EP3882713B1 - Timepiece movement comprising an escapement provided with a magnetic system - Google Patents

Description

Technical area

The invention relates to watch movements comprising an escapement equipped with a magnetic system. More particularly, the invention relates to an escapement provided with a magnetic coupling system between an escapement wheel and an anchor separate from the mechanical resonator, this anchor having an axis of rotation different from that of the mechanical resonator. As with a Swiss anchor, the anchor presents an alternating movement which is synchronous with the periodic movement of the mechanical resonator, but different. Magnetic escapement means an escapement provided with magnets arranged partly on the lever and partly on the escapement wheel so as to generate a magnetic coupling between the lever and the escapement wheel.

Technology background

Various horological movements with a magnetic escapement have already been proposed in patent applications. With regard to magnetic escapements comprising a lever separate from the mechanical resonator, mention may be made of the document EP 3 208 667 , which describes a magnetic escapement with a pallet mechanically coupled to the mechanical resonator and magnetically to the escapement wheel, the latter having two annular magnetic tracks formed by a planar and continuous magnetized structure, which defines ramps of magnetic potential energy and magnetic barriers for at least one magnetic pallet of the anchor which is arranged to alternately follow sections of the two magnetic tracks, this magnetic pallet being formed by a magnet.

Magnetic escapements often present a problem when starting. When the barrel is disarmed and the watch movement stops, the escapement wheel ceases to be driven in rotation by the barrel and the oscillation of the mechanical resonator is then strongly damped then the mechanical resonator stops in a position angular corresponding to its rest position or close to it. Indeed, the stop position of the mechanical resonator can vary, in a certain angular zone, around its rest position depending on the angular position of the escape wheel when stopped, given the magnetic coupling of the latter. with the anchor. This angular zone is limited by the two stop positions of the anchor against two pins limiting its reciprocating movement, because the pin of the mechanical resonator is located in the fork of the anchor when this resonator is finally stationary.

At start-up, when the escape wheel starts to turn again and to exert a torque which increases as the barrel is wound up, it is very likely, given the magnetic system provided in certain magnetic escapements, in particular in those described in the document EP 3 208 667 , that the escapement is not self-starting. As the mechanical resonator does not yet oscillate, it cannot therefore perform its function of releasing the anchor to drive it into an alternating movement, so that the escapement is not able to provide sufficient energy to the mechanical resonator so that a normal oscillation of the latter is established. In addition, depending on the magnetic system provided, it is possible that the lever and the escape wheel block each other by a magnetic force of repulsion at certain angular positions of the escape wheel, due to the fact that the mechanical resonator does not not or not yet oscillating normally. Thus, it is necessary to find a solution to ensure effective starting of an escapement provided with a magnetic system during winding of the barrel after the watch movement has been stopped.

Summary of the invention

In general, the invention relates to a horological movement comprising a mechanical resonator and an associated escapement which comprises an escapement wheel having a first axis of rotation and an pallet separated from the mechanical resonator and having a second axis of rotation which is different from that of the mechanical resonator. The mechanical resonator is coupled to the anchor in such a way that, when this mechanical resonator exhibits an oscillation, the anchor undergoes an alternating movement between two rest positions in which it remains alternately during successive time intervals. The anchor comprises at least one magnetic pallet formed of a magnet and the escape wheel comprises a periodic magnetized structure which defines a plurality of increasing ramps of magnetic potential energy for said magnetic pallet, each of these increasing ramps of energy magnetic potential being provided so that said magnetic pallet can climb it when the anchor is in a corresponding rest position among the two rest positions and a force torque supplied to the escape wheel is equal to a torque of nominal force or within a range of values which is provided for normal operation of the watch movement. Said magnetic pallet and the periodic magnetized structure are arranged such that the anchor experiences an impulse of magnetic force in the direction of its reciprocating motion, after said magnetic pallet has climbed any one of said increasing ramps of magnetic potential energy, when the anchor swings from one of the two rest positions having allowed this magnetic pallet to climb said any increasing ramp of magnetic potential energy towards the other rest position.

To overcome the drawbacks mentioned above and ensure efficient and rapid self-starting of an escapement provided with a magnetic system designed to supply pulses of magnetic force to the mechanical resonator via the lever, the escapement wheel comprises at at least a first part remote from the first axis of rotation and the anchor comprises at least a second part remote from the second axis of rotation. Then, when the mechanical resonator is at rest, the anchor has, for any angular position θ of the escape wheel when stationary, an angular position of equilibrium β _ER (θ) which depends on this angular position θ. According to the invention, for any angular position θ of at least one range of angular positions of the escape wheel, the first and second remote parts are in contact with each other while the mechanical resonator is at rest and the anchor is in the corresponding β _ER (θ) equilibrium angular position, the first and second remote parts being arranged such that the β _ER (θ) angular equilibrium position of the anchor is, over at least a part of each range of angular positions among said at least one range of angular positions, a monotonic function of the angular position θ of the escape wheel which moves away from a mid-position of the lever with a variation of said angular position θ in the direction of rotation provided for the escape wheel, this middle position defining a zero angular position for the lever at equal angular distance from its two rest positions. In addition, a maximum absolute value AM _E of the angular position of equilibrium β _ER (θ) of the anchor over said at least one angular range is strictly less than an absolute angular value β _Max of the two rest positions.

