CH716332A1 - Pivot watch shaft. - Google Patents

Abstract

The invention relates to a clockwork shaft (1) for the rotational mounting of at least one member comprising a bearing surface (22) intended to receive the member and a pivot (21) at each of its two free ends intended to pivot in a bearing to make the member rotatable. According to the invention, at least one of the two pivots (21) comprises a structuring (25) of its external surface in order to minimize its contact surface with the bearing.

Description

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a watch shaft of which at least one of the pivots is improved in order to improve its tribology in a bearing.

TECHNICAL BACKGROUND OF THE INVENTION

[0002] It is constantly sought to minimize the coefficients of friction in watch movements. In the case of watch shafts, the lowest possible loss of mechanical energy due to friction is thus sought.

SUMMARY OF THE INVENTION

[0003] The object of the invention is to provide a watch shaft, the tribology of which in a bearing is improved in order to reduce the losses of mechanical energy.

To this end, the invention relates to a watch shaft for the rotational mounting of at least one member comprising a bearing surface intended to receive the member and a pivot at each of its two free ends intended to pivot in a bearing to make the member movable in rotation, characterized in that at least one of the two pivots comprises a structuring of its external surface in order to minimize its contact surface with the bearing.

Advantageously according to the invention, the contact surface of the watch shaft with the bearing, such as the wall of the hole of a bearing, can therefore be modified in order to adjust the associated mechanical energy losses. In combination with a lubricant, it is also desired that the structuring provides an effect of lifting the lubricant and recirculating the lubricant on the surface of the pivot. It is therefore understood that the structuring advantageously makes it possible to reduce the coefficient of friction and the wear of the pivot against the bearing.

[0006] The invention may also include one or more of the following optional characteristics, taken alone or in combination.

[0007] The structuring may include at least one recessed pattern in the external surface of the pivot in order to selectively modify the contact surface of the watch shaft with the bearing. A capillary effect is also sought to retain any lubricant at the level of the pivot thanks to the structuring.

[0008] The hollow pattern of the structuring may have a width L of between 300 nm and 1 μm. In addition, the recessed pattern may have a width to depth ratio of between 5 and 20.

[0009] The structuring can, for example, represent between 5% and 50% of the external surface of the pivot and, preferably, 30% in order to reduce the contact surface of the watch shaft with the bearing.

The structuring can form at least one groove in order to form a circulation channel for a lubricant on the external surface of the pivot and / or at least one recess in order to form a reservoir for a lubricant on the external surface of the pivot.

[0011] The shaft may comprise tapered pivot ends, a cylindrical base of at least one of the two pivots, called the contact surface, comprising a structuring of its external surface in order to selectively differentiate the coefficient of friction of the surface of contact with that of the tapered end of the shaft pivot. This particular example applied to a balance pin advantageously makes it possible to minimize the differences in amplitude of the balance between the horizontal and vertical positions.

Finally, the invention relates to a watch movement comprising at least one bridge and a plate each provided with bearings and at least one watch shaft assembled between a bearing of the bridge and a bearing of the plate in order to be pivotally mounted , characterized in that the watch tree is as presented above. In no way limiting, the watch shaft can be a balance axis, an anchor rod, a toothed wheel shaft and / or a barrel shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the accompanying drawings, in which:

- Figure 1 is a schematic view of a timepiece according to the invention;

- Figure 2 is a perspective view of a watch tree with a structure according to the invention;

- Figures 3a to 3c are schematic views of the structuring of a pivot according to a first embodiment of the invention;

- Figures 4a to 4c and 5a to 5d are schematic views of the structuring of a pivot according to a second embodiment of the invention;

- Figures 6a to 6d are schematic views of the structuring of a pivot according to the first and second combined embodiments of the invention;

- Figure 7 is a partial schematic sectional view of a shaft assembled in a bearing;

- Figure 8 is a partial schematic view of an escapement mechanism of a watch movement. ;

- Figure 9 is a partial schematic view of a resonator of a watch movement.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

In the various figures, identical or similar elements bear the same references, optionally added to an index. The description of their structure and function is therefore not systematically repeated.

In what follows, the orientations are the orientations of the figures. In particular, the terms ..uperior "," lower ", ..left", "right", .. above "," below "," forwards "and ..backwards" are generally understood in relation to the sense of representation of the figures.

By "timepiece 2" is meant all types of measuring or time-counting instruments such as clocks, clocks and watches.

