HK1235108A1 - Timepiece train - Google Patents

Description

Clock wheel set

Technical Field

The invention relates to a timepiece wheel set (i.e. a timepiece movement device) comprising several parts, wherein the wheel set comprises a first member formed by a spindle comprising a housing cavity about a first pivot axis arranged for receiving a second member formed by a disc (plate) in a single axial position, the disc comprising an outer peripheral surface about a second pivot axis, the spindle comprising, on either side of the at least one housing cavity and in the direction of the first pivot axis, an axial abutment surface arranged to maintain the disc in abutment on the spindle, wherein the disc comprises at least one first arm resilient in the radial direction about the second pivot axis and at least one second arm stiff or resilient in the radial direction about the second pivot axis, the first resilient arm and the second arm together forming a clamping device, the clamping device is arranged to clamp a radial bearing surface comprised in the spindle adjacent to the axial abutment surface, wherein the spindle comprises an entry ramp arranged to push back each of the first resilient arms radially and, in case the disc comprises second resilient arms, also to push back each of the second resilient arms radially to allow placing the disc on the spindle.

The invention also concerns a timepiece movement including at least one wheel set of this type.

The invention relates to the field of horological mechanisms and more specifically gear trains.

Background

Many mechanical timepiece movements include at least one element with a friction fit, in particular in order to allow adjustment during operation of the watch.

For example, a mechanical movement equipped with a centre wheel usually comprises a friction fit in relation to the motion gear train.

This friction allows the gear shaft to rotate independently of the going train when the hands are set. The friction also allows the integral rotation of the driving wheel disc during the operation of the watch.

French patent 1222456 in the name of EBAUCHES ETA AG discloses a wheel and pinion with a disc comprising three substantially radial elastic arms arranged to grip a smooth spindle in a friction fit. More specifically, the ends of the arms have a hollow profile matching the radius of the mandrel.

Us patent 2006/187768 in the name of maraumi discloses a wheel structure comprising a disc resiliently fixed to a spindle.

Japanese patent S59135385 in the name of SEIKO discloses a plastic wheel resiliently fixed to a metal pinion.

Japanese patent S5091562 in the name of SEIKO discloses a wheel with discs having spokes resiliently fixed to a spindle.

Disclosure of Invention

To this end, the invention concerns a timepiece wheel set comprising several parts according to claim 1.

The invention also concerns a timepiece movement including at least one such wheel set, characterized in that the composition of said wheel set is limited to said arbour and said disc being assembled one on top of the other.

Drawings

Other features and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:

figure 1 shows a schematic perspective view of a wheel set according to the invention, comprising a disc friction-fitted on a spindle.

Figure 2 shows a schematic view of the wheel set of figure 1 in section through the pivot axis.

Figure 3 shows a schematic top view of the wheel set of figure 1.

Figure 4 shows a schematic perspective view of the spindle comprised in the wheel set of figure 1.

Figure 5 shows a schematic view of the spindle of figure 4 in a section through the pivot axis.

Figure 6 is a detail view of the assembly area of figure 2.

Fig. 7 shows a schematic top view of the disc comprised in the wheel set of fig. 1, in an embodiment of the "two-contact-point" type.

FIG. 8 is a side view of the disc of FIG. 7.

FIG. 9 is a detailed top view of the central area of the disk of FIG. 7.

Fig. 10 shows a schematic view similar to fig. 7 of another embodiment with four contact points.

Fig. 11 shows, in a similar manner to fig. 10, a further embodiment with four contact points, which are arranged at an angle of substantially 90 ° to each other.

Figure 12 is a side view of the wheel set of figure 11.

Figure 13 is a partial section view of the wheel set of figure 11, in a plane passing through the pivot axis, with a profile different from that of figure 6.

Detailed Description

The invention concerns a timepiece wheel set 100 comprising several parts.

More specifically, the wheel set includes a friction device and is referred to as a "friction wheel set".

According to the invention, wheel set 100 comprises a first component formed by spindle 1. The spindle 1 comprises a housing cavity 6 about the first pivot axis D1, which housing cavity 6 is arranged for receiving a second component. The second member is formed by the disc 2 in a single axial position.

The disk 2 includes an outer peripheral surface 20 about the second pivot axis D2.

On both sides of said at least one housing cavity 6 and in the direction of the first pivot axis D1, the spindle 1 comprises axial abutment surfaces 7, said axial abutment surfaces 7 being arranged to hold the disk 2 in abutment on the spindle 1.

The disc 2 comprises at least one first arm 4 which is resilient in the radial direction about the second pivot axis D2 and at least one second arm 5 which is stiff or resilient in the radial direction about the second pivot axis D2.

