HK1252475B - High quality factor resonator for mechanical watches - Google Patents

Description

High-quality factor resonators for mechanical watches

Technical Field

The present invention relates to a timepiece movement for a mechanical watch, comprising a resonator mechanism arranged on a main plate and an escapement mechanism that receives the torque of a drive device included in the movement, the resonator mechanism including an inertial element arranged to oscillate relative to the main plate, the inertial element receiving the action of an elastic return device directly or indirectly fixed to the main plate, and the inertial element being arranged to cooperate with an escape wheel set included in the escapement mechanism and pivoting about a main axis.

The invention also relates to a mechanical watch comprising at least one such movement.

The present invention relates to the field of resonator mechanisms forming the time base of mechanical watches.

Background Art

Most current mechanical watches consist of a balance wheel/hairspring type resonator that forms the watch's timebase and an escapement mechanism – generally known as a Swiss lever escapement – that performs two main functions:

-Maintain the reciprocating motion of the resonator;

- These reciprocating movements are counted.

The escapement must be robust, shock-resistant, and designed to avoid jamming (flashing) of the movement.

A mechanical resonator combines at least one inertial element and an elastic return element. In a sprung balance, the balance spring acts as an elastic return element for the inertial element formed by the balance wheel.

The balance wheel is typically guided in rotation by a pivot that rotates in a smooth ruby bearing. This generates friction, and thus energy losses and operational disturbances, which are sought to be eliminated. These losses are characterized by the quality factor, Q. Maximizing this factor is sought.

The Swiss lever escapement has a low energy efficiency (about 30%). This low efficiency is due to the fact that the escapement movement is jerky, with "drop clearance" (running to the swing point to accommodate manufacturing errors) and also because the multiple components transmit their motion via inclined planes that rub against each other.

European Patent Application EP 2908189 in the name of ETA Manufacture Horlogère Suisse discloses a mechanism for synchronizing two timepiece oscillators with a gear train, wherein the timepiece regulating mechanism comprises an escape wheel mounted to move at least in pivoting motion relative to a main plate, the escape wheel being arranged to receive a driving torque via the gear train, and a first oscillator comprising a first rigid structure connected to the main plate by a first elastic return device. The regulating mechanism comprises a second oscillator comprising a second rigid structure connected to the first rigid structure by a second elastic return device and including guide means arranged to cooperate with complementary guide means included in the escape wheel, thereby synchronizing the first and second oscillators with the gear train.

European patent application EP3054358 in the name of ETA Manufacture Horlogère Suisse discloses a timepiece oscillator comprising a structure and different temporarily and geometrically offset primary resonators, each comprising a weight returned towards the structure by elastic return means. The timepiece oscillator comprises coupling means for interaction between the primary resonators, comprising drive means for driving the movement of a wheel set, said wheel set comprising drive and guide means arranged to drive and guide control means, said control means being articulated with transmission means, each transmission means being articulated with a weight of a primary resonator at a distance from said control means, and said primary resonators and said wheel sets being arranged such that the axis of articulation of any two of said primary resonators is not coplanar with the axis of articulation of said control means.

Summary of the Invention

The present invention proposes an improvement in a timepiece movement combining a specific isochronous timepiece resonator mechanism and an escapement arranged relative to one another so as to improve the quality factor of the resonator, in particular by eliminating the friction associated with conventional pivots, and to increase the efficiency of the escapement by eliminating its usual jerky movements.

To achieve these objectives, the present invention proposes a resonator in which the elastic return element forms a support component, in addition to the mechanical architecture that allows continuous, jerk-free interaction between the resonator and the escape wheel. To achieve this, it is necessary to allow the resonator to utilize at least a second degree of freedom, which is out of phase with the first. To render the resonator insensitive to gravity or translational shocks, two rotational degrees of freedom are selected, whose axes pass through the center of mass of the inertial element.