By ..mouvement 3 horloger ", we mean all types of mechanism capable of counting the time they are powered based on mechanical energy (for example a barrel) or electric (for example a battery).

The invention relates to a shaft 1 for a watch movement 3 intended to equip a timepiece 2 as illustrated in Figure 1. An example of a watch movement 3 is partially shown in Figure 7. It can thus include at least one bridge 5 and one plate 6 each provided with bearings 7. It also comprises at least one watchmaker shaft 1 assembled between a bearing 7 of the bridge 5 and a bearing 7 of the plate 6 (only one end is illustrated in FIG. 7 for simplicity) in order to be pivotally mounted between the bridge 5 and the plate 6.

A bearing 7 generally comprises a body 8 in which is mounted a bearing 9 whose hole 10 receives the pivot 21 of the shaft 1. In the example of Figure 7, the bearing 7 further comprises a kitten 12 mounted elastically in the body 8 of the bearing 7, for example, using a spring (not shown) sometimes called a lyre. The kitten 12 supports the pad 9 and a counter-pivot 11 and can by its resilient mounting dampen the shocks received by the pivots 21 of the shaft 1. Such an arrangement is generally called a bumper or parachute bearing. The bearing 9 and the counter-pivot 11 are generally based on ruby and, as such, can sometimes be called respectively stone 9 and counter-pivot stone 11. Of course, other types of bearings can be provided, such as a crapaudine. but also other types of materials than ruby. The bearing 7 could thus be all or part formed of a ceramic and / or a carbon-based material.

In no way limiting in the examples of Figures 8 and 9, the watchmaker's shaft 1 can thus form a balance axis A 13, an anchor rod B 17, a toothed wheel shaft C 18 and / or a barrel shaft (not shown) of a watch movement 3. An example of a watchmaker's shaft 1 is shown in FIG. 2. As explained above, the watchmaker's shaft 1 can be used for the rotational mounting of at least one member such as a balance 13, a hairspring 14, a large plate 15, a small plate 16, an anchor 17, a toothed wheel 18, a pinion 19 and / or a barrel spring (not shown) of a watch movement 3.

The watchmaker shaft 1 can thus include a bearing surface, also called seat 22, intended to receive the organ, rods 23, a rod 24 and a pivot 21 at each of its two free ends intended to pivot in a bearing 7 to make the organ mobile in rotation. Such a shaft 1 is generally formed from steel such as, for example, type 20AP.

Of course, other geometries of shafts can be provided depending on the application and the number of members to be received. The bearing 22 intended to receive the member could thus be formed by another part of the shaft 1. Thus, in no way limiting, the bearing could not be a seat 22 but by one of the rods 23. In addition, d other types of materials than steel can be considered. The shaft 1 could thus be all or part formed of a ceramic and / or a carbon-based material (DLC or diamond) and / or any other material not very sensitive to magnetic fields such as for example molybdenum disulphide (MoS2) or tungsten disulfide (WS2).

According to the invention, at least one of the two pivots 21 comprises a structuring 25 of its outer surface 26 in order to minimize its contact surface with the bearing 7 and, more particularly the wall of the hole 10 of the bearing 9. Advantageously according to the invention, the contact surface of the watch shaft 1 with the bearing 7, such as the wall of the hole 10 of a bearing 9, can therefore be modified in order to adjust the associated mechanical energy losses. A capillary effect is also sought to retain the oil or the lubricant at the level of the pivot 21 by virtue of the structuring 25.

The structuring 25 may include at least one recessed pattern 27 on the outer surface 26 of the pivot 21 in order to selectively modify the contact surface of the watchmaker shaft 1 with the bearing 7. The pattern 27 extends over a angular sector of the pivot 21 and thus forms an indentation having a width L, a depth and a length. It should thus be understood that from a usual shaft 1 with a conical pivot 21 that the structuring 25 can be obtained in a destructive manner, that is to say by selectively hollowing out the material of the pivot 21 (laser radiation, attack chemical, etc.), or additionally, that is to say by selectively depositing a material on the pivot 21 (electrolytic deposition, physical vapor deposition, etc.), in order to form each pattern 27 recessed on the surface 26 external of the pivot 21.

Whether in overlay or in the material of the shaft 1, the structuring 25 represents, preferably, between 5% and 50% of the external surface 5 of the pivot 21 and, preferably, 30% in order to reduce the surface contact of watchmaker shaft 1 with bearing 7.

