BRAKE SPRING FOR CARRIER SHAFT OF A DISPLAY, CLOCK MOVEMENT WITH THIS BRAKE SPRING AND INSTALLATION METHOD OF THIS BRAKE SPRING

Description

Technical field of the invention

[0001] The invention relates to the field of watchmaking, and relates in particular to a brake spring for a shaft carrying a display, a watch movement comprising said brake spring and a method of installing said brake spring. Technological background

[0002] In an analog watch, information about the current time is indicated by displays, such as hands, discs, or other indicating elements. Displays can also indicate other types of information, such as a power reserve, a date, etc.

[0003] To avoid damaging the watch movement or impacting the accuracy of the information it delivers, the displays must not come into contact with any obstacle during their movement. Such an obstacle may be formed, for example, by the glass, the dial, another display, or a component of the watch movement.

[0004] Several factors can give rise to such a situation, such as the play of the shaft which carries the displays, the inclination of said shaft due to the location of the holes made in a plate or a bridge in which it is engaged, the play in the pivots which guide said shaft, the tolerances of flatness and perpendicularity of the displays driven onto said shaft, etc.

[0005] Solutions have been developed over many years to ensure proper positioning of the display support shaft to avoid the aforementioned drawbacks.

[0006] In particular, a known solution consists of arranging a clinker spring on the shaft carrying the displays in order to generate a friction torque making it possible to control the position of said shaft. However, the intensity of the friction torque is complex to control, insofar as it depends on the thickness of said clinker spring, its curvature or even the intrinsic characteristics of the material from which it is made, and directly influences the efficiency of the watch movement. Document EP 2 977 829 A1 shows a braking surface which comprises at least one shoe subjected to the action of at least one first elastic return means, in one piece with a shaft or respectively a wheel, and arranged to exert a radial force relative to said pivot axis on a second surface or respectively a first surface.

[0007] In addition to the position of the carrier shaft, its movement must be controlled in order to avoid display fluttering due to angular play of the gears driving the carrier shaft. Summary of the invention

[0008] The invention solves the aforementioned drawbacks by proposing a solution making it possible to control the position of a shaft carrying a display in order to avoid any collision of said display with an obstacle.

[0009] More particularly, controlling the position of the shaft carrying a display implies controlling the position of the inclination of said shaft and the position in all directions.

[0010] Another objective of the invention is to provide a brake spring which is easy to install within a watch movement.

[0011] To this end, the present invention relates to a brake spring intended to apply a radial force against a shaft carrying a display of a watch. The brake spring comprises an elastic blade, an elastic casing member adapted to be fixed to a hooking member of a structure of a watch movement, and a retaining element of the elastic blade configured to cooperate with said elastic blade, so as to hold it in a first position, said elastic blade being able to be released from said retaining element so as to occupy a second position under the effect of an elastic return force, in which it is able to apply a resultant radial force against a shaft carrying a display.

[0012] Thanks to these characteristics, the brake spring applies a controlled braking torque to the shaft carrying a display, so as to prevent the display from floating and to guarantee adequate positioning of the display to avoid any contact with an obstacle, while minimizing the drop in performance of the watch movement.

[0013] Advantageously, the brake spring can be easily attached to the watch movement, thanks to the elastic casing member and the elastic blade retaining element.

[0014] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in any technically possible combination.

[0015] In particular embodiments, the elastic fitting member comprises a jaw formed by two parts defining a housing and each extending between a first end by which said parts are connected and form a bottom of the housing, and a second end by which they form an opening of said housing.

[0016] In particular embodiments, at least one of the parts is configured so that the housing comprises a narrow portion at its opening, adapted to receive the hooking member in abutment so as to fix said brake spring to the structure of a watch movement.

[0017] In particular embodiments, the opening is flared.

[0018] In particular embodiments, the elastic blade extends from the first end of one of the jaw portions and opposite the jaw opening.

[0019] In particular embodiments, the elastic blade comprises a proximal portion by which it is connected to the jaw, a distal portion, by which it cooperates with the retaining element when it occupies the first position, and by which it is intended to apply a radial force against the shaft carrying a display when it occupies the second position, the proximal and distal portions being connected to each other by an intermediate portion extending opposite the opening.

