Mechanical timepiece movement

Abstract

A mechanical timepiece movement comprising: a barrel; an escapement wheel set associated with the mechanical resonator; a display wheel set (30) intended to carry a display member, in particular a timepiece pointer (48), and rotatably driven by the barrel; and a brake spring (10) arranged to generate a brake torque on the display wheel set when the display wheel set is subjected to the rotational driving torque in order to prevent chatter of the display member. The mechanical timepiece movement further comprises an intermediate member, in particular a gasket, between the brake spring and the stem (36) of the display wheel set, the intermediate member being mounted so as to rotate freely on the stem. The intermediate member and the brake spring are arranged such that the intermediate member remains stationary and does not rotate in normal operation. The brake spring exerts a pressing force on the intermediate part generally in the direction of the stem in order to generate the brake torque.

Description

Technical Field

[0001] The present utility model relates to a mechanical watch movement, which includes a wheel set carrying a display member, and in particular a pointer, and is equipped with an anti-vibration device, also known as an anti-shock device, formed by a braking device acting on the wheel set, to prevent the display member from vibrating during rotation, and also to prevent the display member from floating when stationary, where appropriate. Background Art

[0002] Document CH 580301 discloses an anti-vibration device for a watch wheel set, in particular a chronograph wheel set (hereinafter also referred to as a "chronograph wheel set"), which includes a arbor equipped with a pinion that meshes with a clutch wheel (hereinafter also referred to as a "driving wheel"), thus forming a coupling device for the chronograph mechanism. It should be noted that the arbor equipped with a pivot to guide its rotation is also referred to as a "shaft" in the watchmaking industry. The anti-vibration device for the second hand for the chronograph function is formed by a friction device that includes a hairspring that abuts the arbor obliquely. For this purpose, the arbor has a frustoconical shoulder, and the hairspring has a support point in the angle formed by this shoulder and a cylindrical part, the diameter of which corresponds to the minimum diameter of the shoulder, and an inclined force is applied to the arbor at this point, such that the teeth of the pinion press against the driving wheel, and such that the lower annular surface of the arbor opposite to and orthogonal to the axis defined by the arbor axially presses against a bearing, in which the chronograph wheel set rotates. This spring is designed to be straight without stress. This spring is fastened to the frame of the movement on one side of the first end, while a part on one side of the second end is in a tensioned state and presses against the arbor, as explained above.

[0003] For various reasons, this anti-vibration device causes problems in controlling the torque of the frictional force applied to the chronograph wheel set. In addition, there is no way to adjust the torque of this frictional force. Subsequently, when the chronograph pointer (timing pointer) is removed, the spring is subjected to an axial force, which may damage this spring.

[0004] The document DE 6800934 U describes a solution for improving the control of the torque of the frictional force applied to the seconds wheel set. According to the teachings of this document, a wire spring or leaf spring is fastened to a plate at its first end portion by riveting technology, the plate being held in suspension by a rivet having a head with a screw-shaped groove, which is arranged on the side of the rod opposite to the side on which the plate is located. The rivet has an intermediate cylindrical portion which is inserted into a hole in the rod by means of a friction fit, thereby allowing the rivet, and thus the plate, and thus the first end portion of the spring to undergo a certain rotation with the help of a tool. The second end portion of the friction spring is free and abuts radially against a plastic washer which is press-fitted / pressed onto the arbor of the seconds wheel set, this washer having a lateral groove in which the second end portion of the spring is placed. This system is difficult to assemble in a watch movement. First, the friction spring must be fastened to the plate by inserting the first end portion of the friction spring into a groove and then pressing material against the two edges of this groove to perform the first riveting operation. After inserting the rivet into the hole in the rod from the other side, the plate with the friction spring must be brought to the inside of the rod. Then, the end of the rivet must be crushed and the second riveting operation must be performed to fasten the plate to the rivet. It can be seen that at each stage of assembling the friction spring to the plate and then to the rod via two consecutive riveting operations, there is a high risk of damaging the friction spring. Finally, the rod, plate and friction spring assembly are assembled in the watch movement, a priori by inserting the pivot of the arbor of the seconds wheel set carrying the grooved washer into a bearing arranged in the relevant rod. This assembly requires that the spring does not stack on top of the grooved washer, since the spring is rigidly connected to the rod and since the grooved washer designed to receive the free end of the spring in a tensioned state is rigidly connected to the arbor. Thus, there is a first assembly / dismantling position for the spring and a second working position in which the free end of the spring is brought into the groove in the washer and the spring is tensioned. To move from one position to the other, the watchmaker must use a tool acting on the rivet head, which causes the spring to lose the set tension when removed for maintenance. Therefore, each time the seconds wheel set is assembled, the torque of the braking force must be readjusted. The assembly method described here is difficult and time-consuming to implement.

