EP2784602B1 - Arbour of a mobile with optimised geometry in magnetic environment - Google Patents

Arbour of a mobile with optimised geometry in magnetic environment Download PDF

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Publication number
EP2784602B1
EP2784602B1 EP13161123.8A EP13161123A EP2784602B1 EP 2784602 B1 EP2784602 B1 EP 2784602B1 EP 13161123 A EP13161123 A EP 13161123A EP 2784602 B1 EP2784602 B1 EP 2784602B1
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EP
European Patent Office
Prior art keywords
pivot axis
balance
field
magnetization
shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP13161123.8A
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German (de)
French (fr)
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EP2784602A1 (en
Inventor
Alain Zaugg
Davide Sarchi
Polychronis Karapatis (Nakis)
Marco Verardo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Montres Breguet SA
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Montres Breguet SA
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Publication date
Priority to CH00665/13A priority Critical patent/CH707791B1/en
Application filed by Montres Breguet SA filed Critical Montres Breguet SA
Priority to EP13161123.8A priority patent/EP2784602B1/en
Priority to PCT/EP2014/055268 priority patent/WO2014154511A2/en
Priority to CN201480018602.8A priority patent/CN105074585B/en
Priority to EP14713783.0A priority patent/EP2979140B1/en
Priority to US14/779,883 priority patent/US9372473B2/en
Priority to JP2016504561A priority patent/JP6034991B2/en
Publication of EP2784602A1 publication Critical patent/EP2784602A1/en
Priority to HK16105565.6A priority patent/HK1217774A1/en
Application granted granted Critical
Publication of EP2784602B1 publication Critical patent/EP2784602B1/en
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    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/32—Component parts or constructional details, e.g. collet, stud, virole or piton
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B31/00—Bearings; Point suspensions or counter-point suspensions; Pivot bearings; Single parts therefor
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B13/00—Gearwork
    • G04B13/02—Wheels; Pinions; Spindles; Pivots
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B15/00—Escapements
    • G04B15/14—Component parts or constructional details, e.g. construction of the lever or the escape wheel
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G04B17/06—Oscillators with hairsprings, e.g. balance
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G04B17/06—Oscillators with hairsprings, e.g. balance
    • G04B17/063—Balance construction
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B43/00—Protecting clockworks by shields or other means against external influences, e.g. magnetic fields

