EP3112949B1 - Mechanical power source for a clock movement - Google Patents

Description

Technical area

• un organe d'entrée destiné à être agencé en prise avec un mécanisme de remontage du mouvement horloger pour permettre de charger le ressort,
• un organe de sortie destiné à être agencé en prise avec un mobile du mouvement horloger pour permettre au ressort de libérer son énergie dans le mouvement horloger, sous la forme d'un couple de sortie.

The present invention relates to a mechanical energy source, for a watch movement, comprising
a barrel comprising a shaft and a drum, coaxial and free to rotate relative to each other, the drum housing a spring arranged spirally around the shaft and having a first connecting portion connected to the shaft and a second connecting portion connected to the drum, the barrel comprising

• an input member intended to be arranged in engagement with a winding mechanism of the watch movement to enable the spring to be loaded,
• an output member intended to be arranged in engagement with a mobile watch movement to allow the spring to release its energy in the watch movement, in the form of an output torque.

State of the art

Sources of mechanical energy of this type are well known in the field of watchmaking.

A recognized problem which is associated with the use of a mainspring is that the output torque that it delivers to the watch movement generally depends on its state of charge. However, the chronometric performance of a watch movement depends largely on the torque delivered by the barrel.

Thus, many developments have already been made to try to minimize the impact of the variation of the torque delivered by the barrel on the operation of the time base of the watch movement, or to make this torque as constant as possible.

The first approach has allowed the development of watchmaking movements of the constant force type or winding equal. However, these watch movements are difficult to develop and therefore expensive, which limits the use in parts of very high quality. range. In addition, the corresponding mechanisms are often delicate and their reliability can quickly be undermined especially in case of shock.

Also, the Applicant has carried out research to develop a solution rather of the second approach mentioned above.

This second approach has already led to different types of solutions in the past.

On the one hand, constructions are known in which work has been carried out on the barrel and its spring to try to reduce as much as possible the torque variations at the outlet of the barrel. For example, the patent application CH704576A2 discloses a particular mode of folding of a barrel spring to limit the variations in the torque delivered by the corresponding barrel depending on the state of charge of the spring. Other known solutions (and mentioned in the aforementioned document) relate to the manufacture of a cylinder spring whose cross section is variable to take into account the modification of its mechanical properties as a function of its state of charge.

The present invention however relates to an alternative solution to that which has just been described. Indeed, the mechanical power source according to the invention advantageously comprises an output torque control mechanism arranged to limit the variations in a predefined range of use in terms of state of charge of the mainspring.

Constructions having such characteristics have also already been developed, to reduce the variations in the torque delivered to the watch movement by the barrel, by coupling a compensation mechanism of the torque delivered directly to the outlet of the barrel. By way of example, each of the patent applications WO2012 / 168443A2 and EP1914604A1 discloses a compensation mechanism arranged at the barrel outlet and making it possible to compensate for variations in the torque exiting the barrel in order to deliver a substantially constant torque to the watch movement.

Licences CH287276 and US167,372 disclose other barrel constructions intended to limit the variations of the delivered torque, by direct action on the mainspring.

The teaching of the patent application will also be noted EP2515185A1 which assumes that the traditional barrel can not achieve the desired constant torque. Thus, this document discloses the construction of a source of mechanical energy comprising a shaft and a coaxial ring and free to rotate relative to each other, a spring made in the form of an elastically deformable beam being housed inside the crown. This construction comprises an input member arranged in engagement with a winding mechanism of the spring and an output member arranged in engagement with a mobile of a watch movement to allow the spring to release its energy in the watch movement in the form of a substantially constant output torque. One of these bodies cooperates with the tree and the other with the crown. To regulate the value of the delivered torque, the construction also comprises an output torque control mechanism arranged to act on the spring and to vary the active length as a function of its state of charge.

Disclosure of the invention

A main object of the present invention is to propose an alternative construction of a mechanical energy source of the type which has just been described, comprising a regulation mechanism making it possible to reduce as much as possible the variations in the torque coming directly out of the barrel when the state of charge of the mainspring varies between its minimum and maximum values. By acting directly on the cylinder itself, there is no need to add a compensation mechanism at the exit of the barrel. Preferably, this object is accomplished by limiting the impact in terms of overall bulk of the energy source, in particular by limiting the number of additional components required outside the barrel.

