EP4343449A1 - Power reserve indicator - Google Patents

Abstract

The present invention relates to a power reserve display mechanism (1) of a timepiece powered by a mechanical energy source (2), comprising an input mobile provided with a driven drive element in a first direction when arming and in a second direction opposite to said first direction when disarming said energy source (2), said drive element being arranged to receive an information value (V) relating to said power reserve, and transmit it to a rotating display member (8) capable of moving on a first angular sector (S1) corresponding to a first angular range (P1) predefined between a minimum value (Vmin) and a maximum display value (Vmax), said power reserve display mechanism (1) being characterized in that said mobile display member (8) is integral in rotation with the hub (60) of a mobile d display (6), which display mobile (6) further comprising a rim (61) provided with partial teeth (61A) extending only over part of its periphery and which is arranged to mesh with said element drive, said serge (61) and said hub (60) being connected to one another via at least one elastic arm (62).

Description

Technical field of the invention

The present invention relates to the field of watchmaking, and in particular to a display device for the power reserve of a wristwatch.

State of the art

We know, in the state of the art, devices making it possible to indicate, at any time, to the user information on the quantity of energy stored in the barrel of a movement, in order to determine whether the movement is close to stopping or its maximum winding level, and thus anticipate the stopping of the watch.

In most of these devices, safety mechanisms are also proposed in order to allow the display mechanism to disengage in relation to the driving force exerted by the movement barrel, particularly at the end of the stroke, in order to avoid that the display needle is still rotated when it has already come to rest on a pin. Such solutions often use friction mechanisms to achieve the clutch release.

Alternatively, as described in the patent CH711236 , the clutch can be released using elastic elements rather than friction; nevertheless, the solution disclosed in this patent only allows disengagement in the direction of disarming, not arming. The patent application EP3699694 similarly uses a coupling between a display element and a movement driving element using an elastic element, one of the ends of which can move in a loop. However, this solution here again only allows the coupling between the display element and the drive element according to a predefined angular swing, depending on the dimensioning of the angular sector available in the loop.

Furthermore, display solutions are known which use differential systems which make it possible to recover on the one hand information on the winding of the barrel spring, and on the other hand information on its disarming in order to take an average and thus improve the display precision thanks to the output indication of a more reliable stored energy level.

This type of mechanism has been known since the 1950s, and is described in particular in the reference work by B.Humbert “ B.Humbert's self-winding Swiss watch, 1955 ") .

More recent solutions, such as that described for example in the patent EP1139182B1 , use such a differential mechanism for the power take-off of the movement and also propose a safety system based on a coupling between a drive wheel and a display wheel using an elastic element, one end of which is secured to a pin inserted in a loop arranged radially in the drive wheel, and whose movement is conditioned by a cam integral in rotation with a drive pinion coaxial with this drive wheel. This disengagement system, however, only seems to be effective when disarming, but not necessarily when arming. In fact, it is enough to calibrate the length of the loop in relation to the shape of the cam so that it is sufficient not to cause blocking at the end of the stroke, which is relatively easy since at the end of the stroke the remaining torque exerted by the barrel is low. However, when arming, there may be the risk of the pin blocking at the distal end of the loop, the radial clearance being generally dimensioned so as to prevent the pin from passing over the loop. the other side of the cam on which no stable rest position is possible.

The improvement proposed by the solution described in the international application WO2005/085963 of the same applicant aims precisely to solve this problem when cocking by reintroducing a friction mechanism in parallel with the elastic device provided for uncocking.

There is therefore a need for a solution free from these known limitations in terms of disengagement, in particular when arming.

Summary of the invention

An aim of the present invention is to provide a new safety mechanism for a power reserve display device devoid of friction means, and which is more robust than the usual mechanisms using elastic means.

These goals are achieved, according to the invention, thanks to the characteristics of the main claim, and in particular thanks to a power reserve display mechanism of a timepiece powered by a mechanical energy source, comprising a input mobile provided with a drive element driven in a first direction when arming and in an opposite direction when disarming the energy source, the drive element being arranged to receive a value d information relating to the current power reserve, and transmit it to a rotating movable display member capable of moving over a first angular sector corresponding to a first predefined angular range between a minimum value and a maximum display value, the power reserve display mechanism being characterized in that the mobile display member is integral in rotation with the hub of a display mobile, which display mobile further comprising a rim provided with teeth partial extending only over part of its periphery and which is arranged to mesh with the driving element, the serge and the hub being connected to each other via at least one elastic arm .

An advantage of the proposed solution is to obtain a more robust safety mechanism than those using entirely elastic means, that is to say those being completely devoid of friction means, by making it possible to disengage indefinitely whatever the direction of movement. of the display needle. In this way, any risk of breakage of one or more components of the transmission chain is avoided in a particularly effective and durable manner, without risk both when winding and uncocking the barrel supplying the movement with energy.

