Timepiece movement comprising an escapement provided with a toothed wheel and a retainer

Description

technical field

[0001] The invention relates to watch movements comprising an escapement equipped with a stop cooperating, on the one hand, with a toothed escape wheel and, on the other hand, with a mechanical resonator.

[0002] In particular, the invention relates to a watch movement equipped with an escapement comprising a magnetic coupling system between a toothed escape wheel and an anchor. As in the case of a Swiss lever escapement, the anchor exhibits an alternating motion that is synchronous with, but distinct from, the periodic motion of the mechanical resonator. This anchor is arranged to periodically stop the escape wheel, resulting in a step-by-step rotation synchronized with the mechanical resonator. The term 'magnetic escapement' refers to an escapement equipped with magnets arranged partly on the anchor and partly on the escape wheel to generate a magnetic coupling between the anchor and the escape wheel. Technological background

[0003] The Swiss lever escapement has been known for a very long time. In normal operation, the teeth of the escape wheel cooperate with two pallets of the anchor in a specific way, allowing the escape wheel to rotate stepwise in sync with the oscillation of the mechanical resonator, which is generally a balance wheel and hairspring. As the torque applied to the escape wheel decreases due to the mainspring unwinding, the sustaining impulses generated by the escapement and transmitted to the resonator gradually diminish in intensity. Therefore, when the escape wheel finally stops because the torque falls below a certain threshold, the energy stored in the resonator is relatively low.Thus, the risk of damage to a pallet or tooth of the escape wheel during a potential terminal impact between a pallet and a tooth, depending on the angular position at which the escape wheel stops, is relatively low, although not impossible. The situation is more problematic in the case of a watch movement equipped with a constant-force drive system for the escape wheel, because the resonator maintains essentially the same mechanical energy throughout the escapement's operation until the escape wheel and its drive come to a complete stop. The risk of an accidental event at the end of the watch movement's operation is therefore increased.

[0004] French patent application FR 1 047 551, particularly page 4, second and third paragraphs (complete on that page), and US patent application US 2 717 488, particularly lines 39 to 61 of column 4, describe a watch escapement comprising an escape wheel with teeth exhibiting elasticity in the tangential direction but good rigidity in the radial direction, in order to dampen the tangential shocks occurring between the teeth of the escape wheel and the two pallets of the anchor during normal operation of the escapement. To reduce the variation in the impulses supplied to the anchor by the escape wheel, patent application EP 2 801 868 A2 proposes an escape wheel with teeth mounted on radially oriented flexible blades, such that these blades can easily deform under the action of a tangential force.Stops formed by the configuration of the escape wheel in the general plane of the teeth are provided to limit such tangential deformation and also rotation of the teeth. Summary of the invention

[0005] During the development process leading to the invention, it was observed that the problem described above becomes a major drawback in the case of a watch movement incorporating a hybrid magnetic and mechanical escapement. Specifically, it was found that the risk of a terminal collision between the anchor and the escape wheel increases significantly in the case of a hybrid escapement, namely an escapement equipped with a magnetic coupling system between the anchor and the escape wheel, with magnetic potential energy ramps that allow the accumulation of magnetic potential energy in the escapement at each step of the escape wheel's rotation before generating a magnetic pulse at the end of the step, while the escape wheel is at rest.The escape wheel of the hybrid escapement includes projecting parts designed to cooperate with mechanical pallets of the anchor in at least one phase of the escapement's operation (for example, at startup and, more specifically, during the normal operation of the watch movement, to absorb kinetic energy at each step of the escape wheel and define angular stopping positions for the escape wheel, as will be explained in the detailed description of the invention). Indeed, the hybrid escapement presents the risk of the escape wheel stopping in an unfavorable angular position while the mechanical resonator still possesses nominal mechanical energy. Firstly, the maintenance pulses are magnetic pulses with a constant value as long as the torque applied to the escape wheel is greater than or equal to a certain lower limit.Then, as soon as the torque falls below this lower limit, the escape wheel can no longer properly ascend the next magnetic potential energy ramp, so the escape wheel will not stop in its normal next angular position, but substantially at the bottom of or along a magnetic potential energy ramp. Therefore, since the mechanical resonator normally oscillates during such an event because it has previously received magnetic pulses of substantially constant intensity (nominal intensity), if a mechanical pallet is positioned opposite a tooth during the next pivoting of the anchor, a significant shock can occur and damage the escape wheel or the anchor, or even the mechanical resonator. This increased technical problem thus requires a suitable technical solution.

[0006] To this end, the invention relates to a watch movement comprising a mechanical resonator and an escapement associated with this mechanical resonator. The escapement comprises an escape wheel, provided with a plurality of projecting parts, and a stop comprising two mechanical pallets, forming two mechanical stops for the plurality of projecting parts, and a fork arranged to cooperate with the mechanical resonator via the periodic engagement of a pin, integral with this mechanical resonator, between two lugs of the fork. The mechanical resonator is coupled to the stop such that, during normal operation of the watch movement, the stop undergoes an alternating movement between two rest positions in which it remains alternately for successive time intervals.The escapement is arranged so as to allow, during the normal operation of the watch movement, an absorption of kinetic energy of the escape wheel by successive shocks, between the plurality of salient parts and alternately the two mechanical pallets, respectively at the end of successive steps of a step-by-step rotation of the escape wheel.According to the invention, the escapement is arranged so that, when the stop is tilted from one of its two rest positions towards the second rest position, while the escape wheel has any angular position in a plurality of angular position ranges corresponding respectively to the plurality of salient parts, one of the two mechanical pallets abuts against a salient part corresponding to the range of angular positions concerned before the stop can reach an angular position of release of the pin on the side of the second rest position, said one of the two mechanical pallets then exerting on said salient part a radial force, relative to the axis of rotation of the escape wheel, the intensity of which is a function of said any angular position of the escape wheel.Next, the protruding parts of the escape wheel are flexible and each is arranged so as to be able to flex, in a general plane perpendicular to an axis of rotation of the stop, undergoing a radial elastic deformation under the action of said radial force, each protruding part having an elastic capacity enabling it to elastically absorb, during said elastic deformation, most of the maximum mechanical energy that the mechanical resonator can have during the normal operation of the watch movement.