The recessed pattern 27 of the structuring 25 can form at least one groove 27a in order to form a circulation channel for a lubricant on the outer surface 26 of the pivot 21 and / or at least one recess 27b in order to form a reservoir for a lubricant on the outer surface 26 of the pivot 21. In fact, the bearings 7 are generally lubricated in particular using an oiler 20 at the level of the bearing 9. Thus, the structuring 25 also makes it possible to maintain a more uniform film. lubricant on the outer surface 26 of the pivot 21.

According to a first embodiment, the pivot 21 comprises a structure 25 formed solely on the basis of at least one recess 27a in order to form reservoirs distributed homogeneously or not on the outer surface 26 of the pivot 21. As such in no way limiting, FIGS. 3a to 3c are examples of the first embodiment according to the invention. In the first variant illustrated in FIG. 3a, the pivot 21 comprises a structure 25 formed of recesses 27a of substantially rectangular sections distributed all around the outer surface 26. Each recess 27a is oriented substantially parallel with respect to the length of the shaft 1. In the second variant illustrated in FIG. 3b, the pivot 21 comprises a structure 25 formed of recesses 27a of substantially circular sections distributed all around the surface. 26 external. Finally, in a third variant illustrated in FIG. 3c, the pivot 21 comprises a structuring

25 formed of recesses 27a of substantially rectangular sections distributed all around the outer surface 26. Each recess 27a is oriented substantially perpendicular to the length of the shaft 1.

Of course, the variants of the first embodiment can be combined and / or each recess 27a can be of different geometry to the others and / or the recesses 27a can be distributed in a different way (different density for the same area, different distribution particularly asymmetric, etc.) on the outer surface 26 of the pivot 21.

According to a second embodiment, the pivot 21 comprises a structure 25 formed solely on the basis of at least one groove 27b in order to form circulation channels distributed homogeneously or not on the surface.

26 external of the pivot 21. In no way limiting, FIGS. 4a to 4c and 5a to 5d are examples of the second embodiment according to the invention. In the first variant illustrated in FIG. 4a, the pivot 21 comprises a structure 25 formed of a substantially helical groove 27b on the outer surface 26. In the second variant illustrated in FIG. 4b, the pivot 21 comprises a structure 25 formed of a substantially helical groove 27b and of substantially vertical grooves 27b crossing the substantially helical groove 27b on the outer surface 26. In a third variant illustrated in FIG. 4c, the pivot 21 comprises a structure 25 formed of a first substantially helical groove 27b and of a second substantially helical groove 27b crossing the first substantially helical groove 27b and winding in an inverse manner to the first substantially helical groove 27b on the outer surface 26.

In the fourth variant illustrated in Figure 5a, the pivot 21 comprises a structure 25 formed of grooves 27b in zigzag around the outer surface 26. In the fifth variant illustrated in FIG. 5b, the pivot 21 comprises a structure 25 formed of zigzag grooves 27b extending substantially vertically on the outer surface 26. In a sixth variant illustrated in FIG. 5c, the pivot 21 comprises a structure 25 formed of a first series of grooves 27b zigzag around the outer surface 26 and a second series of grooves 27b zigzag around the surface 26 external intersecting the first series of grooves 27b zigzag around the outer surface 26 and extending out of phase or out of phase with the first series of grooves 27b zigzag around the outer surface 26. In a seventh variant illustrated in FIG. 5d, the pivot 21 comprises a structure 25 formed of a first series of zigzag grooves 27b extending substantially vertically on the outer surface 26 and of a second series of zigzag grooves 27b s 'extending substantially vertically over the outer surface 26 intersecting the first series of zigzag grooves 27b extending substantially vertically over the outer surface 26 and extending offset or out of phase with respect to the first series of zigzag grooves 27b s' extending substantially vertically over the outer surface 26.

Of course, the variants of the second embodiment can be combined and / or each groove 27b can be of different geometry to the others and / or the grooves 27b can be distributed differently (different density for the same surface, different distribution particularly asymmetric, etc.) on the outer surface 26 of the pivot 21.

According to a third embodiment, the pivot 21 comprises a structure 25 formed on the basis of at least one recess 27a in order to form reservoirs distributed homogeneously or not on the outer surface 26 of the pivot 21 and based on 'at least one groove 27b in order to form circulation channels distributed homogeneously or not on the external surface 26 of the pivot 21. In no way limiting, FIGS. 6a to 6d are examples of the third embodiment according to the invention .