Another advantage of the proposed solution is to gain in compactness for the proposed security mechanism, and in particular in height, since such mechanism is now produced on a single stage, in the plane of the display mobile, without no longer requiring a dedicated connecting element interposed for example between an indicator mobile and a drive wheel.

Yet another advantage of the proposed solution is to simplify the provision of a safety mechanism to the power reserve display mechanism thanks to a reduced number of components. Indeed, the safety mechanism is completely integrated into the display mobile in the form of an “elastic wheel”, which facilitates assembly operations and thus optimizes production costs by reducing the time required for assembly.

According to a preferred embodiment for the power reserve display mechanism according to the invention, the hub is also provided with a loop extending over a first angular sector corresponding to the first predefined angular range, and a pin fixed limitation is housed in the loop and can abut on either side of it for the respective display of the minimum display value and the maximum display value.

In this way, the safety mechanism is produced in a particularly simple manner in the plane of the display wheel, the location of the pin defining a fixed reference to determine the positioning of the mechanism, not only making it possible to give it a simplified structure compared to those using friction means, but also to further simplify manufacturing and assembly operations.

According to an even more preferential embodiment, the power reserve display mechanism according to the invention, the partial teeth of the serge extend over a second angular sector strictly included in the first angular sector.

In this way, the second angular sector on which the partial teeth of the display mobile are arranged only extends over a second angular range strictly less than that of the first angular display range, and an additional clearance formed by the differential angular sector at each end makes it possible to minimize the tension forces on the arms each time a disengagement is generated. Thus, the efficiency and durability of the system are further optimized.

According to another preferred embodiment for the power reserve display mechanism according to the invention, the partial teeth of the rim are formed by external peripheral teeth of the display mobile.

Such a configuration makes it possible to minimize the overall thickness of the security mechanism by making the gear plane vis-à-vis the drive pinion, or more generally any drive element of the display mechanism, directly in the plane of the display mobile.

According to an even more preferential embodiment for the power reserve display mechanism according to the invention, the rim is also provided with an external peripheral bead extending over a third angular sector corresponding to a third angular range, the third angular sector being located strictly outside the second angular sector.

Such a configuration makes it possible to achieve, on the one hand, better balancing of the display mobile, by compensating for the absence of teeth with a counterweight and thus avoids any tendency to lean with respect to the gear plane. Furthermore, the addition of the bead makes it possible to constitute at the same time an anti-shock device by limiting the movement of the display mobile produced in the form of an elastic wheel in a housing of slightly larger diameter. Indeed, the bead makes it possible to compensate not only in weight, but also in volume in the radial direction, and therefore simulates a wheel which has retained all of its peripheral teeth, which limits its level of movement compared to a adjacent wall if an impact causes it to collide at this location.

According to a particularly preferred embodiment for the power reserve display mechanism according to the invention, the number of elastic arms is between 2 and 5.

Such a configuration is advantageous for maximizing the stability of the display mobile in the plane.

According to a particularly preferred embodiment for the power reserve display mechanism according to the invention, the total number of turns is between 4 and 8.

Such a configuration makes it possible to optimize flexibility and flexibility of the arm. By thus facilitating each disengagement operation, thanks to the use of a force necessary to deform the elastic wheel if possible negligible compared to the characteristics of the materials used, the wear of the gear teeth is minimized and thus the durability of the mechanism proposed is further improved.

According to a particularly preferred embodiment for the power reserve display mechanism according to the invention, the arms are also made of a non-magnetic material.

Thanks to such a choice of material presenting advantageous characteristics in addition to the desired elastic properties, the power reserve display mechanism can be easily integrated as a module of a non-magnetic movement itself intended to present non-magnetic properties. It will be noted that in the context of the invention, the elastic wheel forming the display mobile will preferably be made entirely of a non-magnetic material.

According to a particularly preferential embodiment for the power reserve display mechanism according to the invention, the display mobile is formed in one piece by said hub, said rim provided with partial teeth and said at least an elastic arm connecting said serge to said hub.

Such a one-piece arrangement makes it possible to considerably simplify the mounting and assembly operations of the security mechanism proposed for the display mechanism compared to the solutions of the prior art using elastic coupling elements separated and having to be fixed respectively to each of the parts which they are supposed to mechanically couple.

According to a particularly preferred embodiment, the power reserve display mechanism according to the invention is characterized in that the energy source is formed by a first barrel and a second barrel arranged in series, and that said mobile d The input is formed by a differential engaged on the one hand with a first shaft of the first barrel and on the other hand with a second shaft of the second barrel.

Such an arrangement allows the optimization of the precision and the taking of information from the stored energy by deducing it both from a cocking indication on the first barrel and from a discocking indication on the second barrel, all by doubling the amount of power reserve available thanks to this arrangement of two barrels in series. In this way, we can both maximize the overall power reserve, while improving the precision of the power reserve values that we seek to display to the user of the watch.

