US2948108A - Overwind preventer for timepiece - Google Patents

Description

Aug.` 9, 1960 F. MEYER OVERWIND PREVENTER FOR TIMEPIECE 2 Sheets-Sheet 1 Filed July 26. 1955 13211810P5B 9 'I 3 A P t Aug- 9, 1950 F. MEYER 2,948,108

ovsRwINn PREVENTER FOR TIMEPIECE Filed July 2s. 1955 2 sheets-sheet 2 FIG# 29 0 1 Z 3 4 5 6 lNvi-:NToR

BYFriedrich Neger ATTORN EY spring.

OVERWIND PREVENTER FOR TIMEPIECE Friedrich Meyer, Grenchen, Switzerland, assignor to Felsa S.A., Grenchen, Switzerland Filed July 26, 1955, Ser. No. 524,343 Claims priority, application Switzerland Sept. 14, 1954 7 Claims. (Cl. 58-83) My invention relates to timepiece movements and particularly to avmovement with an automatic winding mechanism including a lockable oscillating weight.

As is well known to those skilled in the art in timepieces (watches, clocks, etc.) with automatic winding medhanisms, provisions must be made to prevent the overwinding of the motor spring.

.'In almost all of the prior devices for limiting the winding of timepieces, constructions are used depending upon friction produced by a spring. However, the effect of such springs largely depends on outer, uncontrollable inlluences, such as changes in climate and in temperature affecting the degree of winding of the motor sprmg.

Also snap mechanisms for a positive locking of the oscillating weight have been used, these mechanisms being under the constraint both of the motor spring and of a counterspring, whereby on an excess of the force of the motor spring beyond the force of the counterspring, a locking member snaps into engagement with the oscillating weight. However, these countersprings relax with time as they are permanently loaded by the motor sprmg.

It has already been endeavored to avoid the use of friction springs and of countersprings by controlling the device for locking the oscillating Weight by means of-a differential gear in operating connection with the 4barrel and the barrel arbor in such 'a Way that-this device stops the oscillating weight after a prescribed winding rotation of the motor spring and releases the weight after a prescribed unwinding rotation of the motor In ,the known solutions of this type, the differential gearis to bend a spring in both directions of rotation of a driven member to such an extent that the said spring releases a snap actionl locking lever to be swung by-the saidl spring, the said lever being to stopand lock the oscillating Weightv in tfhe one direction of rotation of the said driven member and to release the said weight in the other-direction of rotation .of Ithe said driven member. 'Ilhe said spring permanently coupled with the locking lever, under the effect of the said driven member, rests on both directions of rotation of the said driven member against opposite sides of a stop positionedl withfin the axis of rotation of the locking lever, so that, when a certain deflection of the spring is reached, the spring also the tension of the motor spring, cannot be kept constant, particularly due to theelongation or reduction of the long spring under the eifect of temperature varations. Y fln addition, the change in the direction of deformation increases the stress of the spring, so that the :limitation of the tension obtained is, vit is true, more inaccurate rthan with the .friction 4springs and counterlonged hub `6 of the sun wheel 5.

springs, but not, however, with the required precision. Particularly, a reliable operation is still wanted due to thev length of the spring and to itsresting on a small stop. Besides, assembling of this device is not easy.

An object of the invention is to overcome these drawbacks. For this purpose, a rigid rocking member, subjected to the action of a spring and susceptible of being rocked in both directions of rotation by a control Wheel driven by the differential gear, is operatively connected, in the vicinity of both its end positions, by means of a lag coupling, with :a member adapted to lock the oscillating Weight. This device is not only very simple, but its several parts can be manufactured so as to have a very accurate shape and undergo no prejudicial deformation. In addition, these parts do not rest against sensitive supports. Applicant has thus created for the iirst time a device which permits keeping the tension of the motor spring constant to such an extent that the motive power of the watch is similar to that of -a clock actuated by a weight.

`Other objects and features of the invention will be apparent as the following description proceeds, reference being had to the accompanying drawings, illustrating by way of example, some embodiments of my invention, and wherein Fig. l is a schematic plan View of the parts of the movement which are necessary for an understanding of the invention.

lFig. 2 is a section along the line A-BC-D-EF of Figure l.

' Fig. 3 is a diagram showing the variation of .the motive power of the motor spring in function of the rotation of the barrel arbor.

Fig. 4 illustrates another embodiment of the cooperating rocking and locking members.