[0007] In the general embodiment described above, the flexible protruding parts are configured and the elasticity coefficients of these flexible protruding parts are selected so as to allow good elastic absorption of the mechanical energy of the mechanical resonator in the case of a stop of the escape wheel in an angular position of the range of angular positions corresponding to the protruding part concerned, while the mechanical resonator oscillates with an amplitude corresponding to a normal operation of the watch movement, and so as to allow good non-elastic absorption of the kinetic energy of the escape wheel at the end of each step of its step-by-step rotation during a normal operation.It should be noted that it is possible to have these two properties of different natures, primarily for two main reasons, thanks to a judicious configuration of the projecting parts and the choice of elasticity coefficients / elastic deformation capacities, in the radial and angular directions, appropriate to the two functions that the flexible projecting parts must perform. Firstly, the mechanical energy of the mechanical resonator in normal operation is much greater than the kinetic energy of the escape wheel at the end of each of its steps during its step-by-step rotation. The energy ranges involved in these two cases are not of the same order of magnitude.Next, the impact between a mechanical pallet and a protruding part generates, in normal operation, on this protruding part a tangential force, relative to the axis of rotation of the escape wheel, whereas the impact between a mechanical pallet and this protruding part, during a stop of the escape wheel in the range of angular positions corresponding to the protruding part considered, generates on this protruding part generally a force mainly radial.

[0008] In a preferred embodiment of the invention, a plurality of rigid parts, fixed to the escape wheel, are arranged respectively behind the plurality of flexible projecting parts, relative to the normal direction of the step-by-step rotation of the escape wheel, such that each flexible projecting part is held by the corresponding rigid part during an impact, among the successive impacts mentioned above, occurring between this projecting part and one or the other of the two mechanical pallets, to prevent or limit a recoil of this flexible projecting part during this impact and to allow the dissipation of most of the kinetic energy possessed by the escape wheel at the beginning of this impact. By 'recoil of a projecting part', we understand an angular displacement of the projecting part in the direction opposite to that of the normal rotation of the escape wheel.Next, the arrangement of the plurality of rigid parts is provided so that, when a mechanical paddle hits a flexible protruding part and the mechanical resonator is then braked by the stop, each flexible protruding part subjected to the radial force mentioned above can deform elastically so as to elastically absorb most of the work of this radial force.

[0009] In a particular embodiment, the escapement or a drive mechanism for the escape wheel is arranged so that, during normal operation of the clock movement, the escape wheel provides the stopper with maintenance impulses of an oscillation of the mechanical resonator which have substantially constant energy as long as the clock movement operates normally.

[0010] In a principal embodiment, the escapement includes a magnetic system magnetically coupling the escape wheel and the stop, this magnetic system being arranged to generate, during the normal operation of the watch movement, magnetic pulses which form the aforementioned constant energy maintenance pulses.

[0011] In an advantageous embodiment, the stop also possesses an elastic capacity enabling it to elastically absorb, when one of the two mechanical pallets strikes a protruding part while the escape wheel is in an angular position within the corresponding range of angular positions and the mechanical resonator is slowed by the stop, a portion of the mechanical energy possessed by the mechanical resonator at the beginning of such an event. In this case, the anchor and the relevant protruding part together advantageously possess an elastic capacity enabling them to elastically absorb, during said event, the maximum mechanical energy that the mechanical resonator can possess during the normal operation of the watch movement. Brief description of the figures

[0012] The invention will be described in more detail below with reference to the accompanying drawings, given by way of non-limiting examples, in which: THE Figures 1A to 1D show, for a mechanical watch movement according to a preferred embodiment of the invention, a succession of snapshots of the mechanical resonator and the escapement during normal operation of the watch movement; The Figures 2A and 2B show a start-up phase of the watch movement, represented in the preceding figures, during which the escapement and the mechanical resonator are activated; The Figures 3A to 3F show a succession of snapshots of the mechanical resonator and the escapement during a stop-start phase of the clockwork movement, shown in the previous figures, following a stop of the escape wheel in an unfavorable angular position. Detailed description of the invention

[0013] With the aid of the accompanying figures, a preferred embodiment of a clock movement according to the invention will be described below. This movement is of the mechanical type and comprises a mechanical resonator 2, of which only the axle 4, the small plate 6 with a notch, and the pin 10 are shown. The clock movement includes an escapement 12 associated with the mechanical resonator, the small plate and the pin being elements forming this escapement. The escapement 12 further comprises an escape wheel 16 and a pallet fork 14 with an axle 15 defining its axis of rotation.

