Timepiece balance

A balance staff including a main shoulder of a balance, a first radial lateral bearing surface for this balance, a roller sleeve shoulder, and a balance spring collet shoulder. The roller shoulder is adjacent to a first radial shoulder, the collet shoulder is adjacent to a second lateral surface, which defines, with the first radial shoulder, a collar including the balance shoulder which is adjacent to a first lateral bearing surface for the bearing of a balance, the first lateral bearing surface facing the same side as the first radial shoulder, the balance shoulder is separated from this collet shoulder by a seat forming the largest diameter of the collar.

FIELD OF THE INVENTION

The invention concerns a timepiece movement including at least one combined unit formed of a sprung balance assembly and a pallet lever, said sprung balance assembly comprising an equipped balance including a balance, whose hub is mounted on an equipped staff; said equipped staff includes a roller sleeve, carrying a pin and at least one notch, and said roller sleeve being driven onto a shoulder of the roller of a timepiece balance staff, said staff including, about a main pivot axis:

a main shoulder for the radial centring of said balance, and, adjacent to said main shoulder, a first lateral bearing surface extending substantially radially and receiving said balance in axial abutment,

a collet shoulder for the radial centring of a balance spring collet comprised in said sprung balance assembly, said collet shoulder and said main shoulder being at a distance from each other and arranged to maintain a distance from each other, said collet being mounted on said collet shoulder and said balance being mounted on said main shoulder,

said staff forming a stepped hub including at both ends thereof, in proximity to end pivots, on the one hand, said roller shoulder, which is adjacent to a first radial shoulder, and on the other hand, said collet shoulder, which is adjacent to a second lateral surface, said first radial shoulder and said second lateral surface defining together a collar, said collar in turn including said main shoulder which is adjacent to said first lateral bearing surface for the axial bearing of said balance, and said first lateral bearing surface being turned to the same side as said first radial shoulder, and said balance shoulder being separated from said collet shoulder by a peripheral portion forming a seat, which forms the largest diameter of said collar and of said staff, the balance hub being mounted via a bore comprised in said main shoulder and also mounted bearing, via a first bearing surface of said balance, on said first lateral bearing surface, said hub being held, on a second surface of said balance axially opposite said first bearing surface, by a sharp rivet edge formed from a local deformation of a lip of said staff, said balance being confined between said first lateral bearing surface and said sharp rivet edge,

the abutment limit of the balance being located on the opposite side to said roller shoulder and said sleeve being driven in on the opposite side to said balance relative to said sharp rivet edge, said balance spring collet, to which is attached at least one balance spring, being mounted by clamping on said staff and bearing in abutment on said second lateral surface, and said pallet lever being arranged to cooperate with said pin and said notch, and said pallet lever including a lever whose pivot defines a pallet lever pivot axis parallel to said main axis, said lever carrying a dart in the alignment thereof, and a set of horns arranged to cooperate with said pin as close as possible to said main shoulder, said dart being arranged to cooperate with said notch as far as possible from said main shoulder, and said set of horns being arranged in a substantially parallel plane to a plane defined by said lever and said dart.

The invention also concerns a timepiece including at least one such timepiece movement.

The invention concerns the field of timepiece mechanisms, and more specifically the field of combined units with a sprung balance and lever escapement mechanism.

BACKGROUND OF THE INVENTION

In a conventional mechanism, a balance staff carries a balance fixed via a hub of the balance felloe, and held bearing on a surface of a first side of a median seat of the balance staff. On this first side, beyond the hub, a collet fitted onto the staff in proximity to a first end thereof forms the moveable point of attachment of a balance spring which is also attached to a plate or bar. On the second side of the balance staff, opposite the side carrying the collet, the staff carries, away from the median seat, first of all a large roller carrying an impulse pin which cooperates with the pallet fork, then a small roller with a notch cooperating with a dart of the same pallet lever to prevent any accidental movements of the fork.

The safety devices should be of sufficient size in the transverse direction of the movement, i.e. parallel to the pivot axes of the balance and of the pallets. Particular attention must be given to the safety device between the surface of the large roller facing the pallets and the corresponding surface of the lever which carries the horns delimiting the pallet fork. The same applies between the end of the impulse pin, also called the roller pin, and the surface of the dart facing said pin. The same attention must be given to the safety device between the other surface of the dart and the plate carrying the combined unit.

In numerous movements, the pallet/balance settings are insufficient, which causes a risk of collision, and these settings are in general out of balance.

It is clear that making these safety devices too large is detrimental to the total thickness of the movement, the section of whose components is constant?.

A compromise must therefore be found between operating safety, to prevent any risk of collision, and the total thickness of the movement.

