CH708960B1 - Tourbillon mechanism and timepiece including such mechanism. - Google Patents

Abstract

The invention relates to a vortex mechanism comprising a cage (4) comprising a shaft shaft (5) forming an axis of rotation of said cage (4), a rocker (1) and an escapement mechanism comprising an escape wheel (3) and possibly an anchor. According to the invention, the cage shaft (5) is mounted through said cage (4) and the rocker (1) comprises a rocker shaft (16) pivotally mounted around the shaft shaft (5). The invention also relates to a timepiece comprising such a tourbillon mechanism.

Description

Description TECHNICAL FIELD [0001] The present invention relates to the field of watchmaking. It relates more particularly to a tourbillon mechanism comprising: - a cage comprising a shaft shaft forming an axis of rotation of said cage, - a beam of radius R, and - an escape mechanism comprising an escape wheel and possibly an anchor .

The present invention also relates to a timepiece comprising such a tourbillon mechanism.

State of the art [0003] The vortex is a rotating regulating system well known to those skilled in the art. It is known that, when the escapement of a mechanical watch is in a vertical position, the inevitable imbalances of the balance and spiral generated by the earth's gravitation cause gait deviations. The purpose of the vortex is to compensate for these variations by making the balance-sprung, in the case of a vortex with a single axis, all the vertical positions.

A vortex is generally composed of a rocker and an escapement mechanism which comprises an escape wheel and, in the case of an anchor escapement, an anchor. These elements are mounted in a rotating cage suspended between two pivot points, which may be located on the plate and the bridge bar or on the cage bridge and the bridge bar. The cage functions as the second mobile. It carries, on its axis, a pinion of second and is driven by the average wheel. Inside the cage, the role of the exhaust is conventional. The force is transmitted from an exhaust pinion coaxial with the escape wheel, this pinion meshing, in the manner of a satellite, with a fixed second wheel, integral with the plate. The tourbillon cage traditionally comprises at least one lower bridge and one upper bridge between which is pivotally mounted the axis of the balance in bearings provided respectively in said lower bridge and said upper bridge. There are also plans for shock absorption. The lower and upper decks are assembled by means of pillars arranged outside the beam of the beam so as not to interfere with its oscillations, generally according to an amplitude of 220 °.

The main disadvantage of this type of cage is a large energy requirement to rotate the cage, because of its large size. There is then less energy available for the pendulum, resulting in a possible loss of precision. In addition the size of the balance is limited by the pillars connecting the lower and upper decks of the cage.

An object of the present invention is therefore to overcome these disadvantages, by proposing a vortex mechanism of original construction and to increase the energy available for the pendulum without impairing the accuracy of a movement comprising such a mechanism swirl.

Disclosure of the invention [0007] For this purpose, and in accordance with the present invention, there is provided a vortex mechanism comprising: - a cage comprising a shaft shaft forming an axis of rotation of said cage, - a beam of radius R and an escape mechanism comprising an escape wheel and possibly an anchor.

According to the invention, the cage shaft is mounted through said cage and the balance comprises a rocker shaft pivotally mounted around the cage shaft.

Advantageously, the mechanism does not include any balance bearing. In addition, the upper deck of the cage is removed so that the diameter of the balance is no longer imposed by the space available between the pillars connecting the lower and upper decks of traditional cages.

According to a preferred embodiment, the cage comprises a lower bridge and an exhaust bridge integral in rotation with the cage shaft and whose ends define a radius Rmax with respect to the axis of rotation of the cage. , Rmax being less than R.

Therefore, the dimensions of the cage are reduced but without affecting the accuracy of the movement. Indeed, the cage being smaller, it requires less energy, and the energy available to power the pendulum is then increased, which increases its precision and its power reserve barrel equal spring.

The invention also relates to a timepiece comprising a vortex mechanism as defined above and a frame comprising a lower plate and an upper bridge, the shaft of the through shaft being pivotally mounted between said lower plate and said upper deck of the frame.

BRIEF DESCRIPTION OF THE DRAWINGS [0013] Other features of the present invention will appear more clearly on reading the description which follows, made with reference to the appended drawings, in which: FIG. 1 is a perspective view of a vortex mechanism according to the invention, FIG. 2 is a perspective view of the tourbillon cage, FIG. 3 is a perspective sectional view of the tourbillon cage and the balance, and FIG. 4 is a bottom view of the vortex mechanism according to the invention.

