US2616298A - Escapement mechanism - Google Patents

Description

Nov. 4, 1952 c. F. CLIFFORD ESCAPEMENT MECHANISM 2 SHEETS-SHEET 1 Filed March 26, 1947 1952 c. F. CLIFFORD ESCAPEMENT MECHANISM 2 SHEETS-SHEET 2 Filed March 26, 1947 Patented Nov. 4, 1952 UNITED STATES PATENT OFFICE ESCAPEMENT MECHANISM Application March 26, 1947, Serial No. 737,279 In Great Britain April 18, 1939 Section 1, Public Law 690, August 8, 1946 Patent expires April 18, 1959 18 Claims.

This invention relates to magnetic escapement mechanism suitable for example for a time piece, and has for its object a simplified and improved construction of mechanism.

According to the invention the improved magnetic escapement mechanism consists of complementary relatively oscillating and rotating members on one of which there is at least one polar formation and on the other of which there is provided a wavy magnetic path which in shape is substantially the locus of the geometric projection of the said polar formation of the other member upon it during relative oscillation and rotation and in which either or both of the two members is or are permanently magnetised whereby torque applied to the rotary member impulses the relative oscillatory movement and produces escapement by causing the polar formation to follow the said wavy path while magnetically locked thereto.

According to one embodiment of the invention, the improved escapement mechanism comprises two relatively movable parts, one part embodying a wavy path having inclined portions between its apices and made of magnetically conductive material, and the other part embodying at least one magnetised element having at least one pole adapted to follow said wavy path, means for mounting at least one of the parts so as to provide relative rotary and oscillatory movement so that the said pole of the magnetised element may travel along the said wavy path, means for giving the oscillatory part a natural frequency of oscillation and means for applying a rotary torque to the rotatable part, whereby the speed of relative rotation is controlled by the said natural frequency of oscillation and the applied torque impulses the oscillatory part to maintain oscillation.

In a preferred construction, one member oscillates and the other member rotates and carries the continuous wavy element.

For example, the escapement mechanism could comprise a magnetic element or complementary magnetic elements, one at least of which is a pendulum movable relatively, in a predetermined path, and providing a magnetic flux path in air moving along such predetermined path and a magnetic conductor of wave form constituting the face of a rotatable member such as a disc or cylinder and arranged to rotate in the path of movement of the said magnetic fiux, so that the axis of the wave crosses the said path and the parts lock magnetically therewith so that oscillation of the one permits rotation of the other.

In the accompanying drawings:

Fig. 1 is a perspective view of one example of an escapement mechanism made in accordance with the invention;

Fig. 1A shows a modification of the mechanism shown in Fig. 1;

Fig. 2 is a perspective illustration of a second form of escapement mechanism made in accordance with the invention;

Figs. 3 and 4 are front and side diagrammatic views of a third form of the invention;

Fig. 5 shows a modification of the form shown in Figs. 3 and 4;

Fig. 6 is a perspective view showing a fourth form of the invention;

Fig. 7 is a perspective view showing a fifth form of the invention;

Fig. 8 is a perspective view showing a modification of the mechanism of Fig. 6;

Fig. 9 is a perspective view showing a sixth modification of the invention;

9A is a theoretical diagram associated with Figs. 10 and 10A are diagrammatic plan and section showing a further modification;

Fig. 11 is a fragmentary view of an alternative conisltruction for a permanently magnetised wavy pa In one example of the invention shown in Fig. l, the escapement mechanism comprises a pen.- dulum a suspended on a knife-edge fulcrum b and incorporating a block 0 of non-magnetic material in which is embedded a magnetic conductor d of continuous wave-like form, which at its inner periphery is substantially a sine curve of eight complete cycles inscribed on an imaginary cylinder. Such conductor 11 is made from an annular or washer-like disc of mild steel pressed into a wave form. A star-shaped magnet e is rotatably mounted within the said imaginary cylinder so that its axis is coaxial therewith when the pendulum is at its central position and has eight poles'e', e of alternating N and S polarity so that in any working position of the pendulum such poles coincide simultaneously with corresponding points on each cycle of the wavy path of the conductor d. This star-shaped magnet e is arranged to be driven by spring or weight or other suitable means so as to rotate inside the said imaginary cylinder and is prevented from turning until the pendulum oscillates by reason of the magnetic lock eifect between the poles and the Wavy path of the conductor. In view of the angularity of the pendulum in its movement the shape of the wavy inner edge of the conductor is made such that the amplitude of the undulations is smaller near the fulcrum and increases proportionally with the distance from the fulcrum. This variation is a refinement which is not essential in all cases owing to the elasticity of the magnetic coupling.