It is not always easy to move components in order to provide safety devices, because of the presence of various bridges, the balance felloe, and other mechanisms with which there is a risk of interference, for example the date discs, which form a barrier preventing stones or incablocs from being moved to provide for security devices, particularly because of the safety device required between the balance felloe and the oscillating weight, which is provided by platforms in a fixed position, and which prevent the balance felloe being moved axially.

Further, the conventional solution is to provide adequate safety devices and settings, to the detriment of the thickness of the movement.

U.S. Patent No. 2010/157743 in the name of Roger Dubuis discloses a particular method of fixing the balance spring to the collet by matching a balance spring to a balance, and the assembly of the balance spring on the balance with a collet selected from among a collection of collets suited to different attachment distances of the inner coil relative to the staff. The balance thus includes a removable collet for attaching the balance spring. This balance includes a median seat, on each side of which are held bearing, on a first side, the balance beyond which a collet is driven in, and on a second side, a sleeve with the two rollers and the impulse pin.

CH Patent No 270582A in the name of Brendler discloses a conical balance staff onto which is fitted a first sleeve which carries, on a first side, a balance which bears on a first surface of the first sleeve forming a first seat and is immobilised by a first sharp rivet edge on the first end side of the staff, said first sharp rivet edge forming a second seat on which a collet is held bearing, the collet being immobilised by a sharp rivet edge at the first end of the first sleeve. The first sleeve also carries, on a second side, a second sleeve, which bears on a second surface of the first sleeve and carries balance rollers and is immobilised by a sharp rivet edge on the second end side of the first sleeve and corresponds to the second end of the balance staff.

FR Patent Application No. 1216100 A in the name of Pizon discloses several balance embodiments. In a first embodiment, a balance includes, on either side of a seat, on a first side, the balance supported on one surface and immobilised by the collet driven onto the staff, and on a second side a double roller mounted on a conical shoulder of the staff. The other embodiments include a sleeve with a single-piece double roller with a seat for the balance supported on one surface of the seat on the opposite side to the rollers, the collet abuts on a surface of the sleeve without any contact with the balance, and is mounted, depending upon the case, directly on the sleeve or on a threaded arbour on which the sleeve is mounted.

CH Patent No 95065 in the name of Koehn discloses a balance including, mounted on a smooth staff with a single shoulder, a sleeve including, beyond the two rollers, a balance-seat immobilised by a sharp rivet edge on the opposite side to the rollers, the collet being driven further onto the sleeve.

CH Patent No 474101 in the name of Fabriques de Balanciers Réunies discloses, a sleeve including a double roller, which is fitted onto a smooth staff, wherein the large roller with the impulse pin is also used as a direct support for the balance, which is immobilised on the opposite side by the collet driven onto the sleeve.

GB Patent No 831161 in the name of Smith, discloses a single-piece balance, with the pin and the notch on a first side of the felloe, and an off-centre collet on the other side of the felloe.

DE Patent No 2427021 SA1 in the name of Ebauches Bettlach discloses a balance staff including a seat with the notch, the balance felloe is supported on a surface of the seat and carries the impulse pin, the balance is held by the collet driven onto the staff.

U.S. Pat. No. 1,423,480, in the name of Needy, discloses several balance embodiments. In a first embodiment, a staff including a conical shoulder carries a first sleeve on which the balance is supported on an opposite side surface to the collet which is supported on said first sleeve, the first sleeve is held on the locally threaded conical staff by a nut in a recess in the first sleeve; and a second sleeve with a double roller and impulse pin is fitted onto a shoulder of the staff beyond the first sleeve. The other embodiment includes a ring screwed onto the staff underneath the first sleeve to hold the latter.

CH Patent Application No 700260 A2 in the name of Cartier discloses a single-piece staff with a median seat, on a first side of which the balance felloe bears, and beyond, the collet is fitted onto another shoulder, the seat forming the large roller carrying the impulse pin and the staff including the small roller on the second side opposite the balance.

SUMMARY OF THE INVENTION

The invention proposes to improve the safety devices between an equipped sprung balance assembly and a lever escapement mechanism. The object of the design of a particular type of balance is to improve the poising between the safety devices and the settings. The invention is of versatile nature, so as to be applicable to the conversion of existing movements, by modifying or replacing the smallest possible number of components.

Finally, the optimisation provided by the invention makes it easier to produce ultra-flat movements.

For a given movement height, the object of the invention is to balance the escapement settings and to increase the safety devices between the various components, to remove the risk of collisions.

The solution sought takes the utmost account of production costs, and strives to affect the minimum number of components.

