CH719127A2 - Clockwork mechanism comprising a pivoting member. - Google Patents

Abstract

The present invention relates to a watch mechanism (1) comprising a pivoting member (11) mounted on a pivoting axis (10) and subjected to the action of at least one spring (100) arranged to work in a predetermined range of winding angles, said spring (100) comprising at least one elastic arm (102) having, at a first end, a first rotary element (104) secured at least in rotation to the pivot axis (10) of the pivoting member (11) and, at a second end, a second element (106) mounted on a support and arranged to be rotatable or fixed relative to said support during normal operation of the pivoting member. The second element (106) is arranged to be movable relative to said support prior to the normal operation of the pivoting member (11) and the watch mechanism (1) comprises a device (20) for moving the second element (106) by relative to its support arranged to, prior to the normal operation of the pivoting member (11), move the second end of the elastic arm (102) from a first position, in which said spring (100) applies a torque C1 in at least a portion of the predetermined range, at a second position, wherein the elastic arm (102) exhibits a compression or elongation different from that of the first position such that said spring (100) applies a torque C2 different from C1 in at least least part of the predetermined range

Description

Technical area

The present invention relates to a watch mechanism comprising a pivoting member mounted on a pivot axis and subjected to the action of at least one spring arranged to work within a predetermined range of winding angles, said spring comprising at at least one elastic arm having, at a first end, a first rotary element integral at least in rotation with the pivot axis of the pivoting member and, at a second end, a second element mounted on a support and arranged to be rotatable or fixed relative to said support during normal operation of the pivoting member.

The present invention also relates to a timepiece comprising such a mechanism.

State of the art

[0003] Such a pivoting member is for example a finger acting on a rocker having a feeler cooperating with a snail cam of an instantaneous minute counter mechanism of a chronograph, as described in publication WO 2020/016818 or in the applicant's application EP20173411. The first rotatable element of the spring is mounted on the pivot axis of the finger so that the first end of the spring is pivoted. The rocker is held against the periphery of the snail cam by said spring acting on the pivot axis of the finger, this finger itself acting on the rocker. With each revolution of the cam, the rocker rises along the cam, which progressively arms the spring. The pivoting member can also be the rocker itself, the first rotating element of the spring 20 then being mounted on the axis of the rocker.

[0004] In publication WO 2020/016818, the spring has, at its second end, a base fixed to the frame of the watch mechanism by two pins, so that the first end of the spring is pivoted and the second end of the spring is embedded .

[0005] In application EP20173411, the spring has at its second end a second rotary element also pivotally mounted on the frame so that the first and second ends of the spring are pivoted.

[0006] The pivoting member described in application EP20173411 can also be subjected to the action of a plurality of springs arranged to generate a pivoting torque on the pivoting member, the pivoting member comprising a hub integral with the pivot pin and a serge. Such a pivoting member can be used as a power source or regulating member.

[0007] The assemblies with pivoted/recessed or pivoted/pivoted ends described respectively in publication WO 2020/016818 and in application EP20173411 make it possible, in preferred configurations, to obtain a spring having substantially zero stiffness and therefore a constant torque in the predetermined range of angular positions that the first rotating element can assume during operation of the mechanism. This makes it possible, for example, to reduce the intensity of the force applied to the snail cam by the spring compared to a traditional spring, thus reducing the energy required to rotate the snail cam.

[0008] However, with the possible dispersions in the manufacture of the springs, it is possible that the torque actually obtained is different from the desired torque. If the torque obtained is higher, it is still possible to go through a height bet. If the torque obtained is lower, it is then necessary to dismantle the mechanism in order to rework the springs.

The present invention aims to remedy these drawbacks by proposing a watch mechanism allowing in situ adjustment of the stiffness of the spring(s) of the pivoting member, the mechanism being already mounted in the movement, in order to obtain the desired torque without having to dismantle the mechanism.

Disclosure of Invention

To this end, the invention relates to a watch mechanism comprising a pivoting member mounted on a pivot axis and subjected to the action of at least one spring arranged to work in a predetermined range of winding angles, said spring comprising at least one elastic arm having, at a first end, a first rotating element integral at least in rotation with the pivot axis of the pivoting member and, at a second end, a second element mounted on a support and arranged to be rotatable or fixed relative to said support during normal operation of the pivoting member.

