US3816779A - Bistable electromechanical transducer - Google Patents

Bistable electromechanical transducer Download PDF

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Publication number
US3816779A
US3816779A US00346092A US34609273A US3816779A US 3816779 A US3816779 A US 3816779A US 00346092 A US00346092 A US 00346092A US 34609273 A US34609273 A US 34609273A US 3816779 A US3816779 A US 3816779A
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US
United States
Prior art keywords
rotor
pole
stator
air gap
bistable
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
US00346092A
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English (en)
Inventor
R Lundin
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.)
GEN TIME CORP
GENERAL TIME CORP US
General Time Corp
Original Assignee
GEN TIME CORP
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 GEN TIME CORP filed Critical GEN TIME CORP
Priority to US00346092A priority Critical patent/US3816779A/en
Priority to GB5986273A priority patent/GB1452100A/en
Priority to CA189,413A priority patent/CA996173A/en
Priority to DE2401135A priority patent/DE2401135A1/de
Priority to IT67121/74A priority patent/IT1004735B/it
Priority to CH110974A priority patent/CH589883B5/xx
Priority to CH110974D priority patent/CH110974A4/xx
Priority to FR7403770A priority patent/FR2223881B3/fr
Priority to JP2001974A priority patent/JPS5626215B2/ja
Application granted granted Critical
Publication of US3816779A publication Critical patent/US3816779A/en
Assigned to MARINE MIDLAND BUSINESS LOANS, INC. reassignment MARINE MIDLAND BUSINESS LOANS, INC. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GENERAL TIME CORPORATION, F/K/A TIME ACQUISITION CORP. A CORP. OF DELAWARE
Assigned to GENERAL TIME CORPORATION reassignment GENERAL TIME CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: TALLEY INTERNATIONAL INVESTMENT CORPORATION
Assigned to BARCLAYS BUSINESS CREDIT, INC., A CORPORATION OF CT reassignment BARCLAYS BUSINESS CREDIT, INC., A CORPORATION OF CT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GENERAL TIME CORPORATION, A CORP. OF DE
Assigned to GENERAL TIME CORPORATION, NORCROSS, GA A CORP. OF DE reassignment GENERAL TIME CORPORATION, NORCROSS, GA A CORP. OF DE RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). RELEASE OF SECURITY INTEREST RECORDED AT REEL 5092 FRAME 572 Assignors: MARINE MIDLAND BUSINESS LOANS, INC., A CORP. OF DE
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C13/00—Driving mechanisms for clocks by master-clocks
    • G04C13/08—Slave-clocks actuated intermittently
    • G04C13/10—Slave-clocks actuated intermittently by electromechanical step advancing mechanisms
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system
    • H02K33/16—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with polarised armatures moving in alternate directions by reversal or energisation of a single coil system