[0020] In particular embodiments, the elastic blade and the retaining element are arranged on either side of the jaw, respectively on each of the parts of the latter.

[0021] In particular embodiments, the retaining element is formed by a hook configured to cooperate with the free end of the elastic blade.

[0022] According to another aspect, the present invention relates to a watch movement comprising a brake spring as described previously, and a structure comprising a hooking member with which the elastic casing member cooperates so as to fix the brake spring to said structure without a degree of freedom at least when the elastic blade occupies the second position.

[0023] In particular embodiments, the structure comprises a through orifice arranged to open opposite the elastic blade when it occupies the first position.

[0024] In particular embodiments, the attachment member is formed by two projecting parts extending perpendicularly to a plane formed by the structure.

[0025] In particular embodiments, the projecting parts each comprise, at their free end, a radial collar arranged opposite the brake spring.

[0026] In particular embodiments, one of the projecting parts is arranged in abutment against the parts of the jaw, at the level of the narrow portion, the other projecting part being arranged in abutment against the bottom of the housing.

[0027] Yet another aspect of the invention relates to a method of installing a brake spring as previously described on a structure of a watch movement as previously described, comprising the following successive steps: fixing the brake spring to the structure of the watch movement; holding the elastic blade in a first position, in which said elastic blade is arranged so as to cooperate with the retaining element; engaging the shaft through an opening in the structure; releasing the elastic blade from the retaining element so that said elastic blade occupies a second position in which it applies a radial force against a shaft carrying a display of the watch movement.

[0028] In particular embodiments, the fixing step comprises a positioning operation in which the brake spring is arranged against the structure of the watch movement and a casing operation in which the brake spring is moved against said structure so that the elastic casing member cooperates by elastic casing with the attachment member.

[0029] In particular embodiments, the release step is carried out by introducing a tool through a through orifice made in the structure of the watch movement, opening opposite the elastic blade, so that said tool exerts a force on said blade tending to move it away from the retaining element. Brief description of the figures

[0030] Other characteristics and advantages of the invention will appear on reading the following detailed description given by way of non-limiting example, with reference to the appended drawings in which: there Figure 1 represents a perspective view of a brake spring according to a preferred embodiment of the invention; figures 2 to 4 represent a perspective view of the brake spring of the Figure 1 at different stages of installation of the brake spring on a structure of a watch movement. Detailed description of the invention

[0031] There Figure 1shows a preferred example of embodiment of a brake spring 10 according to the invention, intended to be fixed to a structure 21 of a watch movement 20 so as to apply a radial force against a shaft 22 carrying a display of a watch. Such a display may consist of a hand, a disc, or other indicator members.

[0032] Such a structure 21 may be formed by a bridge, by a holding plate or by a bottom plate of the watch movement 20. The structure 21 comprises an opening through which the shaft 22 is engaged, in a manner known per se to those skilled in the art.

[0033] The brake spring 10 comprises an elastic blade 11 connected to an elastic casing member 12 adapted to be fixed to a hooking member 23 of the structure 21 of the watch movement 20.

[0034] The elastic blade 11 is configured to cooperate, by a free end, with a retaining element 13 connected to the elastic fitting member 12, so as to maintain said elastic blade 11 in a first position, as visible in the Figure 3 In this first position, the elastic blade 11 is constrained by the retaining element 13, so that its freedom of movement is low, or even zero.

[0035] When the elastic blade 11 is in this first position, it is possible to install the brake spring 10 without risk of conflict between the shaft 22 and the elastic blade 11.

[0036] The elastic blade 11 can be released from said retaining element 13, as described below in detail, so as to occupy, under the effect of an elastic restoring force, a second position visible on the Figure 4, in which it is capable of applying a radial force against a shaft 22. This radial force results from the elastic return force of the elastic blade 11 and generates friction at the origin of a braking torque of the shaft 22 carrying the display, in a manner well known as such by those skilled in the art.