To this end, the invention concerns a timepiece movement including at least one combined unit formed of a sprung balance assembly and a pallet lever, said sprung balance assembly comprising an equipped balance including a balance, whose hub is mounted on an equipped staff; said equipped staff includes a roller sleeve carrying a pin and at least one notch, and said roller sleeve being driven onto a shoulder of the roller of a timepiece balance staff, said staff including, about a main pivot axis:

a main shoulder for the radial centring of said balance, and, adjacent to said main shoulder, a first lateral bearing surface extending substantially radially and receiving said balance in axial abutment,

a collet shoulder for the radial centring of a balance spring collet comprised in said sprung balance assembly, said collet shoulder and said main shoulder being at a distance from each other and arranged to maintain a distance from each other, said collet being mounted on said collet shoulder and said balance being mounted on said main shoulder,

said staff forming a stepped hub including at both ends thereof, in proximity to end pivots, on the one hand, said roller shoulder, which is adjacent to a first radial shoulder, and on the other hand, said collet shoulder, which is adjacent to a second lateral surface, said first radial shoulder and said second lateral surface defining together a collar, said collar in turn including said main shoulder which is adjacent to said first lateral bearing surface for the axial bearing of said balance, and said first lateral bearing surface facing the same side as said first radial shoulder, and said balance shoulder being separated from said collet shoulder by a peripheral portion forming a seat, which forms the largest diameter of said collar and of said staff, the balance hub being mounted via a bore comprised in said main shoulder and also mounted bearing, via a first bearing surface of said balance, on said first lateral bearing surface, said hub being held, on a second surface of said balance axially opposite said first bearing surface, by a sharp rivet edge formed from a local deformation of a lip of said staff, said balance being confined between said first lateral bearing surface and said sharp rivet edge,

the abutment limit of the balance being located on the opposite side to said roller shoulder and said sleeve being driven in on the opposite side to said balance relative to said sharp rivet edge, said balance spring collet, to which is attached at least one balance spring, being mounted by clamping on said staff and bearing in abutment on said second lateral surface, and said pallet lever being arranged to cooperate with said pin and said notch, and said pallet lever including a lever whose pivot defines a pallet lever pivot axis parallel to said main axis, said lever carrying a dart in the alignment thereof, and a set of horns arranged to cooperate with said pin as close as possible to said main shoulder, said dart being arranged to cooperate with said notch as far as possible from said main shoulder, and said set of horns being arranged in a substantially parallel plane to a plane defined by said lever and said dart,

characterized in that said movement includes a plate carrying a first pallet-stone, and a pallet bridge carrying a second pallet-stone, said pallet lever is pivotally guided between said pallet-stones, said plate carrying a first shock resistant balance guide member including first means for the pivotal guiding of said staff about said main axis, and said movement including a balance bar carrying a second shock resistant balance guide member including second means for the pivotal guiding of said staff about said main axis, said sprung balance assembly being pivotally guided between said shock resistant guide members, and in that said dart is closer than said horns to the shock resistant guide member which is farthest from said balance spring.

The invention also concerns a timepiece including at least one such timepiece movement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention concerns the field of timepiece mechanisms, and more specifically the field of combined units with a sprung balance and lever escapement mechanism.

The invention proposes to improve the safety devices between an equipped sprung balance assembly and a lever escapement mechanism.

The invention first of all concerns a timepiece balance staff1, illustrated inFIGS. 1 and 2to9, respectively showing a first preferred variant and other non-limiting variants of the invention.

The monolithic axial component guided by pivots on the plate and the bar, which carries the other components of the sprung balance will be referred to here as “staff1”. Depending upon its shape and structure, this staff1will be designated11(smooth) or110(stepped).

A sub-assembly, which is in a kit or pre-assembled, ready to receive a balance and a balance spring collet and including at least one staff1and one sleeve60with at least one roller notch64, will be referred to here as “equipped staff1E”. In some variants, as seen inFIGS. 6 to 9, equipped staff1E also includes components which have to be assembled at the same time as the balance and the balance spring collet: the added seat89, spacer sleeve111, spacer ring208, whose function will be explained below.

An equipped staff1E on which a simple balance2is assembled will be referred to as “equipped balance10”.

An assembly formed of an equipped balance10and at least one balance spring7will be referred to as “sprung balance assembly100”

Timepiece balance staff1includes, about a pivot axis D:a main shoulder5or65for the radial centring of a balance2, and, adjacent to main shoulder5or65, a first lateral bearing surface81or66, which extends substantially radially to receive balance2in axial abutment;a roller shoulder6for the radial centring of a roller sleeve60. “Roller sleeve60” refers to a sleeve with at least one roller notch.a collet shoulder7for the radial centring of a balance spring collet70.

According to the invention, collet shoulder7and main shoulder5or65are at a distance from each other, and arranged so as to maintain at a distance from each other a collet70mounted on collet shoulder7and a balance2mounted on main shoulder5or65. Staff1includes a second lateral bearing surface82or68for receiving in axial abutment a balance spring collet70mounted on collet shoulder7. This second lateral bearing surface82or68is located, either on a seat8located between collet shoulder7and main shoulder5or65, or on a radial shoulder of staff1beyond the projection of main shoulder5or65, on axis D.