Fig. 5 is a plan view of a further example for the cooperating rocking and locking members, and

Fig. 6 is a still further embodiment of the rocking and locking members. f

lFig. 7 is a plan view l'at a reduced scale of a modified oscillating weight. i

Fig. 8 is a side view, partially in section, of the oscillating weight shown in Figure '7.

The diferential gear controlling the locking device comprises a transmission wheel 2 having a cylindrical toothing 3 and a contrate toothing 4. The wheel 2 is rigidly connected to a sleeve 1 loosely mounted on a pin 16 iixed to the pillar-plate 17. On the sleeve 1 is freely mounted a sun Wheel 5 having a long hub 6. The

sun wheel 5 meshes with a planet wheel 7 rotatably mounted on a second transmission wheel 8. The planet wheel 7 also engages with the contrate toothing 4 of the Wheel 2. The wheel i8 is freely mounted on the pro- The hub 6 carries a driven Wheel 9 which meshes with a control wheel 10 having a lug I18. The wheel 10 is pivoted in the cen- `ter of the movement by means of :a sleeve 39 on the pinion 13 and the wheel 8 remain at rest and the barrel 11 rotates the control Wheel I1t), through the intermediary of the differential gear, in the clockwise -direction of Fig. 1. When the motor spring is wound by `means of the oscillating weight 15 pivoted at the center of. the movement through the intermediary of meansnot illustrated, the Vdriving of the differential gear by the pinion 13 prevails over that produced by the pinion 12, and the barrel arbor 14 rotates the control wheel 10, through the intermediary of the dilferential gear, in .the counterclockwise direction of Fig. 1.

In the vicinity of the barrel arbor 14 a rigid, cranked, disc-shaped rocking member 20 is pivoted on the pillarplate 17 forming part of the frame of the watch movement by means of a pin 119. The member 20 has on the side near the `control wheel a fork-shaped portion provided with two prongs 211 and 210 between which the lug 18 passes in the manner described later on, this lug 18 coming into contact alternatively with one or the other of the prongs 21, 210 for rocking the member 20. On the side opposite to the prongs 21, 210, the member 20 has a notch 22 which is engaged by one end of a yoke-shaped leaf-spring 23, preferably pretensioned, the otherend of which is pivot-ed as at 24 on the pillarplate 17 so that the spring 23 can also swing on rocking the member 20. The spring 23 is adapted to rock the member 20 suddenly as soon as the lug 18 has brought the member '20 by means of one of its pron- gs 21, 210 into a rocking position explained below. The rocking member 20 has a notch 25 engaged by the lug 26 of a disc-shaped locking member 28 pivoted on the pillarplate 17 by means of a screw Z7. The member 28 has a .sinuous spring member 29 carrying at its free end a locking pin 30 passing through an opening 42 of 4the pillar-plate 17, this locking pin being adapted to engage in the manner `described below one of the notches 31 provided on the oscillating weight so as to lock the latter.

The notch l25 and the lug 26 form together a lag or slack coupling means which operates only when the member has passed beyond the rocking position, in order to actuate the locking member 28. Beforehand, the lug 26 and the wall of the notch 25 do not contact each other, and in order that, in this condition of noncontact, the locking member 28 is prevented from rotating inopportunely, it is held by a weak jumperV 3-2 fixed as at 33 to the pillar-plate 17.

The differential gear and the members 20 and 28 are held in the axial direction by .the dial-holder 34 which is xed to the pillar-plate *17 by means of the screws 35 and 27.

The shown and described device operates as follows:

With reference to Fig. `l the locking pin 30 is out of engagement with the oscillating weight 15. The latter can therefore oscillate, winds the motor spring and rotates the cont-rol wheel 10 and the lug 18 in the counterclockwise direction of Fig. 1 through the intermediary of the barrel larbor and the differential gear. The lug 18 engages the prong 21 of the Afork-shaped portion of the rocking member 20 and rocks the latter in the clockwise direction of Fig. 1. The line of action 36 of the force exerted by the spring 23 onto the member 20 still passes on the side of the axis of rotation of the member 20 which is opposite to the locking member 28. The spring 23 thus exerts onto the member Z0 a moment directed in the counterclockwise direction, so that the said member 20 is still slowly driven by the prong 21, no contact occurring between the wall of the notch and the lug 26 of the locking member 28, the latter being prevented from rotating inopportunely by the jumper 312. When the member 20 further rotates in the clockwise direction under the action of the lug 18, there is a moment at which the line of action 36 passes beyond the axis of rotation of the member 20 and arrives between this axis and the locking member 28. The spring 23 thenexerts a moment directed in the clockwise direction onto the member 20 and very quickly rocks the latter in this direction, so that the prong 21 leaves `the lug 18 and the wall portion 37 of the notch 25 strikes against the lug 26 yand suddenly rocks the locking member 28 in the counterclockwise'direction of Fig. 1, The

