Patent Grant
11934150
This application claims priority to European Patent Application No. 20174394.5 filed on May 13, 2020, the entire disclosure of which is hereby incorporated herein by reference.
The invention relates to horological movements comprising an escapement provided with a stopper cooperating, on the one hand, with a toothed escapement wheel and, on the other hand, with a mechanical resonator.
In particular, the invention relates to a horological movement provided with an escapement comprising a magnetic coupling system between a toothed escapement wheel and an anchor. As in the case of a Swiss anchor, the anchor has a reciprocating movement which is synchronous, but different from the periodic movement of the mechanical resonator, this anchor being arranged so as to periodically stop the escapement wheel so that the latter has a step-by-step rotation which is clocked by the mechanical resonator. “Magnetic escapement” means an escapement provided with magnets arranged partly on the anchor and partly on the escapement wheel so as to generate a magnetic coupling between the anchor and the escapement wheel.
The Swiss anchor escapement has been known for a very long time.
In normal operation, the teeth of the escapement wheel cooperate with two pallets of the anchor in a determined manner allowing step-by-step rotation of the escapement wheel which is synchronous with the oscillation of the mechanical resonator, namely in general a balance spring. When the force torque supplied to the escapement wheel decreases as the barrel spring relaxes, the sustaining pulses generated by the escapement and transmitted to the resonator gradually decrease in intensity so that when the wheel ends up stopping while said force torque falls below a limit value, the energy stored in the resonator is relatively low. Thus, the risk of a pallet or a tooth of the escapement wheel being damaged during a possible terminal impact between a pallet and a tooth, depending on the angular stop position of the escapement wheel, is relatively low although not excluded. The situation is more problematic in the case of a horological movement provided with a constant force drive system for the escapement wheel, because the resonator retains substantially the same mechanical energy throughout the operation of the escapement until the escapement wheel and its drive are stopped. The risk of an accidental event at the end of the horological movement is therefore increased.
Document FR 1 047 551, in particular on page 4 in the second and third complete paragraphs on this page, and document U.S. Pat. No. 2,717,488, in particular in lines 39 to 61 of column 4, describe a timepiece escapement comprising an escapement wheel provided with teeth having an elasticity in the tangential direction, but with good rigidity in the radial direction, in order to be able to damp the tangential impacts occurring between the teeth of the escapement wheel and the two pallets of the anchor during normal operation of the escapement. In order to be able to reduce the variation in the pulses supplied to the anchor by the escapement wheel, patent application EP 2 801 868 A2 proposes an escapement wheel provided with teeth mounted on flexible blades oriented radially, so that these blades can easily be deformed under the action of a tangential force. Abutments formed by the configuration of the escapement wheel in the general plane of the teeth are provided to limit such tangential deformation and also rotation of the teeth.
In the context of the development which led to the invention, it has been observed that the problem indicated above becomes a major drawback in the case of a horological movement comprising a hybrid, magnetic and mechanical escapement. Indeed, it has been observed that the risk of a terminal impact between the anchor and the escapement wheel increases sharply in the case of a hybrid escapement, namely an escapement provided with a magnetic coupling system between the anchor and the escapement wheel, with magnetic potential energy ramps allowing the accumulation of potential magnetic energy in the escapement with each step of the step-by-step rotation of the escapement wheel before generating a magnetic pulse at the end of the step, while this escapement wheel is stopped. The escapement wheel of the hybrid escapement comprises projecting parts intended to cooperate with the mechanical pallets of the anchor in at least one phase of the operation of the escapement (for example at start-up and more particularly during normal operation of the horological movement, to absorb kinetic energy at each step of the escapement wheel and define angular stop positions for the escapement wheel, as will be explained in the detailed description of the invention). Indeed, the hybrid escapement has the risk of the escapement wheel stopping in an unfavourable angular position while the mechanical resonator still has nominal mechanical energy. First, sustaining pulses are magnetic pulses having a constant value as long as the force torque supplied to the escapement wheel is greater than or equal to a certain lower limit. Then, as soon as the force torque is below this lower limit, the escapement wheel can no longer properly climb the next magnetic potential energy ramp, so that the escapement wheel will not stop in a next normal angular stop position, but substantially at the bottom of or along a magnetic potential energy ramp. Therefore, as the mechanical resonator oscillates normally during such an event since it has previously received magnetic pulses of substantially constant intensity (nominal intensity), if a mechanical pallet appears in front of a tooth during the next switching of the anchor, a strong impact may occur and damage the escapement wheel or the anchor, or even the mechanical resonator. This increased technical problem therefore requires an appropriate technical solution.
