Clock striking mechanism

Abstract

This reduces the risk of hammer rebound after striking the gong without significantly reducing the energy efficiency of the striking device. [Solution] The hammer 11 includes a resonator 12 and a hammer 11 which includes a first part 21 and a second part 22 assembled by a pivot connection so as to be able to pivot relative to each other around a rotation axis 30, and which holds a first permanent magnet 26 and a second permanent magnet 27 between these two parts, forming a magnetic return system. The permanent magnets are arranged to generate an attractive force between them which pulls the first part and the second part toward a stable configuration of the hammer. During a strike, the first part, referred to as the drive unit 21, stops when it strikes a fixed stopper 24 before the second part, referred to as the striking unit 22, reaches the resonator, also referred to as the “gong”, the striking unit continues to rotate toward the gong to complete the strike, and then returns to the drive unit to finally occupy a stationary position away from the gong.

Description

Technical Field

[0001] The present invention relates to a striking mechanism for a clock.

Background Art

[0002] Attached FIGS. 1 and 2 are two partial views of a conventional striking mechanism. These figures show a resonator composed of a hammer 4 and a gong 5, a first return means composed of a preload spring 6, a fixed stopper 7, and a second return means composed of an elastic pin 8. The pin 8 is fixed to the hammer, and its elasticity is relatively low so as to limit the rebound (rebound) and, if possible, prevent such a rebound. Since the operation of such a striking mechanism is known to those skilled in the art, only its main features will be outlined below.

[0003] The hammer 4 is attached so as to pivot around a fixed shaft 9 and has a beak 10 for striking the gong. The preload spring 6 is arranged so as to be permanently pressed against the elastic pin 8, whereby the spring 6 permanently returns the hammer 4 towards the gong 5. FIGS. 1 and 2 show the striking mechanism in a stable configuration where the hammer is in the rest position. As can be seen, in this position, the hammer 4 abuts against the fixed stopper 7 via the elastic pin 8, and the beak 10 and the gong 5 are separated by a small gap (FIG. 1). The width of the small gap separating the gong and the hammer when the hammer is in the rest position is referred to as the "safety distance". When the hammer 4 is in the rest position, the reaction force exerted by the fixed stopper 7 balances the force generated by the preload spring 6. Therefore, the rest position is a stable position.

[0004] When the mechanism is in the winding-up phase, a striking mechanism (not shown as it is known) lifts the hammer 4 against the force exerted by the preload spring 6. During this movement, the beak 10 moves away from the gong 5 gradually, and at the same time the pin 8 moves away from the fixed stopper 7.

[0005] When the striking mechanism is released, the mechanism releases the hammer. The hammer is then struck by the preload spring 6 and pivots rapidly toward the gong. A flexible pin 8 is fixed to the hammer, and the mechanism is configured such that this pin strikes a fixed stopper 7 before the beak 10 reaches the gong. However, since the pin 8 is elastic, and the hammer 4 has considerable kinetic energy when the pin contacts the fixed stopper 7, the hammer does not come to a sudden stop by the fixed stopper, but rather continues its movement, moves beyond the resting position and finally strikes the gong 5, and is strongly braked by the fixed stopper on the path between the resting position and the gong-striking position. Thus, it is understood that the hammer is able to strike the gong due to the deformation of the elastic pin 8. After the impact on the gong, some of the energy is transferred to the gong and returned to the hammer (partial elastic impact), thereby allowing the hammer to return to a stable position a certain distance from the gong. The elastic energy released by the elastic pin 8 returning to its unstressed shape is also added to the energy released by the gong. Therefore, it is understood that the elastic pin functions particularly as a second return mechanism, and the force it exerts, against the force of the preload spring 6, keeps the hammer beak 10 away from the resonator 5 when the hammer is in the resting position. Thus, the preload spring 6, the fixed stopper 7, and the flexible pin 8 together define the stable / resting position of the hammer.

[0006] The aforementioned prior art mechanism has certain drawbacks. In particular, because some of the hammer's kinetic energy is used to deform the elastic pin, the hammer slows down before striking the gong. Understandably, such a mechanism limits the energy efficiency of the striking action. One possible solution to this problem is to move the fixed stopper closer to the gong. This modification reduces the distance the hammer must travel beyond the fixed stopper, thereby limiting the strain on the elastic stopper. However, reducing the kinetic energy lost to the elastic pin as the hammer pivots from its resting position to the gong also increases the probability of the hammer rebounding after each strike. Such rebounds are undesirable. In fact, it is known that this often hinders the gong from oscillating freely. Therefore, designers of striking mechanisms must find a compromise between energy efficiency on the one hand and a sufficient safety distance between the hammer and the gong in the resting position on the other. This requires tight tolerances in the design, complex assembly, and adjustment of the safety position, which is difficult and time-consuming even for experienced watchmakers.