Definitions

  • the invention relates to a mechanism comprising a mobile, comprising a shaft, intended to pivot about a pivot axis and comprising at least one projecting part of greater radius about said pivot axis, said shaft being made of steel, said oscillating mobile around a rest position defined by a rest plane passing through said pivot axis, said mobile being biased towards said rest position by elastic return means, said mechanism having a preferred direction of magnetization.
  • the invention also relates to a watch movement comprising at least one such mechanism.
  • the invention also relates to a watch comprising at least one such watch movement, and / or comprising at least one such mechanism.
  • the invention relates to the field of watch mechanisms, in particular the field of regulating members, in particular for mechanical watches.
  • the regulating organ of a mechanical watch is constituted by a harmonic oscillator, the sprung balance, whose oscillation natural frequency depends mainly on the inertia of the balance and the elastic rigidity of the spiral.
  • the oscillations of the sprung balance, otherwise damped, are maintained by the pulses provided by an escapement generally composed of one or two pivoting mobiles.
  • these pivoting mobiles are the anchor and the escape wheel.
  • the march of the watch is determined by the frequency of the sprung balance and by the disturbance generated by the impulse of the escapement, which generally slows down the natural oscillation of the sprung balance and thus causes a delay in running.
  • gait defects related to the residual effect of the field
  • the origin of these defects is permanent magnetization fixed ferromagnetic components of the movement or the covering and the permanent or transient magnetization of the moving magnetic components forming part of the regulating member (balance spring) and / or the escapement.
  • magnetically or magnetically permeable mobile components (balance, hairspring, exhaust) are subjected to magnetostatic torque and / or magnetostatic forces.
  • these interactions modify the apparent rigidity of the sprung balance, the dynamics of the escape mobiles and the friction. These modifications produce a fault that can range from a few tens to a few hundred seconds a day.
  • the interaction of the watch movement with the external field, during the exhibition, can also lead to the stop of the movement.
  • the arrest in the field and the residual run-out are not correlated, because the arrest in field depends on the transient magnetization, sub-field, of the components (and therefore of the permeability and the saturation field). components), while the residual run fault depends on the residual magnetization (and therefore, mainly, the coercive field of the components) which can be low even in the presence of a significant magnetic permeability.
  • the anchor body and the escape wheel can be made of very low paramagnetic materials, without their mechanical performance being affected.
  • the shafts of the mobiles require very good mechanical performances (good tribology, low fatigue) to allow an optimal and constant pivoting in the time, and it is therefore preferable to manufacture them in hardened steel (typically carbon steel type 20AP or the like).
  • hardened steel typically carbon steel type 20AP or the like.
  • such steels are materials sensitive to magnetic fields because they have a high saturation field combined with a high coercive field.
  • the balance, anchor and escape wheel shafts are currently the most critical components in the face of the magnetic disturbances of the watch.
  • the balance shaft is the most sensitive component for chronometry (residual effect), because a disturbing torque of magnetic origin acting on the shaft directly modifies the oscillation frequency of the balance-spring, and this modification is, in principle, unlimited (it depends solely on the intensity of the residual magnetic fields and the rigidity of the hairspring), while a disturbance of the exhaust function gives a defect limited by the delay nominal exhaust (the resulting disturbance can not be much larger than the disturbance already produced by the exhaust under normal conditions).
  • the document FR 2 275 815 A1 NIVAROX describes the manufacture of a balance shaft from a profile with several wings distributed around the pivot axis., And a variant with two curvilinear wings.
  • the document FR 2 090 784 A5 FEINMETALL describes the assembly of a spiral to a balance having a crossbar with two substantially symmetrical wings.
  • the document JP S62 63884 A ZENKOSHA TOKEI describes the machining by cutting a balance with two wings.
  • the document WO 01/77759 A1 DETRA describes an escapement device comprising a gear train for transmitting energy to an oscillator capable of receiving this energy and transmitting an oscillation frequency, and first means capable of producing at least a first portion of the energy transmitted by this gear train and intended to feed the oscillator, where the first means are configured so as to provide a substantially variable mechanical torque as a function of the angular displacement angle of the gear train, this mechanical torque having at least one stable position, and at least one an unstable position, over a period of angular displacement of the gear train.
  • these first means produce a variable magnetic torque as a function of time, by the combination of a magnetized rotor diametrically, with a stator having cells at its bore receiving this rotor.
  • the invention proposes to limit the magnetic interaction on a mobile shaft, in particular on a balance shaft.
  • the invention relates to a mechanism according to claim 1.
  • said mechanism is an escape mechanism
  • said mobile is a pendulum brought to said rest position by at least one spiral spring
  • said shaft is a balance shaft
  • the invention also relates to a watch movement comprising at least one such mechanism.
  • the invention also relates to a watch comprising at least one such watch movement, and / or comprising at least one such mechanism.
  • the invention more particularly the field of clocking devices for mechanical watches.
  • the invention proposes to limit the magnetic interaction on a mobile shaft, in particular on a balance shaft.
  • the invention thus relates to a mobile shaft with optimized geometry in a magnetic environment.
  • the invention can allow watches with spiral, anchor body and nonmagnetic escape wheel to resist, without stopping, magnetic fields of high intensity, of the order of 0.5 Tesla, without the mechanical performances (chronometry and aging of the mobiles) are affected.
  • the implementation of the invention makes it possible to reduce the residual effect of watches with spiral, anchor body and non-magnetic escape wheel to less than one second per day.
  • axis refers to a virtual geometric element such as a pivot axis, and “shaft” to a real mechanical element, made in one or more parts.
  • a pair of pivots 2A and 2B aligned and reported on either side of a median portion 6 of a mobile 10, to guide it in pivoting is also called “tree”.
  • magnetically permeable materials are defined as materials having a relative permeability that is between 10 and 10,000, such as steels, which have a relative permeability close to 100 for balance shafts for example, or close to 4000 for steels commonly used in electrical circuits, or other alloys whose relative permeability reaches values from 8000 to 10000.
  • Magnetic materials for example in the case of polar masses, will be called materials capable of being magnetized so as to have a residual field of between 0.1 and 1.5 Tesla, such as for example the "Neodymium Iron Boron". a magnetic energy density Em close to 512 kJ / m 3 and giving a residual field of 0.5 to 1.3 Tesla. A lower residual field level, towards the lower part of the range can be used when combining, in a magnetization couple, such a magnetic material with a magnetically permeable antagonist component of high permeability, closer to 10000, in the range of 100 to 10,000.
  • Magnetic materials will be referred to as materials having a relative magnetic permeability of between 1.0001 and 100, for example for spacers interposed between a magnetic material and a magnetically permeable antagonist component, or alternatively between two magnetic materials, for example a spacer between a component and a polar mass.
  • weakly paramagnetic materials are: aluminum, gold, brass or the like (magnetic permeability less than 2).
  • Magnetic materials will be referred to as materials of relative magnetic permeability less than 1 (negative magnetic susceptibility, less than or equal to -10 -5 ), such as graphite or graphene.
  • soft magnetic materials not to say non-magnetic, especially for shielding, materials with high permeability but high saturation, because we do not want them to be permanently magnetized: they must drive the best possible the field, so as to reduce the field to their outside. Such components can then also protect a magnetic system from external fields.
  • These materials are preferably chosen to have a relative magnetic permeability of between 50 and 200, and with a saturation field greater than 500 A / m.
  • Non-magnetic have a relative magnetic permeability very slightly greater than 1, and less than 1.0001, as typically silicon, diamond, palladium and the like. These materials can generally be obtained by MEMS technologies or by the "LIGA” process.
  • the invention relates to a watchmaking tree 1, for a mobile 10, and optimized for the operation of this mobile 10 in an environment where there is a residual magnetic field in a preferred direction of magnetization DAP.
  • this mobile 10 is a pendulum.
  • the person skilled in the art will be able to extrapolate the invention to other watchmobiles for which he wishes to avoid the influence of a residual magnetic field.
  • a standard balance shaft 1 relatively standard in the watch industry, is not optimized to limit its magnetization under an external field.
  • the median part 6 of the shaft 1, having a larger radius RMAX is strongly magnetized by a magnetic field orthogonal or oblique with respect to the direction of the pivot axis D. Because of this magnetization, in presence of an environmental field (external field or created by the magnetized components of the movement or the watch), the shaft 1 is subjected to a large magnetic torque.
  • the rocker 10 is part of an escapement mechanism 20, in a movement 30 of a watch 40.
  • the invention proposes to modify the geometry of the balance shaft 1, by modifying the aspect ratio of the so-called projecting part 11, which is the part of larger radial size of this balance shaft, by giving it, in projection on a plane perpendicular to the pivot axis D of the shaft 1 of the balance 10, a form ratio very different from 1, preferably greater than or equal to 2.
  • the idea is to reduce one of the two dimensions x or y (in projection in a plane perpendicular to the pivot axis D), the simplest way is to locally limit the shaft 1 by two surfaces 14, 15, substantially parallel to the axis D, which surfaces 14 and 15 are preferably two planes parallel to the axis D; indeed, if the surfaces, especially the planes, are not parallel, then there remains a larger part which can be magnetized more than the rest.
  • These two surfaces 14 and 15 are preferably very close to each other, to reduce the magnetization in this direction, and to well define a single preferred direction of magnetization in the xy plane.
  • the projection of this projecting portion 11 along a plane perpendicular to the pivot axis D of the balance 10, has a profile 12, which is inscribed in a rectangle R symmetrical with respect to two orthogonal axes, of which a principal axis DP according to which extends the largest dimension of this protruding portion 11.
  • the aspect ratio is the ratio between the two dimensions of the rectangle, length LR and width LA.
  • the balance shaft 1 has no revolution symmetry.
  • this main axis DP which extends the largest dimension of this projecting portion 11 is in the orthogonal position relative to the direction of preferential magnetization DA of the environment some movement.
  • This main axis DA is generally determined by bridges, bars, screws, or the like; it depends directly on the construction and generally it is quite obvious, by the examination of the form factor of the steel components near the axis; in ambiguous situations, it is sufficient to perform a finite element simulation or equivalent loads to determine it easily.
  • This so-called “rest” position of the balance corresponds to that it occupies when the hairspring is at rest: this is the position in which the movement is the least often, but, as explained in the rest of the presentation, is the position medium and, for very strong external fields, it is the position that defines the resulting magnetization.
  • the balance plate has its largest dimension perpendicular to the exhaust line, which makes it possible to maximize the surface effects in the face of the volume effects, so as to minimize magnetization in the direction of rotation. field and, hence, the "compass" effects that create a disruptive couple.
  • the figure 1 shows a pendulum shaft 1 with a magnetically optimized realistic geometry.
  • the widest portions, which are used as a support, have an important aspect ratio, the largest dimension being oriented with its main axis DP in the direction orthogonal to the direction of preferential magnetization DA of the environment of the movement.
  • This tree 1 is drawn on a conventional balance-shaft base, with spans turned pivots, supports: ferrule support, serge, plate, double tray, or others.
  • the portion of larger diameter 11 serves to support a face of a serge 50, not shown in the figure, the shaft 1 having a bearing surface 13 of this serge;
  • the profile 12 is here produced by machining, in particular by milling or turning, or the like, of two opposing surfaces 14 and 15, as also visible on the figure 6 these surfaces are planar surfaces in a simplified and preferred embodiment.
  • the figure 2 shows a balance shaft 1 with magnetically optimized geometry schematized.
  • the widest portions which are used as a support, have an important aspect ratio, the largest dimension being oriented with its main axis DP in the direction orthogonal to the direction of preferential magnetization DA of the environment of the movement. If certain spans, including the pivots, remain of revolution, the projecting portion 11 is here of prismatic shape, with the opposing surfaces 14 and 15, and end surfaces 16 and 17 on the short sides of the envelope rectangle of the profile 12, which are all flat, in a particular embodiment.
  • the figure 3 illustrates an optimized alternative geometry, derived from that of the figure 2 .
  • the longest support parts, the main projection 11, but also the other parts 11A, 11B are cut and include cutouts 18, especially in the form of slots, to induce a partial self-demagnetization in absence of the external field.
  • These cuts 18 extend in a direction parallel to the main axis DP.
  • the longest parts, used as support have an important aspect ratio, the largest dimension being oriented with its main axis DP in the direction orthogonal to the direction of preferential magnetization DA of the environment of the movement .
  • the depth of the cuts 18 is greater than or equal to half the length of the portion 11 or 11A considered exceeding the average radius of the cylindrical portion of the shaft 1.
  • the shaft 1 according to the invention is symmetrical with respect to a plane passing through the pivot axis D and parallel to the direction of the main axis DP.
  • the surfaces of revolution 19, including the pivots and the cylindrical body of the balance shaft may be identical to the pivots and the cylindrical body of a traditional balance shaft: the mechanical performance of the component are therefore unaltered compared to the balance shafts existing.
  • the shafts shown in the figures have a preferred direction of magnetization parallel to the main axis DP and chosen so as to be orthogonal to the direction of preferential magnetization DA of the environment of the movement (when the balance spring is at rest ).
  • the remanent field will be oriented preferably like the external field while the remanent field created in the environment of the movement will be oriented according to the orientation of the fixed ferromagnetic components (bars, screws, bridges), according to the direction of preferential magnetization DA.
  • a residual magnetic torque acts on the balance shaft as on a compass needle.
  • the residual effect for a geometrically optimized shaft 1 according to the invention is different from that observed for a traditional tree.
  • the main axis DP of the shaft 1 is orthogonal to the preferred direction of magnetization DAP of the environment, for almost all possible orientations of the external field (except the orientation in the preferred direction of magnetization DAP of the environment) the resulting residual magnetic torque on the shaft1 is an even function of the oscillation angle, which makes the residual run fault almost null.
  • the shaft is magnetized in the same direction, thus orthogonal to the main axis DP, but in this case its magnetization is low, less than 0.2 T, as shown in figure 4 which illustrates the distribution of the remanent field, after magnetization at 0.2 T in the direction orthogonal to the main axis DP, of an optimized steel pendulum shaft 1 AP.
  • the magnetic torque is, in this case, an odd function of the oscillation angle, but it is between 10 and 100 times (depending on the geometry) lower than the torque acting on a traditional tree, as visible on the figure 5 , which illustrates, in the form of a graph, the comparison of the magnetic pairs exerted on a traditional balance shaft according to the graph GT shown in broken lines, and on a tree 1 optimized according to the invention according to the graph GO is shown in a line continued.
  • On the abscissa is the angle in degrees, and in ordinate the torque exerted on the balance, in mN.mm.
  • the residual run error is then reduced by a factor between 3 and 10.
  • the material of the shaft 1 is magnetically homogeneous in the simple embodiment illustrated by the figures. This particular embodiment does not exclude the embodiments where the shaft 1 is magnetically inhomogeneous.
  • the invention thus makes it possible to modify the geometry of the balance shaft (and not the whole balance), because the shaft is generally the only magnetic component, which is difficult to replace with a non-magnetic material. And it is the influence of the tree itself that must be reduced, this goal is achieved by the invention.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Micromachines (AREA)
  • Hard Magnetic Materials (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Metallurgy (AREA)
  • Soft Magnetic Materials (AREA)
  • Electromechanical Clocks (AREA)
  • Electric Clocks (AREA)
  • Magnetic Treatment Devices (AREA)

Description

Domaine de l'inventionField of the invention

L'invention concerne un mécanisme comportant un mobile, comportant un arbre, destiné à pivoter autour d'un axe de pivotement et comportant au moins une partie saillante de plus grand rayon autour dudit axe de pivotement, ledit arbre étant en acier, ledit mobile oscillant autour d'une position de repos définie par un plan de repos passant par ledit axe de pivotement, ledit mobile étant rappelé vers ladite position de repos par des moyens de rappel élastique, ledit mécanisme ayant une direction d'aimantation préférentielle.The invention relates to a mechanism comprising a mobile, comprising a shaft, intended to pivot about a pivot axis and comprising at least one projecting part of greater radius about said pivot axis, said shaft being made of steel, said oscillating mobile around a rest position defined by a rest plane passing through said pivot axis, said mobile being biased towards said rest position by elastic return means, said mechanism having a preferred direction of magnetization.

L'invention concerne encore un mouvement d'horlogerie comportant au moins un tel mécanisme.The invention also relates to a watch movement comprising at least one such mechanism.

L'invention concerne encore une montre comportant au moins un tel mouvement d'horlogerie, ou/et comportant au moins un tel mécanisme.The invention also relates to a watch comprising at least one such watch movement, and / or comprising at least one such mechanism.

L'invention concerne le domaine des mécanismes d'horlogerie, en particulier le domaine des organes réglants, en particulier pour des montres mécaniques.The invention relates to the field of watch mechanisms, in particular the field of regulating members, in particular for mechanical watches.

Arrière-plan de l'inventionBackground of the invention

L'organe réglant d'une montre mécanique est constitué par un oscillateur harmonique, le balancier-spiral, dont la fréquence propre d'oscillation dépend principalement de l'inertie du balancier et de la rigidité élastique du spiral.The regulating organ of a mechanical watch is constituted by a harmonic oscillator, the sprung balance, whose oscillation natural frequency depends mainly on the inertia of the balance and the elastic rigidity of the spiral.