inner surface 38 of the oscillating weight 15, which is adapted to cooperate with the locking pin 30, has near its ends inclined surfaces 44. When the locking member 28 is rocked in the -counterclockwise direction, two cases may occur: Either the weight 15 is just out of reach of the pin 30 and when it 4further oscillates, the inclined surfaces 44, when arriving within reach of the pin 30, act onto the latter and repel it against the elastic force to which it is subjected; or the pin 30 directly bears against the inner surface 38 of the weight 15 under the action of the spring '23. If none of the notches 31 is at this moment within-reach of the pin 30, the surface 38 first slides on the pin 30 until the latter, under the action of the spring 23, can `fall into a notch 311 and thus lock the oscillating weight `15. Therefore, the control wheel 10 first remains unmoved and then begins to turn in the clockwise direction of Fig. l under the laction of the differential gear due to -t-he unwinding of the motor spring. The shock of the pin 30 against the surface 38 is `damped by the spring member 29. The pin 30 is retained in its locking position by the spring 23. Outer `influences i.e. other than those produced by the rocking member 20 cannot cause the pin 30 to leave its locking position. The way of the pin 30, limited by the opening 42, is designed in such a manner that when for instance the member 28 is turned =by hand in the clockwise direction it cannot turn thelmember 20 from its locking position up toits rocking position, so that the member 28, under the action -of the spring 23, immediately returns into its locking position. Inthis position the pin 30 does not necessarily bear against the bottom of a notch 31. It can bear against the wall of the opening 42 when it is engaged in the notch 31.

When the motor spring has been unw'ound by -a certain amount, the lug '18 which moves in the clockwise direction strikes against the prong 210 of the member 20` and slowly rocks the latter in the counterclockwise direction of Fig. l as Ithe line of action 36 rst -lies between the locking mem-ber l28 and the -axis of rotation of the member 20 and, therefore, the moment exerted by the spring 23 acts in a `direction opposed to the driving action of the lug 18. The wall portion 37 of the notch 25 leaves the llug 26 and the locking member 28 is maintained in its place by the jumper 32. When the member 20 further rotates in the counterclockwise vdi-rection under the action of the lug 18, there is a moment, depending upon the unwinding condition of the motor spring, lat which the 'line of action 36 passes beyond the laxis of rotation of the member v20 and arrives onto the side opposite to the member 28 with respect to this axis. Now, the spring .23 exerts on the member 20 a rocking moment directed in the counterclockwise `direction `and rocks this member in this direction, so that the prong 210 leaves the lug 18 and the wall portion v43 of the notch 25 strikes against the lug 26 of the locking member 28. The member 28 the pin 30 of which was upto now engaged in a notch 31 of the oscillating weight 15 suddenly rocks in the clockwise direction of Fig. 1 until the pin 30 abuts against the wall of the opening 42. The pin 30 which, in this positiontoo, is retained by the `spr-ing 23 releases the weight 15 which begins to oscillate, so that the differential gear rotates the control wheel10 with the lug 18 in the counterclockwise direction. In this non-locking position too, 'the Ilocking member 28 cannot be brought into the lock- "ing position under the action of outer inuences i.e. other than those produced by the rocking member 20, for instance by being turned by hand in the counterclockwise direction since upon such a movement in the counterclockwise direction the pin 30 would abut against the Wall of the opening 42 or against the oscillating Weight `15 before the locking member 28 has brought the member 20 from its non-locking position up to its rocking position. When the member 28 would be released, the spring 23 would, therefore, bring back the latter in the `clockwise `direction into vits non-locking position. After some time the lug 18 strikes upon its movement in the counterclockwise direction against the prong 21 and rocks the member 20 in the clockwise direction so that the wal-1 portion 43 of the notch 25 leaves the lug Z6, whereas the locking member 28 is retained by the jumper 32 out of engagement with the weight 15, so that the position of the several parts of the device is again that shown in Fig. 1 and the described cycle can start again. When the watch is wound by hand, the lu-g 18 can pass in front of the prong 21 beyond the position shown in Fig. 1. When the motor spring is unwound and the lug 18 has rocked the member 20 by acting on the prong 210, the lug 18 passes in front of the said prong 210 if the Watch is left unmoved yand therefore the self-winding device does not operate.

