Brake spring for a support arbor of a display device, timepiece movement comprising a brake spring and method of mounting a brake spring

Abstract

The invention relates to a brake spring (10) intended to exert a radial force against a support arbor (22) of a display device of a watch, comprising: an elastic strip (11); an elastic sheathing mechanism (12) adapted to fasten to an attachment mechanism (23) of a structure (21) of a timepiece movement (20); and a retaining element (13) of the elastic strip (11), configured to cooperate with said elastic strip (11) to retain it in a first position, said elastic strip (11) being releasable from said retaining element (13) to occupy a second position under the effect of an elastic return force, in which the elastic strip (11) can exert a resulting radial force against the arbor (22).

Description

TECHNICAL FIELD

[0001] The present invention belongs to the field of timepieces and in particular relates to a braking spring for a support arbor of a display device, to a timepiece movement comprising said braking spring and to a method for mounting said braking spring. BACKGROUND

[0002] In a hands-displayed watch, information related to the current time is indicated by display devices such as hands, dials or other indicator mechanisms. The display devices can also indicate other types of information such as power reserve, date, etc.

[0003] In order not to damage the timepiece movement or to affect the accuracy of the information transmitted by it, the display devices must not come into contact with obstacles during their travel. Such obstacles can be formed, for example, by the watch glass, the dial, another display device or a component of the timepiece movement.

[0004] Various factors can lead to such situations, such as the play of the arbor supporting the display device, the inclination of the arbor due to the position of the hole in which it is engaged, made in the main clamping plate or pont, the play in the pivot guiding the arbor, the flatness and perpendicularity tolerances of the display device driven on the arbor, etc.

[0005] Solutions have been developed over the years to ensure the proper positioning of the support arbor of the display device in order to prevent the above-mentioned defects.

[0006] In particular, a known solution consists in arranging a metal foil spring on the support arbor of the display device to generate a friction torque for controlling the position of the arbor. However, controlling the strength of the friction torque is complex since it depends on the thickness of the metal foil spring, its curvature or also on the intrinsic characteristics of the material constituting this metal foil spring and this directly affects the efficiency of the timepiece movement.

[0007] In addition to the position of the support arbor, its movement should also be controlled in order to prevent the display device from floating due to the angular play of the gear driving the support arbor. SUMMARY

[0008] The present invention solves the above-mentioned defects by proposing a solution for controlling the position of the support arbor of a display device in order to prevent any collision of the display device with obstacles.

[0009] More particularly, controlling the position of the support arbor of the display device means controlling the position of the inclination of the arbor and the position in all directions.

[0010] Another object of the present invention is to provide a braking spring whose mounting within a timepiece movement is easy.

[0011] To this end, the invention relates to a braking spring intended to exert a radial force against a support arbor of a display device of a watch. The braking spring comprises an elastic strip, an elastic sheathing organ adapted to be fastened to an attachment organ of a structure of a timepiece movement, and a retaining element of the elastic strip configured to cooperate with said elastic strip to retain the elastic strip in a first position, said elastic strip being releasable from said retaining element to occupy a second position under the effect of an elastic return force, in which the elastic strip is intended to exert a resulting radial force against the support arbor of the display device.

[0012] Thanks to these features, the braking spring exerts a controlled braking torque on the support arbor of the display device, thereby avoiding the floating of the display device and guaranteeing the proper positioning of the display device to prevent any contact with obstacles, while minimizing the reduction of the efficiency of the timepiece movement.

[0013] Advantageously, thanks to the elastic sheathing organ and the retaining element of the elastic strip, the braking spring can be easily fastened to the timepiece movement.

[0014] In particular embodiments, the invention can also include one or more of the following features, taken alone or according to any technically possible combination.

[0015] In particular embodiments, the elastic sheathing organ comprises a pincer formed of two parts defining a housing and each extending between a first end and a second end, said parts being connected by the first end and forming a rear part of the housing, said parts forming an opening of said housing by the second end.

[0016] In particular embodiments, at least one of said parts is configured so that the housing comprises a narrow part at its opening, adapted to receive an abutment attachment organ in order to fasten said braking spring to a structure of the timepiece movement.

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

[0018] In particular embodiments, the elastic strip extends from the first end of one of the parts of the pincer and opposite the opening of the pincer.