Les oscillations du balancier-spiral, autrement amorties, sont entretenues par les impulsions fournies par un échappement généralement composé par un ou deux mobiles pivotants. Dans le cas de l'échappement à ancre suisse, ces mobiles pivotants sont l'ancre et la roue d'échappement. La marche de la montre est déterminée par la fréquence du balancier-spiral et par la perturbation générée par l'impulsion de l'échappement, qui généralement ralentit l'oscillation propre du balancier-spiral et donc provoque un retard de marche.The oscillations of the sprung balance, otherwise damped, are maintained by the pulses provided by an escapement generally composed of one or two pivoting mobiles. In the case of the Swiss lever escapement, these pivoting mobiles are the anchor and the escape wheel. The march of the watch is determined by the frequency of the sprung balance and by the disturbance generated by the impulse of the escapement, which generally slows down the natural oscillation of the sprung balance and thus causes a delay in running.

La marche de la montre est donc perturbée par tous les phénomènes qui peuvent altérer la fréquence propre du balancier-spiral et/ou la dépendance temporelle de l'impulsion fournie par l'échappement.The march of the watch is therefore disturbed by all the phenomena that can alter the natural frequency of the sprung balance and / or the time dependence of the impulse provided by the escapement.

En particulier, suite à l'exposition transitoire d'une montre mécanique à un champ magnétique, des défauts de marche (liés à l'effet résiduel du champ) sont généralement observés. L'origine de ces défauts est la magnétisation permanente des composants ferromagnétiques fixes du mouvement ou de l'habillage et la magnétisation permanente ou transitoire des composants magnétiques mobiles faisant partie de l'organe réglant (balancier-spiral) et/ou de l'échappement.In particular, following the transient exposure of a mechanical watch to a magnetic field, gait defects (related to the residual effect of the field) are generally observed. The origin of these defects is permanent magnetization fixed ferromagnetic components of the movement or the covering and the permanent or transient magnetization of the moving magnetic components forming part of the regulating member (balance spring) and / or the escapement.

Après l'exposition au champ, les composants mobiles (balancier, spiral, échappement) magnétisés ou perméables magnétiquement sont soumis à un couple magnétostatique et/ou à des forces magnétostatiques. En principe, ces interactions modifient la rigidité apparente du balancier-spiral, la dynamique des mobiles d'échappement et les frottements. Ces modifications produisent un défaut de marche qui peut aller de quelques dizaines à quelques centaines de secondes par jour.After exposure to the field, magnetically or magnetically permeable mobile components (balance, hairspring, exhaust) are subjected to magnetostatic torque and / or magnetostatic forces. In principle, these interactions modify the apparent rigidity of the sprung balance, the dynamics of the escape mobiles and the friction. These modifications produce a fault that can range from a few tens to a few hundred seconds a day.

L'interaction du mouvement horloger avec le champ externe, lors de l'exposition, peut aussi mener à l'arrêt du mouvement. En principe, l'arrêt sous champ et le défaut de marche résiduel ne sont pas corrélés, parce que l'arrêt sous champ dépend de l'aimantation transitoire, sous-champ, des composants (et donc de la perméabilité et du champ de saturation des composants), tandis que le défaut de marche résiduel dépend de l'aimantation résiduelle (et donc, principalement, du champ coercitif des composants) qui peut être faible même en présence d'une perméabilité magnétique importante.The interaction of the watch movement with the external field, during the exhibition, can also lead to the stop of the movement. In principle, the arrest in the field and the residual run-out are not correlated, because the arrest in field depends on the transient magnetization, sub-field, of the components (and therefore of the permeability and the saturation field). components), while the residual run fault depends on the residual magnetization (and therefore, mainly, the coercive field of the components) which can be low even in the presence of a significant magnetic permeability.

Après l'introduction des spiraux fabriqués en matériaux très faiblement paramagnétiques (par exemple, en silicium), le spiral n'est plus responsable du défaut de marche des montres. Les perturbations magnétiques encore observables pour des champs d'aimantation inférieurs à 1,5 Tesla sont donc dues à l'aimantation de l'arbre de balancier et à l'aimantation des mobiles d'échappement.After the introduction of spirals made of very weakly paramagnetic materials (for example, silicon), the spiral is no longer responsible for the lack of running watches. The magnetic disturbances still observable for magnetization fields below 1.5 Tesla are therefore due to the magnetization of the balance shaft and to the magnetization of the escapement wheels.

Le corps d'ancre et la roue d'échappement peuvent être fabriqués en matériaux très faiblement paramagnétiques, sans que leur performance mécanique en soit affectée. Au contraire, les arbres des mobiles nécessitent de très bonnes performances mécaniques (bonne tribologie, faible fatigue) pour permettre un pivotement optimal et constant dans le temps, et il est donc préférable de les fabriquer en acier trempable (typiquement en acier au carbone de type 20AP ou similaire). Or de tels aciers sont des matériaux sensibles aux champs magnétiques parce qu'ils présentent un champ de saturation élevé combiné à un champ coercitif élevé. Les arbres de balancier, ancre et roue d'échappement sont actuellement les composants les plus critiques face aux perturbations magnétiques de la montre.The anchor body and the escape wheel can be made of very low paramagnetic materials, without their mechanical performance being affected. On the contrary, the shafts of the mobiles require very good mechanical performances (good tribology, low fatigue) to allow an optimal and constant pivoting in the time, and it is therefore preferable to manufacture them in hardened steel (typically carbon steel type 20AP or the like). However, such steels are materials sensitive to magnetic fields because they have a high saturation field combined with a high coercive field. The balance, anchor and escape wheel shafts are currently the most critical components in the face of the magnetic disturbances of the watch.

En particulier, l'arbre de balancier est le composant le plus sensible pour la chronométrie (effet résiduel), parce qu'un couple perturbateur d'origine magnétique agissant sur l'arbre modifie directement la fréquence d'oscillation du balancier-spiral, et cette modification est, en principe, illimitée (elle dépend uniquement de l'intensité des champs magnétiques résiduels et de la rigidité du spiral), tandis qu'une perturbation de la fonction d'échappement donne un défaut de marche limité par le retard à l'échappement nominal (la perturbation résultante ne peut pas être beaucoup plus importante que la perturbation déjà produite par l'échappement en conditions normales).In particular, the balance shaft is the most sensitive component for chronometry (residual effect), because a disturbing torque of magnetic origin acting on the shaft directly modifies the oscillation frequency of the balance-spring, and this modification is, in principle, unlimited (it depends solely on the intensity of the residual magnetic fields and the rigidity of the hairspring), while a disturbance of the exhaust function gives a defect limited by the delay nominal exhaust (the resulting disturbance can not be much larger than the disturbance already produced by the exhaust under normal conditions).

Le document FR 2 275 815 A1 NIVAROX décrit la fabrication d'un axe de balancier à partir d'un profilé comportant plusieurs ailes réparties autour de l'axe de pivotement., et une variante avec deux ailes curvilignes.The document FR 2 275 815 A1 NIVAROX describes the manufacture of a balance shaft from a profile with several wings distributed around the pivot axis., And a variant with two curvilinear wings.

Le document FR 2 090 784 A5 FEINMETALL décrit l'assemblage d'un spiral à un balancier comportant une traverse avec deux ailes sensiblement symétriques.The document FR 2 090 784 A5 FEINMETALL describes the assembly of a spiral to a balance having a crossbar with two substantially symmetrical wings.

Le document JP S62 63884 A ZENKOSHA TOKEI décrit l'usinage par taillage d'un balancier comportant deux ailes.The document JP S62 63884 A ZENKOSHA TOKEI describes the machining by cutting a balance with two wings.

Le document WO 01/77759 A1 DETRA décrit un dispositif d'échappement comprenant un rouage de transmission d'énergie vers un oscillateur apte à recevoir cette énergie et à transmettre une fréquence d'oscillation, et des premiers moyens aptes à produire au moins une première portion de l'énergie transmise par ce rouage et destinée à alimenter l'oscillateur, où les premiers moyens sont configurés de manière à fournir un couple mécanique essentiellement variable en fonction de l'angle de déplacement angulaire du rouage, ce couple mécanique présentant au moins une position stable, et au moins une position instable, sur une période de déplacement angulaire du rouage. Dans une réalisation particulière, ces premiers moyens produisent un couple magnétique variable en fonction du temps, par la combinaison d'un rotor aimanté diamétralement, avec un stator comportant des alvéoles au niveau de son alésage recevant ce rotor.The document WO 01/77759 A1 DETRA describes an escapement device comprising a gear train for transmitting energy to an oscillator capable of receiving this energy and transmitting an oscillation frequency, and first means capable of producing at least a first portion of the energy transmitted by this gear train and intended to feed the oscillator, where the first means are configured so as to provide a substantially variable mechanical torque as a function of the angular displacement angle of the gear train, this mechanical torque having at least one stable position, and at least one an unstable position, over a period of angular displacement of the gear train. In a particular embodiment, these first means produce a variable magnetic torque as a function of time, by the combination of a magnetized rotor diametrically, with a stator having cells at its bore receiving this rotor.

Résumé de l'inventionSummary of the invention

L'invention se propose de limiter l'interaction magnétique sur un arbre de mobile, en particulier sur un arbre de balancier.The invention proposes to limit the magnetic interaction on a mobile shaft, in particular on a balance shaft.

A cet effet, l'invention concerne un mécanisme selon la revendication 1.For this purpose, the invention relates to a mechanism according to claim 1.

