EP2177959B1 - Mechanism for driving hands - Google Patents

Description

The invention relates to a needle display mechanism, and in particular to a timepiece, or other display device, having a non-planar dial.

A timepiece conventionally comprises a driving member, a regulating member, and a gear mechanism, which serves to reduce the speed of movement of the regulating member and to transmit this reduced motor movement to a display member, such as a needle combined with a dial. A conventional gear mechanism comprises a plurality of gear wheels with parallel axes.

In a classic timepiece, the hands (hours, minutes, seconds, etc.) are driven in planes that are substantially parallel to one another, and each needle describes a circle in a plane parallel to that of the dial of the piece. that is, the conventional needle path is essentially two-dimensional. It is known to form the dial and the needles with a certain curvature to produce a more three-dimensional effect, but the trajectories of these curved needles remain essentially circular and two-dimensional.

To achieve a three-dimensional trajectory of the needles, it has been proposed ( WO02 / 101473A1 , Wolf and Sporrer) a clock with a classic movement, a three-dimensional surface dial and rotating hands, as they follow the surface of the dial during their rotation. In this system, the movement in the third dimension, that is to say the direction parallel to the axis of rotation of the needles, is formed, on the one hand, by a pivot axis for each needle and, d ' on the other hand, by a mechanism of blades between the classical movement and the needles. This blade and swivel system is complex to manufacture, is bulky, can introduce unwanted play into the pivot axes, and inevitably generates additional friction that can begin to prevent needle movement.

One result that the present invention aims to achieve is a three-dimensional needle drive mechanism which allows for a less complex and more compact construction, and a smoother movement of the needles, without introducing additional friction.

For this purpose, the subject of the invention is a device according to claim 1, as well as a timepiece according to claim 15. The preferred embodiments are described in the dependent claims 2 to 14.

• figure 1, un exemple d'une trajectoire tridimensionnelle suivie par une aiguille solidaire d'une roue satellite tournant à l'extérieur d'une couronne,
• figure 2, un exemple d'une trajectoire tridimensionnelle suivie par une aiguille solidaire d'une roue satellite tournant à l'intérieur d'une couronne,
• figure 3, une réalisation de l'invention, avec deux mécanismes et deux aiguilles,
• figures 4 et 5, différentes vues de la réalisation de la figure 3,
• figures 6 et 7, une réalisation de l'invention selon la figure 3, mais avec une seule aiguille et un mécanisme,
• figures 8 et 9, différentes vues de la réalisation de la figure 3,
• figure 10, une réalisation comme celle de la figure 3, dans le contexte d'une pièce d'horlogerie,
• figure 11, une vue agrandie de la prise entre la roue satellite et la couronne de la figure 10,
• figure 12, une vue du plan de la roue satellite, montrant la forme des dents à rattrapage de jeu, et
• figure 13, une vue section, montrant l'inclinaison de la denture de la roue satellite, selon un mode de réalisation de l'invention.

The invention will be better understood on reading the following description given by way of nonlimiting example, by looking at the attached drawings which show schematically and in view of projection:

• figure 1 , an example of a three-dimensional trajectory followed by a needle integral with a satellite wheel rotating outside a crown,
• figure 2 , an example of a three-dimensional trajectory followed by a needle integral with a satellite wheel rotating inside a crown,
• figure 3 , an embodiment of the invention, with two mechanisms and two needles,
• figures 4 and 5 , different views of the realization of the figure 3 ,
• Figures 6 and 7 , an embodiment of the invention according to the figure 3 but with a single needle and a mechanism,
• figures 8 and 9 , different views of the realization of the figure 3 ,
• figure 10 , an achievement like that of the figure 3 , in the context of a timepiece,
• figure 11 , an enlarged view of the hold between the satellite wheel and the crown of the figure 10 ,
• figure 12 , a view of the plane of the satellite wheel, showing the shape of the teeth catching play, and
• figure 13 , a sectional view, showing the inclination of the toothing of the satellite wheel, according to one embodiment of the invention.

The same reference numbers indicate the corresponding elements in the different figures.

In the present application, the term "gearing" is understood to mean not only a toothed gear, but also any kind of known drive means (friction drive, for example) usable between drive elements whose Rotational axes are not parallel. Similarly, the term "needle" does not only include the pointed and narrow shape of a traditional display needle, but also any kind of shape that the skilled person knows to indicate the time by its position relative to the mechanism of his training and / or a dial.

