Transmission mechanism for watch movements

Abstract

To provide a timepiece transmission mechanism having a smaller and delicately simplified alternative structure compared with a conventional conversion mechanism.SOLUTION: A timepiece transmission mechanism 1 comprises a transmission wheel comprising: a driving plate, configured to pivot about a first rotation axis in response to movement of a driving wheel; and a link mechanism 2 having a flexible portion and supporting a unidirectional transmission mechanism arranged to cooperate with an output wheel 4 configured to drive a driven wheel when the driving wheel is displaced in a first displacement direction. The link mechanism comprises: a base secured to the driving plate and arranged so as to cause rotational movement about the first fixed rotation axis, in response to movements of the driving wheel: and a first arm extending from the base and supporting the unidirectional transmission mechanism at a distal end of the first arm 8. The flexible portion is arranged on the first arm.SELECTED DRAWING: Figure 3a

Description

[Technical Field]

[0001] The present invention relates to a transmission mechanism for a timepiece movement configured to transmit the movement of a drive wheel of the timepiece movement to a driven wheel, and in particular to a transmission mechanism comprising a transmission wheel having a drive plate configured to be kinematically linked to the drive wheel and to pivot about a first fixed axis of rotation in response to movement of the drive wheel, and a linkage supporting a one-way transmission mechanism having a flexible portion and arranged to cooperate with a drive surface of an output wheel configured to link to the driven wheel to drive the drive surface when the drive wheel is displaced in a first displacement direction.

[0002] According to a preferred embodiment, the invention relates to an automatic winding mechanism comprising a transmission mechanism of this type, which creates a link between the winding mass and the mechanical energy storage device.

[0003] The invention also relates to a clock movement having such a transmission mechanism and to a clock equipped with such a clock movement. [Background technology]

[0004] Timepiece mechanisms of this type are already known in the prior art, especially with regard to automatic winding mechanisms.

[0005] For example, EP 3203326 (Patent Document 1) illustrates and describes a transmission mechanism that meets the above-mentioned characteristics. More specifically, the transmission mechanism is configured to convert the bidirectional rotational movement of the winding weight into a unidirectional movement that ensures the winding of the barrel spring. For this purpose, the mechanism comprises a first rotating wheel configured to be driven by the movement of the winding weight in one direction or another. The first wheel supports a transmission disc. The transmission disc is off-center with respect to the rotation axis of the first wheel and is configured to drive the transmission mechanism by a circular translational movement. The transmission mechanism, in cooperation with a clutch mechanism, ensures the barrel spring is energized. The clutch mechanism is arranged to enable the unidirectional rotational drive of an output wheel configured to link to the end of the barrel spring. For this purpose, the transmission mechanism supports two drive surfaces that may have an over-center link with the clutch mechanism, each drive surface associated with a given direction of rotation. For each rotational direction of the winding weight, the drive surface is alternately moved in a reciprocating motion toward and away from the clutch mechanism by the circular translational motion of the transmission mechanism, and thus the drive surface alternately cooperates with the clutch mechanism to rotationally drive the clutch mechanism in exactly the same rotational direction.

[0006] Such a structure requires high precision in manufacturing and in the alignment of the various components involved to ensure that the trajectory of the drive face effectively achieves the desired over-center link of the clutch mechanism. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent No. 3203326 Summary of the Invention [Problem to be solved by the invention]

[0008] One of the main objectives of the present invention is to propose a timepiece transmission mechanism having an alternative structure that is more compact and subtly simplified compared to the conversion mechanisms described above.

[0009] To this end, the present invention relates more particularly to a transmission mechanism of the above type, characterized in that the link mechanism comprises a base fixed to the drive plate and arranged to exhibit rotational movement about a first fixed axis of rotation in response to movement of the drive wheel, and that the link mechanism comprises a first arm extending from the base and supporting a one-way transmission mechanism at its distal end, the flexible portion being arranged on the arm.

[0010] These features allow the arms of the linkage, including the flexible portions of the arms, to be shaped and dimensioned to ensure good one-way drive of the output wheel by the one-way transmission mechanism while driving the linkage according to a simple rotary motion.

[0011] Preferably, the arm supports at least one additional flexible portion.

