Patent Application
20190196409
This application claims priority from European Patent Application No. 17209994.7 filed on Dec. 22, 2017, the entire disclosure of which is hereby incorporated herein by reference.
The invention relates to the field of clockmaking. It concerns, more precisely, a repeater mechanism for a timepiece with a striking mechanism, the expression “timepiece” designating preferably a watch (wrist or fob), but likewise being able to designate a pendulum clock or even a clock.
The repeater mechanism (currently simply named repeater) has the function, when actuated by the user (or wearer) exerting at any moment pressure on a push button, of striking the hour indicated at this moment by the hands of the timepiece.
The repeater is a clockmaking complication of extreme refinement, mastery of which does credit to the clockmaker who is at the origin thereof. Formerly intended for allowing the time to be known in darkness, the repeater today equips watches of great, or even very great value.
There are several types of repeater. In Les Montres Compliquées (Ed. Simonin, fifth edition, 2013), F. Lecoultre enumerates five thereof, but distinguishes essentially two (the most common):
In the absence of action by the wearer, the hour part is in its resting position.
Displacement of the push button causes a forced rotation of the striking mechanism barrel, the hour part being itself displaced towards its reading position in opposition to the spring.
Release of the push button is accompanied by return of the hour part towards its resting position. On the way, the hour part meshes (directly or indirectly) with a hammer striking a gong a number of times equal to the number of hours read on the snail and proportional to the angular course covered by the hour part between its two positions (reading, resting).
In the repeater, termed old-fashioned, coupling of the barrel to the hour part was effected by means of a rocker and a chain, as explained by F. Lecoultre (op. cit., pp. 68-69 and FIG. 19, Table 17).
This coupling has, in modern repeaters, been replaced by a rack and a wheel train, as explained likewise by F. Lecoultre (op. cit., pp. 73-74). Two opposing springs are provided: a barrel spring which forces the hour part towards its resting position, and an hour spring which forces it towards its reading position. Actuation of the spring by the wearer, whilst arming the barrel spring, frees the hour spring which returns the hour part towards its reading position. Releasing the spring frees, conversely, the barrel spring which returns the hour part towards its resting position (in opposition to the hour spring), whilst the striking mechanism of the hour is unwound.
This type of repeater does not give complete satisfaction because the motor torque exerted by the barrel spring is not constant. The result, during operation, is variations in the loads to which the hour part is subjected, which can generate in the latter mechanical fatigue cycles, conducive to cracking thereof.
Recently, an entirely new repeater mechanism has been proposed, which is fitted to the Breguet model 7087 “Tradition” watch and in which the wheel train is replaced by a chain transmission.
This transmission should not be confused with the chain of the old-fashioned repeater mentioned above because it functions inversely.
More precisely, in this repeater, the barrel comprises:
The chain is hooked, by a proximal end, on the pulley and, by a distal end, on the hour part. In the absence of action by the wearer on the push button, the barrel spring tightens the chain which keeps the hour part in its resting position. Action of the wearer on a push button causes the forced rotation of the barrel shaft, which frees the chain and therefore the hour part, which is returned towards its reading position by the hour spring.
When the wearer releases the push button, the barrel spring, the motor torque of which exerted on the barrel shaft is greater than the resistant torque exerted by the hour spring on the hour part, returns the latter towards its resting position. On the way, the hour is struck.
The reading (and the striking) of the quarters and/or of the minutes follows the same principle, with a quarter snail (respectively minute) and a quarter part (respectively minute) bearing a quarter feeler-spindle (respectively minute) which is able to come, in a reading position, in contact with the quarter snail (respectively minute).
This mechanism has an advantage in terms of space and assembly. In fact, the chain, which makes the mechanical connection between the barrel and the hour part on the other hand, makes it possible to position them at a distance one from the other. It is thus possible, whatever the positioning of the hour part in the watch middle, to place the barrel nearest the push button, which avoids having to resort to complex lever returns, to the benefit of the operational reliability of the watch.
