EP2496990B1 - Regulating member for a wristwatch, and timepiece comprising such a regulating member - Google Patents

Description

The present invention relates to a regulating organ for a wristwatch, and a timepiece for a wristwatch provided with such a movement.

The usual mechanical watches comprise an energy accumulator constituted by a barrel, a kinematic chain, or a train, driving needles, a regulating organ determining the running of the watch, and an escapement for transmitting the oscillations of the regulating organ. at the wheel. The present invention relates in particular to the regulating organ.

The regulating organs of conventional mechanical watches comprise most often a rocker mounted on a rotating axis and a return member exerting a torque on the beam to bring it back to a rest position. The escapement maintains oscillations of the balance around the rest position. The return member generally comprises a spring, the spiral, which transmits a restoring torque to the balance beam through the ferrule.

The oscillator formed by the sprung-balance pair offers remarkable properties for the measurement of time. However, it has the disadvantage of being sensitive to gravity, which tends to deform the spiral differently depending on the inclination of the watch. Moreover, the manufacture of spiral is delicate, and these organs are traditionally difficult to obtain.

Electric watches are also known whose running is regulated by an electromechanical oscillator comprising coils and magnets. For example, US4266291 discloses an oscillating mechanism for horological application based on permanent magnets and requiring a power source to energize a stator with a pulsed current. GB1175550 discloses a resonator comprising a H-shaped part provided with of oscillating magnets in a magnetic field created by coils or electrostatic elements. The oscillation frequency is determined by the geometry of the resonator.

The documents GB1380329 , US3161012 and US3670492 describe the drive of a balance wheel, consisting of two discs on which are placed magnets, by a coil exciting magnets located between the two discs. Each magnet is covered with a cylinder head to close the magnetic circuit.

In relation to these documents, an object of the present invention is in particular to propose a regulating member which can also operate in an entirely mechanical timepiece and without battery or other current source.

On the other hand, CH615314 discloses a regulating member with a balance and a conventional spiral spring; the regularity of the oscillations is improved by means of a magnet mounted on a vibrating tongue and vibrating in the magnetic field of a fixed magnet. In the same way, US2003 / 0137901 discloses a mechanical watch with magnets for detecting or correcting the position of the pendulum; the frequency of oscillations of the pendulum is, however, determined by an ordinary spiral. EP1122619 describes various embodiments of a mechanical watch whose balance is provided with magnets generating a magnetic field in fixed induction coils linked to the movement. The intensity of the current in the coils makes it possible to control the amplitude of oscillation and therefore the running of the watch. It is also suggested to correct this step in case of irregular oscillations. The movements of the balance are however stabilized by a spiral, and not by magnets.

Various documents also describe a magnetic escapement associated with a conventional regulating organ. For example, US3183426 describes a magnetic escapement for watch movement. This device uses magnets arranged on the pendulum. However, it is not suggested to remove or replace the hairspring.

In the same way, CH274901 describes different variants of mechanical exhausts associated with a conventional spiral spring regulating member.

These different solutions therefore require an additional magnetic system in addition to the spiral spring. They therefore have all the disadvantages of spiral springs, adding further complexity. An object of the present invention with respect to these various solutions is therefore to remove the spiral spring.

US3877215 describes a member which comprises a tuning fork whose vibrations are transmitted to the balance by magnetic coupling. GB1142676 describes another mechanical and magnetic oscillator with a tuning fork. CH235718 discloses a regulating member for a watch comprising an oscillating flexible rod whose end is provided with a magnet vibrating in the magnetic field of a fixed magnetic pole.

These solutions make it possible to suppress the spiral spring, but replace it with a tuning fork whose elastic deformations determine the running of the watch. The manufacture of a precise tuning fork poses similar or even more complex problems than the manufacture of a high precision hairspring.

US3621424 describes a pendulum oscillating in a magnetic field caused by a single magnet linked to the escapement. The magnet serves both the exhaust and bring the pendulum back to its equilibrium position. The pendulum, however, must be subjected to the gravitational force and can only operate in a vertical position, that is to say in a clock.

US4308605 discloses a regulating member for a timepiece provided with a vertical axis balance. Magnets make it possible to compensate for the gravitational force to compensate for the pressure differences on the two bearings and to limit the bending of the balance wheel shaft due to its own weight. The oscillations are controlled by a conventional spiral.

