Watch movement with means for setting frequency of mechanical resonator

Abstract

The watch movement comprises a mechanical resonator composed of a balance wheel and a balance spring; means for setting the oscillation frequency of the mechanical resonator; and a mechanism for setting a guide mark on the mechanical resonator. The moving member of the setting device includes a mechanism for attaching the outer end portion of the hairspring and a mechanism for defining the effective length of the hairspring. The mechanism for changing the effective length of the hairspring includes a first gear carried by the moving member and a first tooth disposed along the outer end portion of the hairspring, the first gear meshing with the first tooth. The fastening mechanism retains the outer end portion by friction so that the first gear can drive the outer end portion via the first teeth and thus change the effective length of the hairspring. The first gear is in meshing relationship with a second gear that is integral with the resonator support such that when the outer end portion undergoes angular displacement in a selected direction relative to the moving member, the moving member is simultaneously angularly displaced by a corresponding angular distance in an opposite direction.

Description

Technical Field

[0001] The invention relates to a watch movement comprising a mechanical resonator and a device for setting the frequency of the resonator. The invention also relates to a device for setting the guide markings of an escapement associated with the mechanical resonator.

[0002] In particular, the invention relates to a device for setting the frequency of a resonator of a mechanical watch, which device does not affect the previously set guidance markings of the “balance and anchor” system. Background Art

[0003] Patent application BE 483992A describes various embodiments of a device for setting the frequency of a balance-spring forming a resonator of a mechanical watch. With reference to Figures 50 to 54, this document describes such a setting device having the advantage of being able to set the frequency of the resonator from the outside of the case, which is arranged so that the user can set the frequency in this way. The setting device comprises a complex system for correcting the frequency of the mechanical resonator while maintaining the "balance and anchor" system on the guide marks. The setting device is complex. First of all, the setting device comprises a clamp which firmly holds the outer ring of the balance spring at a given angular position on a support, called a "sector", which rotates around the axis of rotation of the balance, this clamping of the outer ring defining the effective length of the balance spring and therefore the oscillation frequency of the balance-spring. The terminal ring is clamped by a slide arranged in the case, which comprises a protruding internal part arranged so as to be able to act on the elastic arm of the clamp. The slide can be actuated substantially tangentially with respect to the axis of rotation of the balance wheel by means of an actuating member on the slide accessible from the outside of the case. The elastic arms are configured so that, in a first angular position of the slide, the slide presses laterally against the elastic arms so as to clamp the outer ring and close the access opening to the setting wheel machined in the case, and so that, in a second angular position, the slide releases the access opening while ceasing to exert a lateral force on the elastic arms so that the outer ring is no longer held by the clamp. The setting device also comprises a column mounted on a second elastic arm of the support and two mutually meshing wheels, each wheel having a spiral cam. The cam of the first wheel presses against the second elastic arm so that it defines the angular position of the column and the angular distance from the clamp. The cam of the second wheel presses against a third spiral cam, which is fixed but whose angular position can be set by the watchmaker when setting the initial guide mark, and the cam of the second wheel is held against the fixed cam by an elastic mechanism for actuating the rotation of the support.

[0004] To set the resonator frequency, the second wheel can be actuated with the aid of a tool when the slide is in its second angular position and the clamp has released the outer coil of the balance spring. This actuation causes the first wheel and its cam to rotate, causing the second elastic arm to move, thus changing the angular position of the post and therefore the angular distance between this post and the clamp. As a result, once the clamp is closed, the effective distance changes, and therefore also the effective length of the balance spring and thus the oscillation frequency. The following is an interesting feature of this complex setting device: turning the second wheel not only changes the angular position of the post and therefore the effective length of the balance spring, but also causes the support to move angularly towards the post in the opposite direction and by substantially the same angular distance, so that the guide mark initially set is not affected, but remains unchanged.