According to the invention, the second element is arranged to be movable relative to said support prior to normal operation of the pivoting member and the watch mechanism comprises a device for moving the second element relative to its support arranged to, prior to the normal operation of the pivoting member, moving the second end of the elastic arm from a first position in which said spring applies to the pivoting member a torque C1 in at least part of the predetermined range to a second position in which the elastic arm has a compression or an elongation different from that of the first position so that said spring applies to the pivoting member a torque C2 different from C1 in at least part of the predetermined range.

[0012] Thus, the moving device makes it possible to move one end of the elastic arm so as to cause additional compression making it possible to produce a negative stiffness or so as to cause additional elongation of the elastic arm making it possible to produce a positive stiffness, so to be able to adjust the stiffness of the spring in situ, and therefore the torque applied by the spring to the pivoting member, directly in the mechanism.

Thus, the watch mechanism according to the invention, allowing in situ adjustment of the torque applied by the spring to the pivoting member, has great flexibility.

The present invention also relates to a timepiece comprising a timepiece mechanism as defined above.

Brief description of the drawings

Other characteristics and advantages of the present invention will appear on reading the following detailed description of various embodiments of the invention, given by way of non-limiting examples, and made with reference to the accompanying drawings in which : FIG. 1 is a plan view from above of a spring used in the timepiece mechanism according to the invention, in the variant with two pivoted ends, the spring appearing in light being in the rest position and the spring appearing in dark having its elements rotary pivoted to occupy an angular position θ relative to the rest position; FIG. 2 is a plan view from above of a timepiece mechanism comprising a pivoting member according to an exemplary embodiment of the invention; FIG. 3 is an isometric view of a device for moving the second element used in the present invention when the second end of the spring is pivoted, in the form of an eccentric; Figure 4 is a top view of a pivoting member according to another embodiment of the invention; FIG. 5 is a graphic representation of the normalized moment exerted in a spring with pivoted and recessed ends as a function of the angular displacement of the first rotary element, the second recessed end of the spring being in its first position (curve C1), the second recessed end of the spring having been moved into its second position by causing compression (curve C2) and the second embedded end of the spring having been moved to its second position by causing elongation (curve C3); FIG. 6 is a graphical representation of the normalized stress on a spring with pivoted and recessed ends as a function of the angular displacement of the first rotary element, the second recessed end of the spring being in its first position (curve Ct1), the second recessed end of the spring having been moved into its second position by causing compression (curve Ct2) and the second embedded end of the spring having been moved to its second position by causing elongation (curve Ct3); FIG. 7 is a graphic representation of the normalized moment exerted in a spring with two pivoted ends as a function of the angular displacement of the first rotary element, the second pivoted end of the spring being in its first position (curve C1'), the second pivoted end of the spring having been moved into its second position by causing compression (curve C2') and the pivoted second end of the spring having been moved into its second position by causing elongation (curve C3'); FIG. 8 is a graphical representation of the normalized stress on a spring with two pivoted ends as a function of the angular displacement of the first rotating element, the second pivoted end of the spring being in its first position (curve Ct1'), the second pivoted end of the spring having been moved into its second position by causing compression (curve Ct2') and the pivoted second end of the spring having been moved into its second position by causing elongation (curve Ct3'); And FIG. 9 is an isometric view of a spring and of a device for moving the second element used in the present invention when the second end of the spring is recessed.

Embodiments of the Invention

In the context of the present invention, the term "stiffness" means the tangential stiffness.

Referring to Figures 1, 2 and 4, the present invention relates to a watch mechanism comprising a pivoting member 11, 110 mounted on a pivot axis and subjected to the action of at least one spring 100 arranged to work in a predetermined range of lay angles.

As shown in Figure 1, the spring 100 comprises at least one elastic arm 102 in the form of a blade having at its first end 102a a first rotary member 104 integral at least in rotation with the pivot axis of the pivoting member 11, 110. Said pivot axis of the pivoting member is mounted pivoted for example on an element of the frame 1a of the watch mechanism. The first rotary element 104 has for example the shape of a triangular ring as in Figure 1 or circular as in Figures 2 and 3. It is made integral in rotation with the pivot axis of the pivoting member 11, 110 for example by driving on said axis or any other appropriate fixing means. The first rotating element 104 can also form a single piece with its pivoting member.

The elastic arm 102 has at its second end 102b a second element 106 mounted on a support and arranged to be rotatable relative to said support during normal operation of the pivoting member 11, 110, the two ends 102a, 102b of the spring 100 then being advantageously pivoted during normal operation of the pivoting member 11, 110, or to be fixed relative to said support during normal operation of the pivoting member 11, 110, the first end 102a of the spring 100 being pivoted and the second end 102b of the spring 100 then being embedded during normal operation of the pivoting member.

