Abstract:
A shock-absorber bearing for a staff of a moving part of a timepiece, the bearing including a support including a housing configured to receive a pivot module configured to cooperate with the staff, and an elastic mechanism configured to exert at least one axial force on the pivot module to retain the module in its housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a National phase application in the U.S. of International Patent Application PCT/EP2013/062801filed Jun. 19, 2013 which claims priority on European patent application No. 12173045.1 filed Jun. 21, 2012. The entire disclosures of each of which are hereby incorporated herein by reference. 
     The present invention relates to a shock-proof bearing for a staff of a moving part of a timepiece. The staff comprises a small rod, comprising a support, said support being provided with a housing which is intended to receive a pivot system into which the small rod is inserted. The shock-proof bearing comprises furthermore elastic means designed to exert at least one axial force on said pivot system in order to retain said pivot system in the housing. 
     The technical field of the invention is the technical field of precision engineering. 
     TECHNOLOGICAL BACKGROUND 
     The present invention relates to bearings for timepieces, more particularly of the type allowing shocks to be absorbed. The constructors of mechanical watches have, for a long time, been designing numerous devices which allow a staff to absorb the energy resulting from a shock, in particular a lateral shock, by abutment against a wall of the hole of the base block which it traverses, whilst allowing a momentary displacement of the small rod before it is returned to its lock position under the action of a spring. 
       FIGS. 1 and 2  illustrate a device termed inverted double cone which is currently used in timepieces found on the market. 
     A support  1 , the base of which comprises a hole  2  for the passage of the balance staff  3  ended by a small rod  3   a , makes it possible to position a jewelled bearing  20  in which there are immobilised a pierced stone  4  traversed by the small rod  3   a  and a counter-pivot stone  5 . The jewelled bearing  20  is retained in a housing  6  of the support  1  by a spring  10  which, in this example, comprises radial extensions  9  which compress the counter-pivot stone  5 . The housing  6  comprises two bearing surfaces  7 ,  7   a  in the form of inverted cones on which the complementary bearing surfaces  8 ,  8   a  of the jewelled bearing  20  are supported, said bearing surfaces requiring to be produced with very great precision. In the case of an axial shock, the pierced stone  4 , the counter-pivot stone  5  and the balance staff are displaced and the spring  10  acts alone to return the balance staff  3  into its initial position. The spring  10  is dimensioned to have a displacement limit so that, beyond this limit, the balance staff  3  comes into contact with stops  14  making it possible for said staff  3  to absorb the shock, which the small rods  3   a  of the staff  3  cannot do without the risk of breaking. In the case of lateral shock, i.e. when the end of the small rod unbalances the jewelled bearing  20  out of its lock plane, the spring  10  cooperates with the complementary inclined planes  7 ,  7   a;    8 ,  8   a  in order to re-centre the jewelled bearing  20 . Such bearings have been sold for example under the trademark Incabloc®. These springs can be produced in chromium-cobalt alloy or brass and are manufactured by traditional cutting means. 
     Now, a disadvantage of these shock-absorber bearings is that they are dismantlable. In fact, it is intended that these shock-absorber bearings are able to be dismantled for servicing operations after sale and maintenance. Shock-absorber bearings are therefore obtained, the assembly of which is not easy. Effectively, some parts, such as the support  1  and the spring  10 , must be orientated and manipulated in a certain manner during the assembly operation in order to assemble the shock-absorber bearing. Consequently, not only are the constituent parts of the shock-absorber bearing complex but furthermore total automation of the assembly is not possible and makes said shock-absorber bearing more expensive. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to remedy the disadvantages of prior art by proposing to provide a non-dismantlable shock-absorber bearing of a timepiece which is simple to mount. 
     To this end, the invention relates to a shock-absorber bearing for a staff of a moving part of a timepiece, said bearing comprising a support provided with a housing which is intended to receive a pivot module designed to cooperate with said staff, said bearing comprising furthermore elastic means designed to exert at least one axial force on said pivot module in order to retain said module in its housing, characterised in that the elastic means comprise an annular spring and are fixed to the support permanently by a material linkage between said elastic means and the support, said annular spring comprising at least two specific attachment zones for fixing said annular spring to the support. 