[0014] The anchor 14 is formed, on the one hand, of a fork 18, comprising two horns 19a and 19b, and a dart 8 and, on the other hand, of two arms 24 and 26 whose free ends form respectively two mechanical paddles 28 and 29. A connecting part 25 links the fork 18 to the arm 26 which is located on the side of the axis 4 of the mechanical resonator 2 relative to the axis 15 of the anchor. 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 mechanical resonator 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 for successive time intervals.

[0015] The escape wheel 16 comprises a periodic magnetized structure 36 arranged on a disk 34, preferably made of a non-magnetic material (not conducting magnetic fields so as not to make the escape wheel sensitive to external magnetic fields that could exert a significant torque on it if the disk were made of a ferromagnetic material). The structure 36 has magnetized portions 38, generally in the shape of an arc, which define increasing ramps of magnetic potential energy for the two magnetic vanes 30 and 32. Each vane has an axial magnetization with a polarity opposite to that of the axial magnetization of the periodic magnetized structure 36, so as to generate magnetic repulsion between the magnetic vanes and the magnetized structure. Each magnetized portion has a monotonically increasing width.In particular, the width of the magnetized portions 38 increases linearly along their entire effective length as a function of the central angle. According to an advantageous variant, the periodic magnetized structure 36 is arranged so that its outer perimeter is circular, the arc-shaped magnetized portions of this magnetized structure having the same configuration and being arranged circularly around the axis of rotation of the escape wheel 16.

[0016] 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 nominal torque of force (case of a mechanical movement equipped with a constant force system for driving the escape wheel) or within a range of values ​​provided to ensure the normal operation of the watch movement (case of a classic mechanical movement with a variable torque of force applied to the escape wheel depending on the winding level of the barrel or barrels).The increasing ramps of magnetic potential energy are climbed, when the anchor undergoes an alternating motion between its two rest positions and when the torque supplied to the escape wheel is equal to said nominal torque or within the range of values ​​expected for this torque in normal operation, successively by each of the first and second magnetic pallets while the anchor is periodically and respectively in its first and second rest positions, and alternately by these first and second magnetic pallets during the alternating motion of the anchor.The two magnetic paddles and the increasing ramps of magnetic potential energy are arranged so that the anchor can receive a magnetic force impulse in the direction of its movement, after one or the other of the two magnetic paddles has climbed any of said increasing ramps of magnetic potential energy, when the anchor swings from the rest position corresponding to a magnetic coupling between the magnetic paddle concerned and said any ramp of magnetic potential energy to its other rest position.

[0017] The escape wheel further comprises projecting parts 42 which are associated respectively with the magnetized portions 38 and thus with the increasing ramps of magnetic potential energy. In the embodiment shown, these projecting parts are formed by flexible teeth 42 extending around the periphery of a plate 40 with which the teeth are formed from a single piece of material. This plate is integral with the escape wheel and located above the disk 34 which carries the magnetized structure 36. The heads of the flexible teeth are located at the wider end of the magnetized portions 38 and are partially superimposed on these magnetized portions. The flexible teeth and the mechanical vanes are formed from a non-magnetic material. Preferably, the plate 40 is also formed from a non-magnetic material and is formed from a single piece of material with the teeth.

[0018] In the advantageous variant shown, the teeth 42 extend in a general plane in which the two mechanical pallets 28, 29 of the anchor also extend. The two magnets 30, 32 are supported respectively by the two mechanical pallets and are also located in this general plane. The figures show only a lower magnetized structure, situated below the general plane. However, in an advantageous variant, the escape wheel further comprises an upper magnetized structure, with the same configuration as the lower magnetized structure and supported by an upper disk, preferably made of a non-magnetic material. The lower and upper magnetized structures together form the periodic magnetized 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 paddles are located, preferably at the same distance.

[0019] The escapement 12 is a hybrid type, that is, magnetic and mechanical, which improves the behavior of a magnetic escapement during normal operation (i.e., during stable operation, occurring after a start-up phase, with a torque M RE applied to the escape wheel that is substantially equal to a nominal torque or within a range of values ​​P VM designed to ensure the normal operation of the watch movement, in particular the correct step-by-step rotation of the escape wheel). Furthermore, the escapement 12 enables the assembly formed by the escapement and the mechanical resonator to start automatically. The role of the teeth 42 of the escapement 12 during the normal operation of the watch movement will be explained later, particularly with the help of the Figures 1A to 1C , and then the self-start phase will be exposed using the Figures 2A and 2B .

[0020] In general, the escapement 12 is arranged so as to allow, during normal operation of the watch movement, the absorption of kinetic energy from the escape wheel by successive impacts between the plurality of protruding parts 42 and alternately the two mechanical pallets 28, 29, respectively at the end of successive steps of a step-by-step rotation of the escape wheel. The anchor 14 and the escape wheel 16 are arranged so that, during normal operation, one of the teeth 42 of the escape wheel receives at least one impact on one or the other of the two mechanical pallets after the corresponding magnetic pallet has 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 dissipate at least partially the kinetic energy of the escape wheel acquired following said tilting.The teeth of the escape wheel are therefore designed so that, during the normal operation of the watch movement, they can absorb kinetic energy from this escape wheel, at each step of the escape wheel, in a non-elastic manner, after an accumulation of magnetic potential energy in the escapement intended for a future magnetic pulse to maintain the mechanical resonator, and thus limit or even prevent a terminal oscillation of the escape wheel, thanks to the strong damping provided, at each step of its step-by-step rotation.