US5638340 relates to a table clock with a pendulum oscillating in levitation in a magnetic field, and which in a variant determines the running of the watch. The oscillating member is thus totally decoupled from the drive train of the needles. This device, however, requires a source of electrical energy to produce the levitation magnetic field and optoelectronic position control sensors of the pendulum. The mechanism is not suitable for a wristwatch.

GB615139 evokes a clock with vertical gravitational pendulum. The end of the pendulum oscillates in a circular path controlled by magnets, and thus causes the movement of the watch.

With respect to these last four documents, an object of the present invention is in particular to propose a regulating organ adapted to a wristwatch, and whose operation and running are practically independent of the gravity and the orientation of the organ. adjusting relative to the vertical.

GB644948 describes a galvanometer with a mass of inertia which is provided with two movable magnets. A permanent fixed magnet generates a magnetic field for bringing the balance back into its equilibrium position. The oscillations are maintained by a conventional anchor escapement. This solution is only sketched schematically; magnets of relatively large size are however necessary. These magnets generate a magnetic field around the regulating organ, which is likely to disrupt the operation of the device and attract parts or organs nearby.

The patent application WO2006 / 045824 in the name of the applicant, proposes to replace the spiral spring of the prior art with at least one permanent magnet which pushes the balance to its rest position against the pulses of the exhaust. The magnetic force of the magnet is independent of its orientation in space, and thus avoids the isochrononism disturbances that characterize the spiral springs when they deform under the action of gravity.

The solution described in the patent application WO2006 / 045824 employs stationary magnets relatively distant from the movable magnets on the balance, in order to push these movable magnets to the rest position at a distance. It is therefore necessary to use strong and therefore bulky magnets to generate a sufficient repulsion force. It has however been observed during tests and simulations in the context of the invention that a large part of the magnetic flux created by these magnets does not contribute to the progress of the balance, and escapes to other components of the invention. movement which it disrupts the operation.

An object of the present invention is therefore to reduce the disturbances caused by the magnetic field of the magnets on the rest of the movement.

Another object is to provide a regulating member that can operate with less powerful permanent magnets and compact.

In particular, another object of the present invention is to provide a dimensioned magnetic regulating member which can, if necessary, also be integrated in a small mechanical wristwatch movement, or even in an additional module superimposed over a movement of existing base.

Another object is to propose a regulating organ whose isochronism is improved with respect to the regulating members of the prior art.

Another aim is to propose a regulating organ that is less sensitive to shocks and accelerations than the regulating members of the prior art, in particular a regulating organ whose period is less disturbed by external shocks than known regulating devices.

Another object of the present invention is also to propose a mechanical timepiece based on a magnetic regulating member and without a spiral spring.

Another object is in particular to propose a magnetic regulating organ capable of oscillating at high frequency and which is thus suitable for very high precision and / or very high resolution time measurement, for example for mechanical chronograph applications in the tenth , hundredths or even thousandths of a second.

It is important for most watch brands to regularly offer technical innovations; this is a real challenge given the amount of published material concerning mechanical watches. An object of the present invention is therefore also to propose a regulating member for a wristwatch which is new and different from the regulating members of the prior art.

According to the invention, these objects are achieved by means of a regulating member having the features of the main claim, preferred variants being indicated in the dependent claims.

• un balancier comportant au moins un aimant permanent mobile ;
• un organe de rappel magnétique comportant au moins un aimant permanent fixe coopérant avec ledit aimant permanent mobile du balancier, de manière à générer un couple pour amener ledit balancier vers au moins une position de repos;
• un échappement pour transmettre au balancier des impulsions afin d'éloigner ledit balancier de ladite position de repos;
• au moins une culasse pour concentrer le flux magnétique d'au moins un dit aimant permanent;
• un entrefer séparant ladite culasse du balancier.

These goals are achieved in particular by means of a regulating member for a wristwatch, comprising:

• a balance comprising at least one movable permanent magnet;
• a magnetic return member comprising at least one fixed permanent magnet cooperating with said movable permanent magnet of the balance, so as to generate a torque for bringing said balance to at least one rest position;
• an escapement for transmitting impulses to the pendulum in order to move said pendulum away from said rest position;
• at least one yoke for concentrating the magnetic flux of at least one said permanent magnet;
• an air gap separating said yoke from the balance.