Definitions

  • the stator is separated at its ends to form a generally circular June ll, 1974 air gap with the ends of the stator forming a pair of pole faces.
  • a rotor is positioned in the air gap and includes a permanent magnet sandwiched between two parallel discs of high permeability material. The discs each have a plurality of working rotor pole faces with one of the discs having an extra pole face designated the holding pole.
  • the rotor holding pole when in a central neutral position, extends into a channel formed by the separated ends of the stator core. As the rotor rotates toward either of its stable positions, the holding pole comes into increasing angular alignment with the respective portions of the stator core to which it is attracted, there being a substantially constant radial air gap separating the rotor holding pole and the stator. Because of the constant radial air gap, the holding pole is attracted toward either end of the stator core by a torque which is substantially constant as the rotor approaches either of its stable positions.
  • This invention relates to an efficient and reliable bistable electromechanical transducer.
  • a transducer In electrically operated timepieces, such as watches, a transducer is required to translate the electrical impulses derived from an input, such as a high-frequency oscillator, to mechanical motion. Such a transducer must have a very low average power consumption because of the low capacity of the small batteries which are typically mounted in watches. A number of transducers have appeared on the market, but these have been found to suffer serious drawbacks in reliability and efficiency in converting exceedingly low power, low duty cycle input pulses into mechanical motion.
  • bistable electromechanical transducer capable of being operated by a very low power source of electrical energy having:
  • the transducer includes a stator having a core with an energizing winding wound thereabout.
  • the core is separated at its ends to form a generally circular air gap and at least two stator pole faces.
  • a rotor is positioned in the air gap, the rotor including a permanentmagnet positioned between a pair of parallel discs of high permeability.
  • the rotor has a plurality of working pole faces, each of which has an arc length sufficiently great so that, regardless of the position of the rotor as it moves from one bistable position to the other, the fringing permeance rates of change for the entering and leaving poles are substantially equal in magnitude (though opposite in sign) over the working stroke of the rotor within its design limits.
  • FIG. 1 is a plan view of a prior art electromechanical transducer
  • FIG. 2 is a plan view of the electromechanical transducer of this invention.
  • FIG. 3 is a cross-sectional view of the rotor of this invention taken along lines 3-3 of FIG. 2;
  • FIG. 4 is a graphical display of the torque curves associated with the prior art electromechanical transducer shown in FIG. 1;
  • FIG. 5 is a graphical display of the torque curves associated with the electromechanical transducer illustrated in FIG. 2;
  • FIG. 6(a) is a partial cutaway plan view of the rotor and stator of this invention showing the rotor in a first bistable position;
  • FIG. 6(b) is a partial plan view of the rotor and stator of this invention showing the rotor in the second bistable position;
  • FIG. 7(a) is a linear representation of the circular system shown in FIGS. 2 and 6 in which the armature poles correspond to the rotor of this invention.
  • FIG. 7(b) is an illustrative representation particularly showing the fringe permeance relationship of one set of the stator and armature poles.
  • FIG. 1 where there is shown a prior art embodiment of a bistable electromechanical transducer, which is fully disclosed in co-pending application Ser. No. 245,592 filed Apr. 19, 1972 for Quartz Crystal Controlled Stepper Motor and assigned to the common assignee herewith.
  • a stator 11 is shown having an energizing winding 13 wound about a leg portion 15 thereof.
  • the stator is separated at its ends to form a generally circular air gap.
  • the ends of the stator are notched to form a plurality of pole faces l7 and 19.
  • a circular rotor Positioned within the air gap is a circular rotor which includes a permanent magnet (not shown) positioned between a pair of discs 21 and 23.
  • disc 21 Because of the permanent magnet, disc 21 has a south pole polarization and disc 23 has a north pole polarization.
  • a plurality of teeth25 and 27 are formed in the discs 21 and 23, respectively. These teeth form a plurality of rotor pole faces which interact with the stator poles l7 and 19 to drive the rotor when winding 13 is energized.
  • a holding pole 29 extends from the south pole disc 21 into a channel formed between the ends of stator 11.
  • the pole has, a pair of side surfaces 31 which form a pair of pole faces.
  • This pole serves a dual function, namely, to hold the rotor in one of two bistable positions and to prevent continuous rotation of the rotor as in a rotary motor.
  • -Attached to the axle 35 of the rotor is a pallet arm 37 having a pair of pallet jewels 39 secured at each end thereof.
  • the pallet jewels impart intermittent motion to an escapement wheel 41 by intermittently striking the gear teeth of the escapement wheel as the rotor oscillates about axle 35.
  • FIG. 4 is a graphical display of the torque curves associated with this prior art transducer.
  • the vertical line 32' on the left end of the diagram represents stator pole face 32 and the line 33 on the right end of the diagram represents the pole face 33.
  • the distance between line 32' and line 40 represents the thickness of the nonmagnetic gap separation element 36 shown in FIG. 1 on the holding pole 29.
  • the distance between line 33' and line 42 represents the thickness of the nonmagnetic gap separation element 38 on the opposite side of the holding pole from element 36.