[0007] Patent Document 1 provides one solution to the above-mentioned problem. This prior art document describes a striking mechanism that incorporates many features of the more conventional striking mechanisms described above. The main difference between the striking mechanism described in Patent Document 1 and the mechanism described above is that the hammer is not integrally molded, but instead includes a first part and a second part connected to each other by a hinge, with the first part rotatably mounted relative to the second part. The first part of the hammer includes a striking beak (or striking zone) for striking the gong, while the second part is positioned to pivot around a fixed axis of the striking mechanism and is subjected to the driving force of a preload spring. Thus, the first part forms the striking part, while the second part forms the driving part and defines the resting position of the hammer. The hammer is rotatably arranged between a stable configuration in which the first part abuts against a stopper zone in the second part, and a striking configuration in which the first part moves away from the stopper zone as the tension of the connecting spring increases, causing the striking beak to move closer to the gong. Specifically, the hammer includes an arc-shaped leaf spring. One end of the leaf spring is fixed to the first part, and the other end abuts against a part of the second part. The leaf spring is pre-tensioned to permanently return the first and second parts of the hammer to the first stable configuration in which the hammer is stationary.

[0008] When the striking mechanism is stationary or in the winding phase, the hammer is in its stable configuration. When the striking action is released at a given moment, the mechanism abruptly releases the hammer; that is, it abruptly releases the second part on which the hammer loading and release mechanism acts. This allows the entire hammer to pivot rapidly toward the gong without changing its configuration. During the pivot, the mechanism is positioned so that the second part of the hammer contacts a fixed stopper attached to the support of the mechanism before the striking beak of the first part reaches the gong. The second part of the hammer is abruptly stopped by the fixed stopper. However, due to the articulation and connecting spring between the first and second parts of the hammer, the first part is allowed to continue moving independently, transitioning into a striking configuration and finally striking the gong.

[0009] The pivoting of the first part of the hammer around the hinge, resisting the restorative force exerted by the leaf spring, temporarily alters the hammer's configuration. Subsequently, after the impact on the gong, the gong releases some of the energy it received, thereby allowing the first part of the hammer to return to its stable configuration. The elastic energy associated with the restorative force exerted by the leaf spring is added to the energy released by the gong. Thus, according to Patent Document 1, it is understood that the leaf spring functions as a second restorative means.

[0010] While the striking mechanism described in Patent Document 1 has advantages, it also has certain drawbacks. Indeed, as the authors of this specification acknowledge, the use of a hammer consisting of two jointed parts connected by a spring facilitates the positioning of a fixed stopper relative to the gong, and in particular allows the striking beak to be moved further away from the gong in its stationary position while ensuring that the gong is struck by this beak. However, the features of the described striking mechanism do not allow for the deductive elimination of rebound phenomena that adversely affect the quality of the sound emitted from the clock, as will be explained later. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] European Patent No. 2048548 [Overview of the Initiative]

[0012] One of the main objectives of the present invention is to overcome the drawbacks of the prior art described above, and in particular to reduce the risk of hammer rebound after striking the gong without significantly reducing the energy efficiency of the striking device. The present invention achieves this objective and other objectives by providing a striking mechanism according to the appended claim 1.

[0013] The striking mechanism is arranged such that when the hammer is in a stable configuration and its drive unit strikes a fixed stopper while rotating in a first direction, the kinetic energy of the striking part drives the striking part toward a resonator against a second return means across the angular path of the striking part relative to the drive unit. The hammer then temporarily leaves the stable configuration. According to the present invention, the second return means includes two magnetic elements fixedly held by the drive unit and the striking part, respectively. These two magnetic elements are arranged to generate a magnetic force between them that returns the striking part and the drive unit to the stable configuration of the hammer, at least over the initial portion of the angular path.

[0014] In the graph of the attached Figure 6, curves 1 and 2 relate to the first and second embodiments of the present invention, respectively. These will be described in detail later. Curve 3 relates to the striking mechanism described in Patent Document 1, which has already been described. Curve 3 is shown as a comparison to understand at least one important advantage of the present invention. Each curve shows the progression of the return torque exerted by the second return means according to the angle α between the striking part and the drive part, from a situation in which the hammer drive part is held stationary against a fixed stopper while the striking part is approaching the gong to touch the gong at striking position αF.