     A first advantage of the present invention is to make it possible to have a non-dismantlable shock-proof system which is simple to produce and to assemble. In fact, the present invention has the advantage of having parts which are placed one on the other without requiring to be manipulated in a particular manner. Hence, the assembly process can be automated. This simplicity of the parts and of the assembly process makes it possible to have an inexpensive shock-absorber. 
     In a first advantageous embodiment, the elastic means are fixed on the support by welding/soldering. 
     In a second advantageous embodiment, the elastic means are fixed on the support by gluing. 
     In a third advantageous embodiment, the elastic means comprise an annular spring which has at least one internal radial extension extending towards the centre of said annular spring. 
     In another advantageous embodiment, said annular spring comprises at least two external radial extensions which extend towards the outside of said annular spring and serve as specific attachment zones. 
     In another advantageous embodiment, the annular spring comprises three external radial extensions and three internal radial extensions. 
     The present invention likewise relates to a clock movement comprising a bottom plate and at least one bridge, said bottom plate comprising an orifice. Into said orifice of said bottom plate, a shock-absorber bearing according to the invention is inserted. 
     The present invention likewise relates to a clock movement comprising a bottom plate and at least one bridge, said at least one bridge comprising an orifice. Into said orifice of said at least one bridge, a shock-absorber bearing according to the invention is inserted. 
     In an advantageous embodiment, the support of the shock-absorber bearing and said bottom plate are monobloc. 
     In an advantageous embodiment, the support of the shock-absorber bearing and said at least one bridge are monobloc. 
     The invention likewise relates to a timepiece comprising a width closed by a casing and a base. The timepiece comprises a clock movement according to the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The aims, advantages and features of the shock-absorber bearing according to the present invention will appear more clearly in the following detailed description of at least one embodiment of the invention which is given solely by way of non-limiting example and illustrated by the annexed drawings in which: 
         FIGS. 1 and 2 , already cited, make it possible to represent schematically a shock-absorber system of the timepiece according to prior art; 
         FIG. 3  represents schematically a shock-absorber system of the timepiece according to the invention; 
         FIG. 4  represents schematically a view from above of a spring for the shock-absorber system of the timepiece according to the invention; 
         FIGS. 5 and 6  represent schematically various views of a preferred embodiment of a spring for the shock-absorber system of the timepiece according to the invention; 
         FIGS. 7 to 9  represent schematically various variants for the pivot module of the shock-absorber system of the timepiece according to the invention; and 
         FIG. 10  represents schematically a monobloc variant of the shock-absorber system of the timepiece according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention arises from the general inventive idea which consists of producing a simple non-dismantlable shock-absorber system. This shock-absorber system is designed to be mounted on a bottom plate and/or on at least one bridge of a clock movement. The clock movement is placed in a timepiece comprising a width closed by a base and a crystal. 
     In  FIG. 3 , a shock-absorber bearing, also termed shock-proof system  100 , is represented. This shock-absorber bearing  100  comprises a support  200 . This support  200  has the shape of a base  201 , provided with a hole  202 , from which a peripheral rim  203  extends. The latter has an external flank  204  and an internal flank  205 . This rim  203  makes it possible to define a housing  206  into which a pivot module  400  is inserted. This standard pivot module  400  comprises a jewelled bearing  401 , i.e. a part which has a circular central orifice and an external wall and an internal wall. Into the internal wall, a pierced stone  402  is inserted, the diameter of which corresponds to that of the central orifice. The internal wall comprises a shoulder so that a counter-pivot stone  403  can be fixed. The pivot module  400  is then placed in the housing  206  of the support  200  and cooperates with the small rod of a staff. Preferably, the support  200 , the housing  206  and the pivot module  400  have a circular shape. 
     The shock-absorber bearing  100  comprises furthermore elastic means  300  which are designed to cooperate with the pivot module  400  so as to absorb shocks and to return the pivot module  400  into its lock position when the stress associated with the shocks subsides. 