  • a second quiescent torque is that due to the inequality in the magnitude of the. rate of change of the fringing permeances of each entering pole, and its corresponding leavingpole.
  • This torque has the effect of causing the rotor to find a stable state at or near the center of the stroke where this torque curve crosses the zero axis and has a negative slope.
  • the reason for its existance has been alluded to as the difference in magnitude between the rate of change of fringing permeance of the entering pole, and that of the leaving pole.
  • the magnetomotive force across the P and P air gaps is therefore equal tothe m.m.f. across the P and P air gaps. It follows therefore that the m.m.f. across P and P as well as the m.m.f. across P and P is equal to one half of the total available m.m.f. from the magnet.
  • This centering torque though small in magnitude, can have a substantial influence because the input pulses to the energizing winding 13 in a watch movement is typically of exceedingly short time duration, i.e., of low duty cycle, compared to the frequency of the bistable transducer. Because of this, the drive torque may not be present during the entire transition period of the rotor from one bistable position to the other. Thus, if the pulse ceases before the rotor passes the center point, the rotor will become temporarily immobilized in a center position. As aforementioned, when this occurs the escapement wheel 41 is free to rotate in any direction thereby introducing error in the timekeeping mechanism.
  • FIG. 2 is a plan view of the improved bistable transducer of this invention which transducer overcomes the problems associated with the aforementioned prior device.
  • a stator 51 having an energizing winding 53 wound about the core portion thereof.
  • the core is separated at its ends to form a generally circular air gap.
  • a pair of pole faces 55 and 57 are formed at the ends of the stator having a predetermined arc length and depth.
  • a rotor is shown having a permanent magnet 69, as best illustrated in FIG. 3, sandwiched between two parallel discs of high permeability material.
  • Disc 59 is polarized because of the permanent magnet as a north pole and disc 61 has a south pole polarization.
  • a holding pole 63 is formed in the south disc 61 with the pole having an arm portion 64 bent upward so as to form a pole face for interacting with the stator core surfaces 65 and 67.
  • the surface 64 of the holding pole has a constant radial displacement with respect to the stator core surfaces 65 and 67. Because of the structure of the holding pole and its constant spaced relationship with respect to the stator surfaces 65 and 67, the magnetic permeance between the stator and the holding pole increases substantially linearly as the holding pole moves into increasing angular alignment with either of stator surfaces 65 and 67.
  • stator surface 67 is proportional to the rate of change of permeance therebetween, (which is substantially constant as the rotor moves into increasing angular alignment with the stator), the torque attracting pole 63 toward stator core surface 67 is substantially constant as the pole approaches its bistable position.
  • constancy of the torque holding the pole 63 to the stator core prevents the possibility of the rotor from becoming locked in one or the other of the two bistable positions.
  • a pallet arm 70 is shown secured fast to axel 35.
  • Pallet arm 70 is nonmagnetic and has a pair of jewels 71 at each end thereof for engaging and stepping an escapement wheel, as disclosed in more detail in co-pending application Ser. No. 245,592 referred is hereinbefore.
  • a fork extension 72 which co-acts with a stationary member on the bridge of the movement (not shown) to serve as a positive stop in each oscillating direction of the rotor.
  • FIG. 3 Illustrated in FIG. 3 is a cross-sectional view of the rotor showing the position of the permanent magnet 69 between discs 59 and 61.
  • the teeth of the rotor are bent inward toward each other so as to form a plurality of interleaved pole faces for interacting with the pole faces of the stator core.
  • a bushing 28 is inserted through a hole in each of the discs and through a hole in the permanent magnet positioned therebetween. This bushing is rigidly secured to the permanent magnet and to the discs by any suitable adhesive component known in the art.
  • Holding pole 63 is shown extended upward so that it can interact with stator surfaces 65 and 67.
  • a counterweidht 74 is shown secured to bushing 28 for balancing or poising the rotor assembly.
  • FIG. is a graphical display of the torque curves associated with the bistable transducer of this invention.
  • the left-hand line designates the extreme clockwise rotative position of the rotor and the right-hand line designates the extreme counterclockwise position of the rotor.
  • the rotor rotates through a total angle of so that each line represents an angular displacement of 792 from a center position.
  • a positive torque drives the rotor in a counterclockwise direction
  • curve 90 it can be seen from curve 90 that the holding torque generated by the permanent magnetic field passing through the holding pole 63 and the stator core increases rapidly as the holding pole rotates in the counterclockwise direction from center toward stator core surface 67. After the surface of the holding pole 63 starts to move into angular algiment with surface 67, the holding torque becomes substantially constant with further rotation of the rotor.
  • FIGS. 6a and 6b are partial cut-away views showing the two bistable positions of the rotor.
  • north rotor pole 59 is positioned in its extreme clockwise bistable rest position.
  • Lines of magnetic flux pass between the north rotor working pole and the stator pole 55 as shown through the permeance P
  • a leakage flux passes from the rotor pole to the stator pole through permeance P along the side 54 thereof extending from the main body of the stator to the face of the stator pole 55.