The use of a preferably (but not necessarily) ferromagnetic yoke makes it possible to concentrate the magnetic field created by the fixed permanent magnets and / or that created by the moving permanent magnets, and in particular to avoid disturbing the others. elements of the watch. Compared to a simple shielding, a cylinder head is advantageous because it also makes it possible to guide this magnetic field towards the place where it is used, so that the greater part of this field contributes to the reminder of the balance and to master the value and the direction of magnetic field lines in space.

In an advantageous embodiment, the stationary magnets are connected to the plate or to a bridge, and polarized so as to attract the mobile magnets of the balance to the equilibrium position. The distance between the opposite poles of the fixed and mobile magnets is therefore minimal at the rest position, so that the attraction torque to this rest position is important.

This important torque makes it possible to oscillate the balance at a high frequency, and thus to obtain an improved resolution in the measurement of time. If a very high frequency is not essential, it is also possible to reduce this torque by using permanent magnets of small volume, which allows to miniaturize the movement.

In an advantageous embodiment, the restoring torque C of the pendulum varies proportionally or substantially proportionally to the angular position Θ of the pendulum: $$\mathrm{VS}\cong \mathrm{k}\cdot \mathrm{\Theta }$$

K being a constant and Θ indicating the deflection angle of the balance relative to the rest position. This relationship is preferably true for at least a portion of the angular segment traveled by the balance during its normal oscillations, preferably for most of this segment. Thanks to this linear relationship, the organ The regulator operates in a quasi-isochronous manner, that is to say that the oscillation period is almost independent of its amplitude.

• ■ Choix particulier de la forme des aimants permanents fixes. On pourra par exemple utiliser des aimants permanents fixes de forme inhabituelle (c'est-à-dire non parallélépipédiques, non annulaires et non cylindriques), afin de contrôler précisément le champ magnétique généré dans l'espace parcouru par le balancier lors de ses oscillations. On utilisera par exemple des aimants permanents fixes dont la section radiale (dans un plan comprenant l'axe du balancier) varie de façon continue avec l'angle Θ, au moins sur une portion substantielle des aimants fixes.
  Par ailleurs, l'intensité d'aimantation peut varier de façon continue à l'intérieur du volume des aimants fixes.
• ■ De façon similaire, la forme des aimants mobiles (permanents ou ponctuels) peut également être choisie afin d'assurer cette relation non linéaire. On pourra par exemple utiliser des aimants permanents ou ponctuels de forme non parallélépipédiques, non annulaires et non cylindriques, par exemple des aimants en forme de demi-lune, afin de contrôler précisément le couple de rappel magnétique en fonction de la distance entre ces aimants mobiles et les aimants fixes. Là aussi, l'intensité d'aimantation permanente peut varier de façon continue dans le volume des aimants mobiles.
• ■ La culasse participe également à la génération du champ magnétique de rappel du balancier. Sa forme, ainsi que la forme de l'entrefer entre la culasse et le balancier, sont avantageusement choisis de manière à garantir la relation linéaire entre le couple de rappel et la déviation angulaire.

This linear relation between the torque and the angular position is obtained by one or more of the following measurements, which can be combined:

• ■ Particular choice of the shape of fixed permanent magnets. It will be possible, for example, to use fixed permanent magnets of unusual shape (that is to say non-parallelepipedal, non-annular and non-cylindrical), in order to precisely control the magnetic field generated in the space traversed by the balance during its oscillations. . For example, permanent fixed magnets whose radial section (in a plane comprising the axis of the balance) varies continuously with the angle Θ, at least over a substantial portion of the fixed magnets.
  Moreover, the magnetization intensity can vary continuously within the volume of the fixed magnets.
• ■ Similarly, the shape of moving magnets (permanent or punctual) can also be chosen to ensure this nonlinear relationship. It is possible, for example, to use non-parallelepipedal, non-annular and non-cylindrical permanent or point-shaped magnets, for example half-moon magnets, in order to precisely control the magnetic return torque as a function of the distance between these moving magnets. and fixed magnets. Here again, the permanent magnetization intensity can vary continuously in the volume of the moving magnets.
• ■ The cylinder head also participates in the generation of the magnetic return field of the balance. Its shape, as well as the form of the gap between the yoke and the balance, are advantageously chosen so as to ensure the linear relationship between the restoring torque and the angular deflection.

