotor cavity. Also, being a close fit in their respective seats they impart a rigidity to the motor frame impossible to achieve with the molded plastic bobbin itself, thus preventing distortion due to the pressure of the many turns of tension wire wound on it.
  • the method of locking the two bearing flanges in place by hot pressing a head of plastic or synthetic material over them provides a rigid mounting and positive end play positioning without any possibility of coming loose or loosening alignment.
  • the bearings and frame become, in effect, one solid piece.
  • the bearing surfaces themselves are an integral part of the whole bearing assembly and are spaced as far apart as possible for positive alignment and reduction of radial movement at the pinion end.
  • Each bearing as may be seen, is both radial and thrust, thereby eliminating the need for additional thrust bearings.
  • the bearing 59 extends beyond the plane of the base of the motor as may be seen in FIG. 3, and its outside diameter is held to very tight concentricity and size tolerances. This provides a boss by which the motor can be accurately located in the watch movement by simply inserting the boss into a properly located hole in the watch movement.
  • the ends of the windings 64 and 65 are disposed across the grooves 66 and 67 in the end lugs 49 and 51 of the connecting pins 52 and 53.
  • a blob of solder may be disposed over the winding in the grooves 66 and 67 for firmly holding the ends of the coils in place.
  • the ends of the wires 64 and 65 may be held as shown with a dab of cement 77 and 78 until the actual soldering operation is performed whereafter the blob of cement and the attached wire end are removed.
  • the ring yoke 13 need not have any apertures or perturbations for creating any bias, or poles, for holding the position of the-rotor but this effect is achieved by having a solid ring as shown but in elliptical form rather than circular.
  • the diameter of the cavity 22 was 0.128 inches.
  • the longitudinal dimension of the cavity 22 between flanges 38 and 39 was 0.040 inches, and the diameter of the rotor 12 was 0.117 inches.
  • the diameter of the flanges 38 and 39 was 0.1365 inches and the thickness of the flanges was 0.0055 inches. It will be understood of course that small tolerances are available in each of these dimensions as will be clear to those skilled in the an. Other dimensions of course may be used for particular constructions of motors to meet the particular conditions.
  • a miniature motor for a timepiece comprising:
  • a non-magnetic stator having a central cylindrical cavity of a predetermined diameter and a predeter mined longitudinal dimension
  • bearing supports projecting perpendicularly to said disk closures
  • a permanent magnet member having a north and a south pole mounted on said shaft interiorly of said chamber;
  • winding means disposed in said slot means for providing a magnetic field of a predetermined direction
  • the major axis of said ellipse being greater in length than the minor axis of said ellipse to provide bias means for stopping the rotor in the same position after each energization of said winding means and for reducing the staltin g torque following the appli- 20-30 to said normal.
  • a miniature motor according to claim 4 wherein the interior surface of said windings is disposed away from the surfaces of said disk closures.
  • each of said closure disks includes a longitudinal sleeve along the bearing axis of said shaft and the shaft bearings are disposed at the ends of said sleeves.
  • stator includes a pair of longitudinal openings beyond the periphery of the disk closures, and includes contact members disposed in said openings.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)
  • Insulation, Fastening Of Motor, Generator Windings (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
US00304885A 1972-11-08 1972-11-08 Miniature motor Expired - Lifetime US3803430A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US00304885A US3803430A (en) 1972-11-08 1972-11-08 Miniature motor
DE7332063U DE7332063U (de) 1972-11-08 1973-09-04 Miniaturmotor für Zeitgeber
DE19732344502 DE2344502A1 (de) 1972-11-08 1973-09-04 Miniaturmotor fuer zeitgeber
JP48101260A JPS4995117A (enrdf_load_stackoverflow) 1972-11-08 1973-09-10
FR7333311A FR2205768A1 (enrdf_load_stackoverflow) 1972-11-08 1973-09-17
CH1328173A CH610474B5 (enrdf_load_stackoverflow) 1972-11-08 1973-09-17
CH1328173D CH1328173A4 (enrdf_load_stackoverflow) 1972-11-08 1973-09-17
SU731968215A SU625644A3 (ru) 1972-11-08 1973-11-06 Микроэлектродвигатель дл хронометра