The invention therefore relates to a timepiece movement for a mechanical watch comprising a resonator mechanism arranged on a main plate and an escapement mechanism subjected to the torque of a drive device included in the timepiece movement, the resonator mechanism comprising an inertial element arranged to oscillate relative to the main plate, the inertial element being acted upon by elastic return means fixed directly or indirectly to the main plate, and the inertial element being arranged to cooperate with an escape wheel set included in the escapement mechanism and pivoting about a main axis, the timepiece movement being characterized in that the escape wheel set comprises a drive device arranged to cooperate with a complementary continuous drive device included in the inertial element in the continuous transmission of movement at each angular position of the inertial element, and the elastic return means being arranged to tend to cause the complementary continuous drive device to rotate. The inertial element is arranged to return toward the main axis, and the elastic return device includes a first elastic return device around a first axis and arranged to tend to return the complementary continuous drive device toward the main axis, and a second elastic return device around a second axis and arranged to tend to return the complementary continuous drive device toward the main axis, the first axis and the second axis being perpendicular to each other and to the main axis, and the elastic return device forms a balancing frame type guide device and is arranged to prevent any movement of the inertial center of the inertial element in three linear degrees of freedom and one rotational degree of freedom, so as to allow the inertial element to be mobile in only two rotational degrees of freedom around the first axis and the second axis and around a center point forming a fixed position of the inertial center relative to the main plate.

The invention also relates to a mechanical watch comprising at least one such movement.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent upon reading the following detailed description made with reference to the accompanying drawings, in which:

1 shows a partial schematic perspective view of a movement according to the invention, comprising a resonator with a flexible gimbal and a continuous maintenance mechanism, in a variant comprising guide means distinct from elastic return means.

FIG. 2 shows a partial schematic perspective view of the Euler angles in a theoretical reference frame used for the mathematical calculation of isochronism in the following description.

- Figure 3 shows a partial schematic perspective view of a rotating single-piece articulated structure or flexible guide, here made in a non-limiting manner in the form of an elastic connection via cross bars, in a resonator according to the invention, located between the main plate and the intermediate cross piece on the one hand and between this intermediate cross piece and the inertial element on the other hand.

FIG4 shows a schematic plan view of a rotationally flexible carrier with, in particular, an elastic connection between two entities via strips crossing in projection, with a specific setting of the angles and positions of the crossing axes of the strips, thus ensuring excellent isochronism.

- Figure 5 shows a schematic perspective view of an embodiment of a carrier with crossed strips in projection, by the juxtaposition of two identical main plates mounted back to back.

FIG6 shows a schematic perspective view of a movement according to the invention, in a variant comprising a guide device combined with an elastic return device and comprising a resonator having a flexible gimbal positioned on a mainplate shown in FIG7 , with a rotationally flexible guide device, in particular with elastic connections as shown in FIG3 and in FIG8 , and an inertia element shown in FIG9 , comprising a finger cooperating with a groove in the face wheel, thereby forming an escape wheel set, and cooperating, as shown in FIG10 , via an inclined toothing, with the end of the gear train that receives the torque of the barrel (not shown in the figures).

11 and 12 show, in schematic perspective views, a movement according to another variant of the invention, further comprising a guide device combined with an elastic return device, respectively assembled in the exploded views of FIG. 11 and FIG. 12 , in which the mainplate carries, by means of rotationally flexible guides, in particular with elastic connections according to FIG. 3 , a substantially cross-shaped inertia element comprising an upper annular track on which rolls a roller housed in a groove of an escapement wheel set pivoting in a housing of the mainplate and in a bridge (not shown), wherein this roller exerts an eccentric thrust on the inertia element, causing it to perform a precessional rotational movement.

- FIG. 13 is a block diagram showing a watch including such a timepiece movement.

DETAILED DESCRIPTION

The present invention relates to a mechanical watch 1000 provided with an organic movement 500 comprising a resonator 100 mounted on a main plate 1 , the resonator having a flexible balance frame and a continuous power maintenance mechanism 200 for receiving the torque of a driving device 300 as shown in FIG. 13 .

The flexible gimbal shown in FIG. 1 and described in detail below has the function of locking the inertial element 2 and the main plate 1 of the resonator 100 in three translations and a first rotation while leaving the second and third rotations flexible.

The axis of rotation of the flexible rotation is vertical and passes through the center of mass G of the inertial element 2 of the resonator 100 .

The invention is shown here in a non-limiting manner with a single inertial element 2 .

The figures show that each mechanism has a main axis D, a first axis D1 and a second axis D2.

The general definition of Euler angles is detailed in Figure 2. The general Euler directions correspond to the physical axes according to the rules:

D = e2;

D1＝e3；

D2=n.