  • the south pole disc of the rotor also has a working pole 91 positioned opposite stator pole 55.
  • Flux lines are shown extending between the south rotor pole 91 and the stator pole 55 through the permeance P
  • leakage flux lines are shown extending between rotor ple 91 and the side surface 56 of the stator pole 55 through the permeance P
  • the south rotor pole 91 has a sufficient arc length so that at least a protion thereof extends downward beyond the normal surface area in which the flux and leakage flux lines impinge.
  • the extension of the rotor pole arc length beyond the limits of the stator pole should be as great as possible with respect to the intended displacement of the rotor.
  • edges SQ and 56 of the stator pole do not extend an infinite distance back from the stator pole face, and thus the fringing permeances P and P are defined by a maximum outside radius R, equal to the sum of the radial airgap and the radial length of the stator pole edge 54 or 56, respectively.
  • this pole extension corresponds to approximately 7. To allow for manufacturing variations this is increased in the preferred embodiment to I0.
  • FIG. 6(b) shows the rotor 59 as its extreme counterclockwise position.
  • rotor pole 90 is shown having an arc length great enough so that at least a 10 arc length thereof extends beyond the edge 54 of the stator pole.
  • the design of the present bistable transducer eliminates centering torques and, in addition, desensitizes the operation of the transducer to slight variances in the mechanical tolerances of the rotor and stator structure. Accordingly, an exceedingly reliable transducer is provided which can be driven by a low duty cycle, low power input signal with substantial reliability.
  • a bistable electromechanical transducer comprising in combination a stator including a core and an energizing winding wound about said core, said core being separated at its ends to form a generally circular air gap, the periphery of said air gap including at least two stator pole faces; means for energizing said winding with low duty cycle input pulses; a rotor including a permanent magnet and a pair of discs of high permeability material secured to each end of said magnet in substantial parallel relationship to one another, each of said discs having a plurality of pole faces, means including at least one holding pole for maintaining the rotor in either of its stable positions during the period between said input pulses wherein the rate of change of the permeance of the air between said holding pole and said stator is substantially constant as said rotor approaches either of its stable positions.
  • bistable electromechanical transducer of claim 1 capable of operation at very low electrical energy and wherein said means for maintaining the rotor in either of its stable positions comprises a holding pole being separated from the portions of the stator to which it is attracted by a substantially constant radial air gap,
  • bistable electromechanical transducer of claim 2 further comprising means for preventing said rotor from becoming temporarily locked in a neutral center position between said bistable positions, said means including the arc length of said rotor pole faces being great enough so that the total permeance of the air gap between said rotor and said stator remains substantially constant as the rotor moves from one bistable position to the other.
  • bistable electromechanical transducer of claim 3 wherein said means for preventing said rotor from becoming temporarily locked in a center position comprises rotor pole faces having an arc length such that regardless of the position of the rotor substantially all of the leakage flux from the stator pole faces impinges upon the rotor pole faces. 5.
  • a bistable electromechanical transducer comprising a stator including a high permeability core and an energizing winding wound about said core, said core being separated at its ends to form an air gap, the periphery of said gap including two stator pole faces; means for energizing said winding with input pulses; a rotor including a permanent magnet and a pair of high permeability armatures secured to each end of said magnet in substantial parallel relationship to one another, each of said armatures having two of pole faces, and means including at least one holding pole for maintaining the rotor in either of its stable positions during the period between said input pulses wherein the rate of change of the magnetic permeance between said holding pole and said stator is substantially constant as said rotor approaches either of its stable positions.
  • bistable electromechanical transducer of claim 5 wherein said holding pole has a predetermined arc length and oscillates from one stable position to the other adjacent a channel formed in said stator, said channel having an opening greater than the arc length of the holding pole, whereby the magnetic permeance between rotor and stator increases as the rotor rotates beyond the central or neutral position thereof toward one of said stable positions.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromechanical Clocks (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
US00346092A 1973-03-29 1973-03-29 Bistable electromechanical transducer Expired - Lifetime US3816779A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US00346092A US3816779A (en) 1973-03-29 1973-03-29 Bistable electromechanical transducer
GB5986273A GB1452100A (en) 1973-03-29 1973-12-27 Bistable electromechanical transducers
CA189,413A CA996173A (en) 1973-03-29 1974-01-03 Bistable electromechanical transducer
DE2401135A DE2401135A1 (de) 1973-03-29 1974-01-10 Bistabiler elektromechanischer wandler
IT67121/74A IT1004735B (it) 1973-03-29 1974-01-16 Trasduttore elettromeccanico bista bile
CH110974D CH110974A4 (ja) 1973-03-29 1974-01-28
CH110974A CH589883B5 (ja) 1973-03-29 1974-01-28
FR7403770A FR2223881B3 (ja) 1973-03-29 1974-02-05
JP2001974A JPS5626215B2 (ja) 1973-03-29 1974-02-21

