EP2802943B1 - Clockwork with tilted balances - Google Patents

Description

The present invention relates to a mechanical clockwork movement for a timepiece such as a wristwatch.

In a mechanical clockwork movement, the regulating member which measures the time and imposes a clocked movement on the various mobiles generally comprises a rocker secured to a shaft on which is also mounted a spiral via a ferrule, and an escapement to maintain oscillations of the pendulum. The accuracy of the movement depends on the regularity of the pendulum oscillations. One of the most influential parameters on the regularity of the oscillations is the position of the watch. The oscillation amplitude of the pendulum of a clock oriented in a horizontal plane is typically about 320 °. This amplitude can decrease by about 40 ° when the watch is oriented vertically, due to the fact that the friction of the pivots of the balance shaft in their bearings become larger. In addition, since the center of gravity of a conventional flat hairspring is not on the axis of the balance-spring, and moves even during expansions and contractions of the hairspring, an unbalance is generated in a vertical position, which will create either an advance or a delay, this is called the Grossmann effect. Thus, the walking of the watch also varies between the different vertical positions. In a given vertical position of the watch, the oscillations of the pendulum will produce a delay if the center of gravity of the spiral is above the axis of balance and the advance if this center of gravity is below the balance shaft.

It is possible to choose the angular position of the point of attachment of the hairspring to the shell so that, in a predetermined vertical position of the watch, typically the position considered to be the most common, a march advance due to the decentering of the center of gravity of the hairspring compensates for a delay in operation due to the vertical position relative to the horizontal position, minimizing thus the influence of gravity in this predetermined position. This solution has only a limited effect because it does not solve the problem for the other vertical positions of the watch. An alternative is to use a Breguet hairspring, that is to say a hairspring having an outer curve coming out of the plane of the hairspring and shaped so that the center of gravity of the hairspring remains on the axis of the balance. But this type of hairspring is quite difficult to put in place. In addition, it does not solve the problem of the gap between the horizontal and vertical positions.

To increase the precision of a mechanical clockwork movement, it is also known to equip the movement with two rockers and a differential gear arranged to average the steps of the rockers, as described in the patent CH 156801 . Such a solution reduces the deviation due to gravity, but in a rather limited way.

Another solution has been proposed in the patent application WO 2011/058157 , consisting in equipping the movement with inclined pendulums and differential gears, the rockers being arranged to define a regular polyhedron. Two examples of embodiments are described in this document WO 2011/058157 and illustrated by his figures 1 and 2 respectively. In the first example, four sets each comprising a barrel, a work train and a rocker are oriented so that planes perpendicular to the pivot axes of the rockers define a regular tetrahedron. The axes of the balances are thus between them an angle of about 70 °, corresponding to the dihedral angle of the regular tetrahedron. In the second example, three sets each comprising a barrel, a work train and a rocker are oriented so that planes perpendicular to the pivot axes of the rockers define the three sides, in the form of isosceles right triangles, of a pyramid equilateral triangular basis. According to this document WO 2011/058157 , this pyramid forms part of a cube of which three of the faces are formed of a square obtained by the addition of a second right triangle adjacent to the three right triangles. This is not possible because angles that make between them the axes of the pendulums on the figure 2 are all different from 90 °, which is incompatible with a cubic arrangement. It should also be noted that this document WO 2011/058157 it remains in the form of schematic diagrams and gives no example of a construction which concretely makes it possible to carry out the movement described.

Finally, the tourbillon mechanisms are another known solution for improving the running accuracy of a movement. These mechanisms, however, have the disadvantage of being complicated and expensive to implement. Moreover, their effect is limited to averaging the steps in the different vertical positions of the watch, without answering the problem of the difference between the horizontal and vertical positions.

The present invention aims to remedy, at least in part, the aforementioned drawbacks and to propose an alternative approach to compensate for the effects of gravity on the progress of a movement. For this purpose, there is provided a watch movement according to the appended claim 1, particular embodiments being defined in the dependent claims.

