System for fixing movement of timepiece to element of watchcase

Abstract

The invention provides a system for fixing a movement of a timepiece to an element of a case, comprising at least one clamp, in particular at least two, preferably three or four clamps, for first contacting with the movement and second contacting with the element of the case, the at least one clamp is made of a superelastic alloy and / or a shape memory alloy, in particular a nickel-titanium alloy, such as nitinol.

Description

[0001] The present application is a divisional application of the Chinese patent application No. 201811348780.3, filed on November 13, 2018, entitled “System for fixing a clock movement in a watch case”. TECHNICAL FIELD

[0002] The present invention relates to a system for fixing a clock movement to an element of a watch case. The present invention also relates to a clock unit comprising such a system. The present invention also relates to a clock comprising such a system or such a unit. Finally, the present invention relates to a method of operating such a system or such a unit or such a clock. BACKGROUND

[0003] Generally, two or three case clamps are used to assemble or fix a clock movement within a watch case, in particular within a middle.

[0004] When assembling the movement within the watch case, each case clamp is inserted into a cut-out formed on the inner circumference of the middle and then fixed to the movement by fixing means.

[0005] The cut-out is in particular shaped so that the clamp can generate a suitable pre-stress which can press the movement against the middle of the watch case to meet predetermined criteria. For example, one criterion can be to minimize the range of movement of the movement for a given impact strength and given geometry and material of the clamp, without risking plastic deformation of the clamp.

[0006] Figure 1 And Figure 2 The structure of such a case clamp arrangement is illustrated. At least one clamp 1* is pressed against flat and parallel surfaces 2a*, 3a* associated respectively with a movement 2* and a middle 3* of a watch case 30*. Thus, the clamp 1* elastically deforms when assembling the movement so that the elastic restoring force of the clamp keeps the surface 2b* of the movement 2* against the surface 3b* of the middle 3*. In this case, the clamp is held against the movement by a screw 4*.

[0007] However, such a solution can have problems. Indeed, there is a risk of plastic deformation of the clamp during assembly and / or under impact. This can lead to an undesirable loss of contact between the movement and the middle, or to an undesirable risk of removal of the clamp. SUMMARY

[0008] The object of the present invention is to provide a system for fixing a clock movement in a watch case which can overcome the above-mentioned drawbacks and improve the devices known in the prior art. In particular, the present invention proposes a fixing system whose reliability and robustness are improved with respect to the systems known in the prior art.

[0009] According to a first aspect of the present application, a system for securing a clock movement is defined by the following.

[0010] 1. A system for securing a movement of a clock to an element of a case, the system comprising:

[0011] - at least one clamp, in particular at least two clamps, preferably three clamps or four clamps, for first contacting the movement and second contacting the element of the case, and

[0012] - means for changing a stiffness of the at least one clamp, in particular a bending stiffness of the at least one clamp, when the movement is secured and / or displaced relative to the element of the case.

[0013] 2. The system according to definition 1, wherein the means for changing the stiffness of the at least one clamp are arranged such that a bending length of the at least one clamp is changed, in particular reduced, when the movement is secured to the element of the case or displaced relative to the element of the case from a rest position of a first surface of the movement against a second surface of the element of the case.

[0014] 3. The system according to definition 1 or 2, wherein a bearing force or contact of a first bent end of the at least one clamp against the movement and / or a bearing force or contact of a second bent end of the at least one clamp against the element of the case is changed when the movement is secured to the element of the case or displaced relative to the element of the case from a rest position of a first surface of the movement against a second surface of the element of the case.

[0015] 4. System according to any one of definitions 1 to 3, wherein, in the state where the movement is fixed to the element of the case and the movement is in the rest position with the first surface of the movement against the second surface of the element of the case, the means for varying the stiffness of at least one clamp comprise, between the clamp and the point at which the clamp can come into contact with the element of the case by flexing of the clamp, a first gap whose value is less than Lcl or less than Lcl / 3 or less than Lcl / 4 and / or whose value is greater than Lcl / 60 or greater than Lcl / 30, where Lcl is the length of projection in the plane of the movement of the third surface against which the clamp can bear and the length Lcl is between Lf / 10 and Lf, where Lf is the length of flexing of the clamp, and / or, in the state where the movement is fixed to the element of the case and the movement is in the rest position with the first surface of the movement against the second surface of the element of the case, the means for varying the stiffness of at least one clamp comprise, between the clamp and the point at which the clamp can come into contact with the element of the case by flexing of the clamp, a second gap whose value is less than Lc2 or less than Lc2 / 3 or less than Lc2 / 4 and / or whose value is greater than Lc2 / 60 or greater than Lc2 / 30, where Lc2 is the length of projection in the plane of the movement of the fifth surface against which the clamp can bear and the length Lc2 is between Lf / 10 and Lf, where Lf is measured in the rest state.

[0016] 5. System according to any one of definitions 1 to 4, wherein the means for varying the stiffness of at least one clamp comprise:

[0017] - a third surface forming a first non-zero angle with a fourth surface against which the clamp bears when the movement is in the rest position with the first surface of the movement against the second surface of the element of the case, and / or

[0018] - a fifth surface forming a second non-zero angle with a sixth surface against which the clamp bears when the movement is in the rest position with the first surface of the movement against the second surface of the element of the case.