To this end, the invention relates to a horological movement comprising a mechanical resonator and an escapement which is associated with this mechanical resonator, the escapement comprising an escapement wheel, provided with a plurality of projecting parts, and a stopper comprising two mechanical pallets, forming two mechanical abutments for the plurality of projecting parts, and a fork arranged to cooperate with the mechanical resonator via a periodic engagement of a pin, integral with this mechanical resonator, between two horns of the fork. The mechanical resonator is coupled to the stopper so that, during normal operation of the horological movement, the stopper undergoes a reciprocating movement between two rest positions wherein this stopper alternately remains during successive time intervals. The escapement is arranged so as to allow, during normal operation of the horological movement, absorption of kinetic energy of the escapement wheel by successive impacts, between the plurality of projecting parts and alternately the two mechanical pallets, respectively at the end of successive steps of a step-by-step rotation of the escapement wheel. According to the invention, the escapement is arranged so that, when the stopper is switched from a first of its two rest positions towards the second rest position, while the escapement wheel has any angular position in a plurality of ranges of angular positions corresponding respectively to the plurality of projecting parts, one of the two mechanical pallets abuts against a projecting part corresponding to the concerned range of angular positions before the stopper can reach an angular position of disengagement of the pin on the side of the second rest position, said one of the two mechanical pallets then exerting on said projecting part a radial force, relative to the axis of rotation of the escapement wheel, the intensity of which depends on said any angular position of the escapement wheel. Then, the projecting parts of the escapement wheel are flexible and each is arranged so as to be able to bend, in a general plane perpendicular to an axis of rotation of the stopper, undergoing a radial elastic deformation under the action of said radial force, each projecting part having an elastic capacity allowing to elastically absorb, during said elastic deformation, most of a maximum mechanical energy that the mechanical resonator can have during normal operation of the horological movement.
In the general embodiment explained above, the flexible projecting parts are configured and the elasticity coefficients of these flexible projecting parts are selected so as to allow good elastic absorption of the mechanical energy of the mechanical resonator in the case of stopping the escapement wheel in an angular position of the range of angular positions corresponding to the concerned projecting part, while the mechanical resonator oscillates with an amplitude corresponding to a normal operation of the horological movement, and so as to allow a good non-elastic absorption of the kinetic energy of the escapement wheel at the end of each step of its step-by-step rotation during normal operation. It will be noted that it is possible to have, in particular for two main reasons, these two properties of different natures thanks to a judicious configuration of the projecting parts and the choice of elasticity coefficients/elastic deformation capacities, in the radial and angular directions, which are appropriate for the two functions to be performed by the flexible projecting parts. First, the mechanical energy of the mechanical resonator in normal operation is much greater than the kinetic energy of the escapement wheel at the end of each of its steps during the step-by-step rotation of this wheel. The energy ranges involved in these two cases are not of the same order of magnitude. Then, the impact between a mechanical pallet and a projecting part generates, in normal operation, on this projecting part a tangential force, relative to the axis of rotation of the escapement wheel, while the impact between a mechanical pallet and this projecting part, when stopping the escapement wheel in the range of angular positions corresponding to the considered projecting part, generates on this projecting part generally a mainly radial force.
