Friction system for a timepiece movement

Abstract

To transmit high torque, to facilitate manufacture, and to provide easily manageable reproducibility of applied friction torque.SOLUTION: An arbor 1 having a longitudinal axis L, a first fixing element 2 having a first bearing surface mounted to rotate integrally with the arbor, and a second fixing element 7, a toothed part 3 being mounted to rotate freely on the arbor between the first fixing element and the second fixing element, the toothed piece is integral with a socket joint 4 having a second bearing surface 42, and the second fixing element comprises a body 72 and an elastic bracket 71 projecting from the body and extending towards the toothed piece, the elastic bracket being designed to be elastically pressed against the second bearing surface and to deform elastically under strain to form a kinematic linkage both between the first fixing element and the toothed piece, and between the second fixing element and the socket joint integral with the toothed piece, up to a predetermined friction torque.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to the field of mechanical watches.

[0002] The invention relates more particularly to friction systems for timepiece movements, for example for setting the time. [Background technology]

[0003] Friction systems are commonly used in watch movements. They allow a first part to be rotationally integrated with a second part until a torque limit is reached. Beyond this limit, the two parts are no longer rotationally integrated. This type of system is commonly used for hour and minute displays, especially in cannon pinions that drive the display hands or display discs.

[0004] Cannon pinions are usually indented to ensure friction between the cannon pinion and the pivot shank. Indenting consists of crimping the tube contained in the cannon pinion on the side opposite the shoulder or pivot shank clearance. Crimping is a manual process, and the result is unpredictable, depending on the dexterity and skill of the watchmaker.

[0005] Accurate adjustment of the friction torque is therefore difficult, and therefore precise control of the applied clamping force is important, and conventional manual indentation processes do not provide this precision or the required repeatability.

[0006] Another drawback is that the friction caused by the indentation cannot withstand the transmission of high torques and is sensitive to assembly and disassembly.

[0007] Other solutions for achieving friction include the use of metal foils as described in US Pat. No. 5,629,399, but it is difficult to guarantee production reproducibility from batch to batch.

[0008] Patent document 2 describes another solution for generating friction, which consists in using a helical friction spring with an inner part pressing against a first annular support surface that is rotationally integral with the first toothed part and an outer part pressing against a second annular support surface that is integral with the second toothed part, the inner and outer parts being connected by at least one helical elastic arm. However, these solutions are complex to use and their considerable footprint precludes specific implementation in watch movements. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] French Patent No. 2394839 [Patent Document 2] Swiss Patent No. 712197 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention aims to remedy at least one of the above-mentioned drawbacks.

[0011] It is also an object of the present invention to provide a friction system that allows for the transmission of high torque, is easy to manufacture, and provides easily manageable repeatability of the applied friction torque.

[0012] The present invention also makes it possible to provide a friction system with a limited footprint, where the radial footprint of the system is determined by the footprint of the toothed component, rather than the footprint of the friction system. [Means for solving the problem]

[0013] To this end, the invention relates to a friction system for a clock movement, comprising an arbor having a longitudinal axis L and designed to be attached to the clock movement, a first fixing element mounted to rotate integrally with the arbor, the first fixing element having a first support surface, a second fixing element mounted to rotate integrally with the arbor, and a toothed part mounted to rotate freely on the arbor between the first and second fixing elements.

[0014] According to the invention, the toothed part is integral with a socket joint having a second support surface, and the second fixing element comprises a body configured to rotate integrally with the arbor and a resilient bracket protruding relative to the body and extending towards the toothed part, said resilient bracket being pressed resiliently against said second support surface of the socket joint, said resilient bracket being designed to elastically deform under strain from the second support surface and to form a kinematic linkage both between the first fixing element and the toothed part and between the second fixing element and the socket joint integral with the toothed part up to a predetermined friction torque.

[0015] The construction of the friction system according to the invention allows the entire length of the arbor to be used while limiting the overall footprint of such a system in the radial direction, making such a friction system more suitable for timepiece movements, especially those with many complications.

[0016] According to the invention, the friction torque can be fully adjusted by axially controlling the pressing-in of the second fixing element on the arbor, and the strain on the socket joint due to the elastic strain of the elastic bracket makes it possible to achieve a more gradual increase in friction torque, which facilitates the accurate and repeatable setting of a predetermined friction torque.