[0021] In the preferred variant described, during normal operation and once the escape wheel has momentarily stopped, a flexible tooth 42 presses against a mechanical stop / anchor stop surface formed by one or the other of the two mechanical pallets. Thus, for a conventional watch movement, it is envisaged that, during normal operation and for the entire range of values ​​PVM of the torque MRE, the escape wheel will momentarily stop, after at least one initial impact of any one of its teeth against any one of the two mechanical pallets 28, 29 and before a subsequent pivoting of the anchor, at a stopping angular position in which the tooth presses against the mechanical pallet. Each stopping angular position is thus defined by a tooth bearing against a mechanical pallet, as shown in the Figure 1A .

[0022] For the function of the flexible teeth 42 to be performed effectively under normal operating conditions, it is important that these teeth exhibit relatively high rigidity during tangential impacts of their respective heads against the mechanical pallets while the escape wheel is driven step-by-step in its normal direction of rotation. Therefore, the desired rigidity is expected to manifest itself under a relatively large tangential force exerted by a mechanical pallet on the head of any flexible tooth, in the opposite direction to the normal rotation of the escape wheel.To this end, a plurality of rigid parts, formed in particular by pins 44 fixed to the disc 34 and rising from it in the direction of a general plane in which the flexible teeth 42 extend, are arranged respectively at the rear of the plurality of flexible teeth, so as to neutralize or inhibit in large part the flexibility of these teeth during the successive shocks, provided for in normal operation, to absorb kinetic energy of the escape wheel at the end of each step of its step-by-step rotation and to limit, or even prevent, an oscillation of the escape wheel following an accumulation of magnetic potential energy preceding a first shock between a mechanical pallet and a tooth at the end of each step.

[0023] In general, the plurality of rigid parts (retaining pins 44), attached to the escape wheel 16, are arranged respectively behind the plurality of flexible protruding parts (flexible teeth 42), relative to the normal direction of step-by-step rotation of the escape wheel.The configuration of the flexible teeth 42 and the retaining pins 44 is designed so that each pin substantially blocks any movement of the corresponding tooth in a tangential direction and in the opposite direction to that of the normal rotation of the escape wheel, so that each flexible tooth 42 is retained by the corresponding pin during a shock occurring, in normal operation, between this flexible tooth and one or the other of the two mechanical pallets of the anchor, to prevent or strongly limit a recoil of this flexible tooth during this shock and to allow a dissipation of the major part of the kinetic energy which the escape wheel possesses at the beginning of this shock.

[0024] In the specific variant shown in the figures, the flexible teeth 42 have a particular configuration with a head 42a, the tip of which, in normal operation, abuts against one and subsequently the other of the two mechanical pallets of the anchor, a rigid or semi-rigid body 42b, and an end portion 42c formed by a flexible blade oriented primarily tangentially to the center of the escape wheel, more specifically substantially parallel to the tangential direction at the tip of the tip of the flexible tooth in question. This tip defines the point of contact with each mechanical pallet during the normal operation of the watch movement. The end portion of each tooth is fixed to a base 43 projecting from the plate 40 and having an orientation substantially perpendicular to this end portion. The base is rigid or semi-rigid, depending on the variant.By 'semi-rigid', we understand a rigidity much greater than that of the flexible blade along its transverse direction in the general plane of the flexible tooth, and therefore a lesser elasticity without having a rigidity that practically excludes any elastic deformation during an impact.

[0025] It should be noted that the configuration of the flexible teeth 42 provided in the aforementioned specific variant is also advantageous and suitable for the general embodiment described earlier in the summary of the invention. Indeed, the flexible teeth exhibit relatively high elasticity in the radial direction at the apex of their head (in the case of a frontal impact between a pallet and the apex of a tooth head when the watch movement stops functioning normally, a situation which will be described in more detail later with reference to the Figures 3A to 3F), but a relatively small elasticity along the tangential direction at the end of their nose (for non-elastic absorption of kinetic energy of the escape wheel during the successive impacts expected with the mechanical pallets during the normal operation of the watch movement), because the terminal part 42c is at least semi-rigid along the longitudinal direction of the flexible blade which forms this terminal part.However, as the nose of each tooth is radially distant from the terminal part of that tooth, a tangential shock at the nose of a tooth generates a certain torque on the tooth relative to the anchoring point of its terminal part at the base 43, in the opposite direction to that of the rotation of the escape wheel, given that the normal to the point of shock on the contact surface of each mechanical pallet passes largely above the terminal part, in a polar coordinate system centered on the escape wheel, so that the terminal part 42c then reacts as an elastic joint, in particular in rotation around its anchoring point at the base 43, and the head of the tooth can undergo a recoil movement, with an elastic deformation of the terminal part, which is a disadvantage remaining in the general embodiment for the normal operation of the watch movement.The preferred embodiment described with reference to the figures solves this specific problem and allows for optimization of the operation of the hybrid exhaust.

[0026] In the preferred embodiment, in the variant shown in the figures, retaining pins 44 are arranged behind the bodies 42b of the flexible teeth, a short distance from these tooth bodies or bearing against them. Since the elasticity of each flexible tooth is mainly integrated into its terminal portion 42c and since the flexible blade forming it is intended to be oriented mainly tangentially with respect to the point of contact between the flexible tooth and the retaining pin, this tooth exhibits, as desired, relatively high rigidity during an impact between its tip and either of the two mechanical paddles in normal operation (as shown, the flexible blade forming the terminal portion of the tooth exhibits relatively high elasticity in the direction transverse to this blade, but relatively high rigidity in its longitudinal direction).Each retaining pin 44 has at least two functions in normal operation of the watch movement, namely a first function consisting of blocking the elastic joint formed by the flexible terminal part 42c of the corresponding flexible tooth in order to obtain a relatively high rigidity of this tooth during a tangential shock at the end of said nose of its head, the second function being to participate in a non-elastic absorption of the kinetic energy of the escape wheel during such a tangential shock.