The second element 106 may for example have a triangular shape as shown in Figure 1 or globally the shape of a circular ring as shown in Figures 2 and 4. The mounting of the second element 106 on its support will be described later .

According to the embodiments chosen, the support may be constituted by the frame 1a of the watch mechanism, as shown in Figure 2, or by a movable element 114 of the pivoting member 110 arranged to be movable relatively with respect to the pivot axis of said pivoting member 110, as shown in Figure 4.

In one embodiment, the second element 106 of the spring 100 can therefore be fixed relative to the frame 1a of the timepiece mechanism during normal operation of the pivoting member 11, the first element 104 of the spring 100 being rotatable.

In another embodiment, the second element 106 of the spring 100 can be fixed relative to a movable element 114 of the pivoting member 110 arranged to be movable relatively relative to the pivot axis of said pivoting member when normal operation of the pivoting member, the first element 104 of the spring 100 being rotatable.

In another embodiment, the second element 106 of the spring 100 can be rotatable relative to the frame 1a of the timepiece mechanism during normal operation of the pivoting member 11, the first element 104 of the spring 100 also being rotatable.

In another embodiment, the second element 106 of the spring 100 can be rotatable relative to a movable element 114a of the pivoting member 110 arranged to be movable relatively relative to the pivot axis of said pivoting member when normal operation of the pivoting member, the first element 104 of the spring 100 also being rotatable.

[0026] According to certain embodiments, the pivoting member can be subjected to the action of a single spring 100.

According to other embodiments, the pivoting member can be subjected to the action of at least two springs 100 arranged to generate a pivoting torque on the pivoting member.

[0028] Advantageously, said pivoting member is and/or cooperates with, for example, a rocker, a hammer, a lever, a rake, a finger, a slider, a hook, a wheel such as an escape wheel, a regulating organ or a source of energy.

[0029] Figure 2 shows an embodiment of a watch mechanism 1 comprising a pivoting member 11 according to the invention in which the second element 106 of the spring 100 is rotatable relative to the frame 1a of said watch mechanism during normal operation of the pivoting member, being mounted on said frame 1a.

In this example, the watch mechanism 1 is an instantaneous minute counter mechanism of a chronograph. The pivoting member 11 cooperates with a rocker 2 pivoted in O and having a sensor 3 cooperating with a cam mounted on the chronograph axis 5. The rocker 2 is held in abutment against the periphery of the cam by the return spring of Rocker 100 acting on pin 10 of a finger constituting pivoting member 11, itself acting on rocker 2.

The first rotary element 104 of the spring 100 is driven on the axis 10 of the pivoting member 11 and the second element 106 is mounted on the frame 1a so as to also be rotatable during normal operation of the pivoting member 11. The details of mounting the second member 106 to the frame 1a will be described below.

The operating details of this mechanism are described in application EP20173411.

In another variant not shown, the second element 106 is fixed relative to the frame 1a of said clock mechanism during normal operation of the pivoting member, being mounted on said frame 1a. The details of mounting the second member 106 will be described below. The operating details of this mechanism are described in publication WO 2020/016818.

In this mechanism, it is desired that the spring 100 be arranged to work in a predetermined range of winding angles, said spring being shaped to have in theory a torque C2 corresponding to a negative stiffness throughout the predetermined range in order to to compensate for the lever arm effect of the cam.

According to another embodiment of the invention shown in Figure 4, the second element 106 of the spring 100 is rotatable relative to a movable element 114 of the pivoting member 110 arranged to be relatively movable relative to the pivot axis of said pivoting member 110 during normal operation of the pivoting member 110, being mounted on said movable member 114, the first member 104 of the spring 100 also being rotatable.

In this example, the pivoting member 110 is more specifically subjected to the action of a plurality of springs 100.

[0037] In particular, the pivoting member 110 comprises a hub secured to the pivot axis (not shown) of said pivoting member 110, and an annular rim constituting the movable element 114 of the pivoting member 110.

The first rotary elements 104 of the springs 100 are all integral at least in rotation with the pivot axis of the pivoting member 110, advantageously forming a single piece which constitutes the hub of the pivoting member 110. The hub can be mounted integrally on the pivot axis, for example by driving or other equivalent means, or be made in one piece with the pivot axis of the pivoting member 110.

Each of the second elements 106 of the springs 100 is mounted on the rim 114 so as to be rotatable relative to said rim 114 during normal operation of the pivoting member 110. The details of the mounting of the second element 106 will be described below. -below. The operating details of this pivoting member are described in application EP20173411.