It results from the preceding that the winding and unwinding rotations of the motor spring are determined in the most precise manner by the two rocking positions, which remain always the same, of the rocking member 20, the line of action 36 of the force exerted by the spring 23 passing on one side or the other of the axis of rotation of the member 20 depending upon the direction of rotation of the latter. Since the member 20 is formed by a rigid disc and in addition the distance between both prongs 21 and 210 `does not undergo any variation during the lifetime of the watch, these rocking positions and, therefore, the winding and unwinding rotations of the motor spring do not undergo any undesired variation. Moreover the engagement between the lug 18 and the prongs 21, 210 as well as between the wall of the notch 25 and the lug 26 remains 4always perfectly guaranteed. If

for instance the two rocking positions of the member 20 are chosen in such a manner that after an tmwinding of the motor spring up to the 4:7 revolution or so, the oscillating weight 15 lbe released and that after a winding of the spring up to the 5 revolution, the weight 15 be again locked, the `diagram of Fig. 3 will show that, on the Watch being worn, the motor spring is permanently in a condition in which the motive power is nearly constant. The diagram of Fig. 3 illustrates the vari-ation of the motive power of the motor spring, expressed in cm. gr., in function of the number of winding revolutions of the said spring. Any production of useless energy is thus avoided. The motor spring and the force-transmitting wheels are spared and the lifetime of the self-vvinding device is considerably increased. The conventional running reserve of 45 hours can be assured with the greatest accuracy. This is obtained by means of very simple parts which can be manufactured with a great precision.

When the movement is wound by hand, the motor spring is completely wound long before the lug 18, which rotates in the counterclockwise direction of Fig. 1, abuts against the wheel 9. Similarly when the 'watch is at rest and therefore is not wound automatically, the motor spring is already unwound long before the lug 18, which rotates in the clockwise direction of Fig. 1, abuts against the wheel 9.

Instead of the yoke-shaped spring 23 it is also possible to use a coil spring or another type of spring which is pivoted at one of its ends and is preferably pretensioned. The notch 25 might Ialso be provided on the locking member 28 and the lug 26 on the rocking member 20 (Fig. 4). The lagging coupling might also be constituted by an opening 54 in one of the members 20, 28 and by a pin 55 of the other member engaged in this opening (Fig. 5). Instead of Ithe jumper 32 `any other retaining means for the locking member 28 may be provided. The prongs 21, 210 might also be provided on the control wheel 10 and the lug 18 on the rocking member 20 (Fig. 6).

In the modication shown in Figs. 7 and 8 the osci1lat ing weight has a supporting plate 45 extending over somewhat less than half a circle and being integral with an outer thicker rim 46. However, the rim 46 might be rigidly connected to the plate 45. The oscillating weight is pivoted in Aa known manner (not shown) in the watch movement by means of the bore 47. At the ends 48 of the rim 46 and on the side opposite to the plate 45 by a ring segment 49 of light metal, for instance of aluminium, is Ifixed by means of screws 50, the thickness of segment 49 being as small as possible, and the width equal to that of the front face of the rim 46. The weight of the ring segment 49 is chosen so small that the center of gravity of the whole oscillating weight formed of the parts 45, 46 and 49, is shifted to such a little extent towards the center of rotation of the oscillating weight with respect to ythe center of gravity of the combined parts 45 and 46, that this shifting has practically no influence on the winding effects of the weight.

The circular inner surface 51 of the rim 46 forms with the inner surface 52 ofthe ring segment 49 la surface extending over 360 which has in horizontal projection a circular shape between the notches 53 acting as Ilocking means. The notches 53 are distributed at spaced intervals on both surfaces 51 and 52 and are adapted to cooperate with the locking pin 30.

When the locking pin 30 is ready for locking the oscila lating weight, i.e. when it bears against the cylindrical surface 51, 52 between the notches 53, this surface, on the weight oscillating, can slide on the pin 30 without having to repel the latter, against the elastic force acting thereon, transversally to the trajectory of the oscillating weight, as all the points of the surface 51, 52 are at the same distance from the axis of rotation of the weight. Although the motor spring is strongly wound, the oscillating weight can therefore still move until one ofthe notches 53 comes opposite the locking pin 30 and the latter may fall into this notch and thus lock the weight. When the motor spring is unwound by a certain amount as eX- plained above the pin 30 goes out of the notch 53 and ceases to be in Contact with the surface 51, 52.

Instead of several notches 53, a single notch might be provided. For reducing the weight of the ring segment 49, this member might also be made narrower Ithan the rim 46 or lrecesses might be provided therein.

