CH715317B1 - Timepiece comprising an adjustable friction device. - Google Patents

Abstract

The present invention relates to a timepiece (1) comprising a frame (2) and at least one mobile mounted in rotation about an axis on said frame, and further comprising a friction device (4) comprising an elastic blade (41) provided at a first end with an anchoring member on said frame and at a second end with a friction member (43) on at least a portion of said mobile so as to apply a frictional force thereto. According to the invention, the friction device (4) comprises a member (44) for mobilizing the elastic blade (41) arranged in kinematic connection on the frame (2) with a drive member (45) such that said mobilization member is movable on the frame (2) between at least one rest position in which said mobilization member (44) applies no force on said elastic blade (41) and an active position in which said mobilization member (44) applies to said blade (41) an adjustable stress by means of the drive member (45) to adjust said friction force applied because the friction member on the mobile.

Description

Technical area

The present invention relates to the field of watchmaking. It relates, more particularly, to a timepiece comprising an adjustable friction device adapted to provide adjustable friction on a timepiece wheel set.

State of the art

[0002] In the field of watchmaking, many friction mechanisms and devices are known which are suitable for applying to the axis or rim of a rotating mobile of a watch movement, often a second or chronograph wheel in particular, a force friction intended in particular to reduce the jerks of rotation of the mobile and the quavering of a needle arranged in kinematic connection with the latter. Such friction devices are among others described in the documents CH 216726 A, CH 226488 A, CH 242662 A or even CH 506824 A.

[0003] The quavering problem occurs in particular with certain chronograph movements or indirect seconds mechanisms, in which the seconds hand is carried by a moving part which is not part of the gear train of the movement in conjunction with the driving source thereof. this. This quavering, which corresponds to irregular jumps of the hand visible to the naked eye, is due to the movement of the gears of the mobile coupling(s) of the hand to the gear train of the movement.

[0004] A difficulty encountered with known friction devices resides in the adjustment of the friction force applied to the watch wheel to be braked, not only during the initial assembly of the watch movement, but also during the life of the watch movement. this. Indeed, with the rate of the movement and the possible wear of the parts and their lubrication, the friction force is caused to vary over time. But the friction force must not be too great, otherwise the movement loses too much amplitude. It is therefore necessary to be able to simply adjust and correct the friction force applied to optimize the wobbling of an indirect seconds hand (carried by a chronograph mobile or other) according to the manufacturing tolerances of the components of the latter and/or the desired use of the watch movement.

[0005] Adjustable friction mechanisms have also been proposed in the prior art, for example in Chinese patent CN104914704. The friction force is applied to the serge or disc of a watch wheel set to be braked by a blade spring moving radially on the plate of the watch movement so as to tension the spring by adjusting the depth of depression of its heel on staggered levels in the plate. Such a device, however, has the disadvantage of requiring not only a particular and delicate structuring of the plate but also complete dismantling of the movement in order to adjust the friction, which is impractical for the watchmaker and costly for the user. In addition, the fineness of adjustment of the friction force is limited by the number of particular positions that the leaf spring can adopt.

The present invention aims to provide a timepiece provided with an adjustable friction device which is simple and precise and does not suffer from the aforementioned drawbacks of known devices of the prior art.

Disclosure of Invention

[0007] More specifically, the invention relates to a timepiece comprising a frame and at least one mobile mounted in rotation about an axis on said frame, and further comprising a friction device comprising an elastic blade s extending along a longitudinal axis and provided at a first end with an anchoring member on said frame and at a second end with a friction member on at least a portion of said mobile so as to apply a frictional force thereto. According to the invention, the friction device further comprises a member for mobilizing the elastic blade arranged in kinematic connection on the frame with a drive member such that said mobilizing member is movable on the frame between at least a rest position, in which said mobilization member does not apply any force on said elastic blade, and an active position, in which said mobilization member applies on said blade (41) an adjustable stress by means of the drive (45) to adjust said friction force applied, directly or indirectly, by the friction member on the mobile.

The timepiece of the invention has the advantage of providing an extremely simple adjustable friction device in its structure and in its implementation, requiring only the addition of two adjustment elements in the form of the mobilization member and its drive member, which make it possible to apply a variable stress to the elastic blade, and therefore to simply vary the frictional force applied by the friction member. These two adjustment elements are simple to house on the frame of the timepiece, in particular on a plate or a watch movement bridge, without having to substantially modify the overall construction of the movement and its functions. They can also be arranged advantageously so as to be able to access them, at least as far as the drive member is concerned, directly without having to dismantle the entire movement, in particular through adjustment orifices.