In one embodiment, the average amplitude of the oscillations of the balance is less than the usual amplitude of oscillations of the balance in a conventional regulating member according to the prior art. For example, the amplitude of the oscillations is less than 180 °, preferably less than 60 °, preferably less than 30 °, or even preferably less than 20 °. This reduced swing amplitude has several advantages. On the one hand, it improves the linearity of the relationship between the mechanical restoring torque of the balance and its angular position Θ; it is easier to guarantee a linear relation on a small angular segment than on a large one. Isochronism is thus improved. On the other hand, this limited amplitude facilitates the realization of high frequency oscillators, and thus improves the resolution of the regulating organ.

In one embodiment, the yoke is deformable in a calculated and optimized manner to compensate for the magnetic field variations generated by the magnets as a function of temperature. For example, the magnetic path through the cylinder head may comprise one or more air gaps whose width varies as a function of temperature, the variation being calculated and optimized for example by means of finite element calculations so as to make the magnetic field less sensitive to temperature variations.

• La figure 1 une vue de dessus d'un organe réglant selon un premier mode de réalisation.
• La figure 2 une vue en perspective d'un organe réglant selon un deuxième mode de réalisation.
• La figure 3 une vue en perspective d'un organe réglant selon un troisième mode de réalisation.
• La figure 4 une vue en coupe d'un organe réglant selon le troisième mode de réalisation.
• La figure 5 une vue en coupe d'un aimant multicouche et multimatériaux.

The invention will be better understood on reading the description of various embodiments illustrated by the figures which show:

• The figure 1 a top view of a regulating member according to a first embodiment.
• The figure 2 a perspective view of a regulating member according to a second embodiment.
• The figure 3 a perspective view of a regulating member according to a third embodiment.
• The figure 4 a sectional view of a regulating member according to the third embodiment.
• The figure 5 a sectional view of a multilayer and multimaterial magnet.

The figure 1 illustrates a top view of a regulating member for wristwatch movement, according to a first embodiment of the invention. The regulating organ mainly comprises an oscillator with a rocker 1 of which only the parts in the plane of the magnets are represented; the complete pendulum preferably includes a not shown serge mounted on the same axis 11 but in another plane.

The oscillator also includes fixed permanent magnets 2 and an escapement of which only the escape wheel 6 and a portion of the anchor 5 are shown. The exhaust 5, 6 is in this example entirely conventional, and may be constituted by a known anchor escapement. Other types of exhaust, including for example magnetic exhausts, can however also be used in this variant as well as in the other embodiments described in the application.

The pendulum 1 of the oscillator rotates about an axis 11 connected to a bridge and the plate by means of unrepresented bearings, for example incabloc bearings or magnetic bearings. In the embodiment shown, an annular portion 10 at the periphery of the balance 1 is magnetized permanently and without discontinuities all around the balance. This annular portion 10 constitutes a dipole with two opposite poles spaced in this example by 180 ° and represented symbolically with the symbols + and -.

On the variant of the figure 1 the permanent magnets 10 of the balance 1 are constituted by a ring magnetized continuously. This arrangement is advantageous because it is thus easier to obtain a return torque that varies linearly and continuously with the angular deflection Θ of the balance relative to the rest position. However, it is also possible to provide the balance 1 of several discrete magnets glued or reported, or to use a zone or a magnetization intensity which varies depending on the angular position around the balance. In another variant, the ring 10 is discontinuous, and for example provided with one or more air gaps, or magnetized with jumps / discontinuities of magnetization. The magnetization of the periphery 10 of the beam 1 can for example be obtained by magnetizing it by means of a recording head.

The regulating member of this example comprises two fixed permanent magnets 2 arranged at 180 ° from each other on either side of the balance. One of the poles of each magnet is towards the inside of the regulating organ and the opposite pole towards the outside. In addition, the polarities of the two fixed permanent magnets 2 are opposite to each other, as illustrated with symbols + and -. The reference 7 corresponds to the gap (gap) between the fixed permanent magnets 2 of the stator and the movable magnets 10 of the rotor.

In the figure, the balance 1 is shown in the rest position, and the two poles of the balance 1 are each facing the middle of the fixed magnet 2 of opposite polarity. When the rocker 1 moves away from this rest position, for example under the effect of the escapement or shock, one of the two fixed permanent magnets 2 attracts it again, while the other magnet opposite the pushes back towards this position of rest.