[0015] The three striking mechanisms corresponding to the three torque curves in Figure 6 are configured such that the energy stored by the prior art elastic system (connecting spring) and in each of the two magnetic systems according to the present invention is substantially identical at the striking position αF, in order to enable a valid comparison. As shown in torque curve 3, in the prior art striking mechanism, the strength of the torque exerted by the second return means (i.e., the connecting spring) increases substantially linearly as the striking part of the hammer moves away from the stable configuration (physical properties of the spring). On the other hand, as shown in torque curves 1 and 2, in the striking mechanism according to the present invention, the strength of the return torque is much greater than that of the prior art mechanism in the initial angular range from the stationary position. In the first embodiment of the present invention, the return force at the stable position can be substantially identical to the return force of a pretensioned connecting spring. Subsequently, in the first embodiment, the return torque reaches a maximum value just before the midpoint (in a particular case), then decreases, becoming relatively weaker near the striking position. In the magnetic system of the second embodiment, the return torque is maximum at the stable stationary position, and then decreases rapidly as it approaches the striking position. The graph in Figure 6 shows angular positions 1a, 2a, and 3a corresponding to 20% of the stored energy at the impact position, and angular positions 1b, 2b, and 3b corresponding to 60% of the stored energy, for each of the three coupling systems corresponding to curves 1, 2, and 3. It can be seen that the energy stored in the coupling system increases very rapidly in the second embodiment and not so rapidly in the first embodiment. However, even in the latter case, the increase in stored energy remains much faster than in the prior art elastic system.

[0016] The striking mechanism, particularly the magnetic coupling system between the drive unit and the striking unit, can be configured such that the residual energy of the striking unit after it strikes the rear stopper of the drive unit during the rebound following the initial strike is equal to approximately 60% of the energy stored in the magnetic coupling system at the striking position. From this, it is understood that the striking mechanism according to the present invention reliably ensures that a full rebound does not occur after the strike, that is, that the striking beak does not touch the gong again after the strike, and in particular, that the striking beak does not touch the gong while it is vibrating as a result of the strike. [Brief explanation of the drawing]

[0017] Other features and advantages of the present invention are given only as non-limiting examples and will become apparent from the following detailed description with reference to the accompanying drawings.

[0018] [Figure 1] Figures 1 and 2 are two partial views, one in plan view and the other in perspective, of the prior art conventional striking mechanism that has already been described. [Figure 2] Figures 1 and 2 are two partial views, one in plan view and the other in perspective, of the prior art conventional striking mechanism that has already been described. [Figure 3] This is a plan view of a first embodiment of the striking mechanism according to the present invention. [Figure 4A] Figures 4A and 4B are front and rear perspective views of the striking mechanism shown in Figure 3. [Figure 4B] Figures 4A and 4B are front and rear perspective views of the striking mechanism shown in Figure 3. [Figure 5] This is a perspective view of a second embodiment of the striking mechanism according to the present invention. [Figure 5A] Figure 5 is a close-up, enlarged view specifically showing the two magnetic elements and the hammer rearward stopping mechanism in the striking mechanism. [Figure 6] This figure shows a curve illustrating the return torque corresponding to the displacement angle of the striking part relative to the drive part, for embodiments of the prior art and two embodiments of the present invention described in detail.

Best Mode for Carrying Out the Invention

[0019] Attached FIGS. 3, 4A, and 4B show a first embodiment of the striking mechanism according to the present invention. The illustrated striking mechanism includes a hammer 11, a resonance body consisting of a gong 12, a first return means consisting of a preload spring 13, and a fixed stopper 14. It is understood that these listed elements are held by a support (not shown). The hammer 11 includes a first part 21 called a driving part and a second part 22 called a striking part. The driving part 21 and the striking part 22 of the hammer are assembled by a pivotal connection. As a result, the driving part 21 and the striking part 22 can rotate relative to each other about a geometric axis 30 defined by the driving part 21. The hinge between part 21 and part 22 is composed of, for example, a tube that passes through the striking part 22 and ends with a small flange that supports the lower end of this striking part. This tube has a head that rests on the driving part and is held in place by a screw 32 screwed into the tube. Note that threads may be formed in the hole for the screw 32 in the driving part, thereby allowing the screw 32 to be screwed into this driving part.

[0020] Most of part 21 and part 22 overlap. The driving part 21 is arranged to pivot about a geometric axis 17 defined by an arbor 16 (material axis) attached to a part of the support of the striking mechanism, and each of the two holes in this part has the two pivot axes. While the driving part 21 is arranged to be rotatable on the support, the striking part 22 is arranged to be rotatable on the driving part. Alternatively, both part 21 and part 22 may be rotatably attached about the same geometric axis fixed to the support. These two parts are rotatable relative to each other over at least a specific angular distance that allows the striking part to strike the gong 12 while the driving part is stopped by the stopper 14 in a first direction of rotational movement towards the gong.