In a preferred embodiment of the invention, a plurality of rigid parts, integral with the escapement wheel, are respectively arranged behind the plurality of flexible projecting parts, relative to the normal direction of the step-by-step rotation of the escapement wheel, so that each flexible projecting part is retained by the corresponding rigid part during an impact, among the successive impacts mentioned above, occurring between this projecting part and either one of the two mechanical pallets, to prevent or limit a recoil of this flexible projecting part during this impact and allow dissipation of most of the kinetic energy that the escapement wheel has at the beginning of this impact. ‘Recoil of a projecting part’ means an angular displacement of the projecting part in the direction opposite to that of the normal rotation of the escapement wheel. Then, the arrangement of the plurality of rigid parts is provided such that when a mechanical pallet abuts against a flexible projecting part and the mechanical resonator is then braked by the stopper, each flexible projecting part subjected to the radial force mentioned above can elastically deform so as to elastically absorb most of the work of this radial force.
In a particular embodiment, the escapement or a mechanism for driving the escapement wheel is arranged so that, during normal operation of the horological movement, the escapement wheel supplies pulses to the stopper for sustaining an oscillation of the mechanical resonator which have a substantially constant energy as long as the horological movement is operating normally.
In a main embodiment, the escapement comprises a magnetic system magnetically coupling the escapement wheel and the stopper, this magnetic system being arranged so as to generate, during normal operation of the horological movement, magnetic pulses which form the constant energy sustaining pulses mentioned above.
In an advantageous embodiment, the stopper also has an elastic capacity allowing it to elastically absorb, when one of the two mechanical pallets abuts against a projecting part while the escapement wheel has an angular position inside the corresponding range of angular positions and the mechanical resonator is braked by the stopper, part of a mechanical energy that the mechanical resonator has at the beginning of such an event. In this case, the anchor and the concerned projecting part together advantageously have an elastic capacity allowing them to elastically absorb during said event a maximum mechanical energy that the mechanical resonator can have during normal operation of the horological movement.
The invention will be described in more detail below using the appended drawings, given by way of non-limiting examples, wherein:
Using the appended figures, a preferred embodiment of a horological 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 the pin 10 were shown. The horological movement comprises an escapement 12 which is associated with the mechanical resonator, the small plate and the pin of which are elements forming this escapement. The escapement 12 further comprises an escapement wheel 16 and an anchor 14 provided with an axis 15 defining its axis of rotation.
The anchor 14 is formed, on the one hand, of a fork 18, comprising two horns 19a and 19b, and of a dart 8 and, on the other hand, of two arms 24 and 26, the free ends of which respectively form two mechanical pallets 28 and 29. A connecting part 25 connects 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 a reciprocating movement, synchronised with the oscillation of the mechanical resonator, between two rest positions, defined by two limiting pegs 21 and 22, wherein the anchor alternately remains during successive time intervals.
The escapement wheel 16 comprises a periodic magnetised structure 36 which is arranged on a disc 34, preferably made of non-magnetic material (not conducting magnetic fields so as not to make the escapement wheel sensitive to external magnetic fields which could exert a significant torque on this escapement wheel if this disc was made of a ferromagnetic material). The structure 36 has magnetised portions 38, which are generally circular-arc shaped, which define increasing ramps of magnetic potential energy for the two magnetic pallets 30 and 32, which each have an axial magnetisation with a polarity opposite to that of the axial magnetisation of the periodic magnetised structure 36 so as to generate magnetic repulsion between the magnetic pallets and the magnetised structure. Each magnetised portion has an increasing monotonic width. In particular, the width of the magnetised portions 38 increases, over their entire useful length, linearly depending on the angle at the centre. According to an advantageous variant, the periodic magnetised structure 36 is arranged so that its outer periphery is circular, the circular-arc shaped magnetised portions of this magnetised structure having the same configuration and being arranged circularly around the axis of rotation of the escapement wheel 16.
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 force torque supplied to the escapement wheel is substantially equal to a nominal force torque (case of a mechanical movement provided with a constant force system for driving the escapement wheel) or comprised in a range of values intended to ensure the normal operation of the horological movement (case of a conventional mechanical movement having a variable force torque applied to the escapement wheel depending on the level of winding of the barrel(s)). The increasing ramps of magnetic potential energy are climbed, when the anchor undergoes a reciprocating movement between its two rest positions and when the force torque supplied to the escapement wheel is equal to said nominal force torque or comprised within the range of values provided for this force 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 reciprocating movement of the anchor. The two magnetic pallets and the increasing ramps of magnetic potential energy are arranged so that the anchor can undergo a pulse of magnetic force in the direction of its movement, after either one of the two magnetic pallets has climbed any one of said increasing ramps of magnetic potential energy, when the anchor switches from the rest position corresponding to a magnetic coupling between the concerned magnetic pallet and said any magnetic potential energy ramp to its other rest position.