[0027] THE Figures 1A to 1D show four snapshots of the assembly formed by the mechanical resonator 2 and the hybrid escapement 12 during normal operation of the watch movement incorporating this assembly. At the Figure 1AWhile the mechanical resonator 2 oscillates within its free angular range, i.e., without interaction with the fork 18 of the anchor 12, the latter is in one of its two rest positions, bearing against the limiting pin 22. Next, the escape wheel 16 is in an end-of-pitch angular position in which it is stopped by the mechanical pallet 28 against which the nose of the head 42a of a flexible tooth 42 abuts. The body 42b of this flexible tooth is held by a pin 44 arranged upstream of the tooth, i.e., behind the body 42b. The flexible tooth undergoes virtually no elastic deformation in this situation. Figure 1Brepresents the aforementioned assembly when the mechanical resonator pin 10 is engaged in the fork / inserted between the two horns 19a and 19b thereof, just after the pin has angularly displaced the anchor 14 a little so as to move the magnet 30 sufficiently in a radial direction to allow this anchor to pivot between its two rest positions by generating a magnetic impulse which then generates a torque on the anchor, which becomes a driver of the mechanical resonator 2, as shown, and provides it with a maintenance impulse without requiring at this event an angular displacement of the escape wheel.

[0028] There Figure 1Crepresents the assembly under consideration when the tilting of the anchor 14 has ended and the mechanical resonator has again freed itself from the anchor, which is now in its second rest position. The magnet 32 ​​associated with the mechanical pallet 29 begins to climb a magnetic potential energy ramp formed by a magnetized portion 38, defining an increasing ramp for the magnet 32, while the escape wheel is driven in rotation by the motor of the clockwork movement. At the Figure 1DA tangential impact is shown occurring between a flexible tooth 42 and the mechanical pallet 29 when the magnet 32 ​​reaches the top of the intended magnetic potential energy ramp. This tangential impact and the reaction of the assembly formed by the tooth 42 and its associated retaining pin 44 have been described in detail previously. As a result of the arrangement of this assembly, the flexible tooth 42 remains essentially rigid during such an impact and undergoes almost no elastic deformation, while the escape wheel, particularly via the pin 44, and the anchor 14 absorb most of the kinetic energy possessed by the escape wheel during the tangential impact.

[0029] Next, the flexible teeth 42 and the mechanical pallets 28, 29 are arranged so that, when the mainspring is rewound following a stop of the watch movement, allowing the escape wheel 16 to resume rotation in its intended direction, at least one of the two mechanical pallets 28, 29 comes into contact with a tooth 42 of the escape wheel. These pallets are configured so that the escape wheel can provide the anchor 14 with a starting mechanical torque and thus a starting mechanical impulse. This enables efficient and rapid self-starting of the assembly formed by the escapement 12 and the mechanical resonator 2, and therefore of the mechanical watch movement.The escape wheel subjected to said starting torque is not stopped by the contact between the flexible tooth and the mechanical pallet concerned, and the flexible tooth is arranged in association with the retaining pin 44 so as to be able to transmit at least part of said starting torque to the anchor.

[0030] In the variant shown in the figures, each of the flexible teeth 42 has, in a polar coordinate system centered on the axis of rotation of the escape wheel 16, a first inclined surface SI1. This surface is inclined such that each of the first and second mechanical pallets 28, 29 can, during a starting phase, slide on this first inclined surface as the escape wheel traverses a corresponding range of angular positions θ. In a polar coordinate system, 'inclined surface' is understood to mean a surface that is neither radial nor tangential. Furthermore, each of the two mechanical pallets of the anchor has, in the polar coordinate system associated with the escape wheel, a second inclined surface SI2 when the pallet in question is in contact with one of the teeth 42 of the escape wheel.The second inclined surface is configured so that each of the teeth 42 can, in a starting phase, slide on this second inclined surface when the escape wheel crosses a range of angular positions θ which corresponds to a contact area between the tooth and the mechanical pallet considered.

[0031] For the starting phase, it is sufficient that an oscillation of the mechanical resonator be activated, thereby triggering the alternating movement of the anchor, which is then maintained by magnetic pulses. Thus, the fact that the flexible teeth may exhibit some elastic deformation in a radial direction is not a determining factor for the starting function, although this could reduce the efficiency of the intended starting system.To limit radial elastic deformation of the flexible tooth towards the center of the escape wheel, the flexible teeth, retaining pins, and mechanical vanes are arranged so that the reaction force exerted at startup by a mechanical vane in contact with a flexible tooth, as the escape wheel begins to rotate, has an overall orientation that, in the polar coordinate system of the escape wheel, passes over the point of contact between the body 42b of the tooth in question and the retaining pin located behind this tooth body. In particular, depending on the inclination of the inclined surface of the mechanical vane when a head 42a of a flexible tooth presses against it, a certain frictional force between this head and the inclined surface can be beneficial.However, this friction force must not be too great to allow the tooth to slide along this inclined surface to generate a starting impulse.