[0019] In particular embodiments, the elastic strip comprises a proximal part and a distal part, the elastic strip being connected to the pincer by the proximal part; the elastic strip cooperating with the retaining element by the distal part when it occupies the first position, and the elastic strip being intended to exert a radial load against the support arbor of the display device by the distal part when it occupies the second position; the proximal part and the distal part being connected to each other by an intermediate part extending opposite the opening.

[0020] In particular embodiments, the elastic strip and the retaining element are arranged on either side of the pincer, on each of the portions of the pincer respectively.

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

[0022] According to another aspect, the application relates to a timepiece movement comprising a braking spring as described above, and a structure comprising an attachment mechanism with which the elastic sheathing mechanism cooperates in order to fasten the braking spring to said structure without degrees of freedom at least when the elastic strip occupies the second position.

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

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

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

[0026] In particular embodiments, one of the projecting parts is arranged in abutment against the portion of the pincer at the narrow portion, the other projecting part being arranged in abutment against the rear portion of the slot.

[0027] Yet another aspect of the application relates to a method for mounting a braking spring as described above on a structure of a timepiece movement as described above, said method comprising the following sequential steps:

[0028] - fastening the braking spring on the structure of the timepiece movement;

[0029] - retaining the elastic strip in the first position, in which said elastic strip is arranged to cooperate with the retaining element;

[0030] - engaging the mandrel through the opening of the structure;

[0031] - releasing the elastic strip from the retaining element so that said elastic strip occupies the second position, in which the elastic strip exerts a radial force against the support mandrel of the display device of the timepiece movement.

[0032] In particular embodiments, the fastening step comprises a positioning operation, in which the braking spring is arranged against the structure of the timepiece movement, and a sheathing operation, in which the braking spring is moved against said structure so that the elastic sheathing mechanism cooperates with the attachment mechanism by elastic sheathing.

[0033] In a particular embodiment, the execution of the releasing step is carried out by inserting a tool through a through hole made in the structure of the timepiece movement, which through hole is opposite the opening of the elastic band, so that said tool exerts on said band a load tending to move the band away from the retaining element. BRIEF DESCRIPTION OF DRAWINGS

[0034] Other features and advantages of the application will become apparent on reading the following detailed description, given by way of non-limiting example, with reference to the appended drawings, in which:

[0035] - Figure 1 a perspective view of a braking spring according to a preferred embodiment of the application is shown;

[0036] - Figures 2 to 4 a perspective view of a braking spring according to a preferred embodiment of the application is shown; Figure 1 a perspective view of various steps of the installation of a braking spring on a structure of a timepiece movement. DETAILED DESCRIPTION

[0037] Figure 1 A preferred embodiment of a braking spring 10 according to the application is shown, which braking spring 10 is intended to be fastened to a structure 21 of a timepiece movement 20, so as to exert a radial force against a support arbor 22 of a display device of the watch. Such a display device can comprise a hand, a dial or other indicator mechanism.

[0038] Such a structure 21 can be formed by a bridge, a retaining plate or a main clamping plate of the timepiece movement 20. The structure 21 comprises an opening through which the arbor 22 is engaged in a manner known to the person skilled in the art.

[0039] The braking spring 10 comprises an elastic band 11 connected to an elastic sleeve mechanism 12, which elastic sleeve mechanism 12 is adapted to be fastened to an attachment mechanism 23 of the structure 21 of the timepiece movement 20.

[0040] As can be seen in Figure 3 The elastic band 11 is configured to cooperate, by a free end, with a retaining element 13 connected to the elastic sleeve mechanism 12, so as to retain said elastic band 11 in a first position. In this first position, the elastic band 11 is constrained by the retaining element 13, so that its degree of freedom of movement is low, or even zero.

[0041] When the elastic band 11 is in this first position, the braking spring 10 can be installed without risk of collision between the arbor 22 and the elastic band 11.

[0042] As described in detail hereinafter, the elastic band 11 can be released from said retaining element 13, so as to occupy, under the effect of an elastic return force, a second position in which it is free to move. Figure 4A second position can be seen in which the elastic band 11 can exert a radial force against the arbor 22. This radial force results from the elastic return force of the elastic band 11 and generates a friction which, in a manner known to those skilled in the art, causes a braking torque of the support arbor 22 of the display device.

