US3813871A - Clock utilizing a magnetic escapement mechanism - Google Patents

Clock utilizing a magnetic escapement mechanism Download PDF

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Publication number
US3813871A
US3813871A US00340646A US34064673A US3813871A US 3813871 A US3813871 A US 3813871A US 00340646 A US00340646 A US 00340646A US 34064673 A US34064673 A US 34064673A US 3813871 A US3813871 A US 3813871A
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United States
Prior art keywords
shaft
wheel
escapement
worm
tuning fork
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Expired - Lifetime
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US00340646A
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English (en)
Inventor
M Hirose
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Jeco Corp
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Jeco Corp
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    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C5/00—Electric or magnetic means for converting oscillatory to rotary motion in time-pieces, i.e. electric or magnetic escapements
    • G04C5/005—Magnetic or electromagnetic means

Definitions

  • ABSTRACT A clock of the magnetic escapement type having a cyclically impulsed tuning fork mounted between frame plates which are formed of metal and synthetic resin, respectively.
  • the tuning fork is secured to the edge of a base plate having a body portion which lies between the legs of the tuning fork and having a mounting portion.
  • the base plate has a deep notch adjacent the region of securing of the tuning fork and the mounting portion engages a block of damping material secured to the frame.
  • One leg of the tuning fork cooperates with a magnetic escapement wheel mounted upon an escapement shaft which is vertically oriented.
  • the escapement shaft has a worm driving a worm wheel in such a way that the reaction force of the worm wheel acts in a direction opposite to the action of gravity.
  • the worm is of special anti-friction construction consisting of a coil spring with the corresponding portion of the shaft being annularly relieved.
  • the escapement shaft has a flywheel with a manual wiper for starting purposes with the flywheel being loose upon the shaft.
  • the present invention relates to a clock utilizing a magnetic escapement mechanism which is of simplified construction with a reduced number of parts, using only a single jeweled bearing, which is easy to assemble, whichhas lower material cost and improved shock resistance while maintaining a high degree of accuracy.
  • FIG. I is an exploded perspective view, partially schematic, showing a clock utilizing a magnetic escapement mechanism according to the present invention.
  • FIG. 1a is a detailed view of the starting member.
  • FIG. 2 is a perpsective view of the magnetic escapement mechanism and associated elements in partial section.
  • FIG. 3 shows on an enlarged scale the worm and worm wheel.
  • FIG. 4 is a chart illustrating the general efficiency of V the worm with the lead angle as abscissa and the efficiency as ordinate.
  • FIG. 5 is a fragmentary side view of the magnetic escapement mechanism of interest with respect to startmg.
  • FIG. 5a is a fragment showing the lower jeweled bearing in cross section.
  • FIG. 6 is an elevation corresponding to FIG. 5.
  • FIG. 7 is a chart illustrating the manner in which the magnetic escapement wheel is started, with the time as abscissa and the velocity as ordinate comparing characteristic A of the present invention and characteristic B e of the prior art.
  • FIG. 8 is an exploded fragmentary perspective view showing the support for the tuning fork as dismantled.
  • FIG. 9 is a fragmentary perspective view of the minute wheel.
  • a housing 11 which is preferably made of transparent or translucent synthetic resin.
  • the housing has a battery enclosing portion 12, providing battery contacts l4, l5, and a mechanism enclosing portion 13.
  • the housing provides access to a manually actuated starting member or wiper 16 which is pivoted at 17 and which has an outwardly projecting knob 20 ex tending through a suitable clearance opening.
  • a tip 22 At the upper end of the starting member 16 is a tip 22 which is positioned to engage the hub of a flywheel to be described.
  • the member has an integral spring 18 at its lower end which biases the member normally to a disengaged position. In operation the member is moved to the left and then released, with the return movement serving to impulse the mechanism.
  • the plate 31 is preferably formed of synthetic resin while the plate 24 is formed of metal.
  • the plate 24 serves to mount a magnetic escapement wheel 25 on an escapement shaft 27.
  • the shaft at its upper end engage a bearing 28 and at its lower end a bearing 29, the bearing 29 being detailed in FIG. 5a.
  • the means employed for inducing rotation in the magnetic escapement wheel 25 will be described in a subsequent section.
  • the escapement assembly it includes a flywheel 23 having a hub 47 which is freely rotatable with respect to the shaft 27. Encircling the hub 47 is a small annulus 48 of friction material such as rubber and which is placed in alinement with the tip 22 of the starting member (see FIG. 5.).
  • the worm in the presentinstance is formed by a coil spring 45 which encircles the shaft 27 and which is connected to-the shaft only at its ends.
  • the central portion of the spring that is, the portion engaged by the worm wheel, indicated at 43, is annularly relieved as shown at 44, being reduced to a minor diameter a.
  • the wire of which the coil spring 45 is formed may, for example, be light gage smoothly- 3 surfaced stainless steel.
  • the annular relief 44 permitting deeper engagement of the teeth on the worm wheel, brings about a number of advantages, one of the most important of which is the increase in efficiency.
  • Efficiency 11 of the worm may be generally expressed by the following equation:
  • n tan a/tan (a+p) 2
  • the efficiency takes the maximum value at y 45 p/ 2 and depends on selection of the lead angle 7 under the necessary condition that u. should be sufficiently small from the restriction in. design of the pressure angle a
  • the lead angle 7 is generally selected from a range between 10 and in view of the fact that the diameter of pitch circle would be reduced and the upper limit of strength would be encountered when a large lead angle 7 is intended.
  • the preferred embodiment of the present invention which employs a lead angle of 12 under consideration of the above mentioned problems assures a transmitting efficiency of about 80 percent. It is found that use of a plastic material for the worm wheel 43 is highly advantageous where stainless steel is used for the worm.
  • the direction of rotation of the escapement shaftand the hand of the worm are such that the reaction force of the teeth of the worm wheel acts in an upward direction, that is, a direction which tends to lift the vertical shaft 27 endwise against the force of gravity, thereby reducing the axial bearing pressure which acts at the lower jeweled bearing 29, a jeweled bearing being provided only at the lower end of the shaft.
  • Reduction in the bearing load at the lower end of the shaft assuming proper lubrication, naturally decreases the power lost in friction.
  • the present clock requires a minimum of driving torque to be imparted by the oscillatory system next to be described.
  • the magnetic oscillator which drives the magnetic escapement wheel, is in the form of a tuning fork which is made of a bent strip of metal having opposed legs 32, 36 with a bend, or bight 51 forming a mounting base.
  • a solenoid type coil 39 cooperates with an armature 37 in the form of a small permanent magnet. The latter is secured to a bracket 38 which is welded or otherwise secured to the end of the leg 32.
  • the coil 39 is supplied with alternating electrical impulses at a timed rate originating in a solid state timing circuit per se well known in the art and which does not form a part of the present invention. Vibration in the leg 32 induces vibration in the opposite leg 36.
  • a horsehoe magnet 34 Secured to the tip of the opposite leg is a horsehoe magnet 34 which straddles the escapement wheel.
  • the escapement wheel is provided with a series of teeth 35 and a series of spokes out of register therewith, the teeth and spokes together defining a zig-zag magnetic path which encircles the escape wheel.
  • the horehoe magnet 34 is vibrated backwardly and forwardly in a horizontal direction, the poles thereon, in passing from a spoke to a tooth and back again, causes the escapement wheel to rotate at a speed which is dependent upon the speed of vibration and the number of cycles of magnetic irregularity in the wheel.
  • the period of natural vibration of the tuning fork preferably corresponds to the period of the impulses supplied to the coil 39 so that the system operates in a condition of resonance.
  • the efficiency of the oscillating system in the condition of resonance is enhanced by the manner in which the tuning fork is mounted.
  • I provide a base plate 41 having a body portion 50 and mounting portion 52.
  • the body portion of the base plate is vertically arranged and centered between the legs of the tuning fork with the edge thereof secured by welding or the like to the center of the base or bent portion 51 of the tuning fork.
  • the base plate 41 is sharply reduced in section by forming a deep notch 49 between the body 41 and mounting portion 52, the notch extending inwardly from a region adjacent the point of attachment of the tuning fork and extending parallel to the latter.
  • Such notching, or relief provides the base plate with lateral freedom and permits the base plate to resiliently yield at the region of attachment of the tuning fork. It is found that this results in a number of advantages. in the first place energy is more efficiently transmitted from the driving leg 32 of the tuning fork to the driven leg 36 with minimum absorption of the vibrational energy in the base plate or base plate mounting.
  • the provision of the deep notch 49 serves to isolate the vibratory system from its mount which not only sharply reduces the amount of energy transmitted to the mount but results in a substantial increase in the efficiency of Q factor of the oscillatory system, enabling the latter to be driven with a minimum amount of electrical energy.
  • the block 42 is formed of sintered metal or alloy.
  • a sintered body may be produced by molding brass powders preferably of less than 150 mesh, either by itself or with addition of lead powder with heat and compression to the point of incipient fusion and to a density which is about 80 percent of the density of the raw material. Not only does the sintering permit the economic manufacture of a relatively massive block of high dimensional accuracy, but the porous nature of the result has been found to improve the dampening characteristics and to still further reduce the amount of energy transmitted to the clock frame.
  • the plate 311 on the other side being formed of synthetic resinous material acts, of itself, as a poor transmitter of vibrational energy with high dampening effect.
  • the parts are clamped together by means of a machine screw 53 which passes through the plate 24, block 42, mount 52 and then the plate 31 with a nut holding the sandwich thus formed tightly and permanently together.
  • an adjusting screw is threaded into the plate 24.
  • the adjusting screw which is spring loaded to prevent wandering of the adjustment, carries a small permanent magnet 61 at its tip, which magnet has the effect of slowing the vibration of the leg 36 depending upon the degree of proximity. It is found that once adjusted a clock constructed inaccordance with the present designs all operate for long periods with a high degree of accuracy.