Selon une caractéristique de l'invention, ledit mécanisme est un mécanisme d'échappement, et ledit mobile est un balancier ramené vers ladite position de repos par au moins un ressort-spiral, et ledit arbre est un arbre de balancier.According to a feature of the invention, said mechanism is an escape mechanism, and said mobile is a pendulum brought to said rest position by at least one spiral spring, and said shaft is a balance shaft.

L'invention concerne encore un mouvement d'horlogerie comportant au moins un tel mécanisme.The invention also relates to a watch movement comprising at least one such mechanism.

L'invention concerne encore une montre comportant au moins un tel mouvement d'horlogerie, ou/et comportant au moins un tel mécanisme.The invention also relates to a watch comprising at least one such watch movement, and / or comprising at least one such mechanism.

Description sommaire des dessinsBrief description of the drawings

D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la-description détaillée qui va suivre, en référence aux dessins annexés, où :

  • la figure 1 représente, sous forme d'un schéma tridimensionnel, une première variante d'arbre de mobile comportant des usinages de révolution autour d'un axe de pivotement, dont une partie saillante de plus grand encombrement radial que les autres, cet arbre comportant deux surfaces latérales symétriques par rapport à cet axe de pivotement, et à une distance l'une de l'autre telle que le rapport de forme de cette partie saillante, en projection selon un plan perpendiculaire à l'axe de pivotement, est supérieur à 2, et où la plus grande dimension, dite « axe principal » s'étend de façon orthogonale à une direction d'aimantation préférentielle de l'environnement immédiat du mobile ;
  • la figure 2 représente, de façon similaire à la figure 1, une deuxième variante d'arbre de mobile où la partie saillante est de profil rectangulaire avec un rapport de forme supérieur à 2, et où certaines parties constituant des support d'autres composants sont également de profil rectangulaire ;
  • la figure 3 représente une variante de la figure 2, où la partie saillante et une autre partie de profil rectangulaire comportent des découpes s'étendant selon leur plus grand dimension ;
  • la figure 4 représente, de façon schématisée, en vue de bout selon la direction de l'axe principal de l'arbre de la figure 2, et avec une coloration grisée d'autant plus intense que le champ rémanent est élevé, après son exposition à un champ magnétique selon la direction d'aimantation préférentielle de l'environnement du mobile;
  • la figure 5 illustre, sous forme d'un graphe, la comparaison des couples magnétiques exercés sur un arbre de balancier traditionnel selon le graphe GT représenté en trait interrompu, et sur un arbre optimisé selon l'invention selon le graphe GO est représenté en trait continu. En abscisse figure l'angle en degrés, et en ordonnée le couple exercé sur le balancier, en mN.mm ;
  • la figure 6 est une vue de bout, selon la direction de l'axe de pivotement, d'un arbre selon la figure 1, et illustré comme la transformation d'un arbre entièrement de révolution et de plus grand rayon RMAX;
  • la figure 7 représente, sous forme d'un schéma-blocs, une pièce d'horlogerie, comportant un mouvement comportant un mécanisme comportant un mobile équipé d'un arbre selon l'invention.
Other features and advantages of the invention will appear on reading the following detailed description, with reference to the appended drawings, in which:
  • the figure 1 represents, in the form of a three-dimensional diagram, a first variant of a mobile shaft comprising machining of revolution about a pivot axis, including a protruding part of larger radial size than the others, this shaft having two lateral surfaces symmetrical with respect to this pivot axis, and at a distance from one another such that the aspect ratio of this projecting portion, in projection along a plane perpendicular to the pivot axis, is greater than 2, and where the largest dimension, called the "main axis" extends orthogonally to a direction of preferential magnetization of the immediate environment of the mobile;
  • the figure 2 represents, similarly to the figure 1 a second variant of a mobile shaft in which the projecting portion is of rectangular profile with a shape ratio greater than 2, and where certain parts constituting supports for other components are also of rectangular profile;
  • the figure 3 represents a variant of the figure 2 wherein the protruding portion and another rectangular profile portion have cutouts extending along their largest dimension;
  • the figure 4 represents, schematically, end view in the direction of the main axis of the tree of the figure 2 , and with a gray color all the more intense as the remnant field is high, after being exposed to a magnetic field according to the direction of preferential magnetization of the mobile environment;
  • the figure 5 illustrates, in the form of a graph, the comparison of the magnetic couples exerted on a traditional balance shaft according to the graph GT shown in broken lines, and on an optimized shaft according to the invention according to the graph GO is shown in solid lines. On the abscissa is the angle in degrees, and in ordinate the torque exerted on the balance, in mN.mm;
  • the figure 6 is an end view, in the direction of the pivot axis, of a tree according to the figure 1 , and illustrated as the transformation of a tree completely of revolution and larger radius RMAX;
  • the figure 7 represents, in the form of a block diagram, a timepiece, comprising a movement comprising a mechanism comprising a mobile equipped with a shaft according to the invention.

Description détaillée des modes de réalisation préférésDetailed Description of the Preferred Embodiments

L'invention plus particulièrement le domaine des organes réglants d'horlogerie pour des montres mécaniques.The invention more particularly the field of clocking devices for mechanical watches.

L'invention se propose de limiter l'interaction magnétique sur un arbre de mobile, en particulier sur un arbre de balancier.The invention proposes to limit the magnetic interaction on a mobile shaft, in particular on a balance shaft.

L'invention concerne ainsi un arbre de mobile à géométrie optimisée en environnement magnétique.The invention thus relates to a mobile shaft with optimized geometry in a magnetic environment.

L'invention peut permettre à des montres avec spiral, corps d'ancre et roue d'échappement amagnétiques de résister, sans s'arrêter, à des champs magnétiques d'intensité élevée, de l'ordre de 0,5 Tesla, sans que les performances mécaniques (chronométrie et vieillissement des mobiles) soient affectées.The invention can allow watches with spiral, anchor body and nonmagnetic escape wheel to resist, without stopping, magnetic fields of high intensity, of the order of 0.5 Tesla, without the mechanical performances (chronometry and aging of the mobiles) are affected.

La mise en oeuvre de l'invention permet de réduire l'effet résiduel des montres avec spiral, corps d'ancre et roue d'échappement amagnétiques à moins de une seconde par jour.The implementation of the invention makes it possible to reduce the residual effect of watches with spiral, anchor body and non-magnetic escape wheel to less than one second per day.

Par convention, on appelle, dans la présente description « axe » un élément géométrique virtuel tel qu'un axe de pivotement, et « arbre » un élément mécanique réel, réalisé en une ou plusieurs parties. Par exemple, une paire de pivots 2A et 2B alignés et rapportés de part et d'autre d'une partie médiane 6 d'un mobile 10, pour le guider en pivotement est aussi dénommée « arbre ».By convention, the term "axis" refers to a virtual geometric element such as a pivot axis, and "shaft" to a real mechanical element, made in one or more parts. For example, a pair of pivots 2A and 2B aligned and reported on either side of a median portion 6 of a mobile 10, to guide it in pivoting is also called "tree".

Dans la suite de l'exposé, on définit par matériaux « perméables magnétiquement », des matériaux qui ont une perméabilité relative comprise entre 10 et 10000, comme des aciers, qui ont une perméabilité relative voisine de 100 pour des arbres de balanciers par exemple, ou voisine de 4000 pour les aciers utilisés couramment dans les circuits électriques, ou encore d'autres alliages dont la perméabilité relative atteint des valeurs de 8000 à 10000.In the remainder of the discussion, "magnetically permeable" materials are defined as materials having a relative permeability that is between 10 and 10,000, such as steels, which have a relative permeability close to 100 for balance shafts for example, or close to 4000 for steels commonly used in electrical circuits, or other alloys whose relative permeability reaches values from 8000 to 10000.

On appellera matériaux « magnétiques », par exemple dans le cas de masses polaires, des matériaux aptes à être aimantés de façon à présenter un champ rémanent compris entre 0,1 et 1,5 Tesla, comme par exemple le « Neodymium Iron Boron » d'une densité d'énergie magnétique Em voisine de 512 kJ/m3 et donnant un champ rémanent de 0,5 à 1,3 Tesla. Un niveau de champ rémanent inférieur, vers la partie inférieure de la fourchette peut être utilisé en cas de combinaison, dans un couple d'aimantation, d'un tel matériau magnétique avec un composant antagoniste perméable magnétiquement de perméabilité élevée, plus proche de 10000, dans la fourchette de 100 à 10000."Magnetic" materials, for example in the case of polar masses, will be called materials capable of being magnetized so as to have a residual field of between 0.1 and 1.5 Tesla, such as for example the "Neodymium Iron Boron". a magnetic energy density Em close to 512 kJ / m 3 and giving a residual field of 0.5 to 1.3 Tesla. A lower residual field level, towards the lower part of the range can be used when combining, in a magnetization couple, such a magnetic material with a magnetically permeable antagonist component of high permeability, closer to 10000, in the range of 100 to 10,000.

On appellera matériaux « ferromagnétiques » des matériaux dont les caractéristiques sont : champ de saturation Bs > 0 à la température T = 23°C, champ coercitif Hc > 0 à la température T = 23°C, perméabilité magnétique maximale µR > 2 à la température T = 23°C, température de Curie Tc > 60°C.Ferromagnetic materials are materials whose characteristics are: saturation field Bs> 0 at temperature T = 23 ° C, coercive field Hc> 0 at temperature T = 23 ° C, maximum magnetic permeability μ R > 2 at the temperature T = 23 ° C, Curie temperature Tc> 60 ° C.

Plus particulièrement, on qualifiera de « faiblement ferromagnétiques » ceux dont les caractéristiques sont : champ de saturation Bs < 0,5 T à la température T = 23°C, champ coercitif Hc < 1'000 kA/m à la température T = 23°C, perméabilité magnétique maximale µR < 10 à la température T = 23°C, température de Curie Tc > 60°C.More particularly, those whose characteristics are: saturation field Bs <0.5 T at temperature T = 23 ° C, coercive field Hc <1000 kA / m at temperature T = 23, will be described as "weakly ferromagnetic". ° C, maximum magnetic permeability μ R <10 at temperature T = 23 ° C, Curie temperature Tc> 60 ° C.