According to a first particular embodiment, each first remote part among said at least one first remote part has, in a system of polar coordinates perpendicular to said first axis of rotation and centered on the latter, a first inclined surface so that each of said at least one second remote part can slide on at least a part of this first inclined surface while the escape wheel passes through a corresponding range of angular positions among said at least one range of angular positions and while the lever angularly follows a curve defined by the corresponding angular positions of equilibrium β _ER (θ).

According to a second particular embodiment, which can be combined with the first particular embodiment, each second distant part among said at least one second distant part has, in the aforementioned polar coordinate system, a second inclined surface when the anchor is in any angular position of equilibrium β _ER (θ) corresponding to any angular position of a range of angular positions, among said at least one range of angular positions, in which this second remote part is in contact with a first part one of said at least one first distant part, the second inclined surface being configured such that each first distant part of said at least one first distant part can slide on at least a part of this second inclined surface while the escape wheel crosses a range of angular positions, among said at least one range of positi angular ons, which relates to the first and second distant parts considered and that the anchor angularly follows a curve defined by the corresponding angular positions of equilibrium β _ER (θ).

According to a general embodiment, said at least one second remote part of the anchor is formed by two mechanical pallets and the escape wheel comprises a plurality of remote parts constituting said at least one first remote part, this plurality of remote parts being respectively associated with said plurality of increasing ramps of magnetic potential energy. Then, the two mechanical pallets are respectively associated with two magnetic pallets formed by two magnets arranged so as to be each at least periodically magnetically coupled, in repulsion, with the periodic magnetized structure of the escape wheel. In a main variant, the plurality of distant parts is formed by a plurality of teeth and the two mechanical pallets are configured so as to form, in normal operation of the mechanical movement, mechanical stops for this plurality of teeth, so as to improve the exhaust operation or to allow a step-by-step rotation of the escape wheel which is synchronized with the reciprocating movement of the lever and therefore with the oscillation of the mechanical resonator.

In an improved variant of the general embodiment, the lever and the escape wheel are arranged so that, when the lever presents said reciprocating movement and the force torque supplied to the escape wheel is equal to said nominal force or included in at least an upper part of said range of values expected in normal operation and after one of the two magnetic pallets has climbed any one of said increasing ramps of magnetic potential energy following tilting of the anchor in its corresponding rest position, the tooth of the escape wheel associated with said any one of said increasing ramps of magnetic potential energy undergoes at least a first impact on one of the two mechanical lever pallets. This first shock momentarily prevents rotation of the escape wheel beyond an angular stop position, defined by said first or second mechanical pallet, before a next rocking of the anchor and it intervenes in such a way as to dissipate at least partially a kinetic energy of the escape wheel acquired following said tilting. In a preferred variant, the escapement is arranged so that, following the first impact and before the next rocking of the lever, the escapement wheel stops momentarily.

Brief description of figures

• Les Figures 1A à 1I montrent partiellement un mouvement horloger, selon un mode de réalisation de l'invention, avec un échappement hybride, configuré pour assurer un auto-démarrage de l'échappement, dans des positions successives ;
• La figure 2 représente schématiquement le parcours angulaire périodique β(θ) de l'ancre de l'échappement hybride de la Figure 1A en fonction de la position angulaire θ de la roue d'échappement lorsque le mouvement horloger en en fonctionnement normal et lorsque le résonateur mécanique est en repos et la roue d'échappement à l'arrêt.

The invention will be described below in more detail using the accompanying drawings, given by way of non-limiting examples, in which:

• The Figures 1A to 1I partially show a watch movement, according to one embodiment of the invention, with a hybrid escapement, configured to ensure self-starting of the escapement, in successive positions;
• The figure 2 schematically represents the periodic angular path β(θ) of the anchor of the hybrid escapement of the Figure 1A as a function of the angular position θ of the escape wheel when the watch movement is in normal operation and when the mechanical resonator is at rest and the escape wheel is stationary.

Detailed description of the invention

With the aid of the Figures, an embodiment of a watch movement according to the invention will be described below, which is of the mechanical type and comprises a mechanical resonator 2, of which only the axis 4, the small plate 6 having a notch and pin 10 have been shown. The watch movement includes an escapement 12 which is associated with the mechanical resonator whose small plate and peg are elements forming this escapement. The escapement 12 further comprises an escape wheel 16 and an pallet 14 which is a separate member from the mechanical resonator and whose axis of rotation is different from that of this mechanical resonator.

The anchor 14 is formed, on the one hand, of a rod 20 terminated by a fork 18, comprising two horns 19a and 19b, and by a dart 8 and, on the other hand, of two arms 24 and 26 whose free ends respectively form two mechanical pallets 28 and 29. The two mechanical pallets respectively support two magnets 30 and 32 which form two magnetic pallets of the anchor 14. The mechanical resonator 2 is coupled to the anchor so that, when the resonator mechanism oscillates normally, this anchor undergoes an alternating movement, synchronized with the oscillation of the mechanical resonator, between two rest positions, defined by two limiting pins 21 and 22, in which the anchor remains alternately during successive time intervals.