[0005] The setting device described above is complex and has many disadvantages. Firstly, the setting device consists of a large number of parts that must be adjusted. Machining certain parts is complicated, as is assembling the setting device. Furthermore, a significant problem is that the oscillation frequency cannot be set once the watch movement is completed, but can only be set when the watch movement is already mounted in the watch case, and then only through an access opening provided in the side portion of the watch case. A major problem is that the setting device comprises a part mounted on the watch case and which is necessary whenever the frequency needs to be set. Furthermore, the setting device requires a number of elastic parts, namely the hairspring and the two elastically deformable arms, which must be correctly dimensioned and which may show some fatigue damage over time. Finally, the ends of the outer ring of the hairspring are usually held in the column by lateral screws or more often by adhesive bonding; these fastening mechanisms produce stresses on the ends of the hairspring, which affect the accuracy of the frequency setting. Summary of the invention

[0006] The object of the present invention is to solve the problems of the prior art mentioned in the technical background by providing a watch movement equipped with a mechanical resonator and a device for setting the frequency of the mechanical resonator, the mechanical resonator consisting of a balance wheel-hairspring, the device being uncomplicated, reliable and independent of the case and being able to effectively set the frequency without changing the initial setting of the guide marks.

[0007] To this end, the present invention relates to a watch movement, comprising:

[0008] - a mechanical resonator consisting of a balance wheel rotatably mounted in a support and of a balance spring,

[0009] - an escapement comprising an anchor arranged to oscillate synchronously with the balance, and

[0010] - means for setting the oscillation frequency of the mechanical resonator, called setting means,

[0011] The setting device comprises a mobile part, called mobile part, rotating about the axis of rotation of the balance wheel, the mobile part comprising means for attaching the outer end portion of the hairspring, called fastening means, and means for defining the effective length of the hairspring, called limiting means, which define the end point of the effective part of the hairspring at a fixed point on the mobile part once the hairspring has been attached to the mobile part by the fastening means. The setting device also comprises means for varying the effective length of the hairspring, called varying means, making it possible to set the oscillation frequency by an angular displacement of the outer end portion relative to the mobile part and therefore relative to said fixed point on the mobile part relative to said axis of rotation in a chosen direction, the setting of the oscillation frequency being combined with a rotation of the mobile part over an angular distance substantially corresponding to said angular displacement and in a direction opposite to the chosen direction.

[0012] The watch movement also includes a mechanism for setting the guide mark of the mechanical resonator relative to the anchor, called the guide mark setting mechanism. The changing mechanism includes a first gear carried by the mobile part and a first tooth arranged along the outer end portion of the hairspring, the first tooth meshing with a first gear capable of rotating to perform an angular displacement, and the fastening mechanism holds the outer end portion by friction so that the first gear can drive the outer end portion via the first tooth, thereby causing the outer end portion to be angularly displaced relative to the mobile part and the limiting mechanism in order to change the effective length of the hairspring. Finally, the first gear is in meshing relationship with the second tooth, and the second tooth is integral with the resonator support, so that when the outer end portion undergoes the angular displacement in a selected direction relative to the mobile part, the mobile part simultaneously causes the angular distance to be angularly displaced in the opposite direction. Therefore, no angular displacement of the outer end portion occurs, and the previously set guide mark remains unchanged.

[0013] The setting device of the invention does not require a hairspring. In addition, it is sufficient to provide a mechanism that actuates the first gear or mobile part to set the resonator frequency without misaligning the guide mark set in advance. Although this setting device capable of setting the oscillation frequency while automatically maintaining the guide mark set in the preliminary step can be provided for a watch, once the watch has been completely installed, the setting device is independent of the watch case, so that such a watch movement can also be installed in a watch case that cannot be set from the outside of the watch case. The device may in fact appear complicated in terms of the outer end portion of the hairspring including teeth. Such teeth can be formed in the following part, which is initially separated from the hairspring and is combined or welded or fastened to the end of the outer ring of a traditional hairspring by any other means. Since today's hairsprings are increasingly made of silicon and use micromachining techniques borrowed from the field of microtechnology, the realization of the outer end portion of the hairspring with lateral teeth (in other words, the cutting profile of the hairspring with teeth) does not cause particular problems. This also applies to hairsprings made of glass or similar materials. It should be noted that the guide mark may be set simply by the initial positioning of the first tooth relative to the first gear wheel with the moving part in a given initial position. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention will now be described in more detail with reference to the accompanying drawings, given by way of non-limiting examples, in which:

[0015] - Figure 1 is a perspective top view of an embodiment of a watch movement according to the present invention, Figure 1 A watch movement assembly is shown including the setting device and the outer end portion of the balance spring.