[0012] This feature gives the manufacturer of the mechanism greater freedom in choosing the shape of the arm.

[0013] Generally, where the output wheel is configured to pivot about a second fixed axis of rotation, the distal end of the arm may be fixed to a radial guide arm that is rotatable relative to the output wheel but is also arranged to pivot about the second fixed axis of rotation.

[0014] In this case, the one-way transmission mechanism may be arranged at the distal end so as to be pivotable relative to the distal end about the third movable rotation axis, and may support a contact surface arranged to have an over-center relationship with the drive surface of the output wheel, such that the contact surface drives the drive surface in a first relative rotation direction between the radial guide arm and the output wheel, and the contact surface may be displaced in a direction opposite to the relative rotation direction between the radial guide arm and the output wheel without driving the drive surface.

[0015] It is then advantageously possible to provide an arm of the linkage or a radial guide arm which supports an elastic return mechanism arranged to act on the one-way transmission mechanism and tend to place the one-way transmission mechanism in a predefined rest position.

[0016] Generally, the linkage mechanism supports a second arm having similar structural characteristics to the first arm and supporting an additional one-way transmission mechanism, the second arm being arranged to drive the drive surface of the output wheel when the drive wheel is displaced in a second displacement direction opposite to the first displacement direction.

[0017] Given that an arm supporting at least one flexible portion is associated with each one-way transmission mechanism, such a structure is less restrictive in terms of component manufacturing and placement than the prior art mechanisms described above.

[0018] In this case, advantageously, the first arm and the second arm may extend in respective general directions that are inclined relative to each other by an angle of between 70° and 110°.

[0019] According to a preferred variant embodiment, the invention relates to an automatic winding mechanism comprising a transmission mechanism that fully or partly complies with the above-mentioned characteristics, as well as comprising a winding weight adapted to be pivotally mounted on a frame element of a timepiece movement and having a kinematic link with the drive plate.

[0020] In this case, the winding weight may preferably be arranged to exhibit an oscillatory movement of low amplitude, preferably less than 20°, more preferably less than 10°.

[0021] The present invention generally relates to a timepiece movement equipped with a transmission mechanism conforming to the above characteristics, whether or not the transmission mechanism is integrated into an automatic winding mechanism, and to a timepiece equipped with such a timepiece movement.

[0022] Other characteristics and advantages of the invention will appear more clearly on reading the following detailed description of preferred embodiments, given with reference to the accompanying drawings, given as non-limiting examples, in which: [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram of a part of a transmission mechanism according to the present invention, illustrating the general operating principle of the transmission mechanism; [Figure 2] 1 is a perspective view showing a simplified portion of a transmission mechanism according to a preferred embodiment of the present invention, viewed from a first surface side. [Figure 3a] 3 is a front view showing the transmission mechanism of FIG. 2 when driven to rotate in a clockwise direction, as viewed from the second surface side. FIG. [Figure 3b] 3a, showing the transmission mechanism of FIG. 2 when driven in rotation in the counterclockwise direction; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] In the following detailed description, a timepiece transmission mechanism according to a preferred embodiment of the invention will be presented and described by way of illustrative and non-limiting example. More particularly, according to the embodiment shown and described, the transmission mechanism is configured to be integrated into the automatic winding mechanism of a timepiece, although it will be clear to those skilled in the art that the transmission mechanism according to the invention can be implemented in relation to other types of timepiece mechanisms without departing from the scope of the invention as defined in the claims.

[0025] FIG. 1 is a schematic diagram of a part of a transmission mechanism 1 according to the invention, illustrating the general operating principle of the transmission mechanism.

[0026] Generally, the transmission mechanism 1 according to the present invention is configured to convert the bidirectional rotational movement of a drive wheel (not shown) into the unidirectional rotational movement of a driven wheel. For this purpose, the transmission mechanism 1 in particular comprises a link mechanism 2. The link mechanism 2 is configured to be bidirectionally rotationally driven by the movement of the drive wheel and to drive an output wheel 4 according to the unidirectional rotational movement.