The fixed permanent magnets 10 advantageously have in this example a shape comprising a central portion 21 and peripheral portions 20 on either side of the central portion 21. The section of the two peripheral portions 20 in a radial plane perpendicular to the page increases. gradually moving away from the middle portion 21. It this results in a magnetic field, and therefore a mechanical return torque, which increases linearly throughout the section 20 when the rocker 1 moves away from the rest position.

• d'une part, elles permettent de contrôler la direction des lignes de champ magnétique et de s'assurer que ces lignes sont aussi rectilignes que possible le long de l'axe de symétrie du stator, en évitant les déformations qui se présenteraient immanquablement aux deux extrémités si le champ magnétique était trop faible dans cette portion 21.
• d'autre part, ces protubérances permettent de créer une zone d'attraction magnétique localisée très forte à proximité de la zone de repos souhaitée, et d'éviter ainsi que le balancier ne s'arrête vers une on plusieurs autres zones d'équilibre possibles (par exemple vers les discontinuités à la jonction entre les aimants 2 et la culasse 3).

The central portion 21 of the fixed permanent magnets 2 however forms a protuberance and thus has a large radial section. These protuberances 21 have several important effects:

• on the one hand, they make it possible to control the direction of magnetic field lines and to make sure that these lines are as rectilinear as possible along the axis of symmetry of the stator, avoiding the deformations that would inevitably occur to both. ends if the magnetic field was too weak in this portion 21.
• on the other hand, these protuberances make it possible to create a very strong localized magnetic attraction zone close to the desired resting zone, and thus to prevent the balance from stopping towards one or more other possible equilibrium zones. (for example towards the discontinuities at the junction between the magnets 2 and the cylinder head 3).

These protuberances have the disadvantage of introducing a discontinuity in the relationship between the angular deflection and the mechanical return torque; the torque increases instead of decreasing when the magnetic poles of the balance 1 are in the immediate vicinity of these protuberances 21 and that the balance approaches the rest position. This disturbance is, however, very local and nevertheless not very detrimental to isochronism, because it occurs only when the balance 1 receives the impulse of the exhaust; this pulse introduces a disturbance substantially greater than that produced by the protuberances 21, whose effect on isochronism can be neglected.

Other means than protrusions can be imagined to very locally strengthen the magnetic field near the rest positions; for example, it would be possible to further magnetize the magnets 2 at this location, or to increase their thickness.

A yoke 3 made of soft magnetic material holds and connects the two stationary magnets 2 to each other. This yoke also guides the magnetic flux between these magnets and limit the portion of the magnetic flux that escapes to other components of the watch. On the other hand, the magnetic field re-emitted by this yoke 3 also contributes to the generation of the pendulum return torque, and is used to control the direction and amplitude of this field in space. Note the substantially non-circular elliptical shape of the gap 7 between the yoke 3 and the balance 1. This form determined by calculation and numerical simulation is optimized to ensure the linearity between deflection angle and torque and in particular d ensure a significant restoring force when the rocker 1 moves away from the rest position and exceeds the angular segment of about 60 ° defined by the two permanent magnets 20. "Substantially elliptical" means here that the ellipse is deformed at both longitudinal ends by the protuberances 21; a not strictly elliptical oval shape could also be considered.

Mechanical or magnetic stops may be provided in order to limit the maximum amplitude of the oscillations of the balance 1. A magnetic stop, for example a zone of strong magnetization integral with the yoke 3, makes it possible to push the balance back towards its rest position without presenting the disadvantages of mechanical stops causing shocks likely to disturb the isochronic movement of the balance.

The figure 2 illustrates another variant of magnetic regulating member according to the invention. The pendulum 1 is made in the same way as in the example of the figure 1 and has a magnetic annular peripheral section 10. The fixed permanent magnets 2, however, have a simpler shape and comprise a single magnetic circular ring around the balance. A cylinder head 3 here in two parts surrounds this ring 2 and thus constitutes a magnetic shielding preventing the magnetic field from going out.

In this arrangement, the return torque is only very approximately proportional to the angular deflection Θ of the balance. Nevertheless, in order to guarantee isochronism, the balance 1 is forced here to perform oscillations of small amplitude over a sufficiently small angular segment so that the non-linearity can be practically neglected.