[0016] - Figure 2 yes Figure 1 A top view of the components of a watch movement shown in , in which the upper plate is shown as transparent and its outline is shown as a dotted line (except for its teeth).

[0017] - Figure 3 yes Figure 1 A perspective top view of a watch movement assembly in which the upper plate has been removed from the watch movement assembly.

[0018] - Figure 4 yes Figure 1 A partial perspective view of the components shown in and the outer end portion of the balance spring as seen from below.

[0019] - Figure 5A and 5B yes Figure 1The assembly shown in and a partial view from below of the outer end portion of the balance spring, with the mobile part in two different positions corresponding to two different effective lengths of the balance spring. DETAILED DESCRIPTION

[0020] With reference to the accompanying drawings, the following is a description of a watch movement according to the present invention.

[0021] Watch movement 2 includes:

[0022] a mechanical resonator consisting of a balance wheel rotatably mounted in a support (only the balance stem 14 forming this support is shown in the figure) and a balance spring 6 (only a part of the outer ring 7 and the outer end portion 8 of the balance spring are shown in the figure),

[0023] an escapement comprising an anchor arranged to oscillate synchronously with the balance (this escapement is not shown in the figures, in particular a traditional watch escapement with an anchor of Swiss type), and

[0024] - Means 4 for setting the frequency of the mechanical resonator, called "setting means".

[0025] In particular, the balance is a typical balance with a bridge having a pin acting as a periodic coupling member between the anchor and the oscillating balance, thereby causing a reciprocating movement of the anchor, which thus oscillates synchronously with the balance. The setting device 4 comprises a mobile part 16 rotating about the axis of rotation 50 of the balance, referred to as "mobile part", the function of which is to tighten the outer end portion 8 of the balance spring 6 and to define the effective length of this balance spring. Moreover, the mobile part 16 and the outer end portion 8 are arranged so that the mechanical resonator guide mark can be set relative to the escapement anchor. Moreover, as will be more clearly understood below, the mobile part 16 is arranged so that once the resonator and the setting device 4 have been installed in the watch movement 2, a variation in the effective length of the balance spring is obtained in order to set the oscillation frequency of the mechanical resonator while maintaining the angular position of the outer end portion determined when it was tightened, and thus maintaining a stable angular position of the balance-spring when at rest, so as not to lose the guide mark previously set. Thus, in particular, the effective length of the balance spring is varied while maintaining the correct alignment of the balance pin at rest, ie radially on the axes of rotation of the balance and of the anchor.

[0026] Thus, in general, mobile part 16 comprises: means for attaching outer end portion 8 of balance spring 6, called “fastening means”; and means for limiting the effective length of balance spring 6, called “limiting means”, which, once the balance spring has been fastened to the mobile part by the fastening means, is located at a fixed point P on mobile part 16. F The end point P on the effective part of the balance spring 6 is defined at EThe setting device 4 also comprises a mechanism for varying the effective length of the balance spring, called “varying mechanism”, making it possible to set the oscillation frequency by adjusting the position of the outer end portion 8 relative to the mobile part 16 and therefore relative to said fixed point F on this mobile part. P An angular displacement in a selected direction relative to the axis of rotation 50 is combined with a rotation of the mobile part about said axis of rotation over an angular distance substantially corresponding to said angular displacement and in a direction opposite to the selected direction (see Figure 5A and 5B ). The watch movement also comprises a mechanism for setting the guide mark of the mechanical resonator relative to the escapement anchor in a preliminary step, called "guide mark setting mechanism". This preliminary step is a step that takes place when the resonator is installed in the watch movement, or when the watch movement is serviced by a watchmaker.

[0027] According to the invention, the change mechanism is composed of a first gear 22 carried by the bridge 18 on the mobile part 16 and a first tooth 10 arranged along the outer end portion 8 of the balance spring, which first tooth meshes with a first gear wheel that can rotate to perform the above-mentioned angular displacement. Preferably, the balance spring is made of silicon or glass and is obtained using micromachining techniques. Therefore, when manufacturing the balance spring 6, the first tooth can be easily obtained.