[0019] 6. System according to definition 5, wherein the first angle is less than 45° or less than 20° or less than 15° or less than 10° and / or greater than 1 ° or greater than 2° and / or the second angle is less than 45° or less than 20° or less than 15° or less than 10° and / or greater than 1 ° or greater than 2°.

[0020] 7. System according to definition 5 or 6, wherein the first surface is flat and / or the second surface is flat and / or the third surface is flat and / or the fourth surface is flat and / or the fifth surface is flat and / or the sixth surface is flat.

[0021] 8. System according to definition 5 or 6, wherein the third surface is circular, in particular the third surface is a cylindrical portion, and / or the fifth surface is circular, in particular the fifth surface is a cylindrical portion.

[0022] 9. System according to any one of definitions 1 to 8, wherein the at least one clamp comprises a cross-section whose moment of inertia varies along the longitudinal axis, in particular by varying the width and / or the thickness, and / or such that the cross-section is constant or at least substantially constant over at least a portion of the length of the at least one clamp, in particular over at least half the length of the clamp.

[0023] 10. System according to any one of definitions 1 to 9, wherein the at least one clamp is made of a super-elastic alloy and / or a shape memory alloy, in particular a nickel-titanium alloy, for example Nitinol, or the at least one clamp is made of a nickel alloy.

[0024] 11. System according to any one of definitions 1 to 10, wherein the at least one clamp comprises an element, in particular a screw through-hole, for fixing to the movement or to an element of the case.

[0025] According to a first aspect of the invention, a clock unit is defined by the following definition.

[0026] 12. A clock unit, in particular a movement of a clock and / or an element of a case or a case, comprising a system according to any one of definitions 1 to 11.

[0027] 13. Clock unit according to definition 12, wherein the element of the case is a middle.

[0028] 14. Clock unit according to definition 12 or 13, wherein the third surface is formed on the movement and / or the fourth surface is formed on the element of the case.

[0029] 15. Clock unit according to definition 12 or 13, wherein the element of the case comprises a case bezel and / or the fourth surface is at least partially formed on the case bezel, or the movement comprises a case bezel and / or the third surface is at least partially formed on the case bezel.

[0030] According to a first aspect of the invention, a clock is defined by the following definition.

[0031] 16. A clock, in particular a watch, comprising a clock unit according to any one of definitions 12 to 15 and / or a system according to any one of definitions 1 to 11.

[0032] According to a second aspect of the invention, a system for fixing a movement of a clock is defined by the following definition.

[0033] 17. A system for fixing a movement of a timepiece to an element of a case, the system comprising at least one clamp, in particular at least two clamps, preferably three clamps or four clamps, for coming into contact firstly with the movement and secondly with the element of the case, the at least one clamp being made of a super-elastic alloy and / or a shape memory alloy, in particular a nickel-titanium alloy, for example Nitinol.

[0034] 18. The system according to claim 17, wherein the at least one clamp comprises a cross-section whose moment of inertia varies along a longitudinal axis, in particular by varying the width and / or the thickness, and / or such that the cross-section is constant or at least substantially constant for a maximum stress distribution throughout at least a portion of the length of the at least one clamp, in particular throughout at least half the length of the clamp.

[0035] 19. The system according to any one of claims 17 to 18, wherein the at least one clamp comprises an element, in particular a screw through-hole, for fixing to the movement or to the element of the case.

[0036] 20. The system according to any one of claims 17 to 19, wherein the thickness of the at least one clamp is greater than or equal to 0.5 mm.

[0037] 21. The system according to any one of claims 17 to 20, wherein the bending length of the at least one clamp is less than or equal to 1.35 mm.

[0038] According to a second aspect of the application, a timepiece unit is defined by the following.

[0039] 22. A timepiece unit, in particular a movement of a timepiece or an element of a case, comprising the system according to any one of claims 17 to 21.

[0040] According to a second aspect of the application, a timepiece is defined by the following.

[0041] 23. A timepiece, in particular a watch, comprising the timepiece unit according to claim 22 and / or the system according to any one of claims 17 to 21.

[0042] The features of the first aspect and the second aspect can be combined, unless logically or technically incompatible. BRIEF DESCRIPTION OF DRAWINGS

[0043] The drawings illustrate by way of example two embodiments of a timepiece according to the application.

[0044] Figure 1 and Figure 2 are cross-sectional views of assemblies known in the prior art.

[0045] Figure 3and Figure 4 is a view of a first embodiment of a clock in two states.

[0046] Figure 5 and Figure 6 is a view of a second embodiment of a clock in two states.

[0047] Figure 7 is a perspective view of details of the geometry of a first clamp usable in a securing system according to the invention.

[0048] Figure 8 is a summary table illustrating the characteristics of the clamps having the same geometry in several embodiments.

[0049] Figure 9 is a graph showing the characteristics of the securing system when the movement is displaced relative to the case Figure 8

[0050] Figure 10 is a perspective view of details of the geometry of a second clamp usable in a securing system according to the invention.

[0051] Figure 11 is a longitudinal sectional view of the geometry of a third clamp usable in a securing system according to the invention.

[0052] Figure 12 and Figure 13 is a view of details of an example of the geometry of the surface of the movement intended to engage the clamp.

