Patent Application
20210124307
This application claims priority to European Patent Application No. 19205001.1 filed Oct. 24, 2019, the entire contents of which are incorporated herein by reference.
The invention relates to a device for guiding a pivoting mass in rotary pivoting.
The invention also relates to a timepiece resonator mechanism including such a pivoting guide device.
The invention also relates to a horological movement comprising such a resonator mechanism.
Horological movements generally comprise a barrel, an escapement mechanism and a mechanical resonator mechanism. The resonator mechanism comprises a spring associated with an oscillating inertia-block called a balance and a pivot. Flexible guides are now used as a spring to form a virtual pivot.
The flexible virtual pivot guides allow to significantly improve timepiece resonators. The simplest are crossed-strip pivots, composed of two guide devices with straight strips which cross each other, generally perpendicularly. These two strips can be either three-dimensional in two different planes, or two-dimensional in the same plane and are then as welded at their crossing point.
It is possible to optimise a three-dimensional crossed-strip pair for a resonator, to try to make it isochronous with an operation independent of its orientation in the gravity field, particularly in two ways (independently, or both together):
However, it is not possible to obtain a sufficient angular travel of the flexible guide for its application in a horological movement to be efficient. Indeed, the greatest angular travel is obtained when the strips cross each other in their respective middle. However, in this configuration, it is not possible to achieve sufficient isochronism. Thus, it is not possible to obtain a sufficiently stable virtual axis during the pivoting for the rotary movement of the mass to be perfectly periodic. The return torque is not entirely linear, which generates anisochronism depending on the amplitude of the mass and an error of the operation of the movement. Furthermore, the centre of mass of the mechanism shifts too much, and also causes anisochronism due to its orientation relative to gravity.
The invention seeks to avoid the aforementioned defects and aims at obtaining a flexible guide having an improved behaviour, in particular for their use in a resonator mechanism of a horological movement.
The invention thus relates to a device for guiding a pivoting mass in rotary pivoting, in particular for a horological movement.
The device is remarkable in that it comprises, arranged in series substantially in the same plane, a first support, a first pair of uncrossed strips, a second support, a pair of crossed strips and a third support, the pair of uncrossed strips comprising, a first and a second flexible strip connecting the first support to the second support without crossing each other, the pair of crossed strips including a third and a fourth flexible strip connecting the second support to the third support, the third and fourth flexible strips crossing each other between the second and the third support.
Thus, by assembling in series one of the supports separated by a pair of crossed strips and a pair of uncrossed strips, a flexible guide is obtained having, on the one hand, a sufficient angular travel, and on the other hand, an isochronism of the movement of the mass. Indeed, the second support and the pair of uncrossed strips form a first uncrossed-strip pivot, while the third support and the uncrossed strips form an uncrossed-strip pivot. However, a crossed-strip pivot generates a lack of positive linearity of the torque-angle relationship, which compensates for a lack of negative linearity generated by an uncrossed-strip pivot. Each type of pivot then induces parasitic movements opposite to each other, which cancel each other out.
Thanks to the invention, it is possible to use efficient flexible strip pivots in resonator mechanisms of horological movement. Such a device allows to keep a more stable centre of mass during the pivoting of the mass, so that the flexibility and the return torque are more linear, or else having a selected lack of linearity, for example to compensate for an escapement delay. The problems of anisochronism and operation change due to gravity are also greatly reduced, in particular in a resonator mechanism, so that mechanical horological movements are more precise.
According to a particular embodiment of the invention, the device includes a fourth support and a second pair of uncrossed strips, the second pair of uncrossed strips including a fifth and a sixth flexible strip connecting the third support to the fourth support without crossing each other.
According to a particular embodiment of the invention, the device includes a fifth and a sixth support.
According to a particular embodiment of the invention, the device includes a third and a fourth pair of uncrossed strips, the third one being mounted between the first support and the fifth support, and the fourth one being mounted between the fourth and the sixth support.
According to a particular embodiment of the invention, the fifth support is arranged between the first and the second support, and the sixth support is arranged between the third and the fourth support, when the device is at rest.
According to a particular embodiment of the invention, the fifth support is arranged beyond the first support, and the sixth one is arranged beyond the fourth support.
According to a particular embodiment of the invention, the third pair of uncrossed strips is arranged in a head-to-tail position with the first pair of uncrossed strips, and the fourth pair of uncrossed strips is arranged in a head-to-tail position with the second pair of uncrossed strips.
According to a particular embodiment of the invention, the second and the third support include arms for holding the flexible strips.
According to a particular embodiment of the invention, the first and the fourth support include arms for holding the flexible strips.
According to a particular embodiment of the invention, the fifth support is intended to be fixed, the other supports being intended to be movable, the sixth support being intended to form or support the pivoting mass.
