Coupled timepiece oscillators

Timepiece movement or watch including one isochronous oscillator mechanism, including only a first sprung balance oscillator including a first balance spring attached to a fixed structure at a first stud and to a first mobile component pivoting about a first axis, and a second sprung balance oscillator including a second balance spring fixed to a second mobile component, coupled to each other by mechanical connection via this second elastic return means attached to the first mobile component, this second balance spring being attached, to a felloe or an arm of the first mobile component at a second stud, and to this second mobile component which pivots about a second axis, and the maintenance of the oscillations is effected on only one of first mobile component or second mobile component.

This application claims priority from European Patent application 15201032.8 of Dec. 18, 2015, the entire disclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The invention concerns an isochronous timepiece oscillator mechanism with coupled oscillators, consisting only of a first oscillator including a first elastic return means attached, on the one hand, to a fixed structure at a first anchoring point and, on the other hand, to a first mobile component pivoting about a first axis, and a second oscillator including a second elastic return means attached to a second mobile component.

The invention also concerns a timepiece movement including at least one such oscillator mechanism.

The invention also concerns a watch including such a movement.

The invention concerns the field of timepiece oscillator mechanisms, and the regulation of motion.

BACKGROUND OF THE INVENTION

The theory of coupling oscillators is always attractive, but the implementation thereof is thwarted by problems of instability.

EP Patent 2365403 in the name of SEAGULL discloses an oscillator for a mechanical timepiece comprising a first balance freely rotating about an axis; and a balance spring connecting this first balance to a fixed point or to a second balance, the balance spring comprising: a first coil connected to the first balance and a second coil connected to the fixed point or to the second balance, and a transition section connecting the first coil to the second coil, wherein a substantially linear restoring torque for at least one balance is essentially ensured by the elastic deformation of the transition section and the coils to produce an oscillating motion for at least one balance.

CH Patent 709281 in the name of THE SWATCH GROUP RESEARCH & DEVELOPMENT describes a forced oscillation resonator arranged to oscillate at a natural frequency and comprising, on the one hand, at least one oscillating member, and on the other hand, means for maintaining oscillation arranged to exert a torque on the oscillating member, which carries at least one oscillating regulator device whose natural frequency is a regulation frequency that is comprised between 0.9 times and 1.1 times an integer multiple of the natural frequency of said resonator mechanism, the integer being greater than or equal to 2. In particular, the regulator device includes, mounted to pivot freely on the oscillating member, at least one secondary sprung balance with an eccentric unbalance with respect to the secondary pivot axis about which the secondary sprung balance pivots.

EP Patent 112633 in the name of SEIKO describes a mechanical timepiece comprising a mainspring powering the mechanical time source, and a rotational angle control mechanism formed such that, in a state where the spring is completely wound, the air resistance is applied to rotation of the balance returned by a balance spring, and, in a state where the spring is completely unwound, the air resistance is not applied to rotation of the balance with the balance spring.

CH Patent 699081 in the name of THE SWATCH GROUP RESEARCH & DEVELOPMENT describes a resonator resulting from the coupling of a first low frequency resonator with a second higher frequency resonator, wherein the first resonator includes a first inertial mass associated with a first spring, the second resonator includes a second inertial mass associated with a second spring, and wherein a third spring is disposed between the first and second inertial masses for coupling the first and second resonators.

WO Patent 2016/037717 in the name of ETA MANUFACTURE HORLOGERE SUISSE discloses a regulator comprising, mounted to move in at least a pivoting motion with respect to a plate, an escape wheel arranged to receive a drive torque via a gear train, a first oscillator comprising a first rigid structure connected to the plate by first elastic return means. This regulator also comprises a second oscillator with a second rigid structure connected to the first rigid structure by second elastic return means, which are arranged to allow at least a pivoting motion of the second rigid structure with respect to the first rigid structure. The second structure comprises guide means arranged to cooperate with complementary guide means comprised in the escape wheel, together forming a motion transmission means for synchronizing the first oscillator and the second oscillator with the gear train.

SUMMARY OF THE INVENTION

The invention proposes to define simplified coupled oscillators, which make it possible to obtain good mode stability and which are easy to produce.

The invention thus concerns an isochronous timepiece oscillator mechanism with coupled oscillators according to claim1.

The invention also concerns a timepiece movement including at least one such oscillator mechanism.

The invention also concerns a watch including a movement of this type.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention concerns an isochronous timepiece oscillator mechanism100with coupled oscillators, which is achieved very simply, by the combination of only two primary oscillators: this oscillator mechanism100consists only of a first oscillator10and a second oscillator20.

We name in the present description a “mobile component” any component able to pivot around a pivot axis, namely a wheel set in a non-limiting embodiment.

First oscillator10includes a first elastic return means11, which is attached, on the one hand, to a fixed structure1at a first anchoring point12, and on the other hand, to a first mobile component13pivoting about a first axis D1.

Second oscillator20includes a second elastic return means21attached to a second mobile component23.

According to the invention, first oscillator10and second oscillator20are coupled to each other, by aerodynamic connection between first mobile component13and second mobile component23and/or by mechanical connection via second elastic return means21, which is then attached to first mobile component13.

In particular, there is only one first elastic return means11and only one second elastic return means21.