Plus particulièrement, on qualifiera de « fortement ferromagnétiques » ceux dont les caractéristiques sont : champ de saturation Bs > 1 T à la température T = 23°C, champ coercitif Hc > 3'000 kA/m à la température T = 23°C, perméabilité magnétique maximale µR > 50 à la température T = 23°C, température de Curie Tc > 60°C.More particularly, those whose characteristics are: saturation field Bs> 1 T at temperature T = 23 ° C, coercive field Hc> 3,000 kA / m at temperature T = 23 ° C, will be described as "strongly ferromagnetic". , maximum magnetic permeability μ R > 50 at temperature T = 23 ° C, Curie temperature Tc> 60 ° C.

On appellera matériaux « paramagnétiques » des matériaux de perméabilité magnétique relative comprise entre 1,0001 et 100, par exemple pour des entretoises interposées entre un matériau magnétique et un composant antagoniste perméable magnétiquement, ou encore entre deux matériaux magnétiques, par exemple une entretoise entre un composant et une masse polaire. Par exemple, des matériaux faiblement paramagnétiques sont : aluminium, or, laiton ou similaire (perméabilité magnétique inférieure à 2)."Paramagnetic" materials will be referred to as materials having a relative magnetic permeability of between 1.0001 and 100, for example for spacers interposed between a magnetic material and a magnetically permeable antagonist component, or alternatively between two magnetic materials, for example a spacer between a component and a polar mass. For example, weakly paramagnetic materials are: aluminum, gold, brass or the like (magnetic permeability less than 2).

On appellera matériaux «diamagnétiques » des matériaux de perméabilité magnétique relative inférieure à 1 (susceptibilité magnétique négative, inférieure ou égale à -10-5), tels que graphite ou graphène."Diamagnetic" materials will be referred to as materials of relative magnetic permeability less than 1 (negative magnetic susceptibility, less than or equal to -10 -5 ), such as graphite or graphene.

On appellera enfin matériaux «magnétiques doux», pour ne pas dire amagnétiques, notamment pour des blindages, des matériaux ayant une perméabilité élevée mais une haute saturation, car on ne veut pas qu'ils soient aimantés de manière permanente: ils doivent conduire le mieux possible le champ, de manière à réduire le champ à leur extérieur. De tels composants peuvent alors protéger aussi un système magnétique des champs externes. Ces matériaux sont choisis de préférence de perméabilité magnétique relative comprise entre 50 et 200, et avec un champ de saturation supérieur à 500 A/m.Finally, we will call "soft magnetic" materials, not to say non-magnetic, especially for shielding, materials with high permeability but high saturation, because we do not want them to be permanently magnetized: they must drive the best possible the field, so as to reduce the field to their outside. Such components can then also protect a magnetic system from external fields. These materials are preferably chosen to have a relative magnetic permeability of between 50 and 200, and with a saturation field greater than 500 A / m.

Des matériaux qualifiés d'«amagnétiques », ont quant à eux une perméabilité magnétique relative très légèrement supérieure à 1, et inférieure à 1,0001, comme typiquement le silicium, le diamant, le palladium et similaires. Ces matériaux peuvent en général être obtenus par des technologies MEMS ou par le procédé « LIGA ».Materials described as "non-magnetic" have a relative magnetic permeability very slightly greater than 1, and less than 1.0001, as typically silicon, diamond, palladium and the like. These materials can generally be obtained by MEMS technologies or by the "LIGA" process.

L'invention concerne un arbre 1 d'horlogerie, pour un mobile 10, et optimisé pour le fonctionnement de ce mobile 10 dans un environnement où règne un champ magnétique résiduel selon une direction d'aimantation préférentielle DAP.The invention relates to a watchmaking tree 1, for a mobile 10, and optimized for the operation of this mobile 10 in an environment where there is a residual magnetic field in a preferred direction of magnetization DAP.

Dans une réalisation préférée et décrite ci-après en détail et illustrée par les figures, ce mobile 10 est un balancier. L'homme du métier saura extrapoler l'invention à d'autres mobiles horlogers pour lesquels il souhaite se soustraire à l'influence d'un champ magnétique résiduel.In a preferred embodiment and described hereinafter in detail and illustrated by the figures, this mobile 10 is a pendulum. The person skilled in the art will be able to extrapolate the invention to other watchmobiles for which he wishes to avoid the influence of a residual magnetic field.

La géométrie d'un arbre 1 de balancier 10 usuel, relativement standard dans l'industrie horlogère, n'est pas optimisée pour limiter son aimantation sous un champ externe. En fait, la partie médiane 6 de l'arbre 1, ayant un plus grand rayon RMAX, est fortement aimantée par un champ magnétique orthogonal ou oblique par rapport à la direction de l'axe de pivotement D. A cause de cette aimantation, en présence d'un champ environnemental (champ externe ou créé par les composants magnétisés du mouvement ou de la montre), l'arbre 1 est soumis à un couple magnétique important.The geometry of a standard balance shaft 1, relatively standard in the watch industry, is not optimized to limit its magnetization under an external field. In fact, the median part 6 of the shaft 1, having a larger radius RMAX, is strongly magnetized by a magnetic field orthogonal or oblique with respect to the direction of the pivot axis D. Because of this magnetization, in presence of an environmental field (external field or created by the magnetized components of the movement or the watch), the shaft 1 is subjected to a large magnetic torque.

Le balancier 10 fait partie d'un mécanisme d'échappement 20, dans un mouvement 30 d'une montre 40.The rocker 10 is part of an escapement mechanism 20, in a movement 30 of a watch 40.

L'invention se propose de modifier la géométrie de l'arbre 1 de balancier, en modifiant le rapport de forme de la partie dite saillante 11, qui est la partie de plus grand encombrement radial de cet arbre de balancier, en lui donnant, en projection sur un plan perpendiculaire à l'axe de pivotement D de l'arbre 1 du balancier 10, un rapport de forme très différent de 1, de préférence supérieur ou égal à 2.The invention proposes to modify the geometry of the balance shaft 1, by modifying the aspect ratio of the so-called projecting part 11, which is the part of larger radial size of this balance shaft, by giving it, in projection on a plane perpendicular to the pivot axis D of the shaft 1 of the balance 10, a form ratio very different from 1, preferably greater than or equal to 2.

L'idée est de réduire une des deux dimensions x ou y (en projection dans un plan perpendiculaire à l'axe de pivotement D), la manière la plus simple est de limiter localement l'arbre 1 par deux surfaces 14, 15, sensiblement parallèles à l'axe D, lesquelles surfaces 14 et 15 sont de préférence deux plans parallèles à l'axe D ; en effet, si les surfaces, notamment les plans, ne sont pas parallèles, il reste alors une partie plus large qui peut s'aimanter davantage que le reste. Ces deux surfaces 14 et 15 sont de préférence très proches l'une de l'autre, pour réduire l'aimantation dans cette direction, et pour bien définir une seule direction privilégiée d'aimantation dans le plan xy.The idea is to reduce one of the two dimensions x or y (in projection in a plane perpendicular to the pivot axis D), the simplest way is to locally limit the shaft 1 by two surfaces 14, 15, substantially parallel to the axis D, which surfaces 14 and 15 are preferably two planes parallel to the axis D; indeed, if the surfaces, especially the planes, are not parallel, then there remains a larger part which can be magnetized more than the rest. These two surfaces 14 and 15 are preferably very close to each other, to reduce the magnetization in this direction, and to well define a single preferred direction of magnetization in the xy plane.

La projection de cette partie saillante 11 selon un plan perpendiculaire à l'axe de pivotement D du balancier 10, a un profil 12, qui s'inscrit dans un rectangle R symétrique par rapport à deux axes orthogonaux, dont un axe principal DP selon lequel s'étend la plus grande dimension de cette partie saillante 11. Le rapport de forme est le rapport entre les deux dimensions du rectangle, longueur LR et largeur LA.The projection of this projecting portion 11 along a plane perpendicular to the pivot axis D of the balance 10, has a profile 12, which is inscribed in a rectangle R symmetrical with respect to two orthogonal axes, of which a principal axis DP according to which extends the largest dimension of this protruding portion 11. The aspect ratio is the ratio between the two dimensions of the rectangle, length LR and width LA.

De ce fait, après transformation, l'arbre 1 de balancier n'a plus de symétrie de révolution.As a result, after transformation, the balance shaft 1 has no revolution symmetry.

Selon l'invention, en position de repos du balancier, cet axe principal DP, selon lequel s'étend la plus grande dimension de cette partie saillante 11 se trouve en position orthogonale par rapport à la direction d'aimantation préférentielle DA de l'environnement du mouvement. Cet axe principal DA est généralement déterminée par des ponts, des barrettes, des vis, ou similaires ; elle dépend directement de la construction et généralement elle est assez évidente, par l'examen du facteur de forme des composants en acier près de l'axe ; dans des situations ambiguës, il suffit de réaliser une simulation par éléments fini ou par charges équivalentes pour la déterminer facilement.According to the invention, in the rest position of the balance, this main axis DP, which extends the largest dimension of this projecting portion 11 is in the orthogonal position relative to the direction of preferential magnetization DA of the environment some movement. This main axis DA is generally determined by bridges, bars, screws, or the like; it depends directly on the construction and generally it is quite obvious, by the examination of the form factor of the steel components near the axis; in ambiguous situations, it is sufficient to perform a finite element simulation or equivalent loads to determine it easily.