However, this chain mechanism has a disadvantage which results from the fact that it operates on an all-or-nothing basis, i.e. whatever the hour to be struck, the wearer fully depresses the push button. Consequently, the actuation of the barrel causes complete unwinding of the chain, whatever the angular course of the hour part. In the case (alone) where the hour to be read is 12h59 (which corresponds to the maximum course of the hour parts (if necessary the quarters) and the minutes, the chain remains tensioned. But in all other cases, the angular course of these parts is not at maximum and the remaining course of the chain (beyond that which it adopts in the reading position of the hour part) causes slackening thereof, and floating thereof.
Upon releasing the barrel, the barrel spring does not encounter any resistant force until the chain is again abruptly tensioned between it and the hour spring. The result is a peak in the tension force to which the chain is subjected, which can cause shearing fatigue in the axes of the connecting links of the chain or in its fixing point on the hour part.
Consequently, a first object, in a repeater mechanism with a chain as described above, is to minimise the mechanical fatigue of the mobile parts (in particular of the chain).
A second object is, more precisely, to smooth out the forces generated in the chain by the action of the barrel spring.
There is proposed, firstly, a repeater mechanism for a timepiece with a striking mechanism, which comprises:
Consequently, the chain is always tensioned, whatever the hour to be struck. The result is a reduction in the mechanical fatigue which the chain (with the assembly of mobile components) undergoes in the course of time, to the benefit of the operational reliability (and the operational life) of the mechanism.
Secondly, there is proposed a watch equipped with a middle and such a repeater mechanism, mounted in the middle.
Various additional features, presented below, can be provided, alone or in combination.
Hence, the pulley spring is preferably a spiral spring, an internal end of which is integral with the ratchet, and an external end of which is integral with the pulley.
The pulley advantageously integrates a limit stop, and the ratchet integrates a tooth which is applied against the limit stop as long as the chain exerts a traction force on the pulley, and which is offset angularly therefrom as soon as the traction force exerted on the chain by the hour part in the reading position is cancelled out.
The repeater mechanism can furthermore comprise:
In this case, the watch is advantageously equipped, apart from the middle and the repeater mechanism, with a push button mounted in translation on the middle between a disarmed position in which the push button does not exert a motor torque on the rack, and an armed position in which the push button exerts a motor torque on the rack which causes rotation of the barrel shaft via the striking mechanism train.
The striking mechanism train comprises, for example, an input pinion which meshes with the toothed sector of the rack, and an output pinion which is integral in rotation with the barrel shaft.
The striking mechanism train advantageously comprises a multiplier pinion which is integral in rotation with the input pinion and meshes with the output pinion.
The repeater mechanism can furthermore comprise a locking pawl which is in engagement with a toothed crown with asymmetrical toothing carried by the barrel drum.
The repeater mechanism can likewise be provided with a return bearing on which the chain runs between the striking mechanism barrel and the hour part.
Other objects and advantages of the invention will appear in light of the description of an embodiment, given hereafter, with reference to the attached drawings in which:
In
The watch 1 comprises a clock movement designed to indicate at least the hours and the minutes. The movement comprises a plate intended to be accommodated in the internal volume 3 defined by the middle 2, being fixed there.
The movement comprises furthermore various functional components brought together by sub-assemblies. When a sub-assembly has a different function from displaying the hours, the minutes and, if necessary, the seconds, it is termed “complication”.
Hence, the timepiece (i.e. the watch 1) which is illustrated has a striking mechanism, and comprises, for the purposes of striking the current hour, a repeater mechanism, likewise termed “repeater complication” or, more simply (and as used hereafter), “repeater” 5.
The repeater 5 comprises, firstly, at least one hour snail 6. This snail 6 is mounted in rotation on an axis A1. It has a general spiral shape and comprises, on its periphery, a succession of twelve angular sectors of decreasing distances from the axis A1.
The hour snail 6 is integral in rotation with an hour star 7 which comprises twelve pointed teeth.
In the illustrated example, the repeater 5 likewise comprises a quarter snail 8, mounted in rotation about an axis A2. The quarter snail 8 comprises four angular sectors of decreasing distances from the axis A2, separated by smooth adjoining faces.