The different variants include a main shoulder supporting the balance, referenced main shoulder5inFIGS. 1,4,5,6and7, where the main shoulder is directly arranged on an arbor11or stepped hub110forming the core of staff1. This main shoulder is referenced65inFIGS. 2,3,8and9, where the main shoulder is arranged on a component added to arbor11or hub110, said added component being a roller sleeve60inFIGS. 2 and 3, or a spacer sleeve111inFIGS. 8 and 9. In both cases, this main shoulder is used for the radial centring of hub20of a balance2. Staff1includes, adjacent to main shoulder5or65, a first lateral bearing surface. This first lateral bearing surface is referenced81inFIG. 1and inFIGS. 6 to 9, where it is formed by a lateral surface of an added seat89or of a spacer sleeve111. This first lateral bearing surface is referenced66inFIGS. 2 to 5. In both cases, this first lateral bearing surface extends substantially radially, preferably radially and perpendicularly to axis D of staff1, to receive in axial abutment the hub20of a balance2.

In all the variants illustrated here, balance staff1carries spacer means formed either by a shoulder of an arbor11, or by a stepped hub110forming the core of said staff1; or by a component added to said staff, such as seat8, added seat89, spacer sleeve111, spacer ring208, or added roller sleeve60. The spacer means prevents collet70from bearing directly on the balance felloe as in conventional configurations.

Staff1includes a second lateral bearing surface for receiving in axial abutment a balance spring collet70mounted on collet shoulder7. This second lateral bearing surface is referenced82inFIG. 1and inFIGS. 6 to 9, where it forms the lateral surface of added seat89opposite first lateral bearing surface81. The second lateral bearing surface is referenced68inFIGS. 2 to 5where it is formed, inFIGS. 2 and 3, by an end surface of a roller sleeve60driven onto a rectilinear arbor11, and, inFIGS. 4 and 5, by a shoulder of a collar of a stepped hub110peculiar to these variants.

It is an object of the invention to increase safety devices. A conventional impediment, linked to an ordinary assembly with the stacking, in series, of a collet bearing on a felloe, which in turn bears on a seat, which bears on a roller sleeve, results from the large space required for the seat which is situated between the felloe and the roller sleeve (or the large roller carrying the impulse pin). The invention therefore proposes several configurations for placing the balance hub and roller closer together, by removing from this area, the conventional seat between the felloe and the roller, and moving these latter elements as close as possible to each other, while providing the necessary safety devices. The straightforward removal of the seat is possible, but is not necessary to achieve the object of the invention. Indeed, the bearing surface function, which is traditionally attributed to the seat between the hub and roller of the prior art, may be performed by other components as is seen in the different variants.

Several configurations are possible for receiving a hub20of balance2.

TheFIG. 1variant inverts the usual prior art system of positioning and fixing the balance by 180°. This inversion saves space height-wise between the small and large rollers. Seat8is transferred to the other side of the balance, i.e. it is inserted between hub20of the felloe of balance2and collet70for securing balance spring71. Seat8is used as a support, on one side for collet70, and on the opposite side for hub20. Seat8forms the largest diameter of staff1.

FIG. 1therefore illustrates a first embodiment with a staff1, which includes a single-piece stepped hub110, which incorporates a collar119carrying seat8.

On the hub20side, one of the lateral surfaces of seat8forms a first lateral bearing surface81for the axial abutment of hub20driven onto a main shoulder5of stepped hub110. This main shoulder5is immediately next to said seat8and both are carried by collar119.

On the side of staff1carrying collet70, seat8has a radial shoulder defining a second lateral surface82for receiving in axial abutment said collet70, mounted on a shoulder7comprised in staff1.

Stepped shoulder110also includes, in immediate proximity to first radial shoulder51, a lateral stop surface9for receiving in axial abutment an added balance roller sleeve60, mounted on roller shoulder6; on the side carrying hub20, away from seat8, main support shoulder5of hub20is interrupted by a first radial shoulder, defining a first axial side51, in proximity to which a lateral stop surface9is arranged to act as bearing surface for a roller sleeve60carrying at least one roller notch64. The hub20is preferably fixed by a sharp rivet edge53, folded down into position54after being fitted, as seen inFIG. 1. This sharp rivet edge is set back from lateral stop surface9, to ensure that roller sleeve60is supported on lateral stop surface9and not on the sharp rivet edge, and thus to ensure precise dimensions on the interface with the pallets. Beyond lateral stop surface9, a smooth shoulder6of staff1carries roller sleeve60, including a large roller61, a small roller63, roller notch64in small roller63, and pin62mounted in large roller61in a particular variant.