According to the present invention, the flexible balancing frame comprises:

at least one first rotationally flexible carrier, in particular without pivots, defining an axis of rotation D1 = e3 , embedded on one side in the base plate 1 and connected on the other side to an intermediate element 35 , known as a cross,

and at least one second rotationally flexible bearing, in particular without pivots, defining an axis of rotation n also called nodal line, connected on one side to the cross 35 and on the other side to the inertial element 2 of the resonator 100 .

According to the invention, the flexibility of each of these rotationally flexible guides induces, in relation to the rotation, a restoring torque that is proportional to the angle of rotation.

According to the invention, the inertial element 2 has an inertia matrix with substantially equal components in the directions e2 and e3 .

These two latter features make it possible to obtain isochronism of the system whatever the trajectory of the inertial element 2 .

Indeed, these features simplify the generalized Lagrangian, denoted by the cursive capital letter L and expressed here by the expression “Lag”, which is equal to the difference between the system’s kinetic energy Ec=T (total, including velocity) and its potential energy Ep=v (total, including position):

Lag(θ,φ,ψ)=T(θ,φ,ψ)–V(θ,φ,ψ)

in:

T＝

1/2I ₁ (dθ/dt.cosφ+dψ/dt.sinθ.sinφ) ²

+1/2I ₂ (-dθ/dt.sinφ+dψ/dt.sinθ.cosφ) ²

+1/2I ₃ (dφ/dt+dψ/dt.cosθ) ²

In the present invention, locking one of the rotating devices means that, in the illustrated variant, φ=0 permanently, which simplifies the expression of the Lagrangian:

Lag(θ,φ,ψ)＝

1/2I ₁ (dθ/dt) ² +1/2I ₂ (dψ/dt) ² .sin ² θ+1/2I ₃ (dψ/dt) ² .cos ² θ+1/2C _θ .θ ² +1/2C _ψ .Ψ ²

Si I2＝I 3＝I23, then we get:

Lag(θ,φ,ψ)＝1/2I ₁ (dθ/dt) ² +1/2I ₂₃ (dψ/dt) ² +1/2C _θ .θ ² +1/2C _ψ .Ψ ²

It corresponds to the Lagrangian of two synchronized oscillators in terms of θ and ψ.

The invention thus makes it possible to achieve the best possible isochronism.

In a particular embodiment, the oscillation frequencies between the angles θ and ψ can also be made equal.

In particular, the oscillation periods in the two rotations are essentially identical. That is,

FIG1 illustrates the cooperation between a finger 21 included in an inertial element 2 and a groove 41 included in an escape wheel set 4, which generally corresponds to an escape wheel included in a continuous force maintenance mechanism 200. It will be understood that, in the absence of such an escape wheel set 4, the equilibrium position of finger 21 in its free state would lie on the main axis D. The above formula ensures that, in the stable state, this finger 21 follows a circular trajectory relative to the pivot axis of escape wheel set 4.

The invention more particularly relates to a timepiece movement 500 for a mechanical watch 1000 , by applying this flexible gimbal principle.

This movement 500 includes a resonator mechanism 100 provided on a main plate 1 and an escapement 200 that receives torque from a driving device 300 included in the movement 500 .

Resonator mechanism 100 comprises at least one inertial element 2 arranged to oscillate relative to mainplate 1. This inertial element 2 is subjected to the action of elastic return means 3, 31, 32 fixed directly or indirectly to mainplate 1. Furthermore, this inertial element 2 is arranged to cooperate with an escapement wheel set 4 included in escapement mechanism 200 and pivoting about a main axis D.

According to the invention, escape wheel set 4 comprises drive means 40 arranged to cooperate with complementary continuous drive means 20 included in inertial element 2 in the continuous transmission of movement in each angular position of inertial element 2 .

Moreover, elastic return means 3 , 31 , 32 are provided so as to tend to reset the complementary continuous drive means 20 towards the main axis D.

These elastic return means 3 , 31 , 32 comprise a first elastic return means 31 arranged around a first axis D1 and tending to return the complementary continuous drive means 20 towards the main axis D, and a second elastic return means 32 arranged around a second axis D2 and tending to return the complementary continuous drive means 20 towards the main axis D.

The first axis D1 and the second axis D2 are perpendicular to each other and perpendicular to the main axis D.

Moreover, the elastic return means 3, 31, 32 form a gimbal-type guide device and are arranged to inhibit the movement of the center of inertia G of the inertial element 2 in three linear degrees of freedom and one rotational degree of freedom, so as to allow mobility of the inertial element only in two rotational degrees of freedom around the first axis D1 and the second axis D2 and around a center point forming a fixed position of the center of inertia G relative to the main plate 1.