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00304885A US3803430A (en) 1972-11-08 1972-11-08 Miniature motor

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US3803430A true US3803430A (en) 1974-04-09

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Application Number Title Priority Date Filing Date
US00304885A Expired - Lifetime US3803430A (en) 1972-11-08 1972-11-08 Miniature motor

Country Status (6)

Country Link
US (1) US3803430A (enrdf_load_stackoverflow)
JP (1) JPS4995117A (enrdf_load_stackoverflow)
CH (2) CH1328173A4 (enrdf_load_stackoverflow)
DE (2) DE2344502A1 (enrdf_load_stackoverflow)
FR (1) FR2205768A1 (enrdf_load_stackoverflow)
SU (1) SU625644A3 (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3940645A (en) * 1973-10-30 1976-02-24 Rhythm Watch Co. Ltd. Small-sized synchronous motor
US3949251A (en) * 1973-09-05 1976-04-06 Kabushiki Kaisha Daini Seikosha Stepping motor for a timepiece
US3982146A (en) * 1973-03-15 1976-09-21 Airborne Manufacturing Company Fluid cooled commutated electric motor
US4006374A (en) * 1975-02-19 1977-02-01 Kabushiki Kaisha Daini Seikosha Electric micro motor for a timepiece
US4115713A (en) * 1975-03-06 1978-09-19 Motorola, Inc. Rotor bias means for miniature watch motors or the like
US4186340A (en) * 1975-06-30 1980-01-29 Motorola, Inc. Apparatus for measuring the magnetic strength of magnetic work pieces
US4559461A (en) * 1983-06-23 1985-12-17 Jeco Company Limited Stepping motor
US6201324B1 (en) * 1998-07-28 2001-03-13 Minebea Co., Ltd. Stator pole teeth for a claw pole stepping motor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5167904A (ja) * 1974-12-08 1976-06-12 Ricoh Watch Parusumoota
CH617062B (fr) * 1976-12-22 Girard Perregaux Sa Moteur electrique a rotation discontinue pour mouvement de montre.

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3982146A (en) * 1973-03-15 1976-09-21 Airborne Manufacturing Company Fluid cooled commutated electric motor
US3949251A (en) * 1973-09-05 1976-04-06 Kabushiki Kaisha Daini Seikosha Stepping motor for a timepiece
US3940645A (en) * 1973-10-30 1976-02-24 Rhythm Watch Co. Ltd. Small-sized synchronous motor
US4006374A (en) * 1975-02-19 1977-02-01 Kabushiki Kaisha Daini Seikosha Electric micro motor for a timepiece
US4115713A (en) * 1975-03-06 1978-09-19 Motorola, Inc. Rotor bias means for miniature watch motors or the like
US4186340A (en) * 1975-06-30 1980-01-29 Motorola, Inc. Apparatus for measuring the magnetic strength of magnetic work pieces
US4559461A (en) * 1983-06-23 1985-12-17 Jeco Company Limited Stepping motor
US6201324B1 (en) * 1998-07-28 2001-03-13 Minebea Co., Ltd. Stator pole teeth for a claw pole stepping motor

Also Published As

Publication number Publication date
CH1328173A4 (enrdf_load_stackoverflow) 1977-04-15
CH610474B5 (enrdf_load_stackoverflow) 1979-04-30
FR2205768A1 (enrdf_load_stackoverflow) 1974-05-31
DE2344502A1 (de) 1974-05-16
SU625644A3 (ru) 1978-09-25
JPS4995117A (enrdf_load_stackoverflow) 1974-09-10
DE7332063U (de) 1973-12-20

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