The escape wheel 16 comprises a periodic magnetized structure 36 which is arranged on a disc 34 preferably made of non-magnetic material (which does not conduct magnetic fields). The structure 36 has globally circular magnetized portions 38 defining increasing ramps of magnetic potential energy for the two magnetic pallets 30, 32, which each have an axial magnetization with a polarity opposite to that of the axial magnetization of the periodic magnetized structure so as to generate magnetic repulsion between the magnetic pallets and the magnetized structure. Each magnetized portion 38 has a monotonically increasing width. In particular, the width of the magnetized portions increases, over their entire useful length, linearly as a function of the central angle. According to an advantageous variant, the periodic magnetized structure 36 is arranged so that its outer periphery is circular, the arcuate portions 38 of this magnetized structure having the same configuration and being arranged circularly around the axis of rotation of the wheel exhaust.

In general, each increasing ramp of magnetic potential energy is provided so that each of the two magnetic pallets can climb it when the anchor is in a given rest position, among its two rest positions, and that a torque of force supplied to the escape wheel is substantially equal to a torque of nominal force (case of a mechanical movement equipped with a constant force system for driving the escape wheel) or included in a range of values provided to ensure normal operation of the watch movement (case of a conventional mechanical movement having a variable force torque applied to the escape wheel depending on the level of winding of the barrel or barrels if several are provided in series). The increasing ramps of magnetic potential energy are climbed, when the anchor undergoes an alternating movement between its two rest positions and when the force torque supplied to the escape wheel is equal to said nominal force torque or included in the range predicted values for this force couple in normal operation, successively by each of the first and second magnetic pallets when the anchor is respectively in its first and second rest positions, and alternately by these first and second magnetic pallets during the reciprocating movement of the anchor. The two magnetic paddles and the increasing ramps of magnetic potential energy are arranged so that the anchor can experience an impulse of magnetic force in the direction of its movement, after any one of the two magnetic paddles has climbed any of said ramps increasing magnetic potential energy, when the anchor swings from the rest position corresponding to any ramp of magnetic potential energy to its other rest position. Curve 52 shown in Figure 2 gives the angular position β _FN (θ) of the lever, in normal operation of the watch movement, as a function of the angular position θ of the escape wheel. The horizontal sections of curve 52 correspond to anchor 14 in one or the other of its two rest positions (angular positions +/- β _Max ) and the rising and falling sides correspond to the alternating swings of this anchor, between its two rest positions, during which the anchor successively undergoes pulses of magnetic force, which enables it to supply sustain pulses to the mechanical resonator via the fork 18.

The periodic magnetized structure 36 also defines for each of the two magnetic pallets magnetic barriers 46 which are located respectively following the increasing ramps of magnetic potential energy defined by the magnetized portions 38, these magnetic barriers being formed in particular by magnetic pads 46 of the structure 36 whose radial dimension is substantially equal to or greater than the longitudinal dimension of each of the two magnets 30 and 32 forming the magnetic pallets of the anchor. Each magnetic pad/magnetic barrier is arranged in such a way as to exert a couple of magnetic forces on the escape wheel 16, having a direction opposite to that said torque of force supplied to this escapement wheel, when this escapement wheel is in an angular position of balance of the forces which are exerted on it while one or the other of the two magnetic pallets is located at the top of the magnetic potential energy ramp / at the widest end of the magnetized portion 38 which precedes the magnetic barrier / the magnetic pad 46 considered. The arrangement of the magnetic barriers is provided so that the torque of magnetic force which is exerted on the escape wheel in each angular position of equilibrium of the forces is greater than a maximum torque of magnetic force generated by the ramp of magnetic potential energy/the magnetized portion 38 preceding the magnetic barrier considered before the escape wheel reaches the angular position of force equilibrium.

The escape wheel further comprises protrusions which are respectively associated with the increasing ramps of magnetic potential energy. These projecting parts are formed by teeth 42 extending radially from a plate 40 which is integral with the escape wheel and located above the disc 34 carrying the magnetic structure 36. These teeth are located respectively following the portions magnetized 38, on the side of their widest end, and are partially superimposed on the corresponding magnetic pads 46. The teeth 42 are arranged to cooperate on starting with the mechanical pallets 28 and 29, as will be explained in more detail later. The teeth and mechanical pallets are formed by a non-magnetic material.

In the advantageous variant shown, the teeth extend in a general plane in which the two mechanical pallets 28, 29 of the anchor also extend. The two magnets 30, 32 are respectively supported by the two mechanical pallets and are also located in said general plane. The figures only show a lower magnetized structure, located below the general plane. However, in an advantageous variant, the escape wheel also comprises a structure magnetized upper, of the same configuration as the lower magnetized structure and supported by an upper disc preferably formed of a non-magnetic material. The lower and upper magnet structures together form the periodic magnet structure. They have the same magnetic polarity, opposite to that of the two magnets of the anchor, and are arranged on either side of the geometric plane in which these two magnets forming the two magnetic pallets are located, preferably at the same distance.