According to a particularly preferential embodiment for the power reserve display mechanism according to the invention, the differential comprises a lower board engaged with the first shaft of the first barrel, and a satellite carrier engaged with the second shaft of the second barrel, the lower board and the satellite carrier being coaxial and superimposed.

Such an arrangement for the differential proposed in order to improve the acquisition of power reserve information and to considerably simplify its structure compared to usual differentials using friction wheels; moreover, it provides an additional gain in compactness of the overall display system.

According to an even more preferential embodiment of the power reserve display mechanism according to the invention, the driving element of the input mobile is formed by a differential drive pinion, the pinion drive being coaxial and superimposed on the lower board and the satellite carrier.

Thanks to this particularly advantageous configuration, not only does the differential have a particularly simple structure, the inputs and outputs of which are all coaxial and mutually superimposed, but it can be easily and directly connected to the display mobile provided with the integrated safety mechanism.

According to an even more preferential embodiment of the power reserve display mechanism according to the invention, the lower plate of the differential is integral in rotation with a central wheel engaged with the input wheel of a satellite, the satellite further comprising an output pinion engaging with the drive pinion.

Thanks to this particularly advantageous configuration of the differential, the transmission of information on arming or disarming the barrel is carried out using a mobile comprising a reduced number of parts and in a particularly compact form.

Finally, according to a particularly preferred embodiment for the power reserve display mechanism according to the invention, the display member is a needle moving over a first angular sector corresponding to a first angular range of 240 degrees.

Such an arrangement is particularly advantageous for displaying a potentially high power reserve level, particularly when several barrels are used in series, the angular sector available for display then being chosen accordingly as being deliberately large; the choice of a range greater than 180° degrees but significantly less than 360° aims to provide the most intuitive display possible by always clearly dissociating the highest level from the lowest.

Brief description of the drawings

• la figure 1 est une vue du dessus d'un mécanisme d'affichage de réserve de marche selon un mode de réalisation préférentiel dans le cadre de la présente invention, utilisant deux barillets montés en série et un différentiel ;
• la figure 2 est une vue de profil du mécanisme d'affichage de la figure 1 ;
• la figure 3 est une vue agrandie du mobile d'affichage de la figure 1, mettant en évidence le nombre total de spires, l'épaisseur des bras, et le nombre de spires par bras selon le mode de réalisation préférentiel illustré ;
• La figure 4 est une vue schématique illustrant le détail des secteurs angulaires et plages angulaires utilisés dans le cadre du mode de réalisation préférentiel pour la mise en oeuvre de la présente invention ;
• la figure 5A est une vue du mécanisme d'affichage de réserve de marche de la figure 1 en position désarmée du mouvement ;
• la figure 5B est une vue du mécanisme d'affichage de réserve de marche de la figure 1 en position armée du mouvement

Other advantageous characteristics will emerge more clearly from the following description of a particular embodiment of the invention given by way of non-limiting example and represented by the appended drawings, in which:

• there figure 1 is a top view of a power reserve display mechanism according to a preferred embodiment in the context of the present invention, using two barrels mounted in series and a differential;
• there figure 2 is a profile view of the display mechanism of the figure 1 ;
• there Figure 3 is an enlarged view of the mobile display of the figure 1 , highlighting the total number of turns, the thickness of the arms, and the number of turns per arm according to the preferred embodiment illustrated;
• There Figure 4 is a schematic view illustrating the detail of the angular sectors and angular ranges used in the context of the preferred embodiment for the implementation of the present invention;
• there figure 5A is a view of the power reserve display mechanism of the figure 1 in the disarmed position of the movement;
• there Figure 5B is a view of the power reserve display mechanism of the figure 1 in the armed position of the movement

detailed description

There figure 1 is a top view of the display mechanism for power reserve 1 of a mechanical watch movement according to the invention provided with a safety device for both arming and disarming using only coupling elements elastic. The movement has the particularity of having two barrels mounted in series, that is to say a first barrel 21 and a second barrel 22, whose respective teeth of their drums, that is to say the teeth 211A of the first drum 211 and the teeth 221A of the second drum 221, are in mutual gear engagement. The first barrel 21 is armed by the first shaft 210, the teeth of which 210A mesh with those 51A of an input wheel of a differential mobile 5, formed by a lower board 51 of this differential mobile 5, while the torque accumulated by these two barrels (first barrel 21 and second barrel 22) forming the source of mechanical energy 2 for the movement is transmitted at the output via the second shaft 220 of the second barrel 22, the teeth of which 220A mesh with the main finishing cog . The teeth 220A of the second shaft 220 of the second barrel also mesh, via a gear train formed by a reduction wheel 3 and an intermediate gear 4, with a second input wheel of the differential, formed by a satellite carrier 52 of which we can see the external teeth 52A mesh with those 4A of the intermediate gear 4.