For this purpose, the regulating member comprises a reduction gear with a wheel 20 on the axis 11 of the balance and a pinion 21 actuated by the fork of the anchor 5. Thanks to this reduction, the pulses given by the exhaust 5, 6 cause a rotation of limited amplitude of the balance, so that the restoring torque is almost linear in this limited area.

A similar reduction can also be used with a regulating organ similar to that of the figure 1 , or from figure 3 for example. Furthermore, it is also possible to introduce a gear upstream of the escape wheel 6, rather than downstream as in the example; this variant reduces the friction in the regulating member, but has the disadvantage of not being able to be integrated into an existing movement without a complete redesign.

The reduction 20, 21, however, has the disadvantage of introducing additional losses by friction.

The Figures 3 and 4 illustrate another embodiment in which two permanent magnets 2 are arranged in two planes above, respectively below the plane of the balance 1. In the example, the positive pole of the upper permanent magnet 2 is directed towards the pendulum, while the negative pole of the lower permanent magnet is directed towards the pendulum. A yoke 3 connects and holds the two permanent magnets 2 and thus strengthens the magnetic field in the gap 7 between the two magnets and the balance.

The balance 1 is provided with a single magnet 10, here a non-permanent magnet (punctual magnet) made of a ferromagnetic material. This magnet forms one of the spokes connecting the periphery of the balance to its axis 11. The outer end of this radius widens into a half-moon shape. The magnetization of this magnet is therefore determined by the magnetic field generated by the two fixed permanent magnets 2. The half-moon shape of the magnetized zone 10 guarantees a return torque which varies linearly with the deflection angle with respect to the rest position (not shown).

Other variants can be imagined in the context of the invention. For example, it is possible to provide the balance 1 of one or more permanent magnets and a movable breech ferromagnetic material (or not) to direct the magnetic field between these magnets. The fixed yoke - or the bolt - can be provided with an air gap to avoid the risk of saturation of the ferromagnetic material. It is also possible to use yokes formed of ferromagnetic sheets or grains of ferromagnetic materials, in order to control the induced currents that can circulate there. In a preferred embodiment, however, will use a cylinder head in a 50-50 alloy of iron and nickel, with little magnetic hysteresis.

The variation of the magnetic field and the magnetic torque as a function of the angular deflection can also be controlled by modifying the thickness, the section in a radial plane, and / or the magnetization of the fixed or moving magnets as a function of the angular position.

In all the above variants, the accuracy of the isochronism depends in a significant way on the shape of the permanent magnets. Initial manufacturing tests with standard neodymium magnets, or other common permanent magnets, have, however, proved inconclusive, since it is difficult or expensive to machine the sintered materials that make up these materials with the required dimensional accuracy. conventional.

According to an independent characteristic of the invention, the regulating member implements permanent magnets in materials that are certainly slightly less powerful than the neodymiums and other modern materials usually used, but which have the advantage of being unsintered and available. in crystalline form; they can therefore be machined more easily with the required accuracy. In an advantageous embodiment, the magnets are based on unsintered platinum cobalt, which is one of the materials whose magnetic remanence is insensitive to temperature variations. This material also has the advantage of being slightly oxidizable, and therefore does not need to be nickel plated to protect it. Convincing tests were obtained with magnets consisting of 75 to 78% platinum (for example 76.85%) and less than 24% cobalt.

A heat treatment is preferably applied to the magnets after machining, to make it magnetizable.

Permanent magnets made of these materials can be machined with such precision that they are preferably simply driven out or mechanically held in motion; this avoids the use of glues, which disturb the direction of the magnetic field lines.

Other unsintered magnetic materials may be employed for permanent magnets, including micropowder-based magnets, plastic magnets, or other ductile magnetic alloys (Fe-Cr-Co, Remalloy, Cunife, Cunico, Vicalloy etc. ). The weak coercive field of these other materials, however, makes their use less suitable for horological applications; it is necessary to use large volumes to generate the necessary magnetic fields. On the other hand, the magnetic field produced depends very much on temperature variations.