[0053] Figure 14 is a view of a third embodiment of a clock in a rest position.

[0054] Figures 15 to 17 is a graph representing the restoring force of the movement, as a function of the displacement of the movement relative to the case, for different types of clamps. DETAILED DESCRIPTION

[0055] A first embodiment of a clock 400 is described below with reference to Figure 3 and Figure 4 The clock is, for example, a watch, in particular a wristwatch. The clock comprises a watch case or case 30 comprising a middle 3. The case 30 houses a movement 2 of the clock. The movement can be a mechanical movement or an electronic movement.

[0056] The movement 2 of the clock and / or the element 3 of the case and / or the case 30 can form or constitute part of a clock unit 200 comprising a system 10 for securing the movement 2 of the clock to the element 3 of the case 30 or helping this system 10. The element of the case can be, for example, a middle or an enlarged grommet.

[0057] ​The system 10 for fixing the movement 2 of a timepiece to an element 3 of the case comprises:

[0058] - at least one clamp 1, in particular at least two clamps, preferably three clamps or four clamps, for coming into contact firstly with the movement and secondly with the element of the case, and

[0059] - means 2a' for varying the rigidity of the at least one clamp, in particular the bending rigidity of the at least one clamp, when the movement is fixed to the element of the case and / or when the movement is displaced relative to the element of the case.

[0060] The system has the feature of using elastic case clamps, in particular whose rigidity can vary as a function of the load applied to them during displacement of the movement of the timepiece relative to the case, in the event of an impact or when the movement is assembled onto the case. According to another aspect, the system has the feature of implementing a case which is particularly rigid and very little affected by variations in manufacturing and / or assembly tolerances. Such an implementation has the advantage of providing a fixing system which is durable, which in particular prevents the risk of plastic deformation of the clamps which aid assembly and / or the risk of untimely removal of the fixing means of the clamps, in the event of an impact on the watch.

[0061] The rigidity of the clamps can be characterized by the strength of their bending after having been subjected to a load or a specified force. The rigidity of the clamps can be adjusted by varying their effective length when loaded and / or by varying the points or surfaces on which they bear. The means for varying the rigidity exploit this possibility.

[0062] The means for varying the rigidity of the at least one clamp are preferably arranged so as to vary the bending length of the at least one clamp, in particular to reduce the bending length of the at least one clamp, when the movement is fixed to the element of the case or when the movement is displaced relative to the element of the case from a rest position of the first surface 2b of the movement against the second surface 3b of the element of the case. The first surface 2b is for example one face of the movement. The second surface 3b is for example a support surface formed in the case, for example in the middle.

[0063] In the state in which the movement is assembled in the case, the at least one clamp 1 is pressed against a surface 2A of the movement. The at least one clamp rests against a surface 3A of the case, in particular against an end of the surface 3A of the case. For example, the surface 3A is a support region of a cutout 31 or recess 31 formed in an element of the case, in particular in the middle. Thus, the clamp 1 is elastically deformed when the movement is assembled, such that the elastic restoring force of the clamp holds the surface 2b of the movement 2 against the surface 3b of the case 3. In this case, the clamp is held on the movement by means of a screw 4. For example, the screw 4 is screwed into an internal thread provided in the movement. The screw passes through a hole 14 formed in the clamp 1. The head of the screw rests against a surface of the clamp 1. For example, the first surface 2b and the second surface 3b are flat. They are preferably perpendicular to an axis Al of the movement. This axis Al is perpendicular to a plane of the movement, in particular to a frame plane of the movement, and / or this axis Al is parallel to the direction along which the movement is inserted into the element 3 of the case.

[0064] The flexing effective length Lf of the clamp corresponds to a limited portion of the total length L of the clamp. The flexing effective length Lf extends between a first region forming the first curved end 12 and a second region forming the second curved end 13. The first end 12 is located at the contact boundary between the movement and the clamp. The second end 13 is located at the contact boundary between the case and the clamp. The length La is the length over which the clamp rests against the movement. This length can be discontinuous. It extends between the end boundaries at which the clamp 1 rests against the movement.

[0065] In the first embodiment, the support surface 2A of the movement comprises at least one surface portion 2a' which forms an angle a with the frame of the movement. This portion 2a' is adjacent to the portion 2a on which the screw 4 presses the clamp against the frame of the movement. For example, the portion 2a is flat. Thus, when the movement is in the rest position in which the first surface 2b of the movement rests against the second surface 3b of the element of the case, the surface portion 2a' forms a non-zero angle a with the portion 2a against which the clamp rests.

