EP2960725A1 - Oscillating system for a clock movement with anchor escapement - Google Patents

Abstract

The oscillating system comprises a mechanical resonator comprising a flexible bar (111a) held at one end and arranged to oscillate in a plane around an equilibrium position. The other end of the bar carries a rigid cap (114) which itself carries a hinge (123, 125) arranged to mechanically connect the bar to an anchor (117). When the bar is in the equilibrium position, the articulation is substantially aligned between the pivot (119) and a point of the bar (111 a) situated at a determined distance from the free end thereof, the determined distance being equal to the quotient of the value of the arrow at a given instant, when the bar is not in the equilibrium position, to the value at the same time of the derivative of the deformation of the bar evaluated at the distal end of the bar. bar.

Description

FIELD OF THE INVENTION

The present invention relates to an oscillating system for watch movement with anchor escapement, the oscillating system comprising a mechanical resonator comprising at least one flexible bar held by one end, said proximal end, and arranged to oscillate in a plane around a position of balance, the anchor being arranged to pivot about an axis perpendicular to the plane in which the flexible bar is arranged to oscillate, and the other end of the flexible bar, said distal end, carrying first connecting means arranged for s articulate with second joining means integral with the anchor, so that the anchor pivots alternately in concert with the oscillations of the bar.

PRIOR ART

In the usual mechanical clockwork movements, the synchronous movement of the movement is ensured by a regulating device constituted by a pendulum-balance and escapement assembly. This device, although currently perfectly developed, requires a very delicate adjustment and its accuracy is limited because of its very low oscillation frequency.

The patent document CH 442'153 proposes to realize improved regulator devices which comprise, on the one hand, a mechanical oscillator-regulator, for example a tuning fork mounted on a base, and secondly, an elastic member whose one end is fixed on one base, while the other end has a lift for cooperating with the toothing of the escape wheel of a movement of watchmaking whose speed is regulated by the oscillator-regulator. The energy transferred by the escape wheel to the lifting of the elastic member during successive contacts is transmitted via an elastic coupling to the mechanical oscillator-regulator and maintains the oscillation. This type of connection does not, however, ensure a smooth movement because the condition of agreement or resonance between the two elements (elastic member and oscillator), defining the normal operation of the regulator, can not be maintained especially under the effect of shocks or changes of position which affect their elastic coupling.

The patent document EP 2 574 994 describes an oscillating system for free escapement clock movement as defined in the introduction. According to this prior document, the anchor has a fork having two teeth, and the distal end of the flexible bar carries two pegs spaced from each other and arranged to oscillate transversely to the axis of the bar and to cooperate alternately and respectively with the two teeth of the fork so as to rotate the anchor. The implementation of this known oscillating system presents certain difficulties. Indeed, to allow the mechanical exhaust to work well, it is necessary that the flexible bar can oscillate with sufficient energy. However, a high oscillation energy implies oscillations of relatively large amplitude and therefore including a relatively high oscillation speed at the ankles.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to overcome the disadvantages of the prior art just mentioned. The invention achieves this goal by providing an oscillating system for an escape clock movement. anchor, which conforms to the definition given in the introduction. This oscillating system is further characterized in that the flexible bar carries a rigid cap attached to the distal end, the first connecting means being fixed on the rigid cap at a predetermined location whose position is such that, when the bar is in the equilibrium position, a first segment connecting the determined location to the pivot axis of the anchor and a second segment connecting the determined location to a reference point form between them an angle α of between 150 ° and 180 °; where said reference point is the center of inertia of a straight section of the bar whose position is determined so that the length of the portion of the bar between the reference point and the distal end is equal to the quotient the value of the arrow at a given moment, when the bar is not in the equilibrium position, on the value at the same time of the derivative of the deformation of the bar evaluated at the distal end of the bar.