Before describing in more detail the main object of the present invention, particular characteristics of the escapement of the advantageous embodiment considered will be described, which make it possible to improve its normal operation (that is to say stable operation , occurring after a start-up phase, with a force torque M _RE supplied to the escape wheel substantially which is equal to a nominal force torque or included in a range of values provided for ensuring the normal operation of the watch movement, in particular correct stepping rotation of the escape wheel). The lever 14 and the escape wheel 16 are arranged so that, in normal operation, one of the teeth 42 of the escape wheel undergoes at least one shock on one or the other of the two mechanical pallets after the pallet corresponding magnetic climbed any of the increasing ramps of magnetic potential energy following a tilting of the anchor. This impact occurs in such a way as to at least partially dissipate a kinetic energy of the escape wheel acquired following said tilting. The teeth of the escape wheel are designed to absorb kinetic energy from this escape wheel, at each step of the escape wheel after an accumulation of magnetic potential energy in the escapement for a next pulse of escapement. maintenance of the mechanical resonator, and to thereby limit terminal oscillation during each step of its step-by-step rotation.

In the case of a conventional mechanical watch movement, namely without a constant-force escape wheel drive system, it is expected that, for the entire range of values PV _M of the force torque M _RE supplied to the escape wheel in normal operation, at least a first impact between any one of the teeth 42 of the escape wheel and any mechanical palette of the anchor occurs after the corresponding magnetic palette has climbed one of the increasing energy ramps magnetic potential associated with this corresponding magnetic paddle and with the tooth having undergone said at least one first shock.

In a main variant, the escapement is arranged so that, following said at least one first shock of any one of the two mechanical pallets against any one of the teeth of the escape wheel, this first shock momentarily stopping the rotation of the escapement wheel beyond an angular stop position, and before a next rocking of the lever, the escapement wheel comes to a standstill in an angular stop position which corresponds by definition to a position of equilibrium forces present.

In a preferred variant, in normal operation and once the escape wheel has momentarily stopped, a tooth 42 presses against a mechanical stop of the anchor formed by one or the other of the two mechanical pallets. The escapement is therefore a hybrid escapement, that is to say magnetic and mechanical. For a conventional movement, provision is therefore made, in normal operation and for the entire range of values PV _M of the force torque M _RE , for the escape wheel to stop momentarily, after at least a first shock from any of its teeth against any one of the two mechanical pallets and before a subsequent rocking of the anchor, to an angular stop position in which any tooth presses against any mechanical pallet. Each angular stop position is thus defined by a tooth resting against a mechanical pallet.

In a general variant, for at least an upper part of said range of values PV _M of said force torque M _RE supplied to the escape wheel in normal operation, at least a first impact between any one of the teeth of the escape wheel escapement and any mechanical pallet of the anchor intervenes after the corresponding magnetic pallet has climbed one of the increasing ramps of magnetic potential energy associated with this corresponding magnetic pallet and the tooth concerned. In a particular variant of the general variant, when the force couple M _RE has a value in at least one upper zone of said upper part of the range of values PV _M , provision is made for the tooth having undergone said at least one first shock presses, once momentarily immobile in the corresponding angular stop position, against the mechanical pallet on which it has stumbled.

Thereafter, the object of the invention will be described more precisely. In general, the escape wheel comprises at least a first part distant relative to its axis of rotation, and the anchor comprises at least a second part distant relative to its axis of rotation. In the embodiment shown, the escapement wheel comprises a plurality of first remote parts which are formed by the teeth 42, and the lever comprises two second remote parts formed respectively by the first and second mechanical pallets 28, 29. When the watch movement is stopped as a result of the barrel spring being disarmed, the escapement wheel 16 is also stopped and the mechanical resonator 2 is quickly at rest (that is to say it is not oscillating and has no kinetic energy). Then, the anchor 14 is for any angular position θ (angular stop position) of the escapement wheel 16 in a corresponding angular position of equilibrium β _ER (θ) which depends on this angular position. Generally speaking, when the mechanical resonator is at rest, it is not necessarily located in its rest position (position of minimum mechanical energy with the hairspring relaxed), because the anchor can exert a certain force on it, from made of the magnetic system of the escapement and/or the mechanical device which is provided within the scope of the invention, and move it into angular positions where the hairspring of this mechanical resonator is then slightly stretched and therefore exerts a small restoring force. In such a case, an equilibrium position is generally determined for the assembly consisting of the escapement and the mechanical resonator for each angular position θ of the escape wheel, and an angular position of equilibrium β _ER (θ) is determined for the anchor. The 50 curve at the Figure 2 , giving the angular position of equilibrium β _ER (θ) of the lever 14 as a function of the angular position θ of the escapement wheel 16, has substantially horizontal sections at a median position, defining a zero angular position for the anchor 14, at equal angular distance from the two rest positions of this anchor which correspond to the two extreme angular values +/- β _Max for the reciprocating movement of the anchor. When the lever 14 is in the middle position '0', the mechanical resonator 2 is in its rest position, so that its balance wheel is then not subjected to any restoring force from the hairspring. In general, in the latter case, it will be noted that there may be some uncertainty on the angular position of equilibrium β _ER (θ) of the anchor near the median value or at this median value, but this uncertainty (or angular zone of possible balance) is very small, of the order of the play of the pin 10 between the two horns 19a and 19b of the fork 18 of the anchor. However, this is not the case in the embodiment represented, because the magnetic system of the escapement 12 maintains the lever substantially in the angular position '0' in the absence of force exerted on the lever by the mechanical resonator stationary in its rest position.

