Friction system for timepiece movement

Abstract

The invention relates to a friction system for a timepiece movement, comprising: a spindle having a longitudinal axis; a first fixing element mounted for integral rotation with the mandrel; the first fixing element is provided with a first bearing surface; a second fixing element mounted for integral rotation with the mandrel; a toothed member located between the first fixing element and the second fixing element and mounted to rotate freely on the mandrel; characterized in that the toothed member is integral with a socket coupling having a second bearing surface, and the second fixing element comprises a body configured to rotate integrally with the mandrel, and an elastic arm protruding relative to the body and extending towards the toothed member, the elastic arm elastically pressing against the second bearing surface of the socket coupling, the elastic arm is designed to elastically deform under the stress exerted by the second bearing surface and to form a kinematic coupling between the first securing element and the toothed member and between the second securing element and the socket coupling until a predetermined friction torque is reached.

Description

Technical Field

[0001] This invention relates to the field of mechanical clocks and watches.

[0002] More specifically, the present invention relates to a friction system for a watch movement (e.g., for setting time). Background Technology

[0003] Friction systems are commonly used in watch movements. A friction system allows the first and second components to rotate together until a torque limit is reached. Once this limit is exceeded, the two components will no longer rotate together. Such systems are typically used for hour and minute displays, especially in the minute wheel tube that drives the display hands or dial.

[0004] The minute wheel tube is typically knurled / reduced to ensure sufficient friction between it and the pivot. Knurling involves clamping and reducing the diameter of the tube within the minute wheel tube at a position opposite the shoulder or relief groove of the pivot. This clamping operation is a manual task, and its effectiveness depends heavily on the watchmaker's dexterity and skill, making it difficult to predict.

[0005] Properly adjusting the frictional torque is therefore extremely challenging. Therefore, precise control of the applied clamping force is crucial, and traditional manual knurling cannot achieve this level of precision or the required reproducibility.

[0006] Another drawback is that the friction generated by knurling cannot withstand the transmission of high torques and is not resistant to assembly and disassembly.

[0007] Other methods for obtaining friction include using metal foil as described in document FR2394839, but it is difficult to guarantee manufacturing repeatability between different batches.

[0008] Document CH 712197 describes another method for generating friction, including the use of a helical friction spring comprising an inner portion pressing against a first annular support surface integrally rotated with a first toothed member, and an outer portion pressing against a second annular support surface integral with a second toothed member, the inner and outer portions being connected by at least one helical elastic arm.

[0009] However, these solutions are complex to implement and take up a lot of space, making it impossible to realize certain functions in watch movements. Summary of the Invention

[0010] The purpose of this invention is to overcome at least one of the above-mentioned defects.

[0011] Another objective of this invention is to provide a friction system that can transmit high torque, is easy to manufacture, and is easy to control the repeatability of the applied friction torque.

[0012] The present invention can also provide a friction system with limited space, wherein the radial space occupied by the friction system is determined by the space occupied by the toothed component, rather than by the space occupied by the friction system itself.

[0013] Therefore, the present invention relates to a friction system for a watch movement, the friction system comprising: a spindle having a longitudinal axis L, designed to be mounted in a watch movement; a first fixing element mounted to rotate integrally with the spindle; the first fixing element having a first support surface; a second fixing element mounted to rotate integrally with the spindle; and a toothed member located between the first fixing element and the second fixing element, the toothed member being mounted to rotate freely on the spindle.

[0014] According to the invention, the toothed member is integral with a socket connector (i.e., mounting sleeve) having a second support surface, and the second fixing element includes a body configured to rotate integrally with a spindle, and an elastic arm protruding relative to the body and extending toward the toothed member, the elastic arm being elastically pressed against the second support surface of the socket connector, the elastic arm being designed to elastically deform under stress applied to the second support surface, and forming kinematic connections between the first fixing element and the toothed member and between the second fixing element and the socket connector (which is integral with the toothed member), until a predetermined frictional torque is reached.

[0015] The friction system according to the invention has a structure that allows full utilization of the entire length of the spindle while limiting the overall space occupied by the system in the radial direction. Therefore, this friction system is easier to assemble into watch movements, especially those containing multiple complex functions.

[0016] According to the present invention, the frictional torque can be perfectly adjusted by axially controlling the press-fitting of the second fixing element on the mandrel. The stress applied to the socket connector by the elastic deformation of the elastic arm can achieve a more gradual increase in the frictional torque, which helps to accurately and repeatably set the predetermined frictional torque.