[0005] Furthermore, this anti-chattering device does not provide a perfect solution to the problem of regulating the force applied to the seconds wheel set to prevent it from chattering, because the frictional force is defined especially by the profile of the lateral grooves of the plastic washer and the shape of the ends of the spring inserted into these grooves and radially pressed against the washer. This frictional force is difficult to control and reproduce because it highly depends on the dimensions of the spring and the grooves, their corresponding configurations, and their corresponding surface finishes. Another problem results from the fact that assembling the intermediate member on the arbor of the seconds wheel set will increase the radial play of this wheel set and thus cause greater variations than when there is no such intermediate member (especially when the spring is directly supported on a conventional arbor with less radial play). In addition, if the watch is subjected to vibrations or shocks, the second free end of the spring may become disengaged from the grooved washer and will no longer ensure a constant braking torque. Worse still, if a severe impact occurs, the spring fastening plate held in place only by friction may move angularly and change the braking setting. Summary of the Utility Model

[0006] The object of the present utility model is to solve the above problems of the prior art and also to propose an anti-chattering device for a display wheel set arranged outside the transmission mechanism (gear train) from the barrel to the escapement wheel set, which device is easy to install and, in a preferred alternative embodiment, can be installed in a preliminary step before installing the wheel set in question.

[0007] To this end, the present utility model relates to a mechanical watch movement, which comprises: a barrel; an escapement wheel set associated with a mechanical resonator; a display wheel set including an arbor and intended to carry a display member; and a braking device associated with the display wheel set and including a braking spring and an intermediate member arranged between the braking spring and the arbor of the display wheel set. This display wheel set can be rotatably driven by the barrel but does not form part of the transmission mechanism from the barrel to the escapement wheel set. The braking spring is arranged such that once the display wheel set is subjected to a rotational driving torque, it can generate a braking torque on the display wheel set via the intermediate member against which the braking spring presses. The intermediate member and the braking spring are arranged such that the intermediate member remains stationary and non-rotating during normal operation. The intermediate member has a lateral surface and a supporting surface, the lateral surface presses against the circumferential surface of the arbor, and the braking spring applies a total pressing force towards the arbor against the supporting surface so as to generate a frictional force between the lateral surface and the circumferential surface, and this frictional force generates the braking torque.

[0008] According to a first advantageous alternative embodiment, the intermediate member and the braking spring are configured such that once the display wheel set has been assembled in the movement and the braking device has been fully assembled and adjusted, the pressing force remains constant.

[0009] In a preferred general alternative embodiment, the intermediate member applies only a radial pressure on the arbor of the display wheel set.

[0010] In a main embodiment, the braking spring is a wire spring or a leaf spring, the longitudinal axis of which lies in a geometric plane parallel to the general plane of the movement.

[0011] In a main embodiment, the movement includes an eccentric device, the axis of rotation of which is perpendicular to the geometric plane, and the eccentric device is arranged to radially press against the braking spring so as to be able to change the total radial pressing force exerted by the braking spring on the intermediate member by rotating about its axis of rotation.

[0012] The present utility model also includes the following solutions:

[0013] Solution 1. A mechanical watch movement, comprising: a barrel; an escapement wheel set associated with a mechanical resonator; a display wheel set including an arbor adapted to carry a display member; and a braking device associated with the display wheel set and including a braking spring and an intermediate member disposed between the braking spring and the arbor of the display wheel set, the display wheel set being rotatably drivable by the barrel but not forming part of the transmission mechanism from the barrel to the escapement wheel set, the braking spring being arranged such that once the display wheel set is subjected to a rotational driving torque, a braking torque can be generated on the display wheel set via the intermediate member against which the braking spring presses, characterized in that the intermediate member and the braking spring are arranged such that the intermediate member remains stationary and non-rotating during normal operation; and the intermediate member has a lateral surface and a bearing surface, the lateral surface presses against the circumferential surface of the arbor, and the braking spring applies a total pressing force against the bearing surface to the arbor so as to generate a frictional force between the lateral surface and the circumferential surface, and the frictional force generates the braking torque.

[0014] Solution 2. The mechanical watch movement according to Solution 1, characterized in that the intermediate member is configured to apply only a radial pressure on the arbor of the display wheel set.

[0015] Solution 3. The mechanical watch movement according to Solution 1 or 2, wherein the arbor defines a central axis, characterized in that the circumferential surface is cylindrical and axial, and the lateral surface is axial.

[0016] Solution 4. The mechanical watch movement according to any one of the foregoing solutions, wherein the braking spring is a wire spring or a leaf spring, and the longitudinal axis thereof lies in a geometric plane parallel to the general plane of the movement.

[0017] Solution 5. The mechanical watch movement according to Solution 4, wherein the braking spring is arranged such that the middle part of the braking spring exerts the pressing force on the bearing surface of the middle member; and two end parts of the braking spring located on both sides of the middle part are pressed by two remote parts of the watch movement, such that the middle part exerts the pressing force on the bearing surface.

[0018] Solution 6. The mechanical watch movement according to Solution 5, wherein the braking spring is not fastened to the watch movement, but is held in a tensioned state by the remote parts of the watch movement, and the two end parts of the braking spring press against the remote parts in two directions in the geometric plane.

