US2803941A - Regulating mechanism for a time keeping escapement - Google Patents

Description

Aug. 27, 1957 w. c. STILLWELL 2,803,941

REGULATING MECHANISM FOR A TIME KEEPING ESCAPEMENT Filed Sept. 22, 1954 I V N TOR William Eizllwell 2,803,941 Patented Aug. 27, 1957 REGULATING MECHANISM FOR A TIlVIE KEEPING ESCAPEMENT William C. Stillwell, Wheaton, 111., assignor to New Haven Watch and Clock Company, New Haven, Conn., a corporation of Connecticut Application September 22, 1954, Serial No. 457,583

7 Claims. (Cl. 58-113) This invention relates to an arrangement for varying the effective length of a coil spring as used in pulsing an escapement, particularly as employed in time keeping mechanism.

Impulsing of the balance wheel is'the result of the coordination of the intermittent movement of the escapement wheel as driven by a suitable source of power and the coaction of the balance wheel in its natural period as oscillated by the balance spring.

To determine the period of the balance wheel the customary hair spring is adjusted by altering the overall stiffness of the effective portion thereof. The usual method is to fix the outer coil at some point just beyond the stud pin by means of curb pins engaging the spring on both sides thereof with a pinching action. Thus, when regulation is to be accomplished the pins are moved longitudinally of the spring to a new position. In order properly to fix the effective termination of the outer coil the curb pins must abut the same very closely in which case, if no provision is made for separating the pins prior to movement and to close them following movement, undue drag will occur and the spring is easily damaged. Consequently, various arrangements have been proposed for operating the pins away from the spring at the beginning of the adjustment and subsequently re-closing the same. For example, in one specific type movement of the regulator arm occurs on pivots arranged for substantial movement in slotted holes which will inevitable result in movement of the curb pins tangentially of the spring followed by the desired separating movement radially thereof. Thus the tangential component of motion may easily damage the spring.

Ideally the curb pins should pinch the spring at all times before and after adjusting movement but should be away from the spring immediately after initiation of such movement and until the desired total adjustment has been concluded.

Accordingly, the principal object of the invention is to provide a regulator mechanism cooperative with a coil spring which is incapable of buckling the spring during its manipulation.

Another object is to provide regulating mechanism in accordance with the foregoing which includes a minimum number of parts so arranged as to occupy minimum space.

A further object resides in providing regulator mechanism having the foregoing objects in view but which maintains its selected adjustment in a positive manner.

Still another object lies in accomplishing the foregoing objectives with mechanism which is adaptable in all its essentials to the smallest movements.

Other objects will become clear from the ensuing description which, taken with the accompanying drawings, will disclose a preferred mode of carrying the invention into practice.

In this drawing:

Fig. 1 shows a front elevation of the regulating mechanism;

Fig. 2 is a side elevational view thereof;

Fig. 3 is a detail to show the curb pins and cam sector for actuating the outer pin;

Fig. 4 shows an exploded view to illustrate the several parts of the mechanism; and

Fig. 5 is a front elevational view of a novel form of coil spring capable of use with the invention to facilitate its manipulation.

In the following description I will, for clarity, illustrate the invention as applied to the customary flat hair spring although it will become apparent that the same is adaptable to other forms of hair spring capable of being adjusted by engagement of a pair of curb pins or their equivalent on both faces of a coil. Moreover, the inven-' tion is not to be regarded as limited in its application to a hair spring associated with a lever escapement or to a hair spring for a timepiece since other interval-measuring organizations may utilize a hair spring or its equivalent and the same may be embodied in timers'not strictly classifiable as a watch or clock.

Broadly regarded the invention, in one aspect, involves the provision of a fixed curb pin and a radially-movable curb pin, the pins being relatively separable to allow adjustment along the length of the spring without binding, but movable jointly for shifting to a new position along the spring. Both curb pins are carried on an index member for joint angular movement about the center of the balance staff and the outer curb member is carried on an arm having a cam follower. A sector having a serrated peripheral section, constituting a plurality of cams, cooperates with the follower in order that angular movement of the index member will cause the follower to rise and fall on the teeth thus to separate the curb pins coincidentally with joint angular movement thereof. Thus no tangential movement of the curb pin is possible without a concurrent radial movement and separation of the pins. In another aspect the invention contemplates forming at least that portion of the outer coil of the spring over which the curb pins have their total excursion into a true circular are, at least in its median position, whereby to assure that any adjusting movement is effective simply to change the overall stiffness of the spring but not the shape of its convolutions.