[0043] As Figures 1 to 4 The elastic sleeve mechanism 12 comprises, as shown in

[0044] The pincer has the ability to elastically deform, provided that the portions 121 and 122 have a certain degree of rotational mobility with respect to one another so as to vary the size of the opening 125 of the slot 124 (that is to say, the distance separating the second ends of the two portions 121 and 122). Such an elastic ability makes it possible, as described above, to fasten the braking spring 10 on the structure 21 of the timepiece movement 20 by elastic sleeving.

[0045] The opening 125 of the slot 124 can advantageously be flared so as to facilitate the insertion of the attachment mechanism 23 through said opening 125.

[0046] Furthermore, as shown in Figures 2 to 4 At least one of the portions 121 or 122 can be configured so that the slot 124 comprises, between the opening 125 and the rear portion 123, a narrow portion 126 which is adapted to receive the attachment mechanism 23 abuttingly when the pincer is fastened to said attachment mechanism 23, as shown in Figures 1 to 4 The "narrow portion" means, as shown in

[0047] Thus, in a preferred embodiment of the application, the portions 121 and 122 of the pincer are configured so that, from the rear portion 123 to the opening 125, the distance separating the portions 121 and 122 increases to a maximum value, then decreases to a minimum value corresponding to the narrow portion 126, then increases again.

[0048] It should be noted that, thanks to these features, in the preferred example of embodiment shown in Figures 1 to 4 The slot 124 extends substantially along the longitudinal axis, in the preferred example of embodiment shown in

[0049] It should also be noted that, in other embodiments of the application, the shape of the slot 124 defined by the pincer can be different from that described above.

[0050] Advantageously, the slot 124 can comprise a recess 127 at the rear portion 123 in order to lodge the attachment mechanism 23. More particularly, the shape of the recess 127 can correspond to the shape of a portion of the periphery of the attachment mechanism 23, so that the recess 127 fits the profile of the periphery of the attachment mechanism 23, to guarantee that the attachment mechanism 23 remains in place in the pincer.

[0051] As can be seen in Figures 2 to 4 When the braking spring 10 is fastened to the structure 21 of the timepiece movement 20, the attachment mechanism 23 then abuts against the rear portion 123, or against the recess 127, and against the narrow portion 126 of the slot 124, as can be seen in

[0052] Thus, when the pincer is engaged by elastic fitting with the attachment mechanism 23, the braking spring 10 is linked to the structure 21 of the timepiece movement 20 without degrees of freedom.

[0053] Advantageously, thanks to the particular profile of the pincer, the engagement by elastic fitting is reversible, so that the braking spring 10 can be removed from the structure 21 of the timepiece movement 20, for example in order to perform a maintenance operation of said timepiece movement 20.

[0054] Such as Figures 1 to 4 In a preferred embodiment of the application, the attachment mechanism 23 is formed by two projecting parts extending perpendicularly with respect to the plane formed by the structure 21, as shown in

[0055] Such projecting parts can be formed by posts or pins.

[0056] The projecting parts each comprise, at their free end, a radial flange 230, which is arranged opposite each of the portions 121 and 122 of the pincer when the braking spring 10 is fastened on said structure 21. This flange 230 advantageously makes it possible to ensure locking of any translational mobility of the braking spring 10 along an axis perpendicular to the plane formed by the structure 21, with the exception of mechanical play. Thus, the flange 230 makes it possible to prevent the braking spring 10 from detaching from the projecting parts during possible watch vibrations.

[0057] This feature helps to ensure that the braking spring 10 remains in place on the timepiece movement 20.

[0058] As shown in Figures 1 to 4 In a preferred example of embodiment of the application, the elastic band 11 and the retaining element 13 are preferably arranged on either side of the elastic fitting mechanism 12, as shown in

[0059] As shown in Figures 1 to 4It can be seen that the elastic band 11 extends from the first end of one of the portions 122 of the pincer and opposite the opening 125 of the slot 124 of the pincer.

[0060] More particularly, in the preferred embodiment of the application, the elastic band 11 comprises a proximal portion 110 and a distal portion 111; the elastic band 11 is connected to the pincer by this proximal portion 110; the elastic band 11 cooperates with the retaining element 13 by this distal portion 111 when it occupies the first position, and the elastic band 11 is intended to exert a radial load against the support arbor 22 of the display device by this distal portion 111 when it occupies the second position. The proximal portion 110 and the distal portion 111 are connected to each other by an intermediate portion 112 which extends opposite the opening 125.