In accordance with what will be explained in more detail below, we can assimilate the oscillations of the flexible bar cap to a reciprocating around a point where the velocity vector of the cap remains substantially zero. We will call this fixed point the "virtual center" of rotation of the cap. According to the invention, when the flexible bar is in its equilibrium position, the virtual center of rotation of the cap is superimposed on a point of the bar called the reference point. The reference point of the bar is itself defined according to the invention as the point of the bar for which the length of the portion of the bar between the reference point and the distal end is equal to the quotient of the value of the arrow at a given time, when the bar is not in the equilibrium position, on the value at the same time of the derivative of the deformation of the bar evaluated at the distal end of the bar. It should be noted that the invention is not limited to an oscillating system in which the flexible bar has a particular shape. This is the reason for the distance between the distal end and the reference point of the bar is expressed in the very general terms above.

The oscillation movement of the rigid cap driven by the flexible bar thus corresponds to an alternating rotational movement around the virtual center. Under these conditions, the amplitude and speed of the oscillations of a given point of the cap are proportional to a distance separating this given point from the virtual center. According to an advantageous embodiment of the invention, the distance separating the virtual center of the joint is less than the distance separating the virtual center from the distal end of the flexible bar. It will be understood that under these conditions, the speed of the oscillations at the articulation between the cap and the anchor is advantageously reduced.

The short theoretical parenthesis which follows is intended to contribute to a good understanding of the general scope of the invention as defined by appended claim 1. First, the oscillating system of the invention comprises a mechanical resonator which comprises at least one flexible bar held by one end. The second end of the bar is free, and the bar is arranged to oscillate in a plane around an equilibrium position. The figure 4 is a schematic diagram illustrating the elastic deformation of a flexible bar recessed.

In the figure, the flexible bar of length L is represented by a single line referenced 3. Line 3 is the average fiber. It is an imaginary curve passing through the centers of inertia G of all the straight (transversal) sections of the bar (we can specify that the average fiber corresponds to the neutral fiber in the case where the straight sections have a profile symmetrical). Moreover, the dashed line referenced 5 on the figure 4 is the undeformed average line. It will therefore be understood that, when the bar is in its equilibrium position, the curve 3 is superimposed on the average line 5. The flexural deformations of the bar can be quantified by a function called "the deformed" υ (x). The Deformed υ (x) is defined as the displacement of the center of inertia G of a cross-section located at a distance "x" from the point of embedding of the bar (o ≤ x ≤ L). This displacement is measured perpendicularly to the average line 5. Moreover, when the deformations of the bar are weak, the deformed υ (x) is proportional to the force (referenced F) which causes the bending. The value of the deformation at the free end of the bar is called "arrow" (denoted f). Under the same conditions of small deformations, it can also be considered that the straight sections of the bar remain straight and perpendicular to the neutral fiber during the deformation.

According to the invention, a rigid cap is attached to the free end of the bar. As a first approximation, when the bar is deformed, the cap moves parallel to the plane of oscillation of the bar integrally with its free end. In such a context, the classical kinematics teaches us that at each instant when the bar oscillates, it is possible to identify an instantaneous center of rotation (CIR) around which the rigid cap is rotating without translation. The CIR is the point of the headdress whose speed is zero. The theory also teaches us that the CIR is at the intersection between the perpendiculars to the velocity vectors of each point of the cap. Thus, since the speed vector of the center of inertia G _{x = L} of the terminal cross section is oriented perpendicular to the neutral fiber 3, the CIR is necessarily on the right which is tangent to the bar at its end. This line is given by the following formula: $$v\left(\mathrm{The};;t\right)+\frac{\mathit{dv}\left(\mathrm{The};;t\right)}{\mathit{dx}}\left(x-\mathrm{The}\right)=\mathrm{there}$$