When the barrel of the watch movement is disarmed (i.e. the mainspring of this barrel is relaxed so that the force couple it supplies to the escapement wheel no longer allows it to be driven), the wheel escapement stops in any angular position θ and, after a period of damping of the oscillation of the mechanical resonator 2, the latter is at rest and the lever is in the angular position of equilibrium β _ER (θ ) corresponding. In this situation, ranges of angular positions PC _P1 and PC _P2 of the escapement wheel 16 are provided in which the first and second mechanical pallets 28 and 29 are respectively in contact with a corresponding tooth among the plurality of teeth 42 of the escape wheel. Then, the teeth 42 and the two mechanical pallets 28, 29 are arranged so that the angular position of equilibrium β _ER (θ) of the anchor 14 is, over at least a first part of each of the ranges of angular positions PC _P1 and PC _P2 , a monotonic function of the angular position θ of the escape wheel which moves away from the mid-position '0' of the lever with a variation of this angular position θ in the direction of rotation provided for the escape wheel, as shown in Figure 2 . In addition, a maximum absolute value AM _E is provided for the angular position of equilibrium β _ER (θ) of the anchor over the ranges of angular positions PC _P1 and PC _P2 which is strictly less than an absolute angular value β _Max of the two resting positions of the anchor, as also shown in Figure 2 .

Thanks to the aforementioned characteristics, when the barrel spring is re-wound allowing the escapement wheel 16 to start rotating again in the intended direction of rotation (clockwise Figures 1A to 1l ), at least one of the two mechanical pallets 28, 29 comes into contact with a tooth 42 of the escape wheel which can thus provide the anchor 14 with a couple of mechanical starting forces and therefore a mechanical starting impulse. Thus, rapid self-starting of the escapement 12 and therefore of the mechanical watch movement is made possible.

In particular, the escapement wheel 16 and the lever 14 are arranged so that, when the escapement wheel begins to rotate, in a starting phase, from any angular position while being subjected to a lower starting torque or equal to the torque of force provided for in normal operation, it does not encounter any stop of magnetic or mechanical origin which is likely to stop it before this escape wheel reaches a next range of angular positions PC _P1 or PC _P2 , in particular said at least a first part of this next range of angular positions exhibiting said monotonic function. Moreover, the teeth 42 and the mechanical pallets 28, 29 are configured so that, in said next range of angular positions, the escapement wheel 16 subjected to said starting torque is not stopped by the contact between the tooth and the mechanical pallet concerned but that the tooth concerned can transmit at least a major part of said starting torque to the anchor. It will be noted that the variant shown is special due to the particular magnetic system of the escapement. Indeed, in the absence of teeth 42, the angular position of equilibrium of the lever would remain substantially at zero over a magnetic period P _RE of the escapement wheel, and therefore over a complete revolution of this escapement wheel. . Under these conditions, it is understood that no start-up of the mechanical resonator and the associated escapement can take place without specific means for this purpose being provided, to allow the mechanical resonator to be activated again and at anchor. to present a resultant reciprocating motion.

In a first advantageous variant, shown in Figures 1A to 1C , 1E and 1G , each of the teeth 42 has, in a polar coordinate system R, θ (see Figures 1A to 1I ) perpendicular to the axis of rotation of the escape wheel 16 and centered thereon, a first inclined surface SI ₁ which is inclined so that each of the first and second mechanical pallets 28, 29 can, in a phase of starting, sliding on this first inclined surface while the escapement wheel crosses a corresponding range of angular positions θ, among the ranges of angular positions PC _P1 or PC _P2 , and the lever 14 at least partially follows a portion of the curve 50, which is defined by the angular positions of equilibrium β _ER (θ), corresponding to this range of angular positions. By 'inclined surface' in a polar coordinate system, we understand a surface which is neither radial nor tangential.

In a second advantageous variant, also shown in Figures 1A to 1C , 1E and 1G , each of the two mechanical pallets of the anchor has, in the polar coordinate system R, θ associated with the escapement wheel, a second inclined surface SI ₂ when the anchor is in any angular position of equilibrium β _ER (θ) corresponding to any angular position θ of a range of angular positions, among the ranges of angular positions PC _P1 and PC _P2 , in which the mechanical pallet considered is in contact with one of the teeth 42 of the escape wheel . The second inclined surface SI ₂ is configured so that each of the teeth 42 can, in a starting phase, slide on this second inclined surface while the escape wheel passes through a range of angular positions θ, among the ranges of angular positions PC _P1 and PC _P2 , which relates to the tooth and the mechanical pallet considered, and the anchor 14 follows at least partially a portion of the curve 50, which is defined by the angular positions of equilibrium β _ER (θ) , corresponding to said range of angular positions.