In the first variant illustrated in Figure 6a, the pivot 21 comprises a structure 25 formed of a first series of grooves 27b zigzag around the outer surface 26, a second series of grooves 27b zigzag around the outer surface 26 crossing the first series of grooves 27b zigzagging around the outer surface 26 and extending out of phase or out of phase with respect to the first series of grooves 27b zigzagging around the outer surface 26, and recesses 27a of substantially circular sections distributed between two pairs of first and second series of crossed zigzag grooves 27b all around the outer surface 26.

In the second variant illustrated in Figure 6b, the pivot 21 comprises a structure 25 formed of grooves 27b in zigzag around the outer surface 26 and recesses 27a of substantially rectangular sections (extending substantially parallel with respect to the length of the shaft 1) distributed between two grooves 27b in zigzag all around the outer surface 26.

In a third variant illustrated in Figure 6c, the pivot 21 comprises a structure 25 formed of a substantially helical groove 27b on the outer surface 26, first recesses 27a of substantially rectangular sections (extending substantially perpendicularly relative to to the length of the shaft 1) distributed around the turns of the groove 27b all around the outer surface 26 and d second recesses 27a of substantially rectangular sections (extending substantially parallel to the length of the shaft 1) distributed between a turn of the groove 27b and a first recess 27b in order to make them communicate together.

In the fourth variant illustrated in Figure 6d, the pivot 21 comprises a structure 25 formed of a substantially helical groove 27b on the outer surface 26 and recesses 27a of substantially circular sections distributed around the turns of the groove 27b all around the outer surface 26.

Of course, the variants of the third embodiment can be combined and / or each recess 27a can be of different geometry to the others and / or the recesses 27a can be distributed in a different way (different density for the same area, different distribution particularly asymmetric, etc.) on the outer surface 26 of the pivot 21 and / or each groove 27b may be of different geometry to the others and / or the grooves 27b may be distributed in a different manner (different density for the same surface, different distribution, in particular asymmetric , etc.) on the outer surface 26 of the pivot 21.

Whatever the embodiment or the variant of the invention, the maximum dimension of the outline of the pattern 27 on the surface of the pivot 21 measured in a plane perpendicular to the axis of the pivot 21, that is to say - say substantially the width L, is preferably between 300 nm and 1 pm, that is to say, for example, 300 nm, 350 nm, 400 nm, 450 nm, 475 nm, 500 nm, 525 nm, 550 nm , 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm. In addition, the structuring 25 may include a ratio between the width L and the depth between 5 and 20, that is to say if the width L of the structure is equal to 500 nm, the depth of the structuring 25 is preferably between 100 nm and 25 nm. Of course, the dimensions of the width L, the depth and the length of the patterns 27 may be different from these preferred dimensions without departing from the scope of the invention. In no way limiting, the width L could thus be greater than 1 μm without departing from the scope of the invention.

Of course, each embodiment and / or variant can have a percentage coverage of the pivot 21 and / or a structuring density 25 and / or a pattern width L 27 and / or a specific pattern depth 27 ( s) compared to other embodiments and / or variants. It can also be envisaged that the percentage of coverage of the pivot 21 and / or the structuring density 25 and / or the width L and / or the depth of the structuring 25 evolves on the external surface 26 of the pivot 21, for example example, depending on the location on the pivot 21. In no way limiting, it could be envisaged that the structuring 25 decreases in density and / or in width L and / or in depth as the outer surface 26 of the pivot 21 moves away from the oiler 20 of the bearing 9, that is to say both towards the rod 23 and towards the free end of the pivot 21.

In the particular example of an axis A of balance 13, the invention could provide an additional advantage. Indeed, it is constantly sought to minimize the amplitude deviations of the balance 13 (maximum angle of the balance 13 at each alternation) between the horizontal (HH, HB) and vertical (VH, VG, VD, VB) positions of the part. 2 clockwork. Typically, it is generally desired that the friction moments at the two positions (HH, HB, VH, VG, VD, VB) are identical.

The flat friction moment is written: 'Tj'

The hangman friction moment is written:

Vlpendu = MpenduPr (2)

[0043] Where:

p is the friction coefficient of the position;

P is the weight of the oscillator;

r1 is the external radius of the flat friction surface;

r0 is the internal radius of the flat friction surface;

r is the radius of the axis in contact with the hanger pad.

