HK1239849A1 - Oscillator for a clock movement - Google Patents

Abstract

The invention concerns an oscillator (1) for a timepiece movement, comprising a staff (12) rigidly connected to a balance (4) carrying first and second bipolar magnets (20, 40) spaced apart from the staff (12) and capable, depending on the angular position of the balance (4), of being positioned alternately within range of a magnetic field produced by a fixed bipolar magnet (28), the latter being located on the trajectory of the first and second bipolar magnets (20, 40) and being arranged in such a way that, when one of the bipolar magnets (20, 40) approaches the fixed bipolar magnet (28), identical polarities are located opposite each other in order to produce a repulsive force. The oscillator further comprises a pallet assembly (32) and an escape wheel (30) for establishing a kinematic connection between a source of energy of the timepiece movement and the balance staff (12), and arranged in such a way that the balance (4) is capable of having a sustained periodic oscillating movement of an amplitude greater than 90 degrees.

Description

Technical Field

The present invention relates to an oscillator for a timepiece movement, comprising a shaft intended to be mounted on a movement frame element to define the rotation axis of a balance wheel including a hub connected to a suspended, angularly extended mass, carrying a first bipolar magnet arranged at a distance from the shaft, whose magnetic poles are oriented substantially along a tangential direction relative to the shaft, and which is capable, depending on the angular position of the balance wheel, of being positioned within the range of a magnetic field produced by at least one fixed bipolar magnet, which is secured to a support intended to be assembled to the movement frame. The fixed bipolar magnet is located on the trajectory of the first bipolar magnet, as defined by the pivoting of the balance wheel, and is arranged on the support in such a way that when the first bipolar magnet approaches the fixed bipolar magnet, identical polarities face each other, thereby generating a restoring torque acting on the balance wheel.

State of the art

An oscillator complying, to some extent, with the above characteristics has already been described accidentally in the DE 1789976 U utility model, which concerns various embodiments of an electromagnetic-type oscillator. The embodiment shown in Figure 2 relates to a pendulum comprising an arm, whose free end carries a magnet intended to cooperate with coils to sustain the pendulum's oscillations. The arm also carries an additional magnet in its central part, intended to cooperate with a fixed magnet, whose position is adjustable relative to the movement frame, such that a fine adjustment of the natural frequency of the oscillations can be achieved by modifying the position of the fixed magnet relative to the trajectory of the magnet carried by the pendulum arm. This document provides for the possibility of implementing a variant in which this pendulum could theoretically oscillate sustainably without the presence of the coils and therefore without the electromagnetic interaction ensuring the maintenance of the pendulum's oscillations in the embodiment shown.

The present invention relates more particularly to the field of oscillators having a balance wheel and intended for use in a portable timepiece, such as a pocket watch or a wristwatch. The balance wheel is generally associated with a spiral spring designed to generate alternating restoring torque moments in order to produce the oscillating movement.

Alternatively, the manufacturing of balance-spring oscillators is difficult to master, especially the production of spiral springs requires very specialized and rare expertise, which justifies the search for alternative solutions.

For example, the European patent EP 1805565 B1 describes various embodiments of oscillators in which restoring forces are generated by one or more permanent magnets. More specifically, this document describes the construction of an oscillator comprising a pendulum or an anchor carrying at least one movable bipolar magnet associated with at least one fixed bipolar magnet, to generate restoring forces on the pendulum or on the anchor intended to act on an oscillating element and to reproduce, in particular, the typical movement of a pendulum associated with a spiral spring, in the case of embodiments relating to pendulums. Figure 11 shows an embodiment in which a small magnetized rod fulfills the function of a pendulum.This bar is arranged in a guiding channel to perform a back-and-forth movement, being pushed from both sides by the poles of a fixed permanent magnet. The cooperation mode of the magnetized bar with an anchor located in a plane adjacent to that of the bar's movement is not clearly specified, and overall, this embodiment seems more like a concept than a practical functional implementation. The embodiment shown in Figure 15 provides that the anchor itself carries two small permanent magnets arranged to cooperate with two fixed magnets in order to generate return forces on the anchor.Such a construction is supposed to cause anchor oscillations at high frequency, which are probably difficult to maintain with good isochronism. In general, the designs proposed in this document differ from conventional constructions and require significant changes to existing watchmakers' regulators to incorporate them.

Disclosure of the invention

A main objective of the present invention is to provide a construction allowing the realization of a timepiece oscillator, as described above, without a spiral spring, and offering good chronometric performance while presenting a simple, robust structure that is not sensitive to ambient temperature variations or shocks. A further object of the present invention is to enable easy integration of the oscillator according to the invention into an existing watch movement.