The escapement wheel further comprises projecting parts 42 which are associated respectively with the magnetised portions 38 and therefore with the increasing ramps of magnetic potential energy. These projecting parts are formed, in the variant shown, by flexible teeth 42 extending at the periphery of a plate 40 with which the teeth are integral, this plate being integral with the escapement wheel and located above the disc 34 which carries the magnetised structure 36. The heads of the flexible teeth are located respectively at the widest end of the magnetised portions 38 and are partially superimposed on these magnetised portions. Flexible teeth and mechanical pallets are formed by a non-magnetic material. Preferably, the plate 40 is also formed by a non-magnetic material and it is integrally formed with the teeth.
In the advantageous variant shown, the teeth 42 extend in a general plane wherein 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 magnetised structure, located below the general plane. However, in an advantageous variant, the escapement wheel further comprises an upper magnetised structure, of the same configuration as the lower magnetised structure and supported by an upper disc, preferably formed of a non-magnetic material. The lower and upper magnetised structures together form the periodic magnetised structure. They have the same magnetic polarity, opposite to that of the two anchor magnets, and are arranged on either side of the geometric plane wherein these two magnets forming the two magnetic pallets are located, preferably at the same distance.
The escapement 12 is a hybrid-type escapement, that is to say magnetic and mechanical escapement, which allows to improve the behaviour of a magnetic escapement in normal operation (that is to say during stable operation, occurring after a start-up phase, with a force torque MRE supplied to the escapement wheel which is substantially equal to a nominal force torque or within a range of values PVM intended to ensure the normal operation of the horological movement, in particular correct step-by-step rotation of the escapement wheel). In addition, the escapement 12 allows to obtain a self-starting of the assembly formed of the escapement and the mechanical resonator. The role of the teeth 42 of the escapement 12 during normal operation of the horological movement will be explained below, in particular using
In general, the escapement 12 is arranged so as to allow, during normal operation of the horological movement, absorption of kinetic energy of the escapement wheel by successive impacts, between the plurality of projecting 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 escapement wheel. The anchor 14 and the escapement wheel 16 are arranged such that, in normal operation, one of the teeth 42 of the escapement wheel undergoes at least one impact on either one of the two mechanical pallets after the corresponding magnetic pallet has climbed any one of the increasing ramps of magnetic potential energy following a switching of the anchor. This impact occurs so as to at least partially dissipate kinetic energy of the escapement wheel gained following said switching. The teeth of the escapement wheel are therefore designed to be able, during normal operation of the horological movement, to absorb the kinetic energy of this escapement wheel, at each step of the escapement wheel, in a non-elastic manner, after an accumulation of magnetic potential energy in the escapement provided for a next sustaining magnetic pulse of the mechanical resonator, and thus to limit or even prevent a terminal oscillation of the escapement wheel, thanks to the high damping provided, during each step of its step-by-step rotation.