• la figure 1 est une vue plane, prise depuis le côté cadran, d'un mouvement selon l'invention ;
• la figure 2 est une vue plane simplifiée du mouvement selon l'invention, montrant les points d'attache de spiraux à des viroles ;
• la figure 3 est une vue de côté montrant un décalage en hauteur entre deux organes régulateurs équipant le mouvement selon l'invention ;
• la figure 4 est une vue en coupe selon l'axe 3 heures - 9 heures d'une partie du mouvement selon l'invention ;
• la figure 5 est une vue en coupe, prise suivant une ligne brisée, du mouvement selon l'invention ;
• la figure 6 est une vue en perspective, prise depuis le côté fond, d'une partie du mouvement selon l'invention ;
• la figure 7 est une vue en perspective d'une partie d'un pont de rouage du mouvement selon l'invention ;
• la figure 8 montre des graphes représentant l'amplitude d'oscillation de balanciers du mouvement selon l'invention en fonction de la position dudit mouvement ; et
• la figure 9 montre des graphes représentant l'écart de marche dû à l'effet Grossmann des balanciers du mouvement selon l'invention en fonction de la position dudit mouvement.

Other features and advantages of the present invention will appear on reading the following detailed description given with reference to the appended diagrammatic drawings, in which:

• the figure 1 is a plan view, taken from the dial side, of a movement according to the invention;
• the figure 2 is a simplified plan view of the movement according to the invention, showing the points of attachment of spirals to ferrules;
• the figure 3 is a side view showing an offset in height between two regulating members equipping the movement according to the invention;
• the figure 4 is a sectional view along the axis 3 hours - 9 hours of a part of the movement according to the invention;
• the figure 5 is a sectional view, taken along a broken line, of the movement according to the invention;
• the figure 6 is a perspective view, taken from the bottom side, of a part of the movement according to the invention;
• the figure 7 is a perspective view of a portion of a gear wheel of the invention;
• the figure 8 shows graphs representing the oscillation amplitude of the rockers of the movement according to the invention as a function of the position of said movement; and
• the figure 9 shows graphs representing the walking gap due to the Grossmann effect of the rockers of the movement according to the invention as a function of the position of said movement.

With reference to Figures 1 to 7 , a watch movement according to a preferred embodiment of the invention comprises, mounted in a frame, a mobile center 1, two barrels 2a, 2b located on either side of the mobile center 1, two mobile of mean 3a, 3b located on either side of the center mobile 1, four second mobiles 4a, 4b, 4c, 4d and four regulating members 5a, 5b, 5c, 5d. The frame comprises a plate 6 and bridges, in particular a first axle 7a receiving pivots of the shafts of the mobile of average 3a and second mobiles 4a, 4b, a second axle 7b receiving pivots of the shafts of the mobile of mean 3b and second movers 4c, 4d, a center bridge 7 'and two barrel bridges 7 ", 7'''. Each regulating member 5a to 5d comprises an escapement 8a to 8d, a balance 9a to 9d and a spiral 10a to 10d, the spiral being mounted on the same shaft as the balance by a ferrule 11a to 11d (cf. figure 2 ), in the usual way. Each exhaust 8a to 8d typically comprises an escape wheel, comprising a wheel and an escape pinion, an anchor and a double plate mounted on the balance shaft. Differentials, which will be described later, allow the display members of the movement (not shown) to display a time corresponding to the average of the times measured by the four regulating members 5a to 5d, thus conferring on the movement a high precision of market.

Each regulating member 5a to 5d is disposed in a plane inclined at 45 ° relative to the plane of the plate 6 or, which amounts to the same, of the movement. In other words, the axis 12a to 12d of each balance 9a to 9d, that is to say the imaginary axis around which each balance oscillates, forms an angle of 45 ° with the plane of the plate 6 or movement. In top view of the movement ( figure 1 ), the pendulums 9a to 9d form the ends of a cross whose center is at the center of the movement and whose two branches are perpendicular. The rockers diametrically opposed to each other 9a, 9c have their axes 12a, 12c which intersect the axis 13 of the movement in one and the same point 14. The two other rockers opposite each other 9b, 9d have their axes 12b, 12d which intersect the axis 13 of the movement at the same point 15 which is typically on the same side of the plate 6 as the point 14 but distinct from the latter because the regulating members 5a, 5c are at a position raised by compared to the regulatory bodies 5b, 5d, as shown in figures 3 and 5 in order to allow the second wheels of the second wheels 4a, 4b and the second wheels of the second wheels 4c, 4d to overlap (cf. figure 1 ).

