Self-winding watch movement

Abstract

The watch movement with automatic windup comprises an oscillating weight (7) and a barrel (3) which are arranged concentrically. The oscillating weight is arranged so as to wind up the barrel, which is positioned at the centre of the movement. The barrel drum (13) is mounted on the frame of the movement so as to be rotatable in a single direction of rotation, the single direction causing the barrel (3) to be wound up. The oscillating weight and the barrel drum are also arranged so as to be rigidly connected to one another when the oscillating weight (7) rotates in the single direction of rotation.

Description

[0001] The present invention relates to a self-winding watch movement comprising: a barrel comprising a bung and a barrel drum concentric with the bung, and inside which is wound a mainspring, the latter being attached by its outer coil to the barrel drum and by its inner coil to the bung; a pivoting device and an oscillating mass mounted on the pivoting device and intended to be kinematically connected to the barrel so as to allow the barrel to be wound by the movements of the oscillating mass, the oscillating mass and the pivoting device being arranged so as to be contained in an annular space surrounding the movement. EARLIER ART

[0002] In so-called self-winding watch movements, the movements of the wearer's wrist rotate an inertial mass (called an oscillating mass) which winds the mainspring via a gear train acting in only one direction of rotation.

[0003] One drawback of self-winding watches is that they tend not to be as thin as they could be with a purely manual winding mechanism. This is because the presence of an oscillating weight significantly thickens watch movements equipped with an automatic winding mechanism.

[0004] To remedy this drawback, the use of a peripheral oscillating weight was proposed. Following this earlier solution, the oscillating weight is arranged in an annular space surrounding the movement itself. One advantage of this solution is that the oscillating weight can be housed entirely within the height of the movement, thus not increasing its thickness. A difficulty associated with this solution is that the winding and setting stem must be located outside the path of the oscillating weight. To overcome this difficulty, one proposal was to axially offset the stem relative to the movement. Unfortunately, such an offset inevitably results in a comparable increase in the movement's height.

[0005] Patent document CH 458 213 describes a self-winding watch movement that conforms to the definition given in the preamble and is intended to remedy the aforementioned drawbacks. This known watch movement comprises, on the one hand, an oscillating weight housed in a peripheral area of ​​the movement, entirely within its height, and on the other hand, a winding and setting stem arranged perpendicular to the plane of the movement so as to emerge off-center from its caseback. According to the aforementioned prior document, the oscillating weight is fixed to a rotating ring arranged concentrically with the movement, and this ring has internal teeth arranged to drive the ratchet wheel of the mainspring barrel through a reduction gear consisting of six meshing wheels. The reduction gear of the self-winding mechanism necessarily occupies space.Furthermore, unlike the oscillating weight, this gear train is not confined to a peripheral area of ​​the movement. Under these conditions, it would be advantageous to have a self-winding watch movement whose design would allow it to be even thinner.

[0006] Document WO2010 / 017874 describes a self-winding watch movement comprising a frame carrying a mechanical energy source, a rotating oscillating weight in reference to said frame and a reduction gear arranged to recharge said energy source. BRIEF SUMMARY OF THE INVENTION

[0007] One object of the present invention is to overcome the drawbacks of the prior art just described. The present invention achieves this object, as well as others, by providing a self-winding watch movement that conforms to the attached claim 1.

[0008] According to the invention, the barrel and the oscillating weight are arranged concentrically, with the barrel at the center of the movement, and the annular space in which the oscillating weight is intended to move arranged around the barrel. One advantage of this arrangement is that it allows the barrel to have the largest possible diameter relative to the outer diameter of the movement.

[0009] According to the invention, the mainspring barrel is mounted on the movement frame so as to rotate only in one direction. Furthermore, the oscillating weight and the mainspring barrel are arranged so as to be fixed to each other when the oscillating weight rotates in said single direction. Finally, said single direction of rotation corresponds to the winding direction of the mainspring barrel.

[0010] It will first be understood that the above characteristics allow the oscillating weight to drive the mainspring barrel with a drive ratio of 1. In other words, when the oscillating weight completes one full revolution in the single direction of rotation, the mainspring barrel also rotates one full revolution in the same direction. Thanks to this characteristic, the automatic winding mechanism according to the invention makes it possible to store mechanical energy in the mainspring barrel more quickly, provided that the torque generated by the oscillating weight is sufficient. According to a first embodiment of the invention, the pivoting device is arranged so that the oscillating weight is free to rotate around the mainspring barrel in both directions, the mainspring barrel being arranged to disengage from the oscillating weight when the latter rotates in the opposite direction to the single direction of rotation.In other words, the oscillating weight and the barrel drum are linked to each other by a unidirectional coupling, so that the barrel drum can remain stationary when the oscillating weight rotates in the opposite direction to the said unidirectional rotation. It will be understood that, according to this first variant, the pivoting device must be double, so that both the oscillating weight and the barrel drum can rotate relative to the plate, and can also rotate relative to each other.