[0027] When the transmission mechanism 1 according to the invention is incorporated into an automatic winding mechanism, it can be advantageously arranged so that the bidirectional rotational motion of a winding weight (not shown) is converted into unidirectional rotational motion before the unidirectional rotational motion is transmitted to a mechanical energy storage mechanism, which converts the bidirectional rotational motion of a winding weight (not shown) into unidirectional rotational motion before it is stored in mechanical energy, typically in a barrel spring (not shown).

[0028] Returning to the schematic illustration of Figure 1, it is clear that the linkage 1 comprises a base 6 which is adapted to be mounted for rotation around a frame element of the timepiece movement.

[0029] The base 6 supports two arms 8, 10, which extend in general directions inclined relative to one another towards a region near the circumference of the output wheel 4. In the case of an automatic winding mechanism, the output wheel 4 is configured to be kinematically linked to a mechanical energy storage mechanism.

[0030] Each arm 8, 10 carries at its distal end a support 14, 16 to which a one-way transmission mechanism 18, 20 having a generally circular wheel shape is mounted for rotation about an axis of rotation 22, 24. Finally, in the exemplary embodiment, radial guide arms 26, 28 are provided to link each support 14, 16 to the axis of rotation 30 of the output wheel 4, and thus to maintain the corresponding axis of rotation 22, 24 at a constant distance from the axis of rotation 30.

[0031] It can be seen that each of the rotation axes 22, 24 is slightly offset relative to a radius passing through the rotation axis 30 of the output wheel 4 and the contact point of the corresponding one-way transmission mechanism and output wheel 4. Furthermore, each of the rotation axes 22, 24 is preferably slightly offset from the center of the circumference of the corresponding one-way transmission mechanism, which circumference defines the contact surface with the output wheel 4.

[0032] 1, it is therefore clear that when the one-way transmission mechanism 18 pivots in a clockwise rotational direction, the one-way transmission mechanism 18 will present a radius that is increasingly larger than the radius passing through the rotation axis 30 of the output wheel 4 and the point of contact between the one-way transmission mechanism 18 and the output wheel 4. This situation occurs when the linkage 2 rotates in a clockwise direction as viewed in FIG.

[0033] If the distance between the rotation axis 22 of the one-way transmission mechanism 18 and the circumference of the output wheel 4 is kept constant, after a certain time, i.e., when the radius of the one-way transmission mechanism 18 located between the rotation axis 22 of the one-way transmission mechanism 18 and the point of contact between the rotation axis 22 of the one-way transmission mechanism 18 and the circumference of the output wheel 4, becomes large enough to prevent the one-way transmission mechanism 18 from pivoting freely, the one-way transmission mechanism 18 will pivot, causing an over-center link with the output wheel 4. From that moment on, when the linkage 2 rotates in the same rotation direction (clockwise as viewed in FIG. 1), the significant friction generated between the output wheel 4 and the one-way transmission mechanism 18 will also drive the output wheel 4 to rotate in the same rotation direction, and the one-way transmission mechanism 18 will no longer be able to pivot around the rotation axis 22 of the one-way transmission mechanism 18 due to its part.

[0034] 1, when the link mechanism 2 rotates counterclockwise, the one-way transmission mechanism 18 also rotates counterclockwise. By following this movement, the radius of the one-way transmission mechanism 18, which is located between the rotation axis 22 of the one-way transmission mechanism 18 and the contact point between the circumference of the output wheel 4 and the one-way transmission mechanism 18, tends to become smaller. Therefore, the one-way transmission mechanism 18 can freely rotate relative to the output wheel 4 (again, when in an over-center link state). Therefore, when the link mechanism 2 pivots in the counterclockwise rotation direction, the one-way transmission mechanism 18 does not drive the output wheel 4 to rotate.

[0035] As is clear from Figure 1, the other one-way transmission mechanism 20 is attached to the support 16 of the one-way transmission mechanism 20 in a manner similar to that of the one-way transmission mechanism 18. However, the arms 8 and 10 extend on either side of a line passing through the center of the linkage 2 and the center of the output wheel 4. Therefore, for a given direction of rotation of the linkage 2, the two one-way transmission mechanisms 18 and 20 pivot in opposite rotational directions in cooperation with the circumference of the output wheel 4. As a result, each of the one-way transmission mechanisms 18, 20 is associated with a given direction of rotation of the linkage 2 and has an over-center link with the output wheel 4 in this linkage, thereby driving the output wheel 4 to rotate.

