Patent Publication Number: US-2020285196-A1

Title: Horological torque limiting mechanism

Description:
FIELD OF THE INVENTION 
     The invention relates to an internal torque limiting mechanism for a horological movement, said torque limiting mechanism including a first wheel including a first felloe and arranged to pivot about a first axis of rotation relative to a structure or a plate or a bridge, said first wheel including at least a first elastic arm which, in the free state of said first wheel, projects along the direction of said first axis of rotation relative to said first felloe, and at least a second wheel including a second felloe and arranged to pivot relative to said structure about a second axis of rotation parallel or merged with said first axis of rotation overlapping at least partially with said first wheel. 
     The invention further relates to a barrel winding device including a control member arranged to be operated by a user and to actuate an input pinion engaging with said first wheel or said second wheel of such a torque limiting mechanism, included in said device. 
     The invention further relates to a horological movement including, between an input mechanism and an output mechanism, such a torque limiting mechanism. 
     The invention further relates to a timepiece, particularly a watch, including at least such a torque limiting mechanism, and/or at least such a movement. 
     The invention relates to the field of horological mechanisms, and more particularly the protection of certain mechanisms against an excessive torque addition, in particular energy recharging mechanisms such as winding mechanisms, or correction and/or display mechanisms, in particularly calendar or similar mechanisms. 
     BACKGROUND OF THE INVENTION 
     Some horological mechanisms are designed to store and restore large quantities of energy, however, the dimensioning thereof is limited by that of the case of the timepiece in question, and it is not possible to apply high safety coefficients thereto to protect same against an excessive torque that might be applied thereto. The large size of known torque limiting mechanisms restricts the integration of complications in the timepiece. In addition, the user does not have the option of knowing whether they have correctly performed, completely safely, a complete setting, in particular for winding a mechanism. 
     The document CH703483A2 held by SEIKO describes a wheel with a torque limiting mechanism comprising a penetration arm part extending from a proximal end part to a distal end part equipped with a penetration addendum, which is engaged elastically in a pressure-engaged part. The addendum is detached from the engaged part to rotate the crown wheels when a torque exceeding a threshold value is applied. A force directed from the proximal end part to the distal end part is applied to the projection when a manual winding torque is applied to the mechanism and suitable for separating the projection from the engaged part. 
     SUMMARY OF THE INVENTION 
     The invention proposes to produce a very compact, economical, torque limiting device, the use whereof enables the user to determine readily the proper completion of a setting by said user. 
     For this purpose, the invention relates to an internal torque limiting mechanism for a horological movement, according to claim  1 , 
     The invention further relates to a barrel winding device including such a torque limiting mechanism. 
     The invention further relates to a horological movement including, between an input mechanism and an output mechanism, such a torque limiting mechanism. 
     The invention further relates to a timepiece, particularly a watch, including at least such a torque limiting mechanism, and/or at least such a movement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the invention will emerge on reading the following detailed description, with reference to the appended drawings, wherein: 
         FIG. 1  represents, schematically, and in a perspective view, a torque limiting mechanism according to the invention, including a first upper wheel and a second lower wheel, which are held in frictional engagement, at the level of the elastic arms included in each thereof, by an upper travel limiter herein consisting of a shoulder screw, and by a lower structure herein consisting of a bridge or similar; 
         FIG. 2  represents, schematically and in a cross-sectional view, the engagement of the elastic arms of the two wheels in  FIG. 1 ; 
         FIG. 3  represents, schematically and in a top view, the first wheel in  FIG. 1 ; 
         FIG. 4  represents, schematically and in a diametrical cross-sectional view, the wheel in  FIG. 3 ; 
         FIG. 5  represents, schematically and in a side view, in the free state, the wheel in  FIG. 3 ; 
         FIG. 6  represents, schematically and in a perspective view, a barrel winding device, including the torque limiting mechanism in  FIG. 1 , and including a control member, herein consisting of a shaft actuating a winding-mechanism pinion arranged to be operated by a user and to actuate an input pinion engaging with the second wheel, and where the first wheel engages with a barrel ratchet; 
         FIG. 7  represents, schematically and in a perspective view, the barrel winding device in  FIG. 6  assembled on a barrel bridge whereon the wheels and the ratchet pivot, and which supports the shoulder screw acting as a travel limiter; 
         FIG. 8  represents, schematically and in a side view, the wolf-tooth winding-mechanism pinion in  FIG. 6 ; 
         FIGS. 9 and 10  represent, in a similar manner to  FIGS. 1 and 2  respectively, the engagement of the first wheel and the second wheel with normal pressure; 