[0021] The preload spring 13 has one end fixed to the support and the other end arranged to permanently bias the drive part 21 clockwise (the first direction) about the shaft 17 (the expressions "clockwise" and "counterclockwise" appearing in the description of this embodiment shall be understood by referring to FIG. 3). As also shown in FIGS. 3, 4A, and 4B, the drive part 21 holds two rigid pins 23 and 24. The pin 23 is provided so as to function as a support surface for the preload spring 13 to bias the drive part 21 in the first direction about the rotation shaft 17, while the pin 24 is positioned to abut against the fixed stopper 14 to stop the pivotal movement of the drive part 21 when the drive part 21 reaches a predetermined angular position in the rotational movement in the first direction from the load position corresponding to the stationary position. It is understood that, unlike the flexible pin 5 of the striking mechanism in FIGS. 1 and 2, the pin 24 in this embodiment is preferably rigid. As a result, since the drive part does not need to make an abrupt stop without traveling a small-angle deceleration path, the pin 24 may have a specific flexibility. One advantage of the striking mechanism according to the present invention is that the fixed stopper 14 can be arranged so that the striking beak 10 is relatively far from the gong when the hammer is in the stationary position. In fact, since the striking part 22 rotates toward the gong 12 with respect to the drive part 21, there is no need to accurately adjust the position of the striking beak 10 at a relatively short distance with respect to the gong when the hammer is in the stationary position as in a conventional striking device.

[0022] As already mentioned, both the drive unit 21 and the striking unit 22 are arranged so that the former pivots around the geometric axis 17 and the latter around the geometric axis 30. As a result, the hammer 11 can be configured by pivoting parts 21 and 22 relative to each other. The striking mechanism also includes a second return means arranged to apply two opposing return torques to the drive unit and the striking unit, respectively, in order to return the drive unit 21 and the striking unit 22 to a first reciprocal configuration referred to as the stable configuration of the hammer 11. Specifically, the purpose of the second return means is to return the striking unit toward the drive unit, so that the drive unit is stopped in its movement toward the gong, while the striking unit continues its movement toward the gong 12 for striking. Thanks to these second return means, the hammer has a stable resting position where the striking beak is away from the gong. In addition, the purpose of these second return means is to prevent multiple rebounds, and if possible, to prevent a complete rebound. This is well achieved by the present invention with selected second return means. These selected second return means are formed by two magnetic elements 26, 27 held by the drive unit 21 and the striking unit 22 of the hammer 11, respectively. According to the present invention, the second return means consists of two magnetic elements fixedly held by the drive unit 21 and the striking unit 22. The two magnetic elements 26 and 27 are arranged to generate an attractive force between them that returns the drive unit 21 and the striking unit 22 to the stable configuration of the hammer 11. In the illustrated example, the magnetic elements 26 and 27 consist of two cylindrical permanent magnets. The magnetic axes of these magnets coincide with the axis of the cylinder. According to the first embodiment, both permanent magnets 26 and 27 are oriented so that their magnetic axes are parallel to the axis of rotation 30. These two permanent magnets can be said to be axially oriented. In order to obtain magnetic attraction, both magnets have the same polarity. In certain modifications, both magnets are arranged so that their respective centers are equidistant from the axis of rotation 30 on which the striking unit 22 can pivot relative to the drive unit 21.

[0023] The drive unit 21 includes a rear stopper 28 having several functions. The first function is to define a stable configuration of the hammer 11. Advantageously, the striking part abuts against this rear stopper in this stable configuration. This is necessary even in embodiments and modifications where a second return means is provided to apply a specific torque (pretension) to the striking part 22 in a stable configuration where the hammer is stationary in a resting position. The second function of the rear stopper 28 is to synchronously drive the striking part 22 when the drive unit 21 is released after the hammer 11 has been loaded by the striking mechanism. The third function of the rear stopper is to act as a damper when the striking part 22 makes a return motion toward the drive unit 21 after the gong 12 has been struck. This third function is important because it allows for the absorption of residual mechanical energy from the striking part as it rebounds after striking, thereby preventing a full rebound and thus preventing the striking beak 10 from touching the gong again. This is the main objective of the present invention. The rear stopper is preferably rigid and firm to provide effective damping when the striking part 22 moves backward after the gong strike. Furthermore, it is advantageous that the rear stopper has a relatively large contact surface with the striking part. Finally, the rear stopper 28 is advantageously positioned such that the center of gravity of the striking part 22 lies on a circle that is centered on the axis of rotation 30 and passes through the contact surface on the rear stopper.