[0009] The invention thus advantageously provides an adjustable friction device making it possible to compensate for dimensional variations of the components of a timepiece movement inherent in the industrial manufacturing tolerances of the latter, causing gear backlash responsible for quavering. The end user is thus also offered flexibility in terms of covering and use of a watch movement, which can in particular compensate for variations in the inertia of second hands according to their design and the expected chronometric performance.

In one embodiment, the mobilization member comprises a tongue arranged at least partially under said elastic strip and in permanent contact therewith between its said first and second ends.

In a particular embodiment, the elastic blade comprises along its said longitudinal axis at least a first and a second non-coplanar sections each secured to a said first and second end and interconnected by an intermediate section such as the elastic blade has in a median plane passing through said longitudinal axis a substantially "Z" shape.

According to this embodiment, the tongue of the mobilization member extends under the first section of the elastic strip as far as said intermediate section and in contact with the latter.

[0013] Advantageously, the mobilization member comprises a connecting arm to said tongue, said connecting arm having an L-shaped connecting elbow.

[0014] According to one embodiment of the invention, said drive member comprises a cam arranged rotatably on the frame through an opening formed in the mobilization member such that a rotation of said cam causes a translational movement of said mobilization member on the frame in a direction parallel to said longitudinal axis of the elastic blade.

[0015] In a particular embodiment, the drive member consists in particular of an eccentric. Such a drive member is particularly common and easy to implement, and can easily be actuated by a screwdriver or the like without having to dismantle a movement. It is thus possible when adjusting the friction to reduce the jitter of a chronograph or seconds hand in the center to directly visualize the effect of the adjustment on the movement of the hand without stopping the movement.

Preferably, the drive member is rotatable in an opening formed in the connecting arm of the mobilization member.

In one embodiment, a rotation of the drive member causes a translational movement of said mobilization member and a sliding of said tongue against the intermediate section of the elastic blade capable of causing a movement in a vertical direction of the friction member.

[0018] Finally, according to various embodiments, the friction member at the second end of the elastic blade comprises, where appropriate, a fork and/or an additional friction spring arranged to cooperate with the elastic blade at its said second end, in particular for example in cooperation with a said fork at this said second end.

Brief description of the drawings

[0019] Other details of the invention will appear more clearly on reading the following description, given with reference to the appended drawings in which: FIG. 1 represents an overall view of a timepiece equipped with an adjustable friction device according to the invention in a rest position of said adjustable friction device; FIG. 2 represents an overall view of a timepiece equipped with an adjustable friction device according to the invention in an active position of said adjustable friction device; FIGS. 3A and 3B are respectively side and perspective views of the adjustable friction device of the timepiece of the invention in the rest position of FIG. 1, stripped of the movement plate supporting them; FIGS. 3C and 3D are respectively side and perspective views of the adjustable friction device of the timepiece of the invention in the active position of FIG. 2, stripped of the movement plate supporting them.

Embodiment of the invention

There is shown in Figures 1 to 3D a preferred embodiment of a timepiece and its adjustable friction device according to the invention. In these figures, only the parts essential to understanding the invention and its operation are represented for the sake of clarity and conciseness.

In the example presented, the timepiece 1 is a watch movement equipped with a chronograph function and an adjustable friction device 4 arranged to adjust the friction force applied to a chronograph wheel 3 (shown schematically in Figures 3A and 3C) in order to reduce the quavering of the chronograph hand carried by this mobile. However, such an example of implementation is in no way limiting of the scope of the invention, which can be applied to the braking by friction of any type of horological mobile.

Referring first to Figures 1 and 2, the timepiece 1 comprises a frame 2 formed of a machined plate to receive, in a well-known manner, various components and horological mobiles constituting a movement. Substantially in the center of the plate is formed a counterbore intended to receive a mobile 3 (shown in FIGS. 3A, 3C) such as a chronograph wheel, mounted in rotation about a specific axis 31 (also shown in FIGS. 3A , 3C) on a bearing 5 itself housed on a friction spring 432, in a conventional manner in itself.