  • the driving circuitry for the coil 39 may be selected with components having a high degree of stability, the components being sufficiently compact as to permit mounting within a small capsule 40 within the clock housing.
  • a clock of the present type requires application of a starting impulse to the escapement wheel. This is accomplished by moving the starting member 16 to the left and releasing it, whereupon the tip 22 of the member engages the frictional ring 48 on the flywheel hub 47 with a wiping action.
  • the flywheel 23 is not keyed to the escapement shaft but is slidably mounted upon it. As a result, only limited torque is ap plied, by friction, to the escapement shaft so that the shaft is rotated at a relatively slow speed into the synchronization band.
  • the synchronization band is indicated at C in FIG. 7 and is the range of speed within which the escapement wheel will synchronize.
  • a clock of the present design has been found to be unusually resistant to shock or vibration applied in any direction.
  • the clock is highly economical, being substantially maintenance-free and constructed of a minimum number of simply formed, and easily assembled, parts.
  • a frame comprising a pair of frame plates horizontally spaced from one another, a resilient vibrating member extending horizontally between the plates and mounted at one end with respect to the plates while the other is free to vibrate horizontally, means including a coil energized by alternating current for cyclically impulsing the vibrating member, a magnet mounted on the vibrated end of the member for moving with it in a horizontal plane, a magnetic escapement wheel mounted in a horizontal plane adjacent the vibrated member and having a zig-zag magnetic path cooperating with the magnet to induce rotation in the wheel, said wheel having an escapement shaft which extends vertically between the plates, vertically spaced bearings including a lower thrust bearing secured to one of the plates for engaging the respective ends of the escapement shaft, the shaft having a worm and cooperating worm wheel, the direction of rotation of the shaft and the hand of the worm being such that the endwise reaction force of the worm wheel upon the worm is such as to tend to lift the shaft thereby to reduce the end
  • a clock mechanism comprising a frame, a tuning fork formed of a flat strip bent into U-shape to define a curved base and first and second legs arranged parallel to one another, a flat base plate centered between the legs of the tuning fork and parallel to the latter, the base plate having a body portion and a mounting portion, the mounting portion of the base plate being clamped to the frame, the body portion of the base plate having one edge secured in centered position inside the curve of the base of the tuning fork, means including a coil and source of a-c.
  • the base plate being of sharply reduced section in the region between the body portion and the mounting portion so as to permit relatively free resilient movement of the body portion on which the tuning fork is mounted thereby to facilitate transfer of energy from the first leg of the tuning fork to the second leg while minimizing transfer of energy to the frame, and indicator means coupled to the escapement wheel shaft.
  • a clock comprising a frame, a magnetic escapement wheel having a shaft mounted in the frame, a vibrated element mounted on the frame at one of its ends, means for cyclically impulsing the vibrated member, the vibrated element having a magnet at the other end for cooperating with the escapement wheel so that the wheel is timingly advanced as the magnet oscillates back and forth, a flywheel having a hub frictionally slidable on the shaft, a manually operated starting member having means for wipingly engaging the hub to initiate rotation of the magnetic escapement wheel, and indicator means coupled to the escapement shaft.
  • the starting member is in the form of a pivoted lever having a tip which frictionally engages the hub with a wiping action, the lever including means for normally biasing the same out of engagement with the hub but manually movable into engagement therewith and with the biasing force serving to impulse the flywheeel forwardly when the wiper is manually released.
  • the combination comprising a synethetic resin plate and a metallic plate horizontally spaced from one another, two vibrating members interposed between said plates for horizontal vibrating motion, a magnet mounted on the tip of one of said vibrating members for horizontal vibrating motion, a vertical escapement shaft having a magnetic escapement wheel and an inertia wheel mounted thereon in a horizontal plane, and having a worm mounted thereon for cooperation with a worm wheel, said escapement wheel having a zig-zag magnetic path for magnetic coupling with said vibrating magnet, and a regulator mounted on the metallic plate for regulating the frequency of vibration, the regulator being in the form of a small permanent magnet arranged in the vicinity of one of the vi- I brating members and having a screw threaded in the metallic plate for adjustably positioning the permanent magnet toward and away from the one vibrating member.
  • a time gear wheel disposed in a vertical plane and coupled to the worm wheel, said gear wheel having a regulator shaft rigidly fixed to its center and extending horizontally from and perpendicular to said vertical plane a distance far enough to provide access vertical plane; a vertically extending regulator shaft having a horizontally disposed gear wheel at one end for coupling to the annular gear teeth, the other end of said shaft extending a sufficient distance to provide access to it, thereby providing means for adjusting said time gear wheel to a reference point.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Gear Transmission (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
US00340646A 1972-10-27 1973-03-13 Clock utilizing a magnetic escapement mechanism Expired - Lifetime US3813871A (en)