In particular, the main axis D, the first axis D1 and the second axis D2 are collinear.

In an advantageous embodiment shown in the accompanying drawings, the first elastic return device 31 and the second elastic return device 32 are arranged in sequence, the first elastic return device 31 being arranged between the main plate 1 and the intermediate cross member 35, and the second elastic return device 32 being arranged between the intermediate cross member 35 and the inertial element 2, or vice versa.

In a particular embodiment, the first elastic return means 31, on the one hand, and the second elastic return means 32, on the other hand, are configured to apply, over at least a portion of their rotational travel, a restoring torque proportional to the angle of rotation imparted to them. More specifically, this proportionality applies to their entire angular travel. If necessary, angular limiting means are provided to limit the flexibility of these elastic return means to a range in which the restoring torque they apply is proportional to the angle of rotation imparted to them.

To obtain optimal isochronism of the resonator, the inertial element 2 has, relative to the reference system formed by the main axis D, the first axis D1 and the second axial axis D2, a diagonal inertia matrix whose entries are equal along at least two of the main axis D, the first axis D1 and the second axis D2.

More specifically, when the first elastic return device 31 and the second elastic return device 32 are arranged in sequence as shown in Figures 1, 3, 6 and 12, the first elastic return device 31 is arranged between the main plate 1 and the intermediate cross member 35, and the second elastic return device 32 is arranged between the intermediate cross member 35 and the inertial element 2, the inertial element 2 has a diagonal inertia matrix with respect to the reference system formed by the main axis D, the first axis D1 and the second axis D2, whose entries are equal along the main axis D and the first axis D1.

In the variant of Figures 1 and 6, drive means 40 comprises a substantially radial slot 41 relative to main axis D, and this radial slot 41 cooperates with a finger 21 included in complementary continuous drive means 20. In this case, the continuous maintenance mechanism comprises a finger 21 integral with inertial element 2, driven in rotation by a wheel 4 having a slot 41 which cooperates via an inclined toothing with another wheel 49 at the end of the gear train and which therefore bears the torque of drive means 300, in particular of at least one barrel. Wheel 4 here rotates about an axis perpendicular to the plane defined by the two axes of rotation in which it is flexible to rotate.

Advantageously, and as shown, the first elastic return means 31 and/or the second elastic return means 32 are formed by rotationally flexible guides lacking a pivot.

In a particular embodiment of the present invention, the first elastic return means 31 and the second elastic return means 32 together form a single member.

In a particular embodiment of the invention shown in the accompanying drawings, the first elastic return means 31 and/or the second elastic return means 32 comprise a rotationally flexible guide having two strips crossing on the same level or strips located on two nearly parallel levels and whose projections on a plane parallel to these levels cross.

In this variant of the flexible carrier with two strips, the actual or projected point of intersection of the two strips is advantageously located between 0.12 and 0.14 times their length, as shown in FIG. 4 , and the strips form an angle between them of between 60 and 80 degrees.

In another variant, the first elastic return means 31 and/or the second elastic return means 32 comprise rotationally flexible guides with RCC pivots arranged cranially and caudally.

In yet another variant, the first elastic return means 31 and/or the second elastic means 32 are doubled or, more generally, multiplied in order to increase the stiffness of the flexible gimbal in the degrees of freedom that must be involved.

In a particular variant, the first elastic return means 31 and/or the second elastic return means 32 comprise rotationally flexible guide means comprising a flexible strip made of Elinvar.

In another particular variant, the first elastic return means 31 and/or the second elastic return means 32 comprise rotationally flexible guides having flexible strips made of silicon oxide to compensate for temperature variation effects.

In another variant as shown in Figure 5, the first elastic return device 31 and/or the second elastic return device 32 includes a rotational flexible guiding device having two strips, which are strips located on two nearly parallel levels and whose projections on planes parallel to the levels intersect, each of the strips belonging to a single module 38 including the strip and its attachment device, and the flexible carrier having two strips includes two such modules 38 assembled back to back.

In a particular variant, the first elastic return device 31 and/or the second elastic return device 32 are calculated so that the first oscillation period T1 - that is, a function of the first inertia l1 and the first elastic constant k1 of the carrier in the first rotation around the first axis D1 - is equal to the second oscillation period T2, that is, a function of the second inertia l2 and the second elastic constant k2 of the carrier in the second rotation around the second axis D2.