[0032] There Figure 2A shows the assembly formed by the escape wheel 16, the anchor 14, and the mechanical resonator 2, initially at rest, at the beginning of a starting impulse. The horn 19b of the fork 18 begins to exert a starting force on the pin 10 of the mechanical resonator. Subsequently, the escape wheel continues to rotate, and the anchor experiences a mechanical torque that is transmitted to the mechanical resonator via the coupling between the fork and the pin until a situation such as that shown in the Figure 2B in which the mechanical resonator has received a starting mechanical impulse, possibly reinforced by some simultaneous magnetic impulse; which initiates an oscillation of this mechanical resonator.

[0033] The incorporation of teeth 42 to enable one or the other of the two functions described above, namely the damping of oscillations of the escape wheel during its step-by-step rotation in normal operation and a self-starting of the assembly formed by the mechanical resonator and the escapement, in particular a magnetic escapement, results in the following: when the anchor 14 is tilted from one of its two rest positions towards the second rest position while the escape wheel 16 is positioned in any angular position θ within a plurality of angular position ranges corresponding respectively to the plurality of teeth, one of the two mechanical pallets abuts against one of these teeth before the anchor can reach the angular position of the pin disengagement on the side of the second rest position, as shown in the Figure 3BThe 'angular clearance position' for the pin of a mechanical resonator, particularly a balance spring, refers to the angular position (on either side of a median position defining a zero angular position for the anchor) from which the pin can disengage, for one reason or another, from the fork; that is, exit the cavity formed by the two horns 19a and 19b without striking either of these horns. This clearance position occurs before the anchor reaches either of its two resting positions. It should be noted that this latter point results from a standard safety angle designed to ensure that the pin can properly exit the fork without experiencing a shock or terminal friction that would cause it to lose energy with each oscillation and disrupt the oscillation of the mechanical resonator.

[0034] When the mainspring unwinds, there comes a point where the watch movement ceases to function normally because the torque the mainspring can supply to the gear train and escape wheel becomes insufficient to ensure such normal operation. At a certain instant, as shown in the Figure 3AThe escape wheel 16 finally stops rotating and comes to rest in a certain angular position θ, but the mechanical resonator 2 is still oscillating at that instant and may even possess a substantially nominal and therefore relatively significant mechanical energy, as is generally the case with an escapement 12 equipped with the magnetic system described previously. As mentioned in the preceding paragraph, particularly in the case of an escapement 12 equipped with the magnetic system to provide magnetic maintenance pulses, the escape wheel can stop in any angular position θ within a plurality of angular position ranges, corresponding respectively to the plurality of flexible teeth 42, for which one of the two mechanical pallets then abuts against one of these teeth before the anchor can reach the pin release angular position, as shown in the Figure 3B . This Figure 3BThis shows a particularly unfavorable case where an end portion of the mechanical pallet 29 is struck against the top of the head 42a of a flexible tooth 42 against which this mechanical pallet abuts. In such a case, the substantially radial force, in a polar coordinate system associated with the escape wheel, exerted by the anchor's mechanical pallet on the flexible tooth in question is substantially perpendicular to the contact surface of the head 42a, and the normal reaction force of the tooth is then substantially equal in magnitude to the radial force, so that this tooth and the mechanical pallet undergo a frontal impact.

[0035] It should be noted that the frontal impact, with a substantially radial direction, does not only concern the instant at which the mechanical paddle and the tooth come into contact, but is a radial force impulse that has a certain duration, given that this frontal impact occurs while the pin of the oscillating resonator is inserted between the two horns 19a and 19b of the fork 18 and a magnetic impulse is supplied to the anchor. During the aforementioned impact, the radial force impulse has several components: Firstly, a component arising from the inertia of the moving anchor 14, which is stopped; secondly, a main component due to the mechanical energy stored in the oscillating mechanical resonator 2, which is stopped in its oscillation while its kinetic energy is almost at its maximum, via the coupling between the fork 18 and the pin 10; thirdly, a magnetic component arising from the fact that the impact occurs while a magnetic impulse is supplied to the anchor. Thus, it is probable that, when the end part of the mechanical pallet 29 comes into contact with the head 42a of a tooth, butting against the top of this head, it is the anchor 14 that drives the mechanical resonator 2 by its horn 19b, which is bearing against the pin 10, and only then, after a very short time interval, does this pin come to rest against the horn 19a of the fork, as shown in the Figure 3B, and then undergoes a strong deceleration due to the premature stopping of the anchor during its tilting motion.

[0036] The more violent the braking of the mechanical resonator during the aforementioned shock, the greater the force exerted orthogonally on the horn 19a by the mechanical resonator, and by construction substantially tangentially in a polar coordinate system associated with the anchor, and the reaction force of the anchor that brakes this mechanical resonator at the beginning of the shock. This poses a major problem, which is why the escape wheel 16 is arranged and configured to prevent breakage or damage to any of its parts, the anchor, or even a part of the mechanical resonator during an event such as that shown in the diagrams. Figures 3B and 3CTo reduce the intensity of the force exerted by the resonator's ankle during said significant shock and thus avoid an excessively strong instantaneous stress, a relatively long shock duration is planned with an elastic absorption of kinetic energy of the mechanical resonator 2 allowing the latter to decelerate over a certain angular distance and thus reduce the intensity of the deceleration.