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JP1972123414U JPS4977371U (ja) 1972-10-27 1972-10-27

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS51135573U (ja) * 1975-04-23 1976-11-01
US20090130624A1 (en) * 2007-11-20 2009-05-21 Benjamin Jiemin Sun Methods and kits for making flexible dental guards
US20150177696A1 (en) * 2013-12-23 2015-06-25 The Swatch Group Research And Development Ltd Regulating device
US20150234360A1 (en) * 2013-12-18 2015-08-20 Leon Gerhard KARSTEN Construction arrangement applied to electromagnetic or magnetic watch

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3171991A (en) * 1962-01-08 1965-03-02 Baumer Herbert Electromagnetically actuated tuning fork drive adapted for clockwork
US3208287A (en) * 1961-10-21 1965-09-28 Jeco Kk Magnetic escapement
US3212252A (en) * 1963-06-04 1965-10-19 Citizen Watch Co Ltd Vibratory motor and controlled circuit for a small timepiece
US3277644A (en) * 1965-06-08 1966-10-11 Jeco Kk Tuning fork timepiece
US3433984A (en) * 1965-11-29 1969-03-18 Brac Ltd Devices for converting rotary vibrations into unidirectional rotary movement
US3504301A (en) * 1967-01-31 1970-03-31 Centre Electron Horloger Mechanical oscillator
US3532912A (en) * 1968-02-20 1970-10-06 Clifford Cecil F Electromechanical oscillator with rotary output
US3566167A (en) * 1968-11-02 1971-02-23 Omega Brandt & Freres Sa Louis Apparatus for conversion of reciprocating motion into rotating motion
US3577874A (en) * 1967-06-27 1971-05-11 Muller Schlenker Electric clocks with magnetic drives
US3609958A (en) * 1969-03-07 1971-10-05 Mauthe Gmbh Friedr Magnetic device for transforming an oscillatory motion into a rotary motion

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1204654A (en) * 1969-05-16 1970-09-09 Cohon Pao Improvements in or relating to a worm gear

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3208287A (en) * 1961-10-21 1965-09-28 Jeco Kk Magnetic escapement
US3171991A (en) * 1962-01-08 1965-03-02 Baumer Herbert Electromagnetically actuated tuning fork drive adapted for clockwork
US3212252A (en) * 1963-06-04 1965-10-19 Citizen Watch Co Ltd Vibratory motor and controlled circuit for a small timepiece
US3277644A (en) * 1965-06-08 1966-10-11 Jeco Kk Tuning fork timepiece
US3433984A (en) * 1965-11-29 1969-03-18 Brac Ltd Devices for converting rotary vibrations into unidirectional rotary movement
US3504301A (en) * 1967-01-31 1970-03-31 Centre Electron Horloger Mechanical oscillator
US3577874A (en) * 1967-06-27 1971-05-11 Muller Schlenker Electric clocks with magnetic drives
US3532912A (en) * 1968-02-20 1970-10-06 Clifford Cecil F Electromechanical oscillator with rotary output
US3566167A (en) * 1968-11-02 1971-02-23 Omega Brandt & Freres Sa Louis Apparatus for conversion of reciprocating motion into rotating motion
US3609958A (en) * 1969-03-07 1971-10-05 Mauthe Gmbh Friedr Magnetic device for transforming an oscillatory motion into a rotary motion

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS51135573U (ja) * 1975-04-23 1976-11-01
JPS6029749Y2 (ja) * 1975-04-23 1985-09-07 株式会社精工舎 電池時計用ム−ブメントの構造
US20090130624A1 (en) * 2007-11-20 2009-05-21 Benjamin Jiemin Sun Methods and kits for making flexible dental guards
US20150234360A1 (en) * 2013-12-18 2015-08-20 Leon Gerhard KARSTEN Construction arrangement applied to electromagnetic or magnetic watch
US20150177696A1 (en) * 2013-12-23 2015-06-25 The Swatch Group Research And Development Ltd Regulating device
US9389591B2 (en) * 2013-12-23 2016-07-12 The Swatch Group Research And Development Ltd Regulating device

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Publication number Publication date
FR2204830A1 (ja) 1974-05-24
FR2204830B1 (ja) 1980-01-04
JPS4977371U (ja) 1974-07-04

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