[0061] The proximal portion 110, the intermediate portion 112 and the distal portion 111 are curved one with respect to the others so that, when the elastic band 11 is in the first position, the distal portion 111 and the proximal portion 110 are substantially parallel to each other.

[0062] Thanks to the particular shape of the elastic band 11, the force exerted against the arbor 22 has a main component whose direction is perpendicular to the longitudinal axis according to which the slot 124 of the pincer extends, and substantially coincides with the first end of the portions 121 and 122, which contributes to guaranteeing the correct strength with which the pincer is fastened on the structure 21.

[0063] The retaining element 13 is preferably formed by a hook configured to cooperate with the free end of the elastic band 11. It is thus understood that the hook extends from the first end of the portion 121, opposite the proximal portion 110 of the elastic band 11.

[0064] The structure 21 advantageously comprises a through hole 210, for example having an elliptical shape; this through hole 210 is arranged to open opposite the elastic band 11 when the latter is in the first position. Such a layout makes it possible, as described in greater detail below, to exert a load on the elastic band 11 tending to cause it to come out of the hook, with engagement by a tool passing through said hole 210.

[0065] According to another aspect, the application also relates to a method for mounting a brake spring 10 on a structure 21 of a timepiece movement 20, said method comprising in succession the following steps:

[0066] - fastening the brake spring 10 on the structure 21 of the timepiece movement 20; this step is performed by sliding said brake spring 10 against the structure 21 in the direction of the arrows shown in Figure 2 - exerting a radial load against the arbor 22 of the display device by the elastic sleeve of the pincer and of the protruding member;

[0067] - maintaining the elastic band 11 in a first position in which it is arranged in cooperation with the retaining element 13;

[0068] - engaging the mandrel 22 through the opening of the structure 21; these steps of maintaining the elastic band 11 and engaging the mandrel 22 are illustrated in Figure 3 ;

[0069] - releasing the elastic band 11 from the strain exerted by the retaining element 13 so that it occupies a second position under the effect of an elastic return force, as illustrated in Figure 4 , in which the elastic band 11 exerts a radial force against the mandrel 22.

[0070] More particularly, the fastening step comprises a positioning operation in which the detent spring 10 is arranged against the structure 21 of the timepiece movement 20, as illustrated in Figure 2 , one of the protruding parts being arranged in the slot 124 formed by the pincer and the other being arranged between the intermediate portion 112 of the elastic band 11 and the opening 125 of the slot 124 of the pincer.

[0071] The fastening step then comprises a sleeving operation in which the detent spring 10 is moved in translation along the longitudinal axis of the slot 124 so that one of the protruding parts is arranged against the rear portion 123 of the slot 124 and the other is arranged against the narrow portion 126 of the slot 124.

[0072] The release step is performed by inserting a tool through a through hole 210 made in the structure 21 of the timepiece movement 20 and by exerting, with said tool, a load on the elastic band 11 tending to cause it to come out of the retaining element 13.

[0073] The detent spring 10 can be produced by any suitable manufacturing method, such as by machining, by moulding or by additive manufacturing.

[0074] Advantageously, the detent spring 10 is preferably produced by the LIGA (German for “Röntgenlithographie, Galvanoformung, Abformung” meaning “lithography, galvanoplasty, moulding”) method.

[0075] More generally, it should be noted that the embodiments and examples considered above have been described by way of non-limiting example and that other variants are therefore possible.

[0076] In particular, the arrangement of the elastic band 11 relative to the elastic sleeving mechanism 12 can be different from the one described above and illustrated in Figures 1 to 4 .

Claims

1. A brake spring (10) intended to exert a radial force against a support arbor (22) of a display device of a watch, characterized in that, The brake spring (10) comprises an elastic strip (11), an elastic sleeve mechanism (12) adapted to be fastened to an attachment mechanism (23) of a structure (21) of a timepiece movement (20), and a retaining element (13) of the elastic strip (11) configured to cooperate with the elastic strip (11) to retain it in a first position, the elastic strip (11) being releasable from the retaining element (13) to occupy a second position in which it is intended to exert a generated radial force against the support arbor (22) of a display device, under the effect of an elastic return force.