[0066] When the movement 2 is assembled in the case 30, the clamp 1 is elastically deformed by coming into contact, wholly or partially, with the surface 3A under the action of the screw 4. The clamp is elastically deformed over an axial interference distance which corresponds to the physical interference between the clamp and the case before the elastic deformation of the clamp. Once the movement has been assembled, the clamp is pressed against the surface 2A and held in a pre-tensioned state by means of the screw 4. In various configurations, the flexing length Lf of the clamp is defined in particular by the geometry of the surface 2A. In the particular configuration shown, the flexing length Lf is equal to the length La divided by 1.5. This gives the clamp a first stiffness which the clamp maintains in particular during impacts of a strength greater than a specified threshold until the clamp comes into contact again with the portion 2a'. When this threshold is reached, the clamp is elastically deformed and the first surface 2b of the movement is pressed against the second surface 3b of the element of the case. Figure 3 Within the particular configuration shown, Lf is approximately La / 1.5, which confers a first stiffness on the clamp, which the clamp maintains in particular during impacts of a strength greater than a specified threshold until the clamp comes into contact again with the portion 2a'. When this threshold is reached, the clamp is elastically deformed and the first surface 2b of the movement is pressed against the second surface 3b of the element of the case. Figure 4As shown, the movement is axially displaced by a distance d relative to the case. As a result, the clamp is in contact with the portion 2a'. This contact changes the support point of the clamp, which in particular can increase the restoring force of the clamp, while the amount of the minimum axial displacement of the movement generated by the increased restoring force prevents its plastic deformation. The geometry of the portion 2a' thus at least gives the clamp a second stiffness, which the clamp can maintain until the elastic restoring force of the clamp is released, i.e. until the clamp is in contact with the portion 2a'. Moreover, the portion 2a' can distribute the stress over a larger surface of the clamp, thus avoiding excessive stress concentrations that can exceed the elastic limit of the material from which the clamp is made.

[0067] When the configuration of the movement changes from Figure 3 to the configuration of Figure 4 , the bending length Lf of the clamp can change and it can in particular be between La / 4 ( Figure 4 ) and La / 1.5 ( Figure 3 ). In particular, the length Lf can quickly change from La / 1.5 to La / 4 between the configuration of Figure 3 and the configuration of Figure 4 . The mode of loading the clamp can also be quickly changed by changing from a configuration similar to an embedded beam to a configuration similar to a four-point bending beam.

[0068] The angle a is preferably strictly less than 45° or less than 20° or less than 15° or less than 10°. The angle a is preferably greater than 1°, in particular greater than 2°. The portion 2a' should thus be different from a simple bevel produced by manufacturing the surface 2A. Moreover, the portion 2a' can occupy all or part of the surface 2A.

[0069] Of course, the clamp can be pressed against the portion 2a' at the time of assembly, i.e. when the movement is assembled or fixed inside the case, that is to say when the distance d between the movement and the element of the case is zero. The advantage of such a configuration is to increase the restoring force generated by the clamp when the movement is assembled, without generating stresses that can cause residual deformation of the clamp.

[0070] Thus, when the movement is fixed to an element of the case or when the movement is displaced relative to an element of the case from a rest position in which the first surface 2b of the movement abuts against the second surface 3b of the element of the case, the support or contact of the first bent end 12 of the clamp against the movement is changed.

[0071] In this first embodiment, the means for changing the stiffness of at least one clamp comprise a portion 2a'. For example, the portion 2a' is flat.

[0072] Reference will now be made to Figure 5 and Figure 6A second embodiment of the clock 400 is described. According to the second embodiment, the clock differs from the clock of the first embodiment only in the means for changing the stiffness of at least one clamp.

[0073] In the second embodiment, the supporting surface 3A of the watch case includes at least one surface portion 3a' which forms an angle β with the frame of the movement or with a plane perpendicular to the axis A1 of the movement. In the resting position of the movement or when the movement is secured in the watch case, this portion 3a' is adjacent to a clamp-supported portion 3a. For example, portion 3a is flat and, for example, perpendicular to the axis A1 of the movement. Therefore, portion 3a' of surface 3A forms an angle β with portion 3a of surface 3A.

[0074] When the movement 2 is assembled within the watch case 30, the clamp 1 elastically deforms under the action of the screw 4 through full or partial contact with the surface 3A. The clamp elastically deforms at an axial interference distance corresponding to the object interference between the clamp and the watch case before the elastic deformation. Once the movement has been installed, the clamp rests against the surface 2A and is held in a pre-tensioned state by the screw 4. In various configurations, the bending length Lf of the clamp is specifically defined by the geometry of the surface 3A. Figure 5 Within the specific structure shown, Lf is approximately La / 2.5, which imparts a first stiffness to the clamp, which maintains this first stiffness, particularly during impacts exceeding a specified threshold, until the clamp re-engages with portion 3a'. When this threshold is reached, as... Figure 6 As shown, the movement is axially displaced by a distance d relative to the watch case. As a result, the clamp comes into contact with part 3a'. This contact changes the support point of the clamp, which in particular increases the restoring force of the clamp, and at the same time, prevents plastic deformation of the movement by minimizing the amount of axial displacement of the movement, especially through the increased restoring force. Therefore, the geometry of part 3a' gives the clamp at least a second stiffness, which the clamp can maintain until the elastic restoring force of the clamp is released, i.e., until the clamp comes into contact with part 3a'.

[0075] When from Figure 5 The structure becomes Figure 6 During the construction of the fixture, the bending length Lf can be varied, and in particular it can be within La / 4 ( Figure 6 ) and La / 2.5 ( Figure 5 Between ) . In particular, in this case, the length Lf can be between ) . Figure 5 The structure and Figure 6 The structure changes from La / 2.5 to La / 4.

[0076] The angle β is preferably strictly less than 45° or less than 20° or less than 15° or less than 10°. This angle β is preferably greater than 1 °, in particular greater than 2°. Thus, the portion 3a' should be different from a simple bevel created by the manufacturing surface 3A. Moreover, the portion 3a' can occupy all or part of the surface 3A.