With such a construction, it is thus possible to retrieve in parallel information about the cocking level of the first barrel 21, and the uncocking level of the second barrel 22, and to take an average via the differential mobile 5. Thus, the precision of the information on the quantity of energy stored by the energy source of the movement is improved compared to that of usual solutions using only information relating alternatively to an arming level or a disarming level.

In what follows, we will describe in a little more detail the transmission of the movement via the second shaft 220 of the second barrel and the reduction mobile 3, as well as the differential mobile.

On the figure 1 , the teeth of all the wheels or pinions are represented in solid lines, except those of the reduction pinion 32 (teeth referenced 32A) and the central wheel 55 (whose teeth are referenced 55A), which are represented in dotted lines. In fact, these gear elements are hidden and only visible on the figure 2 aiming to show the different gear planes of all the transmission elements. For the sake of readability, however, we sought to represent these elements also on the figure 1 so that the understanding of how the movement works can be done on the basis of reading this figure alone.

The reduction wheel 3 has a reduction wheel 31 whose teeth 31A mesh directly with the teeth 220A of the second shaft 220 of the second barrel 22. As indicated previously, under this reduction wheel 31 and arranged, coaxially thereto, the reduction pinion 32 which has teeth 32A meshing with the external teeth 4A of an intermediate gear 4 which is also in gear engagement with the second input wheel of the differential formed by the planet carrier 52, and whose teeth external is materialized by the reference 52A. The satellite 53 mounted on the periphery of the planet carrier 52 has a first gear stage formed by the input wheel 531, the teeth of which 531A mesh with those 55A of the central wheel 55, arranged coaxially under the pinion d drive 54 at the output of the differential mobile 5, and an output pinion 532 whose teeth 532A meshes precisely with those 54A of the drive pinion of the differential mobile 5. The satellite 53 is thus not rotated relative to the lower board 51 of the differential mobile, that is to say its first input wheel, only if the winding information of the first barrel 21 supplied to it via the teeth 210A of the first shaft 210 differs from that of the disarming of the second barrel 22 transmitted by the teeth 220A of the second shaft 220 via the cog formed by the reduction mobile 3 and the intermediate return 4 to the second input wheel of the differential 5, that is to say the carrier satellite 52.

Whatever happens, the average of these two pieces of information is transmitted, at the output of the differential mobile, by the drive pinion 54 to the power reserve display mobile 6, the complete structure of which according to this preferred embodiment for the The invention will be described in more detail on the Figure 3 following. For this reason, a rectangle (A) surrounds the display mobile 6 and the content of the elements contained in this rectangle (A), including in particular the integrated security mechanism and the advantageous selective coupling and disengagement properties conferred.

On the figure 1 , we can however visualize the partial teeth 61A of the rim 61 of this display mobile 6, which is provided, in its center, with a hub 60 integral in rotation with a display member produced here in the form of a needle 8, but which could for example take the form of a colored angular sector sliding under a display window. The hand points to a current power reserve value (V) when using the watch. The hub 60 is also connected to the rim 61 via a plurality of elastic arms 62 which allow, at the end of the stroke of the sector corresponding to the partial toothing 61A, a release and therefore an indefinite disengagement at the end of the arming or disarming the energy source of the movement. To complete the complementary non-toothed sector of the serge, a peripheral bead 610 is also provided, the technical functions of which will be specified later.

There figure 2 illustrates a profile view of the transmission gear for the display mechanism according to the invention, that is to say the same elements as those of the figure 1 , simply without the two barrels nor the needle as display member 3. In other words, this figure focuses the transmission to the display mobile 6 via the reduction mobile 3, the intermediate return 4, and the mobile differential 5 to show the compactness obtained, both in terms of thickness and space occupied on the movement plate thanks to at least partial superposition of the display mobile 6 in relation to the other elements.