[0011] According to a second embodiment of the invention, the oscillating weight and the barrel drum are arranged so that they are permanently fixed to each other, such that the pivoting device prevents both the oscillating weight and the barrel drum from rotating in the opposite direction to the single direction of rotation. It can be understood that, according to this second embodiment, as with the first, the oscillating weight drives the barrel drum exclusively in the single direction of rotation. Furthermore, the oscillating weight and the barrel drum never have to rotate independently of each other, so a simple pivoting device is sufficient. BRIEF DESCRIPTION OF THE FIGURES

[0012] Other features and advantages of the present invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: therefigure 1 is a perspective view of the back side of a self-winding watch movement which corresponds to a first particular embodiment of the invention, this first embodiment conforming to the first variant of the invention; the figure 2 is a perspective view of the back side of a self-winding watch movement which corresponds to a second particular embodiment of the invention, this second embodiment conforming to the second variant of the invention; the figure 3 is a partial cross-sectional view showing the connection between the oscillating weight and the barrel drum of the self-winding watch movement of the figure 2 . DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0013] There figure 1 Attached is a perspective view of the back side of a self-winding watch movement, which corresponds to a first exemplary embodiment of the invention. figure 1 It shows in particular a low-profile barrel 3 positioned at the center of the movement and a ball bearing 5 surrounding the barrel. Conventionally, the barrel 3 contains a mainspring 11 wound upon itself and fixed to the ball bearing by its outer coil and to a central stopper 9 by its inner coil. figure 1 It also shows an oscillating mass 7 in the shape of a sector of a ring, which is arranged to rotate around the barrel 3, concentrically to the latter. It will be understood that the ball bearing 5 notably fulfills the function of a pivoting device for the oscillating mass.

[0014] It can be seen that the ball bearing 5 has three coplanar and concentric rings. The inner ring is designated 13, the intermediate ring 14, and the outer ring 15. The intermediate ring 14 is fixed to the mainplate (not shown) of the watch movement, while the inner ring 13 and outer ring 15 of the ball bearing 5 are free to rotate independently of each other, concentrically with the intermediate ring 14. It can be understood that, in this example, the ball bearing 5 acts as an interface between the mainspring barrel 3 on the one hand, and the oscillating weight 7 on the other. Indeed, it can be observed that the inner ring 13 of the ball bearing 5 functions as a drum within the mainspring barrel 3. It can also be observed that the outer ring 15 constitutes the rotating part of the pivoting mechanism for the oscillating weight 7, the latter being fixed to the outer ring of the ball bearing (by bonding, for example).

[0015] Looking further into the figure 1 On the one hand, we can see a first elastic ratchet (reference 19) mounted on the movement at 3 o'clock, and on the other hand, we can see that the inner ring 13, which acts as the barrel drum, is higher than the other two rings 14 and 15 of the ball bearing. The inner ring 13 has a raised section with external saw teeth 17 that extend above the level of the upper faces of the other two rings. Furthermore, we can see that the saw teeth of the teeth 17 are arranged to cooperate with the first elastic ratchet 19, which is carried by the fixed ring 14 of the ball bearing 5. It will therefore be understood that the inner ring, in other words the barrel drum, 13 can only rotate in one direction. As will be seen in more detail later, the teeth 17 of the barrel drum act as the winding ratchet for the barrel 3.Indeed, contrary to the usual arrangement, the barrel drum, which is formed by the inner ring 13, is held by the first pawl 19 during the watch's operation, so that it remains fixed. Under these conditions, it is the barrel's lug 9 that is arranged to drive the movement's gear train. According to the present embodiment, the barrel's lug 9 is made of the same material as the pinion of the center pinion, or minute pinion, of the movement. The center pinion is itself connected to the escapement by a gear train, which may be of the conventional type. This gear train is visible in the figure. figure 1 , but the elements that compose it are not referenced. It will be understood from the above that, because the stop 9 of the barrel 3 of this example is fixed to the center pinion, it rotates at a rate of 1 revolution per hour during the operation of the movement.