To this end, the present invention relates more particularly to a mechanical energy source, for a watch movement, of the type mentioned above, characterized in that the mechanical energy source comprises a regulation mechanism including a control member arranged to cooperate with the spring and define a variable active length in a function of the state of charge of the mainspring in order to limit the variation of the output torque with reference to the variation of torque observed with an equivalent barrel of conventional construction.

Thanks to these characteristics, the value of the active length of the mainspring is permanently defined as a function of the state of charge of the spring, to regulate the value of the torque delivered to the watch movement, so that in the best in some cases, this value remains substantially constant regardless of the state of charge of the mainspring.

According to a preferred embodiment, the control mechanism comprises a support carrying the control member and having a first kinematic connection with the drum and a second kinematic connection with the shaft, so that its position with reference to the portions of Spring connection varies depending on the state of charge of the spring.

The support is preferably arranged to be mobile in rotation, with reference to the barrel, being coaxial with the shaft and the drum. In this case, the support can advantageously be pivoted at least indirectly on the shaft.

According to a preferred embodiment, the control member is arranged on the support such that it is likely to move in a substantially radial direction with reference to the support. In addition, the control member advantageously comprises a finger arranged between two turns of the spring to exert a substantially radial pressure on one of the two turns, under the effect of the action of an elastic member and so as to define a contact region, to lock the coil against the drum by compression, and neutralize a portion of the spring substantially between the second connecting portion and the contact region.

With regard to the drive of the support, it can be provided that the regulation mechanism comprises at least one satellite mounted pivoting on the drum and comprising a first wheel, arranged in engagement with a sun gear integral with the shaft, and a second wheel, arranged in engagement with a toothed wheel secured to the support, the first and second wheels being secured in rotation.

The support can then advantageously have the shape of a disc arranged free to pivot on the shaft and so as to be guided by a guide surface of the drum.

The present invention also relates to a watch movement comprising a source of mechanical energy having the characteristics which have just been exhibited, as well as a timepiece equipped with such a watch movement.

Brief description of the drawings

• la figure 1 représente une vue de dessus en perspective simplifiée illustrant des détails de construction d'une source d'énergie mécanique pour mouvement horloger selon un mode de réalisation préféré de l'invention;
• la figure 2 représente une vue de dessus en perspective simplifiée, similaire à la vue de la figure 1, sur laquelle des détails de construction supplémentaires sont illustrés;
• la figure 3 représente une vue en perspective et en coupe simplifiée de la source d'énergie mécanique selon le mode de réalisation préféré partiellement illustré sur la figure 1, dans un premier état de fonctionnement, et
• la figure 4 représente une vue en perspective et en coupe simplifiée similaire à la vue de la figure 3, dans un deuxième état de fonctionnement.

Other features and advantages of the present invention will appear more clearly on reading the detailed description of a preferred embodiment which follows, made with reference to the accompanying drawings given by way of non-limiting examples and in which:

• the figure 1 represents a simplified perspective top view illustrating construction details of a mechanical energy source for watch movement according to a preferred embodiment of the invention;
• the figure 2 represents a top view in simplified perspective, similar to the view of the figure 1 , on which additional construction details are illustrated;
• the figure 3 is a perspective view in simplified section of the mechanical power source according to the preferred embodiment partially illustrated on the figure 1 in a first operating state, and
• the figure 4 represents a perspective view in simplified section similar to the view of the figure 3 in a second operating state.

Mode (s) of realization of the invention

The figures 1 and 2 represent the same simplified perspective top view of a portion of a mechanical energy source according to a preferred embodiment of the present invention.

The mechanical power source comprises a barrel 1 having frame elements of conventional type, that is to say a drum 2 pivoted on a shaft 4, these two members being coaxial. The shaft 4 is here intended to be pivoted between two frame members of the watch movement (not shown) in the usual manner, without limitation.

The barrel 1 contains a barrel spring 6, arranged generally around the shaft by forming a spiral curve, and is closed by a cover 8 ( Figures 3 and 4 ).

A bung 10 is also engaged on the shaft 4 to allow the assembly of a first connecting portion of the spring 6 to the shaft, typically its inner end. Conventionally, it is also planned to assemble a second connecting portion of the spring 6 to the drum 2, generally its outer end.