The march of the watch is determined at least in part by the magnetic field developed by the different permanent magnets, and by the magnetic attraction force exerted on the balance. This field and this force, however, vary with each individual magnet, and it is difficult to ensure perfect reproducibility during mass production. In order to compensate for this variability, the regulating member advantageously comprises means for adjusting the position of at least one individual magnet, making it possible to adjust it to the mounting in order to adjust the running of the watch. In an advantageous embodiment, these means are for example constituted by at least one micrometer screw, or another threaded element, allowing to bring closer or to separate at least one corresponding permanent fixed magnet from the balance, in order to influence the magnetic field. exerted by this magnet on the magnetized portions of the balance. It is also possible to adjust the angular distance between two permanent magnets.

Other adjustment means may be provided, for example by adjusting the size of an air gap in the cylinder head, or by adding or displacing compensating masses on the balance.

On the other hand, temperature compensation means can also be implemented, for example by employing a conventional bimetallic balance which is deformed under the action of temperature. Alternatively, components with a high coefficient of expansion, or bimetallic components, are used to move the fixed or moving permanent magnets as a function of temperature, in particular to compensate for variations in the efficiency of the magnets when the temperature varies. .

In one embodiment, the yoke is deformable in a calculated and optimized manner to compensate for the magnetic field variations generated by the magnets as a function of temperature. For example, the magnetic path through the cylinder head may comprise one or more air gaps whose width varies as a function of temperature, the variation being calculated and optimized for example by means of finite element calculations so as to make the magnetic field less sensitive to temperature variations.

The figure 5 illustrates a sectional view of a multilayer magnet generating a magnetic field substantially independent of the temperature in the useful temperature ranges. In this example, the magnet comprises a layer 25 and another 27 polarized in the same direction and both made of a material whose magnetic remanence varies little with temperature. The intermediate layer 26 is made of another polarized material in the opposite direction and which generates a magnetic field smaller than the sum of the fields generated by the two layers 25 and 27. The magnetic remanence of the layer 26, however, varies greatly with temperature. The resulting stack of layers 25 to 27 is equivalent to a magnet polarized in the same direction as layers 25 and 27, the amplitude of the resulting field being decreased by layer 26. By judiciously choosing the materials and thicknesses of layers 25 at 27, it is thus possible to produce a magnet whose variations of remanence in the layers 25 and 27 are almost completely canceled by the variations in the layer or layers 26 polarized in the opposite direction.

The number of layers and / or materials used to make temperature-insensitive magnets may be different from the illustrative example shown on FIG. figure 4 . In one embodiment, the magnets are formed of several materials whose remanence variations compensate for each other but without arranging the layered materials. Multilayer or multi-material magnets can be used for permanent magnets as well as for mobile permanent magnets.

In one embodiment, the currents induced by the rotating magnetic field created by the rotation of the magnetic balance are used to adjust the operation of the watch. These currents can for example be measured by means of a coil connected to the movement, and their frequency or their phase used by an electronic circuit (which can itself be fed by these currents) to determine the running of the watch, and possibly correct it.

The bridges, plates, wheels and other mobile elements close to the regulating member are preferably made of a material non-magnetic in order to limit the disturbances caused by parasitic magnetic flux escaping from the body despite the breech. Magnetic shields may be provided for magnetically separating the regulating member from sensitive elements in at least some directions. Advantageously, a grounding (that is to say platinum) of the adjacent elements in which currents can be induced is advantageously provided in order to protect these elements.

The regulating organ described is particularly effective in generating high return torques, and thus high oscillation frequencies. One possible application relates for example to a regulating organ for a chronograph organ; the high oscillation frequency makes it possible to considerably improve the resolution and to mechanically time durations with a resolution of the tenth, hundredth or even thousandths of a second. For example, it is possible in the context of the invention to produce regulating members with more than 72,000 vibrations per hour, for example 360,000 vibrations, 720,000 vibrations, or more. Even if the energy dissipated by the exhaust and gear at such frequencies is important, it is not detrimental for use in a stopwatch which is intended for use for limited periods. Furthermore, it is possible to drive this high frequency regulating member with an additional barrel, for example an independent of the main barrel used for displaying the time.

High frequencies, however, require powerful magnets or very thick, which affects the desire for miniaturization.

Such a regulating member may for example be added to the main regulating member used in a wristwatch movement to give the time. The watch comprises in this case a very high resolution and very high precision regulating member dedicated to the measurement of timed durations.

This magnetic regulating member may also be mounted in the same movement as the main regulating member, or in a module auxiliary superimposed over the basic movement, for example in an additional chronograph module.