With reference to Figures 1A to 1l , a starting sequence/starting phase of a hybrid escapement 12 according to the invention will finally be described below. These Figures 1A to 1I show a series of successive events occurring when the assembly formed by the mechanical resonator 2 and the escapement 12 is started up during winding of the barrel of the watch movement incorporating this assembly, after the watch movement has stopped because of its mainspring disarmed barrel. To the Figure 1A , the watch movement is stopped, the mechanical resonator at rest and the anchor in a corresponding angular position of equilibrium, which is the median position of the anchor which defines its zero angular position. This angular position of equilibrium equal to '0' ( Figure 2 ), in the absence of contact with a tooth 42, results from the fact that the magnetic paddles 30, 32 are partially superimposed on the magnetized portions 38 of the periodic magnetized structure 36, each in a position corresponding to a radial magnetic force which is positive in the coordinate system poles associated with the escapement wheel, which generates two opposing pairs of magnetic force on the anchor which compensate each other.

To the Figure 1B , on start-up, the escape wheel drive mechanism 16 applies a force torque to this escape wheel, allowing it to start rotating again in the intended clockwise direction, and a tooth 42 then comes into contact with the mechanical palette 28 (event shown in Figure 1B ), so as to generate on this mechanical pallet a tangential force F _TD in a system of polar coordinates r, β associated with the anchor 14, that is to say perpendicular to the axis of rotation of this anchor and centered on this one. In particular, this tangential force F _TD is obtained by the fact that the point of initial contact between the tooth and the mechanical plate is located on at least one of the two inclined surfaces SI ₁ and SI ₂ (see Figure 1C ) exhibited respectively by the tooth 42 and the mechanical pallet 28 in the system of polar coordinates which is associated with the escapement wheel. The escapement wheel continuing to rotate thanks to the starting torque applied to it, the rounded end part of the tooth then slides on the inclined surface SI ₂ of the mechanical pallet 28 (inclined in the polar coordinate system associated with the escape wheel) until the point of contact is located substantially at the bottom of this inclined surface SI ₂ (event shown in Figure 1C ), the tooth 42 exerting a tangential force F _TD throughout the rotation of the escape wheel between the Figure 1B and the Figure 1C , and thus a starting torque on the anchor 14, which transmits at least a major part of the starting torque to the mechanical resonator 2 via a horn of the fork 18. The mechanical resonator thus receives a first mechanical starting impulse allowing it to be activated again, starting an oscillation. In a particular variant, the inclined surfaces SI ₁ and SI ₂ are inclined planes. It will be noted that, at start-up during contact between a tooth and a mechanical pallet, it is advantageous to have, as shown, a magnetic barrier 46 superimposed on the corresponding inclined surfaces SI ₁ and SI ₂ in order to be able to produce a certain magnetic repulsion force on the magnet associated with the mechanical pallet in contact with the tooth. This magnetic repulsion force reduces the contact force between the tooth and the mechanical pallet and therefore the friction when one slides over the other, which opposes the rotation of the escape wheel and therefore the starting . This particular configuration facilitates self-starting which can thus occur for a greater range of torque applied to the escape wheel.

In another variant, similar to the variant shown but with an anchor having longer mechanical pallets, during the starting phase, the inner corner of the mechanical pallet 28, respectively the outer corner of the mechanical pallet 29 begins to slide, when the escape wheel rotates clockwise, on the inclined surface SI ₁ of the tooth and only then does the rounded end part of the tooth slide on the inclined surface SI ₂ of the mechanical pallet, as exposed above. We therefore understand the benefit of having a configuration of the exhaust with the two inclined surfaces SI ₁ and SI ₂ , as shown, where the inclined surface SI ₁ has a slightly steeper slope than that of the inclined surface SI ₂ whereas a tooth and a mechanical pallet are in contact during the start-up phase of the assembly formed by the escapement and the mechanical resonator. In the aforementioned advantageous variants, during the start-up phase, provision is made for each angular contact zone to correspond to contact points on one and/or the other of the two inclined planes SI ₁ and SI ₂ . In a general variant, only the teeth or the two pallets each have an inclined surface while respectively the two pallets or the teeth each have a projecting part configured so as to be able to slide at start-up along each of said inclined surfaces in the angular zones respective contacts. For the anchor, in the system of polar coordinates associated with it, the angular zones of contact at start-up, namely the zones of angular positions β(θ) on which there is contact at start-up, are given substantially by the curve 50 of angular positions of equilibrium β _ER (θ), previously defined, on the respective angular contact zones for the escape wheel ( Figure 2 ).