According to a particular embodiment of the invention, the device includes two assemblies of supports and pairs of superimposed strips, one of the supports forming a support common to the two assemblies.
According to a particular embodiment of the invention, the first support is intended to be fixed, the other supports being intended to be movable, the third support being intended to form or support the pivoting mass.
According to a particular embodiment of the invention, the third support is intended to be fixed, the other supports being intended to be movable, the first support being intended to form or support the pivoting mass.
According to a particular embodiment of the invention, two flexible strips of the same pair are of equal length.
According to a particular embodiment of the invention, two strips of a pair of crossed strips cross each other substantially at their centre.
The invention also relates to a timepiece resonator mechanism including a pivoting mass arranged to rotatably pivot about a virtual pivot axis, the mechanism comprising a rotary pivoting flexible guide device according to the invention.
The invention also relates to a horological movement comprising such a timepiece resonator mechanism.
Other features and advantages of the invention will become apparent upon reading the detailed description which follows, with reference to the appended drawings, where:
The invention relates to a device for guiding a pivoting mass in rotary pivoting, for example for a resonator mechanism including a pivoting mass in a horological movement.
The three supports 2, 3, 4 here have the shape of a circular arc forming an angle comprised between 60 and 120°. The arc of the first support 2 is larger than that of the second one 3, and the third one 4 in
Of course, in variant embodiments, the supports 2, 3, 4 may have shapes that are different from those shown in the figures, for example straight shapes.
The pair of uncrossed strips 5, 6 comprises a first 5 and a second flexible strip 6 connecting the first support 2 to the second support 3. The two flexible strips 5, 6 are of the same length, and are arranged symmetrically relative to the axis A of the device 1, when the device is in the rest position. The flexible strips 5, 6 extend from the inside of the arc of the first support 2, to the outside of the arc of the second support 3. The first support 2 being larger than the second one 3, the two strips 5, 6 move towards each other while moving towards the second support 2. However, the first 5 and the second flexible strip 6 do not cross each other between the two supports. Thus, each of them is oriented in one direction, the two directions intersecting at a first virtual point 9 beyond the supports, here beyond the second support 3. The two strips are in the same plane and form therebetween an angle comprised between 5 and 130°, preferably between 25 and 110°.
The pair of crossed strips 7, 8 includes a third 7 and a fourth 8 flexible strip connecting the second support 3 to the third support 4. The third 7 and fourth 8 flexible strips are of the same length, which is here shorter than the first 5 and the second 6 strip of the pair of uncrossed strips. The third 7 and the fourth 8 flexible strip are slightly offset in height to avoid touching each other during the oscillations of the device 1. They form therebetween an angle comprised between 0° and 180°, preferably between 20° and 50°. The third 7 and the fourth 8 flexible strip cross each other at a second point 11 located between the second 3 and the third 4 support when the device 1 is at rest. Preferably, the second point 11 is arranged in the middle of the two strips 7, 8. In other words, the third 7 and the fourth 8 strip cross each other at their respective centres. Preferably, the dimensions of the strips 5, 6, 7, 8 and the supports 2, 3, 4 are selected, so that the first 9 and the second point 11 are located substantially in the same place when the device 1 is at rest, as shown in
The strips 5, 6, 7, 8 advantageously have an inertia of similar or even identical section. For example, flexible strips 5, 6, 7, 8 usually used in watchmaking in resonator mechanisms. The invention is illustrated in a particular preferred case where the flexible strips 5, 6, 7, 8 are straight. Other geometries are nevertheless considered, for example in the shape of a coil, or the like.
When the device 1 oscillates, the first support 2 remains fixed, the second support 3 oscillates thanks to the first 5 and the second 6 flexible strip at a first angle of travel, and the third support 4 oscillates thanks to the third 7 and to the fourth 8 flexible strip at a second angle of travel greater than the first angle. The oscillation takes place around a virtual axis perpendicular to the plane of device 1.
As the pair of crossed strips 7, 8 and the pair of uncrossed strips 5, 6 compensate for their defects, an isochronous oscillation is obtained, without parasitic movement of the centre of mass of the device 1. Furthermore, the angular travel of the two types of pivots is added to obtain a sufficiently large angular travel, in particular to be able to be used in a timepiece oscillation mechanism.
In a variant of this first embodiment, the third support 4 is fixed, while the first 2 and the second 3 support are movable, the first support 2 being intended to form or support the inertia-block of the oscillation mechanism. Thus, the second support 3 has an angular travel less than that of the first support 2 in this case.