[0017] Furthermore, this friction system according to the invention can withstand continuous and repeated assembly / disassembly.

[0018] In addition to the features mentioned in the preceding paragraphs, the friction system according to the invention may also have one or more of the following supplementary features, which may be employed individually or in any technically feasible combination:

[0019] -The elastic arm extends along an axis that is substantially parallel to the longitudinal axis of the mandrel;

[0020] - The second support surface is a tapered support surface;

[0021] - The second support surface is an internal support surface, which is formed at the boring or reamed hole in the socket connector and is inclined toward the longitudinal axis of the mandrel;

[0022] - The second support surface is a tapered outer support surface, which is formed on the outer periphery of the socket connector and slopes outward from the socket connector;

[0023] -The elastic arm elastically presses against the second support surface of the socket connector at its free end;

[0024] - The free end of the elastic arm has a rounded or chamfered shape;

[0025] - The first support surface of the first fixing element is planar or conical;

[0026] -The socket connector and the toothed component are made as a single unit;

[0027] -The socket connector is a separate component attached to the toothed member;

[0028] - The socket connector is press-fitted onto the tubular portion of the toothed component.

[0029] The present invention also relates to a watch movement comprising a friction system according to the present invention.

[0030] The present invention also relates to a method for assembling a friction system according to the present invention, the method comprising the following steps:

[0031] - Provides spindles;

[0032] - Press the first fixing element onto the mandrel at a predetermined axial position;

[0033] - The first toothed component is slid on the spindle to the first fixed element, so that the first toothed component contacts the first fixed element; the first toothed component and the socket connector are integrated;

[0034] - The second fixing element is progressively pressed onto the mandrel with the elastic arm oriented toward the socket connector so as to press the elastic arm against the socket connector, thereby achieving a triboelectric kinematic connection between the first fixing element and the first toothed member and between the second fixing element and the socket connector (which is integral with the toothed member) until a predetermined frictional torque is achieved. Attached Figure Description

[0035] Other features and advantages of the invention will become more apparent from the following detailed description given by way of non-limiting example with reference to the accompanying drawings, in which:

[0036] - Figure 1A perspective view of a first exemplary embodiment of a friction system according to the present invention is shown;

[0037] - Figure 2 It shows Figure 1 An exploded view of the friction system shown.

[0038] - Figure 3 It shows Figure 1 A longitudinal cross-sectional view along axis AA of a first exemplary embodiment of the friction system shown;

[0039] - Figure 4 It specifically shows Figure 1 A detailed view of the contact area where friction is generated in the friction system shown.

[0040] - Figure 5 This is a detailed view showing the contact area that generates friction according to a variant embodiment of the friction system according to the present invention;

[0041] - Figure 6 An exploded view of a second exemplary embodiment of the friction system according to the present invention is shown;

[0042] - Figure 7 It shows Figure 6 A longitudinal cross-sectional view along axis AA of a second exemplary embodiment of the friction system shown;

[0043] - Figure 8 A longitudinal cross-sectional view along axis AA is shown for a third exemplary embodiment of the friction system according to the present invention;

[0044] - Figure 9 This is a schematic diagram of a clock whose movement is equipped with a friction system according to the present invention. Detailed Implementation

[0045] refer to Figure 1 The image shows a first exemplary embodiment of a friction system 100 according to the present invention. The system includes a spindle 1 designed for mounting in a watch movement 200; the spindle 1 extends along a central longitudinal axis L constituting its axis of rotation. The spindle 1 may include multiple segments with different diameters and / or different shapes.

[0046] The spindle 1 carries a first toothed member 3, such as a wheel, which is mounted to rotate freely on the spindle 1. Optionally, the first toothed member 3 may be a gear shaft or other element designed to be mounted on the spindle 1 by friction.

[0047] The spindle 1 can also carry multiple toothed components integrated with the spindle 1, which can have various known shapes according to the needs of those skilled in the art.

[0048] Spindle 1 is, for example, a wheel tube.

[0049] like Figure 1 As shown, the spindle 1 includes a second fixed toothed member 5 integrally formed with the spindle 1. This second fixed toothed member 5 can be a gear shaft as shown, or it can be a wheel. In the example shown, the second toothed member 5 is integrally formed with the spindle 1. According to an alternative embodiment, the second toothed member 5 can be press-fitted onto the spindle 1, thereby moving integrally with the spindle 1.