[0019] Solution 7. The mechanical watch movement according to Solution 6, wherein the middle member and the braking spring are configured such that their relative positioning does not substantially change over time, even in the case where the braking spring may undergo a longitudinal displacement due to the acceleration experienced by the movement in its general plane.

[0020] Solution 8. The mechanical watch movement according to any one of Solutions 5 to 7, wherein the movement includes an eccentric device, the axis of rotation of the eccentric device being perpendicular to the geometric plane, and the eccentric device is arranged to press against the braking spring so as to be able to change the pressing force exerted by the braking spring on the middle member by rotating about its axis of rotation.

[0021] Solution 9. The mechanical watch movement according to any one of the foregoing solutions, wherein the middle member is a washer having a central opening, the arbor of the display wheel set passes through the central opening, and the lateral surface of the washer is defined by the cylindrical surface of its central opening.

[0022] Solution 10. The mechanical watch movement according to Solution 9, wherein the washer has a groove on its periphery, the groove defines the bearing surface, and at least a part of the braking spring that exerts the pressing force in the direction of the arbor is at least partially inserted into the groove.

[0023] Solution 11. The mechanical watch movement according to any one of the foregoing solutions, characterized in that the intermediate member is arranged on a support, the support having an abutment surface at the periphery of this intermediate member, the abutment surface being positioned horizontally towards the intermediate member and diametrically opposite to the support surface, such that before assembling the display wheel set, the intermediate member and the brake spring can be pre-assembled in the mechanical watch movement, wherein the intermediate member abuts against the abutment surface.

[0024] Solution 12. The mechanical watch movement according to Solution 11, characterized in that the abutment surface is arranged such that, after the pre-assembly of the intermediate member and the brake spring, the central cylindrical opening in the intermediate member has at least one region overlapping with the central cylindrical opening in a tube or pipe, the tube or pipe being rotatable or fixed, and a part of the arbor of the display wheel set is inserted into the at least one region, such that when the display wheel set is installed in the mechanical watch movement, the arbor can pass through two central circular openings without initially applying a radial force on the intermediate member.

[0025] Solution 13. The mechanical watch movement according to any one of the foregoing solutions, characterized in that at least a part of the arbor defining the rotary surface is made of steel or composed of a copper alloy, and at least a part of the intermediate member defining the lateral surface is composed of a copper alloy or steel, respectively.

[0026] Solution 14. The mechanical watch movement according to any one of Solutions 1 to 12, characterized in that at least a part of the arbor defining the rotary surface is made of steel or composed of a copper alloy, and at least a part of the intermediate member defining the lateral surface is composed of a polymer.

[0027] Solution 15. The mechanical watch movement according to any one of Solutions 1 to 12, characterized in that at least a part of the arbor defining the rotary surface is made of steel or composed of a copper alloy, and at least a part of the intermediate member defining the lateral surface is composed of a ceramic, especially ruby or zirconia, or composed of a material containing gold or nickel, and forms an outer layer at least partially covering the intermediate member. Description of the Drawings

[0028] The present utility model will be described in more detail hereinafter with reference to the drawings given by way of non-limiting examples, in which:

[0029] Figure 1is a partial perspective view of a main embodiment of a mechanical watch movement according to the present invention, showing a braking device according to the present invention, which is pre-mounted in a preliminary step before assembling the timer wheel set for which the braking device is intended;

[0030] Figure 2 is Figure 1 a plan view of a part of the mechanical watch movement shown in;

[0031] Figure 3 is a sectional view along Figure 2 the central axis of a tube designed to receive a part of the arbor of the timer wheel set, taken through the cutting plane III-III in;

[0032] Figure 4 is a bottom view of the mechanical watch movement in the main embodiment after the timer wheel set has been assembled;

[0033] Figure 5 is a partial sectional view of the mechanical watch movement along Figure 4 the cutting plane V-V in;

[0034] Figure 6 is a partial view diagrammatically showing a specific alternative embodiment of the main embodiment; and

[0035] Figure 7A and Figure 7B are partial views diagrammatically showing two advantageous alternative embodiments of the main embodiment;

[0036] Figure 8 is a partial view diagrammatically showing a specific alternative embodiment of the main embodiment of the present invention; and

[0037] Figure 9 is a partial view diagrammatically showing a second embodiment of the present invention. Detailed Description

[0038] The following will refer to Figures 1 to 5 to describe a main embodiment of a mechanical watch movement 2 according to the present invention.

[0039] The mechanical watch movement 2 includes:

[0040] - a barrel,

[0041] - an escapement wheel set 58, which is associated with a mechanical resonator (not shown in the drawings),

[0042] - The first wheel set 30, which forms the display wheel set and is intended to carry the display member, in particular the hand 48 of the timepiece function second display device, and is rotatably driven by a second wheel set 52 included in the transmission mechanism from the barrel to the escapement wheel set, and this first wheel set is not included in this transmission mechanism.

