Balance wheel with inertia adjustment

Abstract

The present invention relates to a balance wheel for a watch movement. The balance wheel includes a rigid part that includes a hub defining the pivot axis of the balance wheel, a rim, and four arms connecting the rim to the hub. The balance wheel also includes four slots for receiving and clamping inertia blocks in place. Each slot is bounded on one hand by an arm and on the other hand by an elastic arm. The elastic arm includes a first end integral with the arm and a second distal end that is free relative to the hub, the arm, and the rim. According to the invention, the balance wheel includes two pairs of inertia blocks, each pair having a different mass to ensure different adjustment capabilities. The first pair of inertia blocks is for basic adjustment, and the second pair of inertia blocks is for precise adjustment.

Description

Technical Field

[0001] The present invention relates to a balance wheel with inertia adjustment, which has means for adjusting inertia.

[0002] The present invention also relates to a watch movement including such a system, and a watch equipped with such a movement. Background Art

[0003] A balance wheel is known, the moment of inertia of which can be adjusted by adjustment screws provided around its periphery. This type of device is known especially in mechanical oscillators, the fundamental frequency of which is adjusted by the moment of inertia of the balance wheel. Generally, such a balance wheel includes a rim, arms, and screws or inertia blocks arranged in a certain structure fastened to the rim or arms of the balance wheel. By adjusting the position of the screws or inertia blocks, the moment of inertia of the balance wheel can be changed. These screws or inertia blocks are positioned by a wrench or a screwdriver so that their positions can be adjusted.

[0004] For example, from patent CH264669, a balance wheel with adjustment screws without heads is known, which are screwed into and embedded in its thickness from the outside of the balance wheel rim. This embodiment advantageously aims to replace a balance wheel equipped with screws whose heads are arranged to protrude around the periphery of the rim or are located in the hollow part of the rim.

[0005] From patent EP1837719B1, a balance wheel rim is also known, which includes columns radially pointing towards the inside of the balance wheel, and each column is provided with a threaded hole for receiving an inertia block screwed in from the inside of the balance wheel. In this structure, it is not easy to hold the inertia block, so there is a risk of scratching the balance wheel rim during the adjustment process.

[0006] These balance wheels with adjustment screws have another disadvantage, that is, it is difficult to ensure adjustment during the operation of the movement, and one or more screws may become partially or completely unscrewed, which is harmful to the correct operation and regularity of the balance wheel. Summary of the Invention

[0007] In particular, the object of the present invention is to overcome the various disadvantages of these known techniques.

[0008] More specifically, an object of the present invention is to provide a balance wheel with inertia adjustment to achieve simple and rapid adjustment.

[0009] At least in one specific embodiment, another object of the present invention is to provide a balance wheel with inertia adjustment, which is easy to implement and has a low production cost.

[0010] According to the present invention, these and other objects which will become apparent hereinafter are achieved by means of a balance wheel for a timepiece movement, said balance wheel comprising a rigid part which includes a hub defining the pivot axis of said balance wheel, a rim, and four arms connecting said rim to the hub, and said balance wheel comprising four slots for receiving and holding in place inertial blocks, each slot being delimited on the one hand by an arm and on the other hand by a resilient arm which includes a first end integral with said arm and a second distal end which is partially free with respect to said hub, said arm, and said rim.

[0011] According to the present invention, said balance wheel comprises two pairs of inertial blocks, each pair of inertial blocks having a different mass to ensure different adjustment capabilities, a first pair of inertial blocks being for basic adjustment and a second pair of inertial blocks being for fine adjustment.

[0012] According to other advantageous variants of the present invention:

[0013] - Each pair of inertial blocks has a different size, the first pair of inertial blocks being larger than the second pair of inertial blocks, or vice versa;

[0014] - The first pair of inertial blocks is heavier than the second pair of inertial blocks, or vice versa;

[0015] - The pairs of inertial blocks are made of different materials;

[0016] - The first pair of inertial blocks and the second pair of inertial blocks are arranged at different radii of the balance wheel;

[0017] - The first pair of inertial blocks is arranged at a first radius close to the rim and the second pair of inertial blocks is arranged at a second radius close to the hub of the balance wheel;

[0018] - Said arms, rim, and hub form a single-piece element.