[0024] The operating principle of the striking mechanism according to the present invention is substantially the same as that described in Patent Document 1, which has already been described. This document is incorporated by reference into this patent application. When the striking mechanism is stationary or in the winding phase, the hammer 11 is in its stable configuration. When the striking mechanism is released at a given moment, the mechanism immediately releases the drive unit 21 of the hammer, allowing the entire hammer to pivot rapidly around the geometric axis 17 toward the gong 12 without changing its configuration. During the pivot, the mechanism is positioned such that the drive unit abuts against the fixed stopper 14, preferably at a relatively large angular distance compared to the safety distance described above, before the striking part 22 reaches the gong 12. The drive unit 21 is stopped by the fixed stopper 14 via a pin 24. However, the articulation between the drive unit 21 and the striking part 22 allows the striking part to continue moving independently and eventually strike the gong 12.

[0025] The pivoting of the striking part 22 around the hinge, resisting the return torque exerted by the permanent magnets 26 and 27, results in a temporary change in the configuration of the hammer 11. Subsequently, after the striking part strikes the gong 12, the gong returns some of the energy it received to the striking part. The magnetic energy associated with the return force exerted by the permanent magnets 26 and 27, i.e., the magnetic energy stored in the magnetic system formed by these two permanent magnets, is added to the energy returned by the gong.

[0026] Referring also to Figures 3, 4A, and 4B, it can be seen that the drive unit 21 and the striking unit 22 largely overlap, and both magnets 26 and 27 are located above and below, respectively, a dividing plane perpendicular to the rotation axis 30. It is also understood that when the two parts of the hammer 11 pivot relative to each other, at least one of the two magnets moves parallel to this dividing plane. The drawings show a striking mechanism in which the hammer is in a stable configuration. In this case, the magnetic axes of the two magnets 26 and 27 are substantially aligned, or, advantageously, slightly offset in the first embodiment so that there is an initial magnetic force torque in the stable configuration of the hammer and thus in the resting position of the hammer. The magnetic axes of the magnets 26 and 27 are oriented in the same direction, i.e., they have the same polarity, and the magnetic force that each magnet exerts on the other is an attractive force. One advantage relating to the illustrated modifications, particularly the first embodiment, is that the magnetic force is oriented parallel to the rotation axis 30. Under such conditions, the magnetic force has the effect of pressing the upper surface of the striking unit 22 against the lower surface of the drive unit 21. It is understandable that such a design is advantageous in stopping the pivoting of the striking part relative to the drive, when the hammer is initially in its stable configuration and then contributes to damping the striking part during the partial rebound after the gong strike. Therefore, the aforementioned initial magnetic force torque is not essential for the striking part to stabilize in the stable configuration of the hammer, especially when the hammer is in a stationary position.

[0027] Returning to the graph in Figure 6, which has already been described, curve 1 is understood to show the change in return torque exerted by the second return means (i.e., exerted by the two permanent magnets 26 and 27, which are axially oriented according to the angle α at which the striking part 22 pivots relative to the drive part 21) in a situation where the drive part of the hammer 11 remains stationary relative to the fixed stopper 14 after striking it, while the striking part 22 continues its rotational motion (forward motion) in the first direction by rotating around the rotation axis 17. It is possible, and even highly probable, for the striking part to continue its rotational motion toward the gong while the drive part strikes the fixed stopper 14. As already described, in the specific modifications described, the return torque generated by the magnets 26 and 27 has a non-zero value due to the slight angular delay expected between the respective magnetic axes of the two magnets when the hammer is in its stable configuration and, in particular, when it is stationary. As the angle α between the two parts 21 and 22 of the hammer deviates from the stable configuration, the return torque increases rapidly and is maintained at a relatively high value over the relatively long angular distance of the angular path in which the striking part 22 moves alone, while the permanent magnets 26 and 27 remain partially overlapping. Finally, in the final section of the angular path of the striking part between the stationary position and the striking position, as soon as the majority of the two magnets separate in the projection onto a plane perpendicular to the axis of rotation 30, the return torque decreases quite rapidly. In this modification of curve 1 in Figure 6, the magnets are configured such that the strength of the return torque reaches its maximum when the two parts 21 and 22 of the hammer rotate relative to each other, and then decreases relatively quickly before the striking beak 10 touches the gong 12. According to the magnetic system of the present invention, moving the striking beak away from the gong in the stationary position of the hammer has only a slight effect on the energy efficiency of the striking device, because the magnetic force between the two magnetic elements decreases to weak or negligible in at least the final section of the angular path of the striking part between the stationary position and the striking position.

