Patent Application
20160139563
This application claims priority from European patent application No. 14193348.1 filed Nov. 14, 2014, the entire disclosure of which is hereby incorporated herein by reference.
The present invention concerns an annular oscillating weight comprising a drive ring including an annular transmission portion provided with a toothing coaxial to the ring, and a heavy sector secured to the drive ring. The present invention also concerns a timepiece movement and a self-winding timepiece which respectively comprise the annular oscillating weight of the invention.
There are known self-winding watches equipped with an annular oscillating weight. This oscillating weight is accommodated in a circular passage provided around the movement inside the watch case. Bearing rollers are also arranged at the side of the passage to support and guide the oscillating weight, so that it is free to rotate inside the passage. The drive ring may, for example, have an inner toothing, by means of which the rotational movements of the oscillating weight are mechanically transmitted to the barrel of the movement. The oscillating weight thus ensures the self-winding of the mainspring.
The function of the bearing rollers is to guide the ring and to limit friction as much as possible. To this end, they are preferably mounted on ball bearings. To provide a stable base for the oscillating weight, the bearing rollers must be at least three in number. A known problem with annular oscillating weights matching the above description relates to the relative fragility of the rollers in view of the considerable inertia of the oscillating weight. Indeed, in the event of a radially exerted shock on the timepiece case middle, the considerable weight of the oscillating weight may, for example, lead to rupture of the arbor of the bearing rollers, or alternatively cause the ball bearings to seize up. Further, in the event of a shock on the back cover side or the dial side of the timepiece, the axial motion of the oscillating weight risks damaging the toothed wheel which meshes with the drive ring.
In order to at least partially overcome the aforementioned problems, CH Patent No 701343B1 proposes to mount each of the bearing rollers on a damper member preferably formed by a spring loaded lever. The function of the damping members is to dampen any inadvertent motion of the oscillating weight in the radial direction following a shock. It will be understood, however, that the solution proposed by the aforementioned Patent document does not enable motions of the oscillating weight to be damped in the axial direction.
It is an object of the present invention to overcome the problems of the prior art that have just been described. This object is achieved by providing an annular oscillating weight in accordance with the annexed claim 1.
According to the invention, the annular transmission portion of the drive ring and the heavy sector are directly or indirectly connected to each other. Further, the connection between the annular transmission portion and the heavy sector is achieved by means of a plurality of elastically deformable connecting elements. It will be understood, therefore, that in the event of shock, the heavy sector has the possibility of moving away from its normal trajectory to a certain point without the annular transition portion being forced to do the same regardless of whether the motion of the weight after the shock is radial or axial. The coaxial toothing is carried by the annular transmission portion and it will therefore be understood that the presence of deformable connecting elements to a certain extent allows the heavy sector to be mechanically uncoupled from the coaxial toothing. In particular, when a shock causes a sudden acceleration of the heavy sector, the deformable connecting elements can dampen this acceleration, and thereby prevent the gear arrangement between the drive ring and the winding device being damaged.
According to an advantageous embodiment of the invention, the elastically deformable connecting elements are formed by flexible elastic pins. This feature gives the heavy sector the possibility of moving away from its normal trajectory in all directions relative to the annular transmission portion. According to an advantageous variant of this embodiment, the longitudinal arbors of the flexible rods preferably extend in the same plane parallel to the drive ring. One advantage of this feature is that the rods oppose the same return force to an upward axial force as to a downward axial force.
According to an advantageous embodiment, the flexible rods exhibit at least one fork. According to a first variant of this particular embodiment, the rods have a general Y-shape with a single fork. According to a second variant, the rods fork in two places, on either side of the middle of the pin. In other words, according to the second variant, the rods include two opposite forks which give them a general double Y-shape. According to either of the latter two variants, the forked portions of the rods are preferably also contained in the plane parallel to the drive ring in which the longitudinal arbor extends. As will be seen in more detail below, the fact that the branches have forks contained in a plane parallel to the drive ring has the advantage of increasing the return force in the event of force in a tangential direction to the ring.
The invention also includes a self-winding timepiece movement according to claim 10 of the Patent and a self-winding timepiece according to claim 11 of the Patent.