For this purpose, the present invention particularly relates to an oscillator as defined in claim 1.

Preferred embodiments are defined in the dependent claims.

Thanks to these characteristics, and contrary to all expectations, the basic principle of repulsion occurring between two magnets brought close to each other, with identical polarities facing each other, allows for the generation of a restoring force suitable for implementing an oscillator for clockwork movement. Moreover, the fixed magnet directly fulfills the function of a mechanical stop, eliminating any risk of the balance wheel running away in case of shock.

Advantageously, the pendulum can be positioned substantially in a first plane, the fixed bipolar magnet being located in a second plane distinct from the first plane.

Moreover, the oscillator according to the present invention may include a swing bridge carrying a mounting bearing for the pivot of the swing shaft and to which the support of the fixed magnet is assembled.

In this case, the support can be assembled to the balance beam in such a way that its position and/or orientation can be adjusted relative to the balance beam.

According to a preferred non-limiting embodiment, it can be provided that the pendulum has a pivot arranged to cooperate with the anchor to maintain the pendulum's oscillations.

Thanks to these features, the oscillator according to the present invention can be easily implemented in conjunction with an existing watch movement, without requiring major modifications.

In general, it can be predicted that the first and second bipolar magnets are angularly spaced from each other between 20 and 180 degrees. In this case, it may be advantageous to provide that at least one of the first and second bipolar magnets is mounted on the armature in such a way that it can be moved to adjust the value of the angular gap.

The present invention also relates to a watch movement comprising an oscillator having the above-mentioned characteristics, as well as a timepiece equipped with such a watch movement.

Brief description of the drawings

Other features and advantages of the present invention will become more clearly apparent from the detailed description of a preferred embodiment that follows, made with reference to the accompanying drawings given as non-limiting examples, in which: Figure 1 represents a simplified perspective view of a watch movement comprising an oscillator according to a preferred embodiment of the invention, and Figure 2 represents a simplified perspective and exploded view of the watch movement of Figure 1.

Method(s) of implementing the invention

Figure 1 shows a simplified perspective view of a clock movement comprising an oscillator 1 according to a preferred embodiment of the present invention, while Figure 2 shows the clock movement of Figure 1 in a similar but exploded view, to highlight certain construction details.

The representation of the watch movement is simplified on the figures to facilitate the understanding of the oscillator's characteristics according to the invention.

The watch movement may be an existing caliber that would be slightly modified to incorporate the oscillator according to the invention, or alternatively, it may be a new caliber developed specifically, without departing from the scope of the invention.

The watch movement includes a frame, notably here a 2-shaped plate that is conventionally machined to support all or part of the moving parts of the movement. In particular, the plate typically supports an energy source, such as a spring housed in a barrel (not illustrated), intended to maintain the oscillations of the oscillator 1 through a going train gear (not illustrated).

Oscillator 1 includes a balance wheel 4 of generally conventional shape, meaning it comprises a hub 6 from which at least one arm 8 extends, allowing to connect a balance spring 10 to the hub.

The balance wheel 4 is fixed to an axle 12, which allows it to rotate on the movement's frame.

The first end 14 of the shaft 12 is pivoted here in a first bearing machined into the base plate 2, while the other end 16 of the shaft is pivoted in a second bearing machined on a balance beam bridge 18, which is itself assembled to the base plate 2.

According to the present invention, the balance 4 carries at least one first bipolar magnet 20, arranged away from the shaft 12. More specifically, the magnet 20 is housed in an extension 21 formed as a thickened portion on the rim 10 of the balance 4. The magnet 20 has a magnetic orientation that is substantially tangential relative to the balance 4, meaning that its first and second faces 22 and 24 have opposite polarities. For example, the first face 22 may be associated with the North pole of the magnet 20, while the second face 24 may be associated with its South pole.

Moreover, the 18th balance bridge has a support 26 arranged on the bridge in such a way that its angular orientation relative to the latter can be adjusted for a purpose that will be explained later. The support 26 carries a fixed bipolar magnet 28 arranged so that it is located close to the 10th part of the balance 4.

Thus, the first bipolar magnet 20 is capable, depending on the angular position of the pendulum 4, to be positioned within the range of the magnetic field produced by the fixed bipolar magnet 28.

Indeed, the arrangement of the support 26 on the balance wheel bridge 18 is such that the fixed bipolar magnet 28 is positioned along the trajectory of the first bipolar magnet 20, as defined by the pivoting of the balance wheel 4. This trajectory substantially has the shape of a portion of a torus adjacent to the balance wheel's staff 10 and located in a plane parallel to the latter.