[0037] As shown by the figures 1 to 4 , the elastic fitting member 12 comprises a jaw formed by two parts 121 and 122 each extending between a first end by which said parts 121 and 122 are connected to each other and form a bottom 123 of a housing 124, and a second end by which they form an opening 125 of said housing 124. The housing 124 is defined between the parts 121 and 122 of the jaw and is intended to receive the hooking member 23 after its introduction through the opening 125.

[0038] The jaw has a capacity for elastic deformation insofar as the parts 121 and 122 have a degree of rotational mobility relative to each other so as to vary the dimension of the opening 125 of the housing 124, that is to say the distance separating the second ends of said two parts 121 and 122. Such an elastic capacity allows the fixing of the brake spring 10 on the structure 21 of the watch movement 20, by elastic fitting, as described below.

[0039] The opening 125 of the housing 124 can advantageously be flared, so as to facilitate the introduction of the attachment member 23 through said opening 125.

[0040] Furthermore, at least one of the parts 121 or 122 can be configured so that the housing 124 comprises a narrow portion 126, between the opening 125 and the bottom 123, adapted to receive the hooking member 23 in abutment when the jaw is fixed to said hooking member 23, as shown in figures 2 to 4 . By "narrow portion" is meant a portion of the housing 124 in which the distance separating the parts 121 and 122 is reduced, as shown in the figures 1 to 4 .

[0041] Thus, in the preferred embodiment of the invention, the jaw portions 121 and 122 are configured such that, from the bottom 123 towards the opening 125, the distance separating them increases to a maximum, then decreases to a minimum corresponding to the narrow portion 126, then increases again.

[0042] It should be noted that, due to these features, in the preferred embodiment shown in the figures 1 to 4, the housing 124 extends substantially along a longitudinal axis.

[0043] It should also be noted that, in other embodiments of the invention, the shape of the housing 124 defined by the jaw may be different from that described previously.

[0044] Advantageously, the housing 124 may comprise a hollow 127, at the level of the bottom 123, in order to house the attachment member 23. More particularly, the shape of the hollow 127 may correspond to that of a part of the periphery of the attachment member 23, so that the hollow 127 matches the periphery of the attachment member 23 to ensure that it is held in position in the jaw.

[0045] When the brake spring 10 is fixed to the structure 21 of the watch movement 20, the hooking member 23 is then in abutment against the bottom 123, or against the hollow 127, and against the narrow portion 126 of the housing 124, as visible in the figures 2 to 4 .

[0046] Thus, when the jaw cooperates by elastic fitting with the hooking member 23, the brake spring 10 is linked to the structure 21 of the watch movement 20 without any degree of freedom.

[0047] Advantageously, thanks to the particular profile of the jaw, the cooperation by elastic fitting is reversible, so that it is possible to remove the brake spring 10 from the structure 21 of the watch movement 20, for example to carry out a maintenance operation on said watch movement 20.

[0048] In the preferred embodiment of the invention, as shown in the figures 1 to 4 , the attachment member 23 is formed by two projecting pieces extending perpendicularly relative to a plane formed by the structure 21.

[0049] Such protruding parts can be formed by tenons or pins.

[0050] The projecting parts each comprise, at their free end, a radial collar 230 arranged opposite each of the parts 121 and 122 of the jaw when the brake spring 10 is fixed to said structure 21. This collar 230 advantageously ensures the blocking of any translational mobility of the brake spring 10 along an axis perpendicular to the plane formed by the structure 21, apart from mechanical clearances. Thus, the collars 230 prevent the brake spring 10 from becoming detached from the projecting parts in the event of a possible shock to the watch.

[0051] This feature helps to ensure that the brake spring 10 is held in position on the watch movement 20.

[0052] The elastic blade 11 and the retaining element 13 are preferably arranged on either side of the elastic fitting member 12, as shown in the figures 1 to 4 in a preferred embodiment of the present invention.

[0053] The elastic blade 11 extends from the first end of one of the parts 122 of the jaw and opposite the opening 125 of the housing 124 of the jaw, as visible in the figures 1 to 4 .