In the preferred variant described, in normal operation and once the escapement wheel momentarily stopped, a flexible tooth 42 presses against a mechanical abutment/a stop surface of the anchor formed by either one of the two mechanical pallets. Thus, for a conventional horological movement, it is expected, in normal operation and for the entire range of values PVM of the force torque MRE, that the escapement wheel becomes momentarily stationary, after at least a first impact of any one of its teeth against any one of the two mechanical pallets 28, 29 and before a subsequent switching of the anchor, at an angular stop position wherein the any tooth presses against the any mechanical pallet. Each angular stop position is thus defined by a tooth bearing against a mechanical pallet, as shown in
For the function of the flexible teeth 42, in normal operation, to be carried out efficiently, it is important that these teeth have a relatively high rigidity during the tangential impacts of their respective heads against the mechanical pallets while the escapement wheel is driven step by step in its normal direction of rotation. Thus, it is expected that the desired rigidity is seen for a relatively large tangential force, exerted by a mechanical pallet on the head of any flexible tooth, having a direction opposite to the normal direction of rotation of the escapement wheel. To this end, a plurality of rigid parts, formed in particular by pegs 44 fixed to the disc 34 and rising therefrom in the direction of a general plane wherein the flexible teeth 42 extend, are respectively arranged at the rear of the plurality of flexible teeth, so as to neutralise or inhibit most of the flexibility of these teeth during successive impacts, provided in normal operation, to absorb kinetic energy of the escapement wheel at the end of each step of its step-by-step rotation and to limit or even prevent an oscillation of the escapement wheel following an accumulation of magnetic potential energy preceding a first impact between a mechanical pallet and a tooth at the end of each step.
In general, the plurality of rigid parts (retaining pegs 44), integral with the escapement wheel 16, are respectively arranged behind the plurality of flexible projecting parts (flexible teeth 42), relative to the normal direction of step-by-step rotation of the escapement wheel. The configuration of the flexible teeth 42 and the retaining pegs 44 is provided so that each peg substantially blocks any movement of the corresponding tooth in a tangential direction and in a direction opposite to that of the normal rotation of the escapement wheel, so that each flexible tooth 42 is retained by the corresponding peg during an impact occurring, in normal operation, between this flexible tooth and either one of the two mechanical pallets of the anchor, to prevent or greatly limit a recoil of this flexible tooth during this impact and allow dissipation of most of the kinetic energy that the escapement wheel has at the beginning of this impact.
In the specific variant shown in the figures, the flexible teeth 42 have a particular configuration with a head 42a, a nose of which in turn abuts, in normal operation, against one and, subsequently, the other of the two mechanical pallets of the anchor, a rigid or semi-rigid body 42b and an end part 42c which is formed by a flexible blade oriented mainly tangentially relative to the centre of the escapement wheel, more particularly substantially parallel to the direction tangential to the end of the nose of the considered flexible tooth, this end defining the point of impact with each mechanical pallet during normal operation of the horological movement. The end part of each tooth is fixed to a base 43 projecting from the plate 40 and having an orientation substantially perpendicular to this end part, the base being according to the rigid or semi-rigid variant. ‘Semi-rigid’ means a rigidity much greater than that of the flexible blade in its transverse direction in the general plane of the flexible tooth, and therefore less elasticity without having a rigidity practically excluding any elastic deformation during an impact.
It will be noted that the configuration of the flexible teeth 42 provided in the aforementioned specific variant is also advantageous and adapted for the general embodiment described above in the summary of the invention. Indeed, the flexible teeth have a relatively high elasticity in the radial direction at the top of their head (in the case of a frontal impact between a pallet and the top of a tooth head when the horological movement stops operating normally, situation which will be described in more detail hereinafter with reference to
In the preferred embodiment, in the variant shown in the figures, retaining pegs 44 are arranged behind the bodies 42b of the flexible teeth, at a short distance from these tooth bodies or bearing against them. Since the elasticity of each flexible tooth is mainly integrated into its end part 42c and since the flexible blade which forms it is expected to be oriented mainly tangentially relative to the point of contact between the flexible tooth and the retaining peg, this tooth has as desired a relatively high rigidity upon impact between its nose and either one of the two mechanical pallets in normal operation (as indicated, the flexible blade which forms the end part of the tooth has a relatively strong elasticity in the direction transverse to this blade, but relatively high rigidity in its longitudinal direction). Each retaining peg 44 has at least two functions in normal operation of the horological movement, namely a first function consisting in blocking the elastic joint formed by the flexible end part 42c of the corresponding flexible tooth to obtain a relatively high rigidity of this tooth upon tangential impact 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 escapement wheel during such a tangential impact.