In addition, the fixed bipolar magnet 28 is arranged on the support 26 such that when the first bipolar magnet 20 approaches it, identical polarities are aligned facing each other, resulting in a repulsive force. This arrangement enables the generation of restoring forces on the pendulum when it swings, intended to reproduce the typical motion of a pendulum associated with a spiral spring.

It should be noted that extension 21 may, as an alternative, be arranged radially on the sleeve 10 rather than in an axial direction, without departing from the scope of the invention. Such an alternative allows for reducing the bulk of the counterweight in the direction of its thickness, but increases its overall diameter. Of course, the shape and dimensions of the support 26 will have to be adapted to the installation of the extension 21 on the counterweight 4, and a person skilled in the art will not encounter any particular difficulties in adapting these elements according to their own needs.

Furthermore, the oscillator 1 according to the present invention comprises a coupling device, intended to establish a kinematic connection between the energy source of the watch movement and the balance wheel shaft 12, arranged in such a way that the balance wheel is capable of exhibiting a maintained periodic oscillating motion.

As mentioned above, the watch movement typically includes a gear train that connects the energy source to the oscillator.

Only the escape wheel 30, driven by the finishing gear, is shown in the figures. The escape wheel 30 continuously receives torque from its pinion (not visible), under the effect of the energy released by the power source of the watch movement, always tending to rotate it in a predefined rotational direction.

The escapement wheel conventionally cooperates with an anchor 32 pivoted on the movement's base. The anchor 32 typically includes a fork 34 arranged to cooperate with the escapement wheel 30 and a pin 36 arranged to cooperate with a stop pin (not visible) secured to the balance 4. Thus, the balance 4 periodically actuates the anchor 32 to rotate it and release the escapement wheel 30, while the latter provides small impulses back to the anchor to sustain the balance's oscillations.

Of course, other achievements are possible regarding the coupling device, without leaving the scope of the invention.

As an example, one can foresee a mechanism of the type used in bidirectional automatic winding mechanisms, which implement a simple reversing device operating with a idler gear mounted on a rocking lever, engaging alternately with a first and second gear, directly for one and via the idler gear for the other. Such a mechanism is, for example, described in the book entitled "Horology Theory" by C.-A. Reymondin et al., published by the Federation of Technical Schools (Switzerland), ISBN 2-940025-10-X, on page 178 (figs. 8-30 and 8-31). The idler gear mounted on the rocking lever switches between the gears each time the balance wheel changes direction, thus enabling energy transmission to the balance wheel at each oscillation.

The professional will be able to implement variants of the device's implementation without difficulty and without departing from the scope of the invention.

In general, it is possible to plan different implementation variants for oscillator 1.

Thus, for example, it is possible to foresee that the pendulum 4 carries a second bipolar magnet 40 housed in a second extension 41 similar to the extension 21. The second magnet 40 then has the same orientation as the first magnet 20, so that the magnets 20 and 40 alternately cooperate with the fixed bipolar magnet 28, thereby each time generating a repulsive force that reverses the direction of rotation of the pendulum 4. Moreover, providing two magnets on the pendulum makes it possible to adjust the amplitude of the pendulum's oscillations by modifying the angular spacing between the two magnets.

Preferably, an angular deviation of the order of 20 to 180 degrees can be anticipated, so that the amplitude of the pendulum's 4 oscillations is approximately between 180 and 340 degrees. Even more preferably, the angular deviation can be between 40 and 160 degrees.

Furthermore, from the figures it appears that the pendulum 4 here includes a single arm 8 with a significant angular extent to ensure balancing of the pendulum in terms of mass, especially to balance the mass of the extensions 21 and 41. Of course, other shapes and/or solutions may be selected to ensure the balancing of the pendulum, without departing from the scope of the present invention.

Regarding support 26, it may include a base 50 provided with a hole 52 to ensure its assembly to the bridge 18, from which extend first and second arms 54, 56 intended to be positioned with an appropriate angular orientation relative to the balance wheel 4, which itself is angularly oriented relative to the anchor 32 (at least, the pallet staff is positioned to provide substantially symmetrical oscillations relative to the line passing through the balance wheel shaft and the anchor's axis of rotation).

The first arm 54 allows for easier handling of the support 26 to change its angular orientation on the bridge 18, similarly to conventional escape rackets.