[0054] More specifically, in the preferred embodiment of the invention, the elastic blade 11 comprises a proximal portion 110 by which it is connected to the jaw and a distal portion 111, by which it cooperates with the retaining element 13 when it occupies the first position, and by which it is intended to apply a radial force against the shaft 22 carrying the display when it occupies the second position. The proximal 110 and distal 111 portions are connected to each other by an intermediate portion 112 extending opposite the opening 125.

[0055] The proximal 110, intermediate 112 and distal 111 portions are bent relative to each other so that the distal 111 and proximal 110 portions are substantially parallel to each other when the elastic blade 11 is in the first position.

[0056] Thanks to this particular shape of the elastic blade 11, the force applied against the shaft 22 has a main component whose direction is perpendicular to the longitudinal axis along which the housing 124 of the jaw extends, and coincides substantially with the first end of the parts 121 and 122, which helps to guarantee the good holding of the fixing of the jaw on the structure 21.

[0057] The retaining element 13 is preferably formed by a hook configured to cooperate with the free end of the elastic blade 11. It is therefore understood that the hook extends from the first end of one of the parts 121, opposite the proximal portion 110 of the elastic blade 11.

[0058] The structure 21 advantageously comprises a through orifice 210, for example of oblong shape, arranged to open opposite the elastic blade 11 when it is in the first position. Such an arrangement makes it possible to exert a force on the elastic blade 11 tending to release it from the hook with a tool engaged through said orifice 210, as described in more detail below.

[0059] The present invention also relates, according to another aspect, to a method of installing the brake spring 10 on the structure 21 of the watch movement 20, successively comprising the steps of: fixing the brake spring 10 on the structure 21 of the watch movement 20; this step is carried out by cooperation by elastic fitting of the jaw and the projecting parts by sliding said brake spring 10 against the structure 21 in the direction of the arrow shown in the Figure 2 ; holding the elastic blade 11 in a first position in which said elastic blade 11 is arranged so as to cooperate with the retaining element 13; engaging the shaft 22 through an opening in the structure 21; these steps of holding the elastic blade 11 and engaging the shaft 22 are illustrated in the Figure 3 ; release of the elastic blade 11 from the stress exerted by the retaining element 13, so that said elastic blade 11, under the effect of an elastic restoring force, occupies the second position in which it applies a radial force against the shaft 22, as shown in Figure 4 .

[0060] More specifically, the fixing step comprises a positioning operation in which the brake spring 10 is arranged against the structure 21 of the watch movement 20, as shown in the Figure 2 , one of the projecting parts being arranged in the housing 124 formed by the jaw and the other being arranged between the intermediate portion 112 of the elastic blade 11 and the opening 125 of the housing 124 of the jaw.

[0061] The fixing step then comprises a fitting operation in which the brake spring 10 is moved in translation along the longitudinal axis of the housing 124 so that one of the projecting parts is arranged against the bottom 123 of the housing 124 and the other is arranged against the narrow portion 126 thereof.

[0062] The release step is carried out by introducing a tool through the through orifice 210 made in the structure 21 of the watch movement 20, and by exerting with said tool a force on the elastic blade 11 tending to release it from the retaining element 13.

[0063] The brake spring 10 can be produced by any suitable manufacturing method, such as machining, casting or additive manufacturing.

[0064] Advantageously, the brake spring 10 is preferably produced by the LIGA method (from the German “Röntgenlithographie, Galvanoformung, Abformung” meaning in French “lithography, galvanization, forming”).

[0065] More generally, it should be noted that the methods of implementation and embodiment considered above have been described as non-limiting examples, and that other variants are consequently conceivable.

[0066] In particular, the arrangement of the elastic blade 11 relative to the elastic fitting member 12 could be different from that described above and shown in the figures 1 to 4 .

Claims

1. Brake spring (10) intended to apply a radial force against a supporting arbor (22) of a display of a watch including an elastic strip (11), an elastic casing organ (12) adapted to be fastened to an attachment organ (23) of a structure (21) of a horological movement (20), and a retaining element (13) of the elastic strip (11) configured to cooperate with said elastic strip (11), so as to hold it in a first position, said elastic strip (11) being capable of being released from said retaining element (13) so as to occupy a second position under the effect of an elastic return force, wherein it is capable of applying a resulting radial force against the supporting arbor (22) of a display.