Referring to Figures 1 and 2 two examples of the trajectories (5) that can be realized with a drive device according to the present invention are shown. In both cases shown, the needle (3) is integral with a satellite wheel (2) which rotates around a ring gear (1), and the axis of rotation (11) of the satellite wheel (2) is inclined by an angle (α) relative to the axis of rotation (10) of the planet carrier (4) on which the satellite wheel (2) is mounted. The satellite wheel (2) of the figure 1 turns around the crown (1) and outside the crown (1). On the other hand, the satellite wheel (2) of the figure 2 turns around the crown (1), but inside the crown (1).

The particular trajectory (5) is determined on the one hand by the value of the angle (α) between the axis (11) of rotation of the satellite wheel (2) and the axis (10) of rotation of the carrier. satellite (4), and secondly by the radius of curvature of the toothing of the satellite wheel (2) and the radius of curvature of the toothing of the crown (1).

In the examples of Figures 1 and 2 , the toothing of the satellite wheel (2) and that of the crown (1) have a circular curvature (that is to say a constant radius of curvature), but they can also have an elliptical curvature, or of any shape , as the toothing of the satellite wheel (2) remains substantially in engagement with that of the crown (1). In the context of this patent application, the terms "satellite wheel" and "crown" also include elements of any shape that allow the satellite wheel (2) and the crown (1) to mesh together. If the toothed sector of the crown (1) has a constant radius of curvature, the axis (10) of rotation of the planet carrier (4) can be static relative to the crown (1), which simplifies the construction of the mechanism . By cons, a ring (1) non-circular (elliptical, for example, or shaped "potato"), having a set of teeth with a varying radius of curvature, allows a trajectory (5) much more complex, but also requires an axis of rotation (11) of the satellite wheel (2) which is movable relative to the toothing of the crown (1). Such relative movement can be achieved by providing the planet carrier with means which allow the displacement of the axis of rotation (10) of the planet wheel (2) in a plane substantially perpendicular to the axis of rotation (10) of the satellite wheel (2) and / or a plane which contains the toothing of the crown (1).

Although the mechanisms of Figures 1 and 2 represent (5) complex and relatively long trajectories, it is clear that for the realization of a display such as, for example, a retrograde display or a speedometer of a car, the rotation of the needle could be limited to only a portion of the trajectory, that is to say a portion of a revolution of the satellite wheel relative to the carrier. Similarly, although the satellite wheel (2) and the crown (1) are represented in the Figures 1 and 2 as capable of one or more revolutions, that is to say that each is provided with a toothed sector which extends over its complete circumference, a partial revolution trajectory can also be achieved by a satellite wheel (2) and / or a ring gear (1) having a sector gear on only part of its circumference.

The Figures 3 to 10 show an embodiment of the invention. It will be understood that the device of the invention can be understood as one to two, three or more needles, each with its drive mechanism. In the figures 3,4 , 5 , 8 , 9 and 10 , a layout is presented with two mechanisms and two needles (3), while in the Figures 6 and 7 only a needle and a mechanism are shown. In this embodiment of the invention, each display pointer (3) is mounted integral with a satellite wheel (2) at an angle (α) of the axis of the planet carrier on which it is mounted.

Other elements of the gear and the motor unit are not represented in the Figures 3 to 9 , but the figure 10 shows how a device according to the invention can be made in the context of a timepiece, such as a watch, having two needles both driven in a retrograde manner. In the room represented in the figure 10 two mechanisms driven by the same motor and gear are arranged on a common frame (8), each mechanism having its own retrograde escapement and its own needle drive gear. In this representation, the two mechanisms share a single crown (1), which saves space.

The figures 11 and 12 schematically show a close-up view of the satellite wheel with recoil teeth (20, 21). In this embodiment of the invention, each tooth (20) of the satellite wheel is formed with an elastic portion (21), to eliminate any set of pinion. One can also build the satellite wheel (2) such that every second, every third, etc., tooth is a tooth catching play. Apart from the known advantage of a smoother movement of the needle, the use of Such elastic teeth in the context of the invention has an additional advantage: the geometry of the inclined teeth of the crown and the satellite wheel is relatively complicated to manufacture in a very precise manner, and the use of the elastic teeth can compensate the play due to any inaccuracy of manufacture.