The first resilient arm 4 and the second arm 5 together form a gripping means 3, which gripping means 3 is arranged to grip a radial bearing surface 9 comprised in the spindle 1 in the immediate vicinity of the axial abutment surface 7. Thus ensuring friction between the disc 2 and the spindle 1.

For fitting the disc 2 on the spindle 1, the elasticity of the arms 4, 5 of the disc 2 is utilized to achieve correct positioning and preferably snapping into place.

According to the invention, the spindle 1 comprises an entry ramp 8, which entry ramp 8 is arranged to push back radially each first elastic arm 4 and, if included in the disc 2, each second elastic arm 5, to allow the disc 2 to be placed on the spindle 1.

In a particular embodiment, the disk 2 comprises a first elastic arm 4 and a second elastic arm 5 symmetrical to each other about the second pivot axis D2.

Advantageously, in the free state, the gripping device 3 circumscribes a cylinder with a smaller radius than the cylinder circumscribing the radial bearing surface 9.

The central part of the disc 2 comprises as many curved surfaces as there are arms 4, 5, in particular a substantially cylindrical surface. In the variant shown in the figures, comprising a first elastic arm 4 and a second arm 5, the centre of the disk is defined by two curved surfaces that grip the spindle 1.

Fig. 7 shows an embodiment of the "two-point" type, in which the disk 2 rests on the spindle 1 at two symmetrical points P1 and P2 with respect to the axis D1. Each first arm 4 or second arm 5 thus comprises one such curved surface formed by a substantially cylindrical section 34, 35, in particular with a hollow oval cross-section, the axis C of which is eccentric with respect to the second pivot axis D2.

Preferably, as can be seen in fig. 9, the axis C is therefore offset from the substantially cylindrical hollow section 34, 35 by a value E which is between 0.1 and 0.2 times the radius of the relevant substantially cylindrical hollow section 34, 35, more than the second pivot axis D2.

For the friction of the motion gear, the friction value is advantageously defined by a precise range of 0.060 to 0.080n.cm to meet the quality standards set for anti-seismic performance and hands.

It will be appreciated that friction may be achieved on a surface of a certain size (such as the generally cylindrical sections 34, 35) or at a particular point (e.g. in the form of a two or four point friction).

An embodiment of the "four dots" type can be seen in fig. 10: the disk 2 rests on the spindle 1 at four points P11, P12, P13, P14, which are symmetrical in pairs about the axis D1. The inner radius Rp of the disk is thus smaller than the tooth axis radius Rch on the spindle 1. For the variant of fig. 11, the four points are designated P21, P22, P23, P24.

In a particular variant, the disc 2 comprises first actuating means 21 on the first elastic arms 4 and second actuating means 22 on each of said second elastic arms 5 (if the disc 2 comprises such second elastic arms). These first 21 and second 22 driving means comprise sections with convex or concave relief profiles arranged to cooperate with tools with complementary profiles when the disc 2 is placed on the spindle 1 to open the clamping means 3.

More particularly, the first drive means 21 and the second drive means 22 are symmetrical with respect to the second pivot axis D2.

In a variant, near the periphery of the disk 2 and in the interior of the disk 2, the disk 2 may also comprise a third drive 23 and a fourth drive 24.

Advantageously, the disc 2 comprises, in its most rigid part, retaining means arranged to cooperate with the drawing tool, such as lugs or perforations or the like.

In one particular variant, disc 2 has a surface roughness greater than 6.3 microns Ra on its lower surface 21 and/or upper surface 22 for friction fit with a holding and/or pulling tool.

In one non-limiting variation, the outer peripheral surface 20 is a ring gear centered on the second pivot axis D2.

In another variant, the outer peripheral surface 20 is a cam with respect to the second pivot axis D2 and the angular reference formed by the first arm 4 or the second arm 5.

In an advantageous embodiment, the radial bearing surface 9 of the spindle 1 and the entry ramp 8 together define a flange 10, which flange 10 is arranged to immobilize the disk 2 on the spindle 1 when the disk abuts against the axial abutment surface 7 of the spindle 1.

In a particular variant, the radial bearing surface 9 has a clearance angle with respect to the flange 10. This clearance angle allows the disc 2 to be maintained at a constant height and a constant friction radius.

The embodiments shown in fig. 11 to 13 are particularly advantageous: it is an embodiment with four contact points P21, P22, P23, P24 arranged at an angle of substantially 90 ° to each other. As shown in fig. 13, the joint between the disc and the spindle has a profile different from that of fig. 6.