Turning now to the drawing, the balance wheel, of any conventional type, is indicated at 10 and the balance staff at 11. The adjacent portion of the usual support plate 12 is bored at 13 to receive a pressed-in bushing 14 having a flange l5. Interposed between the flange 15 and plate 12 is a regulator member or index 18 in the form of a plate, preferably of uniform thickness having a circular aperture 21 capable of rotation on the body of the bushing 14. It is to be understood that, in assembly, the bushing 14 is pressed home with reservation for movement of the index 18. In order to avoid critical spacing at this stage the boundary of the aperture 21 may be slit, as at 22, and the edges thereof deformed axially to insure appropriate friction of the index as respects the plate 12 and flange 15.

Index 18 is provided with a toothed portion 23 in mesh with a pinion 24 carried on a staif 25 which extends to an accessible position for manual rotation and consequent movement of the index during regulation.

Index 18 carries an arm 31 pivoted at 32 and urged constantly clockwise by a suitable spring 33. At its opposite extremity there is provided a through cylindrical pin 37 one end, 38, of which acts as a cam follower, and the other end, 39, of which serves as the outer curb pin.

Index 1.8 includes a bent-over portion 41 including a transversely arcuate hump 42 constituting the inner curb pin. The balance spring 45 is shown with its outermost convolution 46 interposed between the curb pins, and a projection 47 is provided to prevent accidental dislodgment of the spring from its position between the curb pins and to prevent inadvertent entry of another convolution therebetween, and as is customary in this art. The spring is shown fixed to the collet at 51 and to the stud 52 in the usual manner. In this case the stud 52 is conveniently carried on the fixed arm 53 of the relatively fixed cam 54 now to be described.

The pivot for the balance staff is in the form of a stud 61 including a shank 62 and head 63, the former having a conical depression constituting the bearing. The shank 62 is a press fit in a bore 66 of the bushing 14 and is inserted therein in such degree as to provide a running fit for the balance staff. The flange 15 and head 63 are so designed that when assembled there exists axial space therebetween to receive rotatably the fixed cam plate 54 and a wave or similar washer 67 to provide friction thereagainst. While the cam plate 54- is described and claimed herein as fixed it will be understood that such term is to be regarded relatively to the index 18 since, actually, the cam plate 54. is capable of being forcibly shifted for initial positioning but, once so set, is incapable of being shifted by manipulation of the index 18 and the consequent camming action to be detailed.

Cam plate 54 is substantially a quadrant having a plurality of cams 71 on its periphery. Although the cams 71 may take any form capable of actuating the follower 38, with intermittent rise and fall action and with it the curb pin 39 we have shown the same as comprising a plurality of serrations having an included angle of substantially 90. Thus, when the curb pins are closed on the spring the follower will be almost seated between a pair of adjacent teeth and when the pins are to be separated to permit movement thereof along the direction of the coil 46 to a new position without impingement upon the coil a sloping surface of one or the other of such teeth will act in a camming manner to dislodge the follower 38 and its thereto-attached arm 31 and pin 39 radially outwardly. Such action may occur upon either clockwise or counter-clockwise rotation of the index 13, the follower 38 moving therewith and against the serrations 71. Stated otherwise, regulation may be accomplished over an angle corresponding to the full angular extent of the several serrations 71 with a fineness of adjustment corresponding to the circular pitch of the teeth '71. By utilizing a follower 38 of sufficiently small diameter the pitch may be made correspondingly fine and, in fact, sufficiently close to enable proper regulation of any movement or mechanism in which variation of balance spring stiffness is acceptable as a mode of regulation. For example, in one practical embodiment of the invention the serrations are sawtooth in form, have a pitch of 0.008 r and a height of 0.008" and are arranged to cooperate with a cylindrical follower having a diameter of 0.010. Obviously the relative positioning and dimensions of the curb pin 42 will be such that the outer coil of the spring is fully fixed in its adjusted position under urging of the spring 33, and in which position the follower 38 is between a pair of teeth 71 but not fully seated thereupon. In other words the radially innermost position of the curb pin 39 is fixed by the balance spring and its abutment, in turn, against the curb pin 38, and not by seating of the follower 38 on the faces of a pair of teeth.