Thus, lateral stop surface9holds roller sleeve60at a distance from hub20mounted on main shoulder5and held in abutment on first lateral surface81, and prevents any contact between said roller sleeve60and balance2. In the variant ofFIG. 1, roller sleeve60does not participate in the positioning or holding of hub20, and may be independent of staff1. The same applies to the other variants illustrated inFIGS. 7 to 9.

In short, inFIG. 1, staff1is a stepped hub110, which includes at the two ends thereof, in proximity to pivots, a roller shoulder6, which is adjacent to a first radial shoulder51, and a collet shoulder7, which is adjacent to a second lateral surface82. This first radial shoulder51and said second lateral surface82together define a collar119which in turn includes a balance shoulder5, which is adjacent to a first lateral bearing surface81for supporting balance2.

According to the invention, the first lateral bearing surface81faces the same side as the first radial shoulder51. The shoulder5of balance2is separated from collet shoulder7by a peripheral portion forming a seat8which forms the largest diameter of collar119and thus of staff1. This external diameter of seat8is also preferably greater than the external diameter of collet70.

The diameter of the main shoulder5supporting the balance is smaller than that of seat8, and is greater than the diameters of roller shoulder6and of collet shoulder7.

The balance is therefore stopped on the opposite side to roller shoulder6and to rollers61and63.

In a variant that is not illustrated, pin62is fixed to balance2instead of being fixed to sleeve60. This embodiment is applicable to all of the variants illustrated.

In another embodiment that is not illustrated, sleeve60and balance20form a single-piece component. This embodiment is applicable to the variants ofFIGS. 1 to 4.

InFIGS. 2 to 5however, the roller sleeve60necessarily forms part of balance staff1, since it participates in supporting hub20. Roller sleeve60is a component added to a rectilinear arbour11inFIGS. 2 and 3, and to a stepped hub110inFIG. 4. In theFIG. 5variant, the roller sleeve, or at least the small roller63is integrated in a stepped hub110which directly carries hub20.

In the case ofFIGS. 2 to 4, staff1is thus in two parts and includes a roller sleeve60driven onto roller shoulder6comprised in an arbour11, roller60being arranged to form a stop member supporting a balance2mounted on main shoulder5and held in abutment on first lateral surface81.

InFIG. 2, as inFIG. 3, the seat supporting the balance is comprised within sleeve60carrying the double roller; the balance is fixed relative to said sleeve60. Staff1is in two parts and includes a roller sleeve60driven onto roller shoulder6comprised in a rectilinear arbour11, roller60including a first lateral bearing surface66forming a stop member for a balance2mounted on main shoulder65also comprised in roller sleeve60. The end surface68of the double roller of sleeve60is used as an axial support for collet70.

TheFIG. 3embodiment, with pin62in balance20, is even more advantageous than inFIG. 2, since it saves space height-wise and allows for a very compact sprung balance assembly in the axial direction.

InFIG. 4, staff1is in two parts and includes a roller sleeve60driven onto roller shoulder6comprised in a stepped hub110, roller60including a first lateral bearing surface66forming a stop member for a balance2, mounted on main shoulder5comprised in a collar67of stepped hub110. Sleeve60forms an integral part of the balance staff, which is directly supported by and fixed to stepped arbour110; large roller61is no longer used to carry pin62, which is directly carried by balance20, and this shoulder61can therefore have a smaller diameter, since it forms only a simple axial support for the balance.

TheFIG. 5variant differs from that ofFIG. 1, in that it does not have a seat on the side of collet70, and in that the only axial support for hub20is on a shoulder66of stepped hub110. Staff1is a single part and includes a stepped hub110, having a collar61which includes a first lateral bearing surface66forming a stop member for a balance2mounted on main shoulder5which is also comprised in collar61.

To facilitate assembly, roller centring sleeve6preferably has a maximum diameter that is smaller than or equal to the minimum diameter of main shoulder5or65.

In the embodiment ofFIGS. 2 to 4, a roller sleeve60is driven onto roller shoulder6, and includes at least the first lateral bearing surface66adjacent to the main shoulder. This main shoulder is formed either, inFIG. 4, by a main shoulder5comprised in a flange67projecting radially from arbour11, or, inFIGS. 2 and 3, by a shoulder65comprised in roller60adjacent to first lateral bearing surface66.

In a preferred embodiment, staff1is in a single piece and has a lateral stop surface9for receiving in axial abutment a balance roller sleeve60mounted on roller shoulder6, so as to keep roller sleeve60at a distance from a balance2, mounted on main shoulder5and held in abutment on first lateral surface81.