The second arm 56 has a housing for the fixed bipolar magnet 28, arranged here perpendicular to the main direction of the second arm 56, such that the fixed magnet 28 is finally oriented substantially tangentially relative to the balance spring 10 of the balance wheel 4.

Thanks to these characteristics and the adjustment possibilities for the orientation of the support 26, not only can the fixed magnet 28 be precisely positioned along the trajectory of the magnets carried by the pendulum, but it also allows defining a mechanical stop that provides safety against pendulum runaway in case of impact.

It should be noted that the bipolar magnets used for implementing the present invention can be made from standard magnets available on the market, and a person skilled in the art will not encounter any particular difficulty in selecting magnets suitable for their needs.

It should also be noted that the construction according to the invention allows for simplifying the design of the oscillator in reference to known solutions and further makes the oscillator less sensitive to ambient temperature variations.

The foregoing description is intended to illustrate a particular mode of implementation and the invention is not limited to the implementation of certain specific features that have just been described, such as the shapes illustrated and described for the balance or the various supports described in relation to the different magnets. It should also be noted that a person skilled in the art may also adapt the present teaching to create a linkage device between the balance and the power source of the watch movement, meeting their own needs without departing from the scope of the invention.

In general, the skilled person will not encounter any particular difficulty in adapting the content of the present disclosure to his own needs and implementing a watch oscillator comprising a balance wheel carrying at least a first magnet associated with a fixed magnet arranged on the trajectory of the magnet carried by the balance wheel, to generate a repulsion acting as a restoring force during rotation of the balance wheel, without departing from the scope of the present invention.

Claims (9)

1. Oscillator (1) for a timepiece movement, comprising a balance (4), at least one fixed bipolar magnet (28), a support (26), and a shaft (12) that is designed to be mounted on a frame element (2) of the timepiece movement so as to define the axis of rotation of said balance (4), said balance (4) comprising a hub that is as one with a suspended mass which has an angular extent and which bears a first bipolar magnet (20) that is arranged at a distance from said shaft (12), the magnetic poles of this magnet being oriented essentially along a direction that is tangential to said shaft, it being possible for this magnet, depending on the angular position of said balance (4), to be brought within range of a magnetic field produced by the at least one fixed bipolar magnet (28) which is as one with the support (26) that is designed to be joined to the frame (2) of the timepiece movement, said at least one fixed bipolar magnet (28) being arranged on said support (26) in such a way that, when said first bipolar magnet (20) moves close to said at least one fixed bipolar magnet (28), like poles are positioned facing one another so as to give rise to a return force moment acting on said balance, said suspended mass of said balance (4) bearing a second bipolar magnet (40) whose arrangement is similar to that of said first bipolar magnet (20), in such a way that said first and second bipolar magnet (20, 40) are able to alternately cooperate with said fixed bipolar magnet (28) so as to give rise to opposite respective return force moments, the oscillator comprising an anchor (32) and an escapement wheel (30) that are designed to establish a kinematic connection between a source of energy of the timepiece movement and said balance (4), and are arranged in such a way that said balance (4) can have a maintained periodic oscillating movement of amplitude greater than 90 degrees, and can periodically actuate said anchor (32), characterized in that said at least one fixed bipolar magnet (28) is positioned on the trajectory of said first bipolar magnet (20), such as this is defined by the pivoting of said balance (4).
2. Oscillator (1) according to Claim 1, said balance (4) being located essentially in a first plane, characterized in that said fixed bipolar magnet (28) is located in a second plane that is distinct from said first plane.
3. Oscillator (1) according to Claim 1 or 2, characterized in that it comprises a balance bridge (18) which bears a bearing for mounting said shaft (12) such that the latter is able to pivot, and to which said support (26) is joined.
4. Oscillator (1) according to Claim 3, characterized in that said support (26) is joined to said balance bridge (18) in such a way that its position and/or its orientation can be adjusted relative to said balance bridge (18).
5. Oscillator (1) according to one of Claims 1 to 4, characterized in that said balance (4) bears a pin that is arranged so as to cooperate with said anchor (32) in order to maintain the oscillations of said balance (4).
6. Oscillator (1) according to one of the preceding claims, characterized in that said first and second bipolar magnets (20, 40) have between them an angular spacing of between 20 and 180 degrees.
7. Oscillator (1) according to Claim 6, characterized in that at least one of said first and second bipolar magnets (20, 40) is joined to said balance (4) in such a way that it can be moved in order to adjust the value of said angular spacing.
8. Timepiece movement comprising an oscillator (1) according to one of the preceding claims.
9. Timepiece comprising a timepiece movement according to Claim 8.