[0043] - The braking spring 10, which is arranged so as to be able to generate a braking torque on this first wheel set intended to prevent the display member 48 from vibrating once the first wheel set 30 is subjected to a rotational driving torque, and a permanent radial force for holding the display member in a stable position when the display member is stationary.

[0044] According to the present utility model, the mechanical watch movement 2 includes a braking device 6 that acts on the display wheel set and includes a braking spring 10 and an intermediate member 8 arranged between this braking spring and the arbor 36 of the first wheel set 30. The braking spring is arranged so as to be able to generate a braking torque on the display wheel set via the intermediate member against which this braking spring bears. For this purpose, the intermediate member has a lateral surface 9 and a bearing surface 25, the lateral surface 9 bears against the circumferential surface 35 of the arbor, and the braking spring applies a total pressing force in the direction of the arbor against the bearing surface 25 so as to generate a frictional force between this lateral surface and the circumferential surface, and this frictional force generates the braking torque. Thus, the braking spring applies a braking torque on the first wheel set / display wheel set via the intermediate member against which the braking spring bears. The intermediate member 8 and the braking spring 10 are arranged such that the intermediate member remains stationary and non-rotating during normal operation. The arbor 36 of the first wheel set and the intermediate member are configured such that the circumferential surface 35 of the arbor can slide on the lateral surface 9 while being subjected to a dynamic frictional force that generates the braking torque. Before the circumferential surface slides on the lateral surface, a static frictional force generates the braking torque and thus holds the arbor stationary.

[0045] Preferably, the intermediate member 8 applies a radial pressure only on the arbor 36 of the first wheel set 30. According to an advantageous feature, the brake spring 10 applies only a total radial pressing force on the intermediate member. The support surface 25 is opposite the lateral surface 9, i.e., the support surface is located on the other side of the intermediate member 8 opposite the side defining the lateral surface 9 of this intermediate member. This alternative embodiment is advantageous because the braking device abuts against an undercut portion with a small radial play variation, and thus gives a constant braking torque for a given frictional force between the rotary surface 35 and the lateral surface 9. In the advantageous alternative embodiment shown in the drawings, the rotary surface 35 of the arbor 36 is cylindrical and axial, and the lateral surface 9 of the intermediate member is axial, i.e., the cylindrical rotary surface 35 and the lateral surface 9 are oriented along the axis of rotation 42 of the first wheel set 30, and the axis of rotation 42 coincides with the central axis of the arbor 36. Thus, the lateral surface 9 and the cylindrical rotary surface 35 are parallel to this axis of rotation 42. In a preferred alternative embodiment, the intermediate member 8 and the brake spring 10 are configured such that the pressing force remains constant once the wheel set is assembled in the movement and the braking device is fully assembled and adjusted.

[0046] According to a main alternative embodiment, the brake spring 10 is a wire spring or a leaf spring whose longitudinal axis lies in a geometric plane parallel to the general plane 50 of the mechanical watch movement 2.

[0047] According to the alternative embodiment shown, the intermediate member 8 is a washer having a central cylindrical opening in which the arbor 36 of the first wheel set 30 would freely slide and rotate in the absence of any interaction from the brake spring 10, and the lateral surface 9 of this washer is defined by the cylindrical surface of its central cylindrical opening, which cylindrical surface is preferably circular (i.e., a rotary surface).

[0048] According to a particular alternative embodiment, the washer has a circular groove 24 in its periphery, the circular groove 24 defining the support surface 25, and at least a part of the brake spring 10 applying the radial pressing force is at least partially inserted into the circular groove 24. In particular, the groove 24 has a V-shaped cross-section, and the brake spring 10 is a wire spring having a circular cross-section, as Figure 3 and Figure 5 shown. This arrangement allows the brake spring to be axially positioned in contact with the washer in its middle part. Thus, the spring cannot move freely axially.

[0049] By way of non-limiting example, in a first alternative embodiment, when at least the part of the shank defining the rotary surface 35 is made of steel, at least the part of the washer defining its central cylindrical opening is made of a copper-beryllium (CuBe) alloy, or vice versa. This first alternative embodiment gives good tribological results. In a second alternative embodiment in which the said part of the shank is made of steel or CuBe, at least the part of the washer defining its central cylindrical opening is made of a polymer. Preferably, the entire washer is made of a polymer. This second alternative embodiment is particularly advantageous for self-lubrication. In other alternative embodiments in which the shank is made of steel or a copper alloy (such as CuBe or brass), at least the part of the washer defining its central cylindrical opening is made of bronze, nickel or gold, particularly in the case of nickel or gold in the form of a thin layer deposited on a substrate of another material, or more generally of a metal alloy containing gold or nickel. In other alternative embodiments, at least the part of the washer defining its central cylindrical opening is made of a ceramic, particularly ruby or zirconia.