[0016] It will also be understood that the single direction of rotation in which the ratchet 19 allows the barrel drum 13 to rotate (clockwise in the figure 1 ) corresponds to the winding direction of barrel 3. The figure 1 It also shows a second elastic pawl (reference 21) which is mounted on the outer ring 15, so that it is arranged to rotate with the oscillating weight 7. The pawl 21 is further arranged to cooperate with the teeth 17 of the winding ratchet. It will be understood that the pawl 21 creates a unidirectional coupling between the oscillating weight 7 and the barrel drum formed by the inner ring 13, so that, on the one hand, the oscillating weight 7 drives the barrel drum with it when it rotates in the said single direction of rotation (clockwise in the figure 1 ), and that, on the other hand, the oscillating mass is free to rotate in the opposite direction to the said single direction of rotation without being accompanied by the barrel drum, which is held by the first elastic pawl 19. It will be understood from the above explanations that the self-winding watch movement illustrated in the figure 1 conforms to the first variant of the invention.

[0017] The self-winding watch movement of the figure 1 It also includes a setting stem (referenced 23) which emerges radially from the movement at 3 o'clock. The setting stem can, for example, be connected to the (unreferenced) minute train of the movement in a manner known to those skilled in the art. As already mentioned in relation to the prior art, it is obviously essential that the setting stem 23 be arranged outside the path of the oscillating weight 7. In order to fulfill this latter condition without increasing the thickness of the movement shown in this example, the movements of the oscillating weight 7 are confined within an angular sector that is bounded on both sides. Thus, the figure 1 This shows two elastic stops (referenced 25a and 25b) positioned on the periphery of the movement, on either side of the stem 23, so as to prevent the oscillating weight 7 from entering a small angular sector centered on the setting stem. It will be understood that the two elastic stops 25a and 25b also prevent collisions between the two elastic pawls 19 and 21.

[0018] THE figures 2 et 3 The attached figures are respectively perspective and cross-sectional views of a self-winding watch movement, which corresponds to a second exemplary embodiment of the invention. The watch movement of figures 2 et 3 shares many characteristics with the one just described in relation to the figure 1 The elements of the watch movement of figures 2 et 3 which are identical or analogous to elements of the first embodiment are designated by the same reference number increased by 50. As will be seen in more detail, the few differences between the first and second embodiments are mainly a consequence of the fact that the second embodiment conforms to the second variant of the invention, while the first embodiment conforms to the first variant.

[0019] THE figures 2 et 3 They show in particular a low-profile barrel 53 positioned at the center of the movement and a unidirectional ball bearing 55 surrounding the barrel. The latter comprises a bung 59 and a barrel drum 63, and it can be seen that, conventionally, it also contains a mainspring 61 wound upon itself and attached to the barrel drum 63 by its outer coil and to the bung 59 by its inner coil. figures 2 et 3 also show an oscillating mass 57 in the shape of a sector of a ring, which is arranged to rotate around the barrel 53, concentrically to the latter, and it will be understood that the unidirectional ball bearing 55 fulfills in particular the function of pivoting device for the oscillating mass.

[0020] Referring more specifically to the cross-section of the figure 3 It can be seen that the unidirectional ball bearing 55 comprises two concentric rings (referenced 64 and 65). As is known, the inner ring 64 of the unidirectional ball bearing is fixed to the movement's plate (not shown), while the outer ring 65 is arranged to rotate, but only in one direction of rotation (clockwise in the figure 3 ). It should be noted that those skilled in the art are familiar with unidirectional ball bearings, also known as "one-way" bearings. A description of such a ball bearing can be found, in particular, in patent document CH 694 025. This document is incorporated into the present text by reference. Always referring to the figure 3 As can be seen, the oscillating weight 57 and the barrel drum 63 are both rigidly fixed to the outer ring 65 (for example, by bonding). It will therefore be understood that, according to the second embodiment of the invention, the oscillating weight 57 and the barrel drum 63 are arranged so as to pivot as a single unit. Furthermore, since they are both fixed to the outer ring 65 of the unidirectional ball bearing 55, they can only rotate in the single direction of rotation. It will also be understood that this single direction of rotation corresponds to the winding direction of the barrel 53.

[0021] It will also be understood that, like the oscillating mass 57 of the clockwork movement represented in the figures 2 et 3 can only rotate in one direction; it is not possible to confine it within a particular angular sector. Unlike the first embodiment, the oscillating mass 57 of this example must be able to complete full rotations. The clockwork mechanism illustrated in the figures 2 et 3 is compatible with this requirement. Indeed, it is notably devoid of pawls that could collide with each other, and it also does not have a setting stem emerging radially from the movement. According to this second embodiment, the winding and setting stem (not shown) could, for example, be oriented along an axis perpendicular to the plane of the movement and accessible from the dial side or the case back of the watch.