It has been hypothesised that the straight sections of the bar are always oriented perpendicular to the neutral fiber. Under these conditions, it can be shown that the points of the cap whose trajectories intersect at a given instant the line corresponding to the rest position of the axis of the bar are, at this given moment, all animated with directed speeds. perpendicular to this line. In other words, at a given instant, the line corresponding to the rest position of the axis of the bar is perpendicular to the velocity vectors of all the points whose trajectories intersect this line at this given instant. The CIR is therefore on the line corresponding to the rest position of the axis of the bar. This axis corresponds to the line whose equation is as follows: $$\mathrm{there}=0$$

ou de manière équivalente (en posant λ = L - x) : $$\lambda \cdot \frac{\mathit{dv}\left(x=L\right)}{\mathit{dx}}=v\left(x=L\right)$$

où λ est la distance entre l'extrémité libre et le centre instantané de rotation.We deduce from (i) and (ii) that for the instantaneous center of rotation: $$\mathrm{\upsilon }\left(\mathrm{The}\right)+\frac{\mathit{dv}\left(\mathrm{The}\right)}{\mathit{dx}}\left(x-\mathrm{The}\right)=0$$

or in an equivalent way (by posing λ = L - x): $$\lambda \cdot \frac{\mathit{dv}\left(x=\mathrm{The}\right)}{\mathit{dx}}=v\left(x=\mathrm{The}\right)$$

where λ is the distance between the free end and the instantaneous center of rotation.

$$\frac{\mathit{dv}\left(x,t\right)}{\mathit{dx}}=F\left(t\right)\cdot \frac{d\bar{v}\left(x\right)}{\mathit{dx}}$$

où v (x) dépend de la forme du barreau et du matériau dont il est fait.It will be further noted that the distance at which the CIR is from the free end does not depend on the amplitude of the deformation. Indeed, it has been said above that the amplitude of the deformation of the bar depends only on the intensity of the force which causes the flexion. Under these conditions, we can separate the variables t and x and express the deformed and its derivative respectively by the following two formulas: $$v\left(x,t\right)=F\left(t\right)\cdot \tilde{v}\left(x\right)$$

$$\frac{\mathit{dv}\left(x,t\right)}{\mathit{dx}}=F\left(t\right)\cdot \frac{d\tilde{v}\left(x\right)}{\mathit{dx}}$$

or v ( x ) depends on the shape of the bar and the material of which it is made.

Thus equation (iv) can be rewritten: $$\lambda \cdot F\left(t\right)\cdot \frac{d\tilde{v}\left(\mathrm{The}\right)}{\mathit{dx}}=F\left(t\right)\cdot \tilde{v}\left(\mathrm{The}\right)$$

It will therefore be understood that the force F ( t ) can be eliminated by simplification and that the determined distance at which the CIR is from the end of the bar is therefore constant (within the validity limit of the hypotheses related to small oscillations). The CIR is therefore immobile in first approximation when the bar is deformed in flexion. Since the instantaneous center of rotation is not strictly speaking "instantaneous", we preferred to use the alternative expression "virtual center" to designate it.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 est une vue schématique en plan d'un système oscillant selon un premier mode de réalisation de l'invention ;
• la figure 2 est une vue schématique en plan d'un système oscillant selon un deuxième mode de réalisation de l'invention ;
• la figure 3 est une vue schématique en plan d'un système oscillant selon un troisième mode de réalisation de l'invention ;
• la figure 4 est un schéma de principe illustrant la déformation d'un barreau flexible encastré dont l'extrémité libre est soumise à une force ;
• la figure 5A est une représentation en plan plus détaillée d'un système oscillant selon un quatrième mode de réalisation de l'invention ;
• la figure 5B est une vue partielle agrandie montrant plus particulièrement les premiers et les seconds moyens de jonction du système oscillant de la figure 5A ;
• la figure 6 est une vue schématique en plan d'un système oscillant selon un cinquième mode de réalisation de l'invention ;
• la figure 7 est une représentation détaillée en plan d'une variante alternative du système oscillant illustré dans la figure 5A.