[0077] Of course, the clamp can be pressed against the portion 3a' when the movement is assembled in the case, that is to say when the distance d between the movement and the element of the case is zero. The advantage of such a construction is to increase the restoring force created by the clamp when the movement is assembled, without creating stresses that can lead to residual deformation of the clamp.

[0078] Thus, when the movement is fixed to the element of the case or the element of the case is displaced from the rest position of the first surface 2b of the movement against the second surface 3b of the element of the case, the bearing force or contact of the second curved end 13 of the clamp against the element of the case is changed.

[0079] In this second embodiment, the means for changing the stiffness of at least one clamp comprise a portion 3a'. For example, the portion 3a' is flat.

[0080] A third embodiment of the clock 400 is described below. This embodiment is shown in Figure 14 It combines the first embodiment and the second embodiment. Thus, in this third embodiment, the means for changing the stiffness of at least one clamp comprise: a sloping portion on the movement for engaging at least one clamp, in particular the portion 2a' of the first embodiment as shown in Figure 3 and Figure 4 a sloping portion on the element of the case for engaging at least one clamp, in particular the portion 3a' of the second embodiment as shown in Figure 5 and Figure 6 .

[0081] Thus, when the movement is fixed to the element of the case or the element of the case is displaced from the rest position of the first surface 2b of the movement against the second surface 3b of the element of the case, the bearing force or contact of the first curved end 12 of the clamp against the movement and the bearing force or contact of the second curved end 13 of the clamp against the element of the case are changed.

[0082] In the various embodiments, it is advantageous to provide means for changing the stiffness of the clamp at each clamp. Preferably, in the same clock, the means for changing the stiffness of the clamp are identical for each clamp.

[0083] Each clamp can have a parallelepiped shape or Figure 7 a substantially parallelepiped shape as shown in

[0084] For example, one of the clamps can be a bar. Several or all of the clamps can be bars.

[0085] For example, one of the clamps can have a length L in its longitudinal direction that is at least 1.2 times or at least 1.5 times or at least 1.8 times or at least 2 times greater than a larger transverse dimension (width) L' measured in a transverse direction perpendicular to the longitudinal direction. The length and width are illustrated in Figure 7 , Figure 10 and Figure 11 . Several or all of the clamps can have such a shape.

[0086] Advantageously, the or each clamp comprises a section S whose moment of inertia varies along the longitudinal axis 11 of the clamp.

[0087] In a first alternative illustrated in Figure 10 , the width L' of the clamp varies along the longitudinal axis 11. This variation is present between the fixing element 14 and the end 15 of the clamp, in particular over more than half the portion extending between the fixing element 14 and the end 15 of the clamp. The width L' preferably decreases as the end 15 is approached.

[0088] In a second alternative illustrated in Figure 11 , the thickness e of the clamp varies along the longitudinal axis 11. This variation is present between the fixing element 14 and the end 15 of the clamp, in particular over more than half the portion extending between the fixing element 14 and the end 15 of the clamp. The thickness e preferably decreases as the end 15 is approached.

[0089] The variation in the width and / or thickness and / or geometry of the clamp can be such that the section varies so that the maximum stress distribution in this section is constant or substantially constant at least over a portion of the length of the clamp, in particular between the fixing element 14 and the end 15 of the clamp, in particular over more than half the portion extending between the fixing element 14 and the end 15 of the clamp. In other words, the clamp can in particular have a profile of the same bending resistance or "equal stress". More generally, the section of the clamp can vary so that the stress therein is optimally distributed, thereby minimizing the stress.

[0090] In all the embodiments described above, the portion 2a' has been described as being formed on the movement and the portion 3a' has been described as being formed on an element of the case.

[0091] In all the embodiments described above, the movement is arranged to be assembled directly inside the middle. However, alternatively, the movement can be assembled on another element of the case, in particular on a bottom cover or bezel arranged to be added to the middle.

[0092] Of course, the clock unit 200 can also comprise a housing collar or an enlarged collar, which can be rigidly connected to the movement or to the middle by means of the fixing means connected. In such a case, the portion 2a' can be formed at least partially on the housing collar, or the portion 3a' can be formed at least partially on the housing collar.

[0093] In all the embodiments described above, the housing clamp has been described as being fixed on the movement. Alternatively, the fixing means for the clamp can be mounted on the housing collar. Additionally alternatively, the fixing means for the clamp can be mounted on an element of the case, in particular on the middle.

[0094] In all the embodiments described above, the portions 2a' and 3a' have been described as flat portions.

[0095] However, alternatively, as illustrated in Figure 12 regarding the portion 2a', the portion 2a' and / or the portion 3a' can be convex or rounded, in particular can have the shape of a cylindrical portion.

[0096] Additionally alternatively, as illustrated in Figure 13 regarding the portion 2a', the portion 2a' and / or the portion 3a' can be discontinuous, in particular formed by steps.

[0097] More generally and preferably, in the state where the movement is fixed to an element of the case, the movement being in a rest position of its first surface 2b against a second surface 3b of the element of the case, there can be a gap e1 between the clamp and the point at which the clamp comes into contact with the movement by flexing of the clamp ( Figure 3 ). The value of the gap e1 is less than Lc1 or less than Lc1 / 3 or less than Lc1 / 4, and / or the value of the gap e1 is greater than Lc1 / 60 or greater than Lc1 / 30, where Lc1 is the length of the projection of the portion 2a' in the plane of the movement frame. Furthermore, the length Lc1 is between Lf / 10 and Lf, where Lf is measured in the rest state.

