Barrel for timepiece

Abstract

The invention relates to a barrel (1) for an automatic-winding timepiece, comprising a drum (11) having an axis AA and provided with an inner lateral wall (12), and a main spring (2) forming a winding device comprising an outer ring (21), the end (22) of which is frictionally coupled to the inner lateral wall (12) and free to slide against the inner lateral wall (12) in the event of overwinding of the main spring (2). According to the invention, the end (22) of the outer ring (21) comprises an outer face (23) having two friction surfaces (24, 25) arranged in the top and bottom portions of the outer ring (21) and placed in contact with the inner lateral wall (26) in such a way that the portion between the friction surfaces (24, 25), called the intermediate portion (26), is not in contact with the inner lateral wall (12), the intermediate portion (26) forming a reservoir (27) for lubricant between the two friction surfaces (24, 25).

Description

Technical Field

[0001] This invention belongs to the field of horology. More specifically, it relates to a mainspring barrel intended for equipping an automatic winding timepiece. It also relates to a timepiece equipped with such a mainspring barrel. Background Technology

[0002] The mainspring barrel for automatic timepieces typically comprises a drum containing a mainspring spirally wound around the barrel spool. To prevent any over-tensioning of the mainspring (which could lead to mainspring failure or damage to the gear train of the automatic winding mechanism), the mainspring is not fixed to the side walls of the drum, but rather engaged by friction via a flexible strip called the slip spring, which is frictionally connected by its last coil. The frictional connection between the mainspring and the side walls of the drum must be calculated so that, exceeding a determined maximum drive torque, the last coil slides along said walls and thus reduces the tension of the mainspring. The surface condition and lubrication of the inner side walls of the drum are factors that greatly affect the operation of this frictional connection. Another determining factor involves the geometry of the inner side walls.

[0003] According to existing technology, the inner wall of the drum includes a friction surface against which the end of the mainspring rubs, causing wear on the drum wall. To improve this problem, a lubricant such as grease is deposited on the inner wall of the drum.

[0004] However, wear is a persistent problem that worsens over time and can lead to serious damage, malfunction, or even breakage of parts. In fact, friction at the end of the mainspring's last coil often scrapes off the grease and pushes it back onto the upper and lower edges of the drum. Eventually, the end of the outer coil tears fine particles from the drum wall, and these particles further abrade the friction, generating even more particles and accelerating wear. Over time, the frictional bond between the mainspring and the side walls of the mainspring barrel can be severely affected.

[0005] Therefore, removing the spring barrel and adding grease remains necessary to maintain satisfactory operating conditions.

[0006] Therefore, one object of the present invention is to provide a spring barrel that can improve this wear problem. Summary of the Invention

[0007] The present invention solves the above-mentioned defects by proposing a mainspring barrel including a mainspring, wherein the outer ring of the mainspring includes a structure with two friction surfaces arranged in the top and bottom portions of the outer ring, the friction surfaces being arranged to contact the inner wall of the mainspring barrel.

[0008] Therefore, the present invention relates to a mainspring barrel for an automatic winding timepiece, the mainspring barrel comprising a drum and a mainspring, the drum having an axis AA and an inner sidewall, the mainspring forming a winding device including an outer ring, the end of the outer ring being frictionally engaged with the inner sidewall and sliding freely against the inner sidewall in the event of over-tensioning of the mainspring.

[0009] According to the invention, the end of the outer ring includes an outer surface having two friction surfaces disposed in the top and bottom portions of the outer ring and arranged to contact the inner sidewall, such that a portion between the friction surfaces, referred to as the intermediate portion, does not contact the inner sidewall, the intermediate portion forming a reservoir for lubricant between the two friction surfaces and allowing lubricant to be directed to the middle of the outer ring.

[0010] Other advantageous variations according to the invention:

[0011] - The friction surface is in the form of localized thickenings in the top and bottom portions of the outer ring;

[0012] - The friction surface is formed by removing a portion or the entire thickness of the outer ring at the middle part of the outer ring;

[0013] - The friction surface extends along the length of the outer ring;

[0014] - The thickness of the material removal section varies from the end of the outer ring and increases along the length of the outer ring;

[0015] - The material removal section is in the form of a funnel, neck, parabola, or semicircle, or any other geometry that can guide the grease to the middle of the friction track of the strip against the drum.

[0016] The present invention also relates to a watch movement comprising a mainspring barrel according to the invention.

[0017] The present invention also relates to a watch comprising a movement equipped with a mainspring barrel according to the present invention. Attached Figure Description

[0018] Figure 1 The mainspring of the mainspring barrel according to the present invention is shown;

[0019] Figure 2 A drive mechanism including a spring barrel according to the invention is shown;

[0020] Figures 3a to 3d The end of the outer ring of the mainspring in the mainspring barrel according to the present invention is shown. Detailed Implementation

[0021] The following will be referenced together. Figure 1 , Figure 2 and Figures 3a to 3d The spring box according to the present invention is described.

[0022] like Figure 2 The mainspring barrel 1, as shown in the diagram, for an automatic winding watch movement includes a back cover 10 integrated with a drum 11 having an axis AA. The mainspring 2 (also shown in the diagram) Figure 1 The mainspring 2 is wound inside the mainspring barrel 1. The inner ring 20 of the mainspring 2 is connected to the core 4 provided on the winding shaft 5, and the outer ring 20 of the mainspring 2 is in contact with the inner side wall 12 of the drum 11.