Other features and advantages of the present invention will appear on reading the following description, given solely by way of non-limiting example, and with reference to the appended drawings in which:

• the figure 1 is a schematic plan view of an oscillating system according to a first embodiment of the invention;
• the figure 2 is a schematic plan view of an oscillating system according to a second embodiment of the invention;
• the figure 3 is a schematic plan view of an oscillating system according to a third embodiment of the invention;
• the figure 4 is a schematic diagram illustrating the deformation of a recessed flexible bar whose free end is subjected to a force;
• the Figure 5A is a more detailed plan representation of an oscillating system according to a fourth embodiment of the invention;
• the Figure 5B is an enlarged partial view showing more particularly the first and second connecting means of the oscillating system of the Figure 5A ;
• the figure 6 is a schematic plan view of an oscillating system according to a fifth embodiment of the invention;
• the figure 7 is a detailed plan representation of an alternative variant of the oscillating system illustrated in FIG. Figure 5A .

DETAILED DESCRIPTION OF DIFFERENT EMBODIMENTS

The figure 1 attached is a schematic plan view of an oscillating system according to a first embodiment of the invention. It is possible to see in the figure a flexible bar 11 secured by one of its ends, called the proximal end, of a fixed support 13. The other end of the bar, called the distal end, bears a rigid cap 15 which is large in size. comparison with the flexible bar. In the example shown, the bar 11, the support 13 and the cap 15 are made of material and extend in the same plane. These three elements are preferably made by micromachining of a crystalline silicon wafer. It will be understood, however, that these elements do not necessarily come from material according to the invention, and that in general, these elements could be made of any other suitable material known to those skilled in the art. For example quartz, glass, ceramics or amorphous metals. In addition, the skilled person could use a method other than micromachining.

Referring again to the figure 1 it may be noted that the cap 15 has a shape that is almost symmetrical with respect to the axis of the undeformed bar. In addition, the cap is almost double the length of the bar 11. It can be seen in the cap a head portion 15a which extends in the extension of the bar and two side portions 15b and 15c which extend back symmetrically. on either side of the axis of the bar. The shape of the cap 15 is preferably chosen so that its center of inertia is in the immediate vicinity of the distal end of the bar 11.

Referring again to the figure 1 , we can see an escape wheel 18 which cooperates with an anchor 17 mounted on a pivot 19. In known manner, the anchor 17 is provided with a rod 21 which ends with a fork 23. The side part 15c of the cap wears a peg 25 arranged to cooperate with the fork 23. It will be understood that, in the present example, the peg and the fork constitute the first and the second joining means according to the invention. It will be understood that the pin and the fork are arranged to cooperate to form an articulation connecting the cap 15 to the anchor 17. In the illustrated embodiment, it is seen that the pivot 19 of the anchor and the articulation between the ankle and the fork are on the same line which is perpendicular to the bar 11 in its rest position. The figure 1 is a plan view. It will thus be understood that in the absence of information concerning the elevation of the elements shown, the anchor 17 and the flexible bar 11 may be located, or together in the plane of oscillation of the bar (the plane of the sheet of the drawing of the figure 1 ), or at different heights. However, even in the second alternative, the articulation is contained in the rod plane which is a plane perpendicular to the plane in which the rod oscillates (perpendicular to the drawing sheet). Whatever the variant of the embodiment of the figure 1 the rod plane is perpendicular to the axis of the bar 11 in the rest position, and the trace of the rod plane on the plane of the sheet is a line perpendicular to the bar.

Referring again to the figure 1 it can be verified that if a straight line is drawn in the drawing which passes through both the pivot 19 and the hinge 23, 25, this line intersects the flexible bar at a point referenced 27 The point of the bar which is referenced 27 in the figures is called the "reference point" of the bar. In accordance with what will be explained in more detail below, when the bar is in its equilibrium position, the reference point 27 coincides with the virtual center around which the cap 15 seems to pivot.