To the Figure 1D , one can see the low amplitude of a first alternation of the oscillation of the mechanical resonator 2 and the anchor 14 in one of its two rest positions. Then at the Figure 1E , while the pin 10 is again in the fork 18 of the anchor, a new mechanical impulse, applied to the anchor and transmitted to the balance of the mechanical resonator via the fork 18 and the pin 10 integral with the balance, is generated by a contact between the mechanical pallet 29 and a tooth 42. More precisely, the end of the tooth abuts against the inclined surface SI ₂ of the mechanical pallet 29 and possibly slides on a portion of this inclined surface, generating the mechanical impulse which complements a first magnetic starting pulse which is generated by the magnetic system of the escapement. A certain energy is thus transmitted again to the mechanical resonator 2 whose oscillation increases in amplitude while the escape wheel rotates a little faster. As a result, a tooth then comes into abutment against an abutment surface of the mechanical pallet 28 while the corresponding magnetic pallet has been able to entirely climb a ramp of magnetic potential energy 38, as shown in Figure 1F . From then on, the mechanical self-starting system can cease to be active and let the magnetic system of the escapement coupled to the balance wheel of the mechanical resonator generate pulses of magnetic force to maintain the oscillation of the mechanical resonator.

To the Figure 1G , we see the escapement supplying a first entirely magnetic sustaining pulse, no tooth coming into contact with the inclined surface of the mechanical pallet 28, given that the rocking of the anchor has become faster than during the previous alternation . The Figures 1H and 1I show the assembly formed by the mechanical resonator 2 and the escapement 12 in a short transitory phase before the appearance of a stationary operating phase corresponding to the normal operation of the watch movement whose mainspring has been reset.

Claims (11)