The radial bearing surface 9 of the spindle 1 has a clearance angle below the flange that is a small angle "b" comprised between 2 ° and 8 °, preferably close to 5 °. The lower surface of the disc 2 forms an axial abutment surface 7 and abuts on a radial surface 11 of the spindle orthogonal to the axis D1 of said spindle on an annular surface delimited by the inner circle PB and the outer circle PC. The disks are reliably maintained in abutment due to their elasticity and the clearance angle; the disk is in contact with a surface on the tapered cone 9 of the spindle 1 that tapers to a substantially circle at PA. The projection of the circle PA on the radial abutment surface 11 parallel to the axis D1 of the spindle 1 is located between the inner circle PB and the outer circle PC and may coincide with the inner circle PB as shown in fig. 13.

This provides excellent retention and the annular shoulder does not require a large diameter difference, in practice the difference between diameter PC and diameter PB may be less than 10% of the value of diameter PA. The abutment diameter PA can thus be considerably increased in a very advantageous manner compared to the known embodiment of the wheel set with the flange clamped on the spindle.

In this variant, the large-volume lubrication chamber CH is advantageously arranged to recede from the tapered cone 9 at a significantly greater angle (for example 30 ° to 45 °) so as to maximize the volume of the chamber CH delimited on the opposite side by the radial surface 11; the bottom of the chamber CH (close to the axis D1) is determined by calculating the resistance/strength of the material of the spindle 1 from the operating stresses of the wheel set 100.

This depression (staking) means that the chamber CH is a lubrication reservoir that remains sealed with respect to the ring gear 20.

In a particular embodiment, the disk 2 is made of CuBe2 with a thickness close to 0.12mm, the ring gear 20 has a pitch circle diameter close to 4.5mm to receive the spindle 1 with a diameter close to 1.33mm at the bearing circle PA, and the elastic arms 4 and 5 of the disk have a cross section close to 0.3mm in the plane of the disk and a larger spacing of about 1.28mm in the free state before fitting on the spindle, thus a clamping diameter on the spindle of between 0.04mm and 0.05 mm. The hollow sections 34, 35 of substantially elliptical cross-section, between P21 and P22 on the one hand and P23 and P24 on the other hand, which serve to enclose the spindle 1, each have an eccentricity of about 0.2mm in the free state.

In a more particular embodiment, the ring gear 20 has an elliptical profile in the free state to accommodate the deformation of the disk 2, and has an eccentricity similar to that of the shoulders P21-P22 and P23-P24. The ring gear 20 is symmetrical about a plane of symmetry passing through the axis.

This arrangement allows the elasticity of the disk 2 to be utilized to a small extent when the disk 2 is clamped on the spindle 1, and the deformation remains limited to the elastic range, which prevents the formation of burrs. The friction values are only impaired with a very low dispersion.

The invention also concerns a timepiece movement 200 including at least one such wheel set 100. Preferably, the composition of wheel set 100 is limited to spindle 1 and disk 2 assembled on top of each other.

Claims (17)

1. Timepiece wheel set (100) comprising several parts, wherein the wheel set (100) comprises a first member formed by a spindle (1), the spindle (1) comprising a housing cavity (6) about a first pivot axis (D1) arranged for receiving a second member formed by a disc (2) in a single axial position, the disc (2) comprising an outer peripheral face (20) with respect to a second pivot axis (D2), the spindle (1) comprising, on both sides of the at least one housing cavity (6) and in the direction of the first pivot axis (D1), an axial abutment surface (7) arranged to keep the disc (2) in abutment on the spindle (1), wherein the disc comprises at least one first arm (4) resilient in a radial direction with respect to the second pivot axis (D2), and at least one second arm (5) stiff or resilient in a radial direction with respect to the second pivot axis (D2), said first (4) and second (5) arms together forming a gripping device (3) arranged to grip a radial bearing surface (9) comprised in said spindle (1) adjacent to said axial abutment surface (7), wherein said spindle (1) comprises an entry ramp (8) arranged to push back each first elastic arm (4) radially and, in the case of a disc (2) comprising a second elastic arm (5), each second elastic arm (5) radially, to allow the disc (2) to be placed on said spindle (1), said timepiece wheel set being characterized in that said segment axis (C) is distanced from said substantially cylindrical hollow section (34; 35) by an offset value (E) comprised between 0.1 and 0.2 times the radius of said substantially cylindrical hollow section (34; 35) compared to said second pivot axis (D2); -said radial bearing surface (9) of said spindle (1) and said entry ramp (8) together defining a flange (10), said flange (10) being arranged to immobilize said disc (2) on said spindle (1) when said disc abuts on said axial abutment surface (7) of said spindle (1); the radial bearing surface (9) has a clearance angle with respect to the flange (10); and the disk (2) rests on the spindle (1) at four points (P11, P12, P13, P14; P21, P22, P23, P24) which are symmetrical in pairs about the first pivot axis (D1).