[0098] More generally and preferably, in the state where the movement is fixed to an element of the case, the movement being in a rest position of its first surface 2b against a second surface 3b of the element of the case, there can be a gap e2 between the clamp and the point at which the clamp comes into contact with the element of the case by flexing of the clamp ( Figure 14 ). The value of the gap e2 is less than Lc2 or less than Lc2 / 3 or less than Lc2 / 4, and / or the value of the gap e2 is greater than Lc2 / 60 or greater than Lc2 / 30, where Lc2 is the length of the projection of the portion 3a' in the plane of the element of the case. Furthermore, the length Lc2 is between Lf / 10 and Lf, where Lf is measured in the rest state.

[0099] In alternative to any clamp, each clamp has an element 14 for fixing to an element of the movement or to the case. For example, this element is a through hole 14 for the passage of a screw 4.

[0100] In alternative to any clamp, the clamp can be made of steel or superelastic alloy and / or shape memory alloy, in particular nickel-titanium alloy, for example Nitinol or nickel alloy.

[0101] In alternative to any clamp, the clamp 1 can or can not be flat. Thus, the clamp can have a curved geometry. The clamp 1 can have a profile that is selectively symmetrical.

[0102] Figure 8 A summary table is shown reporting the characteristics of the clamps having the same geometry constant in section (L = 3.3 mm, L' = 2.05 mm, Lf = 1.0 mm and e = 0.35 mm) and made of the same material (Durnico steel) for different assembly configurations A, B, C, D.

[0103] Configuration A corresponds to the case configuration of the first embodiment shown in Figure 1 and Figure 2 of the prior art.

[0104] Configuration B corresponds to the case configuration of the first embodiment shown in Figure 3 and Figure 4 of the first embodiment.

[0105] Configuration C corresponds to the case configuration of the second embodiment shown in Figure 5 and Figure 6 of the second embodiment.

[0106] Configuration D corresponds to the case configuration of the third embodiment shown in Figure 14 of the third embodiment.

[0107] It should be noted that, for a same interference I of the case with the clamp defining a specified elastic deformation of the clamp, the elastic recovery force F generated by the clamp after the component has been subjected to a specified intensity of impact varies substantially according to the configuration. This leads to a significant variation of the axial displacement d of the movement with respect to its respective case and, consequently, to a residual deformation Def of the clamp that can or can not occur more or less according to the configuration.

[0108] Figure 8The table highlights in particular the fact that the constructions B, C, D make it possible to provide a particularly rigid assembly while minimizing the residual deformation of the clamps, whereas the clamp of construction A is heavily plastically deformed, in particular because of the excessive axial displacement amount d generated during the impact. In view of this, in this construction Def > I, the plastic deformation of the clamp in this case leads to the loosening of the movement away from the middle, i.e. to the loss of contact between the movement and the middle. Thus, after the impact, the movement is no longer assembled in a satisfactory manner in this case. Advantageously, construction D makes it possible to limit the displacement of the movement relative to the case and the residual deformation of the clamp to the greatest extent possible.

[0109] Figure 9 The rigidity characteristics of the clamp in each of the constructions A, B, C, D are shown as a function of the axial displacement amount or deformation amount d' of the clamp, with d' = d + I. Unlike the curve representing the rigidity characteristics of the clamp contributing to construction A, the curves representing the rigidity characteristics of the clamps contributing to constructions B, C and D respectively have an inflection point. This generates a first clamp rigidity in particular when the movement is assembled (d' < I + do), and a second clamp rigidity in particular when the distance d of the loosening of the movement from the case is greater than do during an impact of predetermined intensity (leading to a clamp axial deformation amount d' > I + do), where the distance do is specific to the geometry of this embodiment and can correspond to a movement displacement amount leading to the recontact of the clamp with the elements of the movement or of the case. For example, more generally, the clamp can have a first rigidity and a second rigidity when the movement is assembled within the elements of the case, or a second rigidity for example once the movement has been assembled after an impact of predetermined intensity.

[0110] Thus, Figure 9 The rigidity adjustment of the clamps of constructions B, C and D when tensioned is highlighted, due to the change in their effective length or their support points or surfaces, regardless of whether this is during the assembly of the movement or after the assembly of the movement, during an impact of the case.

[0111] As mentioned above, the clamp can be made of steel, in particular Durnico steel. For its superelasticity characteristics, a shape memory alloy can advantageously be chosen, for example Nitinol. Since the phase change of the material based on its deformation rate depends on the load it is subjected to during assembly or the load it can be subjected to during an impact, a clamp formed from such an alloy indeed has the advantage of generating significantly less force variation when the specified prestress threshold is exceeded compared to a clamp made of Durnico steel. This property is therefore particularly advantageous for overcoming, as far as possible, the force variation induced by the variation of the assembly configuration resulting from the manufacturing and / or assembly tolerances of the movement and of the case, thus making it possible to provide a particularly robust assembly device.