The figure 13 shows in side view section XII-XII of the satellite wheel (2) of the figure 12 . Of the figure 13 we see the angle (β) of the toothing relative to the axis of rotation (11) of the satellite wheel (2). The angle corresponding to the toothing of the crown is denoted here by θ, but is not represented in the FIGS. The angles β and θ, as well as the geometry of the teeth, are chosen in order to achieve an effective gearing between the satellite wheel (2) and the crown (1) at the angle α. These angles of inclination of the teeth of the crown and the satellite wheel are also visible on the figure 4 . The angles shown are for example only, and can be chosen from any combination of angles (α, β, θ) allowing the realization of the desired trajectory (5).

Claims (15)

1. Device for driving at least one display hand (3) according to a three-dimensional path (5), the device comprising a first gear mechanism for transmitting the force and motion of a motor organ to a display hand (3), the device being characterised in that:

   the first gear mechanism comprises a first gear part (1), referred to as crown, having at least one curved toothed or friction sector;

   the first gear mechanism further comprises a second gear part (2), referred to as planetary wheel, in engagement with the said curved sector of the crown (1), the said planetary wheel (2) having a first axis of rotation (11), referred to as axis of the planetary wheel, the planetary wheel (2) being supported in a rotational way by a planetary wheel carrier (4), the planetary wheel carrier (4) having a second axis of rotation (10), referred to as axis of the planetary wheel carrier (10), the said planetary wheel carrier (4) being designed to be driven in rotation by the motor organ such that, when the planetary wheel carrier (4) is driven in rotation, the planetary wheel (2) is thus driven in rotation in engagement with the said curved sector of the crown (1);

   the axis of the planetary wheel (11) is disposed at an angle (α), referred to as angle of inclination of the planetary wheel, with respect to the axis of the planetary wheel carrier (10);

   and in that the planetary wheel (2) is designed to drive the display hand (3) in rotation about a third axis (12), referred to as axis of rotation of the hand, substantially parallel to the axis of the planetary wheel (11).
2. Device according to claim 1, wherein the three-dimensional path (5) followed by the display hand (3) is determined by the geometry of the said gear parts, by the angle of inclination of the planetary wheel (α), and by the extent of the rotation of the planetary wheel carrier (4).
3. Device according to claim 1, wherein the toothing of the toothed curved sector of the crown (1) is inclined with respect to the plane of the crown (1).
4. Device according to one of the claims 1 or 2, wherein the planetary wheel (2) comprises a toothing inclined with respect to the plane of rotation of the planetary wheel (2).
5. Device according to one of the claims 1 or 2, wherein the axis of the planetary wheel (11) and the axis of rotation of the hand (12) are parallel and/or collinear.
6. Device according to any one of the preceding claims, wherein the curved sector of the crown (1) has a circular or elliptical curvature..
7. Device according to any one of the preceding claims, wherein the meshing of the curved sector is on the outside of the periphery of the crown (1).
8. Device according to any one of the preceding claims, wherein the axis of the planetary wheel (11) and the axis of rotation of the hand (12) are separate such that the display hand (3) is mounted eccentrically on the planetary wheel (2).
9. Device according to any one of the preceding claims, wherein the geometry of the crown (1), the geometry of the planetary wheel (2), the geometry of the planetary wheel carrier (4) and the angle of inclination of the planetary wheel (α) are such that the path (5) of the display hand (3) forms a section of the surface of a cone.
10. Device according to any one of the preceding claims, wherein the mechanism is designed to be supported by the frame (7) of a horological or display piece, and wherein the crown (2) is designed to be fixed with respect to the frame (7).
11. Device according to any one of the preceding claims, further comprising a three-dimensional dial (6) of such a shape that the path (5) of the display hand (3) is substantially parallel to the surface of the dial (6).
12. Device according to any one of the preceding claims, further comprising a second mechanism for driving the planetary wheel carrier (4) such that the planetary wheel carrier (4) is designed to drive the display hand (3) in a reciprocating way, referred to as retrograde, between a position of origin and an end position of the three-dimensional path (5).
13. Device according to claim 12, wherein the movement of the display hand (3) between the position of origin and the end position is substantially faster in one direction than in the other.
14. Device according to any one of the preceding claims, comprising at least two display hands (3) having a three-dimensional path (5) driven by at least two of the said first gear mechanisms, the toothed sectors of the crowns (1) of at least two of the said first gear mechanisms being disposed on the same crown (1).
15. Horological piece comprising a drive device according to any one of the preceding claims.

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