[0023] As is well known to those skilled in the art in the field of watchmaking, such a friction spring 432 is not entirely satisfactory for providing adequate braking of the chronograph mobile 3 avoiding the quavering of the chronograph hand it carries without consuming too much driving energy from the movement. The invention also proposes an adjustable friction device 4 making it possible, in the example shown, to complete the conventional friction spring 432 acting on the mobile 3, by providing a friction spring formed of an elastic blade 41 arranged to exert a adjustable friction force on the friction spring 432, to vary the friction force of the latter on the mobile 3. In an embodiment not shown in the figures, the friction device 4 can also replace the friction spring 432 being configured to act directly by friction on said mobile 3 or its axis 31.

The friction device 4 comprises an elastic blade 41 extending along a longitudinal axis L between a first end formed of an anchoring member 42, for example a hook or ring by which said elastic blade 41 is fixed on the frame 2 by means of a screw 6 or the like, and a second end provided with a friction member 43, in this case formed of a fork 431, adapted in the example shown to slip under the spring of friction 432 around the axis 31 of the mobile 3 to be braked. The friction member 43 may also take any other form suitable for exerting a variable friction force on the friction spring 432 or, as previously mentioned, for exerting a direct friction force on the mobile 3 or its axis in the event of absence of friction spring 432.

[0025] The elastic strip 41 has advantageously, but not essentially in the context of the invention, a non-planar shape along its longitudinal axis L. In particular, the elastic strip 41 is composed along its said longitudinal axis L of at least a first planar section 411 starting from the anchoring member 42 and extending for example over a length of the order of 50% to 60% approximately of the total length of the elastic blade 41. This first section 411 and integral with a second section 413 which is not coplanar with the first but substantially parallel to the latter and terminating with the friction member 43 by an intermediate section 412 inclined with respect to the first and second sections 411, 413. The elastic blade 41 thus comprises a longitudinal stall of the second section 413 relative to the first section 411, giving a "Z" shape to the elastic blade 41 seen from the side and in its median longitudinal plane M, as is apparent from FIG. 3A. This unhooking allows on the one hand the positioning of the friction member 43 around the axis 31 of the mobile 3 to be braked, under the existing friction 432, and on the other hand, as will be described later, to provide at the level of the intermediate section 412 a lifting ramp whose length and inclination determine the bending deformation of the elastic blade around its anchor point 42, and therefore the displacement of the friction member relative to the axis 31 of the mobile to make the friction force applied thereto.

The friction device 4 also comprises for this purpose according to the invention a mobilization member 44 of the elastic blade 41 arranged on the frame 2 in kinematic connection with a drive member 45.

As is apparent more particularly from Figures 3B and 3D, the mobilization member 44 consists of an actuating arm housed in a recess machined for this purpose on the plate 2 along the elastic blade 41. The arm of actuation is arranged to move and is guided in translation in its withdrawal along a direction parallel to the longitudinal axis L of the elastic blade 41. The actuating arm forming the mobilization member 44 comprises a tab 441 arranged under the first section of said elastic blade 41 and in permanent contact with the latter as well as with said intermediate section 412 by a distal end of the tongue 441 with respect to the anchoring member 42. A connecting arm 442 having an elbow 443 connecting in L to the tongue 441 forms the body of the mobilization member 44, in which is formed a substantially rectangular or oblong opening 444 in which is slid a drive member 45 of the mobilization member 44, formed of an eccentric in the example shown, rotatable on its own axis in said opening 444. Thus, the mobilization member is movable on the frame 2 between at least one rest position P1, shown in Figures 1, 3A and 3B , in which said mobilization member 44 does not apply by its tongue 441 any thrust force on the intermediate section 412 of said elastic blade 41 and an active position P2, represented in FIGS. 2, 3C and 3D, in which the tongue 441 applies against the intermediate section 412 a thrust force inducing a sliding of said intermediate section 412 on the distal end of the tongue 441 and the lifting in flexion of the blade 41 capable of varying said friction force applied by the friction member 43 to mobile 3 and/or the existing friction by increasing its contact force with mobile 3.