[0050] like Figure 2 As shown, the figure illustrates an exploded view of the first exemplary embodiment of the friction system 100 according to the present invention. The friction system 100 includes a first fixing element 2 that forms a first support element, such as an annular flange 2, which is press-fitted onto a spindle 1 so as to move integrally with the spindle 1.

[0051] The annular flange 2 has a first annular support surface 20, which serves as a first friction surface between the annular flange 2 and the first toothed member 3. The first toothed member 3 rests on the annular support surface 20 via its bottom surface.

[0052] The friction system 100 also includes a second fixing element 7 press-fitted onto the spindle 1. A first toothed member 3 is mounted between the first fixing element 2 and the second fixing element 7. The axial position of the second fixing element 7 along the longitudinal axis L allows for a triboelectric kinematic connection and enables adjustment of the friction force of the friction system 100.

[0053] The friction system 100 also includes a socket connector 4 integral with the toothed member 3, the socket connector 4 having a second support surface 42 that mates with the second fixing element 7. The second support surface 42 is designed to receive and mate with the second fixing element 7, which is press-fitted onto the spindle 1. Therefore, the second support surface 42 forms the second friction surface of the friction system 100 located between the first toothed member 3 and the second fixing element 7.

[0054] according to Figures 1 to 3 In the exemplary embodiment shown, the socket connector 4 and the first toothed member 3 are integrally formed. In this exemplary embodiment, the socket connector 4 protrudes relative to the plate-like portion of the first toothed member 3, and its protrusion direction is opposite to that of the lower surface supported on the annular support surface 20 of the annular flange 2.

[0055] For example, the socket connector 4 has a tapered boring / reamed hole with a tapered inner surface inclined toward the longitudinal axis L of the spindle 1. The tapered inner surface of the socket connector 4 forms the second support surface 42 of the friction system 100 according to the invention.

[0056] Other profiles of the hole (not necessarily linear) are also feasible, as long as the inner surface of the hole has a profile inclined toward the longitudinal axis L of the mandrel 1, without deviating from the scope of the invention. However, a tapered profile with a linear inclination is preferred.

[0057] The second fixing element 7 of the friction system 100 includes a body 72 having a central hole 73 and an elastic arm 71 extending relative to the body 72 in the outer peripheral region of the body 72. The elastic arm 71 extends in a direction substantially parallel to the longitudinal axis L. The body 72 is mounted on the spindle 1 via the central hole 73, preferably by press-fitting.

[0058] The flexible arm 71 has a free end 74 configured to elastically press against the second support surface 42 of the socket connector 4.

[0059] The free end 74 of the elastic arm 71 can have various shapes, for example, such as Figure 4 The rounded shape shown, or as Figure 5 The chamfered shape shown. The chamfered shape advantageously increases the contact surface between the elastic arm 71 and the second support surface 42 (preferably tapered) of the socket connector 4, thereby increasing the frictional torque of the friction system 100.

[0060] like Figure 3 As shown, after the friction system 100 is assembled, the free end 74 of the elastic arm 71 is constrained by the geometry of the second support surface 42 and undergoes elastic deformation to a certain extent toward the interior of the system (i.e. toward the axis L), depending on the axial position of the fixing element 7 relative to the first toothed member 3. The elastic deformation of the elastic arm 71 due to bending (the degree of deformation may be large or small) is proportional to the stress on the first toothed member 3.

[0061] Therefore, the generation of frictional torque in the friction system 100 according to the invention (to a greater or lesser degree) depends on the position of the second fixing element 7 being press-fitted onto the spindle 1, and thus depends on the stress applied by the elastic arm 71 on the socket connector 4.

[0062] According to the present invention, the frictional torque can be perfectly adjusted by precisely pressing the second fixing element 7 onto the mandrel 1. The stress applied to the socket connector 4 by the elastic deformation of the elastic arm 71 allows for a very precise frictional torque, wherein the frictional torque changes gradually and controllably as the second fixing element 7 is pressed in. This makes it easier to precisely set the desired frictional torque based on the position of the second fixing element 7 relative to the first toothed member 3. Furthermore, the setting of the frictional torque is repeatable because it is largely independent of the manufacturing tolerances of the individual components of the friction system 100.

[0063] Therefore, the stress applied by the elastic arm 71 can be adjusted by the relative interval between the second fixing element 7 and the first toothed member 3. More specifically, the stress applied by the elastic arm 71 can be adjusted by the relative interval along the longitudinal axis L between the second fixing element 7 and the second support surface 42 (preferably tapered) of the socket connector 4, thereby adjusting the frictional torque that the system can withstand before the first toothed member 3 pivots relative to the spindle 1. This design makes the setting of the (frictional torque) extremely simple and easy to reproduce.