In another variant not shown, the second element 106 is fixed relative to the rim 114 of the pivoting member 110 during normal operation of the pivoting member 110, being mounted on said rim 114.

In this mechanism, it is desired that the springs 100 be arranged to work in a predetermined range of winding angles to generate a pivoting torque on the pivoting member 110, said springs being shaped to present in theory torques C2 corresponding to zero or negative stiffnesses throughout the predetermined range. The negative or zero stiffness of the springs 100 are chosen according to the desired application of said pivoting member 110. For example, it is desired that the springs 100 have zero stiffness so as to obtain a high constant torque C2, allowing an application as a source of energy or a very low torque C2 for regulating organ or very low energy source type applications.

The spring 100 is here considered as a whole as a part comprising the two elements 104 and 106 connected by the elastic arm 102.

In the pivoted / pivoted version as shown in Figure 1, the two elements 104 and 106 secured to the elastic arm 102 are rotatable during normal operation of the pivoting member and are intended to rotate on themselves, only the elastic arm 102 deforming during operation of the mechanism.

In the pivoted/embedded variant not shown, only the first element 104 is rotatable during normal operation of the pivoting member, and is intended to rotate on itself, the second element 106 being fixed during normal operation of the pivoting member. Only the elastic arm 102 deforms during operation of the mechanism.

The spring 100 is preferably in one piece. It is for example made of metal, alloy, silicon, plastic, mineral glass or metallic glass. It can be produced by machining or by the LIGA technique, in particular in the case where it is made of a metal or alloy, by deep reactive ion etching called DRIE, in particular in the case where it is made of silicon, by molding, in particular in the case where it is made of plastic or metallic glass, or by laser cutting, in particular in the case where it is made of mineral glass.

[0046] For the understanding of the invention, the behavior of the spring 100 considered globally and in isolation, that is to say with its two ends pivoted or pivoted/recessed, but free of any interaction with the rest of the watch mechanism to which it is associated, is described below. Figure 1 shows this isolated spring in the variant with two pivoted ends.

Due to the specific shape of its elastic arm 102, the spring 100 has a privileged direction of rotation of at least its first rotary element 104 with respect to its rest position, this direction being defined as that which allows, from a state of rest of the isolated spring 100 in which its elastic arm 102 is at rest, the greatest relative angular displacement of at least the rotary element 104 with respect to its rest position. In the variant with two pivoted ends of FIG. 1, this privileged direction of rotation is the clockwise direction for the first rotary element 104 and the counterclockwise direction for the second rotary element 106, the first rotary element 104 in white being in its position of rest, and the first rotating element 104 in black being in a constrained state after a clockwise rotation. The two rotary elements 104 and 106 pivot in the opposite direction but with different angles, which vary in particular according to the center distance between the first rotary element 104 and the second rotary element 106, that is to say the distance between the centers rotation of said rotating elements 104, 106.

θ is called the position or the angular displacement of the first rotary element 104 of the isolated spring 100 in a constrained state with respect to its rest position, θ being equal to zero when the isolated spring 100 is at rest, that is that is to say when its elastic arm 102 is at rest, and increasing with the angular displacement of the first rotary element 104, when the spring 100 is constrained, relative to its rest position in the preferred direction of rotation of said first rotary element 104 .

In general, when the first rotating element 104 is in the angular position in which θ=x°, it is said that the spring 100 is armed with x.

The spring 100 differs from conventional elastic structures. Its properties are based on a sinuous shape of its elastic arm 102 which deforms so as to generate a moment which decreases over a predetermined range of angular positions of its first rotary element 104 with respect to its rest position, the spring 100 then having a negative stiffness over said range, or a substantially constant moment over a predetermined range of angular positions of its first rotary element 104 relative to its rest position, spring 100 then having substantially zero stiffness over said range.

Obtaining such an elastic arm 102 requires a specific and parameterized design. The geometric shape of the elastic arm 102 can for example be obtained by topological optimization using parametric polynomial curves such as Bézier curves. A detailed description of this optimization method is described in the applicant's publication WO 2020/016818 to obtain an elastic arm 102 whose geometric shape is a Bézier curve or a succession of Bézier curves whose control points have been optimized to take into account, in particular, the dimensions of the spring 100 to be designed as well as obtaining a constancy of the moment of 5% over a predetermined angular range. The geometric shape of the arm 102 used in the present invention can be obtained according to the method described in said publication WO 2020/016818 to produce blades designed, in particular by their shape, to exert a substantially constant moment (constancy of 5%) in a spring comprising a pivoted end and a recessed end as detailed in said publication, but the blade obtained then being used in a spring 100 whose two ends are pivoted.