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00346092A US3816779A (en) 1973-03-29 1973-03-29 Bistable electromechanical transducer

Publications (1)

Publication Number Publication Date
US3816779A true US3816779A (en) 1974-06-11

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00346092A Expired - Lifetime US3816779A (en) 1973-03-29 1973-03-29 Bistable electromechanical transducer

Country Status (8)

Country Link
US (1) US3816779A (ja)
JP (1) JPS5626215B2 (ja)
CA (1) CA996173A (ja)
CH (2) CH110974A4 (ja)
DE (1) DE2401135A1 (ja)
FR (1) FR2223881B3 (ja)
GB (1) GB1452100A (ja)
IT (1) IT1004735B (ja)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3999369A (en) * 1974-04-18 1976-12-28 Valroger Pierre Albert Marie D Electromechanical watch movement
US4346319A (en) * 1980-04-15 1982-08-24 Brother Kogyo Kabushiki Kaisha Rotary electromagnetic actuator
US4912690A (en) * 1986-03-03 1990-03-27 Rhythm Watch Co., Ltd. Timepiece movement
US20170176938A1 (en) * 2015-12-18 2017-06-22 Montres Breguet S.A. Safety regulation for a timepiece escapement
US10948881B2 (en) * 2017-08-04 2021-03-16 The Swatch Group Research And Development Ltd Timepiece movement fitted with an electromagnetic transducer

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5790818U (ja) * 1980-11-21 1982-06-04
JPS61154816A (ja) * 1984-12-27 1986-07-14 Kaijirushi Hamono Kaihatsu Center:Kk ナイフ等の製造方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2444178A (en) * 1945-11-02 1948-06-29 Tessie Weinberger Stroboscopic apparatus for calibrating time indicating devices
US3095690A (en) * 1959-03-23 1963-07-02 Hamilton Watch Co Contact and index system for an electric watch
US3142789A (en) * 1960-07-13 1964-07-28 Chester R Rhodes Bidirectional positioning device
US3435311A (en) * 1965-02-08 1969-03-25 Suwa Seikosha Kk Oscillatory electromechanical converter
US3737746A (en) * 1972-04-19 1973-06-05 Gen Time Corp Quartz crystal controlled stepper motor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2444178A (en) * 1945-11-02 1948-06-29 Tessie Weinberger Stroboscopic apparatus for calibrating time indicating devices
US3095690A (en) * 1959-03-23 1963-07-02 Hamilton Watch Co Contact and index system for an electric watch
US3142789A (en) * 1960-07-13 1964-07-28 Chester R Rhodes Bidirectional positioning device
US3435311A (en) * 1965-02-08 1969-03-25 Suwa Seikosha Kk Oscillatory electromechanical converter
US3737746A (en) * 1972-04-19 1973-06-05 Gen Time Corp Quartz crystal controlled stepper motor

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3999369A (en) * 1974-04-18 1976-12-28 Valroger Pierre Albert Marie D Electromechanical watch movement
US4346319A (en) * 1980-04-15 1982-08-24 Brother Kogyo Kabushiki Kaisha Rotary electromagnetic actuator
US4912690A (en) * 1986-03-03 1990-03-27 Rhythm Watch Co., Ltd. Timepiece movement
US20170176938A1 (en) * 2015-12-18 2017-06-22 Montres Breguet S.A. Safety regulation for a timepiece escapement
US10228659B2 (en) * 2015-12-18 2019-03-12 Montres Breguet S.A. Safety regulation for a timepiece escapement
US10948881B2 (en) * 2017-08-04 2021-03-16 The Swatch Group Research And Development Ltd Timepiece movement fitted with an electromagnetic transducer

Also Published As

Publication number Publication date
FR2223881A1 (ja) 1974-10-25
JPS5626215B2 (ja) 1981-06-17
JPS49129110A (ja) 1974-12-11
FR2223881B3 (ja) 1976-11-26
GB1452100A (en) 1976-10-06
DE2401135A1 (de) 1974-10-03
CA996173A (en) 1976-08-31
CH110974A4 (ja) 1976-11-15
CH589883B5 (ja) 1977-07-29
IT1004735B (it) 1976-07-20

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Owner name: MARINE MIDLAND BUSINESS LOANS, INC., GEORGIA

Free format text: SECURITY INTEREST;ASSIGNOR:GENERAL TIME CORPORATION, F/K/A TIME ACQUISITION CORP. A CORP. OF DELAWARE;REEL/FRAME:005092/0512

Effective date: 19880330

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Effective date: 19901105

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Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:MARINE MIDLAND BUSINESS LOANS, INC., A CORP. OF DE;REEL/FRAME:005665/0004

Effective date: 19901105