[0050] It should be noted that the material of the braking spring can be selected in such a way as to optimize the elastic properties of this spring and its manufacture, without having to worry about problems of friction and wear, since the washer, and more generally the intermediate part, is intended to be static during the normal operation of the mechanical watch movement, i.e., stationary and not rotating. In the case of the washer, in order to prevent it from rotating, changes can be made to the shape of the intermediate part and / or the shape of the braking spring, as will be explained in more detail below, or, particularly in the case of the washer, changes can be made to the material used to make the spring and at least the external part of the intermediate part in contact with the spring and / or the surface treatment applied to these parts in order to obtain a high frictional force between the braking spring and the intermediate part.

[0051] According to another preferred alternative embodiment, the braking spring 10 is arranged in the mechanical watch movement 2 in such a way that the intermediate part between its two end parts presses radially against the bearing surface 25 of the intermediate part 8 / washer. More specifically, the braking spring 10 is arranged so that the intermediate part of this braking spring exerts the said pressing force on the bearing surface 25 of the intermediate part / washer. For this purpose, the two end parts of the braking spring, located respectively on either side of the said intermediate part, are pressed by the first remote part 16 and the second remote part 20 of the watch movement, so that this intermediate part exerts a pressing force on the bearing surface of the intermediate part / washer. This configuration of the braking device is advantageous because it allows the braking spring to continuously press against the bearing surface of the intermediate part / washer. In addition, this configuration is less sensitive to vibrations and shocks than in the case where the braking spring has an anchoring point at one end and a contact point at the other end.

[0052] In a particular alternative embodiment, the brake spring 10 is bent in its middle part, and the bearing surface 25 of the intermediate member 8 / washer has a convex curvature in said geometric plane relative to the arbor 36 of the first wheel set 30, and in particular a circular curvature in the case of the washer. In the first alternative embodiment, the middle part of the brake spring follows this circular curvature along the bearing surface. In the second alternative embodiment, the radius of curvature of the middle part is less than the mean radius of curvature of the bearing surface, such that the brake spring bears against the intermediate member / washer at "two points" of the bearing surface (i.e., at two separate locations). It should be noted that for a substantially V-shaped groove, a spring with a circular cross-section is locally compressed at a pair of axially aligned points. Thus, in such a configuration of the groove and the brake spring, the brake spring bears at two pairs of points that are angularly spaced from each other (where each pair of points is axially aligned), and thus at "two points" projected in the total plane of the spring parallel to the total plane 50 of the movement. Finally, these alternative embodiments do not exclude other advantageous alternative embodiments such as: where the mean radius of curvature of the middle part is greater than the radius of curvature of the bearing surface, resulting in a radial pressure being exerted at "one point" (i.e., at a pair of points axially aligned, but at a single point projected in the total plane of the spring / the total plane 50 of the movement).

[0053] According to an advantageous alternative embodiment, as Figure 2 shown, the brake spring 10 is not fastened to the movement by a specific component, but is held in tension by the first remote part 16 and the second remote part 20 of this movement. Two end parts of the brake spring, which are respectively located on both sides of the middle part of this brake spring, bear against the first remote part 16 and the second remote part 20, and this brake spring bears radially against the intermediate member 8, which is in particular a washer. The direction of the forces exerted by the first remote part 16 and the second remote part 20 on the spring is opposite to the direction of the reaction force of the intermediate member 8 / washer on the middle part of the spring. These forces exerted on the brake spring in the geometric plane in which the longitudinal axis of the brake spring lies (a horizontal plane orthogonal to the rotation axis 42 whose central axis coincides with the arbor 36) generate stresses that hold the brake spring in place. Then, to prevent the spring from moving axially / vertically, and in particular to prevent its middle part from slipping out of the groove 24, two parts of the support 4 are respectively provided on each of the two said sides, and these parts define the lower axial stop of the brake spring. On the first side, a groove 14 is provided in the support 4 (barrel arbor) of the braking device, and this support can support the washer, especially when assembling the washer before installing the spring. The bottom of this groove, which forms a thin horizontal wall, provides a lower limit for any possible displacement of the part of the spring located on this side. On the second side, the brake spring is partially located above the small projection 18.

[0054] In Figure 6 , Figure 7A and Figure 7B various other advantageous alternative embodiments are shown diagrammatically. Figure 6 The alternative embodiment shown in Figures 7A to 7B is characterized in that the middle part of the brake spring 10A has two bends 71 and 72, which are separated by a straight section 70 (stress-free), and the straight section 70 abuts against the circular washer substantially at its middle. This ensures that the brake spring 10A always abuts against the washer at "one point". Figure 7A The alternative embodiment of Figure 7B is characterized by an intermediate member 68 which is not circular but is formed by a truncated washer having a straight region 80. In the alternative embodiment shown in Figure 7A , the brake spring 10 has a bend 74 in its middle part, and the bend 74 is positioned facing the straight region 80 of the truncated washer 68. In the alternative embodiment shown in Figure 7B , the spring 11 is straight / linear without stress and when it is tensioned to press against the intermediate member, it is slightly bent (concave curvature when viewed from the intermediate member), such that it presses against both ends of the straight region 80 of this intermediate member. Thus, in the alternative embodiments of Figure 7B and Figure 7A , the brake spring 10 or 11 respectively exerts two forces F1 and F2 at both ends of the straight region 80. The two forces F1 and F2 are overall radial, i.e., their sum at the midpoint is radial. However, each of these two forces exerts a moment on the intermediate member 68, such that when the spring moves longitudinally and one of the two forces F1 and F2 decreases relative to the other, the intermediate member 68 automatically undergoes a small rotation in order to re-establish equilibrium between the two opposing moments applied thereto. Figure 7A and Figure 7B The alternative embodiments shown in