Each of the elements among the reduction mobile 3, the intermediate return 4, the differential mobile 5, and the display mobile 6 is represented around its respective axis of rotation (O3, O4, O5, O6). The power take-offs in relation to this transmission cog are no longer illustrated in this figure, but we recall that the transmission to the lower board 51 of the differential mobile 5 is carried out by direct gearing to the first shaft 210 of the first barrel 21, while the transmission of the drive torque to the planet carrier 52 of the differential mobile 5 results from the indirect gearing of the latter to the second shaft 220 of the second barrel 22 via the reduction mobile 3 then the intermediate return wheel 4. The mobile of reduction 3 comprises a reduction wheel 31 whose teeth 31A engage with those of the second shaft of the second barrel 220 (not shown in this figure, but referenced 220A on the figure 1 ), as well as a reduction pinion 32 coaxial and integral in rotation with the wheel reduction gear 31, and whose teeth referenced 32A mesh with those, reference 4A, of the intermediate gear 4, and which meshes on the opposite side, with the satellite carrier 52 whose teeth are referenced 52A, which is mounted coaxially, but not integral in rotation just above the lower board 51 of the differential mobile 5. This lower board 51 is mounted coaxial and integral in rotation on the other hand with a central wheel 55, the teeth of which referenced 55A mesh with the teeth referenced 531A of the wheel input of the satellite 53, including the output pinion of the satellite 532, coaxial and integral in rotation with the input wheel of the satellite 531, meshes with the drive pinion 54 of the differential mobile 5. This drive pinion 54 has a teeth referenced 54A in direct engagement with partial teeth 61A for transmission of movement to the display member, not shown in this figure. The drive pinion 54 constitutes the output in terms of kinematic transmission chain relative to the lower board 51 and the satellite carrier 52 constituting a first and a second input wheel for this differential; we can distinguish in this figure the 4 gear planes of the differential mobile 5 constituted by those of its two input wheels (i.e. the lower board 51 and the satellite carrier 52), those of the two coaxial elements and integral in rotation with the satellite 53, that is to say its input wheel 531 and its output pinion 532. The drive pinion 54 is thick enough to finally be able to mesh with the display mobile 6 on a fifth plane gear slightly raised relative to that of the output pinion 532 of the satellite 53, so that the satellite 53 can rotate under it in the event of movement of the satellite carrier 52; a slight height spacing is provided to accommodate manufacturing and assembly tolerances.

Thus, thanks to the power reserve display mechanism 1 proposed in the context of the present invention, it is possible not only to improve the display precision while maximizing the power reserve, but also to minimize the necessary space on the plate and in height on it.

There Figure 3 shows the detail of the display mobile 6 with integrated security mechanism, as indicated previously, by illustrating more precisely the elements contained in the rectangle (A) of the figure 1 .

There Figure 3 thus the display mobile 6 as well as its partial teeth 61A on its rim 61, as well as the hub 60 in its center, the whole being mobile of the axis of rotation referenced O6, that is to say corresponding to that of the display mobile 6 as a whole. The needle integral in rotation with the hub 60 and arranged above the latter constitutes here a display member 8 preferred for the implementation of the invention; this can move for example opposite a scale extending over a predefined angular sector according to the total power reserve of the movement. The hand points to a current power reserve value (V) of the movement, indicating the time remaining before carrying out possible manual winding.

The safety device here consists of a coupling between the hub 60 and the rim 61 of the display mobile 6, that is to say very simply in the plane of the latter, so as to save a maximum of space in height . This coupling is carried out using a plurality of elastic arms 62, wound in a total number of turns N equal here to 6, but which is preferably between 4 and 10 in order to guarantee stability to the serge 61 around of its hub 60, that is to say in the gear plane of the partial teeth 61A with the drive pinion 54 of the differential mobile (not shown in this figure). The total number of turns N corresponds to a number of turns per arm Ns multiplied by the number of arms Nb: $$\mathrm{NOT}=\mathrm{Ns}*\mathrm{No.}$$

The number of turns per arm Ns makes it possible to adjust the flexibility of the clutch, and was chosen in this preferred embodiment as being equal to two to guarantee sufficient flexibility depending on the size chosen. The number of arms Nb contributes more strongly to the rigidity of the display mobile 6 in its gear plane; the number of attachment points in relation to the serge 61 having to be greater than one to avoid any imbalance in terms of inclination, and preferably strictly greater than two in order to guarantee the best possible balance in relation to the hub 60. Thus, according to the illustrated embodiment, the number of arms Nb is equal to 3 while the number of turns per arm Ns is equal to 2, which aims to provide an excellent compromise in terms of flexibility and stability. In order not to return the mobile display 6 too rigid, however, we will preferably choose a number of arms Nb less than or equal to 5.

The last adjustment parameter for coupling the serge 61 to the hub 60 is the thickness E of each elastic arm 62. This is preferably chosen between 5 and 25 hundredths of a millimeter in the proposed configuration, always in the same optics to guarantee the best compromise between flexibility and rigidity; according to the example chosen, it is preferably equal to 15 hundredths of a millimeter. Increasing the thickness E of the arms increases their rigidity, but at the same time prevents arranging a greater total number of turns N for a given size, limited by the interior space of the serge 61.