     Advantageously according to the invention, the elastic means  300  are fixed so as to be integral with the support  200 . There is understood by this that the elastic means  300 , once fixed to the support  200 , can no longer be separated, made non-integral with the support. The elastic means  300  are fixed permanently to the support  200 . The fixing of the elastic means  300  to the support  200  is therefore definitive. In order to do this, the elastic means  300  are fixed on the support  200  by welding or soldering or gluing. A material linkage therefore exists between the elastic means  300  and the support  200 . This linkage can be made of glue or soldering or welding. The elastic means  300  form a cover placed on the support which retains the pivot module  400  in the housing  206 , the shock-proof system  100  thus becoming non-dismantlable. 
     This fixing to the support  200  takes place at the level of the rim  203 . The rim  203 , at its end  207 , has a surface  207   a  acting as support surface on which the elastic means  300  can be fixed. The external flank  204  of the support  200  can likewise act as surface on which the elastic means  300  are fixed. 
     The advantage of such a feature is to make it possible to have a simplified shock-absorber bearing  100  for there is no longer the constraint of being dismantlable and therefore the shapes can be more simple. 
     During assembly of the shock-proof system  100 , an axial mounting is used. The first step therefore consists of providing the support  200 . Then the pivot module  400  is provided which is placed in the housing  206  of the support. Then, the elastic means  300  are placed and fixed. In the case of elastic means  300  fixed to the end  207  of the support  200  acting as support surface  207   a , the elastic means  300  are simply placed on the support  200 . Spots of glue or welding are then applied in order to fix said elastic means  300 . 
     In an embodiment of the elastic means, the elastic means  300  have the shape of an annular spring  301 . This annular spring is of the flat type, i.e. it is formed from a metallic strip, i.e. which has a greater width than thickness. In order to place said pivot module  400  in the housing  206  of the support  200 , the annular spring  301  comprises internal radial extensions  302 . These internal radial extensions  302  are formed by the strip which forms the spring  301  and are curved back towards the inside of the spring  301 . These internal radial extensions  302  are preferably distributed regularly over the flat spring  301  so that the annular spring  301  can act homogeneously as can be seen in  FIG. 4 . The fixing of the annular spring  301  to the support  200  takes place at the level of circular portions  303  situated between the internal radial extensions  302 . The annular spring  301  can be produced in a metallic material such as brass or any other material which can be used in timepiece applications. 
     In a first advantageous variant, the annular spring  301  comprises specific attachment zones  304 , as can be seen in  FIGS. 5 and 6 . In fact, in the case of the annular spring  301  which can be seen in  FIG. 4 , the fixing to the support  200  by the circular portions  303  can involve a modification of the properties of the annular spring  301 . 
     Now, the specific attachment zones  304  are zones designed to limit the influence of the fixing by welding or gluing on the properties of said annular spring  301 . These zones have the shape of external radial extensions  304   a  which extend towards the outside of the spring  301 . It is understood therefore that these specific attachment zones  304  are formed by the strip forming the spring  301  which is curved back towards the outside of the spring  301 . For preference, the curve of the external radial extensions  304 a is less pronounced than those of the internal radial extensions  302 . It is understood by this that the distance between the ends of the external radial extensions  304   a  and the strip forming the spring  301  is larger than the distance between the ends of the internal radial extensions  302  and said strip forming the spring  301 . The annular spring  301  according to this variant is advantageously dimensioned so that, during fixing of said spring  301  to the support  200 , only the specific attachment zones  304  formed by the external radial extensions  304   a  are in contact with the support  200  which allows the fixing. This configuration makes it possible for the zones other than these specific attachment zones  304  to be deformed freely when an axial stress is applied on the pivot module  400  by the staff. 
     For preference, the annular spring  301  is designed to have three internal radial extensions  302  and three specific attachment zones  304 , i.e. three external radial extensions  304   a . The three internal radial extensions  302  are designed to be offset relative to each other by 120°. The three external radial extensions  304   a  are designed to be offset relative to each other by 120°. Providing external radial extensions  304   a  and internal radial extensions  302  is produced so that the external radial extensions  304   a  and the internal radial extensions  302  are alternated and offset relative to each other by 60°. It is understood that an internal radial extension  302  is situated between two external radial extensions  304   a.    