In this way, the angle between them the axes 12a, 12c of the pendulums 9a, 9c is 90 °. Similarly, the angle between them the axes 12b, 12d of the pendulums 9b, 9d is 90 °. In addition, the axes 12a, 12c of the pair of pendulums 9a, 9c are not parallel to any of the axes 12b, 12d of the other pair of pendulums 9b, 9d, thus providing coverage of all directions of the space. The orthogonality between the axes of the rockers of the same pair 9a, 9c or 9b, 9d makes it possible to effectively compensate the effects of gravity on these rockers and to particularly well cover the possible positions of the movement between the horizontal and the vertical ( flat-hung). Thanks to this orthogonality, the average of the oscillation amplitudes of the rockers of a given pair remains substantially constant between the different angular positions of the movement in the diametral plane containing the axes of these rockers.

As an illustration, the table below indicates the amplitude of oscillation (in degrees) of each pendulum for five different positions of the movement, namely:
a first position P1 where the movement is in a horizontal plane and the rockers are thus inclined by 45 ° with respect to this horizontal plane,
a second position P2 where the movement is inclined at 45 ° with respect to a horizontal plane, the balance 9a is horizontal and the opposite balance 9c is vertical,
a third position P3 where the movement is inclined at 45 ° with respect to a horizontal plane, the balance 9b is horizontal and the opposite balance 9d is vertical,
a fourth position P4 where the movement is inclined at 45 ° with respect to a horizontal plane, the balance 9c is horizontal and the opposite balance 9a is vertical,
- And a fifth position P5 where the movement is inclined by 45 ° relative to a horizontal plane, the balance 9d is horizontal and the opposite balance 9b is vertical. P1 P2 P3 P4 P5 9a pendulum 300 320 300 280 300 Balance 9b 300 300 320 300 280 9c pendulum 300 280 300 320 300 9d pendulum 300 300 280 300 320 Average 300 300 300 300 300

The positions P2 to P5 are extreme positions of the movement in that they are the positions in which the gait differences between the rockers due to the differences in friction of the balance pins in their Bearings are the largest. As can be seen, the average of the oscillation amplitudes of the rockers in the positions P1 to P5 is the same, namely 300 °. The figure 8 shows graphs Ga to Gd representing the oscillation amplitude of the pendulums 9a to 9d, respectively, as a function of the position of the movement. It can be seen that the opposite rockers of the same pair have their oscillation amplitudes which compensate each other and that the average of the oscillation amplitudes remains the same whatever the position of the movement, this average corresponding to the amplitude of the oscillation amplitude. oscillation of the rockers when the movement is horizontal. The operating deviations between the horizontal position and the non-horizontal positions of the movement are thus significantly reduced. This effect is obtained thanks to the orthogonality between the axes of the balances of the same pair which makes that, in the extreme positions of the movement, one of the pendulums is horizontal while its opposite pendulum is vertical. Another advantage of the orthogonality between the axes of the rockers of the same pair is that the average step of the rockers is less sensitive to the walking errors of each of the rockers. Indeed, as the average is performed between values that are distant from each other, a difference in the operation of a balance relative to its theoretical step (due for example to an inaccuracy of adjustment) will have less influence than with pendulums making a different angle of 90 ° between them.