The proposed configuration makes it possible to guarantee both sufficient rigidity and sufficient flexibility to avoid exerting too many frictional forces on the teeth in mutual gear engagement during disengagement at the end of the cocking and disarming stroke, c that is to say on either side of the angular sector formed by the partial toothing 61A. As can be seen on the Figure 3 , clearances of amplitude D are formed on either side of the ends of the partial teeth 61A of the serge 61, in order to allow optimal interpenetration of the teeth of the gear wheels in mutual engagement, namely that of the serge 61 and that (referenced 54A in the other figures) of the drive pinion 54. The first clearance 611 is located at a first end of the partial toothing 61A of the serge 61, while the second clearance 612 is located at the other end of this partial toothing 61A. As can be seen, the partial teeth 61A and the peripheral bead 610 extend over “complementary” angular sectors, the peripheral bead 610 aiming to virtually replace the missing teeth on the periphery of the serge outside of the two clearances. This peripheral bead 610 thus has a balancing vocation for the display mobile 6 in order to avoid any tendency for it to tilt; it also fulfills the function of an anti-shock device by minimizing the potential movement of the display mobile with respect to the wall of a housing where the latter would be placed, thus avoiding both damage caused to the axes and the impact of the shock.

The one-piece configuration of the display mobile 6 with integrated release mechanism formed by the elastic arms 62 is particularly advantageous in terms of productivity gains, since the power reserve display mechanism 1 proposed has an integrated safety device formed by 'one piece with a display wheel. The materials chosen for the arms preferably have properties of hardness, flexibility and abrasion resistance configured such that each disengagement operation generates almost negligible wear. As an example, we can use Durnico which has interesting properties both in terms of elasticity and friction; however, according to a particularly preferential variant, we will instead use Phynox which also has very good properties in terms of elasticity and ductility for easy production of the elastic arms 62, but which also has the advantage of providing shielding magnetic to the movement, and thus contribute not only to the robustness of the proposed display mechanism with respect to magnetic disturbances, but more generally to the stability of the overall operation of the watch movement.

At the center of the hub is a loop 601, into which a fixed limiting pin 7 is inserted. This limitation pin 7 can move inside the loop 601, until it abuts against a first stop 6011 in one direction, when the movement is in the completely disarmed position (and the power reserve therefore displays “ 0") and against a second stop 6012 in the other direction, when the movement is in the fully armed position. The angular sector over which the loop 601 extends makes it possible to define the amplitude of the display sector in a particularly simple and effective manner, in the plane of the display mobile 6, and without requiring any other dedicated limitation mechanism. In the state where the limitation pin 7 is represented in relation to the loop, the needle can move with a greater amplitude in the direction of clockwise than in the opposite direction, which means, according to the preferred embodiment illustrated, that the current power reserve value (V) corresponds to more than half of the maximum possible level. It will also be noted that the angular range over which the strap extends corresponds substantially to that of the partial teeth 61A of the serge 61; In what follows, we will explain what the slight differences that can be note according to the preferred embodiment described, and what are the technical advantages conferred by such an optimized configuration.

On the Figure 4 , which represents a block diagram of the operation of the display mobile 6 between each extreme, that is to say the maximum and minimum arming level, the emphasis is placed on the comparison of the different display angular ranges and angular sectors for displaying different elements, and in particular the loop 601 of the hub 60, the partial teeth 61A and the peripheral bead 610 of the rim. Inside the loop 601 of the hub 60, the limitation pin 7 is shown in its two extreme display positions, that is to say during complete disarming of the movement where it is in abutment against the first stop 6011 of the loop 601, and during complete arming of the movement where it abuts against the second stop 6012 of the loop 601. The first angular sector S1 over which the loop 601 extends corresponds to a first range angular display P1 of 240°, which has the advantage of being sufficiently large to precisely indicate the variations of a significant power reserve, such as preferably 120 to 130 hours of operation in the context of the invention thanks to the use of two barrels in series, but while allowing the maximum and minimum power reserve values to be intuitively dissociated, which would no longer be the case if the angular range approached too close to 360°. On either side of the partial toothing 61A, at the level of the first clearance 611 and the second clearance 612, the angular movement of amplitude D makes it possible to dissociate the first toothed angular sector S1 from a third non-toothed angular sector S3 corresponding to that over which the peripheral bead 610 of the serge extends. We can clearly see the interest of such an frolic in this figure; this is in fact to allow optimal penetration of the teeth of the gear pinion 54 (the external teeth of which have the reference 54A) into those of the external partial teeth 61A of the serge. It can, however, be noted that this partial toothing 61A extends over a second angular sector S2 which is slightly more restricted than the first angular display sector S1; the second angular range P2 of this second sector preferably being approximately 224°. The technical explanation for this slight difference is due to the fact that we want, at the end of the cocking or disarming stroke, to have only one tooth left, that is to say the last of the partial toothing 61A of the serge, engaging with toothing 54A of the drive pinion 54, so as to generate the minimum possible tension on the elastic arms 62 in order to carry out the disengagement. If the partial toothing 61A extended over exactly the same angular range of 240°, then there would be a mutual gear engagement of at least two more teeth of each of the respective teeth of the gear pinion 54 and the serge 61, so that the disengagement can only be carried out after having carried out a rotational movement of significantly greater amplitude, thus generating much more tension on the elastic arms before the disengagement can take place. Furthermore, the time necessary to carry out the disengagement is reduced (between one hour and two hours for the preferred variant illustrated, compared to 5 to 6 hours in the case where the first angular sector S1 used for the display and the second angular sector S2 on which the partial teeth 61A of the serge 61 is provided are confused.