[0028] According to the invention, the fastening means retain said outer end portion 8 by friction so as to allow the first toothed wheel 22 to drive it via the first toothing 10 and thus to cause an angular displacement of the outer end portion relative to the mobile part 16 and said limiting means so as to vary the effective length of the balance spring 6. The first toothed wheel 22 is in meshing relationship with a fixed toothing 30 comprising an upper plate 28 fastened to the resonator support and more generally to a second toothing 30 integral with this support, so that when the outer end portion undergoes said angular displacement in a chosen direction relative to the mobile part 16, this mobile part is simultaneously angularly displaced in the opposite direction by said angular distance.

[0029] In an advantageous variant shown in the figures, the tightening mechanism also comprises a first eccentric 32 and a second eccentric 33 arranged respectively on either side of the outer end portion 8 of the balance spring 6. These first and second eccentrics can each be turned by a tool so that when the balance spring is mounted in the movement 2, when the balance spring 6 is in a non-constrained state and therefore in its own rest position, the first and second eccentrics contact respectively the first and second side faces of the outer end portion 8 so that, for any oscillation frequency setting within the useful range, the portion of the outer end portion situated between the first eccentric 32 and the second eccentric 33 has a spatial positioning corresponding to that of the rest position of the balance spring itself and this portion, after tightening of the outer end portion, can maintain this spatial positioning when the mechanical resonator oscillates. This feature is very advantageous for ensuring that the oscillation of the balance spring is properly centered on the axis of rotation 50 when the watch movement ticks. This increases the precision of the watch movement. The second eccentric 33 is positioned facing the wheel 22 situated on the other side of the second eccentric relative to the outer end portion 8. The second eccentric 33 also holds the first tooth in the first gear 22, thus ensuring that they mesh. The radial positioning of the outer end portion of the balance spring 6, the radial positioning of the first gear wheel and the various components involved in the first gear wheel are preferably machined with sufficiently low tolerances so that, in the rest position of the balance spring itself (balance spring in a non-constrained state), the first tooth 10 is in meshing relationship with the first gear wheel 22 with a certain amount of play. In fact, if this were not the case, it would not be possible to have a meshing between the first gear wheel and the first tooth of the balance spring while maintaining the portion of the outer end portion 8 located between the first eccentric 32 and the second eccentric 33 in a spatial position corresponding to that of the rest position of the balance spring itself. It should be noted that the first and second eccentrics advantageously have a circular groove in which the outer end portion 8 is placed. Such a groove enables the outer end portion to be axially positioned.

[0030] The means for limiting the effective length of the balance spring 6 comprise a first eccentric 32 against which the first portion 9a of the outer end portion 8 is pressed. The contact point at which this first portion 9a is pressed against the first eccentric defines the end of the effective portion of the balance spring and therefore defines the end point P of its effective length. E The end point is located at a contact point that is fixed relative to the moving part so that the end point is always located at a specific fixed point P F At, that is, at an invariant point on the moving part.

[0031] The guide mark setting mechanism is composed of the following: a first tooth 10 on the hairspring 6, which is arranged along the middle part of the outer end part 8 of the hairspring; and a first gear 22, when the mobile part 16 is in a given initial angular position, the guide mark is set by the initial angular positioning of the first tooth relative to the first gear, and the initial angular position can be any position in the angular stroke of the mobile part, but preferably is basically in the middle of the angular stroke.

[0032] In the variant described, the tightening means comprise a third eccentric 34 arranged on the same side of the outer end portion of the balance spring as the first eccentric 32, the second eccentric 33 being located between the first and third eccentrics along the outer end portion, the first eccentric 32 being positioned relative to the second eccentric towards the outer ring 7 of the balance spring 6. The third eccentric is arranged so that it can be turned by a tool to exert a third transverse force F3 on the outer end portion 8, so that the first and second eccentrics react by exerting a first transverse force F1 and a second transverse force F2 respectively on the outer end portion 8, thereby keeping the outer end portion in place by the friction between the outer end portion and the first, second and third eccentrics without the first gear 22 rotating.