[0112] Moreover, compared to the housing clamp devices known in the prior art, the clamps formed from such superelastic alloys can generate very great elastic return forces. Thus, in order to increase the rigidity of the housing, it is particularly advantageous to select such a material, the advantages of which are emphasized by the Applicant's research and disclosed in patent application EP 2 458 456, namely a particularly significant reduction in the acceleration to which the movement is subjected, for example during an impact on a hard surface.

[0113] The application also relates to a method for operating a securing system that is the object of the application, in particular for operating the embodiments described above. According to this operating method and / or in the various embodiments described above, the operation of the securing system comprises a step of varying the rigidity of at least one clamp, in particular the bending rigidity of at least one clamp, when the movement is secured and / or when the movement is displaced relative to the element of the case.

[0114] In particular, the bending length of at least one clamp, in particular the bending length of at least one clamp, is varied, in particular reduced, when the movement is secured and / or when the movement is displaced relative to the element of the case from a rest position in which the first surface 2b of the movement bears against the second surface 3b of the element of the case.

[0115] Thus, according to a second aspect of the application, the timepiece 400, in particular a watch or a unit 200, comprises a system 10 for securing the movement 2 of the timepiece to an element 3 of the case 30, the system comprising at least one clamp 1, in particular at least two clamps, preferably three clamps or four clamps, which first come into contact with the movement and secondly with the element of the case, said at least one clamp being made of a superelastic and / or shape memory alloy, in particular a nickel-titanium alloy, for example nitinol.

[0116] Nitinol is a superelastic and shape memory alloy. Indeed, within the temperature range corresponding to the use of the clamp (for example, between -10°C and 40°C), nitinol is in the austenitic phase and is therefore superelastic.

[0117] Nitinol is an alloy of nickel and titanium, in which the two elements are present in approximately the same percentage, i.e. approximately 55% or 60% by weight of nickel and approximately 45% or 40% by weight of titanium, and possibly in a smaller proportion of alloying elements such as chromium, cobalt or niobium. Other shape memory alloys exist, such as AuCd, CuAlBe, CuAINi or CuZnAl in single-crystal or polycrystalline form.

[0118] Furthermore, the alloy can be subjected to a specific heat treatment in order to obtain its superelastic properties.

[0119] For example, the alloy 60NiTi nominally consists of 60% by weight of nickel and 40% by weight of titanium. The alloy 55NiTi nominally consists of 55% by weight of nickel and 45% by weight of titanium. The alloy Nitinol #1 consists of 54.5% to 57.0% by weight of nickel and 43.0% to 45.5% by weight of titanium, and has at most 0.25% by weight of other elements, in particular, for example, chromium, cobalt, copper, iron or niobium.

[0120] The results shown in Figures 15 to 17 The Nitinol alloys forming the basis of the study shown in

[0121] For example, the alloy CuAl12Be (0.45-0.68) nominally consists of 12% by weight of aluminum and 0.45% to 0.68% by weight of beryllium, the rest consisting of copper.

[0122] For example, the alloy CuAl13Ni4 nominally consists of 83% by weight of copper, 13% by weight of aluminum and 4% by weight of nickel.

[0123] All the materials described above are suitable for manufacturing the clamps.

[0124] For example, Figure 15 A graph showing the variation of the restoring force as a function of the "interference I" of the two clamps made of Durnico steel (curve 6) and Nitinol (curves 5a, 5b) respectively, in their elastic range, as a function of the pre-tensioning state thereof, after having been assembled according to the configuration A, is shown in Figure 10 The "isostress" geometry in this case is similar to that shown in

[0125] This graph shows that the curves 5a, 5b, unlike the curve 6 which has only a single finite portion, comprise two separate portions 5a, 5b having significantly different slopes. In the assembled configuration, the Nitinol clamps are pre-stressed so as to act according to the characteristics of the portion 5b of the curve. The amount of force variation that can be generated by the Nitinol clamps is thus minimized with respect to the amount of force variation that can be generated by the Durnico steel clamps, for a given variation of the interference.

[0126] To reinforce the case as best as possible and to incorporate the super-elastic properties of the alloy in the mounting phase, the geometry of the Nitinol clamp can be changed with respect to the clamps known in the prior art. For example, the thickness e of the Nitinol clamp can be increased and / or the flex length Lf is minimized, optionally constant as a function of the load, compared to the clamp made of Durnico steel.

[0127] Preferably, for the Nitinol clamp, e > 0.5 mm.

[0128] Preferably, for the Nitinol clamp, Lf < 1.35 mm.

[0129] For example, Figure 16 A graph representing the variation of the elastic return force of the two clamps as a function of their pre-tensioning state, in their elastic range, as a function of their "interference I" after they have been mounted in a movement according to the architecture A, respectively made of Durnico steel (curve 6) and Nitinol (curves 5a, 5b) is shown. Their "iso-stress" geometry is similar in this case to that shown in Figure 10 where Lf = 1.35 mm and the width L' has the greater dimension 2.05 mm. However, the thickness is different, e = 0.37 mm in the Durnico steel clamp and e = 1.75 mm in the Nitinol clamp.

[0130] In this case, a significant increase in the elastic return force is observed compared to that produced by the Durnico steel clamp, and there is no risk of residual deformation of the Nitinol clamp.

