WHEEL FOR A REDUCED INCLINATION SYSTEM

Description

Technical field of the invention

[0001] The invention falls within the field of watchmaking, and in particular mechanical watch movements.

[0002] More specifically, the invention relates to a wheel for an escapement system for a watch part. Technological background

[0003] An escape wheel is well known in the field of watchmaking and is designed to be connected to a mainspring which supplies it with energy in order to maintain the oscillations of a balance wheel, possibly via an anchor.

[0004] More specifically, in the Swiss lever escapement, the escape wheel has teeth distributed around the periphery of a rim connected to a hub by radial arms. The lever has pallets designed to cooperate with the teeth of the escape wheel.

[0005] With each swing of the balance wheel, the escape wheel follows this cycle: it is released from its resting position against the first pallet fork, then accelerated and driven by the gear train to catch first the anchor and then indirectly the balance wheel through the anchor. It drives the balance wheel before ejecting it, and finally completes its travel by coming to rest against the second pallet fork.

[0006] Each of these repeated cycles is therefore a succession of wheel steps, which start, stop, and so on. It is thus clear that the lowest possible inertia of this moving part plays an important role in ensuring a rapid start and recovery of the balance wheel, guaranteeing limited efficiency losses.

[0007] Such a problem is known and the skilled have addressed it in the past in various ways, namely by making a skeletonized escape wheel or by making an escape wheel out of low density material such as silicon, the aim being to reduce inertia as much as possible.

[0008] Although these solutions are satisfactory, manufacturing such an escape wheel presents some difficulties. In particular, in addition to being relatively time-consuming to machine, the resulting components can exhibit increased fragility due to the skeletonization or the properties of the silicon material.

[0009] Document DE 19 81 274 U presents escape wheels including a recess on one face. Summary of the invention

[0010] The main purpose of the present invention is to provide a wheel for an exhaust system with reduced inertia compared to currently used wheels, while remaining easy and quick to manufacture.

[0011] To this end, the invention relates to a wheel for an escapement system comprising a hub intended to be mounted rotationally fixed with an axle, the axle being intended to be subjected to a mechanical torque, a rim, at least two arms extending from the hub to the rim, and a toothing formed by a plurality of teeth, said wheel for the escapement system comprising a bore on its two faces, said front face and rear face, each bore extending from the rim to the hub.

[0012] In accordance with other advantageous variants of the invention: The wheel has a thickness of at least 0.10 mm; at least one groove has a height between 0.02 mm and 0.05 mm; at least one groove extends partially onto the rim and forms a border of at least 0.02 mm; the wheel has at least two arms, and preferably four arms; the grooves are symmetrical with respect to a horizontal plane at mid-thickness of the escape wheel; the grooves are asymmetrical with respect to a horizontal plane at mid-thickness of the escape wheel; the wheel is made of a material chosen from steel, silicon or a metal alloy; at least one groove is made by milling, turning, sinking, laser machining, DRIE or LIGA; the wheel is an escape wheel, an intermediate wheel or a seconds wheel; several grooves per face may be envisaged.

[0013] The invention also relates to an escapement system comprising a wheel according to the invention.

[0014] The invention also relates to a watch movement comprising such an escapement system or a wheel for an escapement system according to the invention. Brief description of the figures

[0015] Other features and advantages of the invention will become apparent from the following detailed description, given by way of non-limiting example, with reference to the accompanying drawings in which: there figure 1 represents a perspective view of an escape wheel according to the invention; the figure 2 represents a cross-sectional view along axis AA of the escape wheel of the figure 1 ; there figure 3 represents a top view of the escape wheel according to the invention. Detailed description of the invention

[0016] The invention relates to a wheel for an escapement system; such a wheel is, for example, an escape wheel, an intermediate wheel, or a seconds wheel. In the following description, the escape wheel is used as an example to facilitate understanding of the invention. It is clear that a person skilled in the art would have no difficulty in making an intermediate wheel or a seconds wheel in a similar manner.

[0017] There figure 1illustrates an escape wheel 1 according to the present invention, conventionally comprising a hub 2 connected to a rim 3 by radial arms 4, and teeth 5 distributed regularly around the periphery of the rim 3 and extending in orthoradial directions with respect to an axis of rotation of the escape wheel 1. The escape wheel 1 comprises at least two arms 4, and preferably four arms 4. Obviously, other configurations can be envisaged, such as an escape wheel with three arms 4.

[0018] The escape wheel 1 is made of a material chosen from steel, silicon or a metal alloy, or any other conventional material known to those skilled in the art for making components for watch parts.

[0019] In this text, a plane P is defined as perpendicular to the axis of rotation of the escape wheel 1 and at mid-thickness of the escape wheel. Furthermore, the term "thickness" used in the remainder of the text refers to a dimension considered along a direction parallel to the axis of rotation of the escape wheel 1.

[0020] As depicted on the figure 1 , each of the teeth 14 has an end with at least one bevel.