[0052] Indeed, such elastic strips can work in bending (positive stiffness) and in buckling (negative stiffness).

Any other form of curve making it possible to obtain an elastic blade which can work in bending (positive stiffness) and in buckling (negative stiffness) can be used as elastic arm in the invention.

[0054] The spring 100 can advantageously be specially shaped to have, in theory, zero or negative stiffness in at least part of the predetermined range. Such a spring 100 makes it possible at least to improve, or even guarantee, the constancy of the torque or moment of force that it exerts on the pivoting member and thus at least reduce the energy consumption.

[0055] Publication WO 2020/016818 and application EP20173411 describe different embodiments for obtaining, in theory, springs 100 shaped to have negative or zero stiffness in at least part of the predetermined range of winding angles , depending on the intended application for the pivoting member.

For example the elastic arm 102 can have a constant section or a variable section.

[0057] The predetermined range of winding angles is the predetermined range of angular positions of the first rotary element 104 with respect to its rest position,

[0058] Preferably, depending on the applications provided for the pivoting member, the spring 100 can be shaped so as to adapt its stiffness or its torque applied to the pivoting member to the function of said pivoting member with which it is associated, and by example to exhibit, in theory, zero or negative stiffness in substantially the entire predetermined range.

According to the invention, the second element 106 of the spring 100 is also arranged to be able to be movable, in particular in translation, with respect to its support (frame 1a or serge 114) prior to the normal operation of the organ 11, 110. In addition, the timepiece mechanism comprises a device 20 for moving the second element 106 relative to its support arranged to, prior to the normal operation of the pivoting member 11, 110, moving the second end 102b of the elastic arm 102, from a first position in which said spring 100 applies a torque C1 in at least part of the predetermined range to a second position in which the elastic arm has a compression or an elongation different from that of the first position so that said spring 100 applies a torque C2 different from C1 in at least part of the predetermined range.

The torque C1 corresponds for example to the original torque, obtained during assembly of the spring in the watch movement in cooperation with its pivoting member, the second end 102b of the spring being in its first position, and the torque C2 corresponds to the desired torque, the second end 102b of the spring having then been moved into its second position by the moving device.

Advantageously, the device 20 for moving the second element 106 can be operated manually by the watchmaker when mounting the pivoting member and its spring in the watch mechanism.

Advantageously, the device 20 for moving the second element 106 is arranged to move substantially in translation, and preferably in linear translation, the second end 102b of the elastic arm 102 from its first position to its second position previously normal operation of the pivoting member along a line passing through the centers of the first and second elements 104, 106.

[0063] Referring to Figure 3, in an embodiment in which the second element 106 is arranged to be rotatable relative to the support (frame 1a or rim 114) during normal operation of the pivoting member 11, 110 ( pivoted/pivoted ends configuration), the device 20 for moving the second element 106 is advantageously an eccentric comprising a base 22, a rod 24, and a head 26 eccentric with respect to the rod 24 and coaxial with the base 22, the second element 106 being pivotally mounted on the rod 24. The base 22 is mounted on the support (frame 1a or serge 114) and is arranged to be able to pivot on said support to allow adjustment of the torque or the stiffness of the spring 100 by the movement of the second end 102b of the elastic arm 102 from its first position to its second position prior to normal operation of the pivoting member 11, 110, and to be fixed relative to said support during normal operation of the pivoting member 11, 110. The eccentric is arranged to obtain a displacement in linear translation of the second end 102b of the elastic arm 102 from its first position to its second position along a line passing through the centers of rotation of the first and second elements 104, 106.

[0064] Advantageously, the head 26 is in the form of a slotted screw which indicates a "+" when aiming at the center of rotation of the first rotating element 104, which corresponds to the pivot axis 10 of the pivoting member 11 or 110, when this favors an elongation of the elastic arm 102, i.e. a behavior with positive stiffness, and a "-" when aiming at the center of rotation of the first rotary element 104, which corresponds to the axis of pivoting 10 of the pivoting member 11 or 110, when this promotes compression of the elastic arm 102, ie behavior with negative stiffness.

[0065] In the case of a pivoting member 110 with several springs 100, the screws are oriented in a coherent and balanced manner with the same orientation angle of the slot.

The eccentric may for example have an amplitude of ±0.1 mm.