Cette position dite « de repos » du balancier correspond à celle qu'il occupe quand le spiral est au repos : c'est la position dans laquelle le mouvement est le moins souvent, mais, comme expliqué dans la suite de l'exposé, c'est la position moyenne et, pour les champs externes très intenses, c'est la position qui définit l'aimantation résultante.This so-called "rest" position of the balance corresponds to that it occupies when the hairspring is at rest: this is the position in which the movement is the least often, but, as explained in the rest of the presentation, is the position medium and, for very strong external fields, it is the position that defines the resulting magnetization.

Dans une réalisation particulière, le plateau du balancier a sa plus grande dimension perpendiculaire à la ligne d'échappement, ce qui permet de maximiser les effets de surface face aux effets de volume, de manière à réduire au minimum l'aimantation dans la direction du champ et, partant, les effets « boussole » qui créent un couple perturbateur.In a particular embodiment, the balance plate has its largest dimension perpendicular to the exhaust line, which makes it possible to maximize the surface effects in the face of the volume effects, so as to minimize magnetization in the direction of rotation. field and, hence, the "compass" effects that create a disruptive couple.

La combinaison de la fabrication de l'arbre 1 selon un tel profil 12, avec l'orientation orthogonale de son axe principal DP par rapport à la direction d'aimantation préférentielle DA, est appelée « géométrie magnétiquement optimisée ».The combination of the manufacture of the shaft 1 according to such a profile 12, with the orthogonal orientation of its main axis DP relative to the direction of preferential magnetization DA, is called "magnetically optimized geometry".

Plusieurs variantes sont illustrées par les figures.Several variants are illustrated by the figures.

La figure 1 montre un arbre 1 de balancier avec une géométrie magnétiquement optimisée réaliste. Les parties les plus larges, qui sont utilisées comme support, ont un rapport de forme important, la dimension la plus grande étant orientée avec son axe principal DP dans la direction orthogonale à la direction d'aimantation préférentielle DA de l'environnement du mouvement. Cet arbre 1 est dessiné sur une base classique d'arbre de balancier, avec des portées tournées de pivots, de supports: d'appui de virole, de serge, d'assiette, de double plateau, ou autres. Sur cet exemple, la partie de plus grand diamètre 11 sert d'appui à une face d'une serge 50, non représentée sur la figure, l'arbre 1 comportant une portée 13 de centrage de cette serge; le profil 12 est ici réalisé par usinage, notamment par fraisage ou tournage, ou similaire, de deux surfaces antagonistes 14 et 15, tel que visible aussi sur la figure 6, ces surfaces sont des surfaces planes dans une exécution simplifiée et préférée. Cette variante permet de transformer à peu de frais des arbres de balanciers existants pour les adapter à l'invention, les autres composants du balancier, ou du mécanisme dans lequel il est intégré, ne nécessitant aucune modification géométrique.The figure 1 shows a pendulum shaft 1 with a magnetically optimized realistic geometry. The widest portions, which are used as a support, have an important aspect ratio, the largest dimension being oriented with its main axis DP in the direction orthogonal to the direction of preferential magnetization DA of the environment of the movement. This tree 1 is drawn on a conventional balance-shaft base, with spans turned pivots, supports: ferrule support, serge, plate, double tray, or others. In this example, the portion of larger diameter 11 serves to support a face of a serge 50, not shown in the figure, the shaft 1 having a bearing surface 13 of this serge; the profile 12 is here produced by machining, in particular by milling or turning, or the like, of two opposing surfaces 14 and 15, as also visible on the figure 6 these surfaces are planar surfaces in a simplified and preferred embodiment. This variant makes it possible to convert inexpensively existing rocker shafts to adapt them to the invention, the other components of the balance, or the mechanism in which it is integrated, requiring no geometric modification.

La figure 2 montre un arbre 1 de balancier avec une géométrie magnétiquement optimisée schématisée. Les parties les plus larges, qui sont utilisées comme support, ont un rapport de forme important, la dimension la plus grande étant orientée avec son axe principal DP dans la direction orthogonale à la direction d'aimantation préférentielle DA de l'environnement du mouvement. Si certaines portées, notamment les pivots, restent de révolution, la partie saillante 11 est ici de forme prismatique, avec les surfaces antagonistes 14 et 15, et des surfaces de bout 16 et 17 sur les petits côtés du rectangle enveloppe du profil 12, qui sont toutes planes, dans une réalisation particulière. Pour d'autres fonctions d'appui de l'arbre 1 de balancier, d'autres parties 11A, 11B, avec un rapport de forme supérieur à 1 sont ménagées parallèlement à la partie saillante principale 11, et ont toutes leur axe principal DP dans la direction orthogonale à la direction d'aimantation préférentielle DA. Le fraisage en bout des faces 16A, 16B, 17A, 17B, conjugué avec le fraisage des prolongements des plans 14 et 15 au niveau de ecs parties 11A, 11B, offre l'avantage de permettre la fuite des champs magnétiques, et de réduire davantage l'aimantation résiduelle.The figure 2 shows a balance shaft 1 with magnetically optimized geometry schematized. The widest portions, which are used as a support, have an important aspect ratio, the largest dimension being oriented with its main axis DP in the direction orthogonal to the direction of preferential magnetization DA of the environment of the movement. If certain spans, including the pivots, remain of revolution, the projecting portion 11 is here of prismatic shape, with the opposing surfaces 14 and 15, and end surfaces 16 and 17 on the short sides of the envelope rectangle of the profile 12, which are all flat, in a particular embodiment. For other support functions of the balance shaft 1, other parts 11A, 11B, with a shape ratio greater than 1 are formed parallel to the main projection 11, and all have their main axis DP in the direction orthogonal to the direction of preferential magnetization DA. The end milling of the faces 16A, 16B, 17A, 17B, combined with the milling of the extensions of the planes 14 and 15 at ecs parts 11A, 11B, has the advantage of allowing the magnetic fields to escape, and to further reduce residual magnetization.

La figure 3 illustre une géométrie optimisée alternative, dérivée de celle de la figure 2. Dans ce cas, les parties de support les plus longues, de la partie saillante principale 11, mais aussi des autres parties 11A, 11B, sont découpées et comportent des découpes 18, notamment sous forme de fentes, pour induire une auto-démagnétisation partielle en absence du champ externe. Ces découpes 18 s'étendent selon une direction parallèle à l'axe principal DP. Comme précédemment, les parties les plus longues, utilisées comme support, ont un rapport de forme important, la dimension la plus grande étant orientée avec son axe principal DP dans la direction orthogonale à la direction d'aimantation préférentielle DA de l'environnement du mouvement. De préférence, la profondeur des découpes 18 est supérieure ou égale à la moitié de la longueur de la partie 11 ou 11A considérée dépassant le rayon moyen de la partie cylindrique de l'arbre 1.The figure 3 illustrates an optimized alternative geometry, derived from that of the figure 2 . In this case, the longest support parts, the main projection 11, but also the other parts 11A, 11B, are cut and include cutouts 18, especially in the form of slots, to induce a partial self-demagnetization in absence of the external field. These cuts 18 extend in a direction parallel to the main axis DP. As before, the longest parts, used as support, have an important aspect ratio, the largest dimension being oriented with its main axis DP in the direction orthogonal to the direction of preferential magnetization DA of the environment of the movement . Preferably, the depth of the cuts 18 is greater than or equal to half the length of the portion 11 or 11A considered exceeding the average radius of the cylindrical portion of the shaft 1.

Même si l'exécution délimitée par des surfaces 14 et 15 qui sont des plans parallèles est très favorable, en termes de résultat comme de coût de production, il faut remarquer que, dès qu'on a un rapport de forme supérieur à 2, selon l'invention, une direction d'aimantation préférentielle dans le plan xy est établie, ce que confirment les simulations par éléments finis.Even if the execution delimited by surfaces 14 and 15 which are parallel planes is very favorable, in terms of result and production cost, it should be noted that, as soon as we have a form ratio greater than 2, according to the invention, a preferred magnetization direction in the xy plane is established, which is confirmed by the finite element simulations.

De façon préférée, pour éviter la création de balourds, l'arbre 1 selon l'invention est symétrique par rapport à un plan passant par l'axe de pivotement D et parallèle à la direction de l'axe principal DP.Preferably, to avoid the creation of unbalance, the shaft 1 according to the invention is symmetrical with respect to a plane passing through the pivot axis D and parallel to the direction of the main axis DP.

Les surfaces de révolution 19, notamment les pivots et le corps cylindrique de l'arbre du balancier peuvent être identiques aux pivots et au corps cylindrique d'un arbre de balancier traditionnel : les performances mécaniques du composant sont donc inaltérées par rapport aux arbres de balancier existants.The surfaces of revolution 19, including the pivots and the cylindrical body of the balance shaft may be identical to the pivots and the cylindrical body of a traditional balance shaft: the mechanical performance of the component are therefore unaltered compared to the balance shafts existing.

Les arbres présentés sur les figures possèdent une direction préférentielle d'aimantation parallèle à l'axe principal DP et choisie de telle manière à être orthogonale à la direction d'aimantation préférentielle DA de l'environnement du mouvement (quand le balancier spiral est au repos).The shafts shown in the figures have a preferred direction of magnetization parallel to the main axis DP and chosen so as to be orthogonal to the direction of preferential magnetization DA of the environment of the movement (when the balance spring is at rest ).