         FIGS. 11 and 12  represent, in a similar manner to  FIGS. 1 and 2  respectively, the engagement of the first wheel and the second wheel immediately prior to disconnection; 
         FIGS. 13 and 14  represent, in a similar manner to  FIGS. 1 and 2  respectively, the engagement of the first wheel and the second wheel immediately after disconnection; 
         FIG. 15  represents, schematically and in a cross-sectional view, the mechanism in  FIG. 7 ; 
         FIG. 16  represents, schematically and in a perspective view, an alternative embodiment where the first wheel and the second wheel are not coaxial; 
         FIG. 17  represents, schematically and in a perspective view, an alternative embodiment where the torque limiting mechanism includes three stacked, coaxial wheels; 
         FIG. 18  represents, schematically and in an exploded view, the mechanism in  FIG. 17 ; 
         FIG. 19  represents, schematically and in an exploded perspective view, an alternative embodiment where the torque limiting mechanism includes two different wheels, one including elastic arms in a circular arc shape, the other with radial elastic arms; 
         FIG. 20  is a block diagram representing a watch including a movement which includes a barrel winding device, including such a torque limiting device; 
         FIG. 21  is a block diagram representing a watch including a movement which includes such a torque limiting mechanism, between an input mechanism and an output mechanism. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention relates to a horological torque limiting mechanism  100 . This mechanism  100  includes a first wheel  1 , which includes a first felloe  10  and is arranged to pivot about a first axis of rotation D 1  relative to a structure  4  or a plate or a bridge. 
     This first wheel  1  includes at least a first elastic arm  31 , which, in the free state of the first wheel  1 , projects along the direction of the first axis of rotation D 1  relative to the first felloe  10 . More particularly and non-exhaustively, this first elastic arm  31  is movable in a first pressed section  41  of the first wheel  1 . 
     The mechanism  100  includes at least a second wheel  2 , which includes a second felloe  20  and arranged to pivot relative to the structure  4  about a second axis of rotation D 2 , parallel or merged with the first axis of rotation D 1 , overlapping at least partially with the first. 
     The mechanism  100  includes a travel limiter  5 , which is fastened to the structure  4 , and which is arranged to hold the second wheel  2  on the first wheel  1  for the engagement thereof in frictional pressure in certain relative angular positions. 
     The invention is herein more particularly described in the simplified case where the mechanism  100  merely includes the first wheel  1  and the second wheel  2 , those skilled in the art would be able to extrapolate to a greater number of wheels, for a mechanism including more than one input and one output. 
     The invention proposes to vary the frictional pressure between the first wheel  1  and the second wheel  2 . 
     For this purpose, the second wheel  2  and/or the travel limiter  5  and/or the structure  4  includes at least one relief forming a ramp, and which projects along a direction parallel or merged with that of the first axis of rotation D 1 . This relief is arranged, in certain relative angular positions of the component bearing this relief relative to the first wheel  1 , to engage in frictional pressure with at least a first elastic arm  31  of said first wheel  1 , and, in further relative angular positions, allow a frictionless relative travel between the first wheel  1  and the component bearing this relief. 
     When the structure  4  or the travel limiter  5  includes such a relief, the mechanism forms a simple pawl, arranged to vary the axial position of the first elastic arm of the first wheel  1 , or to vary the axial position of the entire first wheel  1  and thus vary the frictional pressure applied on the second wheel  2 . 
     The invention relates more particularly to the case where the second wheel  2  includes at least a second arm  32  forming a ramp and which, in the free state of the second wheel  2 , projects along the direction of the second axis of rotation D 2  relative to the second felloe  20 . 
     More particularly, this second arm  32  is a second elastic arm  32 . Even more particularly, this second arm  32  is a second elastic arm  32  movable in a second pressed section  42 . 
     When only the first wheel  1  and the second wheel  2  include reliefs projecting relative to the respective felloe thereof, they are mounted top-to-tail, with each first elastic arm  31  projecting towards the second wheel  2 , and with said second arm  32  projecting towards the first wheel  1 . 
     In an alternative embodiment and as seen in  FIG. 16 , the second axis of rotation D 2  is at a distance from the first axis of rotation D 1 . 
     In a further alternative embodiment and as seen in most of the other figures, the second axis of rotation D 2  is merged with the first axis of rotation D 1 . 
     More particularly, each second arm  32  is arranged to engage successively, upon a relative rotation of the second wheel  2  relative to the first wheel  1 , cyclically with the first felloe  10 , a first elastic arm  31 , and a first pressed section  41  before returning in engagement with the first felloe  10 . 
     It is understood that the first wheel  1  and the second wheel  2  are arranged, if they are coaxial, to rotate in the same direction: either they both rotate in the same direction, or one rotates and the other is locked. These wheels may, in other applications where they are not coaxial, rotate in opposite directions of one another. 