[0019] The present invention also relates to a timepiece movement comprising a balance wheel according to the present invention.

[0020] The present invention also relates to a timepiece comprising a timepiece movement according to the present invention. Description of the Drawings

[0021] Other features and advantages of the present invention will become more apparent upon reading the following description of specific embodiments of the present invention and the drawings, which description is given by way of simple illustrative and non-limiting examples, wherein:

[0022] - Figure 1 is a perspective view of a balance wheel according to a first embodiment of the present invention. Detailed Description

[0023] The balance wheel 1 for a watch movement is equipped with means for adjusting its inertia, such that the oscillation frequency of said balance wheel can be adjusted. The balance wheel 1 includes a rigid part, which includes a hub 2 defining the pivot axis A of the balance wheel 1, a circular rim 3, and four arms 4 connecting said rim 3 to the hub 2. And the balance wheel 1 includes four slots 7 for receiving and clamping the inertia blocks 6, 6' in place.

[0024] Each slot 7 is bounded on one hand by an arm 4 and on the other hand by an elastic arm 5, which includes a first end 5B integral with said arm 4 and a second distal end 5A free with respect to said hub 2, said arm 4, and said rim part 3.

[0025] As shown, the balance wheel 1 includes four arms that form a hub 2 at their intersection. The hub 2 is equipped with a hole 40 for receiving the balance staff.

[0026] The slot 7 is bounded by the rigid part of the arm 4 and the elastic arm 5. When the inertia block is inserted into the slot 7, the elastic arm 5 continuously returns towards the arm 4.

[0027] According to the invention, the balance wheel includes two pairs of inertia blocks 6, 6', each pair of inertia blocks having different sizes to ensure different adjustment capabilities. The first pair of inertia blocks 6 is for basic adjustment, and the second pair of inertia blocks 6' is for precise adjustment.

[0028] Each pair of inertia blocks 6, 6' is relatively arranged in the slot 7 with respect to the pivot axis A of the balance wheel, or is also arranged symmetrically with respect to the axis A, for balancing the mass distribution on the balance wheel 1.

[0029] To distinguish between the inertia blocks 6, 6' and position them correctly, the first pair of inertia blocks 6 is larger than the second pair of inertia blocks 6', or vice versa.

[0030] According to an embodiment of the invention, the first pair of inertia blocks 6 and the second pair of inertia blocks 6' are arranged at different radii of the balance wheel.

[0031] For example, the first pair of inertia blocks 6 is arranged at a first radius close to the rim 3, and the second pair of inertia blocks 6' is arranged at a second radius close to the hub 2 of the balance wheel. These inertia blocks 6' close to the hub 2 of the balance wheel are for precise adjustment.

[0032] Similarly, the first pair of inertia blocks 6 is heavier than the second pair of inertia blocks 6', or vice versa. For this purpose, various materials can be used to produce the inertia blocks 6, 6'. For example, the inertia block 6 is made of gold or a gold alloy such as 18K 3N gold, and the inertia block 6' is made of titanium or a titanium alloy such as grade 5 titanium (alloy).

[0033] The inertia blocks 6, 6' include a head 61 in the form of a disc and an optional cylindrical foot 62.

[0034] Advantageously, the shape of the slot 7 is complementary to the shape of the head 61 or the foot 62 of the inertial blocks 6, 6'. This embodiment is particularly advantageous because it makes it possible to limit the thickness of the balance wheel 1 after the inertial blocks 6, 6' have been mounted on the balance wheel 1.