More specifically, the first elastic return means 31 and the second elastic return means 32 have equivalent characteristics.

In a particular variant as shown in FIG. 6 , the plane defined by the first axis D1 and the second axis D2 is perpendicular to the plane of the main plate 1 and the main axis D1 is parallel to the plane D of the main plate in the equilibrium state.

In another variation shown in FIG. 11 , the plane defined by the first axis D1 and the second axis D2 is perpendicular to the plane of the main plate 1 in the equilibrium state and the main axis D1 is parallel to the plane D of the main plate.

In a variant shown in FIG11 , the drive device 40 includes a hole 42 designed to guide a roller 45. This roller 45 is arranged to roll on an annular track 250 included in the inertial element 2, which forms the complementary continuous drive device 20. The roller 45 thus applies an eccentric force to the inertial element and, in conjunction with the flexible gimbal 3, imparts a torque to the inertial element 2 that causes a precessional motion, like a coin or plate rotating on a flat surface, or a gyroscope or spinning top, due to a torque. The continuous maintenance mechanism is thus formed by a ring bearing the annular track 250 and integral with the inertial element 2, driven in precessional motion by the wheel 4 with the roller 45, which rotates about an axis perpendicular to the plane defined by the axes of rotation of the two flexible rotations.

In this respect it should be noted that a gyroscope with three rings, the middle ring of which, similar to the above-described transverse member, is connected to each of the inner and outer rings by a balancing spring, can form a resonator according to the invention.

In a particular embodiment, the first elastic return means 31 and/or the second elastic return means 32 comprise rotation guides having crossed bars and are protected against breakage following an impact due to a mechanical stop.

In a particular embodiment, the inertial element 2 comprises an inertial mass for adjusting inertia and imbalance.

The invention also relates to a timepiece, in particular a mechanical watch 100 , comprising such a movement 500 .

In short, the present invention provides certain advantages:

- The isochronism of the resonator is obtained regardless of the trajectory of the inertial element;

- the elimination of friction in the resonator pivots by replacing them with rotating flexible guides, making it possible to improve the quality factor;

- The jerky movements of the escapement are eliminated due to the continuous maintenance, making it possible to improve the efficiency of the escapement.

Claims (24)

