US2654989A - Timekeeping magnetic escapement and rotor unit therefor - Google Patents

Description

Oct. 13, 1953 TIMEKEEPING M. P. NICHOLS MAGNETIC-ESCAPEMENT AND ROTOR-UNIT THEREFOR iled Dec. 1, 1950 MM J m M Patented Oct. 13, 1953 TIMEKEEPIN G MAGNETIC ESCAPEMEN T AND ROTOR UNIT THEREFOR Malcolm P. Nichols, deceased, late of North Haven, Conn., by Mabel T. Nichols, executrix,

North Haven,

Conn., assignor to The E. Ingraham Company, Bristol, Conn., a corporation Application December 1, 1950, Serial No. 198,523

4 Claims.

The present invention relates to improvements in timekeeping magnetic-escapements and rotorunits therefor, i. e., escapements and rotor-units which are controlled by magnetism rather than by mechanical means. Broadly speaking, magnetic-escapements of the general character above referred. to have been previously devised, but the present invention is concerned with and has for its primary object the provision of a magnetic-escapement which will reliably self-start under the urge of rotary force applied to its rotor-unit and thereafter under the control of its vibrating magnetic-member, continue to operate to keep accurate time.

Another and more specific object of the present invention is to provide a superior rotor-unit which will serve to initiate the vibratory movement at low amplitude of a vibratory magneticmember, and thereafter progressively increase the amplitude of the movement of the said member until the said amplitude has reached the desired maximum.

With the above and other Objects in view, as will appear to those skilled in the art from the present disclosure this invention includes all features in the said disclosure which are novel over the prior art.

' In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is an elevational view of one form of timekeeping magnetic-escapement which the present invention may assume;

Fig. 2 is an elevational view of the showing of Fig. 1 but viewing the same in the direction of the arrow 3 of Fig. 1;

Fig. 3 is a broken detail sectional view taken on the line 3-3 of Fig. 1, but on a larger scale;

- Fig. 4 is a similar view but taken on'th line 44 of Fig. 1

Fig. 4A isa diagrammatic view of a part of an escape wheel and an associated pole-salient of the magnetic escapement shown in Fig. 1;

Fig. 5 is an elevational view similar to Fig. 1, but showing another form which the present invention may assume and showing the permanent magnet in section; and

Fig. 6 is an elevational view of the showing of Fig. 5 but viewing the same in the direction of the arrow 6 of Fig. 5. 7

The showingof Figs. 1 to 4 inclusive generally designated by the reference character It and in turn comprising two parallel but laterally-spaced-apart side arms II and I2 integrally connected together by a base-reach [3. The magnetic-member or -unit also includes a pair of similar ccmplemental pole-salients i4l4 one of which is located at the end of each of the sidearm II and [2 of the permanent magnet l0 and remote from the base-reach 13. The said polesalients extend in parallelism with each other in plane perpendicular with respect to the flatwise plane of the permanent magnet 19. The said pole-salients I i-4t have their inner faces spaced from each other sumciently to freely accommodate a rotor-unit between them as will be presently described.

The permanent magnet ll] above referred to be formed of any suitable magnetic material having high retentivity such, for instance, as high carbon or cobalt steel, as may also the pole-salients lld. The pole-salients i l-14, however, may be of soft iron or its equivalent and are preferably brazed or otherwise rigidly secured to the inner edge of the adjacent ends of the side arms E I and 12.

The magnetic member or -unit also includes a flexible reed 15 which is rigidly secured at one end in any suitable manner to the base-reach [3 of the permanent magnet It. The said reed is located intermediate the side arms H and I2 and has its end opposite the base-reach i3 rigidly secured to any suitable support such, for instance, as the fixed support It indicated in Figs. 1 and 2. Th said reed I5 is preferably formed of nonmagnetic material such as Phosphor bronze or beryllium copper, and is so related as to permit the permanent magnet i9 and the parts carried thereby to vibrate at the desired frequency and through the desired amplitude.

Positioned so as to rotate between the polesalients Ill-l4 of the permanent magnet I0 is a control ring generally designated by the reference character I1 and preferably formed of soft iron or other highly-permeable magnetic material to thus minimize hysteresis losses. In a circumferential direction, the said control-ring is of sinusoidal or serpentine form with respect to both its inner and outer peripheral edges. As thus shaped, the said control-ring may be said to have an annular series of inwardly-directed rounded peaks or apices 18 each of which is located circumferentially about midway between a pair of outwardly-directed rounded peaks 0r apices l9 also forming-an annular series, with each peak or formed such for instance, as brass; bronze or" aluminum.

As thus mounted, the controlering b1. is-firmly* supported without employing" integralf. magnetic: spoke which are apt to causea lockein tendency" with the permanent magnet.. Hlor. itsequivalent. and thus interfere with desirable self-starting characteristics.