[0035] During the mounting of the inertial blocks 6, 6' into the slot 7, under the elastic action of the elastic arms 5, the inertial blocks 6, 6' are clamped in the slot 7 and are held in their positions by friction.

[0036] The adjustment inertial blocks 6, 6' are provided with slots 63 for adjusting the angular position of the inertial blocks by means of a tool that mates with the slots 63, the tool mating with the slots 63 so as to transmit a torque about the axis of rotation of the inertial blocks 6, 6'. According to Figure 1 the embodiment shown, each inertial block 6, 6' has an uneven portion 64 on the disc forming the head 61.

[0037] Obviously, those skilled in the art will know how to modify the balance wheel 1 and mount any other type of inertial blocks 6, 6' so as to be able to adjust the inertia of the balance wheel 1.

[0038] Thus, this configuration makes it possible to adjust the balance wheel simply and quickly. First, the larger and / or heavier inertial blocks make it possible to perform a basic adjustment, and second, the smaller and / or lighter inertial blocks make it possible to perform a fine adjustment.

[0039] The invention also relates to a timepiece movement and a timepiece equipped with a balance wheel according to the invention.

[0040] Thanks to these different aspects of the invention, we obtain a compact balance wheel for adjusting the position of the inertial blocks, which is easy to manufacture and inexpensive.

[0041] Of course, the invention is not limited to the examples shown, and various variations and modifications will be readily conceivable to those skilled in the art.

Claims

1. A balance wheel (1) for a watch movement, said balance wheel (1) comprising a rigid part which includes a hub (2) defining the pivot axis (A) of the balance wheel (1), a rim (3), and four arms (4) connecting the rim (3) to the hub (2), and said balance wheel (1) comprising four slots (7) for receiving inertia blocks (6, 6') and holding the inertia blocks (6, 6') in place, each slot (7) being bounded on the one hand by an arm (4) and on the other hand by an elastic arm (5), said elastic arm (5) including a first end (5B) integral with the arm (4) and a second distal end (5A) free with respect to the hub (2), the arm (4), and the rim (3). It is characterized in that, The balance wheel (1) comprises two pairs of inertia blocks (6, 6'), each pair of inertia blocks (6, 6') having different masses to ensure different adjustment capabilities, the first pair of inertia blocks (6) being for basic adjustment and the second pair of inertia blocks (6') being for precise adjustment.

2. The balance wheel (1) according to claim 1, characterized in that, Each pair of inertia blocks (6, 6') is relatively disposed in the slots (7) with respect to the pivot axis (A) of the balance wheel (1).

3. The balance wheel (1) according to claim 1 or 2, characterized in that, Each pair of inertia blocks (6, 6') has different dimensions, the first pair of inertia blocks (6) being larger than the second pair of inertia blocks (6'), or the second pair of inertia blocks (6') being larger than the first pair of inertia blocks (6).

4. The balance wheel (1) according to claim 1 or 2, characterized in that, The first pair of inertia blocks (6) is heavier than the second pair of inertia blocks (6'), or the second pair of inertia blocks (6') is heavier than the first pair of inertia blocks (6).

5. The balance wheel (1) according to claim 1 or 2, characterized in that, The two pairs of inertia blocks (6, 6') are made of different materials.

6. The balance wheel (1) according to claim 1 or 2, characterized in that, The first pair of inertia blocks (6) and the second pair of inertia blocks (6') are disposed at different radii of the balance wheel.

7. The balance wheel (1) according to claim 6, characterized in that, The first pair of inertia blocks (6) is disposed at a first radius close to the rim (3), and the second pair of inertia blocks (6') is disposed at a second radius close to the hub (2) of the balance wheel.

8. The balance wheel (1) according to claim 1 or 2, characterized in that, The arms (4), the rim (3), and the hub (2) form a single-piece element.

9. A watch movement, said watch movement comprising a balance wheel (1) according to any one of claims 1 to 8.

10. A watch, said watch comprising a watch movement according to claim 9.

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