     The advantage of the shock-absorber bearing  100  is of not having any specific orientation. In fact, as all the constituent parts of said shock-proof system  100  are circular, there is no need to orientate them relative to each other. The support  200  has no particular zones on which the annular spring  301  must be fixed. In this way, the assembly process of such a shock-absorber system  100  can be automated to the full. 
     In a second variant, the internal flank  205  has an inclined portion which allows better centring of the pivot module  400 . In fact during an axial shock, the staff exerts an axial force on the pivot module  400  so that the latter lifts and deforms the elastic means  300 . These elastic means  300  retain the pivot module  400  so that, when the latter is no longer subjected to a stress, the elastic means  300  resume their lock position and place the pivot module  400  in the housing  206 . Now, when the pivot module  400  is lifted from the housing  206  by the staff, it is possible that the pivot module  400  becomes offset under the effect of a force such as gravity and is displaced radially. In this case, when the pivot module  400  resumes its position in the housing  206 , the pivot module  400  will come into contact with the inclined portion of the internal flank  205 . This inclined portion  205  guides the pivot module  400  towards its initial position, i.e. its lock position, so that the pivot module  400  is perfectly centred. 
     In a third variant the pivot module  400  has the monobloc shape. 
     In a first alternative which can be seen in  FIG. 7 , the pivot module  400  comprises a single stone  410 . This single stone  410  has a cylindrical shape which has a small height relative to the radius. This single stone  410  comprises, at the level of its central axis, a recessed hole  411  into which the small rod of the staff can be inserted. This configuration with a single stone  410  makes it possible to have a pivot module  400  which is more compact and simplified because it makes it possible to have a shock-absorber system  100  composed of only three parts: the support  200 , the single stone  410  and the annular spring  301 . Consequently, the dimensions of the support  200  can be reduced. 
     In a second alternative which can be seen in  FIG. 8 , the pierced stone  430  and the counter-pivot stone  420  are fixed to each other without the intermediary of an jewelled bearing. For this, the counter-pivot stone  420  acts as jewelled bearing. The counter-pivot stone  420  is then provided with a peripheral rim  421  which defines a housing  422  in which the pierced stone  430  is placed. This alternative makes it possible to have a simplified pivot module  400  but having dimensions similar to those of a pivot module  400  with jewelled bearing. The dimensions of the support remain therefore unchanged in order to be adapted to this alternative. 
     In another alternative which can be seen in  FIG. 9 , the pierced stone  450  and the counter-pivot stone  440  are monobloc. The pivot module  400  resembles the pivot module of the second alternative except that, instead of having the pierced stone  450  and the counter-pivot stone  440  fixed to each other, they are directly integral via the slant of an attachment element  445 . The advantage accrues here of having a single part whilst keeping standard dimensions to the standard pivot modules comprising a jewelled bearing in which a pierced stone and a counter-pivot stone are placed. 
     In another variant which can be seen in  FIG. 10 , the support is monobloc with the place on which the shock-absorber bearing is fixed. In fact, a shock-absorber bearing is designed to be installed at the level of a bridge or of a bottom place of a clock movement. This clock movement has traversing orifices produced on the bottom plate or the bridges. In these orifices, a shock-proof system  100  is inserted, each orifice being dimensioned so that the support  200  can be slid there. 
     In order to achieve an assembly step, the support is directly produced on the bridge or bridges and the bottom plate in order to form a shock-absorber assembly  1000 . The bottom plate and/or the bridges form the support  2000 , machined to leave a base  2001  comprising a hole  2002  exposed. The support  2000  has a housing  2006  in which the pivot module  400  is placed. The annular spring  301  is fixed on the upper face of the support  2000 . This variant likewise makes it possible to have one part less because the support  200  no longer exists. 
     It will be understood that various modifications and/or improvements and/or combinations which are evident to the person skilled in the art can be applied to various embodiments of the invention, presented above without departing from the scope of the invention defined by the annexed claims.