2. The brake spring (10) of claim 1, characterized in that The elastic sleeve mechanism (12) comprises a pincer formed of two parts (121, 122) defining a slot (124) and each extending between a first end and a second end, the parts (121, 122) being connected by the first end and forming a rear portion (123) of the slot (124), the parts (121, 122) forming an opening (125) of the slot (124) by the second end.

3. The brake spring (10) of claim 2, characterized in that At least one of the parts (121, 122) is configured so that the slot (124) comprises a narrow portion (126) at its opening (125) adapted to receive the attachment mechanism (23) in abutment in order to fasten the brake spring (10) to the structure (21) of the timepiece movement (20).

4. The brake spring (10) according to any one of claims 2 or 3, characterized in that The opening (125) is flared.

5. The brake spring (10) according to claim 2 or 3, characterized in that The elastic strip (11) extends from the first end of one of the parts (121, 122) of the pincer and opposite the opening (125) of the pincer.

6. The brake spring (10) of claim 5, characterized in that The elastic strip (11) comprises a proximal portion (110) by which it is connected to the pincer and a distal portion (111) with which it cooperates with the retaining element (13) when the elastic strip (11) occupies a first position and with which it is intended to exert a radial load against the support arbor (22) when the elastic strip (11) occupies a second position; the proximal portion (110) and the distal portion (111) are connected to each other by an intermediate portion (112) extending opposite the opening (125).

7. The brake spring (10) of claim 5, wherein, The elastic strip (11) and the retaining element (13) are arranged on either side of the pincer, respectively on each of the parts (121, 122) of the pincer.

8. The brake spring (10) according to any one of claims 1 to 3, characterized in that The retaining element (13) is formed by a hook configured to cooperate with a free end of the elastic strip (11).

9. A timepiece movement (20), characterized in that, The timepiece movement (20) comprises a braking spring (10) according to any one of claims 1 to 8, and a structure (21) comprising an attachment mechanism (23), the elastic sheathing mechanism (12) cooperating with the attachment mechanism (23) so as to fasten the braking spring (10) to the structure (21) without degrees of freedom at least when the elastic band (11) occupies the second position.

10. A timepiece movement (20) according to claim 9, wherein, The structure (21) comprises a through hole (210) arranged to open opposite the elastic band (11) when the elastic band (11) occupies the first position.

11. A watch movement (20) according to either one of Claims 9 or 10, characterized in that, The attachment mechanism (23) comprises, at its free end, a radial flange (230) arranged opposite the braking spring (10).

12. A timepiece movement (20) according to claim 9 or 10, characterized in that, The attachment mechanism (23) is formed by two projecting parts extending perpendicularly from a plane formed with respect to the structure (21).

13. Timepiece movement (20) according to claim 12, comprising a braking spring (10) according to claim 3, characterized in that, One of the projecting parts is arranged in abutment against the portion (121, 122) of the jaw at the narrow portion (126), the other projecting part being arranged in abutment against the rear portion (123) of the slot (124).

14. A method for mounting a brake spring (10) according to any one of claims 1 to 8 on a structure (21) of a timepiece movement (20) according to any one of claims 9 to 13, characterized in that, The method comprises the following sequential steps: - fastening the braking spring (10) on the structure (21) of the timepiece movement (20); - holding the elastic band (11) in a first position, in which the elastic band (11) is arranged to cooperate with the holding element (13); - engaging the support arbor (22) through the opening of the structure (21); - releasing the elastic band (11) from the holding element (13) so that the elastic band (11) occupies a second position, in which it exerts a radial force against the support arbor (22) of a display device of the timepiece movement (20).

15. The method of claim 14, wherein, The fastening step comprises a positioning operation, in which the braking spring (10) is arranged against the structure (21) of the timepiece movement (20), and a sheathing operation, in which the braking spring (10) is moved against the structure (21) so that the elastic sheathing mechanism (12) cooperates with the attachment mechanism (23) by elastic sheathing.

16. The method according to claim 14 or 15, characterized in that The release step is performed by inserting a tool through a through hole (210) made in the structure (21) of the timepiece movement (20), the through hole (210) opening opposite the elastic band (11) so that the tool exerts a load on the band tending to move the band away from the holding element (13).

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