More particularly, first oscillator10and second oscillator20are coupled to each other, both by aerodynamic connection between first mobile component13and second mobile component23, and by mechanical connection via second elastic return means21which is attached to first mobile component13.

In a particular embodiment of the invention, second elastic return means21is a monolithic articulated structure or flexible bearing with thin strips.

In a particular and non-limiting embodiment of the invention, first oscillator10is of the sprung balance type, and first elastic return means11is a first balance spring attached to fixed structure1by a first balance spring stud forming first anchoring point12. Second oscillator20is also of the sprung balance type, and a second elastic return means21is a second balance spring attached to a second mobile component23.

In other embodiments of the invention, first elastic return means11, and/or second elastic return means21for coupling, is a thin resilient strip, or similar.

In a particular variant of this embodiment comprising balance springs, second spring21is attached, on the one hand to the rim or to an arm of first mobile component13at a second balance spring stud22, and on the other hand, to second mobile component23, which pivots about a second axis D2. Maintenance of the oscillations of oscillator mechanism100is effected on only one of the first mobile component13or the second mobile component23.

In another variant, maintenance of the oscillations is effected independently on each of the two primary oscillators10and20.

More particularly, the rigidity of the second elastic return means21is less than half the rigidity of first elastic return means11.

More particularly still, the rigidity of second elastic return means21is comprised between 0.30 and 0.40 times the rigidity of first elastic return means11.

More particularly, the inertia of second mobile component23is less than one third of the inertia of first mobile component13.

More particularly still, the inertia of second mobile component23is comprised between 0.20 and 0.30 times the inertia of first mobile component13.

In a particular embodiment, first mobile component13and second mobile component23are balance wheels.

In another particular embodiment, first mobile component13or second mobile component23is a carriage of a tourbillon or a karussel, and second mobile component23or respectively first mobile component13is a balance wheel.

More particularly, the balance wheel forming second mobile component23, or respectively first mobile component13, is coaxial to the tourbillon or karussel carriage forming first mobile component13, or respectively second mobile component23, and is pivoted inside the carriage. The second balance spring stud22of second oscillator20is attached to an arm or to a drum of the carriage. Maintenance of the oscillations of oscillator mechanism100is effected by a pallet lever3or a detente cooperating with a small roller attached to the tourbillon or karussel at the pivot axis thereof.

In a particular embodiment, which is advantageous for permitting aerodynamic coupling, the minimum distance G between parts of large diameter, particularly the parts of largest diameter, of first mobile component13and of second mobile component23is less than 0.5 mm. This aerodynamic coupling is advantageous, even when a main coupling is achieved by second elastic return means21, since the aerodynamic coupling tends to stabilise oscillator mechanism100over only one of the two modes (inphase or in phase opposition). An aerodynamic coupling exists even with discontinuous services, for example between the arms4of a tourbillon or karussel carriage on the one hand, and a balance rim5on the other.

Advantageously, oscillator mechanism100includes means for varying this distance between first mobile component13and second mobile component23, preferably within the range 0.1 to 0.5 mm.

FIG. 5is a diagram roughly illustrating the shape that the phase shift curve can take as a function of time, demonstrating that, at a certain value, notably close to 0.5 mm, the phase shift stabilises at a substantially constant value. Of course, a certain transitional regime duration ΔT is required before reaching stabilisation, for example around 200 seconds for an oscillator consisting of two conventional timepiece sprung balances, oscillating at 3 Hz, where the balances are coplanar and separated by 0.5 mm.

In a particular embodiment, second mobile component23and first mobile component13are coaxial.

In another particular embodiment, at least in projection, second mobile component23is inside first mobile component13.

In another particular embodiment, the parts of greatest diameter of first mobile component13and of second mobile component23, which are positioned on two different stages, are of substantially the same diameter and substantially opposite each other.

In this latter variant, and with no particular embodiment, the second elastic return means21is a second balance spring which extends over two stages.

In yet another particular embodiment, second mobile component23and first mobile component13are positioned side-by-side and are substantially coplanar.

FIG. 9shows an aerodynamic coupling with washers or balls or similar, disposed between two balances. This solution is also applicable to a variant of theFIG. 8solution, with a third mobile component positioned between the two balances. More particularly, at least a third mobile component is inserted between the parts of largest diameter of first mobile component13and of second mobile component23, this third mobile component having only the freedom to pivot on itself or to slide in a direction orthogonal to the straight line that defines the minimum distance between the parts of largest diameter of first mobile component13and of said second mobile component23. More particularly still, the third mobile component is attached to a third elastic return means independent of the first elastic return means and of the second elastic return means to define a third oscillator, coupled by aerodyanic connection to first oscillator10and to second oscillator20.

The insertion of one or more mobile components ensures the stabilisation of the system of two coupled oscillators in the anti-phase mode, which has a higher frequency. Each of these mobile components can be connected to an independent elastic return means, thereby imposing a regular oscillation of the mobile component. In the case of balance wheels, such a variant can be achieved in a MEMS type or similar embodiment, made of micromachinable material, of the silicon or other type, with integrated flexible bearings.

The invention also concerns a timepiece movement200including at least one such oscillator mechanism100.

The invention also concerns a watch1000including a movement200of this type.