[0055] always provide support at "two points" projected in the geometric plane of the spring. Figure 8 A specific alternative embodiment is shown diagrammatically in Figure 6As in the embodiment, this alternative embodiment is designed to ensure that the braking spring 10B is always pressed at "a point" on the intermediate member 78, which has an integral square shape with rounded corners. The braking spring 10B has a bend 76 such that the two straight portions of the spring on either side of the bend are at an angle greater than 90°, but relatively close to that value, for example an angle equal to 110°. One of the rounded corners of the intermediate member is positioned in the bend 76 of the spring, and when the spring and the intermediate member 78 are stationary, the spring exerts a substantially radial force F on the intermediate member. If the spring 10B moves, especially due to an impact, the direction of the force changes such that the intermediate member then experiences a moment that causes it to rotate. This ensures that the same angle of the square intermediate member is always maintained in the bend 76 of the braking spring, and the pressure is applied at "a point". Additionally, in normal operation (when the braking spring is stationary), this alternative embodiment keeps the intermediate member stationary (non-rotating), thus ensuring a constant and clearly defined braking torque on the arbor of the wheel set.

[0056] According to a preferred alternative embodiment of the present utility model, the braking device 6 includes an eccentric device (second remote portion 20), the rotational axis of the eccentric device being perpendicular to the general plane 50 and thus parallel to the central axis / rotational axis 42 of the wheel set 30, and the eccentric device being arranged to radially press against the braking spring so as to be able to change the said radial pressing force exerted by the braking spring on the intermediate member / washer by rotating about its rotational axis. In Figure 1 and Figure 2 the advantageous alternative embodiment shown, the eccentric device forms one of the two components that keeps the braking spring in a tensioned state. Thus, by rotating the eccentric device, the stress on this spring is changed, and thereby the braking torque applied to the first wheel set 30 (timer wheel set) when the first wheel set 30 (timer wheel set) is subjected to a rotational drive torque can be adjusted. This configuration is advantageous because it is insensitive to vibrations and impacts. In another alternative embodiment, another device for adjusting the radial force is provided, especially a device equipped with a pressing member capable of linear movement.

[0057] Figure 9Shows another embodiment of the present invention, in which the braking spring 11 is straight (without stress). This spring is rigidly fastened at one of its ends in the fixed part 82 and cannot change the angular position of the fixed part 82 in the geometric plane, thus preventing any involuntary displacement or displacement caused by impact. The groove in the part 82 into which the end of the spring 11 is inserted is oriented such that the middle region of the spring exerts a radial pressing force F on the washer, and this spring has a first convex curvature (when viewed from the washer) between the fastening part 82 and the support point of the spring on the washer. Preferably, at the other end of the spring, an eccentric device is provided to adjust the radial force F. In this embodiment, the eccentric device is located on the same side of the braking spring as the washer, and the washer forms an intermediate part between the braking spring and the arbor of the associated wheel set. Therefore, the braking spring 11 also has a second convex curvature between the said support point and the eccentric device, and this second curvature is less than the first curvature because the radial force F is not zero. It should be noted that Figure 9 The alternative embodiment shown in defines a type of construction with a single support point, that is, according to the definition given above, the braking spring is supported on the washer at "one point". In another alternative embodiment of the "two points" type, a star-shaped intermediate part is provided, for example having four to six tips, each tip having a small rounded part. The slightly convex braking spring always supports on two tips of the star-shaped intermediate part, thus exerting two forces, which form a radial total pressing force at their center point. In other words, these two forces produce two opposite torques of equal strength on the intermediate part. It should also be noted that in the case of impact, the control of the braking device cannot be released.

[0058] Figures 1 to 3 Shows a mechanical watch movement 2, in which the braking device 6 is pre-assembled in a preliminary step before assembling the first wheel set 30. This preliminary assembly of the braking device 6 is advantageous. This is made possible in particular due to the fact that the force exerted by the braking spring is radial, and the washer is provided above the pinion and the wheel 32 forming the first wheel set, and above the reset heart piece 34 in the shown example where the first wheel set is a timer wheel set. Figure 4 and Figure 5 Shows the mechanical watch movement 2 after the first wheel set 30 has been installed in this movement and the braking device is in an operating state.

[0059] To allow the preliminary assembly of the braking device 6, the washer is arranged on the support 4 (barrel arbor), and the support 4 has an abutment surface 26 on the periphery of this washer. The abutment surface 26 is positioned horizontally facing the washer and is diametrically opposite to the said support surface 25, so that the washer and the braking spring 10 can be pre-assembled in the mechanical watch movement 2 before assembling the first wheel set 30, where the washer abuts against the abutment surface 26, asFigures 1 to 3 As shown. The adjacent surface 26 is defined by the lateral surface of the cavity 12 machined in the support 4, in which the washer is arranged, and the cavity 12 opens on the lower side of the movement (by definition, the analog display is on the upper side).