1. A watch movement (500) for a mechanical watch (1000), comprising a resonator mechanism (100) disposed on a main plate (1) and an escapement mechanism (200) subjected to the torque of a drive device (300) included in the watch movement (500), the resonator mechanism (100) comprising an inertial element (2) configured to oscillate relative to the main plate (1), the inertial element (2) being acted upon by an elastic return device (3; 31; 32) directly or indirectly fixed to the main plate (1), and The inertial element (2) is configured to cooperate with an escape wheel assembly (4) included in the escapement mechanism (200) and pivoting about the main axis (D), characterized in that the escape wheel assembly (4) includes a drive device (40) configured to cooperate with a complementary continuous drive device (20) included in the inertial element (2) in the continuous transmission of motion at each angular position of the inertial element (2), and the elastic return device (3; 31; 32) is configured to tend to cause the complementary continuous drive device (20) to ( 20) Returns toward the main axis (D), and the elastic return device (3; 31; 32) includes a first elastic return device (31) about a first axis (D1) and configured to tend to return the complementary continuous drive device (20) toward the main axis (D) and a second elastic return device (32) about a second axis (D2) and configured to tend to return the complementary continuous drive device (20) toward the main axis (D), the first axis (D1) and the second axis (D2) being perpendicular to each other and perpendicular to the main axis (D), wherein the elastic return device (3; 31; 32) forms a balance frame type guide device and is configured to prevent any movement of the center of inertia (G) of the inertial element (2) in three linear degrees of freedom and one rotational degree of freedom, so as to allow the inertial element (2) to move about the first axis (D1) and the second axis (D2) and about the center point forming the fixed position of the center of inertia (G) relative to the main board (1) in only two rotational degrees of freedom. 2. The watch movement (500) according to claim 1, characterized in that the main axis (D), the first axis (D1) and the second axis (D2) are at the same point. 3. The watch movement (500) according to claim 1, characterized in that the first elastic return device (31) and the second elastic return device (32) are arranged sequentially, the first elastic return device (31) is arranged between the main board (1) and the intermediate cross component (35), and the second elastic return device (32) is arranged between the intermediate cross component (35) and the inertial element (2), or vice versa. 4. The watch movement (500) according to claim 1, characterized in that the first elastic return device (31) and the second elastic return device (32) are configured to apply a return torque proportional to the rotation angle applied thereto. 5. The watch movement (500) according to claim 1, characterized in that the inertial element (2) has a diagonal inertial matrix relative to a reference frame formed by the main axis (D), the first axis (D1) and the second axis (D2), wherein the terms of the diagonal inertial matrix are equal along at least two of the main axis (D), the first axis (D1) and the second axis (D2). 6. The watch movement (500) according to claim 2, characterized in that the inertial element (2) has a diagonal inertial matrix relative to a reference frame formed by the main axis (D), the first axis (D1) and the second axis (D2), the terms of which are equal along at least two of the main axis (D), the first axis (D1) and the second axis (D2), and the inertial element (2) has a diagonal inertial matrix relative to a reference frame formed by the main axis (D), the first axis (D1) and the second axis (D2), the terms of which are equal along the main axis (D) and the first axis (D1). 7. The watch movement (500) according to claim 1, characterized in that the drive device (40) of the escapement wheel assembly (4) includes a generally radial groove (41) relative to the main axis (D) and the generally radial groove cooperates with a finger (21) included in the complementary continuous drive device (20). 8. The watch movement (500) according to claim 1, characterized in that the first elastic return device (31) and/or the second elastic return device (32) are formed by a pivotless rotating flexible guide device. 9. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) together form a single component. 10. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) includes a rotating flexible guide device having two strips, the two strips either intersecting on the same level or being strips located on two nearly parallel levels whose projections intersect on a plane parallel to the levels. 11. The watch movement (500) according to claim 10, characterized in that, in the rotating flexible guide device having two strips, the actual intersection or projected intersection of the two strips is located at a position of 0.12 to 0.14 times the length of the strips, and the two strips form an angle of 60 to 80 degrees between them. 12. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) include an RCC pivot type rotating flexible guide device arranged at both ends. 13. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) are doubled to increase the stiffness of the flexible balance frame in the degrees of freedom that must be associated. 14. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) include a rotating flexible guide device having a flexible strip, wherein the flexible strip is made of Elinvar iron-nickel-chromium alloy. 15. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) include a rotating flexible guide device having a flexible strip, wherein the flexible strip is made of silicon oxide to compensate for temperature change effects. 16. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) includes a rotating flexible guide device having two strips, the two strips being strips located on two nearly parallel levels and whose projections intersect on a plane parallel to the levels, each of the strips belonging to a single module (38) including the strip and its attachment device, and the rotating flexible guide device having two strips comprising two modules (38) assembled back to back. 17. The watch movement (500) according to claim 1, characterized in that the first oscillation period (T1) is equal to the second oscillation period (T2), the first oscillation period being a function of the first inertia (l1) and the first elastic constant (k1) of the elastic return device forming the balance frame type guide device in a first rotation about the first axis (D1), and the second oscillation period (T2) being a function of the second inertia (l2) and the second elastic constant (k2) of the elastic return device forming the balance frame type guide device in a second rotation about the second axis (D2). 18. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) have the same features. 19. The watch movement (500) according to claim 1, characterized in that the plane defined by the first axis (D1) and the second axis (D2) is perpendicular to the plane of the main plate (1) in a balanced state, and the main axis (D) is parallel to the plane of the main plate. 20. The watch movement (500) according to claim 1, characterized in that the plane defined by the first axis (D1) and the second axis (D2) is parallel to the plane of the main plate (1) in a balanced state, and the main axis (D) is perpendicular to the plane of the main plate. 21. The watch movement (500) according to claim 1, characterized in that the drive device (40) of the escapement wheel assembly (4) includes a hole (42) configured to guide a roller (45), the roller being configured to roll on an annular track (250) included in the inertial element (2), the annular track forming the complementary continuous drive device (20). 22. The watch movement (500) according to claim 1, characterized in that the first elastic recovery device (31) and/or the second elastic recovery device (32) include a rotating flexible guide with intersecting strips and are protected against breakage after impact caused by mechanical stops. 23. The watch movement (500) according to claim 1, wherein the inertial element (2) comprises an inertial block for adjusting inertia and imbalance. 24. A mechanical watch (1000) comprising a watch movement (500) according to claim 1.