[0037] To this end, the teeth 42 of the escape wheel 16 are flexible, and each is arranged so as to be able to flex, in a plane generally perpendicular to an axis of rotation of the anchor 14, by undergoing elastic deformation under the action of a radial force, relative to the axis of rotation of the escape wheel. This force is exerted by one of the two mechanical pallets bearing against the flexible tooth in question, while the escape wheel is at any angular position within a corresponding range of angular positions, mentioned previously, and the mechanical resonator is braked by the anchor. Each flexible tooth has an elastic capacity enabling it to elastically absorb, during said elastic deformation under the action of said radial force, most of the maximum mechanical energy that the mechanical resonator can possess during the normal operation of the watch movement.It will be noted that, during the impact between the mechanical pallet and the flexible tooth, there is a certain dissipation of energy, particularly in the mechanical resonator and the anchor, and also in other relevant structures, notably in the plate 40 and the escape wheel bearings. Thanks to the invention, any breakage or damage to the escapement and the mechanical resonator can thus be avoided. It has already been explained that the flexible teeth 42 have been configured so as to exhibit primarily elasticity along a radial direction passing through the apex of their head 42a. Indeed, the terminal portion 42c of each tooth exhibiting the greatest flexibility, and consequently the greatest elastic capacity, is formed by a flexible blade that is oriented primarily orthogonally to this radial direction.

[0038] By "flexible tooth", we generally understand a protruding element of which at least a part and / or a part of the connection of this element to a support can deform elastically during a shock, in particular substantially radial, which this element may undergo under the action of a mechanical pallet of the anchor, by presenting a sufficient elastic capacity to elastically absorb a significant part of the mechanical energy of the mechanical resonator which the anchor can transmit to this element when the mechanical resonator, initially having a mechanical energy corresponding to a normal operation of the watch movement, is close to its rest position and suddenly braked, in particular to a zero speed, by the anchor whose mechanical pallet abuts against the protruding element.By 'elastic capacity', we mean the capacity to absorb elastic energy, elastic energy being the energy stored in a constrained material in the form of elastic deformation. Thanks to the characteristics of the escape wheel according to the invention, an excessively abrupt impact between the wheel and the anchor is avoided, and the mechanical energy of the mechanical resonator is dissipated gradually when the escape wheel stops, regardless of its angular position.

[0039] To the Figure 3CIt is observed that, during the elastic deformation of a flexible tooth 42 under the action of a radial force due to a frontal impact of a substantially radial direction, the tooth experiences a significant torque in the direction of the normal rotation of the escape wheel, and it undergoes a certain rotation towards the center of the escape wheel as the terminal portion 42c flexes until the tooth abuts against the periphery of the plate 40 and / or the base 43 of the tooth located in front of it. The deflection of the tooth is therefore limited by a corresponding stop included in the escape wheel. It is also observed that the pin 44 associated with the tooth subjected to said radial force is arranged so that the body 42b of this tooth moves away from this pin during the deflection of the tooth.In general, the plurality of rigid parts (namely the pins 44 in the variant shown) is arranged so as to allow that, when a mechanical paddle butts against a flexible protruding part (namely a flexible tooth 42 in the variant shown) and the mechanical resonator 2 is then braked by the anchor 14, the flexible protruding part subjected to said radial force can deform elastically so as to elastically absorb most of the work of this radial force.The rigid parts serving as retaining elements for the flexible teeth, and located in particular behind the bodies of these flexible teeth, do not in any way hinder the elastic absorption function of the majority of the mechanical energy of the mechanical resonator during a frontal impact of substantially radial direction between a flexible tooth 42 and a mechanical pallet of the anchor 14 which can occur when the escape wheel stops turning step-by-step and the mechanical movement stops functioning normally.

[0040] In the case of a frontal impact of substantially radial direction between the mechanical paddle 29 and a flexible tooth 42 shown in Figures 3A to 3F , the mechanical resonator 2 undergoes such deceleration that it eventually comes to a stop approximately in the position shown in the Figure 3C , before a release of the ankle 10 of the fork 18. At 3D to 3F FiguresA possible evolution of the behavior of the hybrid escapement and the mechanical resonator is shown, up to a complete stop of these mechanisms. Once the mechanical resonator 2 has stopped, the flexible tooth, elastically deformed by the mechanical paddle 29, returns energy absorbed elastically to the mechanical resonator via the anchor, which thus provides a certain force impulse to this resonator until the flexible tooth 42 comes to rest against the pin 44, this event being represented in the 3D FigurePin 44 plays an important role in this phase because, once the frontal impact is complete (the frontal impact in question lasts as long as the radial force, mentioned previously, exerted on the relevant flexible tooth is generated by the deceleration of the mechanical resonator), it allows for the dissipation of some of the elastic energy absorbed during the frontal impact and thus reduces the amount of mechanical energy returned to the mechanical resonator, so as to quickly dampen any residual oscillation until the mechanical resonator comes to a complete stop. Figure 3EThis shows a snapshot with the mechanical resonator in an extreme angular position defining the amplitude of an alternation generated by the partial restitution of the elastic energy absorbed by the flexible tooth. It should be noted that the escape wheel may undergo a slight rotation, particularly forward, during the frontal impact and also during the tooth's return towards the retaining pin 44. Figure 3F shows a probable final position for the mechanical resonator and the escapement at rest, with a mechanical pallet resting against an inclined surface of one of the flexible teeth.

[0041] In an advantageous embodiment, the flexible teeth 42 are arranged to bear against the retaining pins 44 with a preload, that is, with a certain initial elastic deformation induced by the retaining pins on the respective teeth in the absence of other forces. Such a preload increases the elastic absorption capacity of the flexible teeth over a given displacement distance from an initial position, abutting the respective pins, to a final position where these teeth abut against a base 43 of a downstream tooth and / or against the periphery of the plate 40 which supports the flexible teeth at its periphery, as in the embodiment shown in the figures.