The angle of 90 ° between the axes of the rockers of the same pair could be obtained with an inclination of the rockers relative to the plate different from 45 °. For example, one of the rockers could be flat and the other perpendicular to the plate, or one could be at 30 ° and the other at 60 ° relative to the plate. The inclination of 45 ° is however preferred because, thus, the balance 9a to 9d are never in their most unfavorable position in terms of sensitivity to gravity, namely the vertical position, when the movement is in one of its reference positions, namely the horizontal "dial at the top" and "dial at the bottom" and vertical "3 hours at the top", "6 o'clock at the top", "9 hours up "and" 12 hours up ". The difference in path between the reference positions of the movement is therefore small.

According to another advantageous characteristic of the present invention, the attachment points 16a to 16d of the spirals 10a to 10d to the rings 11a to 11d are positioned in such a way that the deviations due to the decentering and the displacement of the center of gravity of the spirals (Grossmann effect) counterbalance each other. The figure 2 shows in schematic top view the balance 9a to 9d, the rings 11a to 11d and the beginning of the inner curve of the spirals 10a to 10d. For simplicity, the rockers 9a to 9d are shown flat on the plate 6. As can be seen, the attachment points 16a to 16d of the spirals to the ferrules are offset relative to each other. More specifically, the angular position of the attachment point 16a, measured in a reference whose center is on the axis 12a of the balance 9a, is offset by 180 ° relative to the angular position of the attachment point 16c, measured in a same reference but whose center is on the axis 12c of the balance 9c. The angular position of the attachment point 16b, measured in a coordinate system whose center is on the axis 12b of the balance 9b, is offset by 180 ° with respect to the angular position of the attachment point 16d, measured in the same reference but whose center is on the axis of the balance 9d. In addition, the angular positions of the attachment points are offset by 90 ° between each balance of a pair 9a, 9c or 9b, 9d and each balance of the other pair 9b, 9d or 9a, 9c.

As an illustration, the table below shows the deviation (in seconds / day) of each pendulum due to the Grossmann effect for five different positions of the movement, namely:
a first position P1 'where the movement is in a horizontal plane (in this position, the Grossmann effect does not occur),
a second position P2 'where the movement is in a vertical plane and the balances 9a and 9b are at the top (cf. figure 2 )
a third position P3 'where the movement is in a vertical plane and the pendulums 9d and 9a are at the top,
a fourth position P4 'where the movement is in a vertical plane and the pendulums 9c and 9d are at the top,
and a fifth position P5 'where the movement is in a vertical plane and the pendulums 9b and 9c are at the top. P1 ' P2 ' P3 ' P4 ' P5 ' 9a pendulum 0 5 0 -5 0 Balance 9b 0 0 -5 0 5 9c pendulum 0 -5 0 5 0 9d pendulum 0 0 5 0 -5 Average 0 0 0 0 0

The positions P2 'to P5' are extreme positions of the movement in that they are the positions in which the gimbals between the pendulums due to the Grossmann effect are the greatest. As can be seen, the average of the gimbals in the positions P1 'to P5' is 0 seconds / day. The figure 9 shows graphs Ga 'to Gd' representing the deviation due to the Grossmann effect of the pendulums 9a to 9d, respectively, as a function of the position of the movement. It can be seen that the opposing pendulums of the same pair have their differences of course which compensate each other and that the average of the differences of march remains null whatever is the position of the movement. The differences between the different vertical positions of the movement are therefore significantly reduced.

The movement according to the present invention thus makes it possible to greatly reduce both the variations in the path between the horizontal and vertical positions (due to differences in the friction of the balance pins in their bearings) and the variations in the path between the different vertical positions (due the decentering and the displacement of the centers of gravity of the spirals).

The structure of the movement according to the invention will now be described in more detail.