The claimed solution also has the advantage of being devoid of a spiral spring. In addition to the advantages mentioned above (supply, disturbances due to gravity etc), the removal of this organ allows to see through the regulating member, between the spokes of the beam, without the hairspring shields the components backwards. plan. It will therefore advantageously dispose the regulating organ of the invention behind an opening of the dial or in the bottom of the watch, so as to clearly show the pendulum which oscillates quickly and the components behind the pendulum.

The regulating member of the invention is preferably mounted in a movement and in a watch case revealing at least a portion of the balance, which allows the user to control his movements at any time.

Claims (15)

1. Regulating member for a wrist watch, including:

   a balance (1) comprising at least one movable magnet (10);

   a magnetic return member comprising at least one stationary permanent magnet (2) engaging with said movable magnet (10) of the balance, so as to generate a mechanical restoring torque for bringing said balance towards at least one inoperative position;

   an escapement (5, 6) for transmitting pulses to the balance so as to move said balance (1) away from said inoperative position;

   characterized by the presence of

   at least one yoke (3) made of a ferromagnetic material for concentrating the magnetic flux of at least one said permanent magnet, and

   an air-gap (7) separating said yoke (3) from the balance (1).
2. The regulating member of claim 1, wherein said mechanical restoring torque varies in an essentially continuous and linear manner depending on the angular deviation of the balance (1) relative to the inoperative position.
3. The regulating member of claim 2, wherein at least one of the magnets (2, 10) has a non-parallelepiped, non-annular and non-cylindrical shape, adapted so as to ensure the proportionality between the mechanical restoring torque and the angular deviation of the balance (1) relative to the inoperative position.
4. The regulating member of claim 3, wherein the shape of at least one stationary permanent magnet (2) is adapted so as to improve the proportionality between the mechanical restoring torque and the angular deviation of the balance (1) relative to the inoperative position and wherein the shape of at least one movable magnet (10) is adapted so as to ensure the proportionality between the mechanical restoring torque and the angular deviation of the balance (1) relative to the inoperative position.
5. The regulating member of one of the claims 2 to 4, wherein the magnetic field generated by at least one said stationary permanent magnet (2) and by the yoke (3) varies in a continuous manner along the periphery of the regulating member.
6. The regulating member of one of the claims 1 to 5, wherein the shape of the air-gap is determined so as to ensure the proportionality between the mechanical restoring torque and the angular deviation of the balance (1) relative to the inoperative position.
7. The regulating member of one of the claims 1 to 6, wherein said air-gap (7) has an essentially elliptical shape.
8. The regulating member of one of the claims 6 or 7, wherein the width of said air-gap is reduced locally by protuberances (21) to reinforce locally the magnetic field in proximity to the inoperative positions.
9. The regulating member of one of the claims 1 to 8, wherein the size of said air-gap varies depending on the temperature so as to compensate at least partly the variations of the magnetic field generated by the magnets.
10. The regulating member of one of the claims 1 to 9, including:

    two stationary permanent magnets (2) whose section grows with the angular distance relative to the inoperative position, over at least one section (20) of each of the two magnets on each side of the inoperative position (21),

    the yoke (3) connected to two permanent magnets,

    the balance (1) with a peripheral annular zone (10) that is permanently magnetized.
11. The regulating member of one of the claims 1 to 10, including:

    one or several permanent magnets (2) of annular shape around the balance;

    the yoke (3) surrounding said permanent magnets (2),

    the balance (1) with a peripheral annular zone (10) that is permanently magnetized.
12. The regulating member of one of the claims 1 to 9, including:

    the balance (1) with a permanently magnetized portion;

    a first permanent magnet (2) in a plane above the balance;

    a second permanent magnet (2) in a plane below the balance;

    the yoke (3) creating a magnetic path between said permanent magnets (2),

    wherein the section of said magnetized portion of the balance (10) varies in a continuous manner with the angular distance relative to the inoperative position.
13. The regulating member of one of the claims 1 to 12, wherein said magnets comprise several materials (25, 26, 27) arranged so that the variations of magnetic remanence depending on the temperature offset each other.
14. The regulating member of one of the claims 1 to 13, including means for adjusting the position of at least one stationary permanent magnet (2) in order to move it closer to or away from the balance (1) and thus regulate the running of the watch.
15. Mechanical watch movement including a chronograph, the running of which is determined by a regulating member according to one of the claims 1 to 14.

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