Embodiment (s) of the invention [0014] As explained above, a vortex is a rotating regulating system, in which a rocker 1, associated with a spiral spring 2, and an escapement mechanism comprising a wheel 3, are mounted in a cage 4. The cage 4 comprises a shaft 5 forming the axis of rotation AA of said cage 4, the cage shaft 5 being pivotally mounted about its axis AA between a plate lower and an upper bridge (not shown) of a frame of a watch movement. In the example illustrated, the escapement also comprises an anchor 6, cooperating with the balance 1 and with the escape wheel 3 by pallets 7.

According to a certain terminology generally used in the field of watchmaking, in a vortex, the pivot axis AA of the cage 4 and the axis of rotation of the balance 1 are merged. There are carousels, in which the balance and the cage are not coaxial. In the present application, the term vortex used below encompasses these two possibilities of arrangement of the axes of the cage 4 and the balance 1. Thus, although the description which follows will be made with reference to a device in which the axis AA of the cage 4 and that of the balance 1 are confused, the invention can be directly transposed to a carousel in the usual sense of the term.

The cage 4 comprises a lower bridge 8 and an exhaust bridge 10 integral in rotation with the shaft shaft 5 between which are mounted pivoting the escape wheel 3 and the anchor 6. In a conventional manner, a exhaust pinion 12, coaxial with the escape wheel 3, is intended to cooperate with a fixed wheel (not shown) integral with the frame of the movement.

Still in a conventional manner, the cage 4 is integral with a drive pinion 14 intended to be kinematically connected to the gear train of the movement.

According to the invention, the cage shaft 5 is mounted through said cage 4 and the rocker 1 comprises a rocker shaft 16 pivotally mounted around the cage shaft 5. More specifically, with reference to FIG. . 3, the shaft of cage 5 is in the form of a pin AA axis terminated at each of its ends by a pivot 5a, 5b respectively directed outwardly of the cage 4. These pivots 5a, 5b are conventional and are intended to cooperate with bearings housed in the lower plate and the upper bridge (not shown) of the frame. Starting from the bottom upwards, after the pivot 5b, the shaft of the shaft 5 passes through the drive gear 14 which it is integral, then comprises a base 18 on which is fixed the lower bridge 8 as it is will see below. Then the shaft of the shaft shaft 5 has a shoulder 20 on which the rocker and then a shoulder 22 on which is positioned a bridge bolt 24, and finally the pivot 5a.

The rocker shaft 16 is hollow and is in the form of a pivotally mounted tube, and thus free to rotate around the shaft of the cage shaft 5. At the lower end of its tube , the balance shaft 16 comprises a base 25 secured to the tube, and resting on the shoulder 20 of the shaft shaft 5. Drilled stones 26, concentric with the shaft of the shaft shaft 5 are provided at the ends of the tube.

The base 25 constitutes the balance plate and can be in the form of a double-plate provided with an ankle cooperating with the exhaust and a notch for the passage of the dart 32. In a variant not shown, the base of the balance plate can be arranged in the form of a simple tray.

The hairspring 2 is fixed to the tube of the rocker shaft 16 via a ferrule 34 and to the bolt bridge 24 via a pin 36 (see Fig. 1). The bridge-stud bolt 24 is secured to the shaft shaft 5.

Thus, in accordance with the invention, the conventional balance shaft is removed, so that the upper bridge of the traditional vortex and balance bearings in which traditionally pivots the axis of the balance, are also removed. The base 18 of the cage shaft 5 and the stud bridge 24 define the lower and upper contours of the cage 4 within which the rocker 1 and the balance shaft are positioned. The traditional upper deck being removed, the tourbillon cage no longer includes pillars connecting the lower and upper decks of traditional cages, so that the diameter of the pendulum is no longer imposed. This construction also has the advantage that the number of parts to be manufactured is reduced compared to a traditional vortex. The different parts are also simpler and more economical to manufacture.

Similarly, the anti-shock devices traditionally provided at the ends of the axis of the balance are removed.

The balance 1 comprises an annular serge 28 or any other suitable form, and three arms 30 connecting the serge 28 to the tube of the balance shaft 16. The serge 28 has an inner radius R relative to its axis of rotation . In the case where the beam serge is not annular, the radius R is defined as being the closest distance between the inner face of the serge and the axis of rotation of the balance. In the following in the description, the expression "the radius R of the pendulum" corresponds to these two definitions.

In the embodiment shown, the ends of the lower bridge 8 and the exhaust bridge 10 define a radius Rmax with respect to the pivot axis AA of the cage 4, where Rmax is less than R. It is it is obvious that the lower bridge and the escape bridge can also define a radius Rmax with respect to the pivot axis AA of the cage 4, where Rmax is greater than R.