2. Brake spring (10) according to claim 1, wherein the elastic casing organ (12) includes jaws formed by two portions (121, 122) defining a bed (124) and each extending between a first end by which said portions (121, 122) are connected and form a back (123) of the bed (124), and a second end by which they form an opening (125) of said bed (124).

3. Brake spring (10) according to claim 2, wherein at least one of the portions (121, 122) is configured so that the bed (124) includes a narrow portion (126) at its opening (125), adapted to receive the attachment organ (23) in abutment so as to fasten said brake spring (10) to the structure (21) of a horological movement (20).

4. Brake spring (10) according to one of claims 2 or 3, wherein the opening (125) is flared.

5. Brake spring (10) according to one of claims 2 to 4, wherein the elastic strip (11) extends from the first end of one of the portions (121, 122) of the jaws and opposite the opening (125) of the jaws.

6. Brake spring (10) according to claim 5, wherein the elastic strip (11) comprises a proximal portion (110) by which it is connected to the jaws, a distal portion (111), by which it cooperates with the retaining element (13) when it occupies the first position, and by which it is intended to apply a radial load against the arbor (22) when it occupies the second position, the proximal (110) and distal portions (111) being connected to one another by an intermediate portion (112) extending opposite the opening (125).

7. Brake spring (10) according to claim 5 or 6, wherein the elastic strip (11) and the retaining element (13) are arranged on either side of the jaws, respectively on each of the portions (121, 122) of the latter.

8. Brake spring (10) according to one of claims 1 to 7, wherein the retaining element (13) is formed by a hook configured to cooperate with the free end of the elastic strip (11).

9. Horological movement (20) characterised in that it includes a brake spring (10) according to one of claims 1 to 8, and a structure (21) comprising an attachment organ (23) with which the elastic casing organ (12) cooperates so as to fasten the brake spring (10) to said structure (21) without degree of freedom at least when the elastic strip (11) occupies the second position.

10. Horological movement (20) according to claim 9, wherein the structure (21) comprises a through-hole (210) arranged to open opposite the elastic strip (11) when it occupies the first position.

11. Horological movement (20) according to one of claims 9 or 10, wherein the attachment organ (23) includes, at its free end, a radial flange (230) arranged opposite the brake spring (10).

12. Horological movement (20) according to one of claims 9 to 11, wherein the attachment organ (23) is formed by two protruding parts extending perpendicularly in relation to a plane formed by the structure (21).

13. Horological movement (20) according to claim 12, comprising a brake spring (10) according to claim 3, wherein one of the protruding parts is arranged in abutment against the portions (121, 122) of the jaws, at the narrow portion (126), the other protruding part being arranged in abutment against the back (123) of the bed (124).

14. Method for installing a brake spring (10) according to one of claims 1 to 8 on a structure (21) of a horological movement (20) according to one of claims 9 to 13, characterised in that it includes the following successive steps of: - fastening the brake spring (10) on the structure (21) of the horological movement (20); - holding the elastic strip (11) in a first position, wherein said elastic strip (11) is arranged so as to cooperate with the retaining element (13); - engaging the arbor (22) through an opening of the structure (21); - releasing the elastic strip (11) from the retaining element (13) so that said elastic strip (11) occupies a second position wherein it applies a radial force against a supporting the arbor (22) of a display of the horological movement (20).

15. Method according to claim 14, wherein the fastening step includes a positioning operation wherein the brake spring (10) is arranged against the structure (21) of the horological movement (20) and a casing operation wherein the brake spring (10) is moved against said structure (21) so that the elastic casing organ (12) cooperates by elastic casing with the attachment organ (23).

16. Method according to one of claims 13 to 15, wherein the release step is performed by inserting a tool through a through-hole (210) made in the structure (21) of the horological movement (20), opening opposite the elastic strip (11), in order that said tool exerts a load on said strip tending to move it apart from the retaining element (13).