Cas d'un arbre de balancier traditionnel :Case of a traditional pendulum tree:

En ce qui concerne l'effet résiduel, pour un arbre de balancier traditionnel, deux régimes d'aimantation sont possibles, suite à l'exposition à un champ magnétique intense, notamment sous l'influence d'un champ externe statique puissant (> 5 000 kA/m), capable de saturer l'acier au carbone (20 AP) dont est généralement fabriqué l'arbre de balancier, et orienté orthogonalement à l'axe de pivotement de cet arbre (on néglige le cas où le champ est parallèle à l'axe, parce que ce cas ne produit pas de défauts importants à la chronométrie):

  • premier cas : le mouvement du balancier 10 s'arrête sous le champ externe, et le mouvement 30 est stoppé. Puisque le mouvement s'arrête proche de sa position de repos (généralement à moins de 20°, parce que l'arbre a une symétrie cylindrique et le spiral est amagnétique), le champ rémanent dans l'arbre du balancier est orienté comme le champ externe « vu » depuis la position de repos.
  • deuxième cas : le mouvement ne s'arrête pas, donc l'aimantation de l'arbre a lieu dynamiquement: à chaque oscillation, la direction du champ externe « vu » par l'arbre se modifie, le champ dans la matière subit plusieurs cycles d'hystérèse avec la formation progressive (à chaque cycle) d'un champ rémanent (le champ externe est intense, donc il aimante fortement l'arbre, mais, quand l'orientation de l'arbre change, le même champ externe réduit et réoriente partiellement le champ rémanent créé). A cause de la formation progressive et cyclique d'une aimantation permanente, le champ rémanent finalement formé (au bout de quelques oscillations complètes, c'est-à-dire après 0,5 s à 1 s, selon la fréquence) dans l'arbre sera orienté comme si l'arbre était immobile dans sa position moyenne, c'est-à-dire dans sa position de repos (exactement comme si l'arbre s'était arrêté sous le champ).
With regard to the residual effect, for a traditional balance shaft, two magnetization regimes are possible, following exposure to an intense magnetic field, in particular under the influence of a strong external static field (> 5 000 kA / m), capable of saturating the carbon steel (20 AP) of which the balance shaft is generally manufactured, and oriented orthogonally to the pivot axis of this shaft (neglecting the case where the field is parallel to the axis, because this case does not produce significant chronometry defects):
  • first case: the movement of the balance 10 stops under the external field, and the movement 30 is stopped. Since the movement stops close to its rest position (generally less than 20 °, because the shaft has a cylindrical symmetry and the spiral is non-magnetic), the remanent field in the balance shaft is oriented as the field external "seen" from the rest position.
  • second case: the movement does not stop, therefore the magnetization of the tree takes place dynamically: with each oscillation, the direction of the external field "seen" by the tree is modified, the field in the material undergoes several cycles of hysteresis with the progressive formation (at each cycle) of a remanent field (the external field is intense, so it strongly magnetizes the tree, but, when the orientation of the tree changes, the same external field reduces and partially redirects the created remnant field). Because of the progressive and cyclic formation of a permanent magnetization, the remanent field finally formed (after a few complete oscillations, that is to say after 0.5 s to 1 s, depending on the frequency) in the The tree will be oriented as if the tree were motionless in its middle position, that is, in its rest position (exactly as if the tree had stopped under the field).

Indépendamment de l'arrêt sous champ du mouvement, le champ rémanent sera orienté préférablement comme le champ externe tandis que le champ rémanent créé dans l'environnement du mouvement sera orienté selon l'orientation des composants ferromagnétiques fixes (barrettes, vis, ponts), selon la direction d'aimantation préférentielle DA.Independently of the arrest in field of the movement, the remanent field will be oriented preferably like the external field while the remanent field created in the environment of the movement will be oriented according to the orientation of the fixed ferromagnetic components (bars, screws, bridges), according to the direction of preferential magnetization DA.

Après l'élimination du champ externe, un couple magnétique résiduel agit sur l'arbre de balancier comme sur une aiguille de boussole. Le défaut de marche dépend de la symétrie du couple magnétique par rapport à la position de repos du balancier (angle d'oscillation = 0): si le couple est une fonction impaire de l'angle, le défaut de marche est maximum, si le couple est une fonction paire de l'angle, le défaut de marche est nul (mais ce dernier résultat est très improbable pour un arbre traditionnel).After the elimination of the external field, a residual magnetic torque acts on the balance shaft as on a compass needle. The operating fault depends on the symmetry of the magnetic torque relative to the rest position of the balance (oscillation angle = 0): if the torque is an odd function of the angle, the running fault is maximum, if the torque is an even function of the angle, the walking defect is zero (but this last result is very unlikely for a traditional tree).

Cas d'un arbre de balancier selon l'invention:Case of a balance shaft according to the invention:

L'effet résiduel pour un arbre 1 optimisé géométriquement selon l'invention est différent de celui constaté pour un arbre traditionnel.The residual effect for a geometrically optimized shaft 1 according to the invention is different from that observed for a traditional tree.

Les arbres 1 représentés en figure 1 et en figure 2 présentent un rapport de forme d'environ 2. Pour des arbres ayant un rapport de forme de 2 ou supérieur à 2, les régimes d'aimantation possibles sont :

  • premier cas : le mouvement s'arrête sous le champ externe. La présence d'une direction d'aimantation préférentielle affaiblit l'aimantation dans la direction orthogonale.
  • deuxième cas : le mouvement ne s'arrête pas, donc l'aimantation de l'arbre a lieu dynamiquement: à chaque oscillation, la direction du champ externe « vu » par l'arbre se modifie, le champ dans la matière subit plusieurs cycles d'hystérèse avec la formation progressive (à chaque cycle) d'un champ rémanent. A cause de la présence d'une direction d'aimantation préférentielle, l'aimantation sera :
  • orientée selon cette direction, si le champ externe est orienté selon une direction quelconque sauf la direction exactement orthogonale ;
  • orientée dans la direction orthogonale mais très faible, si le champ externe est orienté dans la direction orthogonale à l'axe principal DP de l'arbre.
The trees 1 represented in figure 1 and in figure 2 have a shape ratio of about 2. For shafts having a shape ratio of 2 or greater than 2, the possible magnetization regimes are:
  • first case: the movement stops under the external field. The presence of a preferred magnetization direction weakens the magnetization in the orthogonal direction.
  • second case: the movement does not stop, therefore the magnetization of the tree takes place dynamically: with each oscillation, the direction of the external field "seen" by the tree is modified, the field in the material undergoes several cycles of hysteresis with the progressive formation (at each cycle) of a remnant field. Due to the presence of a preferred magnetization direction, the magnetization will be:
  • oriented in this direction, if the external field is oriented in any direction except the exact orthogonal direction;
  • oriented in the orthogonal direction but very weak, if the external field is oriented in the direction orthogonal to the main axis DP of the shaft.

Puisque l'axe principal DP de l'arbre 1 est orthogonal à la direction préférentielle d'aimantation DAP de l'environnement, pour presque toutes les orientations possibles du champ externe (sauf l'orientation selon la direction préférentielle d'aimantation DAP de l'environnement) le couple magnétique résiduel résultant sur l'arbre1 est une fonction paire de l'angle d'oscillation, ce qui rend presque nul le défaut de marche résiduel.Since the main axis DP of the shaft 1 is orthogonal to the preferred direction of magnetization DAP of the environment, for almost all possible orientations of the external field (except the orientation in the preferred direction of magnetization DAP of the environment) the resulting residual magnetic torque on the shaft1 is an even function of the oscillation angle, which makes the residual run fault almost null.

Si le champ est orienté exactement selon la direction préférentielle d'aimantation de l'environnement DAP, l'arbre est aimanté dans la même direction, donc orthogonalement à l'axe principal DP, mais dans ce cas son aimantation est faible, inférieure à 0,2 T, comme le montre la figure 4 qui illustre la répartition du champ rémanent, après aimantation à 0,2 T selon la direction orthogonale a l'axe principal DP, d'un arbre 1 de balancier optimisé en acier 20 AP. Le couple magnétique est, dans ce cas, une fonction impaire de l'angle d'oscillation, mais il est entre 10 et 100 fois (en dépendance de la géométrie) plus faible que le couple agissant sur un arbre traditionnel, tel que visible sur la figure 5, qui illustre, sous forme d'un graphe, la comparaison des couples magnétiques exercés sur un arbre de balancier traditionnel selon le graphe GT représenté en trait interrompu, et sur un arbre 1 optimisé selon l'invention selon le graphe GO est représenté en trait continu. En abscisse figure l'angle en degrés, et en ordonnée le couple exercé sur le balancier, en mN.mm . Le défaut de marche résiduel est alors réduit d'un facteur entre 3 et 10.If the field is oriented exactly in the preferred direction of magnetization of the DAP environment, the shaft is magnetized in the same direction, thus orthogonal to the main axis DP, but in this case its magnetization is low, less than 0.2 T, as shown in figure 4 which illustrates the distribution of the remanent field, after magnetization at 0.2 T in the direction orthogonal to the main axis DP, of an optimized steel pendulum shaft 1 AP. The magnetic torque is, in this case, an odd function of the oscillation angle, but it is between 10 and 100 times (depending on the geometry) lower than the torque acting on a traditional tree, as visible on the figure 5 , which illustrates, in the form of a graph, the comparison of the magnetic pairs exerted on a traditional balance shaft according to the graph GT shown in broken lines, and on a tree 1 optimized according to the invention according to the graph GO is shown in a line continued. On the abscissa is the angle in degrees, and in ordinate the torque exerted on the balance, in mN.mm. The residual run error is then reduced by a factor between 3 and 10.

Indépendamment de la direction du champ externe, l'optimisation géométrique de l'arbre permet donc de réduire considérablement le défaut de marche résiduel.Independently of the direction of the external field, the geometrical optimization of the shaft thus makes it possible to considerably reduce the residual running error.

De préférence, la matière de l'arbre 1 est magnétiquement homogène dans la réalisation simple illustrée par les figures. Cette exécution particulière n'exclut nullement des réalisations où l'arbre 1 est magnétiquement inhomogène.Preferably, the material of the shaft 1 is magnetically homogeneous in the simple embodiment illustrated by the figures. This particular embodiment does not exclude the embodiments where the shaft 1 is magnetically inhomogeneous.