According to a second embodiment, shown in
The fourth support 12 and the second pair of uncrossed strips 13, 14 are arranged by symmetry of the first pair of uncrossed strips 5, 6 and of the first support 2 relative to the axis of symmetry B of the device 1, which is perpendicular to the axis A. The axis of symmetry A of the device 1 passes through all the supports 2, 3, 4, 12, while the axis of symmetry B does not pass through the supports 2, 3, 4, 12. The second pair of uncrossed strips 13, 14 includes a fifth 13 and a sixth flexible strip 14 connecting the third support 4 to the fourth support 12 without crossing each other, in the same way that the first pair of uncrossed strips 5, 6 connects the first support 2 to the second one 3.
The directions of the strips 13 and 14 intersect at a virtual point beyond the supports 4 and 12, which is located substantially at the first and second points 9 and 11. The first 9 and the second 11 point form the centre of rotation of the device 10.
According to a first variant, the device 10 is configured so that the centre of mass of the balance is arranged on the centre of rotation of the device 10.
In a second variant, the device 10 is configured so that the centre of mass of the balance is arranged at a predefined distance from the centre of rotation of the device 10, on the axis A.
The dimensions of the pivots are selected so that the two uncrossed-strip pivots compensate for the anisochronism of the crossed-strip pivot.
In a third embodiment, shown in
The supports 3, 4, 19, 21, 2223 and the strips 5, 6, 7, 8, 17, 18, 24, 26 are superimposed in the inverted position when the device 20 is at rest. Thus, the second support 19 of the second assembly 27 is arranged above the third support 4 of the first assembly 25, and the third support 21 of the second assembly 27 is arranged above the second support 3 of the first assembly 25. Finally, the fourth support 22 of the second device 27 is arranged above the first support 2 of the first assembly 25. Thus, the fourth support 22 of the second assembly 27 oscillates above the first fixed support 2 of the first assembly 25, when the device 20 is operating.
In all these embodiments, the first support 32, 52, 72 is movable, while the fifth support 48, 58, 78 is fixed, and the sixth support 47, 57, 77 is intended to form or support the pivoting mass. Furthermore, each device 30, 40, 50 is substantially arranged in a plane.
In the fourth embodiment of
The fifth 48 and the sixth support 47 each further include a tab-shaped clip 39, 49 including two fixing holes. The tabs are disposed on the outer portion of the arc in the direction, respectively, of the first 32 and fourth supports 31. The first 35 and the second flexible strip 36 are arranged on either side of the fifth support 48, when the device is in the rest position.
The fifth and the sixth embodiment of
For the fifth embodiment, the second and third supports 53, 54 include at each end of the arc, a curved arm 59, 69 extending, respectively, around the first support 52 and the fourth support 51. Thus the four arms 59, 69 describe a deformed arc, the curvature of which is oriented towards the outside of the device 40 and is accentuated as it approaches the free end.
Each free end of the arms is connected to the first 52 or to the fourth support 51, by the first 65 and the second flexible strip 66 for the second support 53, the fifth 63 and the sixth flexible strip 64 for the fourth support 54.
In the device 50 of the sixth embodiment, the first 72 and the fourth support 71 include at each end of the arc, an arm 7989 extending, respectively, towards the fifth 78 and the sixth support 77. The four arms 79, 89 have the shape of a rectilinear segment, each free end of which is bent substantially at 90°. The two bent ends of the first support 72 are connected to the second support 73 by the first flexible strip 85 for one and the second flexible strip 86 for the other. The two bent ends of the fourth support 71 are connected to the third support 74 by the fifth flexible strip 83 for one and by the sixth flexible strip 84 for the other.
When the device 60 oscillates, all the supports 31, 32, 33, 34, 90, 91, 92, 93, 94, 98 are movable except the fifth support 48 of the first device 95. The sixth support 98 of the second assembly 99 is intended to form or support the pivoting mass.
Thanks to this mounting in series, the angular travel of the device 60 is further lengthened.
Combinations of devices mounted in series according to the fifth or the sixth embodiment are also possible.
Another type of balance 107 is shown in the resonator mechanism 80 of
The devices described in the application can be associated with a shockproof table 119, as described in the system 90 of
In all the embodiments, the strips are fixed to the supports by fixed links, for example by embedding in the support. Furthermore, the flexible strips can be strips including rigid portions and flexible portions. A strip can for example be formed of one or more rigid portions connected by flexible strips or flexible necks. A neck, for example, is a narrowing of the thickness of the rigid portion, which makes the neck flexible.
In an advantageous embodiment, the supports and the strips form a one-piece assembly. This one-piece assembly can be produced by technologies of the “MEMS” or “LIGA” type or the like, of silicon or the like, thermally compensated, in particular by a particular local growth of silicon dioxide, in some areas of the part arranged for this purpose, when this one-piece assembly is made of silicon.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19205001.1 | Oct 2019 | EP | regional |
