This application claims priority of European patent application No. EP17192975.5 filed Sep. 25, 2017, which is hereby incorporated by reference herein in its entirety, and this application claims priority of European patent application No. EP17192977.1 filed Sep. 25, 2017, which is hereby incorporated by reference herein in its entirety.

BACKGROUND

The invention relates to a cage for separating rolling bodies of a bearing or a cage for separating rolling bodies for a bearing. The invention also relates to a bearing, particularly a bearing comprising such a cage. The invention further relates to a timepiece mechanism comprising such a bearing or such a cage. The invention also relates to a timepiece movement comprising such a movement or such a bearing or such a cage. The invention further relates to a timepiece comprising such a movement or such a mechanism or such a bearing or such a cage. The invention also relates to a method for producing such a bearing or such a mechanism or such a movement or such a timepiece.

Bearings, in particular ball bearings, are currently used in the field of watchmaking, particularly for implementing the pivoting of movable elements such as oscillating weights of automatic winding movements. Indeed, the advantage of a bearing is that it allows rapid rotation of a movable element with minimum friction, while supporting significant axial and/or radial loads, whilst providing precise positioning of said movable element.

Patent application EP1520111 discloses a ball bearing with four contact points, the architecture of which is well known from the prior art. This bearing comprises a predetermined number of balls disposed in a cage, which is disposed between an outer ring and an inner ring formed by two washers that are fixed together. According to the teaching of this document, lubricating a timepiece bearing raises various problems with respect to, on the one hand, the difficulty of controlling the suitable quantity of lubricant and, on the other hand, possible drops in performance of said bearing. The document thus proposes implementing balls made of zirconium oxide ceramic, so as to propose a bearing that does not require lubrication.

Patent application CH709348 discloses a ball bearing architecture similar to that of the bearing of document EP1520111. The document describes a cage having a circular crown shape provided with cutaways in the vicinity of its outer periphery, which cutaways are provided to receive the balls. Like the single figure of the specification of patent EP1520111, document CH709348 describes a contact surface or a consequential potential contact surface between the cage and the inner ring of the bearing.

Patent application EP2787234 discloses a ball bearing architecture that slightly differs from that of the bearings of documents EP1520111 and CH709348, with a one-piece inner ring and an outer ring formed by two washers. In this case, the cage is in the form of a circular crown provided with cutaways in the vicinity of its inner periphery, which cutaways are provided to receive the balls. The document also describes a contact surface or a consequential potential contact surface between the cage and the outer ring of the bearing.

Patent application CH711020 relates to an alternative architecture of ball bearings. This implements one-piece inner and outer rings, between which a cage is disposed in the form of a hollow cylinder. This cage is provided with cutaways in the vicinity of one of the axial ends thereof, which cutaways are provided to receive the balls. During conventional operation of such a roller bearing, play remains between the cage and the rings, particularly the inner ring. However, an impact can cause contact between the cage and either of the two rings, particularly the inner ring. Like the preceding constructions, a consequential potential contact surface thus exists between the cage and the inner or outer ring of the bearing.

Furthermore, ball bearings exist that are devoid of a cage. By way of an example, the manufacturer MPS proposes a “full complement ball bearing” known commercially as “Myrox14”. This bearing is formed by inner and outer rings made of zirconium oxide type ceramic and comprises balls also made of the same material.

SUMMARY

Various documents stipulate that timepiece bearings must not be lubricated due to the aforementioned disadvantages.

However, studies by the applicant show that the operating noise of an unlubricated bearing does not meet their performance criteria. Indeed, the operation of a bearing can cause a noise that can be heard by a horologist or even by a wearer of a wrist watch incorporating such a bearing, particularly when new or after several years of operation.

The aim of the invention is to provide a cage for separating rolling bodies of a bearing or a bearing allowing the aforementioned disadvantages to be overcome and the known devices of the prior art to be improved. In particular, the invention proposes a bearing, which may or may not be provided with a separation cage, that is quiet and for which performance over time remains stable.

According to a first aspect of the invention, a cage for a bearing is determined by the following definitions.

1. A cage for separating rolling bodies for a bearing, particularly for a timepiece bearing, the cage having first openings for receiving rolling bodies and at least one first contact zone intended to come into contact with a bearing ring and having at least one first hollow formation.

2. The cage according to definition 1, wherein the cage has a substantially flat annular shape or wherein the cage has a substantially cylindrical shape.