[0017] Additionally, such friction systems according to the present invention are not subject to continuous and repeated assembly / disassembly.

[0018] In addition to the characteristics mentioned in the previous paragraph, the friction system according to the invention may have one or more of the following complementary characteristics, individually or in any technically possible combination: The resilient bracket extends along an axis substantially parallel to the longitudinal axis of the arbor. The second support surface is a conical support surface. The second bearing surface is an inner bearing surface formed at the level of the reamed hole in the socket joint and inclined towards the longitudinal axis of the arbor. The second support surface is a conical outer support surface formed around the socket joint and sloping outward from the socket joint. The resilient brackets are resiliently pressed at their free ends against said second support surface of the socket joint. The free end of the elastic bracket has a rounded or beveled shape. The first support surface of the first fixation element is flat or conical. · Socket joints are made integral with toothed parts. · Socket joints are separate parts attached to toothed parts. The socket joint is pressed into the tubular section of the toothed part.

[0019] The invention also relates to a timepiece movement comprising a friction system according to the invention.

[0020] The present invention also provides a method for assembling a friction system according to the present invention, comprising the steps of: providing an arbor; - forcing the first fixation element onto the shaft into a predetermined axial position; - sliding the first toothed part on the shaft to the first fixing element so that the first toothed part comes into contact with the first fixing element, the first toothed part being integral with the socket joint; gradually pressing the second fixing element with the elastic bracket directed towards the socket joint onto the arbor, compressing the elastic bracket against the socket joint and obtaining a frictional kinematic linkage both between the first fixing element and the first toothed part and between the second fixing element and the socket joint integral with the toothed part until a predetermined friction torque is obtained; The present invention relates to a method comprising: Other characteristics and advantages of the invention will become apparent from the following detailed description, given by way of non-limiting example with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0021] [Figure 1] 1 shows a perspective view of a first exemplary embodiment of a friction system according to the present invention; [Figure 2] 2 shows an exploded view of the friction system shown in FIG. 1. [Figure 3] 2 shows a longitudinal section along axis AA of the first exemplary embodiment of the friction system shown in FIG. 1; [Figure 4] FIG. 2 is a detailed view particularly showing the friction-generating contact area of ​​the friction system shown in FIG. 1. [Figure 5] 10 is a detailed view showing the friction-generating contact area of ​​an alternative embodiment of the friction system according to the present invention. FIG. [Figure 6] 1 shows an exploded view of a second exemplary embodiment of a friction system according to the present invention. [Figure 7] 7 shows a longitudinal section along axis AA of the second exemplary embodiment of the friction system shown in FIG. 6. [Figure 8] 2 shows a longitudinal section along axis AA of a third exemplary embodiment of a friction system according to the invention; [Figure 9] 1 is a schematic diagram of a timepiece comprising a timepiece movement fitted with a friction system according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0022] 1, a first exemplary embodiment of a friction system 100 according to the present invention is shown. The system comprises an arbor 1 designed to be attached to a watch movement 200, the arbor 1 extending along a central longitudinal axis L that forms the axis of rotation of the arbor 1. The arbor 1 can comprise sections of different diameters and / or different shapes.

[0023] The arbor 1 comprises a first toothed part 3, for example a wheel, mounted so as to rotate freely on the arbor 1. Alternatively, this first toothed part 3 can be a pinion or another element designed to be frictionally mounted on the arbor 1.

[0024] The arbor 1 can also hold several toothed components that are integral with the arbor 1 and can have a number of known shapes according to the needs of those skilled in the art.

[0025] The arbor 1 is, for example, a cannon pinion.

[0026] As shown in Figure 1, the arbor 1 comprises a second, fixed toothed part 5 which is integral with the arbor 1. This second, fixed toothed part 5 may be a pinion as shown or a wheel. In the example shown, the second toothed part 5 is made integral with the arbor 1. According to an alternative embodiment, this second toothed part 5 can be pressed onto the arbor 1 so as to be integral with the movement of the arbor 1.

[0027] As shown in FIG. 2 , which shows an exploded view of a first exemplary embodiment of a friction system 100 according to the present invention, the friction system 100 comprises a first fixing element 2 forming a first support element, such as an annular flange 2, which is pressed onto the arbor 1 so as to be integral with the movement of the arbor 1.