As shown in figures 4 and 5 , the center mobile 1 comprises, around a center shaft 20, a roadway 21 frictionally mounted on the shaft 20 and carrying a minute hand (not shown), an hour wheel 22 free to rotate around the shaft 20 and carrying an hour hand (not shown), a differential gear 23 and a center pinion 24 integral with the shaft 20. The center pinion 24 meshes with the two barrels 2a, 2b (whose associated ratchets n have not been shown) which, thus arranged in parallel, add their torques to drive the center shaft 20. The hour wheel 22 and the roadway 21 mesh respectively with the pinion and the wheel of a timer wheel 25 ( cf. figure 1 ). The timer wheel is connected to the time-setting rod 26 by a time-setting train 27. The differential gear 23 comprises, in addition to the shaft 20 which constitutes it. input, a first output wheel 28 free in rotation relative to the shaft 20, a pinion 29 integral with the wheel 28, a second output wheel 30 free to rotate relative to the shaft 20, a central gear 31 integral with the shaft 20, and a satellite mobile comprising a pinion 32 which meshes with the central pinion 31 and a wheel 33 which is integral with the pinion 32 and which meshes with the pinion 29, the pivots of this satellite mobile being respectively mounted in the second output wheel 30 and in a bridge 34 fixed to the wheel 30.

The two average mobiles 3a, 3b each comprise, around an average shaft 35a, 35b, a pinion of average 36a, 36b integral with the shaft 35a, 35b and a differential gear 37a, 37b. The average gear 36a meshes with, and is driven by, the first output gear 28 of the differential gear 23 and the average gear 36b meshes with, and is driven by, the second output gear 30 of the differential gear 23. The differential gear 37a, 37b of each mobile of average 3a, 3b is of the same type as the differential gearing 23 of the center mobile 1. The average shaft 35a, 35b constitutes entry. One, 38a, of the output wheels of the differential gear 37a meshes with, and drives, a pinion (not shown) of the second wheel 4a, while the other wheel 39a meshes with, and drives, a pinion 40b of the mobile of the second 4b. Similarly, one, 38b, of the output wheels of the differential gear 37b meshes with, and drives, a pinion 40c of the second gear 4c, while the other output gear 39b meshes with, and drives, a pinion (not shown) of the mobile of the second 4d. The wheels of the second movable 4a to 4d meshing by means of bevel gears with the exhaust gears of the regulating members 5a to 5d.

As they are arranged, on the mobiles of center 1 and average 3a, 3b, the differential gears 23, 37a, 37b are closer to the barrels 2a, 2b, that is to say where the torque is Most important. This arrangement compensates for the disadvantages of a differential gear that are its weight and inertia.

The structure as described above has the advantage of a small footprint because the four regulating members 5a to 5d are driven by the same motor member, constituted by the two barrels 2a, 2b, and a single mobile. average is used for two regulating bodies. The use of two barrels in parallel makes it possible to increase the torque necessary for driving the regulating members. It also allows, by the arrangement of these barrels 2a, 2b on either side of the mobile center 1, to balance the transmitted torque and to reduce the air pressure on the pivots of the mobile center 1. Alternatively, , drive members connected by the differentials could separate separately the regulating members 5a to 5d. In another variant, a single barrel could be used to drive the four regulating members 5a to 5d.

Each regulating member 5a to 5d is mounted in a frame 41 (cf. figures 3 and 6 ) comprising an exhaust door 42, an exhaust bridge 43 and a rocker bridge 44 fixed to the exhaust door 42. The pivots of the balance shaft rotate in bearings 45, 46 (cf. figures 3 and 5 ), preferably anti-shock, respectively equipping the exhaust door 42 and the rocker bridge 44. The escape wheel and the anchor are mounted between the exhaust port 42 and the exhaust bridge 43. The frames 41 of the organs regulators 5a to 5d are fixed to the frame of the movement, for example by means of screws, against bearing surfaces 47 of the axles 7a, 7b which are inclined by 45 ° so as to obtain the inclination of 45 ° of the rockers 9a to 9d relative to the plate 6, while allowing said platen to remain flat. These inclined surfaces 47 are represented at figure 7 and, schematically, at the figure 5 . In the exemplary embodiment shown, the frames 41 of the regulating members 5a, 5b are fixed on the first gearbridge 7a, while the frames 41 of the regulating members 5c, 5d are fixed on the second gearbridge 7b.