3. The cage according to one of definitions 1 and 2, wherein the cage comprises a first edge and a second edge, the first openings being openings emerging on the first edge or on the second edge and/or the at least one first hollow formation comprises at least one second opening passing through a thickness of the cage.

4. The cage according to definition 3, wherein the cage has a substantially flat annular shape, the first edge being an outer edge and the second edge being an inner edge, or wherein the cage has a substantially cylindrical shape, the first edge being an edge of a first end and the second edge being an edge of a second end.

5. The cage according to one of definitions 1 to 4, wherein it comprises a plurality of hollow formations, particularly a plurality of second openings, each disposed between two first adjacent openings.

6. The cage according to one of definitions 1 to 5, wherein the contact zone comprises at least one first projecting formation, a top of which is intended to participate in a cage-bearing ring interface.

7. The cage according to definition 6, wherein the at least one first projecting formation comprises a rib of circular or substantially circular shape and/or wherein the at least one first projecting formation comprises a set of bosses, particularly at least three bosses, in particular at least three bosses disposed circularly or substantially circularly and/or at least three bosses disposed at a regular or substantially regular angular interval relative to an axis of the cage.

8. The cage according to one of definitions 1 to 7, wherein the cage is arranged so that the area of a surface of the cage capable of coming into contact with a bearing ring is less than 0.6 or 0.5 or 0.45 or 0.4 or 0.3 times the area of:the orthogonal projection of the cage along an axis of the cage, particularly an axis of rotational symmetry of the cage, when the cage is a flat annular cage; orthe cylindrical surface of a cylinder having a diameter equal to that of the diameter of the cylinder defining the surface of the cage and included between two end edges of the cage when the cage is a cylindrical cage.

According to the first aspect of the invention, a bearing is determined by the following definitions.

9. A bearing, particularly a timepiece bearing, comprising a first ring, particularly an inner ring, a second ring, particularly an outer ring, rolling bodies and a cage for separating rolling bodies, particularly a separation cage according to one of definitions 1 to 8, the cage and the first and second rings being arranged so that the area of a surface of the cage capable of coming into contact with the rings is less than 0.6 or 0.5 or 0.45 or 0.4 or 0.3 times the area of:the orthogonal projection of the cage along an axis of the bearing when the cage is a flat annular cage; orthe cylindrical surface of a cylinder having a diameter equal to that of the diameter of the cylinder defining the surface of the cage and included between two end edges of the cage when the cage is a cylindrical cage.

10. The bearing according to definition 9, wherein a surface of one of the first and second rings comprises at least one second contact zone having at least one second hollow formation and/or at least one second projecting formation, the top of which participates in a cage-ring interface.

11. The bearing according to definition 10, wherein the at least one second projecting formation comprises a circular or substantially circular shaped rib and/or wherein the at least one second projecting formation comprises a set of bosses, particularly at least three bosses, in particular at least three bosses disposed circularly or substantially circularly and/or at least three bosses disposed at a regular or substantially regular angular interval relative to an axis of the bearing.

12. The bearing according to one of definitions 9 to 11, wherein it comprises at least one surface of the first ring and/or of the second ring and/or of a rolling body coated with a lubricant, particularly a lubricant with kinematic viscosity at a temperature of 20° C. that is between 8 and 15 St, in particular equal to 10 St or approximately equal to 10 St and/or wherein the first ring comprises a first annular element and a second annular element, the first and second annular elements being shaped so as to provide, when they are assembled, a groove for accommodating the cage and/or wherein the rolling bodies are balls or needles or rollers, particularly cylindrical or tapered rollers and/or wherein the rolling bodies are made of ceramic, particularly made of zirconium oxide or silicon nitride.

According to the first aspect of the invention, a mechanism is determined by the following definition.

13. A timepiece mechanism, particularly an oscillating weight device or an automatic winding device, comprising a bearing according to one of definitions 9 to 12 or a cage according to one of definitions 1 to 8.

According to the first aspect of the invention, a movement is determined by the following definition.

14. A timepiece movement comprising a cage according to one of definitions 1 to 8 or a bearing according to one of definitions 9 to 12 or a mechanism according to definition 13.

According to the first aspect of the invention, a timepiece is determined by the following definition.

15. A timepiece, particularly a wrist watch, comprising a movement according to definition 14 or a cage according to one of definitions 1 to 8 or a bearing according to one of definitions 9 to 12 or a mechanism according to definition 13.

According to the first aspect of the invention, a method is determined by the following definitions.