[0064] Therefore, once all parts are assembled, the elastic arm 71 of the second fixing element 7 forms a kinematic connection between the first fixing element 2 and the first toothed member 3 and between the second fixing element 7 and the first toothed member 3 via the plug connector 4, until a predetermined frictional torque is reached at the toothed member 3.

[0065] Preferably, the second fixing element 7 has at least three elastic arms 71 to provide better force distribution.

[0066] Preferably, such as Figures 1 to 3 As shown, the second fixing element 7 has four elastic arms 71.

[0067] Preferably, these elastic arms 71 are evenly distributed around the periphery of the body 72 and have the same angular distance from each other, so as to provide good pressure distribution on the tapered support surface 42 of the socket connector 4.

[0068] exist Figures 1 to 3 In the exemplary embodiment shown, the four elastic arms 71 are arranged at 90° intervals. If there are more elastic arms, such as six, they are arranged at 60° intervals.

[0069] according to Figures 6 to 7 In the second exemplary embodiment of the present invention shown, the plug connector 4 is an additional component that is directly press-fitted onto the first toothed member 3 in order to secure the plug connector 4 to the toothed member 3.

[0070] For example, the first toothed member 3 includes a convex portion supported by the plate-like portion of the toothed member 3, such as a boss, tenon, sleeve, tongue, etc., which is designed to mate with a concave portion provided on the socket connector 4, such as a countersunk hole, mortise, or boring / reaming hole.

[0071] Of course, the positions of the convex and concave portions can be interchanged, such that the first toothed member 3 includes a concave portion formed on its plate-like portion, and the socket connector 4 carries the convex portion.

[0072] exist Figure 6 and Figure 7In the exemplary embodiment shown, the first toothed member 3 includes a tubular receiving portion 31, and the plug connector 4 has a boring / reamed hole 44 configured to engage with the tubular receiving portion 31 by press fitting.

[0073] In particular, this second exemplary embodiment allows for a more flexible setting of the diameter of the socket connector 4, and thus a more flexible setting of the extension range of the second support surface 42, without being limited by the size of the plate-shaped portion and teeth of the first toothed member 3 associated with the operation of the watch movement 200.

[0074] This second exemplary embodiment enables an increase in the frictional torque of the friction system 100, specifically by increasing the diameter of the connector 4 and the second fixing element 7, thereby increasing the number of elastic arms 71 on the outer periphery of the body 72 that contact the second support surface 42 to form friction. Therefore, this exemplary embodiment is preferred when a high frictional torque is required.

[0075] Figure 8 A variant embodiment of the friction system 100 according to the present invention is shown. This variant embodiment shows the plug connector 4 being press-fitted onto the first toothed member 3; however, this variant embodiment is also applicable to cases where the plug connector 4 and the first toothed member 3 are integrally formed, as referenced above. Figures 1 to 3 As stated above.

[0076] In this variant embodiment, the plug connector 4 has an outer support surface formed around its periphery, which constitutes the second support surface 42 of the friction system 100 according to the invention. This outer support surface slopes outward from the plug connector 4.

[0077] Preferably, the external support surface is a tapered surface, but other profiles are also possible without departing from the scope of the invention.

[0078] Therefore, in this embodiment, when the second fixing element 7 is pressed onto the mandrel 1 to a greater or lesser degree, the elastic arm 71 undergoes elastic deformation toward the outside of the system 100, that is, it undergoes elastic deformation away from the axis L relative to its neutral rest position.

[0079] This variation facilitates the lubrication of the support surface 42, which is the surface in contact with the elastic arm 71. This variation also provides a multiplication effect of frictional torque when the second fixing element 7 is press-fitted, because the contact point between the elastic arm 71 and the support surface 42 is radially further away from the center of the spindle 1.

[0080] The friction system 100 according to the invention is, for example, a friction system for setting the time of a watch movement 200.

[0081] The present invention also relates to a watch movement 200 including a friction system 100 according to the present invention, and a watch 300 including such a watch movement 200.