[0036] 1, when the link mechanism 2 rotates clockwise, it drives the one-way transmission mechanism 18 to rotate in the same direction, which tends to place the one-way transmission mechanism 18 in an over-center link with the output wheel 4, driving the output wheel 4 to rotate clockwise. At the same time, the one-way transmission mechanism 20 rotates freely counterclockwise without exerting any special effect on the periphery of the output wheel 4.

[0037] Conversely, when linkage 2 rotates counterclockwise, one-way transmission mechanism 18 freely drives rotation in the same direction relative to output wheel 4. At the same time, one-way transmission mechanism 20 rotates clockwise, which tends to place one-way transmission mechanism 20 in an over-center link with output wheel 4, driving the output wheel in a clockwise rotational direction.

[0038] Therefore, whatever the direction of rotation of the link mechanism 2, the one-way transmission mechanisms 18, 20 alternately drive the output wheel 4 in exactly the same direction.

[0039] It should be noted that a return spring 32 is preferably associated with each one-way transmission mechanism 18, 20 and cooperates with a pin 34 fixed to each one-way transmission mechanism, preventing the orientation of each one-way transmission mechanism from straying too far from the orientation that would result in over-center interaction with the output wheel 4, thus ensuring greater responsiveness of the transmission mechanism according to the invention, particularly when the drive direction of the linkage 2 changes.

[0040] Obviously, the above operating principle can be implemented with a single arm supporting a single one-way transmission mechanism, in which case, when the transmission mechanism is incorporated into, for example, an automatic winding mechanism, only one direction of rotation of the winding weight will contribute to the energy storage mechanism.

[0041] According to a preferred embodiment of the present invention, but in a non-limiting manner, the arms 8, 10 each have two flexible portions 36 between their proximal ends, which are fixed to the base 6 of the linkage 2, and their distal ends, which comprise the corresponding supports 14, 16. The flexible portions 36 are configured to allow the arms 8, 10 to deform when the linkage 2 is rotationally driven, and to ensure that the corresponding one-way transmission mechanisms 18, 20 are properly guided.

[0042] A person skilled in the art will have no particular difficulty in adapting the shape of the arms to specific needs, in particular in varying the number of flexible parts of the arms, without in any way departing from the scope of the invention as defined by the claims.

[0043] If the transmission mechanism comprises two arms 8, 10, the arms may advantageously have an angle of about 70 to 110 degrees between them. However, it is clear that a person skilled in the art can adapt this indication depending on the shape that the arms are ultimately to be manufactured and on the number of flexible parts they contain. In that respect, it should also be noted that the two arms do not necessarily have the same number of flexible parts.

[0044] Figure 2 is a simplified perspective view of a portion of the transmission mechanism 1 according to a preferred embodiment of the present invention from the first side, allowing a better understanding of certain structural details. Furthermore, Figures 3a and 3b are front views of the transmission mechanism 1 of Figure 2 from the second side, respectively, in two different stages of operation.

[0045] According to this embodiment, shown as a non-limiting example, the linkage 2 is associated with a drive plate 40, which has teeth and is fixed to the base 6 so as to rotate, defining a transmission wheel. It is envisaged that the drive plate 40 has a kinematic link with the drive wheel, e.g. a winding weight, via the teeth of the drive plate 40, in order to reliably drive the base 6 and thus the arms 8, 10.

[0046] Alternatively, the drive plate 40 can, of course, be manufactured integrally with the base 6 and / or have other linkage means with the drive wheels without departing from the scope of the present invention. Indeed, other linkage means between the linkage 2 and the drive wheels can be implemented without in any way departing from the scope of the present invention.

[0047] The output wheel 4 has a drive surface defined by the circumference of the first driven wheel 42. The drive surface is frictionally arranged to cooperate with a circumferential contact surface of a one-way transmission mechanism 48, 50 and is fixed to the drive gear 44. The drive gear 44 is envisioned to have a kinematic link with the driven wheel (not shown), such as a barrel spring winding ratchet. The one-way transmission mechanisms 48, 50 are therefore configured to drive the first driven wheel 42 in a single rotational direction, such that the drive gear 44 can drive the driven gear in exactly the same direction and so that the drive gear 44 can drive the driven gear in the same direction regardless of the direction of rotation of the drive wheel. Alternatively, the driven wheel can be driven directly by the output wheel 4.