Advantageously, the lower bridge 8 comprises a central body 38, annular and integral with the base 18 of the shaft shaft 5. The lower bridge 8 also comprises a structure 39 integral with the central body 38, the spaces between the central body 38 and the structure 39 being hollowed out. The exhaust bridge 10 has the form of a recessed structure at its center and secured to the lower bridge 8 by connecting means. In a particularly preferred manner, said connection means of the lower bridge 8 and the exhaust bridge 10 are pillars 40.

More specifically, as shown in the variant shown in FIG. 4, the structures of the lower bridge 8 and the exhaust bridge 10 have superimposed triangular general shapes, two of the triangular apices corresponding to the points of attachment by the pillars 40, and the third vertex corresponding to the axis of pivoting of the anchor 6. To this end, there are provided at the third vertex of each triangular structure stones 41 with which cooperate pivots which is provided with the anchor 6. For each structure, the smallest side of the triangle comprises two arms 42 whose junction with those of the other structure, corresponds to the axis of pivoting of the escape wheel 3. For this purpose, it is provided at the junction of the arms 42 of each triangular structure stones 43 with which cooperate pivots which is provided the escape wheel 3. It is obvious that other forms of structures are possible, these forms being chosen for example to represent the logo of a mark.

The lengths of the sides of the triangular structures of the lower bridge 8 and exhaust 10 and the arms 42 and the bolt carrier, and the diameter of the base 18 and the central body 38 are smaller than the radius R of the balance so that the cage 4 and the exhaust are inscribed inside the serge 28 of the balance 1, as shown in FIG. 4.

Thus, the construction of the tourbillon described above provides an extremely light and ventilated structure. In addition, the tourbillon cage does not include a pillar connecting a lower bridge to an upper bridge, the pendulum can oscillate regardless of its diameter. The amplitude of the pendulum is not altered.

Examples have been made with two conventional vortices (Example 1 relates to a small vortex, and Example 2 relates to a large vortex), a vortex as described in EP 2 189 855 (Example 3), and a vortex according to the invention (Example 4).

The following parameters are used: Q is the quality factor of the balance I is the inertia of the pendulum lT is the inertia of the vortex A is the geometric transfer coefficient.

By increasing I, the inertia of the balance, we increase the quality factor. By minimizing lT, the inertia of the vortex reduces losses. Compared to a vortex occupying the same volume, we will have more energy in the balance, and for the same energy available.

We can therefore have more regulating energy.

The characteristics of the different vortices and the results obtained are shown in the table below: At a frequency of 3 Hz, we have A = 0.023 and Q = 200

Claims (7)

This shows that the tourbillon cage according to the invention is particularly powerful. The radius of gyration is almost zero. The ratio l / lj is particularly improved. Furthermore, the present invention facilitates balancing. Indeed, the pendulum being larger than the tourbillon cage, it is the balance of the pendulum which is the most influential. Balancing a balance is better controlled than that of a cage. In addition, the cage is located inside the balance and being smaller, its center of gravity is closer to the theoretical axis. Balancing is better and easier to achieve. claims 1. A vortex mechanism comprising: - a cage (4) comprising a shaft shaft (5) forming an axis of rotation (AA) of said cage (4), - a beam (1) of radius R, and - a mechanism exhaust comprising an escape wheel (3) and possibly an anchor (6), characterized in that the shaft (5) is mounted through said cage (4) and in that the balance (1) comprises a balance shaft (16) pivotally mounted around the shaft shaft (5). 2. Tourbillon mechanism according to one of claims 1, characterized in that the cage (4) comprises a lower bridge (8) and an exhaust bridge (10) integral in rotation with the shaft shaft (5) , the lower bridge (8) comprising a central body (38) integral with the shaft shaft (5) and the exhaust bridge (10) having the form of a hollowed out structure at its center and made integral with the lower bridge (8) by connecting means. 3. Tourbillon mechanism according to claim 2, characterized in that the connecting means of the lower bridges (8) and exhaust (10) are pillars (40). 4. Tourbillon mechanism according to one of the preceding claims, characterized in that it comprises a stud bridge (24) integral with the shaft cage (5). 5. Tourbillon mechanism according to one of the preceding claims, characterized in that the rocker shaft (16) comprises a base (25) forming the balance plate and in that the cage shaft (5) comprises a shoulder (20) on which said base (25) of the balance (1). 6. A vortex mechanism according to claim 2, characterized in that the ends of the lower bridge (8) of the exhaust bridge (10) define a radius Rmax with respect to the pivot axis (AA) of the cage (4). ), where Rmax is less than R, the beam radius (1). 7. Timepiece comprising a vortex mechanism according to one of the preceding claims and a frame comprising a lower plate and an upper bridge, characterized in that the shaft shaft (5) through is pivotally mounted between said lower plate and said upper deck of the frame.