[0022] It will also be understood that various modifications and / or improvements, obvious to a person skilled in the art, can be made to the embodiments described herein without departing from the scope of the present invention as defined by the appended claims. In particular, a self-winding watch movement according to the first variant of the invention does not necessarily have two pawls. A person skilled in the art will understand that, according to other embodiments, a unidirectional ball bearing could be used to provide one of the two unidirectional couplings. It should be noted that the use of a unidirectional ball bearing in a self-winding watch movement according to the first variant of the invention would eliminate the need to prevent collisions between the pawls, since the watch movement would then have only one pawl.Conversely, a self-winding watch movement conforming to the second variant of the invention does not necessarily include a unidirectional ball bearing. It will be understood that the unidirectional ball bearing could be replaced by a bidirectional ball bearing associated with a ratchet that cooperates with a pawl.

Claims

1. Watch movement with automatic winding comprising: - a barrel (3; 53) comprising a core (9; 59) and a barrel drum (13; 63) concentric with the core, and inside which a power spring (11; 61) is wound, the latter being hooked onto the barrel drum by its outer turn and onto the core by its inner turn; - a pivot device (5; 55) and an oscillating weight (7; 57) mounted on the pivot device and provided to be kinematically connected to the barrel (3; 53) so as to enable the barrel to be wound by the movements of the oscillating weight, the oscillating weight (7; 57) and the pivot device (5; 55) being arranged so as to be contained within an annular space surrounding the movement; - the barrel (3; 53) and the oscillating weight (7; 57) being arranged concentrically, the barrel being located at the centre of the movement; characterised in that the barrel drum (13; 63) is mounted on the frame of the movement so as to be able to rotate in a single direction of rotation, said single direction causing winding of the barrel (3; 53); in that the oscillating weight (7; 57) and the barrel drum (13; 63) are arranged so as to be fixedly attached to one another when the oscillating weight turns in said single direction of rotation so that the oscillating weight (7; 57) drives the barrel drum (13; 63) with a drive ratio which is equal to 1 when the oscillating weight turns in said single direction of rotation; and in that the annular space in which the oscillating weight (7; 57) moves is arranged about the barrel (3; 53).

2. Watch movement as claimed in claim 1, characterised in that the pivot device (5) is arranged so that the oscillating weight (7) is free to turn about the barrel (3) in said single direction of rotation and in the inverse direction, and in that the oscillating weight (7) and the barrel drum (13) are arranged to be disengaged from one another when the oscillating weight turns in the direction opposite to said single direction of rotation.

3. Watch movement as claimed in claim 1, characterised in that the oscillating weight (57) and the barrel drum (63) are arranged so as to be permanently fixedly attached to one another, the oscillating weight being arranged so as to be able to rotate only in said single direction of rotation.

4. Watch movement as claimed in claim 2, characterised in that the pivot device (5) is formed by a ball bearing comprising three concentric rings, a first of the three rings acting as a barrel drum (13), a second (14) of the three rings being fixed to the frame of the movement, and the third ring (15) bearing the oscillating weight (7), and in that it comprises means for causing two unidirectional couplings between the first ring (13) on the one hand and the second ring (14) and the third ring (15) respectively on the other hand.

5. Watch movement as claimed in claim 3, characterised in that the pivot device (55) is formed by a ball bearing comprising two concentric rings (64, 65), a first of the two rings (64) being fixed to the frame of the movement, and the second ring (65) bearing the oscillating weight (57) and the barrel drum (63), and in that it comprises means for causing a unidirectional coupling between the first and the second ring.

6. Watch movement as claimed in claim 5, characterised in that the means for causing a unidirectional coupling between the first and the second ring comprise saw teeth formed on one of the rings and at least one click fixedly attached to the other ring and arranged to cooperate with the saw teeth.

7. Watch movement as claimed in claim 5, characterised in that the ball bearing (55) is a unidirectional ball bearing.

8. Watch movement as claimed in claim 4, characterised in that the means for causing two unidirectional couplings between the first ring (13) on the one hand and the second ring (14) and the third ring (15) respectively on the other hand comprise saw teeth (17) formed on the first ring (13) and two clicks (19, 21) fixedly attached to the second (14) and the third (15) ring respectively, the two clicks being arranged to cooperate with the saw teeth (17).

9. Watch movement as claimed in any one of the preceding claims, characterised in that it comprises a finishing going train actuated by the core (9; 59) of the barrel (3; 53), and in that the finishing going train is arranged so that the core turns at a rate of one turn per hour when the movement is running.

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