[0082] The present invention also relates to a method for assembling a friction system according to the present invention, the method comprising the following steps:

[0083] - Provides spindle 1;

[0084] - Press the first fixing element 2 onto the mandrel 1 at a predetermined axial position;

[0085] - Slide the first toothed member 3 on the spindle 1 to the position of the first fixing element 2 so that the first toothed member 3 contacts the first fixing element 2; the first toothed member 3 is integrated with the socket connector 4;

[0086] - The second fixing element 7 is gradually pressed onto the spindle 1 with the elastic arm 71 oriented toward the socket connector 4, so that the elastic arm 71 is pressed against the socket connector 4, thereby obtaining a triboelectric kinematic connection between the first fixing element 2 and the first toothed member 3 and between the second fixing element 7 and the socket connector 4 which is integral with the toothed member 3, until a predetermined frictional torque is obtained.

[0087] Of course, the present invention is not limited to the examples shown, and can have various variations and modifications that are obvious to those skilled in the art without departing from the scope of the invention as defined by the claims.

Claims

1. A friction system (100) for a watch movement (200), comprising: - A spindle (1) having a longitudinal axis (L), the spindle (1) being designed to be mounted in the watch movement (200); - A first fixing element (2) is mounted to rotate integrally with the mandrel (1); the first fixing element (2) has a first support surface (20); -A second fixing element (7) is installed to rotate integrally with the mandrel (1); - A toothed member (3) located between the first fixing element (2) and the second fixing element (7), the toothed member (3) being mounted to rotate freely on the spindle (1); The toothed member (3) is integral with the socket connector (4) having a second support surface (42); the second fixing element (7) includes a body (72) configured to rotate integrally with the spindle (1), and an elastic arm (71) protruding relative to the body (72) and extending toward the toothed member (3), the elastic arm (71) elastically pressing against the second support surface (42) of the socket connector (4), the elastic arm (71) being designed to elastically deform under stress applied to the second support surface (42), and forming kinematic connections between the first fixing element (2) and the toothed member (3) and between the second fixing element (7) and the socket connector (4) until a predetermined frictional torque is reached.

2. The friction system (100) for a watch movement (200) according to claim 1, characterized in that, The elastic arm (71) extends along an axis that is substantially parallel to the longitudinal axis (L) of the spindle (1).

3. The friction system (100) for a watch movement (200) according to any one of the preceding claims, characterized in that, The second support surface (42) is a tapered support surface.

4. The friction system (100) for a watch movement (200) according to any one of the preceding claims, characterized in that, The second support surface (42) is an internal support surface, which is formed at the boring or reamed hole in the socket connector (4) and is inclined toward the longitudinal axis (L) of the spindle (1).

5. The friction system (100) for a watch movement (200) according to any one of claims 1 to 3, characterized in that, The second support surface (42) is an external support surface, which is formed on the outer periphery of the socket connector (4) and slopes outward from the socket connector (4).

6. The friction system (100) for a watch movement (200) according to any one of the preceding claims, characterized in that, The elastic arm (71) elastically presses against the second support surface (42) of the socket connector (4) at its free end (74).

7. The friction system (100) for a watch movement (200) according to claim 6, characterized in that, The free end (74) of the elastic arm (71) has a rounded or chamfered shape.

8. The friction system (100) for a watch movement (200) according to any one of the preceding claims, characterized in that, The first support surface (20) of the first fixing element (2) is planar or conical.

9. The friction system (100) for a watch movement (200) according to any one of the preceding claims, characterized in that, The connector (4) and the toothed component (3) are integrated into one piece.

10. The friction system (100) for a watch movement (200) according to any one of claims 1 to 8, characterized in that, The socket connector (4) is a separate component attached to the toothed member (3).

11. The friction system (100) for a watch movement (200) according to claim 10, characterized in that, The connector (4) is press-fitted onto the tubular receiving portion (31) of the toothed member (3).

12. A watch movement (200) comprising a friction system (100) according to any one of the preceding claims.

13. A method for assembling a friction system (100) according to any one of claims 1 to 11, the method comprising the steps of: - Provides a mandrel (1); - Press the first fixing element (2) onto the mandrel (1) at a predetermined axial position; - Slide the first toothed member (3) on the spindle (1) to the first fixing element (2) so that the first toothed member (3) contacts the first fixing element (2); the first toothed member (3) and the socket connector (4) are integrated; - The second fixing element (7) is progressively pressed onto the spindle (1) with the elastic arm (71) oriented toward the socket connector (4) so ​​as to press the elastic arm (71) against the socket connector (4), thereby obtaining a triboelectric kinematic connection between the first fixing element (2) and the first toothed member (3) and between the second fixing element (7) and the socket connector (4) until a predetermined frictional torque is obtained.

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