Referring again to the figure 1 we can see a circle referenced c and whose center corresponds to the virtual center. In addition, the circle c passes through the articulation between the ankle 25 and the fork 23. The radius of the circle c is therefore equal to the distance separating the virtual center from the articulation. The figure 1 clearly shows that this distance is less than the distance separating the virtual center from the distal end of the flexible bar 11. In fact, in the example shown, the radius c is even considerably less than half the distance between the virtual center and the distal end of the bar. Under these conditions, the amplitude and speed of the oscillations of the joint are less than one-third of the amplitude and the speed of the oscillations of the distal end of the bar 11. It will therefore be understood that the oscillating system illustrated in FIG. figure 1 it makes it possible to reduce the oscillation speed of an anchor secured to a resonant bar sufficiently to make these oscillations compatible with the proper operation of an anchor escapement.

On comprendra que cette distance dépend naturellement de la forme du barreau.According to the invention, the distance between the distal end and the reference point 27 of the bar 11 is equal to the quotient of the value of the arrow at a given instant (υ ( x = L, t )), when the bar is not in the equilibrium position, on the value at the same time of the derivative of the deformed bar evaluated at the distal end of the bar $\left(\frac{\mathit{dv}\left(x=\mathrm{The}\right)}{\mathit{dx}}\right)\mathrm{.}$

It will be understood that this distance naturally depends on the shape of the bar.

et que la dérivée de la déformée est égale à $\frac{\mathit{dv}\left(x\right)}{\mathit{dx}}=\frac{6\mathit{Fx}\left(2L-x\right)}{\mathit{Eh}{d}^3};$

où F est la force, d est le côté de la section carrée et E est le module de Young.In the case of a constant square section bar, the forms indicate that the deformed is equal to $\mathrm{\upsilon }\left(x\right)=\frac{2F{x}^2\left(3\mathrm{The}-x\right)}{\mathit{<figure-callout\; id="3"\; label="Well\; \; d"\; filenames="imgf0002.png"\; state="\{\{state\}\}">Well\; </figure-callout>}{d}^{}{}^3},$

and that the derivative of the deformed is equal to $\frac{\mathit{dv}\left(x\right)}{\mathit{dx}}=\frac{6\mathit{Fx}\left(2\mathrm{The}-x\right)}{\mathit{<figure-callout\; id="3"\; label="Well\; \; d"\; filenames="imgf0002.png"\; state="\{\{state\}\}">Well\; </figure-callout>}{d}^{}{}^3};$

where F is the force, d is the side of the square section and E is the Young's modulus.

Applying the formula of equation (iv) given above to this particular case, it is found that the distance between the distal end and the reference point 27 is equal to λ = ^{2 L} / ₃ . This is what the Figures 1, 2 , 3 , 5 and 6 (to some inaccuracies ready).

et que la dérivée est égale à : $$\frac{\mathit{dv}\left(z\right)}{\mathit{dz}}=\frac{12\mathit{PL}}{{\mathit{Eb}}_L{t}^3}Z+\frac{12{\mathit{PL}}^2}{{\mathit{Eb}}_L{t}^3};$$

où z = L - x (et donc z = 0 à l'extrémité distale du barreau).As an alternative example, one can also cite the case not shown in the figures of a tapered bar (whose linear quadratic moment decreases linearly from the embedding point). In this case, the formulas indicate that the deformed is equal to: $$\mathrm{\upsilon }\left(\mathrm{z}\right)=-\frac{12\mathit{PL}}{{\mathit{Eb}}_{\mathrm{The}}{t}^3}\left(\frac{z^2}{2}\right)+\frac{12{\mathit{PL}}^2}{{\mathit{Eb}}_{\mathrm{<figure-callout\; id="3"\; label="The\; \; t"\; filenames="imgf0002.png"\; state="\{\{state\}\}">The\; </figure-callout>}}{t}^{}{}^3}Z+\frac{6{\mathit{PL}}^6}{{\mathit{Eb}}_{\mathrm{<figure-callout\; id="3"\; label="The\; \; t"\; filenames="imgf0002.png"\; state="\{\{state\}\}">The\; </figure-callout>}}{t}^{}{}^3},$$