[0048] It should be noted that the one-way transmission mechanisms 48, 50 have a different shape than that shown in Figure 1. In fact, each of these mechanisms has a pad shape that is slightly asymmetrical relative to its median plane. A close inspection of Figures 3a and 3b reveals that each pad has a slightly larger radius on the left side of its median plane than on the right side.

[0049] The drive plate 40 is positioned to engage with the intermediate link wheel 52. It is envisioned that the intermediate link wheel 52 is rotationally driven by the drive wheel. According to the embodiment shown in Figures 2, 3a and 3b, in a non-limiting manner, the drive wheel is arranged to oscillate slightly around an equilibrium position, so that the intermediate link wheel 52 is driven to exhibit a reciprocating motion similar to the linkage 2.

[0050] FIG. 3a illustrates the operation of transmission mechanism 1 when intermediate link wheel 52 is driven to rotate clockwise. Link mechanism 2 is then driven to rotate counterclockwise, causing the distal ends of arms 8, 10 to move away from base 6 of link mechanism 2. In this case, one-way transmission mechanism 50 pivots in a clockwise rotational direction in cooperation with first driven wheel 42, while mechanism 48 pivots in a counterclockwise rotational direction, as viewed in FIG. 3a. Mechanism 50 now presents a larger radius relative to the direction of first driven wheel 42, while mechanism 48 presents a smaller radius relative to this same wheel 42. As a result, mechanism 50 is over-centered relative to first driven wheel 42, but mechanism 48 is free to rotate without acting on this same wheel 42. This is reflected by the clockwise rotational drive of first driven wheel 42, as viewed in FIG. 3a, as indicated by arrow H.

[0051] FIG. 3b shows the operation of transmission mechanism 1 when intermediate link wheel 52 is driven to rotate counterclockwise. Link mechanism 2 is then driven to rotate clockwise, causing the distal ends of arms 8, 10 to move closer to base 6 of link mechanism 2. In this case, as viewed in FIG. 3b, one-way transmission mechanism 50 pivots counterclockwise in cooperation with first driven wheel 42, while mechanism 48 pivots clockwise. Mechanism 48 now presents a larger radius relative to the direction of first driven wheel 42, while mechanism 50 presents a smaller radius relative to this same wheel 42. As a result, mechanism 48 is over-centered relative to first driven wheel 42, but mechanism 50 is free to rotate without acting on this same wheel 42. This is again reflected by the clockwise rotation of first driven wheel 42 as viewed in FIG. 3b, as indicated by arrow H.

[0052] As previously explained, with each change in rotational direction, the one-way transmission mechanism 48, 50 that is in an over-center relationship with the first driven wheel 42 will rapidly move away from this state by exhibiting a smaller radius that allows the one-way transmission mechanism 48, 50 to pivot without interacting with the first driven wheel 42. Conversely, the other one-way transmission mechanism will rapidly exhibit an larger radius to the first driven wheel 42, placing it in an over-center relationship with the first driven wheel 42.

[0053] By virtue of the above-mentioned features, a clock mechanism for transmitting rotational motion between a driving wheel and a driven wheel, with one-way conversion, is obtained that exhibits a simple, accurate and reliable construction and assembly mode. Moreover, this mechanism operates with less friction than the above-mentioned conventional solutions, thus offering greater efficiency.

[0054] The practice of the present invention is not limited to the precise geometries of the various components of the mechanism shown and described, and indeed, those skilled in the art will have no particular difficulty adapting the present teachings to implement a transmission mechanism that conforms to the features of the present invention by implementing multiple arms of the linkage mechanism suited to particular needs, such as the number and placement of flexible portions of the arms, or even the shape of the one-way transmission mechanism or the method of arranging the one-way transmission mechanism within the transmission mechanism.