[0028] The drive unit 21 of the hammer 11 of the striking mechanism shown in Figures 3, 4A, and 4B holds a single permanent magnet 26. Alternatively, the drive unit may include, for example, an upper part that holds a first magnet and a lower part that holds a second magnet of the same polarity. The first and second magnets are mounted on the drive unit such that their magnetic axes are aligned with each other, in other words. In this alternative embodiment of the first embodiment (not shown), the striking part is positioned to freely mesh between the lower and upper parts of the drive unit. As a result, the magnet held by the striking part is inserted between the upper and lower parts of the drive unit in the stable configuration. As the striking part pivots relative to the drive unit around a rotation axis (defined by a hinge between the two parts), the magnet in the striking part moves between the upper and lower parts in a plane perpendicular to the rotation axis. When the hammer is in its stable configuration, the magnetic axes of the magnet in the striking part and the magnetic axes of the two magnets in the drive unit are substantially aligned. In the first modification, all three magnetic axes are polarized in the same direction. In this first modification, the attractive force exerted by the first magnet in the drive unit on the magnet in the striking unit balances the attractive force exerted by the second magnet in the striking unit. This means that at least a large portion of the frictional force between the drive unit and the striking unit is lost. This can also be advantageous in that it limits the energy lost by the striking unit before it strikes the gong 12 from its resting position. In the second modification, the polarity of the permanent magnet held by the striking unit is reversed with respect to the two permanent magnets held by the drive unit. In this case, the hammer's stabilization configuration has the magnet in the striking unit located upstream of the magnet in the drive unit. The striking unit abuts against a rear stopper that defines the stabilization configuration. The magnetic system is configured such that the kinetic energy from the striking unit is sufficient to easily overcome the peak of the magnetic potential generated by the magnetic repulsion acting when the magnets are aligned in both rotational directions. The magnetic system returns the striking unit to the stabilization position over the initial portion of its angular path relative to the drive unit between the resting position and the striking position.Furthermore, the permanent magnet held by the striking part, or the permanent magnet held by the driving part, can each be replaced in another modified example by a chip made of a diamagnetic material, and by two chips made of such diamagnetic material.

[0029] It should be understood that, according to another modification of this embodiment, the second return means may include only one permanent magnet oriented parallel to the rotation axis 30. In this case, the other magnetic element may be, for example, a tip made of a soft magnetic material having high permeability. In this case, the behavior of the return torque exerted by the second return means, depending on the angle between the striking part 22 and the drive part 21, is qualitatively similar to curve 1 in Figure 6.

[0030] Attached Figures 5 and 5A illustrate a second embodiment of the striking mechanism according to the present invention. The striking mechanism shown has many features in common with the first embodiment. Therefore, not all features of the second embodiment will be described in detail again. It should also be noted that in Figure 5, elements similar to those already described in relation to Figures 3, 4A, and 4B are given the same reference numerals plus 50.

[0031] Referring here to Figures 5 and 5A, it can be seen that the illustrated striking mechanism includes a resonator comprising a hammer 61 and a gong 62, a first return means comprising a preload spring 63, and a fixed stopper 64. The hammer 61 includes a first drive unit 71 and a second striking unit 72. Parts 71 and 72 are assembled by pivot connections so that they can rotate relative to each other about a rotation axis 67. It can be seen that in this example, parts 71 and 72 largely overlap, and both are arranged so that they can rotate independently of each other over at least a certain angular distance about a rotation axis 67, which remains fixed to the support. This is the first major difference from the modification shown in the first embodiment, and this first difference relates to an alternative example in the assembly of the two parts 71 and 72. Therefore, the rotation axis 67 functions, on the one hand, as a fixed rotation axis that allows the drive unit 71 to pivot with the striking unit 72 relative to the fixed support when the hammer is wound up and when the strike is released, and on the other hand, as described above, as a rotation axis that allows the striking unit to pivot relative to the drive unit to strike the gong. The material axis in question is not explicitly shown in Figure 5, but its position is indicated by the geometric axis 67.

[0032] As shown in Figure 5, the drive unit 71 is parallel to the rotation axis 67 and holds two pins 73 and 74 fixed to the side of the drive unit 71 facing the striking unit 72. The pins 73 and 74 are relatively long and extend beyond the striking unit 72. As can also be seen, the striking unit 72 has an elongated hole (not reference numeral) through which the pins 73 pass, and this elongated hole allows for the relative rotational motion foreseen between parts 71 and 72. It is understood that the elongated hole is large enough to allow the pins 73 to move freely in the tangential direction when the striking unit 72 pivots relative to the drive unit 71. As also shown in Figure 5, one end of the preload spring 63 abuts against the pins 73 and the other end is fixed to the support. The preload spring 63 thus functions as a first return means positioned to permanently bias the drive unit 71 in a first direction / forward direction around the rotation axis 67 (the terms "clockwise" and "counterclockwise" appearing in this embodiment should be understood by referring to Figure 5). The pin 74 is positioned so as to abut against the fixed stopper 64 to stop the pivoting of the drive unit 71 when the drive unit 71 reaches a predetermined angular position relative to the support corresponding to the stationary position of part 71.