[0060] In a preferred alternative embodiment, the adjacent surface 26 is arranged such that after the pre-assembly of the washer and the brake spring 10, the central cylindrical opening in the washer has at least one area overlapping with the central circular opening in the tube or pipe 44, and then a part of the arbor 36 of the first wheel train 30 (timekeeping wheel train) is inserted into the at least one area, so that when the first wheel train is installed in the mechanical watch movement 2, the arbor can pass through the two central circular openings without initially applying a radial force on the washer. As Figure 3 As can be seen, in the illustrated alternative embodiment, the central cylindrical opening in the washer completely overlaps the central circular opening in the tube 44. It should be noted that in the illustrated example, the arbor 36 of the first wheel train 30 is inserted into the tube 44, and the arbor carries the display pointer and is thus rotatable, and this tube pivots in the plate 60 and the barrel rod 4. The inner bearing 46 is arranged inside the central opening in the tube, where the inner bearing pivots on the end portion 37 of the arbor 36 on which the timekeeping pointer 48 is mounted, and the maximum diameter of this end portion is smaller than the diameter of the rotating surface 35, which is particularly cylindrical and axial and finally located inside the central cylindrical opening 9 in the washer. In particular, when assembling the timekeeping wheel train, this facilitates the insertion of the arbor 36 into the two central circular openings when the initial overlap of the two central circular openings before the assembly of this timekeeping wheel train is only partial.

[0061] Once installed, in the illustrated embodiment, the first wheel train 30 forming the timer wheel train pivots through the upper bearing 46 and the lower bearing 38 in the opening arranged in the rod 40, and the washer no longer abuts against the side wall 26 of the cavity 12 of the support 4, but abuts against the arbor 36 of the first wheel train via its central cylindrical opening, more precisely, against the rotating surface 35 of this arbor, which is advantageously cylindrical and axial. It should be noted that in the illustrated alternative embodiment, the barrel pivots between the barrel rod 4 forming the support part of the washer and the plate 60. The first wheel train is sometimes rotatably driven by the second wheel train 52 via the clutch wheel 54 mounted on the operating lever 56 according to a command, and the operating lever 56 is conventionally controlled by a column wheel or a cam ( Figure 4 disengagement as shown by the arrow in). The second wheel train 52 includes a driving wheel, which is included in the transmission mechanism from the barrel to the escapement wheel 58. Here, this driving wheel forms the small seconds wheel of the time display device of the watch incorporating the mechanical watch movement 2.

[0062] The present invention has been described in detail with respect to the timer wheel set 30, but the braking device of the present invention can be provided for other wheel sets of a mechanical watch movement, in particular for a small second wheel set when this wheel set is not included in the transmission mechanism from the barrel to the escapement wheel 58.

[0063] The present invention has several advantages, some of which have been described. The braking device 6 includes an eccentric device that makes it easy to adjust the radial pressing force exerted by the braking spring on the intermediate member 8 / washer, and adjusts the moment of the frictional force applied to this first wheel set via this radial force applied to the arbor 36 of the first wheel set 30. Once the braking device has been fully installed in the mechanical watch movement, the eccentric device allows adjustment of the braking torque without having to remove the braking spring in order to slightly modify its initial shape. Assuming that there is a washer between the braking spring 10 and the arbor 36, and apart from the fact that the forces involved are intended to be radial, the assembly of the timing pointer 48 on the first wheel set 30, and in particular its removal (for example when replacing this pointer 48, or when cleaning the mechanical watch movement) cannot damage the braking spring, which is a precision element in the braking device 6, the washer is more robust and can withstand a certain amount of axial pressure against the support 4.

[0064] The braking device 6 is protected against stresses that may damage the braking device 6 during the assembly of other components of the mechanical watch movement, in particular during the assembly of the timing wheel set 30. When the watch movement is removed, and in particular when the first wheel set 30 is removed, the braking device 6 can remain in place without changing its settings.

[0065] The braking device according to the present invention makes it possible to relatively precisely pre-determine the moment of the frictional force because the height of the lateral surface 9 of the intermediate member 8, in particular the washer, is much greater than the height of the braking spring, because the material of the intermediate member 8 / washer can be selected, and because the diameter of the rotary surface that defines the cylindrical and axial surface of the arbor 36 against which the intermediate member 8 / washer abuts is precisely determined.