The repeater 5 comprises furthermore a minute snail 9, integral in rotation with the quarter snail 8 and which comprises four branches which are notched over their circumference, separated by smooth adjoining faces which extend in the extension of the adjoining faces of the quarter snail 8.
The quarter snail 8 bears, in the vicinity of its periphery, a finger which, upon each turn, comes to mesh with a tooth of the hour star 7 in order to turn the latter by a twelfth of a turn representing an advance of one hour.
The repeater 5 comprises, secondly, an hour part 10, mounted in rotation about an axis A3 and bearing an hour feeler-spindle 11.
The hour part 10 is mounted in rotation about its axis A3 between:
As illustrated in
The hour part 10 comprises an exterior arm 17 provided with an hour rack 18 comprising twelve projecting teeth. During return of the hour part 10 from its reading position to its resting position, the hour rack 18 actuates an hour hammer (not illustrated) which comes to strike an hour gong tuned to a predetermined acoustic frequency, possibly amplified by a structural part of the watch 1 (e.g. the middle 2). The hour hammer strikes the hour gong a number of times (between one and twelve), equal to the number of teeth of the rack 18 which have actuated it during return of the hour part 10 from its reading position to its resting position.
The repeater 5 comprises, fourthly, an hour spring 19 which returns the hour part 10 towards its reading position. In the illustrated example, the hour spring 19 is a spiral spring. It is advantageously fixed on the hour part 10 by an internal end 20, and on an axis integral with the plate by an external end 21.
The repeater 5 comprises, in the example illustrated in
The repeater comprises furthermore, in the example illustrated in
The repeater 5 likewise comprises a quarter spring 26 which returns the quarter part 22 towards its reading position, and a minute spring 27 which returns the minute part 24 towards its reading position.
The minute part 24 is provided, on an exterior arm 28, with a minute rack 29 comprising fourteen projecting teeth. During return of the minute part 24 from its reading position to its resting position, the minute rack 29 actuates a minute hammer (not illustrated) which comes to strike a minute gong tuned to a predetermined acoustic frequency which is different (e.g. lower) than the acoustic frequency of the hour gong. The minute hammer strikes the minute gong a number of times (between zero and fourteen), equal to the number of teeth of the minute rack 29 which have actuated it during return of the minute part 24 from its reading position to its resting position.
The quarter part 22 is provided, on an exterior arm 30, with a quarter rack 31 comprising three series of projecting teeth. During return of the quarter part 22 from its reading position to its resting position, the quarter rack 31 actuates, almost simultaneously, the hour hammer and the minute hammer in order to generate a close sequence of two notes. The hour hammer and the minute hammer strike their respective gongs a number of times (between zero and three), equal to the number of series of teeth of the quarter rack 31 which have actuated them during return of the quarter part 22 from its reading position to its resting position.
As is seen in
The repeater 5 comprises, fifthly, a striking mechanism barrel 32.
The striking mechanism barrel 32 is mounted in rotation about an axis A4 of the barrel. The striking mechanism barrel 32 is a sub-assembly which comprises several components, amongst which:
The barrel shaft 33, the barrel drum 34 and the pulley 38 are all three mounted in rotation about the axis A4 of the barrel. These components are described in detail further on.
According to a preferred embodiment, the pulley defines a peripheral cam path 39.
The repeater 5 comprises, sixthly, a chain 40 which is able to be wound up partially on the pulley 38. More precisely, the chain is able to be wound up on the cam path 39. The chain 40 is hooked, by a proximal end 41, on the pulley 38 and, by a distal end 42, on the hour part 10.
The chain 40 comprises a plurality of links 43 which are articulated one relative to the other. The link 43 situated at the proximal end 41 of the chain 40 is fixed on a pin 44 which is integral with the pulley 38. The link 43 situated at the distal end 42 of the chain 40 is, per se, fixed on a pin (not visible) which is integral with the exterior arm 17 of the hour part 10.