In operation, rotation of the star magnet will be controlled by the periodicity of the pendulum, the spokes of the former tracing out the sine waves on the oscillating imaginary cylinder and thus escaping i. e. rotating slowly under the control of the pendulum. If the wave form of the conductor is a true sine wave and if the amplitude of oscillation of the pendulum is precisely the same as the amplitude of such wave, then the rotation of the star wheel e'will be substantially of uniform velocity. If the amplitude of oscillation of the pendulum is slightly greater as it may be, there will be a decrease in velocity of rotation at each reversal of movement of the pendulum. The escapement action is mechanically frictionless, free from wear and silent, and the small power applied to the magnetic conductor d by the star Wheel will smoothly stimulate the oscillation of the pendulum, by impulsing the same in each direction of movement whilst the inclined portion of the wavy magnetic conductor is being traversed whilst any tendency to over-stimulating such oscillation is counteracted by increase of magnetic losses proportional with over-amplitude of oscillation, which losses would operate to reduce the amplitude of oscillation to correspond substantially with that of the defined wavy path.

As shown diagrammatically in section in Fig. 1A the imaginary cylindrical formation of the conductor d is given an arcuate axis d so that the poles of the star-shaped magnet e are in all positions the same distance from the conductor to give a substantially uniform air gap.

In another example of the invention as shown in Fig. 2, a hollow stationary cylinder ofmagnetic wire I is provided, such wire having the same sine wave form. The wire cylinder is shown for convenience mounted in a shell f of non-magnetic material. 'Within the cylinder on a driven spindle gis mounted a bar magnet assembly consisting of pieces h of permanent magnetic material attached to the ends of spring spokes h of flat section which permit oscillation in a plane in which the spindle lies as shown by the arrows 7L Obviously in principle of operation the mechanism of Fig. 2 is the same as that of the mechanism first described, as the magnet assembly will oscillate substantially according to the natural frequency of its spring mounting and its own moment of inertia, whilst turning slowly at the same time to follow the sine curve of the cylinder, which will preferably be of slightly barrel-like form so as to conform with the arouate path of the ends of the magnet.

As shown in Figs. 3 and 4 the pendulum 2' includes a box-like magnetic structure 2' having N and S pole pieces 2 2' and is suspended by a fiat spring 2' Associated with such pole'pieces is a rotor disc 9' carrying a magnetic conductor of wave form. Oscillation of the pendulum allows the rotor to turn while thepoles i 2' follow the undulations of the magnetic conductor. The principle of operation is the same as before, the pendulum being impulsed by torque applied to the rotor whilst speed of rotation of the rotor is controlled by the frequency of the pendulum.

As shown in Fig. 5, the pendulum 7c embodies a C-shaped magnet k the poles of which are magnetically locked with a conductor m of wavy form constructed in the form ofa cylinder rotatable about an axis m. In this example the wave form of the magnetic conductor embodies extensions m of the apices so that greater variation of amplitude of oscillation of the pen dulum is permitted.

As shown in Fig. 6 the escapement mechanism comprises a pair of permanent magnets n secured by opposite poles to a magnetically conductive base and to each free pole of which is attached a reed n of magnetically conductive material. The two magnets collectively form a single magnet to induce magnetic flux in the reeds. The magnetised ends of the reeds are thus magnetically locked with a wavy magnetic conductor 0 mounted on a rotor by the magnetic flux which they induce therein from the magnets. Obviously the speed of rotation of the magnetic conductor is controlled by the natural frequency of vibration of the reeds.

As shown in Fig. 7 the mechanism comprises a rotor 10 in the form of a 2-pole permanent magnet rotating within a wavy magnetic conductor q having three complete sine waves pivoted on a diameter in the medial plane thereof and having its frequency of oscillation'controlled by a balance hair spring q. As'in'the example of Figs. 1 and 2, the amplitude of the undulations of the wavy conductor are proportional to the distance from the fulcrum. The operation of the mechanism is the same" in principle, the rotor although rotating being magnetically locked to the oscillating 'wavy conductor.