Other features and advantages of the invention will appear upon reading the following description, given solely by way of non-limiting example, with reference to the annexed drawings, in which:
Referring to
The oscillating weight 3 shown in
Bearing rollers 19 are preferably equipped with ball bearings (not shown). The function of the bearing rollers is to support and guide the oscillating weight, so that it is free to rotate about the circle passing through the three ball bearings. Referring more particularly to the sectional view of
As already stated, according to the invention, oscillating weight 3 of the present example is arranged for damping shocks. First of all, it is well known that when a small object such as a watch receives a shock, it undergoes a sudden acceleration in the direction of the shock. In the case which concerns us, where the object in question is the timepiece of the present example, the sudden acceleration of the timepiece is transmitted to the oscillating weight which it contains by means of bearing rollers 19. Since the inertia of oscillating weight 3 is essentially localised in heavy sector 7, the latter exerts a considerable inertial force on the rest of the oscillating weight. In the case where this inertial force is oriented in the radial direction (parallel to the plane of drive ring 5 and in the direction of the axis of rotation of the oscillating weight), it produces a motion of annular portion 13 relative to annular transmission portion 11 in the plane of the drive ring. It will be understood that, according to the invention, this motion is made possible by the deformation of the connecting elements (in the present example, the bending deformation of rods 9 or their fork), and that this motion contributes to damping the shock, and in particular to protecting the ball bearings of rollers 19.
In the case where the inertial force is exerted by heavy sector 7 in a tangential direction (in a direction tangent to drive ring 5 and parallel to the plane of the ring), the inertial force tends to suddenly rotate second annular portion 13 of drive ring 5. It will be understood that, according to the invention, this sudden movement can be damped by means of the bending deformation of rods 9. The flexible rods prevent the torque exerted by inner toothing 15 on the winding wheel set exceeding an admissible value. Any breakage of the self-winding mechanism can therefore be avoided.
It was seen that bearing rollers 19 are arranged to hold oscillating weight 3 not only radially, but also axially as a result of the cooperation between equatorial bulge 23 and groove 21. The bearing rollers thus also transmit to the oscillating weight the acceleration produced by an axial shock exerted on the back cover side or dial side of the timepiece. In such case, the heavy sector exerts a considerable inertial force in the axial direction (perpendicular to the plane of the drive ring) on the rest of the oscillating weight. This force produces a motion of second annular portion 13 relative to annular transmission portion 11. This motion is oriented perpendicularly to the plane of drive ring 5. It will be understood that, as previously, this motion is made possible by the bending of rods 9, and that this motion protects the bearing rollers and the winding wheel set by damping the shock experienced by the timepiece.
It will also be clear that various alterations and/or improvements evident to those skilled in the art may be made to the embodiment forming the subject of the present description without departing from the scope of the present invention defined by the annexed claims. In particular, rather than being arranged around the annular transmission portion, according to a variant, the second annular portion could be disposed concentrically to the inside of the annular transmission portion. Further, the elastically deformable connecting elements are not necessarily formed by flexible pins. Indeed, these connecting elements could alternatively be formed by levers (three or more in number) each associated with a spring.
The drive ring of the invention may be formed from a material including silicon, namely, for example single crystal silicon, polycrystalline silicon, doped single crystal silicon, doped polycrystalline silicon, doped or undoped silicon carbide, doped or undoped silicon nitride, doped or undoped silicon oxide such as quartz or silica. Anisotropic etching of such materials may be achieved by wet means or by dry means and typically by deep reactive ion etching or DRIE.
Alternatively, the drive ring of the invention may be formed of precious or non-precious metal, typically by the electroforming technique known by the abbreviation L.I.G.A. from the German term ‘RöntgenLithographie, Galvanoformung & Abformungand’ wherein a mould is filled to one or more levels with the aid of a metal, for example, by means of electroplating. Of course, any type of electroforming process capable of forming a one-piece drive ring with one or more levels may be envisaged, whether or not it is of the L.I.G.A. type.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14193348.1 | Nov 2014 | EP | regional |