Consequently, the arrangement of differential angular sectors of amplitude Δ, preferably symmetrically at the edge of the first angular sector S1, makes it possible on the one hand to minimize the tensioning of the elastic arms 62 during unlocking and therefore disengagement operations. ; on the other hand, these differential angular sectors whose sum corresponds to an angular range equal to the difference of the first angular range P1 of the first angular sector S1 and the second angular range P2 of the second angular sector S2 [in other words: 2*Δ = P1 - P2] are intended to minimize the latency time of the display needle during a subsequent re-clutch, in particular after a disengagement at the end of arming, without risk of losing engagement. In the specific case illustrated on the Figure 4 , the amplitude of each differential sector is of the order of 8° which means that the second angular range of the partial toothing is 224°, making it possible to obtain this optimal compromise between minimizing the tension on the elastic arms 62 during disengagement, and at the same time the reduction in latency time during re-clutching.

It will also be possible to note that the differential angular sectors of amplitude Δ are completely included respectively in the first clearance 611 and the second clearance, which thus have an even greater angular swing D, of the order of around twenty degrees. Since the annular peripheral bead 610 is intended to “simulate” teeth almost complete of the serge 61 apart from the clearances aimed at improving the mutual gearing with the drive pinion 54 of the differential, the third angular amplitude P3 of the third angular sector S3 over which the annular peripheral bead 610 of the serge extends is determined by the following formula: $$\mathrm{<figure-callout\; id="3"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}3=360°-\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png"\; state="\{\{state\}\}">P</figure-callout>}2-2*\mathrm{D}.$$

This third angular range P3 thus corresponds, according to the preferred embodiment illustrated, to an angular sector of around a hundred degrees (-100°).

In the preceding embodiment, the amplitude of the movements of each of the clearances D and the differential angular sectors Δ as well as the number of arms Nb and the total number of turns N are configured such that the stresses experienced by the arms elastics 62 are as weak as possible during each disengagement operation. In this way, the risks of breakage and fatigue are limited over time. Furthermore, the materials used in connection with this configuration are chosen such that the forces necessary for tensioning the arms are negligible compared to the characteristics of the materials used; in this way, the durability of the system is improved by minimizing the wear generated on the teeth and pivots.

Finally, the figures 5A And 5B respectively show the display mechanism in its two extreme positions, that is to say when the power reserve is exhausted (case of the completely disarmed movement) and respectively maximum (case of the fully armed movement).

These two figures illustrating elements already introduced in the previous figures, they will not be repeated in detail, in particular with regard to the transmission gear (reduction mobile 3 - intermediate transmission 4 - differential mobile 5). It may be noted that the elements represented in these figures are in all respects identical to those represented in the figure 1 , apart from the drums of each barrel (that is to say the first drum 211 of the first barrel 21 and the second drum 221 of the second barrel 22).

On the figure 5A , the movement is completely disarmed and consequently the limitation pin 7 abuts against the first stop 6011 of the loop 601 of the hub 60; the needle is then in a position where it can only move in the winding direction Sa, which here corresponds to the counterclockwise direction. The power reserve value displayed thus corresponds to the minimum value (Vmin), typically “0”.

Conversely, on the Figure 5B , the movement is fully armed and consequently the limitation pin 7 abuts against the second stop 6012 of the loop 601 of the hub 60; the needle is then in a position where it can only move in the disarming direction Sd, which here corresponds to clockwise direction. The power reserve value displayed thus corresponds to the maximum value (VMax).

The choice of reduction ratios allows the indication of the complete reserve of approximately five days (120 hours), corresponding to the difference in value between the maximum value (Vmax) and the minimum value (Vmin) on a display portion of 240 degrees, which corresponds to the amplitude of the first angular range P1 over which the first angular sector extends over which the loop 601 of the hub extends. The display is therefore extremely precise since one hour of power reserve corresponds to approximately two degrees.

Outside of this 240 degree display range, the safety device provided by the elastic arms 62 connecting the central hub 60 to the rim 61 of a partially toothed display wheel 6 driven by the drive pinion 54 at the output of the differential mobile makes it possible to avoid any breakage of one or more components, despite the fact that the limiting pin 7 then blocks any additional movement of the indication system.