1. Horological movement comprising a mechanical resonator (2) and an escapement (12) which is associated with said mechanical resonator, the escapement comprising an escape wheel (16) having a first axis of rotation and a pallet assembly (14) separated from the mechanical resonator and having a second axis of rotation that is different from that of the mechanical resonator; the mechanical resonator being coupled to the pallet assembly in such a way that, when said mechanical resonator has an oscillation, the pallet assembly undergoes a reciprocating movement between two rest positions wherein the pallet assembly remains alternately during successive time intervals; the pallet assembly comprising at least one magnetic pallet-stone formed of a magnet (30, 32) and the escape wheel comprising a periodic magnetised structure (36) that defines a plurality of magnetic potential energy ascending ramps (38) for said magnetic pallet-stone, each of said magnetic potential energy ascending ramps being provided so that said magnetic pallet-stone can climb it when the pallet assembly is in a corresponding rest position from the two rest positions and when a force torque provided to the escape wheel is equal to the nominal force torque or in a range of values that is provided for a normal operation of the horological movement, said magnetic pallet-stone and the periodic magnetised structure being arranged in such a way that the pallet assembly undergoes a magnetic force impulse in the direction of the reciprocating movement thereof, after said magnetic pallet-stone has climbed any one of said magnetic potential energy ascending ramps, when the pallet assembly tilts from one of the two rest positions having enabled said magnetic pallet-stone to climb said any one of the magnetic potential energy ascending ramps to the other rest position;
   characterised in that the escape wheel comprises at least one first distant portion (42) relatively to said first axis of rotation and the pallet assembly comprises at least one second distant portion (28, 29) relatively to said second axis of rotation; in that, when the mechanical resonator is at rest, the pallet assembly has for any angular position θ of the escape wheel when stopped an equilibrium angular position β_ER (θ) that depends on said angular position; in that, for any angular position of at least one range of angular positions (PC_P1, PC_P2) of the escape wheel, the first and second distant portions are in contact with one another while the mechanical resonator is at rest and the pallet assembly is in the corresponding equilibrium angular position β_ER (θ), the first and second distant portions being arranged in such a way that the equilibrium angular position β_ER(θ) of the pallet assembly is, on at least one first portion of each range of angular positions from said at least one range of angular positions of the escape wheel, a monotonic function of the angular position θ of the escape wheel that moves away from a median position of the pallet assembly with a variation of said angular position θ in the direction of rotation provided for the escape wheel, said median position defining a zero angular position for the pallet assembly at equal angular distance from the two rest positions thereof; and in that a maximum absolute value (AM_E) of the equilibrium angular position β_ER(θ) of the pallet assembly on said at least one range of angular positions is strictly less than the absolute angular value (β_Max) of the two rest positions.
2. Horological movement according to claim 1, characterised in that the escape wheel (16) and the pallet assembly (14) are arranged in such a way that, when the escape wheel starts to rotate, in a starting phase, from any one of the angular positions θ by being subjected to a starting torque less than or equal to said force torque, it does not encounter any abutment of magnetic or mechanical origin that is likely to stop it before said escape wheel reaches a next range of angular positions, from said at least one range of angular positions (PC_P1, PC_P2), on at least one portion of which said at least one first distant portion and said at least one second distant portion are subsequently in contact; and in that said at least one first distant portion and said at least one second distant portion are configured so that, in said next range of angular positions, the escape wheel subjected to said starting torque is not stopped by the contact between the first and second distant portions concerned but that the first distant portion concerned may transmit at least mostly said starting torque to the pallet assembly.
3. Horological movement according to claim 1 or 2, characterised in that each first distant portion (42) from said at least one first distant portion has, in a polar coordinate system (R, θ) perpendicular to said first axis of rotation and centred thereon, a first inclined surface (SI₁) in such a way that each of said at least one second distant portion (28, 29) may slide on said first inclined surface while the escape wheel passes through a corresponding range of angular positions, from said at least one range of angular positions (PC_P1, PC_P2), and while the pallet assembly angularly follows a curve (50) defined by the corresponding equilibrium angular positions β_ER (θ).
4. Horological movement according to any one of the preceding claims, characterised in that each second distant portion (28, 29) from said at least one second distant portion has, in a polar coordinate system (R, θ) perpendicular to said first axis of rotation and centred thereon, a second inclined surface (SI₂) when the pallet assembly (14) is in any one of the equilibrium angular positions β_ER (θ) corresponding to any one of the angular positions of a range angular positions, from said at least one range of angular positions, wherein said second distant portion is in contact with a first distant portion from said at least one first distant portion (PC_P1, PC_P2), the second inclined surface being configured in such a way that each first distant portion (42) from said at least one first distant portion may slide on said second inclined surface while the escape wheel passes through a range of angular positions, from said at least one range of angular positions, which is relative to the first and second distant portions considered and while the pallet assembly angularly follows a curve (50) defined by the corresponding equilibrium angular positions β_ER (θ).
5. Horological movement according to any one of the preceding claims, wherein said magnetic pallet-stone is a first magnetic pallet-stone (30) and said second protruding portion is a first mechanical pallet-stone (28) that is associated with the first magnetic pallet-stone; characterised in that the pallet assembly comprises a second magnetic pallet-stone (32) and a second mechanical pallet-stone (29) associated with said second magnetic pallet-stone, said periodic magnetised structure (36) and the pallet assembly (14) being arranged in such a way that said plurality of magnetic potential energy ascending ramps (38) are also defined for the second magnetic pallet-stone, said ascending ramps being able to be climbed, when the force torque provided to the escape wheel is equal to said nominal force torque or in said range of values provided for the normal operation of the horological movement, successively by each of the first and second magnetic pallet-stones, when the pallet assembly is periodically in a first rest position, respectively in a second rest position from said two rest positions, and alternately by said first and second magnetic pallet-stones during the reciprocating movement of the pallet assembly; in that said second magnetic pallet-stone (32) and the plurality of magnetic potential energy ascending ramps are arranged in such a way that the pallet assembly (14) undergoes a magnetic force impulse in the direction of the movement thereof, after the second magnetic pallet-stone has climbed any one of said magnetic potential energy ascending ramps, when the pallet assembly tilts from the second rest position to the first rest position; and in that each ascending ramp of said plurality of magnetic potential energy ascending ramps is associated with a protruding portion different from a plurality of protruding portions (42) constituting said at least one first protruding portion.
6. Horological movement according to claim 5, characterised in that the first and second mechanical pallet-stones (28, 29) of the pallet assembly (14) define, in normal operation, two mechanical stops for said plurality of protruding portions; and in that the pallet assembly and the escape wheel are arranged in such a way that, when the pallet assembly has said reciprocating movement and said force torque provided to the escape wheel is equal to said nominal force torque or in at least one upper portion of said range of values and after the first or second magnetic pallet-stone has climbed any one of said magnetic potential energy ascending ramps following a tilting of the pallet assembly in the first or second corresponding rest position, the protruding portion (42) of the escape wheel (16) associated with said any one of said magnetic potential energy ascending ramps undergoes at least one first shock on said first or second mechanical pallet-stone of the pallet assembly, said first shock momentarily stopping the rotation of the escape wheel beyond an angular abutment position, defined by said first or second mechanical pallet-stone (28, 29), and occurring so as to dissipate at least partially a kinetic energy of the escape wheel acquired following said tilting.
7. Horological movement according to claim 6, characterised in that the escapement (12) is arranged in such a way that, following said first shock and before a next tilting of the pallet assembly (14), the escape wheel immobilises momentarily in an angular stop position.
8. Horological movement according to claim 7, characterised in that, when the force torque provided to the escape wheel is equal to the nominal force torque or has a value in at least one upper area of said upper portion of said range of values, said protruding portion (42) having undergone said at least one first shock, once the escape wheel momentarily immobile in said angular stop position, presses against said first or second mechanical pallet-stone, so that said angular stop position is then said angular abutment position.
9. Horological movement according to claim 7, characterised in that, for any force torque in said range of values, said at least one first shock is undergone by the protruding portion (42) of the escape wheel associated with said any one of said magnetic potential energy ascending ramps; and in that said protruding portion, once the escape wheel is momentarily stopped, presses against said first or second mechanical pallet-stone.
10. Horological movement according to any one of claims 5 to 9, characterised in that the periodic magnetised structure (36) is arranged so that the outer periphery thereof is substantially circular, arc of circle portions (38) of said magnetised structure, that define respectively said magnetic potential energy ramps, being circularly arranged about said first axis of rotation.
11. Horological movement according to any one of claims 5 to 10, characterised in that said protruding portions are formed by teeth (42) that extend in a general plane wherein also extend the first and second mechanical pallet-stones (28, 29) supporting respectively said magnet (30) and another magnet (32), forming the second magnetic pallet-stone, which are also located in the general plane.

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