[0067] More specifically, the base 22 is mounted on the support (frame 1a or serge 114) while being clamped so as to be immobile with respect to said support during normal operation of the pivoting member 11, 110, while being able to rotate on said support when the head 26 is operated by the watchmaker to adjust the torque or the stiffness of the spring 100 by moving the second end 102b of the elastic arm 102 from its first position to its second position prior to operation normal of the pivoting member 11, 110.

In one embodiment in which the second element 106 is arranged to be fixed relative to the support (frame 1a or serge 114) during normal operation of the pivoting member 11, 110 (pivoted/recessed ends configuration), and with reference to FIG. 9, the device 30 for moving the second element 106 comprises a base 31 arranged to be integral with said support. The base 31 has a housing 35 in which the second element 106 is mounted, said housing 35 comprising means for positioning and locking said second element 106 arranged to be able to position the second element 106 in different positions on the base 31 in order to move, preferably in linear translation, the second end 120b of the elastic arm 102 from its first position to its second position prior to normal operation of the pivoting member and to lock said second element 106 on the base 31 during normal operation of the member swivel 11, 110.

For example, the base 31 is U-shaped and arranged to be mounted on the support (frame 1a or serge 114), here the frame 1a, being positioned by means of two pins 32, and fixed integrally said support by means of a screw 33. The U-shaped base 31 comprises two branches 34 separated by an interior space which defines the housing 35 for the second element 106. Said second element 106 is in the form of a heel having two side tabs 36. The branches 34 of the U-shaped base 31 each have, on their opposite side face, means for positioning and locking the second element 106 comprising positioning notches 37 in which the side tabs 36 of the second element 106 s engage in order to provide different mounting positions and to lock the chosen position of said second element 106 in the U-shaped base 31, that is to say on the support 1a, during normal operation of the pivoting member. A screw 38 passing through an oblong opening 39 provided on the second element 106 and screwed onto the support, here the frame 1a, makes it possible to maintain the second element 106 in Z.

The second element 106 is mounted on the U-shaped base 31 premounted on the support 1a and is positioned in the housing 35 by choosing one or the other of the positioning notches 37 so as to move in linear translation, the second end 102b of the elastic arm 102 from its first position to its second position prior to normal operation of the pivoting member. Once the position of the second element 106 has been adjusted, the screw 38 is then screwed in so that the second element 106 is locked on the support 1a during normal operation of the pivoting member. The pivot axis of the pivoting member secured to the rotary element 104 is then mounted.

The displacement device used according to the invention makes it possible to advantageously modify in situ the behavior of the spring 100 by modifying the buckling or the flexion of the elastic arm 102 prior to the normal operation of the mechanism so as to obtain a stiffness R2 corresponding to a torque C2 in at least part of the predetermined range with a spring which originally had, when it was fitted, a stiffness R1 corresponding to a torque C1 different from the value C2 sought (the stiffness being the derivative of the torque).

[0072] For example, when the second end 102b of the elastic arm 102 is in its first position, for example during assembly, the original torque C1 applied by the spring 100 is substantially constant in at least part of the predetermined range. , which corresponds to an original stiffness R1 of substantially zero, but C1 is different from the desired torque. The device 20 for moving the second element 106 is then maneuvered in one direction, prior to normal operation of the pivoting member, to move the second end 102b of the elastic arm 102 into a second position in which said elastic arm 102 exhibits compression by relative to the first position, so that, during normal operation of the pivoting member, the torque C2 applied by the spring 100 decreases in at least part of said predetermined range, which corresponds to a negative stiffness R2, corresponding to the desired torque and stiffness, In this case, the stiffness R2 of the spring 100 will be positive in at least part of said predetermined range when the second end 102b of the elastic arm 102 is moved into a second position in which the elastic arm has a elongation relative to the first position, the displacement device 20 having been maneuvered in the other direction.

This is illustrated by Figures 5 to 8 in which the torques and stresses have been shown for a spring comprising an elastic arm of approximately 2.5 mm by applying a stress or an elongation in the longitudinal direction of the elastic arm of 0.1 mm.

[0074] Figure 5 is a graphical representation of the normalized moment exerted in a spring having its first end 102a pivoted and its second end 102b embedded, as a function of the angular displacement θ of the first rotary element 104.