[0131] To limit the increase in the thickness of the clamp, it is possible to reduce the length Lf of the clamp. For example, Figure 17 A graph representing the variation of the elastic return force of the two clamps as a function of their pre-tensioning state, in their elastic range, as a function of their "interference I" after they have been mounted in a movement according to the architecture A, respectively made of Durnico steel (curve 6) and Nitinol (curves 5a, 5b) is shown. Their "iso-stress" geometry is similar in this case to that shown in Figure 10 where the width L' has the greater dimension 2.05 mm. However, the thickness is different, e = 0.37 mm in the Durnico steel clamp and e = 0.5 mm in the Nitinol clamp. The length Lf is also different, Lf = 1.35 mm in the Durnico steel clamp and Lf = 0.72 mm in the Nitinol clamp.

[0132] A significant increase in elastic return force is observed compared to the elastic return force generated by a Durnico steel clamp, and there is no risk of residual deformation of the Nitinol clamp. Furthermore, for a given variation in interference, the variation in force generated by the Nitinol clamp is minimized compared to the variation in force that can be generated by a Durnico steel clamp. Thus, according to the second aspect of the application, the system has the feature of implementing a case that is particularly rigid and extremely little affected by variations in manufacturing and / or assembly tolerances.

[0133] In the embodiments shown in the prior art and in Figure 1 and Figure 2 , the flexure active length Lf* of the clamp corresponds to a limited portion of the total length L* of the clamp. The length Lf* is in particular significantly less than the bearing length La* of the clamp against the movement, in particular Lf* is approximately La* / 4. It can be demonstrated that this length Lf* is insufficient when the movement is assembled in the case, and this presents the risk of causing a residual deformation of the clamp, which reduces the elastic return force that can be generated by said clamp. This situation in particular can lead to a loss of contact between the surfaces 2b* and 3b* associated respectively with the movement 2* and the case 3*. This situation also reduces the action generated by the head of the screw 4*, and this can lead to the risk of unscrewing of the screw 4* at an inopportune moment.

[0134] Conversely, if the length Lf* is increased on the basis of these considerations, it can be demonstrated that this length Lf* is excessive after the movement has been assembled in the case, in particular for a predetermined threshold of shock resistance and / or a given range of displacement of the movement, and this also presents the risk of causing a residual deformation of the clamp, which can reduce the elastic return force initially generated by said clamp.

[0135] Thus, with the materials known in the prior art that can be chosen for the manufacture of the clamp, the space available at the interface of the movement with the case is not sufficient to completely prevent the risk of residual plastic deformation of said clamp caused by a shock of a given threshold.

[0136] Thanks to the solutions described herein, these problems can be solved, and the securing system can be more rigid and / or more reliable thanks to the material used for the clamp and / or the geometry on which the clamp is based. Indeed, in particular according to the solutions described herein, in particular during the mounting and / or during the shock, the stiffness of the elastic case clamp can vary as a function of the load applied to it, in particular as a function of the displacement of the movement of the watch relative to the case.

[0137] In the present text, "super-elastic alloy" preferably means an alloy having a deformation of more than 2% or more than 5% or more than 8% at the elastic limit.

[0138] In the present text, the weight percentage of an element is expressed as "weight %".

Claims

1. A system (10) for securing a clock movement (2) to an element (3) of a watch case (30), the system comprising at least one clamp (1) for first contacting the movement and secondly contacting an element of the watch case, the at least one clamp being made of a superelastic alloy and / or shape memory alloy having a parallelepiped shape, and the element of the watch case being a central or enlarged bushing. The system further includes means for changing the bending stiffness of at least one clamp when components of the movement relative to the case are fixed and / or displaced, the means for changing the bending stiffness of at least one clamp being configured such that the bending length of at least one clamp is changed when components of the movement relative to the case are fixed and / or displaced.

2. The system according to claim 1, wherein, At least one fixture includes a cross section whose moment of inertia varies along a longitudinal axis (11), and / or such that the cross section causes the maximum stress distribution to be constant or at least substantially constant throughout at least a portion of the length of at least one fixture.

3. The system according to claim 1 or 2, wherein, At least one clamp includes an element (14) for securing to the movement or to the watch case.

4. The system according to claim 1 or 2, wherein, At least one fixture has a thickness (e) greater than or equal to 0.5 mm.

5. The system according to claim 1 or 2, wherein, The bending length (Lf) of at least one clamp is less than or equal to 1.35 mm.

6. The system according to claim 1, wherein, The system includes at least two clamps made of nickel-titanium alloy.

7. The system according to claim 6, wherein, The system includes three or four clamps, which are made of nitinol.

8. The system according to claim 2, wherein, The moment of inertia of the cross section varies by changing its width and / or thickness, and / or the cross section such that the maximum stress distribution is constant or at least substantially constant throughout at least half the length of the fixture.

9. The system according to claim 3, wherein, The element (14) is a through hole for the screw (4).

10. A clock unit (200) comprising the system according to any one of claims 1 to 9.

11. The clock unit (200) according to claim 10, wherein, The clock unit is a component of the clock's movement or case.

12. A clock (400) comprising a clock unit according to claim 10 or 11 and / or a system according to any one of claims 1 to 9.

13. The clock (400) according to claim 12, wherein, The clock mentioned is a wristwatch.

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