[0033] According to an advantageous feature, the first transverse force F1 can be of such magnitude and the first portion 9a of the outer end portion 8, positioned facing the first eccentric 32, has a selected stiffness so that it can remain in contact with the first eccentric when the mechanical resonator oscillates. Thus, once set, the effective length of the balance spring remains constant when the resonator oscillates, regardless of the fact that the first portion 9a is in contact only on one side with the mechanism for defining the effective length of the balance spring, which mechanism consists only of the eccentric 32. In particular, the stiffness of the first portion 9a is chosen so that the oscillation frequency can be set accurately.

[0034] According to a particular feature of the fastening means, the outer end portion 8 has a terminal portion 9b located after the first tooth 10, which occupies the middle part of this outer end portion, the terminal portion 9b being more flexible than the first portion 9a and being positioned facing the third eccentric 34, which third eccentric can exert a third lateral force F3 on this terminal portion. Preferably, the width of the terminal portion 9b increases towards its free end, so that the third lateral force F3 remains substantially constant for any frequency setting and therefore for any effective length within the expected setting range.

[0035] In the embodiment described, mobile part 16 comprises a second gear wheel 24 mounted coaxially with first gear wheel 22, these first and second gear wheels being fastened to the same arbour 20 so that they rotate together. Second gear wheel 24 meshes with fixed teeth 30 of an upper plate 28 attached to balance staff 14 forming part of the support of the mechanical resonator.

[0036] According to a particular variant, mobile part 16 comprises a third toothing 38 carried by arm 18a of bridge 18, and mechanical movement 2 comprises means for rotating the mobile part around said axis of rotation 50 via the third toothing. Bridge 18 also comprises two elastic arms 18b and 18c forming a split ring around the support of anti-seismic bearing 46, which thus guides mobile part 16 in rotation. The drive means are arranged so that they can be actuated from the lateral periphery of the movement to rotate mobile part 16, thereby producing a variation in the effective length of balance spring 6 from this lateral periphery, via first gear 22 and second gear 24. The drive means comprise a third gear 40 meshing with an Archimedean screw 42 having an end 42a accessible from the lateral periphery of the mechanical movement and having a non-cylindrical coupling portion designed to allow it to be coupled to a member for actuating it. It should be noted that the upper clamping plate 28 has a projection 28a that holds the Archimedean screw in a constant longitudinal position, so that when the Archimedean screw rotates, the gear 40 is driven in rotation even in the absence of any longitudinal pressure exerted on the Archimedean screw.

[0037] The invention also relates to a watch comprising a mechanical movement according to the invention. The watch comprises a case (not shown) housing the mechanical movement 2 and arranged so that the drive means of the moving parts can be actuated by the aforementioned actuating member (not shown) which can be operated from the outside of the watch.

Claims

1. A watch movement (2), comprising: - a mechanical resonator consisting of a balance spring (6) and a balance wheel rotatably mounted in a support; - an escapement comprising an anchor arranged to oscillate synchronously with the balance; as well as - means (4) for setting the oscillation frequency of the mechanical resonator, referred to as setting means; The setting device (4) comprises a mobile part (16) rotating about the axis of rotation (50) of the balance wheel, called a mobile part, comprising means for attaching the outer end portion (8) of the balance spring, called a fastening means, and means for limiting the effective length of the balance spring, called a limiting means, which, once the balance spring has been attached to the mobile part by the fastening means, is fixed at a fixed point (P) on the mobile part (16). F ) defines the end point (P) of the effective part of the hairspring E ), the setting device also includes a mechanism for changing the effective length of the hairspring (6), so that the oscillation frequency can be set by an angular displacement of the outer end portion (8) relative to the mobile part and therefore relative to the fixed point on the mobile part relative to the rotation axis and in a selected direction, the setting of the oscillation frequency being combined with a rotation of the mobile part (16) over an angular distance substantially corresponding to the angular displacement and in a direction opposite to the selected direction; the watch movement also includes a mechanism for setting the guide mark of the mechanical resonator relative to the anchor, called the guide mark setting mechanism; characterized in that the changing mechanism includes a first gear (22) carried by the mobile part and a gear along the The invention relates to a first tooth (10) arranged on the outer end portion of the hairspring, the first gear wheel meshing with the first tooth and the first tooth being rotatable to perform the angular displacement, the fastening mechanism holding the outer end portion (8) by friction so that the first gear wheel can drive the outer end portion via the first tooth and thus angularly displace the outer end portion relative to the moving part and the limiting mechanism so as to change the effective length of the hairspring; and characterized in that the first gear wheel (22) is in meshing relationship with a second tooth (30) which is integral with the resonator support so that when the outer end portion undergoes the angular displacement in a selected direction relative to the moving part, the moving part is simultaneously angularly displaced in the opposite direction by the angular distance.