The curve C1 corresponds to the original torque obtained when the second recessed end 102b of the spring is in its first position, for example after mounting the spring in the watch mechanism. The curve C2 corresponds to the torque obtained when the embedded second end 102b of the spring is in its second position, for example during normal operation of the pivoting member, the moving device 20 having been actuated to move the second end 102b prior to operation. normal of the pivoting member by causing a compression of the elastic arm 102. The curve C3 corresponds to the torque which would be obtained if the displacement device 20 were actuated to move the second end 102b prior to the normal operation of the pivoting member in the second position which would result in an elongation of the elastic arm 102.

FIG. 5 shows that, advantageously, when the spring has after assembly in the mechanism, a stiffness R1 of zero origin corresponding to the original torque C1 constant over a predetermined range [θ1, θ2]= [10°,42°] of the angular displacement θ of the first element 104, compression of the elastic arm 102 in situ by moving the end 102b of the spring by means of the displacement device 20 makes it possible to obtain, over the predetermined range [θ1 ,θ2], a negative stiffness R2 corresponding to the desired torque C2, and an elongation of the elastic arm 102 in situ by means of the displacement device 20 makes it possible to obtain a positive stiffness.

[0077] Figure 6 is a graphical representation of the normalized stress on the spring used for Figure 5 having its first end 102a pivoted and its second end 102b embedded as a function of the angular displacement θ of the first rotating element.

The curve Ct1 corresponds to the original stress obtained when the second embedded end 102b of the spring is in its first position, for example after mounting the spring in the watch mechanism. The curve Ct2 corresponds to the stress obtained when the embedded second end 102b of the spring is in its second position, for example during normal operation of the pivoting member, the displacement device 20 having been actuated to displace the second end 102b prior to the normal operation of the pivoting member by causing compression of the elastic arm 102. The curve Ct3 corresponds to the stress which would be obtained if the displacement device 20 were actuated to move the second end 102b prior to the normal operation of the pivoting member in the second position which would result in an elongation of the elastic arm 102.

[0079] Figure 7 is a graphical representation of the normalized moment exerted in a spring having its two ends 102a and 102b pivoted, as a function of the angular displacement θ of the first rotary element 104.

The curve C1' corresponds to the original torque obtained when the pivoted second end 102b of the spring is in its first position, for example after the spring has been mounted in the watch mechanism. Curve C2' corresponds to the torque obtained when the pivoted second end 102b of the spring is in its second position, for example during normal operation of the pivoting member, the displacement device 20 with eccentric according to FIG. 3 having been actuated to displace the second end 102b prior to the normal operation of the pivoting member by causing a compression of the elastic arm 102. The curve C3 corresponds to the torque which would be obtained if the displacement device 20 were actuated to move the second end 102b prior to the normal operation of the pivoting member in the second position which would result in an elongation of the elastic arm 102.

FIG. 7 shows that, advantageously, when the spring has, after assembly in the mechanism, an original stiffness R1′ of zero corresponding to the original torque C1′ constant over a predetermined range [θ1′, θ2'] = [5°,20°] of the angular displacement θ of the first element 104, compression of the elastic arm 102 in situ by moving the end 102b of the spring by means of the displacement device 20 makes it possible to obtain, on the predetermined range [θ1', θ2'], a negative stiffness R2' corresponding to the desired torque C2', and an elongation of the elastic arm 102 in situ by means of the displacement device 20 makes it possible to obtain a positive stiffness.

[0082] Figure 8 is a graphical representation of the normalized stress on the spring used for Figure 7 having its two ends 102a, 102b rotated as a function of the angular displacement θ of the first rotating element.

The curve Ct1′ corresponds to the original stress obtained when the pivoted second end 102b of the spring is in its first position, for example after mounting the spring in the watch mechanism. The curve Ct2' corresponds to the stress obtained when the pivoted second end 102b of the spring is in its second position, for example during normal operation of the pivoting member, the displacement device 20 having been actuated to displace the second end 102b previously to the normal operation of the pivoting member by causing a compression of the elastic arm 102. The curve Ct3' corresponds to the stress which would be obtained if the displacement device 20 were actuated to move the second end 102b prior to the normal functioning of the member pivoting in the second position which would cause an elongation of the elastic arm 102.

Thus, the mechanism according to the invention makes it possible to adjust in situ the stiffness and therefore the torque applied by the spring to the pivoting member, directly in the mechanism, by actuating the displacement device prior to normal operation of the pivoting member to increase or decrease the stiffness and thus obtain the desired behavior of the spring, without having to dismantle the mechanism.