The mounting-plate 20abov referred to is, in

turn, rigidly mOunted-Onthehub-Z-L of a drivepinion 22= The hub 2i,together.withitsintegral driveepinion 22', is, in turn, .rigid1y mounted upon atshaft: 23 formed ateachof itsrrespective oppositeends with.one.oftwo similar trunnions24- 2A.. The-said trunnions may be supported for rotationdn any suitable manner such, for instance, asinzthe. movement-plates ofaclock or other instrument.

The drive-pinion 22. above. referred to. is, designedandadapted-to be meshed into by a drivegear (not shown) orother. suitable drive device, propelled. by. at clock-spring or other suitable sourceof. power so as to. tend to rotate the unit comprising theparts. I tors inclusive in either direction, though preferably in the direction of the-arrow in Fig. l.

As.wi1l.-be observedby reference to Fig. 1, the pole-salients, l il.d. both have a dimension, in a direction. radially of the control-ring ll which exceeds the width of the. serpentin magnetic track provided, bythe said control-ring,v so that wheni either. theinner. or outer apices I3-0r, I9 come into. registry therewith, the said'pole-salients I '4I4 will overlap the track. Whilethe width of either pole-salient Hi in comparison to the widthof. the track must be as just explained to accomplish self -starting,it is equally.- imperativefor the. achievement of the self-starting. feature thatltheiwidth of. the pole salients is smaller than; the radial distance between the; outermost and innermostv edges. of. successive outer and, inner apexportions, respectively, of the track, and greater. than. the radial distance between the outermost andinnermost edges of successive in-.- ner. and outer. apex. portions, respectively, of the tracli. The instant. invention solves-theproblem 'offself-startinga magnetic escapementoi which the innermost and outermost. edges of? the outer and inner apex portions orthe wavy trackontlie escape member are outside and inside, respectivel'y; of a' median circle of the wavytrack. These limitations are demonstratedin Fig; 4A, in which"- the i'nnermost and outermost edges a. 'arid b ofthe-outerand inner apex portions l9 and i8; respectively, of the: track are-shown as lying: outside: and. inside, respectively; of the mediamcirole e: Fig: 4-A.furthen ShOWSithat'. the pole salient mihasgatwidth W which: is: smaller than the radial distance; W between: the: outermost; and-1 innermost. edges j: and g: of; successive outer. amhinner. apex portions I 9 and. I 8; ,respectively,, of the-v trackqandg larger. than: theradial distance; W between the: outermost and innermost-edges-b and aJof. successive inner, andouter apex portions 18 and IQ, respectively, of the track.

Th permanent magnet ID is magnetized to such an extent that the flux flowing between its two pole-salients l4l4 (respectively of opposite polarities) will. be such. aSutO. give a; magnetic lock-in: or coupling-eifect with the control-ring l'l, all for purposes as will hereinafter appear.

It may now be assumed that the vibratable permanent magnet I0 is at rest as shown in Fig. qrfi and th'at'rotating force is now applied to the unit comprising the elements I! to 24 inclusive, to turnrthe samerelative to the pole-salients i l-l 4. Hsthecontrol-ring: 11 starts to rotate, the polesalients; Hie-14:; which are still in their repose position. (Fig: 4A), will have initial movement to the left .as. the, nearest inner apex portion l8 of the track approaches. The initial motion of the poles-.salients from their repose position will be very slight, but will be increased gradually in oppositedirections until .the,-full-. desired amplitude isreached, whereupomthe said pole-salientswill track. substantially, with the serpentine form; of the-track and the control-ring-(together. with the parts connected thereto) will remain in step with the vibrations of the; magnetic unit comprising the .elements 4 e :to l Einclusive.

By. having the-control-ring IIor. its equivalent substantially freeof inwardly-projectingmagnetic spokesor. thev like and by having the.po1esalientsil t. l i ofthe magnet I dexceedthewidth of" the; control-ring, thesaid. control-ring is enabled to initiate the vibration .of the magnet l [I with. a progressively-increasing amplitude; until the full. desired. amplitude isreached. In this manner, one of-v the mainuncertainties of; prior escapements of. the present basic character is overcome andself-startingis assured, ,followed by a. magnetic lock-in .between the-magnet l0. and the..-c0ntr01.-ring; H such as tormaintainthe said control-ring. in correct time. relationship with respect to the tuning-fork efiect of the-saidv-ibrating permanentmagnet.

It.is.to be borne in mindin this connection that the. energy applied. to. the drive-pinion 22 oritsrequivalent; must-not .be in. an amount which will cause the control-ring I! to breakits magneticinterlock with the pole-salients. Ill-ll or their. equivalent.