Then, the flexible teeth 42 and the mechanical pallets 28, 29 are arranged so that, during a new winding of the barrel spring following a stop of the horological movement and allowing the escapement wheel 16 to rotate in the intended direction of rotation, at least one of the two mechanical pallets 28, 29 contacts a tooth 42 of the escapement wheel, which are configured so that the escapement wheel can supply the anchor 14 with a start-up mechanical force torque and therefore a start-up mechanical pulse. Thus, efficient and rapid self-starting of the assembly formed of the escapement 12 and the mechanical resonator 2, and therefore of the mechanical horological movement, is made possible. The escapement wheel subjected to said start-up torque is not stopped by the contact between the concerned flexible tooth and mechanical pallet, and the flexible tooth is arranged in association with the retaining peg 44 so as to be able to at least partially transmit said start-up torque to the anchor.
In the variant shown in the figures, each of the flexible teeth 42 has, in a polar coordinate system which is centred on the axis of rotation of the escapement wheel 16, a first inclined surface SI1 which is inclined so that each of the first and second mechanical pallets 28, 29 can, in a start-up phase, slide on this first inclined surface while the escapement wheel passes through a corresponding range of angular positions θ. ‘Inclined surface’ in a polar coordinate system, means a surface which is neither radial nor tangential. In addition, each of the two mechanical pallets of the anchor has, in the polar coordinate system associated with the escapement wheel, a second inclined surface SI2 when the considered pallet is in contact with one of the teeth 42 of the escapement wheel. The second inclined surface is configured so that each of the teeth 42 can, in a start-up phase, slide on this second inclined surface when the escapement wheel passes through a range of angular positions A which corresponds to a contact area between the considered tooth and mechanical pallet.
For the start-up phase, it is sufficient that an oscillation of the mechanical resonator can be activated and with it the reciprocating movement of the anchor which then allows to sustain this oscillation by magnetic pulses. Thus, the fact that the flexible teeth may have a certain elastic deformation in a radial direction is not a crucial fact for the starting function, although this may decrease the efficiency of the intended start-up torque. To limit radial elastic deformation of the flexible tooth towards the centre of the escapement wheel, the flexible teeth, the retaining pegs and the mechanical pallets are arranged so that the reaction force exerted upon start-up by a mechanical pallet in contact with a flexible tooth, as the escapement wheel begins to rotate, has an overall orientation which passes, in the polar coordinate system of the escapement wheel, above the point of contact between the body 42b of the concerned tooth and the retaining pin located behind this tooth body. In particular depending on the inclination of the inclined surface of the mechanical pallet while a head 42a of a flexible tooth bears against it, a certain frictional force between this head and the inclined surface may be favourable. However, this frictional force must not be too great to allow the tooth to slide along this inclined surface to generate a start-up pulse.
The incorporation of teeth 42 to allow either one of the two functions described above, namely the damping of oscillations of the escapement wheel during a step-by-step rotation of the latter in normal operation and a self-starting of the assembly formed by the mechanical resonator and the escapement, in particular an escapement of the magnetic type, has the consequence that, during a switching of the anchor 14 from a first of its two rest positions in the direction of the second rest position while the escapement wheel 16 is positioned in any angular position A from a plurality of ranges of angular positions 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 disengagement of the pin on the side of the second rest position, as shown in
When the barrel spring relaxes, there comes a point when the horological movement ceases to function normally given that the force torque which the barrel can provide to the gear train and the escapement wheel becomes insufficient to ensure such normal operation. At a certain moment, as shown in
It will be noted that the frontal impact of substantially radial direction does not relate only to the instant at which the mechanical pallet and the tooth are contacted, but it is about a radial force pulse which has a certain duration given that this frontal impact takes place while the pin of the oscillating resonator is inserted between the two horns 19a and 19b of the fork 18 and a magnetic pulse is supplied to the anchor. During the aforementioned impact, the radial force pulse has several components:
The more the braking of the mechanical resonator during the aforementioned impact is violent/has a strong intensity, the stronger the force exerted orthogonally on the horn 19a by the mechanical resonator, and by construction in a substantially tangential manner in a polar coordinate system associated with the anchor, and the reaction force of the anchor which brakes this mechanical resonator at the beginning of the impact. This poses a major problem, which is why the escapement wheel 16 is arranged and configured to be able to prevent breakage or deterioration of one of its parts, of the anchor or even of a part of the mechanical resonator during an event as shown in
To this end, the teeth 42 of the escapement wheel 16 are provided flexible and each is arranged so as to be able to bend, in a general plane perpendicular to an axis of rotation of the anchor 14, undergoing an elastic deformation under the action of a radial force, relative to the axis of rotation of the escapement wheel, which is exerted by one of the two mechanical pallets abutting against the considered flexible tooth while the escapement wheel has any angular position within a corresponding range of angular positions, mentioned above, and the mechanical resonator is braked by the anchor. Each flexible tooth has an elastic capacity allowing to elastically absorb, during said elastic deformation under the action of said radial force, most of the maximum mechanical energy that the mechanical resonator may have during normal operation of the horological movement. It will be noted that, during the impact between the mechanical pallet and the flexible tooth, there is a certain dissipation of energy, in particular in the mechanical resonator and the anchor, and also in other concerned structures, in particular in the plate 40 and the bearings of the escapement wheel. Thanks to the invention, any breakage or deterioration of the escapement and of the mechanical resonator can thus be avoided. It has already been explained previously that the flexible teeth 42 were configured so as to have mainly an elasticity in a radial direction passing through the top of their head 42a. Indeed, the end part 42c of each tooth having the greatest flexibility, and therefore the greatest elastic capacity, is formed by a flexible blade which is oriented mainly orthogonally to said radial direction.
‘Flexible tooth’, generally means a projecting element of which at least a part and/or a part for connecting this element to a support can deform elastically during an impact, which is in particular substantially radial, that this element can undergo under the action of a mechanical pallet of the anchor, having an elastic capacity sufficient to elastically absorb a significant part of the mechanical energy of the mechanical resonator that the anchor can transmit to this element while the mechanical resonator, initially having a mechanical energy corresponding to a normal operation of the horological movement, is close to its rest position and suddenly braked, in particular to zero speed, by the anchor, a mechanical pallet of which abuts against the projecting element. ‘Elastic capacity’ means an elastic energy absorbing capacity, the elastic energy being the energy stored in a stressed material in the form of elastic deformation. Thanks to the features of the escapement wheel according to the invention, an excessively sudden impact between the latter and the anchor is avoided and a progressive dissipation of the mechanical energy of the mechanical resonator when the escapement wheel stops is allowed, therefore regardless of its angular position.
In
In the case of a frontal impact of a substantially radial direction between the mechanical pallet 29 and a flexible tooth 42 shown in
In an advantageous variant, the flexible teeth 42 are arranged to bear against the retaining pegs 44 with a pre-stress, that is to say with a certain initial elastic deformation which is generated by the retaining pegs on the respective teeth in the absence of other forces. Such a prestress allows to increase the elastic absorption capacity of the flexible teeth over a given displacement distance from an initial position, abutting against the respective pegs, and a final position where these teeth abut on a base 43 of a tooth downstream of and/or on the periphery of the plate 40 which supports the flexible teeth at its periphery, as in the variant shown in the figures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20174394 | May 2020 | EP | regional |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2717488 | Linard | Sep 1955 | A |
| 20200089168 | Di Domenico et al. | Mar 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 703449 | Jan 2012 | CH |
| 1427316 | Jul 2003 | CN |
| 110928170 | Mar 2020 | CN |
| 2 801 868 | Nov 2014 | EP |
| 2801868 | Nov 2014 | EP |
| 3037894 | Jun 2016 | EP |
| 3182224 | Jun 2017 | EP |
| 3217227 | Sep 2017 | EP |
| 3 627 242 | Mar 2020 | EP |
| 1.047.551 | Dec 1953 | FR |
| 505059 | May 1939 | GB |
| Entry |
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| Combined Chinese Office Action and Search Report dated May 23, 2022, in Chinese Patent Application No. 202110527234.1 (with English translation), 12 pages. |
| European Search Report dated Oct. 14, 2020 in European Application 20174394.5 filed May 13, 2020 (with English Translation of Categories of Cited Documents), 3 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20210356911 A1 | Nov 2021 | US |