In the above, apart from the fact that we have introduced a new solution provided with a more reliable security system not using elastic coupling means between the indicator part and the driving part of the reserve mechanism of working, we have described a preferred embodiment for the implementation of the present invention, which uses two barrels in series as a source of energy. The type of barrel, that is to say fixed flange or sliding flange, has not been specified. Those skilled in the art will, however, understand that the invention can be carried out with any type of barrel and independently of their number as a source of mechanical energy, the heart of the invention consisting of decoupling the display member of the power reserve, such as a hand, potentially to infinity both during winding, and at the end of the stroke when the movement continues its movement beyond the minimum level of the range planned display.

The invention also allows the production of a differential of simplified construction compared to those relatively complex using a friction wheel for disengagement, which allows easier manufacturing and assembly thanks to the elimination of the time spent searching for the optimal friction torque via specific sizing and lubrication, as well as the control of each series of components produced. In this way, we also eliminate any risk of friction that is too strong which would cause too much wear on the parts or too low which would cause a problem with the transmission by not engaging the clutch when it should. This improves precision and durability.

The elimination of lubrication is an additional argument in favor of durability, because there is no longer any wear linked to the aging of the oils, and after-sales service will also be easier.

Claims (14)

Power reserve display mechanism (1) of a timepiece powered by a mechanical energy source (2), comprising an input mobile provided with a drive element driven in a first direction during of arming and in a second direction opposite to said first direction when disarming said energy source (2), said drive element being arranged to receive an information value (V) relating to said current power reserve , and transmit it to a rotating display member (8) capable of moving on a first angular sector (S1) corresponding to a first angular range (P1) predefined between a minimum value (Vmin) and a maximum value ( Vmax) display, said power reserve display mechanism (1) being characterized in that said mobile display member (8) is integral in rotation with the hub (60) of a display mobile (6 ), which display mobile (6) further comprising a rim (61) provided with partial teeth (61A) extending only over part of its periphery and which is arranged to mesh with said drive element, said serge (61) and said hub (60) being connected to each other via at least one elastic arm (62). Power reserve display mechanism (1) according to claim 1, said hub (60) being further provided with a loop (601) extending over a first angular sector (S1) corresponding to said first angular range ( P1) predefined, and a fixed limitation pin (7) being housed in said loop (601) and being able to abut on either side of it for the respective display of said minimum value (Vmin) of display and said maximum display value (Vmax). Power reserve display mechanism (1) according to claim 2, the partial teeth (61A) of the rim extending over a second angular sector (S2) strictly included in said first angular sector (S1). Power reserve display mechanism (1) according to one of the preceding claims, wherein said partial toothing (61A) of said rim (61) is formed by external peripheral toothing of said display wheel (6). Power reserve display mechanism (1) according to one of claims 3 or 4, said rim (61) being furthermore provided with an external peripheral bead (610) extending over a third angular sector (S3) corresponding to a third angular range (P3), said third angular sector (S3) being located strictly outside said second angular sector (S2). Power reserve display mechanism (1) according to one of the preceding claims, comprising a number of arms (Nb) of between 2 and 5. Power reserve display mechanism (1) according to one of the preceding claims, comprising a total number of turns (N) of between 4 and 10. Power reserve display mechanism (1) according to one of the preceding claims, characterized in that said elastic arms (62) are also made of a non-magnetic material. Power reserve display mechanism (1) according to one of the preceding claims, characterized in that the display mobile (6) is formed in one piece by said hub (60), said rim (61) provided of partial teeth (61A) and said at least one elastic arm (62) connecting said serge (61) to said hub (60). Power reserve display mechanism (1) according to one of the preceding claims, characterized in that said energy source (2) is formed by a first barrel (21) and a second barrel (22) arranged in series , and that said input mobile is formed by a differential (5) engaged on the one hand with a first shaft (210) of said first barrel (21) and on the other hand with a second shaft (220) of said second barrel (22). Power reserve display mechanism (1) according to claim 9, wherein the differential (5) comprises a lower board (51) engaged with said first shaft (210) of said first barrel (21), and a carrier satellite (52) engaged with said second shaft (220) of said second barrel (22), said lower board (51) and said satellite carrier (52) being coaxial and superimposed. Power reserve display mechanism (1) according to claim 9 or 10, in which said driving element of said input wheel is formed by a drive pinion (54) of said differential (5), said pinion d the drive being coaxial and superimposed on said lower board (51) and said satellite carrier (52). Power reserve display mechanism (1) according to claim 11, in which said lower plate (51) of the differential is integral in rotation with a central wheel (55) engaged with the input wheel (531) of a satellite (53), said satellite further comprising an output pinion (532) engaged with said drive pinion (54). Power reserve display mechanism (1) according to one of the preceding claims, in which said display member (8) is a needle moving on a first angular sector (S1) corresponding to a first angular range (P1 ) of 240 degrees.

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