Thus, in the first embodiment ofFIG. 1, staff1is a single-piece stepped hub110and includes, on either side of main shoulder5:a seat8whose diameter is greater than that of main shoulder5, including first lateral surface81for receiving in axial abutment a balance2, and second lateral surface82for receiving in axial abutment a balance spring collet70, mounted on collet shoulder7,a lateral stop surface9, whose diameter is smaller than or equal to that of main shoulder5, for receiving in abutment a balance roller sleeve60, mounted on roller shoulder6.
Staff1Preferably Includes:on a first axial side51of main shoulder5, which is arranged for centring a balance2along a pivot axis D of staff1, and away from main shoulder5:at least one roller shoulder6for centring at least one roller on pivot axis D, roller shoulder6having a diameter smaller than or equal to that of main shoulder5,a first pivotal guide means3about pivot axis D, whose diameter is smaller than or equal to the diameter of roller shoulder6,on a second axial side52, opposite first axial side51of main shoulder5and away from said shoulder5;collet shoulder7for the radial centring of at least one balance spring collet on pivot axis D,a second pivotal guide means4about pivot axis D, whose diameter is smaller than or equal to the diameter of collet shoulder7.

Advantageously according to the invention:the first lateral bearing surface81which is arranged for receiving in abutment the felloe of a balance2, and the second lateral bearing surface82, form two faces of seat8, axially opposite each other along pivot axis D,lateral stop surface9projects axially relative to main shoulder5towards roller shoulder6.

In a preferred embodiment, main shoulder5includes, on a first axial side51facing roller shoulder6, a lip53of small cross-section to form, by sharp rivet edgeing or heading or a similar method, a sharp rivet edge54for locking a hub20of a balance2, mounted on main shoulder5in abutment on first lateral surface81.FIG. 1shows two details, with, to the left of pivot axis D, said sharp rivet edge53as manufactured, substantially parallel to axis D, so as to allow the assembly of hub20of balance2. To the right of pivot axis D, however, this sharp rivet edge is shown in a folded over holding position on hub20at reference54. These details show an upsetting groove allowing material to flow out when the operation to form sharp rivet edge54is carried out.

By way of alternative to forming a sharp rivet edge, it is possible to fix the balance felloe by other means, particularly by clamping it onto the arbour or onto the component carrying the main shoulder, by laser welding, brazing, bonding, local deformation of the arbour or of the component carrying the main shoulder, although these methods are in no way limiting.

In the variants ofFIGS. 2 to 4, to carry hub20, staff1is in two parts and includes a roller sleeve60driven onto roller shoulder6comprised in an arbour11.

In the case ofFIG. 4, hub20carries the impulse pin62. Roller sleeve60, which is added to arbour11, is arranged to form a stop member for a balance2mounted in radial abutment on main shoulder5of arbour11, and held in axial abutment on a shoulder66of a collar61of the roller sleeve60, which is similar to a conventional large roller, but does not carry an impulse pin.

InFIGS. 2 and 3, hub20is in radial abutment on a shoulder65of roller60and in axial abutment on a shoulder66of a collar61of roller sleeve60. InFIG. 2, this collar61forms a conventional roller carrying impulse pin62. However, inFIG. 3, the collar does not form a conventional large roller carrying impulse pin62, since, in a similar manner to theFIG. 4variant, it is also hub20which carries impulse pin62in this variant.

FIG. 5illustrates a single piece version having a stepped hub110with an integrated roller. Hub20carries impulse pin62and is in axial abutment on a surface66of a collar61of stepped hub110and in radial abutment on a shoulder5of said stepped hub110.

In the embodiments ofFIGS. 1 and 2, roller sleeve60includes a large roller61, which carries an impulse pin62, and is integral with a small roller63comprising a roller notch64and farther away than said large roller from the main shoulder, referenced5inFIG. 1,65inFIG. 2.

In the embodiments ofFIGS. 3 and 4, hub2carries an impulse pin62. Roller60carries a large roller61carrying the first lateral bearing surface66, and which is integral with a small roller63comprising a roller notch64and farther away than said large roller from main shoulder5,65.

InFIG. 6, staff1is in two parts and includes an added seat89, driven onto a rectilinear shoulder113comprised in a stepped hub110, between main shoulder5and collet shoulder7, the added seat89including a first lateral bearing surface81and a second lateral bearing surface82. Rectilinear shoulder113includes, on a first axial side51facing roller shoulder6, a lip53of small cross-section to form a sharp rivet edge54locking a hub20of a balance2, mounted on main shoulder5. Stepped shoulder110has a shoulder face112forming an axial stop member for a roller sleeve60mounted on roller shoulder6comprised in stepped hub110.

TheFIG. 6variant includes an added seat89driven onto a stepped hub110. The balance spring collet70is also driven onto stepped shoulder110, in axial abutment on added seat89which in turn abuts on balance hub20. This hub20is held on the opposite side by a sharp rivet edge54, as in theFIG. 1version. An added roller sleeve60, including a conventional large roller61and conventional small roller63, is driven onto stepped hub110, abutting on a shoulder face112.