2. Wheel set (100) according to claim 1, characterized in that the disk (2) comprises two symmetrical surfaces about the first pivot axis (D1), comprising a disk inner radius (Rp) smaller than a cannon-pinion radius (Rch) comprised in two shoulders of the spindle (1), symmetrical about the first pivot axis (D1) and opposite to the two surfaces of the disk (2).

3. Wheel set (100) according to claim 1 or 2, characterized in that in the free state the radius of the cylinder circumscribed by the gripping device (3) is smaller than the radius of the cylinder circumscribed by the radial bearing surface (9).

4. Wheel set (1) according to any one of claims 1 to 3, characterized in that each first arm (4) or second arm (5) comprises a substantially cylindrical hollow section (35; 35) whose axis (C) is eccentric with respect to the second pivot axis (D2).

5. Wheel set (100) according to claim 4, characterized in that said axis (C) is further from said substantially cylindrical hollow section (34; 35) than said second pivot axis (D2) by a deviation value (E) comprised between 0.1 and 0.2 times the radius of said substantially cylindrical hollow section (34; 35).

6. Wheel set (100) according to any one of claims 1 to 5, characterized in that the disc (2) comprises first drive means (21) on the first elastic arms (4) and, in the case where the disc (2) comprises second elastic arms, the disc (2) also comprises second drive means (22) on each of the second elastic arms (5); and the first drive means (21) and the second drive means (22) comprise sections with convex and/or concave-convex profiles, arranged to cooperate with tools with complementary profiles in order to open the clamping means (3) when the disc (2) is placed on the spindle (1).

7. Wheel set (100) according to claim 6, characterized in that the first drive means (21) and the second drive means (22) are symmetrical with respect to the second pivot axis (D2).

8. Wheel set (100) according to claim 7, characterized in that the disc (2) comprises, in the most rigid part, retaining means for cooperation with a drawing tool.

9. Wheel set (100) according to any one of claims 1 to 8, characterized in that the disc (2) comprises, adjacent to the periphery of the disc (2) and in the interior of the disc (2), a third drive means (23) and a fourth drive means (24).

10. Wheel set (100) according to any one of claims 1 to 9, characterized in that the disc (2) has a surface roughness greater than 6.3 microns Ra on the lower surface (21) and/or on the upper surface (22) in order to be frictionally engaged by a holding and/or drawing tool.

11. The wheel set (100) according to any of claims 1 to 10, characterized in that the outer peripheral surface (20) is a ring gear centered on the second pivot axis (D2).

12. The wheel set (100) according to any of claims 1 to 11, wherein the peripheral surface (20) is a cam with respect to the second pivot axis (D2) and to an angular reference formed by the first arm (4) or the second arm (5).

13. The wheel set (100) according to any of claims 1 to 12, characterized in that the radial bearing surface (9) of the spindle (1) and the entry ramp (8) together define a flange (10) arranged to immobilize the disc (2) on the spindle (1) when the disc abuts on the axial abutment surface (7) of the spindle (1).

14. The wheel set (100) according to claim 13, characterized in that the radial bearing surface (9) has a clearance angle with respect to the flange (10).

15. The wheel set (100) according to any of claims 1 to 14, wherein the four points (P11, P12, P13, P14; P21, P22, P23, P24) are arranged at an angle of substantially 90 ° with respect to each other.

16. The wheel set (100) according to any of claims 1 to 14, characterized in that the spindle (1) comprises a radial bearing surface (9) for receiving the disk (2), having a clearance angle below the flange (10), i.e. a small angle (b) comprised between 2 ° and 8 °; the disc (2) comprises a lower surface forming an axial abutment surface (7) which abuts, on an annular surface delimited by an inner circle (PB) and an outer circle (PC), a radial surface (11) of the spindle (1) orthogonal to the axis (D1) of the spindle (1), the disc (2) being in contact with the spindle (1) on a surface of the radial support surface (9) substantially reduced to a circle (PA) when in an assembled position on the spindle (1), the projection of the circle (PA) on the radial support surface (11) parallel to the axis (D1) of the spindle (1) being located between the inner circle (PB) and the outer circle (PC) and coinciding with the inner circle (PB).

17. A timepiece movement (200) including at least one wheel set (100) according to any one of claims 1 to 16, characterised in that the composition of the wheel set (100) is limited to the spindle (1) and the disc (2) being assembled one on top of the other.