[0028] This annular flange 2 has a first annular support surface 20 which serves as a first friction surface between the annular flange 2 and the first toothed part 3. The first toothed part 3 rests on this annular support surface 20 via its bottom surface.

[0029] The friction system 100 also comprises a second fixing element 7 which is pressed onto the arbor 1. The first toothed part 3 is mounted between the first fixing element 2 and the second fixing element 7. The axial position of the second fixing element 7 along its longitudinal axis L forms a friction kinematic linkage and makes it possible to adjust the friction force of the friction system 100.

[0030] The friction system 100 also comprises a socket joint 4 integral with the toothed part 3, which has a second support surface 42 for cooperating with the second fastening element 7. This second support surface 42 is designed to receive the second fastening element 7 pressed onto the arbor 1 and to cooperate with the second fastening element 7. The second support surface 42 therefore forms a second friction surface of the friction system 100 between the first toothed part 3 and the second fastening element 7.

[0031] According to the exemplary embodiment shown in Figures 1 to 3, the socket joint 4 is made integral with the first toothed part 3. In this exemplary embodiment, the socket joint 4 projects opposite the lower surface that presses the annular support surface 20 of the annular flange 2 against the plate of the first toothed part 3.

[0032] For example, the socket joint 4 is reamed with a conical bore having a conical inner surface that is inclined towards the longitudinal axis L of the arbor 1. The conical inner surface of the socket joint 4 forms the second bearing surface 42 of the friction system 100 according to the present invention.

[0033] Other reaming geometries, which are not necessarily linear, are possible without departing from the scope of the invention, as long as the inner surface of the reaming hole has a profile that slopes towards the longitudinal axis L of the arbor 1. However, a conical profile with a linear slope is preferred.

[0034] The second fixing element 7 of the friction system 100 comprises a body 72 having a central opening 73 and a resilient bracket 71 protruding relative to the body 72 in the peripheral region of the body 72. The resilient bracket 71 extends in a direction substantially parallel to the longitudinal axis L. The body 72 is attached to the arbor 1 via the central opening 73, preferably by pushing.

[0035] The elastic bracket 71 has a free end 74 configured to elastically press against the second support surface 42 of the socket joint 4 .

[0036] The free end 74 of the resilient bracket 71 can have various shapes, for example a rounded shape as shown in Figure 4 or a beveled shape as shown in Figure 5. The beveled shape advantageously increases the contact surface between the resilient bracket 71 and the second, preferably conical, support surface 42 of the socket joint 4 and thus the friction torque of the friction system 100.

[0037] 3, when the friction system 100 is assembled, the free end 74 of the elastic bracket 71 is constrained by the geometry of the second support surface 42 and deforms more or less elastically towards the inside of the system, i.e. towards the axis L, depending on the axial position of the fixing element 7 relative to the first toothed part 3. The elastic strain due to the deflection of the elastic bracket 71 is more or less proportional to the strain relative to the first toothed part 3.

[0038] In this way, the friction torque of the friction system 100 according to the present invention is generated to a greater or lesser extent depending on the position at which the second fixing element 7 is pressed into the arbor 1 and thus depending on the strain that the elastic bracket 71 exerts on the socket joint 4.

[0039] According to the invention, the friction torque can be fully adjusted by precisely pressing the second locking element 7 into the arbor 1, and the strain on the socket joint 4 due to the elastic deformation of the elastic bracket 71 makes it possible to obtain a very precise friction torque due to the gradual and controllable generation of the friction torque as the second locking element 7 is pressed in. This makes it easy to precisely set the required friction torque depending on the position of the second locking element 7 relative to the first toothed part 3. Furthermore, the setting of the friction torque is repeatable, as it is largely independent of the manufacturing tolerances of the various components of the friction system 100.

[0040] The strain exerted by the elastic bracket 71 can therefore be adjusted by acting on the relative spacing between the second fixing element 7 and the first toothed part 3, more particularly between the second fixing element 7 and the second, preferably conical, support surface 42 of the socket joint 4 along the longitudinal axis L, thereby adjusting the friction torque that the system can withstand before the first toothed part 3 pivots relative to the arbor 1. Such a design makes the setup very simple and easily reproducible.