InFIG. 7, staff1is in three parts and includes an added seat89, intended to be driven onto a rectilinear shoulder113comprised in a rectilinear arbour111on either side of a balance2, mounted on main shoulder5of rectilinear shoulder113; said added seat89includes a first lateral bearing surface81and a second lateral bearing surface82, and a spacer ring208forming an axial stop member for a roller sleeve60mounted on roller shoulder6of rectilinear shoulder113.

TheFIG. 7variant concerns a staff1including a smooth, rectilinear arbour11, onto which the following are driven: collet70, in axial abutment on added seat89, which is in turn in axial abutment on hub20, which is in axial abutment on a spacer ring208with an added roller sleeve60, including a conventional large roller61and a conventional small roller63, carrying impulse pin62and notch64.

InFIG. 8, staff1is in two parts and includes a spacer sleeve111between balance spring collet7and roller shoulder6, the spacer sleeve111including a collar forming the support plate and including main shoulder65and first lateral bearing surface81, the spacer sleeve being driven onto a rectilinear shoulder113comprised in a rectilinear arbour11between main shoulder5and collet shoulder7, said added seat89further including a second lateral bearing surface82, and spacer ring111forming an axial stop member for a roller sleeve60mounted on roller shoulder6.

TheFIG. 8variant concerns a staff1including a smooth, rectilinear arbour11, onto which collet70is driven, in axial abutment on spacer sleeve111. This spacer sleeve111includes, underneath a collar forming a seat, the main shoulder65radially supporting hub20, and a first lateral bearing surface81for the axial abutment of hub20, on the opposite side to collet70. Sleeve111is in axial abutment on an added roller sleeve60, including a conventional large roller61and a conventional small roller63, which carry impulse pin61and notch64.

An advantageous variant ofFIG. 8consists in fixing pin62to balance20which means omitting large roller61and saving axial space height-wise, spacer sleeve111then abutting directly on a sleeve60limited to the small roller63provided with notch64.

InFIG. 9, staff1is in three parts and includes, driven side by side onto a rectilinear shoulder113comprised in a rectilinear arbour11, an added seat89, which includes a first lateral bearing surface81and a second lateral bearing surface82, and a spacer sleeve111carrying main shoulder65, said spacer sleeve111forming an axial stop member for a roller sleeve60mounted on roller shoulder6.

TheFIG. 9variant concerns a staff1including a smooth, rectilinear arbour11, onto which there are driven: collet70, in axial abutment on an added seat89, in axial abutment on a spacer sleeve111. Added seat89includes the first lateral bearing surface81for the axial abutment of hub20on the opposite side to collet70. Sleeve111includes main shoulder65, radially supporting hub20, and is in axial abutment on an added roller sleeve60, including a conventional large roller61and a conventional small roller63, carrying impulse pin62and notch64.

TheFIG. 11variant illustrates a version close to that ofFIG. 1, but wherein sleeve60is incorporated in the actual staff. Only notch64remains. The stepped single-piece arbour110includes a collar119, which has a cylindrical shoulder65for housing hub20, adjacent to a first lateral bearing surface81of the hub, and which faces notch64arranged at the foot of arbour110. The other face of collar119includes a second lateral surface82for the axial abutment of collet70, centred on a cylindrical shoulder7of arbour110. Hub20carries pin62, which cooperates with horns202of the inverted pallets, whereas dart203cooperates with notch64.

Preferably, to facilitate assembly, the maximum diameter of the roller centring shoulder6is less than or equal to the minimum diameter of main shoulder5, and arbour1includes a lateral stop surface9whose diametral dimensions are smaller than or equal to that of main shoulder5, for receiving in abutment a balance roller60mounted on roller shoulder6.

Naturally, the different variants illustrated are suited to holding hub20in place using sharp rivet edges, by local deformation of a roller sleeve60, or of a collar67, or of a stepped hub110, or of a spacer sleeve111, this securing method being shown only inFIGS. 1 and 4for the sake of clarity. Preferably, the components concerned include, in the bare state, a lip extending parallel to axis D, intended to form this sharp rivet edge. Thus, in a particular embodiment of staff1, one of its components includes a lip53of small cross-section to form a sharp rivet edge54locking a hub20of a balance2mounted on main shoulder5or65depending on the case.

The invention also concerns, inFIG. 1, an equipped staff1E comprising a staff1which includes a roller sleeve60carrying at least one roller notch and is intended to be driven onto the roller shoulder6comprised in the stepped hub110, said roller60including a first lateral bearing surface66forming a stop member for a balance2to be mounted on main shoulder5comprised in collar119of stepped hub110.