2. The watch movement according to claim 1, characterized in that: The hairspring (6) is made of silicon or glass and is obtained by micro-machining technology.

3. The watch movement according to claim 1 or 2, characterized in that: The fastening mechanism comprises a first eccentric member (32) and a second eccentric member (33), the first eccentric member and the second eccentric member being arranged on both sides of the outer end portion (8) of the hairspring respectively and being rotatable by a tool so that when the hairspring (6) is mounted in the watch movement, the first eccentric member and the second eccentric member are in contact with the first side surface and the second side surface of the outer end portion (8) respectively, while the hairspring is in a non-constrained and therefore in its own static position, so that for any oscillation frequency setting within a useful range, the portion of the outer end portion between the first eccentric member and the second eccentric member (32, 33) has a spatial positioning substantially corresponding to the spatial positioning of the static position of the hairspring itself, and the fastening mechanism, once fastened, maintains the spatial positioning to the portion of the outer end portion, the first eccentric member (32) constituting the limiting mechanism.

4. The watch movement according to claim 3, characterized in that: The fastening mechanism comprises a third eccentric member (34) which is arranged on the same side of the outer end portion (8) of the hairspring as the first eccentric member (32), the second eccentric member (33) being located between the first eccentric member and the third eccentric member along the outer end portion, the first eccentric member being positioned relative to the second eccentric member toward the outer ring (7) of the hairspring, and the third eccentric member (34) being arranged so that it can be rotated by a tool to exert a third lateral force on the outer end portion (8), so that the first eccentric member and the second eccentric member react by exerting a first lateral force and a second lateral force on the outer end portion respectively, the outer end portion being thereby held in place by friction between the outer end portion and the first eccentric member, the second eccentric member and the third eccentric member when the first gear does not rotate.

5. The watch movement according to claim 4, characterized in that: The first transverse force may have such a magnitude and a first portion of the outer end portion, located facing the first eccentric, has a selected stiffness such that the first portion can remain in contact with the first eccentric when the mechanical resonator oscillates.

6. The watch movement according to claim 5, characterized in that: The stiffness is selected such that the oscillation frequency can be set precisely.

7. The watch movement according to claim 5 or 6, characterized in that: The outer end portion has a terminal portion located behind the first tooth, the terminal portion being more flexible than the first portion and being located facing the third eccentric, the third eccentric being able to exert the third lateral force on the terminal portion.

8. A watch movement according to any one of the preceding claims, characterised in that The guide mark setting mechanism is composed of a first tooth of the hairspring and the first gear, and the guide mark is set by initial positioning of the first tooth relative to the first gear when the moving part is at a given angular position.

9. A watch movement according to any one of the preceding claims, characterised in that The moving part (16) comprises a second gear (24) mounted coaxially with the first gear (22), the first gear and the second gear being arranged on the same spindle (20) so that they rotate together, the second gear (24) meshing with the second tooth (30).

10. A watch movement according to any one of the preceding claims, characterised in that The mobile part (16) comprises a third tooth (38), and the movement comprises means for rotating the mobile part around the rotation axis (50) via the second tooth (30); and the drive means are arranged so that it can be actuated from a lateral periphery of the movement to rotate the mobile part (16), thereby producing a change in the effective length of the balance spring from the lateral periphery via the first gear and the second gear.

11. The watch movement according to claim 10, characterized in that: The drive device comprises an Archimedean screw (42) one end of which is accessible from the lateral periphery of the movement and which has a non-cylindrical coupling portion to enable the Archimedean screw to be coupled to a member for actuating the Archimedean screw.

12. A watch comprising the movement according to claim 10 or 11, characterized in that: The watch comprises a case housing the movement (2) and is arranged so that the drive means of the mobile part (16) can be actuated by an actuating member which can be operated from the outside of the watch.

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