Claims (13)

1. Watch mechanism (1) comprising a pivoting member mounted on a pivot axis and subjected to the action of at least one spring (100) arranged to work within a predetermined range of winding angles, said spring (100 ) comprising at least one elastic arm (102) having, at a first end (102a), a first rotary element (104) integral at least in rotation with the pivot axis of the pivoting member and, at a second end ( 102b), a second element (106) mounted on a support and arranged to be rotatable or fixed relative to said support during normal operation of the pivoting member, characterized in that the second element (106) is arranged to be able to be movable relative to said support prior to normal operation of the pivoting member and in that the timepiece mechanism comprises a device (20, 30) for moving the second element (106) relative to its support arranged to, prior to normal operation of the pivoting member, moving the second end (102b) of the elastic arm (102) from a first position, in which said spring (100) applies a torque C1 in at least part of the predetermined range, to a second position, in wherein the elastic arm (102) has a compression or an elongation different from that of the first position so that said spring (100) applies a torque C2 different from C1 in at least part of the predetermined range. 2. Timepiece mechanism (1) according to claim 1, characterized in that the displacement device (20, 30) of the second element (106) is arranged to move substantially in linear translation the second end (102b) of the elastic arm (102 ) from its first position to its second position prior to the normal operation of the pivoting member along a line passing through the centers of the first and second elements (104, 106). 3. Clockwork mechanism (1) according to one of claims 1 and 2, wherein the second element (106) is arranged to be rotatable relative to the support during normal operation of the pivoting member, characterized in that the device movement (20) of the second element (106) is an eccentric comprising a base (22), a rod (24), and a head (26) eccentric with respect to the rod (24) and coaxial with the base (22) , the second element (106) being pivotally mounted on the rod (24), and in that the base (22) is mounted on the support and is arranged to be able to pivot on the support to allow movement of the second end (102b ) of the elastic arm (102) from its first position to its second position prior to normal operation of the pivoting member and to be fixed relative to said support during normal operation of the pivoting member. 4. Clockwork mechanism (1) according to one of claims 1 and 2, wherein the second element (106) is arranged to be fixed relative to the support during normal operation of the pivoting member, characterized in that the device movement (30) of the second element (106) comprises a base (31) arranged to be integral with said support and having a housing (35) in which the second element (106) is mounted, said housing (35) comprising means for positioning and locking of said second element (106) arranged to be able to position the second element (106) in different positions on the base (31) in order to move the second end (102b) of the elastic arm (102) from its first position to its second position prior to normal operation of the pivoting member and to lock said second element (106) on the base (31) during normal operation of the pivoting member. 5. Clockwork mechanism (1) according to one of claims 1 to 4, characterized in that, when the second end (102b) of the elastic arm (102) is in its first position, the torque C1 applied by the spring (100 ) is substantially constant in at least part of the predetermined range and in that the torque C2 applied by the spring (100) decreases in at least part of the said predetermined range when the second end (102b) of the elastic arm (102) is in a second position in which the elastic arm (102) has a compression with respect to the first position. 6. Clockwork mechanism (1) according to one of the preceding claims, characterized in that the or each elastic arm (102) is of sinuous shape. 7. Clockwork mechanism (1) according to one of the preceding claims, characterized in that the geometric shape of the or each elastic arm (102) is a Bézier curve or a succession of Bézier curves. 8. Clockwork mechanism according to one of the preceding claims, characterized in that the pivoting member is subjected to the action of at least two springs (100) arranged to generate a pivoting torque on the pivoting member. 9. Clockwork mechanism (1) according to one of the preceding claims, characterized in that the pivoting member is and/or cooperates with a rocker (2), a hammer, a lever, a rake, a finger (11), a slider, a hook, a wheel, a regulating organ (110), a source of energy. 10. Clockwork mechanism according to one of the preceding claims, characterized in that the support consists of a frame (1a) of the clockwork mechanism (1). 11. Clockwork mechanism according to one of claims 1 to 9, characterized in that the support consists of a movable element (114) of the pivoting member (110) arranged to be movable relatively with respect to the pivot axis said pivoting member (110). 12. Timepiece mechanism according to claim 11, characterized in that the pivoting member (110) is subjected to the action of a plurality of springs (100) arranged to generate a pivoting torque on the pivoting member (110) , in that the pivoting member (110) comprises a hub (112) secured to the pivot axis and a rim (114) constituting the movable element of the pivoting member (110), and in that each of the second elements (106) of the springs (100) is mounted on said rim (114), the first rotating elements (104) of the springs (100) being arranged to form a single piece constituting the hub (112) of the pivoting member ( 110). 13. Timepiece comprising a timepiece mechanism (1) according to any one of claims 1 to 12.