[0041] Thus, when the component assembly is mounted, the elastic bracket 71 of the second fixing element 7 forms a kinematic linkage both between the first fixing element 2 and the first toothed component 3 and between the second fixing element 7 and the toothed component 3 via the socket joint 4 up to a predetermined friction torque at the height of the toothed component 3.

[0042] Preferably, the second fixing element 7 has at least three resilient brackets 71 to provide a good distribution of forces.

[0043] Preferably, the second fixing element 7 has four resilient brackets 71, as shown in FIGS.

[0044] Preferentially, the resilient brackets 71 are uniformly distributed around the body 72 at the same angular distance from each other to provide a good distribution of the forces due to pressure on the conical support surface 42 of the socket joint 4.

[0045] 1 to 3, four resilient brackets 71 are arranged at 90° intervals. If there are more resilient brackets, for example six, they are arranged at 60° intervals.

[0046] According to a second exemplary embodiment of the present invention shown in Figures 6 to 7, the socket joint 4 is a part that is attached to and pressed directly into the first toothed part 3 in order to fix the socket joint 4 to the toothed part 3.

[0047] For example, the first toothed part 3 is supported by a plate of the toothed part 3 and comprises a male part (e.g., a dimple, post, sleeve, lug, etc.) designed to cooperate with a female part (e.g., a counterbore, slot, reamed hole) provided in the socket joint 4.

[0048] Of course, the positions of the male and female parts can be reversed so that the first toothed part 3 has a female part formed on its plate and the socket joint 4 supports the male part.

[0049] In the exemplary embodiment shown in Figures 6 and 7, the first toothed part 3 comprises a tubular receiver 31 and the socket joint 4 has a reamed hole 44 configured to cooperate with the tubular receiver 31 by pushing it in.

[0050] In particular, this second embodiment allows for greater freedom in dimensioning the diameter of the socket joint 4 and thus the extent of the second support surface 42, without the rate associated with the operation of the watch movement 200 and the dimensional constraints of the teeth of the first toothed part 3.

[0051] This second embodiment makes it possible to increase the friction torque of such a friction system 100, in particular by increasing the diameter of the socket joint 4 and the second fixing element 7, and thereby increasing the number of elastic brackets 71 on the periphery of the body 72 that come into contact with the second support surface 42 and create friction. This exemplary embodiment is therefore preferred when a high friction torque is required.

[0052] Figure 8 shows a variant embodiment of a friction system 100 according to the invention. This variant embodiment is shown with a socket joint 4 pressed into the first toothed part 3, but this variant embodiment is also applicable to a socket joint 4 made in one piece with the first toothed part 3, as described above with reference to Figures 1 to 3.

[0053] In this modified embodiment, the socket joint 4 has an outer bearing surface formed around the periphery of the socket joint 4, which outer bearing surface forms the second bearing surface 42 of the friction system 100 according to the present invention. The outer bearing surface slopes outward from the socket joint 4.

[0054] Preferentially, the outer bearing surface is a conical surface, but other shapes are possible without departing from the context of the invention.

[0055] Thus, in this embodiment, the elastic bracket 71 elastically deforms towards the outside of the system 100, i.e. away from the axis L relative to the neutral locking position of the elastic bracket 71, when the second fixing element 7 is pressed more or less onto the arbor 1.

[0056] Such a modification facilitates lubrication of the support surface 42, which is the contact surface with the elastic bracket 71. Such a modification also has the effect of multiplying the friction torque, since as the second fixing element 7 is pressed in, the contact point between the elastic bracket 71 and the support surface 42 becomes increasingly farther radially from the center of the arbor 1.

[0057] The friction system 100 according to the present invention is, for example, a friction system for setting the time of a clock movement 200 .

[0058] The invention also relates to a timepiece movement 200 comprising a friction system 100 according to the invention, and to a timepiece 300 comprising such a timepiece movement 200.