By way of non-limiting illustration, the shaft 4 here fulfills the function of input member of the barrel, being intended to be rotated by a winding train, in a conventional manner, to recharge the mainspring spring 6. The drum 2 serves as an output member, to allow the barrel spring to release its mechanical energy in the watch movement through it, and is intended to mesh with a mobile movement. Of course, the skilled person can adapt the present teaching according to his own needs without departing from the scope of the invention, in particular by inverting the input and output functions as they are assigned here to the tree and the drum.

The mechanical energy source according to the present invention further comprises a mechanism for regulating the torque delivered by the barrel to the watch movement.

In general, the torque of a spiral spring in bending depends on its modulus of elasticity (E), its quadratic moment (e ³ , h), its length (L) and its arming angle (θ ), that is to say the angle separating its two ends from one another (the two connecting portions of the spring here), and responds to the following relationship: $$\mathrm{VS}\left(\mathrm{\theta }\right)=\frac{\mathrm{E}\cdot e^3\cdot \mathrm{<figure-callout\; id="12"\; label="h"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">h</figure-callout>}}{12\cdot \mathrm{The}}\cdot \mathrm{\theta }$$

The Applicant has sought a solution to take into account the variation of the arming angle over time and regulate the value of the torque delivered accordingly, so that the latter remains as constant as possible, in any case such in a way that it presents a limited variation with reference to the variation observed with an equivalent barrel of conventional construction.

dans laquelle le rapport $\frac{\mathrm{\theta }}{\mathrm{L}\left(\mathrm{\theta }\right)}$

est sensiblement constant.For this purpose, the Applicant has developed a construction comprising a regulation mechanism varying the active length of the mainspring 6 as a function of its state of charge, in other words, such that L becomes dependent on θ to maintain generally constant value of C presented above. This gives the following new relation, valid for the energy source according to the present invention: $$\mathrm{VS}\left(\mathrm{\theta }\right)=\frac{\mathrm{E}\cdot e^3\cdot \mathrm{<figure-callout\; id="12"\; label="h"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">h</figure-callout>}}{12}\cdot \frac{\mathrm{\theta }}{\mathrm{The}\left(\mathrm{\theta }\right)}$$

in which the report $\frac{\mathrm{\theta }}{\mathrm{The}\left(\mathrm{\theta }\right)}$

is substantially constant.

According to the illustrated embodiment, the regulation mechanism comprises components for measuring the state of charge of the mainspring spring 6, visible on the figure 1 .

More specifically, the regulation mechanism comprises a sun gear 12 which is rotatably connected to the shaft 4. It is advantageous to provide the sun gear 12 with frictional engagement on the shaft 4 so that it is not driven. by the shaft when the winding is actuated while the spring is already in its state of maximum load. Alternatively, a clutch can also be considered elsewhere in the winding train.

It will be noted that if barrels commonly referred to as "a tower" are known, the typical barrels currently used are made with an amplitude of armor extending over several turns (usually eight turns). In any case, the implementation of the present invention is not limited by this amplitude of arming. The skilled person can adapt the present teaching without particular difficulty according to his own needs without departing from the scope of the invention.

In addition, the regulation mechanism comprises two satellites 14 mounted free to rotate on the drum 2 and each of which comprises first and second wheels 16, 18 integral in rotation (the first wheels 16 being visible on the sections of the wheels). Figures 3 and 4 ). The first wheel 16 of each satellite 14 is arranged in engagement with the sun gear 12, while the second wheel 18 of each satellite 14 is arranged in engagement with the internal toothing of a ring-shaped peripheral wheel 20.

Thus, the peripheral wheel 20 is rotated in a first direction when the barrel spring is loaded and in the opposite direction when the barrel spring is discharged, which makes it able to constitute an indicator of the state of charge of the barrel. spring.

The reduction gear ratio of this gear train makes it possible to control the speed of rotation of the peripheral wheel with respect to the sun gear (and therefore the speed of rotation of the wheel relative to the speed of the load / discharge of the spring).

The peripheral wheel 20 has a plurality of notches 22 at its outer periphery for angular indexing of a support 24, illustrated in FIGS. figures 2 , 3 and 4 , of which positioning members 26 of shape complementary to the notches ensure that the wheel 20 and the support 24 are integral in rotation.

The support 24 has the general shape of a disk in which a recess 30 is formed, in the direction of its thickness, on an area here representing a little less than a quarter of its total area, by way of nonlimiting illustration.