According to one embodiment illustrated in
As seen in
According to one embodiment illustrated in
As seen in
According to one embodiment illustrated in the drawings, the barrel shaft 32 comprises a pivot 48 and an arbor 49 (which can be mounted on the pivot 48 or formed with the latter in monobloc form) on which the barrel drum 34 is mounted. The arbor 49 is provided externally with a hook 50 to which the internal end 36 of the barrel spring 35 is fixed.
The pivot 48 has, at one end opposite the arbor 49, a head 51 with a square section.
The barrel drum 34 comprises a base 52 pierced, in its centre, by a hole 53 through which the barrel drum 34 is threaded (with clearance) on the arbor 49, and a skirt 54 which projects axially from the base 52, on the periphery of the latter. The external end 37 of the barrel spring 35 is fixed on the skirt 54, e.g. by means of an excess thickness 55 formed on the barrel spring 35 (possibly in the form of a mounted and welded blade) housed in a notch 56 which is hollowed into the internal wall of the skirt 54.
As illustrated in
According to a preferred embodiment illustrated in
The striking mechanism barrel 32 comprises a pulley spring 60, operating in torsion and interposed between the ratchet 47 and the pulley 38, and which exerts, on the latter, a resistant torque which keeps the chain 40 under tension when the ratchet 47 is uncoupled in rotation from the pulley 48.
According to a preferred embodiment illustrated in
In the illustrated example, the internal end 61 of the pulley spring 60 is shaped as a first stud which is fitted in a complementary notch 63 formed in the ratchet 47 (see the detail circles at the top and to the right in
As illustrated in
The tooth 59 of the ratchet 47 is applied against the limit stop 65 as long as the chain 40 exerts a traction force on the pulley 38. Inversely, the tooth 59 of the ratchet is offset angularly from the limit stop 65 as soon as the traction force exerted on the chain 40 by the hour part 10 in the reading position is cancelled out.
As represented in
The rack 66 has the shape of a hook. The rack 66 is provided with a boring 69 by which it is mounted on its axis A5. On both sides of this boring 69, the rack 66 comprises a lever 70 bearing at its end a button 71 (which, in the illustrated example, is mounted and driven into a hole formed in the end of the lever 70), and a bent arm 72 in which the toothed sector 67 is formed.
The rack 66 is mounted in rotation about its axis A5 between a resting position (
According to one embodiment illustrated in
In the illustrated example, the striking mechanism train 68 comprises furthermore a multiplier pinion 75 (partially opened up in
The rack 66 and the pinions 73, 74, and 75 of the striking mechanism train 68 are dimensioned and fitted so that the total angular course of the rack 66 between its resting position and complete armed position corresponds to an almost complete turn of the pulley 38, causing almost total unwinding of the chain 40 from the cam path 39.
In the illustrated example, the rack 66 comprises twelve teeth (nine and a half of which are used during the course of the rack 66 between the resting position and the complete armed position); the input pinion 73 comprises fourteen teeth; the multiplier pinion 75 comprises twenty-two teeth and the output pinion 74 comprises fifteen teeth. Consequently, the transmission ratio between the rack 66 and the output pinion (i.e. the barrel shaft 33, and therefore the ratchet 47) is 0.99. In other words, in the total course of the rack 66 (between its resting position and its complete armed position) corresponds to one rotation of the ratchet by 358°.
As seen in the detail inset at the bottom on the right in
According to a preferred embodiment, the limit stop 76, although mounted locked by being driven in, can tolerate an angular clearance so as to form an eccentric which allows the clockmaker to control precisely the angular position of the rack 66 (and therefore the corresponding angular position of the ratchet 47) at the end of travel into its complete armed position.
As illustrated in
The repeater 5 operates in the following manner, it being understood that the barrel drum 34, retained by the locking ratchet 58, can turn about the axis A4 of the barrel only in the direction indicated by the arrow X1 (
The rack 66 is permanently returned towards its resting position by the torsion force of the barrel spring 35 which is wound by force on the axis 33 of the barrel.