L'invention apporte des avantages conséquents :

  • champ d'arrêt sous-champ augmenté pour les montres avec spiral, corps d'ancre et roue d'échappement amagnétique ;
  • effet résiduel réduit pour les montres avec spiral, corps d'ancre et roue d'échappement amagnétique ;
  • performances mécaniques identiques aux montres de l'état actuel de la technique.
The invention provides substantial advantages:
  • increased subfield field of arrest for watches with spiral, anchor body and non-magnetic escape wheel;
  • reduced residual effect for watches with spiral, anchor body and non-magnetic escape wheel;
  • mechanical performance identical to watches of the current state of the art.

L'invention permet, ainsi, de modifier la géométrie de l'arbre du balancier (et non pas du balancier tout entier), parce que l'arbre est en général le seul composant magnétique, qu'il est difficile de le remplacer par un matériau amagnétique. Et c'est bien l'influence de l'arbre lui-même qu'il faut réduire, ce but est atteint par l'invention.The invention thus makes it possible to modify the geometry of the balance shaft (and not the whole balance), because the shaft is generally the only magnetic component, which is difficult to replace with a non-magnetic material. And it is the influence of the tree itself that must be reduced, this goal is achieved by the invention.

Il n'est pas nécessaire d'adapter la géométrie des composants se montant sur l'arbre de balancier, car les surfaces de support sont maintenues, même si elles sont localement modifiées par la mise en oeuvre de l'invention, par rapport à un balancier traditionnel.It is not necessary to adapt the geometry of the components mounted on the balance shaft, because the support surfaces are maintained, even if they are locally modified by the implementation of the invention, compared to a traditional balance.

En somme, même si on peut naturellement envisager, autour du concept inventif de l'invention, différentes constructions très spécifiques selon le cas d'espèce, et surtout pour simplifier la fabrication et la fixation des composants, l'important est d'appliquer ce concept de base: il faut définir une direction préférentielle d'aimantation de l'arbre de balancier, adaptée à la direction d'aimantation préférentielle de l'environnement. La manière la plus simple est d'avoir une géométrie prismatique plutôt que cylindrique (avec un facteur de forme de 2 ou plus).In short, even if we can naturally consider, around the inventive concept of the invention, different very specific constructions depending on the particular case, and especially to simplify the manufacture and fixing of the components, the important thing is to apply this basic concept: it is necessary to define a preferred direction of magnetization of the balance shaft, adapted to the direction of preferential magnetization of the environment. The simplest way is to have prismatic rather than cylindrical geometry (with a form factor of 2 or more).

Pour arriver à ce résultat, il a fallu étudier le mécanisme d'aimantation d'un composant ferromagnétique en mouvement, un problème qui n'a jamais été attaqué en horlogerie et qui a été étudié dans le domaine des machines rotatives lourdes seulement à partir des années 2000.
L'homme du métier peut consulter à ce sujet différents articles :

  • Diala E.A. (2008), "Magnetodynamic vector hysteresis models for steel laminations of rotating electrical machnies", Helsinki University of Technology, ISBN 978-951-22-9276-9 / 978-951-22-9277-6, ISSN 1795-2239/1795-4584 .
  • Fuzi, J. (1999), "Computationally efficient rate dépendent hysteresis model", COMPEL, 18, 445-457 .
  • Zirka, S. E., Moroz, Y. I., Marketos, P., and Moses, A. J. (2004c), "Properties of dynamic Preisach models"', Physica B: Condensed Matter, 343, 85-89 .
  • Zirka, S. E., Moroz, Y. I., Marketos, P., and Moses, A. J. (2005b), "A viscous-type dynamic hystérésis model as a tool of loss séparation in conducting ferromagnetic laminations", IEEE Trans. Magn., 41, 1109-1111 .
To arrive at this result, it was necessary to study the mechanism of magnetization of a moving ferromagnetic component, a problem which has never been attacked in watchmaking and which has been studied in the field of heavy rotary machines only from the 2000s.
The skilled person can consult on this subject different articles:
  • Diala EA (2008), "Magnetodynamic vector hysteresis models for steel laminates of rotating electrical machnies", Helsinki University of Technology, ISBN 978-951-22-9276-9 / 978-951-22-9277-6, ISSN 1795-2239 / 1795-4584 .
  • Fuzi, J. (1999), "Computationally efficient rate depend on hysteresis model", COMPEL, 18, 445-457 .
  • Zirka, SE, Moroz, YI, Marketos, P., and Moses, AJ (2004c), "Properties of Dynamic Preisach Models", Physica B: Condensed Matter, 343, 85-89 .
  • Zirka, SE, Moroz, YI, Marketos, P., and Moses, AJ (2005b), "A viscous-type dynamic hysteresis model as a tool of loss separation in conducting ferromagnetic laminations", IEEE Trans. Magn., 41, 1109-1111 .

Claims (8)

  1. Timepiece mechanism (20) including a preferred direction of magnetisation (DA) and including a movable timepiece component (10) including an arbor (1) intended to pivot about a pivot axis (D) and including at least one addendum (11) of greater radius (RMAX) about said pivot axis (D), where at least said addendum (11) is delimited, on either side of said pivot axis (D), by two surfaces (14; 15), which define, projecting along a perpendicular plane to said pivot axis (D), a profile (12) inscribed in a rectangle (R) wherein the ratio of the length (LR) to the width (LA) defines an aspect ratio which is greater than or equal to 2, the direction of said length (LR) defining a main axis (DP), where at least a portion (11, 11A) of said profile inscribed in said rectangle and delimited on two opposing sides by said two surfaces (14; 15), includes at least one blanked area (18) centred on said pivot axis (D) and extending along said main axis (DP), said arbor (1) being made of steel and said movable component (10) being arranged to oscillate about a rest position defined by a rest plane passing through said pivot axis (D), and in which rest position said main axis (DP) occupies a determined angular position with respect to said rest plane, said movable component (10) being returned to said rest position by elastic return means, and in which rest position said main axis (DP) is orthogonal to said preferred direction of magnetisation (DA).
  2. Mechanism (20) according to claim 1, characterised in that said arbor (1) includes at least one further portion (11A) having, projecting along a perpendicular plane to said pivot axis (D), a profile inscribed in said rectangle delimited on two opposing sides by said two surfaces (14; 15).
  3. Mechanism (20) according to claim 1 or 2, characterised in that said two surfaces (14; 15) are symmetric with respect to said pivot axis (D).
  4. Mechanism (20) according to claim 3, characterised in that said two surfaces (14; 15) are plane and parallel with said pivot axis (D).
  5. Mechanism (20) according to one of claims 1 to 4, characterised in that said arbor (1) has a high saturation field with a value (Bs) higher than 1 T, a maximum magnetic permeability (µR) greater than 50, and a coercive field (Hc) higher than 3 kA/m.
  6. Mechanism (20) according to one of claims 1 to 5, characterised in that said mechanism (20) is an escapement mechanism, and in that said movable component (10) is a balance wheel returned to said rest position by at least one balance spring, and in that said arbor (1) is a balance staff.
  7. Timepiece movement (30) including at least one mechanism (20) according to one of claims 1 to 6.
  8. Watch (40) including at least one timepiece movement (30) according to claim 7, or/and including at least one mechanism (20) according to one of claims 1 to 6.
EP13161123.8A 2013-03-26 2013-03-26 Arbour of a mobile with optimised geometry in magnetic environment Active EP2784602B1 (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
EP13161123.8A EP2784602B1 (en) 2013-03-26 2013-03-26 Arbour of a mobile with optimised geometry in magnetic environment
CH00665/13A CH707791B1 (en) 2013-03-26 2013-03-26 Mobile tree with geometry configured for magnetic environment.
CN201480018602.8A CN105074585B (en) 2013-03-26 2014-03-17 The heart axle of movable member with the geometry optimized in magnetic environment
EP14713783.0A EP2979140B1 (en) 2013-03-26 2014-03-17 Mobile arbor having a shape optimized in a magnetic environment
PCT/EP2014/055268 WO2014154511A2 (en) 2013-03-26 2014-03-17 Train arbor having a shape optimized in a magnetic environment
US14/779,883 US9372473B2 (en) 2013-03-26 2014-03-17 Timepiece mechanism comprising a movable oscillating component with optimised geometry in a magnetic environment
JP2016504561A JP6034991B2 (en) 2013-03-26 2014-03-17 Clock mechanism with movable oscillating components having geometry optimized in a magnetic environment
HK16105565.6A HK1217774A1 (en) 2013-03-26 2016-05-16 Train arbor having a shape optimized in a magnetic environment

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EP13161123.8A EP2784602B1 (en) 2013-03-26 2013-03-26 Arbour of a mobile with optimised geometry in magnetic environment

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EP2784602B1 true EP2784602B1 (en) 2018-12-05

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EP2784601B1 (en) * 2013-03-26 2017-09-13 Montres Breguet SA Arbor of a pivotable clock mobile
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US9372473B2 (en) 2016-06-21
JP6034991B2 (en) 2016-11-30
CN105074585A (en) 2015-11-18
JP2016517955A (en) 2016-06-20
HK1217774A1 (en) 2017-01-20
EP2979140B1 (en) 2017-10-25
CH707791A2 (en) 2014-09-30
CN105074585B (en) 2017-10-24
WO2014154511A2 (en) 2014-10-02
WO2014154511A3 (en) 2014-12-31
EP2979140A2 (en) 2016-02-03
EP2784602A1 (en) 2014-10-01
US20160085214A1 (en) 2016-03-24
CH707791B1 (en) 2017-05-15
WO2014154511A4 (en) 2015-02-19

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