[0028] It is clearly understood with regard to FIGS. 3A to 3D that the adjustable friction device proposed by the timepiece of the invention has great simplicity of construction and operation, as well as an advantage of use for the fitter and/or adjuster watchmaker because the adjustment eccentric 45 can be arranged on the plate 2 to be accessible even after the assembly of a dial and the hands on the watch movement comprising it. friction to the mobile 3 such as an indirect seconds mobile (of a chronograph or of a central seconds for example) while monitoring the jitter and/or the amplitude of movement of the associated hand Another advantage of the invention lies in the simplicity of configuration of the adjustment margin of the friction force applied by the elastic blade 41. Indeed, it suffices to play on the length and the inclination of the intermediate section to provide a range of adjustment more or less I importance of the friction force for the same center distance between the anchor point of the elastic blade 41 and the axis of the mobile 3 to be braked and the same configuration of mobilization member 44 and eccentric 45.

[0029] A timepiece is thus obtained equipped with an adjustment friction that is simple to implement and adjust, which can, if necessary, also be easily mounted on resumption of existing movements or modules in order to provide mobile friction adjustable.

Of course, the particular embodiment described and shown in Figures 1 to 4 is not limiting the scope of the present invention as defined in the claims. A person skilled in the art can in particular easily replace the eccentric 45 with a cam of suitable shape depending on the displacement to be imparted to the mobilization member. He may also use a tab 441 provided with a boss or indentation housed in a groove of complementary shape in a flat elastic blade 41 to move said blade in flexion and vary the friction force applied by the friction member 43 to the mobile to brake. The constituent materials of the elastic blade 41, as well as of the mobilization member 44 and of the drive member 45 can finally be chosen according to the needs of those skilled in the art and the expected mechanical performance without affecting the particular structure. and the operation of the friction device proposed by the invention.

Claims (10)

1. Timepiece (1) comprising a frame (2) and at least one mobile (3) rotatably mounted about an axis (31) on said frame, and further comprising a friction device (4) comprising an elastic blade (41) extending along a longitudinal axis (L) and provided at a first end with an anchoring member (42) on said frame and at a second end with a friction member (43) on at least a portion of said mobile (3) so as to apply a frictional force to it, characterized in that the friction device (4) further comprises a member (44) for mobilizing the elastic blade (41) arranged in connection kinematics on the frame (2) with a drive member (45) such that said mobilization member is movable on the frame (2) between at least one rest position (P1) in which said mobilization member (44 ) does not apply any force to said elastic blade (41) and an active position (P2) in which said mobilization member (44) applies su r said blade (41) an adjustable constraint by means of the drive member (45) to adjust said friction force applied, directly or indirectly, by the friction member (43) on the mobile. 2. Timepiece according to claim 1, characterized in that the mobilizing member (44) comprises a tongue (441) arranged at least partially under said elastic blade (41) and in permanent contact therewith between its say first and second ends. 3. Timepiece according to claim 1 or 2, characterized in that the elastic blade (41) comprises along its said longitudinal axis (L) at least a first and a second non-coplanar sections (411, 413) each integral with a said first (41a) and second end (41b) and interconnected by an intermediate section (412) such that the elastic blade (41) has in a median plane (M) passing through the said longitudinal axis (L) a shape substantially in "Z". 4. Timepiece according to claims 2 and 3, characterized in that the tongue (441) extends under the first section (411) of the elastic strip (41) as far as said intermediate section (412) and at the contact with the latter. 5. Timepiece according to claim 2, characterized in that the mobilization member (44) comprises a connecting arm (442) to said tongue (441), said connecting arm (442) having an elbow (443 ) L-shaped connection. 6. Timepiece according to one of claims 1 to 5, characterized in that said drive member (45) comprises a cam arranged rotatably on the frame through an opening (444) formed in the mobilizing member (44) such that a rotation of said cam causes a translational movement of said mobilizing member on the frame in a direction parallel to said longitudinal axis of the elastic blade (41). 7. Timepiece according to claims 5 and 6, characterized in that the drive member (45) is rotatable in the opening (444) formed in the connecting arm (442) of the member mobilization (44). 8. Timepiece according to claim 6 or 7, characterized in that the drive member is an eccentric. 9. Timepiece according to claim 4 or 5 and one of claims 6 to 8, characterized in that a rotation of the drive member (45) causes a translational movement of said mobilization member (44 ) and a sliding of said tongue (441) against the intermediate section (412) of the elastic strip (41) capable of causing movement in a vertical direction of the friction member (43). 10. Timepiece according to one of claims 1 to 9, characterized in that the friction member (43) comprises a fork (431) and/or an additional friction spring (432) arranged to cooperate with the elastic blade (41) at its said second end.