The support 24 carries a control member 32 of the active length of the mainspring spring 6, arranged in the recess 30.

The member 32 comprises an elongate base 34 carrying a guide lug 36 at a first end and a finger 38, substantially parallel to the barrel shaft 4 and whose function will be explained later, near its second end.

Furthermore, an elastic return member 40 is also arranged in the recess 30 to exert a pressure force on the control member 32, tending to push it here in the direction of the wall of the drum 2.

A generally disk-shaped plate 42 covers the support 24 to define a guide path for the control member 32. For this purpose, the support 24 also has an elongate opening 44 extending in a substantially radial direction, the width is less than that of the guide lug 36. It is then understood that the control member 32 is enclosed between the support 24 and the plate 42 so that it can have a substantially radial translation movement. The plate 42 is made integral with the support 24 in any suitable manner, here preferably by placing screws in holes 46.

The Figures 3 and 4 partially represent the source of mechanical energy which has just been described in similar views, in perspective and in section, the mainspring spring 6 being visible.

The figure 3 illustrates the source of mechanical energy while the mainspring spring 6 is in or near its maximum state of charge, while the figure 4 illustrates it while the mainspring spring 6 is close to its minimum state of charge.

The finger 38 is made of a material such that it can slide along the barrel spring 6 with little friction. It may be of any suitable material, for example of steel coated with ADLC, without departing from the scope of the present invention. In another embodiment, this function can be performed by a roller pivoting on an axis.

The finger 38 is inserted between two adjacent turns of the mainspring spring 6 to exert a substantially radial pressure on the turn located outside, under the effect of the action of the elastic return member 40. The finger 38 defines and a contact region on the spring 6, by pressure on which it locks the outer turn against the drum 2, by compression, and neutralizes the portion of the spring substantially between the outer end of the spring and the contact region concerned.

The locking of the turn is made directly against the wall of the drum 2 when it is the last turn on which the finger 38 rests. This is in particular the case illustrated in FIG. figure 3 when the load of the mainspring is in or near its maximum value.

Otherwise, the support 24 is rotated in a manner defined by the two kinematic chains which connect it, via the satellites 14, on the one hand, to the barrel shaft and, on the other hand, to the drum. As mentioned above, the regulation mechanism comprises a differential gear having an output controlled from the movements of the shaft and the drum and arranged to drive the support 24. Also, the latter is rotated by a such that its angular position is representative of the state of charge of the mainspring spring 6.

When the spring is discharged, the finger 38 follows a spiral curve and passes progressively from one turn to the next in the direction of the barrel shaft 4.

Finally, when the spring is almost completely discharged, as shown in figure 4 , almost all the turns are glued to each other by being compressed against the wall of the drum 2 by the finger 38.

In this case, the active length of the spring is minimal or almost, which makes it possible to deliver a torque at the barrel output of a value substantially equal to the value of the torque when the spring is fully loaded, in which situation the active length is maximum.

Thus, a regulation mechanism is obtained by which the torque delivered to the watch movement has a limited variation with reference to the torque variation observed with an equivalent barrel of conventional construction, or is substantially constant over the entire range of use of the mainspring , in terms of load, in the best case.

It will be noted that the construction according to the preferred embodiment which has just been described makes it possible to obtain an improved source of mechanical energy, while limiting as much as possible the impact in terms of overall bulk of the energy source. .

It will also be noted that a modification of the reduction ratio k of the epicyclic gear train arranged inside the barrel makes it possible, in practice, to slightly modify the shape of the discharge curve of the barrel, and therefore the effective variation of the torque on the range of use of the mainspring.

Furthermore, it can advantageously be provided that the support 24 rests at least indirectly on a guide surface 50 of the drum 2 to improve its stability, as is apparent from the Figures 3 and 4 .

According to one variant, the regulation mechanism which has just been described may comprise several bearing fingers 38 for distributing the load on the spring 6. In this case, the elastic return member 40 may have for example the shape of a hairspring to act on all fingers 38.

In general, the source of mechanical energy as just described can be combined with complementary solutions already known without departing from the scope of the invention, such as for example the realization of a mainspring barrel section variable or with a particular folding mode, as mentioned in the part relating to the prior art.