     Each first elastic arm  31  of the first wheel defines a first ramp, which starts at the level of a hinge  310  with the first felloe  10 , and rises to the level of a first apex. More particularly and as seen in the figures, this first elastic arm  31  is an overhanging arm, and the apex is coincident with the distal end of this first arm  31 , the edge whereof defines a first front surface  311 . In this particular alternative embodiment, any relief of an opposing wheel, in particular the second wheel  2 , during a rotation still in the same direction of each wheel, climbs up this first ramp, then drops after passing the apex; according to the configuration, this relief drops onto the first felloe  10 , or into the first pressed section  41 . This jump corresponds to the disconnection of the mechanism. 
     In further alternative embodiments not illustrated, the first elastic arm  31  includes an upward ramp from the first felloe  10  to the first apex, then a downward ramp from the first apex to the first felloe  10 . In the same way, the relief of the second wheel  2  may be formed in different manners, the figures represent this relief in the form of a second elastic arm  32  similar to the first elastic arm  31  of the first wheel  1 , this configuration is advantageous as it makes it possible to use, for this first wheel  1  and the second wheel  2 , identical components, at least at the level of these reliefs engaging with one another; obviously, according to the application, the first wheel  1  and the second wheel  2  may include different toothings, according to the components of the movement with which they engage. 
     More particularly, each first elastic arm  31  is arranged to engage successively, upon a relative rotation of the second wheel  2  relative to the first wheel  1 , with the second felloe  20 , a second arm  32 , and a second pressed section  42  included in the second wheel  2 , before returning in engagement with the second felloe  20 . 
     The arrangement with a first front surface  311 , and a similar second front surface  312  for the second elastic arm, enables, in a particular direction of rotation, engagement abutting with one another, and rotational actuation by mere, frictionless, pressure of a wheel with another, whereas, in the opposite direction of rotation, the elastic arms engage progressively to an unclicking position where one of the wheels is no longer actuated by the other. 
     In a particular alternative embodiment illustrated by the figures, each first elastic arm  31  is a substantially annular sector which extends substantially concentrically relative to the first axis of rotation D 1 . The radial cross-section thereof may be constant, or indeed progressive or degressive, so as to obtain a variable friction according to the relative angle between the opposing wheels. Preferably, the top surface of the first elastic arm  31  extends, radially relative to the first axis of rotation D 1 , perpendicularly thereto. In a non-illustrated alternative embodiment, this first elastic arm  31  may, further, be warped or slanted. Each second elastic arm  32  may be formed in a similar fashion. And in particular, more particularly, each second elastic arm  32  extends substantially concentrically relative to the second axis of rotation D 2 . 
     In a further alternative embodiment and as seen in  FIG. 19 , at least a first elastic arm  31  or/and at least a second arm  32  extends substantially radially relative to the axis of rotation of the wheel bearing same. 
     More particularly, and as seen in  FIGS. 17 and 18 , the mechanism  100  includes, at least partially superimposed along a direction parallel with the axis of rotation of each thereof, more than two wheels arranged to engage pairwise in frictional pressure, and all mounted trapped between the structure  4  and the travel limiter  5 , and at least one intermediate wheel between the end wheels includes at least one elastic arm projecting from each side of the felloe thereof, along the axial direction thereof: this is the case of the second wheel  2  in  FIG. 18 , which engages, on the top side of the second felloe  20 , with the first wheel  1 , and, on the bottom side of the second felloe  20 , with the relief  39  projecting from the third felloe  90  of a third wheel  9  pressing on the structure  4 . 
     As seen in  FIGS. 6 and 7 , the invention further relates to a barrel winding device  200 , including a control member  201  which is arranged to be operated by a user, such as a control shaft, a button, a trigger-piece, a bezel, or similar, to actuate an input pinion  202  engaging with the first wheel  1  or the second wheel  2  of such a torque limiting mechanism  100 , included in this device  200 . More particularly, the other wheel of this mechanism  100 , the second wheel  2  or respectively the first wheel  1 , is arranged to actuate a ratchet  203  of a driving or striking-mechanism barrel, the whole being assembled on the structure  4  which is, in this particular case, a barrel bridge. The travel limiter  5  is advantageously a screw fastened to this structure, which facilitates the assembly of the overall mechanism  100  and enables the dismantling thereof. 