and that the derivative is equal to: $$\frac{\mathit{dv}\left(z\right)}{\mathit{dz}}=\frac{12\mathit{PL}}{{\mathit{Eb}}_{\mathrm{<figure-callout\; id="3"\; label="The\; \; t"\; filenames="imgf0002.png"\; state="\{\{state\}\}">The\; </figure-callout>}}{t}^{}{}^3}Z+\frac{12{\mathit{PL}}^2}{{\mathit{Eb}}_{\mathrm{<figure-callout\; id="3"\; label="The\; \; t"\; filenames="imgf0002.png"\; state="\{\{state\}\}">The\; </figure-callout>}}{t}^{}{}^3};$$

where z = L - x (and thus z = 0 at the distal end of the bar).

Applying again the formula of equation (iv) given above, we find that, in this second case, the distance between the distal end and the reference point is equal to λ = ^L / ₂ .

On the other hand, whatever the shape of a flexible bar, the skilled person is able to calculate the value of the arrow and the derivative of the deformation of the bar evaluated at the distal end of the bar, for example , by a finite difference calculus.

The figure 2 is a schematic plan view of an oscillating system according to a second embodiment of the invention. The elements that are common to the oscillating systems according to the first and second embodiments are designated by the same reference numerals on the figure 2 and on the figure 1 . Comparing the Figures 1 and 2 , it may be noted in particular that the cap 115 does not have exactly the same shape as the cap 15. It is nevertheless verified that the distance between the virtual center (the reference point 27) and the articulation is the same on the figure 2 that on the figure 1 . However, according to the second embodiment, the rod plane containing the pivot 19 and the joint intersects the axis of the bar 11 at the location of the reference point 27 obliquely (with an angle of about 45 ° in the illustrated example). It will be understood that since the distance between the virtual center and the joint is the same on the figure 2 that on the figure 1 , amplitude and velocity of oscillations of the joint are substantially the same in the oscillating system of the figure 2 than in that of the figure 1 .

The figure 3 is a schematic plan view of an oscillating system according to a third embodiment of the invention. According to this embodiment, the mechanical resonator is constituted by a tuning fork referenced 10. As shown in the figure, the tuning fork comprises two parallel bars 11a and 11b which are connected by one of their ends, called the proximal end, to a bar cross link 12. The connecting bar is itself connected in the middle to a fixed support 13. Each of the two bars carries a cap (referenced 15) which is identical to the cap illustrated in FIG. figure 1 . Referring again to the figure 3 it can be seen that one of the two caps (the one on the right in the illustrated variant) is connected via an ankle 25 and a fork 23 to the anchor 17.

It is known that, in a tuning fork, as a first approximation each bar 11a, 11b can be considered in isolation to determine the resonance frequency. However, a benefit associated with the symmetry of the tuning fork 10 is that it favors some well-defined vibration modes having a high quality factor.

The Figure 5A is a more detailed plan representation of an oscillating system according to a fourth embodiment of the invention. In the illustrated embodiment, as in the previous embodiment, the mechanical resonator is constituted by a tuning fork (referenced 110). The tuning fork 110 comprises two parallel bars 111a and 111b of constant section and which are connected to each other by a connecting bar 112 which extends transversely between the proximal ends of the two bars. The connecting bar 112 is itself connected in the middle to a fixing arm 113. The distal end of the bar 111 has a cap 114, and that of the bar 111 b carries a cap 116. It can be seen in the figure that the caps are large in comparison with the bars of the tuning fork. It is also observed that the whole formed by the tuning fork 110 and the caps 114 and 116 has an axis of symmetry which, in the example shown, coincides with the attachment arm 113. The caps 114 and 116 are designed so that their center of inertia is at immediate proximity of the distal end of the bar (respectively 111a and 111b) to which they are attached. In the example shown, the tuning fork 110, the attachment arm 113 and the caps 114 and 116 are made of material and extend in the same plane. These four elements are preferably made by micromachining a monocrystalline silicon wafer.