[0021] According to the invention, the escape wheel 1 comprises at least one core 10 formed on at least one of its faces, namely the front face and / or the rear face, the core 10 extending from the rim 3 to the hub 2. According to the needs of those skilled in the art, the hub 2 may be of the same thickness as the rim 3 so that the wheel 1 is more solid at the hub and avoid deformations when it is placed on an axle.

[0022] By noyure, we mean a groove, for example circular in shape, made in the wheel plate 1.

[0023] By front face and rear face, we mean the faces visible from above and below the exhaust wheel 1.

[0024] The escape wheel has a minimum thickness of 0.10 mm and the bore(s) 10 have a height between 0.02 mm and 0.05 mm. The thickness of the escape wheel 1 at the bore 10 is typically between 0.05 mm and 0.10 mm.

[0025] As can be seen, at least one groove 10 extends partially onto the rim 3 and forms a border 6 at the rim edge of at least 0.02 mm. With such an arrangement, the rim 3 retains a portion of its thickness at the periphery of the escape wheel, thus preserving its rigidity.

[0026] According to one embodiment of the invention, the escape wheel 1 comprises a groove 10 on each of its faces, namely the front face and the rear face.

[0027] According to one embodiment of the invention, the grooves 10 can be made symmetrical with respect to the horizontal plane P in which the escape wheel 1 is inscribed and which is formed by the arms 4 and the rim 3 of the escape wheel 1. By symmetrical, it is understood that each groove has an identical diameter and height on each face of the escape wheel. For example, the two grooves 10 can have a diameter of 3.3 mm and a height of 0.04 mm.

[0028] According to another embodiment of the invention, the grooves 10 can be asymmetrical with respect to the horizontal plane P in which the escape wheel 1 is inscribed and which is formed by the arms 4 and the rim 3 of the escape wheel 1. By asymmetrical, it is understood that each groove has a different height on each face of the escape wheel but an identical diameter. For example, the two grooves 10 can have the same diameter and each have a height of 0.02 mm and 0.05 mm.

[0029] Other configurations of the 10 sockets can obviously be envisaged according to the needs of the person skilled in the art without having to make any special effort to make the escape wheel 1. For example, the front or rear face can have several sockets, such as one socket per inter-arm space.

[0030] At least one recess 10 of the escape wheel 1 can be made using methods well known to those skilled in the art, for example by milling, turning, sinking, laser machining, DRIE or LIGA depending on the material chosen for the manufacture of wheel 1.

[0031] The invention also relates to an escapement system comprising a wheel 1 according to the invention. The wheel of the escapement system is an escapement wheel, an intermediate wheel, or a seconds wheel.

[0032] The invention also relates to a watch movement comprising an escapement system or a wheel according to the invention.

[0033] Thanks to these different aspects of the invention, we have an escape wheel with reduced inertia which is easier and less expensive to make than a skeletonized escape wheel, for example.

[0034] Of course, the present invention is not limited to the illustrated example and is susceptible to various variants and modifications which will appear to a person skilled in the art, without departing from the scope of the invention as defined by the claims.

Claims

1. Wheel (1) for an escapement system comprising a hub (2) intended to be mounted with a staff for rotation therewith, the staff being intended to be subjected to a mechanical torque, a felloe (3), at least two arms (4) extending from the hub (2) to the felloe (3), and a toothing formed by a plurality of teeth (5), said wheel for the escapement system (1) comprises a recess (10) on the two faces thereof, referred to as the front face and the rear face, each recess (10) extending from the felloe (3) to the hub (2).

2. Wheel (1) for an escapement system according to claim 1, characterised in that it has a thickness of at least 0.10 mm.

3. Wheel (1) for an escapement system according to claim 1 or 2, wherein the at least one recess (10) has a height of between 0.02 mm and 0.05 mm.

4. Wheel (1) for an escapement system according to one of claims 1 to 3, wherein the at least one recess (10) extends partly over the felloe (3) and forms a border (6) at the edge of the felloe of at least 0.02 mm.

5. Wheel (1) for an escapement system according to one of claims 1 to 4, characterised in that it comprises at least two arms (4), and preferably four arms (4).

6. Wheel (1) for an escapement system according to one of claims 1 to 5, wherein the recesses are symmetrical relative to a horizontal plane (P) formed by the arms (4) and the felloe (3) of the escape wheel.

7. Wheel (1) for an escapement system according to one of claims 1 to 6, wherein the recesses are asymmetrical relative to a horizontal plane formed by the arms (4) and the felloe (3) of the escape wheel.

8. Wheel (1) for an escapement system according to one of claims 1 to 7, characterised in that it is made of a material selected from steel, silicon or a metal alloy.

9. Wheel (1) for an escapement system according to one of claims 1 to 8, characterised in that said at least one recess (10) is produced by milling, turning, sinking, laser machining, DRIE or LIGA.

10. Wheel (1) for an escapement system according to one of claims 1 to 9, characterised in that the wheel is an escape wheel, an intermediate wheel or a fourth wheel.

11. Escapement system comprising a wheel (1) for an escapement system according to one of claims 1 to 10.

12. Horological movement comprising an escapement system according to claim 11 or an escape wheel (1) according to one of claims 1 to 10.