The invention further concerns, forFIG. 1, an equipped timepiece balance10including a bare balance2whose hub20is mounted on an equipped staff1E of this type. Hub20is mounted via a bore23comprised therein onto main shoulder5, abutting via a first bearing surface21on the first lateral bearing surface81and held, on a second face axially opposite the first bearing face21, either by a sharp rivet edge54derived from the local deformation of a lip53of staff1, or by the irreversible fixing of staff1onto hub20in a fixing area. This equipped balance10includes an impulse pin62and at least one roller notch64, roller pin62being mounted on hub20, or on a roller sleeve60carrying at least one roller notch64and driven onto roller shoulder6. Sleeve60is mounted after balance2has been inserted between the first lateral bearing surface81and sharp rivet edge24or the fixing area.

The invention further concerns an equipped timepiece balance10including a bare balance2whose hub20is mounted on a staff1of this type. Hub20is mounted, via a bore comprised therein, and driven onto main shoulder5, abutting via a first bearing face21on the first lateral bearing surface81of seat8. In the preferred variant ofFIG. 1, hub20is held, on a second face axially opposite the first bearing face21, either by a sharp rivet edge54derived from the local deformation of a lip53of staff1, or by the irreversible fixing of staff1onto hub20in a fixing area.

This equipped balance10includes an impulse pin62and a roller notch64, roller pin62being mounted on hub20, either on a roller sleeve60driven onto a roller shoulder6, and roller notch64being arranged on staff1, or on a roller sleeve60driven onto roller shoulder6.

Preferably, staff1has a lateral stop surface9, which projects axially on pivot axis D relative to sharp rivet edge54or to the fixing area, for receiving in axial abutment a balance roller sleeve60, or a large roller61comprised in said sleeve60clamped onto roller shoulder6, so as to keep roller sleeve60at a distance from a balance2, mounted on main shoulder5and held in abutment on first lateral surface81.

In a particular embodiment, hub20is secured by irreversible welding, or brazing or bonding to staff1.

The invention further concerns a sprung balance assembly100including an equipped balance10of this type, comprising an impulse pin62and a roller notch64. The assembly includes, clamped onto staff1and in abutment on the second lateral surface82or68, a balance spring collet70, to which at least one balance spring71is attached.

The invention further concerns a timepiece combined unit200including a sprung balance assembly100of this type, and including an equipped balance10of this type carrying an impulse pin62and a roller notch64and further including pallets201arranged to cooperate with the impulse pin62and roller notch64. Pallets201are pivotally mounted about a pallet axis DA parallel to pivot axis D of staff1and include horns202arranged to cooperate with impulse pin62as closely as possible to main shoulder5, and a dart203arranged to cooperate with roller notch64as far away as possible from main shoulder5.

Preferably, pallets201include a lever304, which may or may not be integral with pivot205defining the pallet axis DA, lever204carrying the dart203in the alignment thereof, and carrying an added set of horns202in a plane substantially parallel to a plane defined by lever204and dart203.

The invention also concerns a timepiece movement300including at least one combined unit200of this type; it includes a bottom plate301carrying a first pallet stone306and a pallet cock302carrying a second pallet stone307, pallets201being pivotally guided between said pallet stones306,307. Bottom plate301carries a first balance shock absorber guide means308and movement300includes a balance bar303carrying a second balance shock absorber guide means309. The sprung balance assembly100is guided between these shock absorber guide means308,309, and dart203is closer than horns202to whichever shock absorber guide means308,309is farthest from balance spring71.

It is clear that the relative assembly of the dart and horns according to the invention, wherein the horns are mounted off-centre, in a parallel plane to the plane of the fork which carries the dart, is the reverse of the conventional assembly where the dart is inserted parallel to the fork carrying the horns in the same plane as said fork.

The invention also concerns a timepiece1000including at least one such timepiece movement300.

The relative arrangements for holding the balance felloe, by the seat as arranged inFIG. 1or6to9, or by the rollers ofFIGS. 2 to 4, allow the fixing and positioning system to be inverted by 180° with respect to the prior art. Without changing the position of the bars, it is therefore possible to increase the safety devices, particularly between the balance and the oscillating weight, without increasing the height of the movement. To achieve the object of poising the settings and increasing the security devices, between the large roller and the pallet lever, between the pin and the dart, and between the dart and the bottom plate, in addition to inverting the abutment of the balance on its staff, the relative positions of the dart and horns on the pallets must also be inverted. This combination alone allows the relative positions of the other components of the movement: bars, oscillating weight, date disc, incabloc system, to be maintained.

The invention has the advantage of providing an interchangeable set solution, i.e. the new pallets, which are inverted with respect to the conventional position, and the balance according to the invention, may be mounted in a movement which it is proposed to improve, without thereby modifying other components. This notion of interchangeability is economically very important.

The invention provides an economical solution to controlling the height of the movement, while ensuring high safety and setting values, since it only requires action on two components: the balance staff and the pallets.

The invention therefore facilitates the production of ultra-flat movements, with components that are as rigid as those in conventional movements, and without any risk during operation.