[0033] As already mentioned, the hammer 61 can be reconfigured by pivoting parts 71 and 72 relative to each other. The striking mechanism also includes a second return means, which is arranged to apply a return torque to the striking part 72 relative to the drive part 71, in order to return the drive part and the striking part to a first reciprocal configuration referred to as the stable configuration of the hammer 61.

[0034] According to the present invention, the second return means consists of two magnetic elements held by the drive unit 71 and the striking unit 72 of the hammer 61, respectively. The two magnetic elements 76 and 77 are arranged to generate an attractive force between them that returns the drive unit 71 and the striking unit 72 to the stable configuration of the hammer 61. In the illustrated example, the magnetic elements consist of two rectangular permanent magnets 76 and 77. The magnetic axes of each of these permanent magnets are substantially aligned in the stable configuration of the hammer 61, and consequently in the resting position of the hammer. In the second embodiment, the magnetic axes of the two magnets 76 and 77 are located in the same plane perpendicular to the axis of rotation 67. This specifically means that the centers of the two magnets 76 and 77 are contained within the said plane, and furthermore, it is understood that the magnets move relative to each other in the same plane when the hammer 61 changes configuration. This is the second main difference between the first and second embodiments, and this second difference is a major difference as it relates to the magnetic system according to the present invention of the described striking device. Each of the two permanent magnets is rigidly fixed to the portion of the hammer 61 that holds it, and the two magnets 76 and 77 are positioned such that their respective centers are equidistant from the axis of rotation 67 from which the drive unit 71 and the striking unit 72 can pivot relative to the support and to each other (in a particular case). Under such conditions, as shown in Figures 5 and 5A, it is understood that the magnetic axes of the two permanent magnets are substantially aligned when the hammer 61 is in its stable configuration. Both permanent magnets are also polarized in the same direction, and therefore the force that each magnet exerts on the other is a magnetic attraction.

[0035] In the illustrated modified example, the drive unit 71 also includes a rear stopper 78 that performs the same function as in the first embodiment. In addition, the rear stopper 78 also allows the two magnets 71, 72 in the magnetic system forming the second return means to not collide with each other during the return / reverse movement of the striker after impact.

[0036] Now, returning to the graph in Figure 6 that was already described, it is understood that curve 2 corresponds to curve 1, but is related to the striking mechanism according to the second embodiment. As can be seen, the return torque generated by magnets 76, 77 reaches its maximum value when the hammer is in its stable configuration / resting position, and this maximum value is relatively high. Unlike curve 1, curve 2 decreases asymptotically and rapidly from the stable configuration towards zero as the striking part moves away from the drive part.

[0037] As already mentioned, the drive unit 71 and the striking unit 72 include a rear stopper 78 positioned to engage with the drive unit 71 to prevent the striking unit 72 from pivoting clockwise / in the first direction relative to the drive unit 71 beyond the stable configuration of the hammer 61. In the second embodiment, the rear stopper 28 is essential due to the fact that the return torque is significant in the stable configuration. A simple solution would be to use two permanent magnets as stoppers. However, the use of the rear stopper 78 shown in Figures 5 and 5A makes it possible to ensure a minimum distance between the magnets 76 and 77, thereby preventing the initial attractive force (and thus energy consumption) from becoming too high, and also protects the permanent magnets from the impact of the striking unit on the drive unit during the return / reverse movement of the striking unit after the gong 62 has been struck.

[0038] It is understood that, according to a modification of the second embodiment, the second return means may include only one magnet oriented in a plane perpendicular to the rotation axis 67. In this case, the other magnetic element may be made of a soft magnetic material having high permeability. The behavior of the return torque exerted by the second return means, depending on the angle α between the striking part 72 and the drive part 21, is qualitatively similar to curve 2 in Figure 6.