The foregoing description attempts to describe a particular embodiment by way of non-limiting illustration and the invention is not limited to the implementation of certain particular features which have just been described, for example the forms or the mode of implementation of the components of the regulation mechanism in the barrel as illustrated and described, or even the mode of connection of the spring to the drum and to the shaft. Part of the components may also be arranged outside the barrel without departing from the scope of the invention.

Indeed, it can be provided as an alternative to what has been described that the support 24 carrying the finger 38 is fixed with reference to the drum but that the finger itself is rotated, in a manner that depends on the state load of the spring, to act on a turn and, for example, extract a longer or shorter portion of the spring out of the drum, to neutralize it, and thus change the active length. In this case, the finger would advantageously be made of a material chosen in such a way that significant friction would occur between the finger and the spring, for example rubber. It is then understood that the second connecting portion of the (external) drum spring would not be unique but rather that it would move along the spring as a function of the state of charge of the latter.

It is also possible, as an alternative to the embodiment described, for the finger 38 to undergo a pressure force exerted by the elastic member oriented towards the barrel shaft 4, to neutralize the portion of the spring situated between its internal end. and the corresponding contact region.

The person skilled in the art will not encounter any particular difficulty in adapting the content of the present disclosure to his own needs and A mechanical power source for a watch movement comprising a control mechanism arranged to control the active length of the mainspring depending on its state of charge, without departing from the scope of the invention.

Claims (11)

1. A mechanical energy source for a clockwork movement, including a barrel (1) comprising an arbor (4) and a drum (2), which are coaxial and free to rotate relative to one another, said drum (2) housing a spring (6) arranged in a spiral around said arbor (4) and having a first connecting portion connected to said arbor (4) and a second connecting portion connected to said drum (2), said barrel (1) comprising

   - an input member intended to be arranged engaged with a winding mechanism of the clockwork movement to make it possible to load said spring (6),

   - an output member intended to be arranged engaged with a wheel of the clockwork movement to allow said spring (6) to release its energy into the clockwork movement, in the form of an output torque,

   the mechanical energy source further including a regulating mechanism including a control organ (32) arranged to cooperate with said spring (6) and to define an active length thereof that is variable as a function of the load state of the barrel spring in order to limit the variation of the output torque.
2. The mechanical energy source according to claim 1, including a support (24) carrying said control organ (32) and having a first kinematic connection with said drum (2) and a second kinematic connection with said arbor (4), such that its position in reference to said first and second connecting portions of said spring (6) varies as a function of the load state of said spring (6).
3. The energy source according to claim 2, characterized in that said support (24) is arranged to be rotatable, in reference to said barrel (1), while being coaxial to said arbor (4) and said drum (2).
4. The energy source according to claim 2 or 3, characterized in that said support (24) is pivoted at least indirectly on said arbor (4).
5. The energy source according to one of claims 2 to 4, characterized in that

   said control organ (32) is arranged on said support (24) such that it is able to move in a direction substantially radial in reference to said support (24), and

   in that said control organ (32) includes at least one finger (38) arranged between two turns of said spring (6) to exert a substantially radial pressure on one of said two turns, under the effect of the action of an elastic organ (40) and so as to define at least one contact region, to lock said turn against said drum (2), by compression, and to neutralize a portion of said spring (6) substantially comprised between said second connecting portion and said contact region.
6. The energy source according to one of claims 2 to 5, characterized in that said regulating mechanism includes a differential gear (12, 14, 16, 18, 20) having an output (20) commanded from movements of said arbor (4) and said drum (2) and arranged to ensure the driving of said support (24).
7. The energy source according to claim 6, characterized in that said regulating mechanism includes at least one planetary wheel (14) mounted pivoting on said drum (2) and comprising a first wheel (16) arranged engaged with a solar wheel (12) secured to said arbor (4) as well as a second wheel (18) arranged engaged with a gear wheel (20) secured in rotation with said support (24), said first and second wheels (16, 18) being secured to one another in rotation.
8. The mechanical energy source according to claim 7, characterized in that said support (24) is in the form of a disc arranged free to pivot on said arbor (4) and so as to be guided by a guide surface (50) of said drum (2).
9. The mechanical energy source according to claims 7 and 8, characterized in that said gear wheel (20) secured to said support (24) has inner teeth arranged engaged with said second wheel (18).
10. A clockwork movement (1) including a mechanical energy source according to one of claims 1 to 9.
11. A timepiece including a clockwork movement according to claim 10.

Images