16. A method for producing a timepiece bearing or a timepiece mechanism or a timepiece movement or a timepiece, the method comprising the following steps:providing a bearing according to one of definitions 9 to 12;applying, on at least one surface of the first ring and/or of the second ring and/or of a rolling body, a lubricant, particularly a lubricant with kinematic viscosity at a temperature of 20° C. that is between 8 and 15 St, in particular equal to 10 St or substantially equal to 10 St.

17. The method according to definition 16, wherein the lubricant is applied by jetting or by contactless spraying.

According to a second aspect of the invention, a bearing is determined by the following definitions.

18. A timepiece bearing, comprising a first ring, particularly an inner ring, a second ring, particularly an outer ring, and rolling bodies, the bearing comprising at least one surface of the first ring and/or of the second ring and/or of a rolling body coated with a lubricant.

19. The bearing according to definition 18, wherein the kinematic viscosity of the lubricant at a temperature of 20° C. is between 8 and 15 St, in particular equal to 10 St or approximately equal to 10 St.

20. The bearing according to definition 18 or 19, wherein the bearing does not comprise a cage for separating rolling bodies or wherein the bearing is of the type with integral rolling bodies, particularly of the full complement ball bearing type, or wherein the rolling bodies are capable of coming into contact with each other.

21. The bearing according to one of definitions 18 to 20, wherein the first ring comprises a first annular element and a second annular element, the first and second annular elements being shaped so as to provide, when they are assembled, a groove for accommodating the cage.

22. The bearing according to one of definitions 18 to 21, wherein the rolling bodies are balls or needles or rollers, particularly cylindrical or tapered rollers.

23. The bearing according to one of definitions 18 to 22, wherein the rolling bodies are made of:ceramic, particularly made of zirconium oxide or silicon nitride, orsteel, notably a bearing steel, such as a low-alloy steel containing Cr, for example 100Cr6 (DIN 1.3505) or 100CrMo7-3 (DIN 1.3536), orsuperelastic alloy such as Nitinol.

24. The bearing according to one of definitions 18 to 23, wherein the first ring is made of steel or a stainless steel, for example a 4C27A (DIN 1.4197), or a superelastic alloy such as Nitinol and/or wherein the second ring is made of steel or a stainless steel, for example a 4C27A, or a superelastic alloy such as Nitinol.

25. The bearing according to one of definitions 18 to 24, wherein the bearing comprises between 25 and 35 rolling bodies or balls, particularly 27 or 28 or 29 or 30 rolling bodies or balls.

26. The bearing according to one of definitions 18 to 25, wherein the balls or rolling bodies are mounted in the rings with a tangential play or clearance, the play being for example higher than the radius of the balls or rolling bodies or equal to the radius of the balls or rolling bodies and/or the play being for example lower than the diameter of the balls or rolling bodies or equal to the diameter of the balls or rolling bodies.

According to the second aspect of the invention, a mechanism is determined by the following definitions.

27. A timepiece mechanism, particularly an oscillating weight device or an automatic winding device, comprising a bearing according to one of definitions 18 to 26.

28. The timepiece mechanism according to definition 27, wherein it comprises an oscillating weight, the static torque of which is greater than or equal to 120 μNm or 180 μNm or 220 μNm or 250 μNm and/or the oscillating weight weighing more than 2 g or 3 g or 4 g.

According to the second aspect of the invention, a movement is determined by the following definition.

29. A timepiece movement comprising a bearing according to one of definitions 18 to 26 or a mechanism according to definition 27 or 28.

According to the second aspect of the invention, a timepiece is determined by the following definition.

30. A timepiece, particularly a wrist watch, comprising a movement according to definition 29 or a bearing according to one of definitions 18 to 26 or a mechanism according to definition 27 or 28.

According to the second aspect of the invention, a method is determined by the following definitions.

31. A method for producing a timepiece bearing or a timepiece mechanism or a timepiece movement or a timepiece, the method comprising the following steps:providing a bearing comprising a first ring, particularly an inner ring, a second ring, particularly an outer ring and rolling bodies;applying a lubricant, on at least one surface of the first ring and/or of the second ring and/or of a rolling body.

32. The method according to definition 31, wherein the kinematic viscosity of the lubricant at a temperature of 20° C. is between 8 and 15 St, in particular equal to 10 St or substantially equal to 10 St.

33. The method according to definition 31 or 32, wherein the lubricant is applied by jetting or by contactless spraying.

Unless logically or technically incompatible, any combination of the features of the first and second aspects can be made.