[0039] It will also be understood that various modifications and / or improvements will be made to the embodiments described herein without departing from the scope of the invention as defined by the appended claims. [Explanation of Symbols]

[0040] 4 Hammers 5. Gong 6. Preload spring 7. Fixing stopper 8 Flexible pins 9 Fixed axis 10 Beak 11 Hammers 12 Resonator / Gong 13 Preload spring 14. Fixing stopper 17 Fixed Rotating Axis 21 Drive unit 22 Hitting Department 23, 24 pins 26, 27 Permanent magnets 28 Rear stopper 61 Hammer 62 Resonator / Gong 63 Preload spring 64 Fixed stopper 67 Fixed Rotating Shaft 71 Drive unit 72 Hitting Department 73, 74 pins 76, 77 Permanent magnets 78 Rear stopper

Claims

1. A striking mechanism for a clock, comprising a support, a resonator (12; 62), a hammer (11; 61), a stopper (14; 64) fixed to the support, a first return means (13; 63), and a second return means (26, 27; 76, 77), The hammer includes a first part (21; 71) referred to as a drive unit and a second part (22; 72) referred to as a striking unit, which is arranged to strike the resonant body. The drive unit is mounted on the support so as to pivot around a first rotation axis (17; 67) between a first position referred to as a stationary position in contact with the fixed stopper and a second position referred to as a winding position away from the fixed stopper. The first return means (13; 63) is arranged to permanently return the drive unit to the fixed stopper in a first direction, and to rotate the drive unit in the first direction from the winding position after the impact on the resonator is released. The drive unit and the striking unit are assembled by a pivot connection so that the striking unit can pivot relative to the drive unit around a second rotation axis (30; 67). The second return means (26, 27; 76, 77) is arranged to exert a return torque between the drive unit and the striking unit so as to return the drive unit and the striking unit to the first configuration referred to as the stable configuration of the hammer (11; 61), The striking mechanism is arranged such that when the hammer (11; 61) is in the stable configuration and the drive unit (21; 71) is in the stationary position in contact with the fixed stopper (14; 64), the striking unit (22; 72) is separated from the resonator (12; 62). The striking mechanism is such that when the hammer is in the stabilizing configuration and the drive unit (21; 71) strikes the fixed stopper (14; 64) during rotation in the first direction, the kinetic energy of the striking part (22; 72) drives the striking part toward the resonator (12; 62) against the second return means (26, 27; 76, 77) across the angular path of the striking part relative to the drive unit, and thereafter the hammer is positioned to temporarily move away from the stabilizing configuration. A striking mechanism characterized in that the second return means includes two magnetic elements (26, 27; 76, 77) fixedly held by the drive unit and the striking unit, respectively, the two magnetic elements being arranged to generate a magnetic force between them that returns the striking unit and the drive unit to the stable configuration of the hammer, at least over the initial portion of the angular path.

2. The striking mechanism according to claim 1, characterized in that at least one of the two magnetic elements (26, 27; 76, 77) is a permanent magnet.

3. The striking mechanism according to claim 2, characterized in that the magnetic axis of at least one of the magnets is parallel to the second rotation axis (30).

4. The striking mechanism according to claim 2, characterized in that the magnetic axis of at least one of the magnets lies in a plane perpendicular to the second rotation axis (67).

5. The striking mechanism according to claims 1 to 4, characterized in that each of the two magnetic elements (26, 27; 76, 77) is a pair of permanent magnets arranged to magnetically attract each other.

6. The striking mechanism according to claim 5, characterized in that each of the two permanent magnets (26, 27; 76, 77) is rigidly fixed to the portion of the hammer (11; 61) that holds it, and the magnetic axes of each of the two permanent magnets substantially coincide when the hammer is in the stable configuration.

7. The striking mechanism according to claim 5, characterized in that the centers of the two permanent magnets are always located at the same distance from the second axis of rotation.

8. The striking mechanism according to any one of claims 1 to 4, characterized in that the second rotation axis (30) is parallel to the first rotation axis (17) and is positioned at a distance from the first rotation axis.

9. The striking mechanism according to any one of claims 1 to 4, characterized in that the first axis of rotation (67) and the second axis of rotation (67) coincide.

10. The striking mechanism according to any one of claims 1 to 4, characterized in that the drive unit (21; 71) includes a rear stopper (28; 78) that restricts the rotation of the striking unit (22; 72) relative to the drive unit (21; 71) in a direction opposite to the first direction.

11. The striking mechanism according to claim 10, characterized in that the rear stopper (28; 78) forms a damper for the striking part (22; 72) when the striking part returns toward the drive part after the resonant body has been struck.

12. The striking mechanism according to claim 11, characterized in that the rear stopper (28; 78) forms a means for the drive unit (21; 71) to drive the striking unit (22; 72) when the drive unit is rotated from the winding position by the first return means (13; 63) after the striking to the resonator is released.

13. The striking mechanism according to claim 10, characterized in that when the hammer (11; 61) is in the stable configuration, the striking portion (22; 72) contacts the rear stopper (28; 78).

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