As shown in Fig. 8 the mechanism comprises a hollow rectangular spring reed rto WhlCh--i$ secured a washer-like ring 1" pressed to undulating wave form within which is mounted a star-shaped rotor s the poles of which are magnetically locked to the wavy inner periphery of the magnetic conductor formed by the said ring r. In operation the vertical up and down vibration of the washer-like ring 1' allows the starshaped rotor s to escape and this latter action impulses the vibrating system and maintains the vibration.

As shown in Fig. 9 there is provided an-escapement lever t mechanically connected inthe normal way to a balance wheel u, the levercarrying a wavy magnetic conductor t, the undulations of which lie on the periphery of an-imaginary cylinder. Within the conductor t is-a star wheel 0 rotatably mountedon aspindle v and urged for rotation by any suitable means. As shown in Fig. 9A a pole "12 of the star wheel '12 is of substantial width relative to the Wavy magnetic path. The effect of such proportions is that when the pole is located at an apex as shown dotted there will be a magnetic lockwith a greater length of the wavy conductor than there will be in the intermediate position, as shown in full, and consequently there will be a reduction in the reluctance of the magnetic path between the pole and the wavy conductor and-a tendency 'to hold the lever in suchposition from which'it will initially have to be moved bythe momentum of the balance wheel on its return rotation. The oscillating balance wheel is impulsed through the lever by the magnetic lock with the poles of the star-shaped wheel'v as they follow the inclined portions of the Wavy magnetic path, as in 'all previously described examples.

As shown in Figs. and 10A adjacent, the wavy magnetic conductor w is embedded in the inner wall of a cylinder w of brass or other non-magnetic material. On the inner surface of the said cylinder are longitudinal ribs :1: in staggered arrangement which provide mechanical interference to passage of the poles except when they follow the wavy path and thus the aforesaid ribs a: mechanically obstruct rotation of the poles if they leave the magnetic path. Such mechanical obstruction would not normally occur.

As shown in Fig. 11 the wavy track Y may be of channel section and permanently magnetised so that its edges form continuous poles. Such track could be used in various ways, for example in the arrangement of Fig. l, in which case the star wheel a would not be permanently magnetised or else would have complementary ends, such as U-shaped ends which could be magnetised where a stronger magnetic lock is required with the magnetic poles provided by the magnetised edges of the path.

It will be understood that the expression pendulum is used herein generically and that the term is not limited to a gravity controlled oscillating member but includes any spring balance device such as described in the second example of the invention.

Other alternatives come within the scope of the invention besides those described. For example, an external magnet attached to the pendulum could trace out a magnetic sine wave on the external surface of a cylinder Which was spring driven. The magnets shown in the various figures, might, with advantage in some cases, be magnetised axially instead of radially.

Whilst a sine curve will give a substantially smooth or continuous escapement action, the invention is not limited thereto as the wave form may be modified if required to suit any particular conditions, without departing from the nature of the invention. The construction may also be modified in other details without departing from the nature of the invention.

In all cases magnetic parts which are subject to changing magnetic fluxes, whether changing in density or direction, are preferably made of a material of low hysteresis loss of which there are several materials known and produced for such characteristic.

What I claim is: v

1. A magnetic escapement, comprising a first member; an oscillatory member, said members being mounted for relative rotary movement; an endless wavy magnetic band-like element on one of said members forming a track thereon; a polar element on the other member; and means for inducing magnetic flux in said elements to couple them magnetically, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of a circle at substantially equal distances therefrom, and other portions connecting successive apex portions, respectively, said other portions being onopposite sides of said circle inclined to the latter and being otherwise shaped and directed so that one element will follow the other magnetically coupled element during substantially natural oscillation of said oscillatory member.

2. A magnetic escapement, comprising a rotary power-driven escape member; an oscillatory member; an endless wavy magnetic band-like element on one of said members forming a track thereon; and a polar element on the other member, one of said elements being permanently magnetised and magnetically coupled with the other element, said Wavy element having successive apex portions disposed alternately on opposite sides, respectively, of a circle at substantially equal distances therefrom, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being otherwise shaped and directed to follow said magnetically coupled polar element during substantially natural oscillation of said oscillatory member.

3. A magnetic escapement, comprising a rotary power-driven escape member; an oscillatory member; an endless wavy magnetic band-like element on one of said members forming a track thereon; and a polar element on the other member, one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of a circle at substantially equal distances therefrom, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being otherwise shaped and directed to follow said magnetically coupled polar element during substantially natural oscillation of said oscillatory member without substantial variation in reluctance.