To minimize the differences, it is sought to obtain:

Flat = Mpendu- (3)

This results in the following equality: î— "| 4>

If either a 33% lower coefficient of friction hanging, then the moment of friction hanging will be substantially equivalent to the moment of friction flat. The solution usually implemented is to carry out

Claims (10)

flat on the ends of the pivots 21 to minimize the amplitudes in horizontal positions, that is to say that the horizontal amplitudes are degraded to bring them closer to the vertical amplitude values. Advantageously according to the invention, at least one of the two pivots 21 of the axis A of the balance 13 comprises a structure 25 of its outer surface 26 at the level of the cylindrical base of the pivot 21 which comes into contact with the hole 10 of the pad 9 in order to minimize hanged friction in order to increase the amplitudes at at least one of the vertical positions. Conversely to the solution usually implemented, the structuring 25 according to the invention makes it possible to keep a conical free end of the pivot 21 and therefore offers a gain in friction coefficient allowing the moment of friction on the hanged to be substantially equivalent to flat friction moment without having to degrade the horizontal amplitudes. It is therefore understood that the amplitudes will be identical between the positions (difference between flat and hanged low or zero as previously) but with a greater chronometric performance, in particular by the higher amplitudes obtained whatever the positions. Claims 1. Clockwork shaft (1) for the rotational assembly of at least one member comprising a bearing surface (22) intended to receive the member and a pivot (21) at each of its two free ends intended to pivot in a bearing ( 7) to make the member movable in rotation, characterized in that at least one of the two pivots (21) comprises a structuring (25) of its outer surface (26) in order to minimize its contact surface with the bearing (7) ). 2. Shaft (1) watchmaker according to the preceding claim, wherein the structuring (25) comprises at least one pattern (27, 27a, 27b) recessed on the surface (26) external of the pivot (21). 3. Shaft (1) watchmaker according to the preceding claim, wherein the pattern (27, 27a, 27b) hollow of the structuring (25) has a width (L) between 300 nm and 1 pm. 4. Shaft (1) watchmaker according to claim 2 or 3, wherein the pattern (27, 27a, 27b) hollow of the structure (25) has a ratio between the width (L) and the maximum depth between 5 and 20. 5. Watch tree (1) according to any one of the preceding claims, in which the structuring (25) represents between 5% and 50% of the external surface (26) of the pivot (21). 6. Tree (1) watchmaker according to any preceding claim, wherein the structuring (25) forms at the at least one groove (27b) to form a circulation channel for lubricant on the outer surface (26) of the pivot (21). 7. Tree (1) watchmaker according to any preceding claim, wherein the structuring (25) forms at at least one recess (27a) to form a reservoir for lubricant on the outer surface (26) of the pivot (21). 8. Shaft (1) watchmaker according to any one of the preceding claims, comprising pivot ends (21) conical, a cylindrical base of at least one of the two pivots (21), called contact surface, comprising a structuring ( 25) of its outer surface (26) in order to selectively differentiate the coefficient of friction of the contact surface from that of the tapered end of the pivot (21) of the shaft (1). 9. Watch movement (3) comprising at least one bridge (5) and one plate (6) each provided with bearings (7) and at least one watch shaft (1) assembled between a bearing (7) of the bridge (5) and a bearing (7) of the plate (6) in order to be pivotally mounted, characterized in that the watch shaft (1) is according to one of the preceding claims. 10. Watch movement (3) according to the preceding claim, wherein the watch shaft (1) is an axis (A) of balance (13), a rod (B) of anchor (17), a shaft (C) toothed wheel (18) or a barrel shaft. Fig. 1 Fig. 2 21 23 Vm / 23 24 21 Fig. 3a Fig. 3b Fig. 3c ? 5 21 27a J / 27a 0 0 0 D 0 0 0 0 D D 0 D D D 0 0 0 0 0 D D 0 0 0 0 D D D 0 0 D D D 0 D 0 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O CH7le332Al f'9. 4a o 25 27b V 26 —A ^ x Z Z7 Z7 J J J oonajoij Fi9. Sb 27b S -Oioj s O O O O ) 6 y L J> / 6 q ~ ~ ~ o / 'O O' O / O O O O / 'Q ’O O rp o o o ~ «ô 1 ^ 7 Fig. 7 21 10 23 24 15 ï