As long as no pressure is exerted on the push button 77, the rack 66 occupies its resting position. As the external end 37 of the barrel spring 35 is fixed, since it is integral with the barrel drum 34, itself retained by the ratchet 58 in engagement with the toothed crown 57, the barrel spring 35 exerts on the barrel shaft 33 a motor torque in the direction of the arrow X1 (
This traction force, much greater than the resistant force produced on the chain 40 (via the hour part 10 to which the latter is attached) by the resistant torque generated by the hour spring 19, tends to displace the hour part 10 in rotation in the direction indicated by the arrow Z1 in
The repeater 5 is actuated by the wearer by means of pressure exerted radially on the push button 77, in the direction of the centre of the middle 2 (white arrow, at the bottom in
The push button 77 comes to press on the button 71 which it displaces by making the rack 66 pivot about its axis A5, via the lever 70, in the direction indicated in
The rack 66, which meshes with the input pinion 73, causes the latter to rotate in the direction indicated in
The barrel shaft 33, integral with the output pinion 74 and the ratchet 47, drives the latter in the direction of rotation of the output pinion 74 (arrow F5,
During this time, the chain 40 is pulled (arrow Y2,
F6,
For any read hour other than 12h59, the hour part 10 reaches its reading position before the rack 66 reaches its complete armed position. Then, the hour part 10 no longer exerts traction on the chain 40 which for its part no longer exerts a motor torque on the pulley 38. However, moved by the rack 66 via the striking mechanism train 68, the ratchet 47 follows its rotation in the direction indicated by the arrow F5, so that the tooth 59 is offset angularly from the limit stop 65. As the pulley spring 60 retains, whatever the angular position relative to the ratchet 47 and the pulley 38, a torque reserve, it continues to exert a resistant torque (arrow F8,
When the read hour is 12h59, the hour part 10 reaches its reading position at the same time as the rack 66 reaches its complete armed position. The limit stop 65 of the pulley 38 remains in contact with the tooth 59 of the ratchet 47 over their entire angular course, and the chain 40 remains permanently tensioned.
However, the pressure on the push button 77 is maintained until the rack 66 has reached its complete armed position when the limit stop 76 comes to abut against the input pinion 73 (
When the push-button 77 is released, the barrel spring 35, the external end 37 of which has remained (and remains) fixed, returns the barrel shaft 33 (and therefore the ratchet 47) towards its initial position. When the read hour is 12h59, the tooth 59 is applied against the limit stop 65 and the ratchet 47 immediately sets the pulley 38 in its rotation. For any read hour other than 12h59, the ratchet 47 firstly pivots about the axis A4 of the barrel without actuating the pulley 38 until the tooth 59 comes in contact with the limit stop 65. Then, the pulley 38 and the ratchet 47 are again integral in rotation, and are jointly returned towards their initial position (arrow X1,
Having reached its resting position, the hour part 10 locks the chain 40 which for its part locks the rotation of the pulley 38 which locks the rotation of the ratchet 47, which locks the rotation of the barrel shaft 33 and with it the striking mechanism train 68 and the rack 66. The push button 77, pushed back by the rack 66 via the button, regains, for its part, its resting position. The repeater 5 is thus locked.
During the entire course accompanying the release of the push button 77, the hour part 10, the quarter part 22 and the minute part 24 have, together (and in the manner explained above), struck the displayed hour.
The advantages obtained by the repeater 5 are decisive: therefore when the push button 77 functions on an all-or-nothing basis, and when it is pushed fully down whatever the hour to be struck, the chain 40 remains permanently retained under tension. Apart from the aesthetic aspect (the floating of the chain might be considered as a fault by the demanding amateur), the stress peaks undergone by the chain 40 are avoided, to the benefit of its lifespan—and that of the assembly of the repeater 5. In the end, the mechanical fatigue undergone by the chain 40 and the assembly of mobile parts of the repeater 5 is limited.
| Number | Date | Country | Kind |
|---|---|---|---|
| 17209994.7 | Dec 2017 | EP | regional |