Claims

1. A mechanical watch movement (2), comprising: barrel; an escape wheel assembly (58) associated with a mechanical resonator; A display wheel set (30) comprising a stem (36) intended to carry a display member (48); and a braking device (6) associated with the display wheel set and comprising a brake spring (10, 10A, 10B, 11) and an intermediate part arranged between the brake spring and the stem of the display wheel set, this display wheel set being rotatably driven by the barrel but not forming part of the transmission mechanism from the barrel to the escapement wheel set, the brake spring being arranged so as to brake once this display wheel set is subjected to a rotational drive torque. The intermediate component, which is pressed by the brake spring, is capable of generating a braking torque on the display wheel set, and is characterized in that the intermediate component and the brake spring are arranged so that the intermediate component remains stationary and does not rotate during normal operation; and the intermediate component has a lateral surface (9) and a supporting surface (25), the lateral surface (9) being pressed against the rotating surface (35) of the stem, and the brake spring applies a total clamping force to the stem against the supporting surface (25) so as to generate a friction force between the lateral surface and the rotating surface, and the friction force generates the braking torque.

2. The mechanical watch movement according to claim 1, characterized in that: The middle part is configured to exert radial pressure only on the stem (36) of the display wheel set (30).

3. A mechanical timepiece movement according to claim 2, wherein the stem defines a central axis (42), characterized in that The surface of revolution (35) is cylindrical and axial, and the lateral surface (9) is axial.

4. A mechanical watch movement according to any one of claims 1 to 3, characterized in that: The brake spring (10, 10A, 10B, 11) is a wire spring or a leaf spring, the longitudinal axis of which lies in a geometric plane parallel to the general plane (50) of the mechanical timepiece movement.

5. The mechanical watch movement according to claim 4, characterized in that: The brake spring (10, 10A, 10B, 11) is arranged so that the middle part of the brake spring applies the pressing force on the supporting surface of the middle part; and the two end parts of the brake spring, respectively located on both sides of the middle part, are pressed by two distant parts of the watch movement so that the middle part applies the pressing force on the supporting surface.

6. The mechanical watch movement according to claim 5, characterized in that: The brake spring (10, 10A, 10B) is not fastened to the mechanical timepiece movement, but is held in tension by the remote part of the mechanical timepiece movement, the two end portions of the brake spring being pressed against the remote part in both directions in the geometrical plane.

7. The mechanical watch movement according to claim 6, characterized in that: The middle part and the brake spring are configured so that their relative positioning does not vary over time, even in the event of a possible longitudinal displacement of the brake spring due to accelerations to which the mechanical timepiece movement is subjected in its general plane.

8. A mechanical watch movement according to any one of claims 5 to 7, characterized in that: This mechanical timepiece movement comprises an eccentric device, the rotation axis of which is perpendicular to the geometrical plane and is arranged to press against the brake spring (10, 10A, 10B, 11) so as to be able to change the pressing force exerted by the brake spring on the middle part by rotating about its rotation axis.

9. A mechanical watch movement according to any one of claims 1 to 3, characterized in that: The middle part (8) is a washer having a central opening through which the stem (36) of the display wheel set passes, the lateral surface (9) of this washer being defined by the cylindrical surface of its central opening.

10. The mechanical watch movement according to claim 9, characterized in that: The washer has a groove (24) on its periphery which defines the bearing surface (25) and into which a portion of the brake spring (10) which applies the pressing force in the direction of the stem is at least partially inserted.

11. A mechanical watch movement according to any one of claims 1 to 3, characterized in that: The middle part is arranged on a support (4) which has, at the periphery of this middle part, an abutment surface (26) positioned horizontally facing the middle part and diametrically opposite the bearing surface (25), so that the middle part and the brake spring can be preassembled in the mechanical timepiece movement before assembling the display wheel set (30), with the middle part abutting against the abutment surface.

12. The mechanical watch movement according to claim 11, characterized in that: The abutment surface (26) is arranged so that, after pre-assembly of the middle part and the brake spring (10), the central cylindrical opening in the middle part has at least one area overlapping with a central circular opening in a tube (44) or a pipe, the tube (44) or the pipe being rotatable or fixed, into which at least one area a portion of the stem (36) of the display wheel set (30) is inserted, so that when the display wheel set is mounted in the mechanical timepiece movement, the stem can penetrate the two central circular openings without having to initially exert a radial force on the middle part.

13. A mechanical watch movement according to any one of claims 1 to 3, characterized in that: At least a portion of the stem (36) defining the revolving surface (35) is made of steel or of a copper alloy, and at least a portion of the intermediate part defining the lateral surface (9) is made of a copper alloy or of steel, respectively.

14. A mechanical timepiece movement according to any one of claims 1 to 3, characterized in that At least a portion of the stem (36) defining the revolving surface (35) is made of steel, or consists of a copper alloy, and at least a portion of the intermediate part defining the lateral surface (9) consists of a polymer.

15. A mechanical timepiece movement according to any one of claims 1 to 3, characterized in that: At least a portion of the stem (36) defining the revolving surface (35) is made of steel or a copper alloy, and at least a portion of the intermediate part defining the lateral surface (9) is made of ceramic or a material containing gold or nickel and forms an outer layer that at least partially covers the intermediate part.

16. The mechanical watch movement according to claim 15, characterized in that: At least a portion of said middle part defining said lateral surface (9) is made of ruby ​​or zirconium oxide.

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