While I have shownand described some embodiments of my novel device, I do not wish to unnecessarily limit the scope of my invention, but reserve the right to make such modifications and rearrangements of the several parts that may come within the purview of the accompanying claims.

What I claim is:

1. In an overwind preventer for a timepiece comprising oscillating weight winding mechanism including a barrel and a barrel arbor, a frame, a differential gear mounted on said frame and operably connected between' the barrel and the barrel arbor, a control wheel, the control wheel meshing with the diiferential gear, a lug for thecontrol wheel, the lug being in driving connection through the control wheel with said differential gear to be alternately driven in opposite directions, a rocking member loosely mounted on said frame, two prongs positioned on the rocking member at a distance from each other to alternately cooperate with said lug, the rocking member adapted to swing from one end position to another and means forming la wall of a notch in the rocking member displaced at about right angles from said prongs, a stirrup-shaped spring pivoted on said frame and engaging said rocking member at a position opposite to said prongs to alternately press said prongs against said lug to alternately swing said rocking member in opposite directions, a rocking member rockingly mounted on said frame and having a lug entering said notch while being at a distance from the wall of said notch except in the end positions of said rocking disk, a curved spring member integral with said locking member, a locking pin carried by the free end of said spring member, means forming a wall of a hole in said frame receiving said locking pin to limit the movement thereof, and a holder spring mounted on said frame and engaging said locking member to prevent undesired movement of same.

2. In an overwind preventer for a timepiece comprising oscillating weight winding mechanism lincluding a barrel and a barrel arbor, a frame, a differential gear mounted on said frame and operably connected between the barrel and the barrel arbor, a control wheel, the control wheel meshing with the differential gear, a lug for the control wheel, the lug being in driving connection through the control wheel with said differential gear to be alternately driven in opposite directions, a rocking member loosely mounted von said frame, two prongs positioned on the rocking member at a distance from each other to alternately cooperate with said lug, and means forming a wall of a notch in the rocking member, a spring pivoted on said frame and engaging said rocking member' to alternately press said prongs `against said lug and to alternately swing said rocking member in `opposite directions, a spring-held locking member for the oscillating Weight rockingly mounted on said frame and having a lug entering said notch while being at a distance from the wall of said notch except in the end positions of said rocking member.

3. In an overwind preventer for a timepiece comprising oscillating weight winding mechanism including a barrel and a barrel arbor, a frame, a differential gear mounted on said frame and operably connected between the barrel and the barrel arbor, control means `in driving connection with said differential gear to be alternately driven in opposite directions, a rocking member loosely mounted on said frame to alternately cooperate with said control means, lost motion-coupling means on said rocking member, a spring pivoted on said fname and engaging said rocking member to alternately press said rocking member against said control means in opposite directions and to alternate swing said rocking member 4in opposite directions, a spring-held locking member for the oscillating weight rockingly mounted on said frame and having lost motion-coupling means separated from the lost motion-coupling means of said rocking member except in the end positions of said rocking member.

4. In an overwind preventer for a timepiece comprising oscillating weight winding mechanism including a barrel and a barrel arbor, a frame, a differential gear mounted on said frame and operably connected between the barrel and the barrelarbor, control means in driving connection with said diierential gear to be alternately driven in oposite directions, a rocking member loosely mounted on said frame to alternately cooperate with said control means, a spring mounted on said frame and engaging said rocking member to alternately press said rocking member against said control means in opposite directions and to alternately and suddenly swing said rocking member in opposite directions, a locking member for the oscillating weight, rockingly mounted on said frame, a coupling including female coupling means on the one of said two members, and male coupling means on the other of said two members, said male coupling means entering said female coupling means while being at a distance from the wall of said female coupling means except in the end positions of said rocking member.

5. In an overwind preventer as claimed in claim 4, said female coupling means of said coupling being a notch and said maleV coupling means of said coupling being a lug.

6. In an overwind preventer as claimed in claim 4,

said female coupling means of said coupling being a circular hole and said male coupling means of said coupling being a pin. A 7. In an overwind preventer as claimed in claim 4, means forming Aa hole in said frame and a locking pin on said locking member, said locking pin entering said hole for limiting the movement of the locking member so that it is prevented from passing from one end position to the other end position under inuences other than those produced by the rocking member.

References Cited in the file of this patent UNITED STATES PATENTS 332,023 von Der Heydt Dec. s, 1885 2,709,332 Meyer May 3l, 1955 FOREIGN PATENTS 75,789 Switzerland Sept. 17, 1917 '155,515 Switzerland Sept. 1 6, 1932 713,036 France Aug. l0, 1931

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