[0059] The present invention provides a method for assembling a friction system according to the present invention, comprising the steps of: providing an arbor 1; - pushing the first fixing element 2 onto the shaft 1 into a predetermined axial position; sliding the first toothed part 3 on the shaft 1 up to the first fixing element 2 so that the first toothed part 3 comes into contact with the first fixing element 2, the first toothed part 3 being integral with the socket joint 4; gradually pushing the second fixing element 7 with the elastic bracket 71 directed towards the socket joint 4 onto the arbor 1, compressing the elastic bracket 71 against the socket joint 4 and obtaining a frictional kinematic linkage both between the first fixing element 2 and the first toothed part 3 and between the third fixing element 7 and the socket joint 4 integral with the toothed part 3 until a predetermined friction torque is obtained; The present invention relates to a method including the steps of:

[0060] Of course, the invention is not limited to the examples shown and, as will be apparent to those skilled in the art, various variations and modifications are possible without departing from the scope of the invention as defined by the claims.

Claims

1. A friction system (100) for a timepiece movement (200), comprising: an arbor (1) having a longitudinal axis (L) and designed to be attached to said clock movement (200); a first fixed element (2) mounted to rotate integrally with said arbor (1), said first fixed element (2) having a first support surface (40); a second fixed element (7) mounted to rotate integrally with said arbor (1); a toothed part (3) mounted so as to rotate freely on the arbor (1) between the first fixing element (2) and the second fixing element (7); Equipped with Friction system (100) for a timepiece movement (200), characterized in that the toothed part (3) is integral with a socket joint (4) having a second support surface (42), the second fixing element (7) comprises a body (72) configured to rotate integrally with the arbor (1) and a resilient bracket (71) protruding relative to the body (72) and extending towards the toothed part (3), the resilient bracket (71) being resiliently pressed against the second support surface (42) of the socket joint (4), the resilient bracket (71) being designed to elastically deform under strain from the second support surface (42) and to form a kinematic linkage both between the first fixing element (2) and the toothed part (3) and between the second fixing element (7) and the socket joint (4) integral with the toothed part (3) up to a predetermined friction torque.

2. Friction system (100) for a timepiece movement (200) according to claim 1, characterized in that the elastic bracket (71) extends along an axis substantially parallel to the longitudinal axis (L) of the arbor (1).

3. Friction system (100) for a timepiece movement (200) according to claim 1, characterized in that said second bearing surface (42) is a conical bearing surface.

4. Friction system (100) for a watch movement (200) according to claim 1, characterized in that the second bearing surface (42) is an inner bearing surface formed at the level of the reamed hole in the socket joint (4) and inclined towards the longitudinal axis (L) of the arbor (1).

5. Friction system (100) for a timepiece movement (200) according to claim 1, characterized in that the second support surface (42) is an outer support surface formed around the socket joint (4) and inclined outward from the socket joint (4).

6. Friction system (100) for a timepiece movement (200) according to claim 1, characterized in that the elastic brackets (71) are elastically pressed at their free ends (74) against the second support surface 42 of the socket joint (4).

7. Friction system (100) for a clock movement (200) according to claim 6, characterized in that the free end (74) of the elastic bracket (71) has a rounded or beveled shape.

8. Friction system (100) for a timepiece movement (200) according to claim 1, characterized in that the first bearing surface (40) of the first fixing element (2) is flat or conical.

9. Friction system (100) for a timepiece movement (200) according to claim 1, characterized in that said socket joint (4) is made integral with said toothed part (3).

10. Friction system (100) for a timepiece movement (200) according to claim 1, characterized in that the socket joint (4) is a separate part attached to the toothed part (3).

11. Friction system (100) for a timepiece movement (200) according to claim 10, characterized in that the socket joint (4) is pressed into a tubular receptacle (31) of the toothed part (3).

12. A timepiece movement (200) comprising a friction system (100) according to claim 1.

13. 10. A method of assembling a friction system (100) according to claim 1, comprising the steps of: - providing an arbor (1); - forcing the first fixing element (2) onto said shaft (1) into a predetermined axial position; - sliding a first toothed part (3) on the shaft (1) up to the first fixing element (2) so that the first toothed part (3) comes into contact with the first fixing element (2), the first toothed part (3) being integral with a socket joint (4); - gradually forcing a second fixing element (7) with a resilient bracket (71) directed towards the socket joint (4) onto the arbor (1) and compressing the resilient bracket (71) against the socket joint (4) until a predetermined friction torque is obtained, obtaining a friction-kinematic linkage both between the first fixing element (2) and the first toothed part (3) and between the second fixing element (7) and the socket joint (4) integral with the toothed part (3); A method comprising:

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