[0055] As already mentioned above, such a transmission mechanism is perfectly suitable for incorporation into an automatic winding mechanism for transmitting the bidirectional movement of the winding weight to a mechanical energy storage mechanism, but it could also be implemented in connection with any other type of suitable horological system without departing from the scope of the present invention, it being noted that in this case the winding weight can advantageously be arranged to exhibit an oscillatory movement of low amplitude, preferably less than 20 degrees, more preferably less than 10 degrees, in favour of assembling a compact automatic winding mechanism.

Claims

1. A transmission mechanism (1) for transmitting the movement of a drive wheel of a timepiece movement to a driven wheel, comprising: a drive plate (40) kinematically linked to the drive wheel and configured to pivot about a first fixed axis of rotation in response to the movement of the drive wheel; and a linkage (2) having a flexible portion (36) and supporting a one-way transmission mechanism (18, 20) arranged to cooperate with a drive surface of an output wheel (4) configured to link to the driven wheel to drive the drive surface when the drive wheel is displaced in a first displacement direction, the linkage (2) comprising a base (6) fixed to the drive plate (40) and arranged for rotational movement about the first fixed axis of rotation in response to movement of the drive wheel; and the link mechanism (2) comprises a first arm (8, 10) extending from the base (6) and supporting the one-way transmission mechanism (18, 20) at a distal end of the first arm (8, 10), and the flexible portion (36) is disposed on the first arm (8, 10); A transmission mechanism (1) characterized by:

2. 2. A transmission mechanism (1) according to claim 1, characterized in that said first arm (8, 10) carries at least one additional flexible portion (36).

3. 3. A transmission mechanism (1) according to claim 1 or 2, characterized in that the output wheel (4) is configured to pivot about a second fixed axis of rotation (30), and the distal ends of the first arms (8, 10) are fixed to radial guide arms (26, 28) arranged to pivot about the second fixed axis of rotation (30) while being rotatable relative to the output wheel (4).

4. The one-way transmission mechanism (18, 20) is disposed at the distal end so as to be pivotable relative to the distal end about a third movable axis of rotation (22, 24), and supports a contact surface disposed in an over-center relationship with the drive surface of the output wheel (4), whereby the contact surfaces drive the drive surfaces in a first relative rotation direction between the radial guide arms (26, 28) and the output wheel (4); and the contact surfaces are displaced in a direction opposite to the direction of relative rotation between the radial guide arms (26, 28) and the output wheel (4) without driving the drive surfaces. A transmission mechanism (1) according to claim 3, characterized in that

5. 5. A transmission mechanism (1) according to claim 4, characterized in that the first arm (8, 10) or the radial guide arm (26, 28) supports an elastic return mechanism (32) arranged to act on the one-way transmission mechanism (18, 20) and to direct the one-way transmission mechanism (18, 20) towards a predefined rest position.

6. 6. The transmission mechanism according to claim 1, wherein the link mechanism (2) supports a second arm (8, 10) having similar structural characteristics as the first arm (8, 10) and supporting an additional one-way transmission mechanism (18, 20), the additional one-way transmission mechanism (18, 20) being arranged to drive the drive surface of the output wheel (4) when the drive wheel is displaced in a second displacement direction opposite to the first displacement direction.

7. 7. A transmission mechanism according to claim 6, characterized in that the first arm (8, 10) and the second arm (8, 10) extend in respective general directions inclined relative to each other by an angle of between 70° and 110°.

8. 8. An automatic winding mechanism comprising a transmission mechanism (1) according to any one of claims 1 to 7, characterized in that it comprises a winding weight adapted to be attached to a frame element of the timepiece movement so as to be pivotable relative to said frame element and having a kinematic link with said drive plate (40).

9. 9. An automatic winding mechanism according to claim 8, characterized in that the winding weight is arranged to exhibit an oscillatory motion with an amplitude of less than 20 degrees.

10. A timepiece movement comprising a transmission mechanism (1) according to any one of claims 1 to 7.

11. 10. A timepiece movement with automatic winding mechanism according to claim 8 or 9, wherein the output wheel (4) comprises a drive gear (44) having a kinematic link with an end of an elastic mechanical energy storage mechanism so as to be able to store energy in said elastic mechanical energy storage mechanism.

12. A timepiece comprising a timepiece movement according to claim 10 or 11.

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