As an additional precaution that the circular movement of the curb pins about the center C will not shift the outer coil out of predetermined form I have provided a novel configuration of the outer coil. Thus, referring to Fig. 5 the outer coil is offset at a point 31 approximately half way of its extent and, from that point to the customary offset 82 adjacent the stud 52, is conformed to an arc of a true circle. Consequently the circular paths traversed by the curb pins during regulation are concentric with at least that portion of the outer coil with which such travel is coextensive and consequently, any possibly injurious radial force component which might otherwise subject the spring to spurious deformation is thereby eliminated.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limted thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

I claim:

1. Regulator mechanism for a time keeping device which includes a coil spring for oscillation of a balance Wheel comprising a pair of curb pins respectively disposed on opposite faces of a coil of the spring for altering the overall stiffness of the effective portion thereof, a fixed member having an arcuate periphery concentric with the curve of said coil, said periphery having a plurality of closely-spaced identical cam surfaces, a movable member for carrying one curb pin, a cam follower coactive with said cam surfaces and the other curb pin both carried by said movable member, said follower when actuated moving said movable curb pin away from and into abutment with said coil, and means for moving said member to traverse said follower over said cam surface.

2. Regulator mechanism for a time keeping device which includes a coil spring for oscillation of a balance wheel comprising a pair of curb pins respectively disposed on opposite faces of a coil of the spring for altering the overall stiffness of the effective portion thereof, a cam member having a plurality of cam surfaces disposed in a curve concentric with said coil, a follower member, means for moving said cam member and follower relative to one another for intermittent movement of said follower, one of said curb pins being mounted on said moving means and the other of said curb pins being mounted on said follower whereby intermittent movement of the follower in response to cam action alternately shifts said other of said curb pins to and away from coil-abutting position to provide a selective plurality of curbpin positions.

3. Regulation mechanism for a time keeping device which includes a coil spring for oscillation of a balance wheel comprising a fixed member having a peripheral portion including a plurality of identical cam surfaces disposed along a curved path, a member movable on a curved path parallel to said first curved path, a cam follower supported on said movable member, a movable curb pin cooperative with a second curb pin variably determining the overall stiffness of the effective portion of the sprin Said movable curb pin being mounted on said follower for movement therewith whereby relative displacement between said cam surfaces and follower provide corresponding displacement of said movable curb pin in directions alternately against and away from the spring together with movement along the spring, said second curb pin being mounted on said movable member for movement parallel to said first curved path.

4. Regulator mechanism for a time keeping device which includes a coil spring for oscillation of a balance wheel comprising a fixed member having a peripheral portion including a plurality of identical cam surfaces disposed along a curved path, a support movable on a curved path parallel to said first curved path, an arm pivotally mounted on said support, a cam follower carried on said arm and adapted to rock said arm as said follower is actuated by said cam seriatim, a curb pin carried by said support, a second curb pin carried by said arm, said curb pins being arranged for variably determining the overall stiffness of the effective portion of the spring, whereby interaction of said follower and cams is effective to cause relative separation of said curb pins while the pins as a unit are traversed along the length of the spring.

5. Regulator mechanism for a time keeping device which includes a coil spring for oscillation of a balance wheel, said spring being fixed at its outer terminus com prising a first curb pin and a second curb pin respectively adapted to engage each of the faces of a coil of the spring, means for moving said curb pins jointly along the length of the coil while retaining the outer terminus of the spring fixed and means active concurrently with such lengthwise movement for intermittently separating said pins from coil-engaging position to coil-clearing position during continued lengthwise movement.

6. Regulator mechanism in accordance with claim 5 wherein said pin separating means comprises a plurality of fixed cam surfaces and a follower coactive therewith, said follower being operatively connected to at least one of said curb pins, and wherein said curb pin moving means also carries said follower.

7. Regulator mechanism for a time keeping device which includes a coil spring for oscillation of a balance wheel comprising a member pivoted for adjusting movement about the axis of the balance wheel, an arm pivoted at one end on said member, a fixed member having a circular serrated portion on a margin thereof, the pitch line of the serrations lying on a circle having said axis as a center, said serrations constituting a plurality of identical camming surfaces, a follower cooperative with said cams and carried on the free end of said arm for reciprocation of said arm as said follower is moved pursuant to pivotal movement of said member, a first curb pin mounted on said pivoted member and a second curb pin carried on said free end of said arm for reciprocating movement with said follower, and means for biasing said follower into operative relation with said serrations.

References Cited in the file of this patent UNITED STATES PATENTS 2,209,172 Putman July 23, 1940 2,637,970 Kocher May 12, 1953 FOREIGN PATENTS 256,274 Switzerland Feb. 16, 1949 287,611 Switzerland Apr. 1, 1953

Images