Although the embodiment of the invention described above and illustrated in the drawings is the preferred embodiment, modifications could be made without departing from the scope of the appended claims. For example, a single pair of pendulums could be provided instead of two. Conversely, the movement could include more than two pairs of pendulums. The axes of the balances of the same pair could not be secant, that is to say, not be in the same plane, as long as they remain orthogonal. By "orthogonal" is meant that said axes form a right angle, if they are in the same plane, or that a straight line parallel to one of these axes crosses the other axis at a right angle, if these axes are not in the same plane.

Claims (14)

1. Timepiece movement comprising driving means (2a, 2b), first, second and third regulating members (5a, 5c, 5b) each comprising a balance (9a, 9c, 9b), and linking means (1, 3a, 3b, 4a-4d) linking the driving means to the regulating members, the axes (12a, 12c) of the balances of the first and second regulating members (5a, 5c) being substantially orthogonal to each other, characterised in that it further comprises a fourth regulating member (5d) comprising a balance (9d) and linked to the driving means (2a, 2b) by the linking means (1, 3a, 3b, 4a-4d), and in that the axes (12b, 12d) of the balances (9b, 9d) of the third and fourth regulating members (5b, 5d) are substantially orthogonal to each other and non-parallel to the axes (12a, 12c) of the balances (9a, 9c) of the first and second regulating members (5a, 5c).
2. Movement according to claim 1, characterised in that the axes (12a, 12c) of the balances (9a, 9c) of the first and second regulating members (5a, 5c) are substantially secant.
3. Movement according to claim 1 or 2, characterised in that the axes (12b, 12d) of the balances (9b, 9d) of the third and fourth regulating members (5b, 5d) are substantially secant.
4. Movement according to any of claims 1 to 3, characterised in that the balances (9a-9d) of the first to fourth regulating members (5a-5d) are arranged, in top view of the movement, so as to form the ends of a cross.
5. Movement according to any of claims 1 to 4, characterised in that the linking means (1, 3a, 3b, 4a-4d) comprise a centre mobile (1) arranged to be driven by the driving means (2a, 2b), first and second third mobiles (3a, 3b) arranged to be driven by the centre mobile (1), first and second fourth mobiles (4a, 4b) arranged to be driven by the first third mobile (3a) and third and fourth fourth mobiles (4c, 4d) arranged to be driven by the second third mobile (3b), the first to fourth fourth mobiles (4a-4d) being arranged to drive the first to fourth regulating members (5a-5d) respectively.
6. Movement according to claim 5, characterised in that the centre mobile (1) comprises a first differential gearing (23) and the first and second third mobiles (3a, 3b) comprise second and third differential gearings (37a, 37b) respectively to average the runnings of the first to fourth regulating members (5a-5d).
7. Movement according to any of claims 1 to 5, characterised in that the linking means (1, 3a, 3b, 4a-4d) comprise at least one differential (23, 37a, 37b) to average the runnings of the regulating members (5a-5d).
8. Movement according to any of claims 1 to 7, characterised in that each regulating member (5a-5d) further comprises a balance-spring (10a-10d) fastened by a collet (11a-11d) to a shaft on which the balance (9a-9d) is mounted, and in that the points (16a-16d) of junction of the balance-springs to the collets are angularly shifted relative to each other so that the running deviations of the balances caused by the Grossmann effect mutually compensate.
9. Movement according to any of claims 1 to 8, characterised in that each balance (9a-9d) is inclined relative to the plane of the movement.
10. Movement according to claim 9, characterised in that each balance (9a-9d) is inclined by about 45° relative to the plane of the movement.
11. Movement according to claim 9 or 10, characterised in that each regulating member (5a-5d) is mounted in a frame (41) fastened against one or more inclined surfaces (47) of a bridge (7a, 7b) of the movement.
12. Movement according to any of claims 1 to 11, characterised in that the axis (12a-12d) of each balance (9a-9d) is substantially secant with the axis (13) of the movement.
13. Movement according to any of claims 1 to 12, characterised in that the driving means (2a, 2b) are shared by all regulating members (5a-5d).
14. Movement according to any of claims 1 to 13, characterised in that the driving means (2a, 2b) comprise a first and a second barrel located on either side of a centre mobile (1) of the movement.

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