     Thus, particularly and specifically to the invention, the usual crown wheel is split into two plates, forming the first wheel  1  and the second wheel  2 , and advantageously in a very economical embodiment, first  31  and second  32  elastic arms are pressed and bent in each thereof. These plates are then mounted top-to-tail in place of the crown wheel. The first wheel  1  engages with a winding-mechanism pinion  202 , and the second wheel  2  engages with the barrel ratchet  203 . The first wheel  1  and the second wheel  2  are rigidly connected by means of the elastic arms  31  and  32 , which transmit a frictional torque. If the torque applied to the winding-mechanism pinion  202  is excessive, the elastic arms  31  and  32  are distorted and slide against one another, until the system disconnects. During disconnection, the jump performed by the elastic arms  31  and  32  during unclicking produces a characteristic noise which gives the user the indication that the barrel is fully recharged. 
     In the alternative embodiment illustrated by the figures, each wheel  1 ,  2 , includes three elastic arms  31   32 . After disconnection, the first wheel  1  performs a third of a turn. 
     More particularly, the play between the felloes of the two wheels is between 0.06 and 0.10 mm, and the axial elastic travel of each arm is half the value of this play. 
     The invention further relates to a horological movement  500  including, between an input mechanism  300  and an output mechanism  400 , such a torque limiting mechanism  100 . 
     More particularly, the input mechanism  300  is a calendar or date mechanism, and the output mechanism  400  is a mechanism for displaying the month, or day of the week, or date. Also, the torque limiter  100  is arranged to command, upon any jump of an arm of a wheel  1  or  2  of the torque limiter  100 , the gain by one step of the display in question. For example, the command to correct the display of the day of the week is a cyclical command for which the device according to the invention is well suited. Similarly, a clear date correction setting may be obtained. 
     The invention is readily adaptable to any semi-instantaneous or dragging display: months, days, time zones, hours, or others. 
     The invention is also suitable for producing a reverser for mono- or bidirectional winding: the first wheel  1  engages with an oscillating automatic winding mass, and the second wheel  2  engages with the winding train. When the first wheel  1  turns in the clockwise direction, the system unclicks and the second wheel  2  does not turn. When the first wheel  1  turns in the anticlockwise direction, it actuates the second wheel  2  via the distal ends  311 ,  321 , of the elastic arms  31  and  32 . Thus, more particularly, the movement  500  includes an oscillating automatic winding mass and an automatic winding train, and such a torque limiter  100  including elastic arms  31 ,  32 , forms a reverser for mono- or bidirectional winding, the first wheel  1  engaging with the oscillating automatic winding mass, and the second wheel  2  engaging with the winding train, such that, when the first wheel  1  turns in the clockwise, or respectively anticlockwise, direction, the system unclicks and the second wheel  2  does not turn, and when the first wheel  1  turns in the anticlockwise, or respectively clockwise, direction, it actuates the second wheel  2  via distal ends  311 , 321 , included respectively in the elastic arms  31 ,  32 . 
     The invention is also suitable for producing a brake-lever, for example to prevent a barrel from being discharged. The ratchet may be provided with elastic arms, and the barrel bridge with notches, such that the ends of the arms fall into the notches. Thus, more particularly, the movement  500  includes at least a barrel and a ratchet arranged on a barrel bridge, and such a torque limiter  100  forms a brake-lever, to prevent a barrel from being discharged, the ratchet forming one of the wheels  1 ,  2 , and including elastic arms, and the barrel bridge forming a structure  4  and including notches, such that the ends of the arms fall into the notches. 
     More particularly, the input mechanism  300  is a minute repeater release mechanism, and the output mechanism  400  is a minute repeater mechanism. The torque limiter  100  is then arranged to command, upon any jump of an arm of a wheel  1  or  2  of the torque limiter  100 , the control of a lifting-lever, included in the minute repeater mechanism, to inhibit the command of a further repeater during the execution of a repeater striking-mechanism. 
     The invention further relates to a timepiece  1000  including at least such a torque limiting mechanism  100 , and/or at least such a movement  500 . More particularly, this timepiece  1000  is a watch. 
     In sum, the proposed mechanism is very simple, as it requires no elastic return means other than those borne by the first wheel  1 , and preferably the second wheel  2 . In particular, it is not necessary to insert, in the space defined by the structure  4  and the travel limiter  5 , a spring to press the first wheel  1  and the second wheel  2  against one another. 
     The coaxial arrangement of the wheels is particularly advantageous, as the pressures exerted on the wheels are symmetrical, and the transmissible pressure is maximal. In the case where the arrangement in the horological movement involves offsetting the first  1  and the second  2  wheels, it is advantageous to increase the number of elastic arms to prevent dead angles. 
     The embodiment of the wheels may stem, very economically, from stamping, the wheels may be identical, and optionally differ solely by the toothing thereof. 
     The invention enables the user to ensure that the function performed, winding, display correction, release, is completed properly, and ensures the protection of the components of the mechanism in question against any excessive torque. For example, the user can wind a barrel completely without being concerned about breaking a component.