The showing of Figs. 5 and 6 g In thestructure of..Figs..5 and6, there is:em. ployed a vibrating. magnetic-member which. is not. itself. a. permanent magnet: rather than a permanent. magnet magnetic-member as in the showing of Figs. 1 to 4 inclusive. 7

The structureshown includes a-vibratingmagnetic-membenor -unit: which includes a flexible reedzfi-i and a. pair or complemental pole-salients 2l2'l carried thereby. The said1p0le1-salient's may, be formed OffiSOfill-iI'OIIiOIilJhG like while:the said reedv .25 tmay be; formed. of: Phosphor-bronze, beryllium copper, or other suitable springyrmarterial; The, said reed is rigidly,- secured at its end remote-frcm. the pole-salients; H 2]; .to: a fixed1 upport. 28; At? its end. remote; from; the

support 28, the reed 26 185 bifurcatedito; provide it; with two laterally-spacedeapart; parallel side arms, 29-4 torthe. outer: end of each off which is brazed or otherwise rigidly attached one ofithe aforesaid pole-salients 2l2 1 For the" purpose ofcausi'ng' magnetic flux to flow. through: and between. the: nonpermanent magnet; pole-salients. 2L4 I; there-is employeda Li-shapedpermanentimagnet 3,0:having1-it -tcoms plemental arms respectively located closely adjacent but slightly spaced from the respective outer ends of the said pole-salients 2'|2| as is shown in Fig. 6.

The permanent magnet 30 above referred to may be formed of any one of the well known ferrous alloys capable of retaining magnetism and capable of imparting such magnetism to the polesalients 2'|2|. The said magnet may be fixed in any suitable manner to an instrument structure.

The respective inner ends of the pole-salients 21-21 of the reed 26 are spaced from each other sufficiently to permit the rotation therebetween of a control-ring generally designated by the reference character 3| and preferably formed of soft iron or other suitable magnetic material of a nonpermanent-magnet character. The said control-ring has a serpentine or substantially sinusoidal configuration in a circumferential direction, similar to the control-ring previously described.

The control-ring 3|, therefore, includes inwardly-directed peaks 32 and outwardly-directed peaks 33 respectively similar to the peaks I8 and I9 before described, save that each of the inner peaks 32 is formed with an inwardly-directed integral coupling-lug 34 of very small dimensions, which tightly fit into complemental notches formed in the outer peripheral edge of a mounting-plate 35, as is indicated in Fig. 5. The coupling-lugs 34 serve to mechanically connect the control-ring 3| to the mounting-plate 35 without-however, providing magnetic salients of such magnitude as would materially interfere with the self-starting characteristics of the device.

The mounting-plate 35 may be conveniently formed of brass, bronze, aluminum or other relatively-nonmagnetic material as compared to the material from which the control-ring 3] is formed. The said mounting-plate is rigidly mounted upon the hub 36 of a drive-pinion 31 similar to the drive-pinion 22 previously referred to. The hub 36, the drive-pinion 31 and the unit comprising the mounting-plate 35 and controlring 3|, are rigidly mounted upon a, shaft 38 similar to the shaft 23 before described. The said shaft is provided at its respective opposite ends with trunnions 39-39.

The pole-salients 21-21 of the reed 26 preferably have an extent in a direction toward and away from the shaft 38 which is greater than the width of the control-ring 3| at the peaks 32 and 33, and while the said pole-salients are not in themselves of permanent-magnet material, they will, in efiect, be constantly polarized by the adjacent permanent magnet 30.

Now, when turning force is applied to the unit comprising the element 3| to 39 inclusive, the control-ring 3| will initiate the vibration of the reed 26 at first with a relatively-small amplitude and then ultimately to its full designed amplitude. whereupon the control-ring 3| will remain in step with the timed vibrations of the said reed in a manner similar to that described in connection with the showing of Figs. 1 to 4 inclusive.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the, appended claims are intended to be embraced therein.

What is claimed is:

1. In a timekeeping magnetic escapement havmg a rotary escape member and an oscillatory member, the combination of an endless wavy magnetic band-like element disposed on said escape member concentrically thereof and forming a track thereon; and a polar element on said oscillatory member, one of said elements being permanently magnetized and magnetically coupled with the other element, said track element having inner and outer apex portions disposed alternately on the inside and outside, respectively, of a circle at substantially equal distances therefrom so that the innermost and outermost edges of said outer and inner apex portions, respectively, are outside and inside said circle, respectively, and said apex portions are curved substantially as the apices of a sine wave, and said polar element being of a width, radially of said escape member, which is smaller than the radial distance between the outermost and innermost edges of successive outer and inner apex portions, respectively, and greater than the radial distance between the outermost and innermost edges of successive inner and outer apex portions, respectively.

2. The combination in a timekeeping magnetic escapement as set forth in claim 1, in which the width of said polar element comes much closer to the radial distance between the outer and inner edges of successive outer and inner apex portions, respectively, than to the radial distance between the outer and inner edges of successive inner and outer apex portions, respectively.

3. The combination in a timekeeping magnetic escapement as set forth in claim 1, in which said track element is of substantially uniform band Width throughout and shaped similar to a sine wave.

4. The combination in a timekeeping magnetic escapement as set forth in claim 1, in which the dimension of said polar element, measured circumferentially of said escape member, is several times smaller than said width thereof.

MABEL T. NICHOLS, Emecutna: of the estate of Malcolm P. Nichols,

deceased.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Baker Sept. 29, 1931 Straumann Apr. 10, 1945 Number Number

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