Claims

1. A horology movement comprising a mechanical resonator (2), an escapement (12) that is associated with this mechanical resonator and that comprises an escape wheel (16) having a plurality of protruding parts (42), and a stop (14), this stop comprising two mechanical pallet stones (28, 29) respectively forming two mechanical stops for the plurality of protruding parts, and a fork (18) arranged to engage with the mechanical resonator via a periodic engagement of a pin (10) attached to this mechanical resonator between two horns (19a, 19b) of the fork, the mechanical resonator being coupled to the stop so that, when the horology movement is functioning normally, the stop undergoes an alternating movement between two lock positions in which this stop alternately remains for successive time intervals; in which the escapement is arranged so as to allow, when the horology movement is functioning normally, absorption of kinetic energy from the escape wheel by successive shocks between the plurality of protruding parts (42) and alternately the two mechanical pallet stones (28, 29), respectively at the end of successive steps in a stepping rotation of the escape wheel; in which the escape wheel has a plurality of ranges of angular positions corresponding respectively to the plurality of protruding parts, in which, when the stop (14) is levered from one of its two lock positions towards the second lock position, one of the two mechanical pallet stones comes up against one of the protruding parts before the stop can reach an angular position in which the pin (10) is released on the side of the second lock position, then exerting on said protruding part a radial force relative to an axis of rotation of the escape wheel, each range of angular positions comprising an angular position at which a substantially radial frontal shock occurs between the corresponding protruding part and the mechanical pallet stone in question when the stop is levered; and in which the protruding parts of the escape wheel are flexible; in which each protruding part is arranged so as to be able to bend in a general plane perpendicular to an axis of rotation of the stop (14), while undergoing elastic distortion under the action of said radial force; characterised in that each protruding part has a resilient capacity enabling it to elastically absorb, during said elastic distortion under the action of said radial force, most of a maximum mechanical energy that the mechanical resonator may have when the horology movement is functioning normally.

2. The horology movement according to claim 1, characterised in that a plurality of rigid parts (44) attached to the escape wheel (16), are respectively arranged behind the plurality of flexible protruding parts (42), relative to the normal direction of the stepping rotation of the escape wheel, so that each flexible protruding part (42) is retained by the corresponding rigid part during a shock, among said successive shocks, which may occur between this protruding part and either one of the two mechanical pallet stones (28, 29), to prevent or limit a recoil of this protruding part during this shock in a tangential direction, relative to said axis of rotation of the escape wheel, and allow dissipation of most of a kinetic energy that the escape wheel has at the beginning of this shock.

3. The horology movement according to claim 1 or 2, characterised in that the escapement or a mechanism for driving the escape wheel (16) is arranged so that, when the horology movement is functioning normally, the escape wheel supplies impulses to the stop (14) for sustaining an oscillation of the mechanical resonator (2), these sustaining impulses having a constant energy as long as the horology movement is functioning normally.

4. The horology movement according to claim 3, characterised in that the escapement (12) comprises a magnetic system (30, 32, 36) magnetically coupling the escape wheel (16) and the stop (14), this magnetic system being arranged so as to generate, when the horology movement is functioning normally, magnetic impulses that form said constant energy sustaining impulses.

5. The horology movement according to claim 4, characterised in that said magnetic impulses are generated by two mechanical pallet stones (28, 29) that respectively support two magnets (30, 32) forming two magnetic pallet stones; and in that the stop (14) is arranged so as to be able, when the horology movement is functioning normally, to substantially transmit a magnetic force couple generated by each of the magnetic impulses to its fork (18) in order to sustain an oscillation of the mechanical resonator (2).

6. The horology movement according to claim 4 or 5, characterised in that the protruding parts (42) are arranged so as to allow the assembly formed by the mechanical resonator (2) and by the escapement (12) to self-start when the barrel spring is rewound, after the horology movement has stopped, and the escape wheel (16) is again rotated.

7. The horology movement according to any of claims 4 to 6, characterised in that the magnetic system comprises at least one circular magnetic track (36) supported by a disc (34) forming the escape wheel; in that the plurality of protruding parts (42) are arranged in a general plane parallel to and away from the disc; and in that the plurality of rigid parts (44) are fastened to the disc and project from it towards said general plane.

8. The horology movement according to claim 7, characterised in that the plurality of rigid parts is formed of a plurality of pegs (44) fastened to said disc.

9. The horology movement according to any of claims 4 to 8, characterised in that the protruding parts are formed by teeth (42) arranged on the periphery of a plate (40) forming the escape wheel.

10. The horology movement according to claim 9, characterised in that, when any tooth in the plurality of teeth distorts, the bend of this tooth is limited by a corresponding stop (40, 43) comprised in the escape wheel (16).

11. The horology movement according to any of the preceding claims, characterised in that the stop (14) also has a certain resilient capacity allowing it to elastically absorb, when said one of the two mechanical pallet stones comes up against a protruding part (42) while the escape wheel is positioned within said corresponding range of angular positions and when the mechanical resonator is then braked by the stop, part of a mechanical energy that the mechanical resonator has at the beginning of such an event, the pallets and the protruding part in question together having a resilient capacity allowing them to elastically absorb, during said event, the maximum mechanical energy that the mechanical resonator can have when the horology movement is functioning normally.