[0023] The mainspring 2 can be made as a single piece and in the form of a strip. The mainspring can therefore be mounted on the core 4 around the spool 5 of the mainspring barrel.

[0024] The outer ring 21 has an end 22 that is frictionally engaged with the inner wall 12 and can slide freely along the inner wall 12 in the event of over-tensioning of the mainspring 2.

[0025] like Figure 2 As can be observed, the drive mechanism 100 has a spring barrel 1, which includes a cylindrical drum 11 in which a spring 2 is housed, a spring barrel shaft 5 and a core 4 on which the inner ring 20 of the spring 2 is fixed, and a cover 6 for closing the drum 11.

[0026] The drum 4 also includes an external gear train 13, which meshes with a pinion (not shown) in the gear train of the moving parts.

[0027] According to the invention, the end 22 of the outer ring 21 includes an outer surface 23 having two friction surfaces 24, 25 disposed in the top and bottom portions of the outer ring 21 and arranged to contact the inner wall 12, such that a portion called the intermediate portion 26 between the friction surfaces 24, 25 does not contact the inner wall 12.

[0028] Advantageously, the intermediate portion 26 forms a reservoir for lubricant, which is located at least partially between the two friction surfaces 24, 25.

[0029] As shown, friction surfaces 24 and 25 are formed by removing a portion or the entire thickness of material from the outer ring 21 at the intermediate portion 26. This material removal allows friction surfaces 24 and 25 to contact the inner wall 12 of the drum; as the outer ring 21 slides against the drum, the material removal carries the lubricant towards the center.

[0030] According to another embodiment of the invention, the friction surfaces 24, 25 are in the form of local thickenings on the top and bottom portions of the outer ring 21, so that only the thickenings contact the inner wall 12 of the drum and form a reservoir for lubricant in the middle portion of the outer ring 21.

[0031] Friction surfaces 24 and 25 extend along the length of the outer ring 21, the length of which can obviously be varied according to the needs of those skilled in the art. It is also obvious that friction surfaces 24 and 25 do not extend along the entire length of the outer ring 21, so as not to make it brittle or too rigid, which would also be detrimental to the proper operation of the spring barrel.

[0032] according to Figure 3d In one embodiment illustrated in the figure, the thickness of the material removal section varies from the end of the outer ring 21 and increases along the length of the outer ring. For example, the material removal section is in the form of a funnel, neck, parabola, or semicircle, in such a way as to form a reservoir for lubricant and guide the lubricant toward the center of the inner wall of the drum.

[0033] Also according to Figure 3b In another embodiment illustrated in the figure, the end 22 of the outer ring 21 is deformed at its outer surface 23 in such a way as to form two friction surfaces 24, 25. For example, such deformation of the outer ring 21 is obtained by stamping.

[0034] Furthermore, this arrangement at the end of the outer ring allows for the uniform distribution of lubricant from the very beginning of the spring barrel's operation, and subsequently enables the lubricant to be directed to the center of the outer ring.

[0035] The present invention also relates to a watch movement and timepiece equipped with a mainspring barrel according to the present invention.

[0036] As a result of these various aspects of the present invention, we have a mainspring barrel that reduces wear caused by friction between the mainspring and the mainspring barrel drum.

[0037] Of course, the present invention is not limited to the illustrated examples and various variations and modifications that will be obvious to those skilled in the art.

Claims

1. A mainspring barrel (1) for an automatic winding timepiece, the mainspring barrel (1) comprising a drum (11) and a mainspring (2), the drum (11) having an axis AA and an inner wall (12), the mainspring (2) forming a winding device including an outer ring (21), the end (22) of the outer ring (21) being frictionally connected to the inner wall (12) and sliding freely against the inner wall (12) in the event of over-tensioning of the mainspring (2), characterized in that, The end (22) of the outer ring (21) includes an outer surface (23) having two friction surfaces (24, 25) disposed in the top and bottom portions of the outer ring (21) and arranged to contact the inner sidewall (12) in such a way that a portion called the middle portion (26) between the friction surfaces (24, 25) does not contact the inner sidewall (12), the middle portion (26) forming a reservoir (27) for lubricant between the two friction surfaces (24, 25) and enabling lubricant to be directed to the middle of the outer ring (21).

2. The spring barrel (1) according to claim 1, characterized in that, The friction surfaces (24, 25) are in the form of local thickenings in the top and bottom portions of the outer ring (21).

3. The spring box (1) according to claim 1 or 2, characterized in that, The friction surfaces (24, 25) are formed by removing a portion or the entire thickness of the outer ring at the middle portion of the outer ring (21).

4. The spring barrel (1) according to claim 1 or 2, characterized in that, The friction surface extends along the length of the outer ring.

5. The spring barrel (1) according to claim 3, characterized in that, The thickness of the material removal section varies from the end of the outer ring and increases along the length of the outer ring.

6. The spring barrel (1) according to claim 3, characterized in that, The material removal section is funnel-shaped.

7. The spring barrel (1) according to claim 3, characterized in that, The material removal section is in the form of a neck.

8. The spring barrel (1) according to claim 3, characterized in that, The material removal section is in the form of a parabola.

9. The spring barrel (1) according to claim 3, characterized in that, The material removal section is in a semi-circular shape.

10. A movement comprising a mainspring barrel (1) according to any one of claims 1 to 9.

11. A timepiece comprising the movement according to claim 10 and / or the mainspring barrel (1) according to any one of claims 1 to 9.

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