4. A magnetic escapement, comprising a rotary power-driven escape member; an oscillatory member; an endless wavy magnetic band-like element on one of said members forming a track thereon; and a polar element on the other member, one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of a circle at substantially equal distances therefrom, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being otherwise shaped and directed to follow said polar element during substantially natural oscillation of said oscillatory member, and said members being coordinated so as to have a substantially uniform air gap between said elements in all working positions of said members.

5. A magnetic escapement, comprising a rotary power-driven escape member; an-oscillatory member; an endless, wavy magnetic band-like element on one of said members forming a track thereon; and a polar element on the other member, one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of a circle at substantially equal distances therefrom, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being curved so as to follow said magnetically coupled polar element during substantially natural oscillation of said oscillatory member.

6. A magnetic escapement, comprising a rotary power-driven escape member; a second member; a strip spring by means of which said second member is mounted on a support for oscillatory movement; an endless Wavy magnetic band-like element on one of said members forming a track thereon; and a polar element on the other member, one of said elements being permanently magnetised and magnetically coupled with the othereleinent; said wavy element having SUQCQSQ sive apex portions disposed alternately on opposite sides.,.. respectively, of a, circleat substantially equal distances therefrom, and otherportions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclinedto the latter and being other:

wise shapedand directed to follow said magneti Cally :coupled polar element during substantially natural oscillation; of said secondmember.

7. A ma n t cap ents inea ro ary power-driven escape member; an oscillatory member; an endless'wavy magnetic band-like element; on one of said members forming a track he e n a po a e men n the, he membe nd I s ne. s i nd ne gnet c flu in sa d ementstw w them-m s ally ss dr av ememhar ne uq ss ve pe r iqns. sp d"v alternately on opposite sides, respectively, ofa circle at substantially equal distances therefrom,

and other portions connectingsuccessive apex:

portions, respectively, said other portions being onopposite sides of said circle inclined to the latter and being otherwise, shaped and directed to followsaid magnetically coupled polar element during substantially natural oscillation of said oscillatorymember.

8. A magnetic escapement, comprising a rotary power-driven escape member; an oscillatory member; an endless wavy magnetic band-like element on one of said members forming a track thereon; and a polar element on the other member,

one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides,

respectively, of a circle at substantially equal distances therefrom, and other portions connect ing successive apex portions, respectively, said member; an endless Wavy magnetic band-like,

element on one of said members forming a track therenn; a polarelement on the other member, one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of a circle at substantially equal distances therefrom, and other portions connecting successive apex portions, respectively, said other p ortions being on opposite. sides of said circle inclined to the latter and being otherwise shaped and directed to follow said magnetically coupled polar element during substantially natural oscillation of said'oscillatory member; and cooperating means on said members, respectively, to obstruct-mechanically rotation of said rotary member if said polar element should swerve considerably from said track.

10. A magnetic escapement, comprising a rotary power-driven escape member; an oscillatory member, one of said members having a cylindrical surface; anendless wavy magnetic band-like element onthecylindricalsurface of said-one member forminga trackthereon; a polar element on-the other member, one ofsaid elements be e nen l me e i se a d, agn ically,

u l d,- tns hs-o her ele e t s id, ary re1em i havi u c s ve. e port ons d s osed. alternately on opposite sides, respectively, of a circle at substantially equaldistances therefrom, andother portions connecting successive apex portions respectively, said other. portions being onopposite sides of; said circle inclinegl to the, latter andbeing otherwise shaped and directed to follow said magnetically coupled polar element duringsubstantially natural oscillation. of said oscillatory member and staggered abutments on,

said cylindricalsurface of said one member be tween, successive connecting I portions, respecv lm. of saidtra k elem tqo i q me n callyreiatire ation a d. ssi si b of the ellfictivei members it aid, o ar element shou dv ervecon iderably irqm a d t a k.

1-; A ma net c ca men qin in 1 t ry ower -d iv n cape. mem er; n o s ls qry member; an endless wavy magnetic band-like elementp said rotary member forming a track thereon; and a polar element on saidoseillatory member, one of said elements being permanently mag-netised and v magnetically coupled with the other velement said wavy element having successiveap x port pnsdi pose l rn t s/.1 1 11110:

site sides, respectively, of a circle at substantially equal distances therefrom, and other portions connecti g ucc si e a ex pe ises p t v ly, s ids hsrmrt ns e n n op o i s idss sa circle inclined to thelatterand being otherwise shaped and directed to follow said. magnetically co pled polareleme i dur na ls aniia v 11st: m ci ation, of, saidosci l iqr -s b -v 12. A magnetic escapement, comprising, a rotary power-drivenlescape member; an oscillatory member; an en less a vma netie andr k lement.- n said osc aip y, em e o n a. track thereon; and. a po with the ctherelment, said wavy elementlhav ins successive pexp rt ons dis osed a ate on opposi e id slresnsctiv ly i-a ir le t qu distances therefrom, and other portions connecting successiyeapex portions, respectively, said other portions being on opposite, sides of said circleinclinedto the latter and being otherwise s ped an directe so, tha said-r0la i men will follow said magnetically conpled traclr ele he r ta y axis, f I sai es pe member; nd an endless wavy magnetic band like element on the periphery of said disc-like escapemernb er forming atracl z. thereon, one of said elements, be-

ing permanently magnetised and magnetically conpled with the otherelement, said wavy element having successive apex portion disposed alternately inwardly and outwardly of a concentriccircle or said escape-member at substantially, equal distances therefrom, and" other" screens, connecting successive apex portions; respectively, said other .portionsbe ingon opposite'rjside s of said,

circle inclined to the latte coupled polar. element during, substantially natural oscillation of said oscillatory member? 1a. A magnetieescapement,comprising a re.- tary povver edriven v clrumf-lilre escape member hay;

lar, element on said roary m m er. onel iv s d lement being er r nently magnetisedand magnetically coupled I r. and being otherwise shaped and directed tofollow said magnetically {1 st reassess, siips c;1 atti ,me "her,

having a polar element and being oscillatory in a plane parallel to the rotary axis of said escape member; and an endless wavy magnetic band- 1ike element on the peripheral surface of said drum-like escape member forming a track thereon, one of said elements being permanently magnetised and magnetically coupled with the' other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of, and being substantially equally spaced from, a circle lying in a plane at right angles to the rotary axis of said escape member, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being otherwise shaped and directed to follow said magnetically coupled polar element during substantially natural oscillation of said oscillatory member.

15. A magnetic escapement, comprising a rotary power-driven escape member having a polar element; another member oscillatory in a plane parallel to the rotary axis of said escap member and having a formation provided with an interior cylindrical surface surrounding said escape member and polar element; an endless wavy magnetic band-like element on the interior surface of said formation forming a track thereon, one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of, and being substantially equally spaced from, a circle lying in a plane at right angles to the axis of the interior cylindrical surface of said formation, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being otherwise shaped and directed so that said polar element will follow said magnetically coupled track element during substantially natural oscillation of said oscillatory member.

16. A magnetic escapement, comprising a, rotary power-driven escape member; a polar element on said escape member, said polar element being oscillatory in a plane parallel to the rotary axis of said escape member; a stationary member having an interior cylindrical surface surrounding said escape member and polar element; an endless wavy magnetic band-like element on the interior surface of said stationary member forming a track thereon, one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of, and being substantially equally spaced from, a circle lying in a plane at right angles to the axis of the interior cylindrical surface of said stationary member, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being otherwise shaped and directed so that said polar element will, during substantially natural oscillation thereof, follow said magnetically coupled track element.

17. A magnetic escapement, comprising an oscillatory member having a polar element; a r0- tary power-driven disc-like escape member; an endless Wavy magnetic band-like element on the periphery of said escape member forming a track thereon, one of said elements being permanently magnetised and magnetically coupled with the other element, said wavy element having successive apex portions disposed alternately on opposite sides, respectively, of, and being substantially equally spaced from, a, circle lying in a plane at right angles to the rotary axis of said escape member, and other portions connecting successive apex portions, respectively, said other portions being on opposite sides of said circle inclined to the latter and being otherwise shaped and directed to follow said magnetically coupled polar element during substantially natural oscillation of said oscillatory member.

18. A magnetic escapement as set forth in claim 1 wherein cooperating means are provided on said members respectively to obstruct mechanical rotation of said rotary member if one of said elements should swerve considerably from the other magnetically coupled element.

CECIL FRANK CLIFFORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 708,769 Inden Sept. 9, 1902 1,277,371 Boyle et a1 Sept. 3, 1918 1,517,008 Jones Nov. 25, 1924 1,788,065 ONeal Jan. 6, 1931 1,825,382 Baker Sept. 29, 1931 2,061,047 Schweitzer Nov. 17, 1936 2,359,656 Lurtz Oct. 3, 1944 FOREIGN PATENTS Number Country Date 690,365 France June 17, 1930

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