Referring again to the Figure 5A we can see an escape wheel 118 with 90 teeth. The escape wheel cooperates with an anchor 117 mounted on a pivot 119. The anchor 117 is provided with a rod 121 which ends with an apple 123. It can still be seen in the figure that the cap 114 (the one on the right ) has a notch 125 arranged to receive the apple 123. The notch and the apple are shown in more detail in the Figure 5B . As can be seen the notch and the apple cooperate to form an articulation connecting the cap 114 to the anchor 117. The articulation between the apple and the notch preferably has a certain clearance. For example, the apple could have a diameter of 200 μm and the width of the notch could be 240 μm. Note further that, according to a variant not shown, the first and second joining means according to the invention could be designed to be coupled magnetically or electrostatically to each other (possibly even without any mechanical contact).

As already mentioned, the bars 111a and 111b of the tuning fork 110 are of constant section. Under these conditions, the distance between the distal end of the bar 111a and the reference point 27 must be equal to λ = ^{2 L} / ₃ .

On the other hand, again referring to the Figure 5A it can be estimated that the distance between the virtual center (or equivalently the reference point 27) and the articulation corresponds approximately to 2/5 of the distance between the virtual center and the distal end of the bar 111 a. Under these conditions, the amplitude and the speed of the oscillations at the joint correspond to about 40% of the amplitude and the speed of the oscillations of the distal end of the bar 111a.

Finally, the escape wheel 118 shown on the figure 5 has 90 teeth, which corresponds to an unusually high number of teeth. A high number of teeth is an advantageous characteristic. Indeed, the tuning fork 110 is designed to oscillate with a frequency considerably higher than that of a balance-spring resonator. For example, if the tuning fork oscillates at the frequency of 90 Hz, it follows that the illustrated escapement wheel advances at the speed of one revolution per second. This speed is already considerably higher than that of the exhaust wheel of a classic watch. If the escape wheel 118 had half the teeth, it would run twice as fast.

The figure 6 annexed is a schematic plan view of an oscillating system according to a fifth embodiment of the invention. This oscillating system is very similar to the first embodiment illustrated by the figure 1 . However, as will be seen in more detail below, although the oscillating system of the figure 6 according to the invention, it can be described as "non-optimal". Indeed, it can be verified that if a straight line is drawn in the drawing which passes through both the pivot 19 and the articulation between the first and the second joining means 23 and 25, this line intersects the bar flexible in a certain distance from the reference point 27. In other words, in the illustrated embodiment, the segment connecting the hinge to the reference point 27 is not exactly in the extension of the segment connecting the pivot 19 to the joint . Since the joint is not located on the segment that connects the pivot 19 to the virtual center, it follows that the segment connecting the articulation to the pivot axis 19 forms an angle with the segment connecting the articulation to the point of rotation. 27. Note however that according to the invention, the angle α between the segment connecting the joint to the pivot axis 19 and the segment connecting the joint to the reference point 27 can not be less than 150 °. The angle α is therefore between 150 and 180 °.

The figure 7 is a detailed plan representation of an alternative variant of the oscillating system illustrated in FIG. Figure 5A . The elements that are common to the oscillating systems according to the two illustrated variants of the fourth embodiment are designated by the same reference numerals on the figure 7 and on the Figure 5A . Comparing the Figures 5A and 7 , it can be noted in particular that the caps 214 and 216 are not identical to the caps 114 and 116. In fact, referring to the figure 7 it is observed that the caps 214 and 216 each have a thickening (respectively referenced 220 and 222) located in the immediate vicinity of the distal end of one of the flexible bars 111a, 111b. An advantage associated with the presence of the thickenings 220 and 222 is that it makes it possible to increase the mass of inertia of the caps 214 and 216 without unduly increasing the moment of inertia of the caps relative to their point of attachment on the distal end. one of the flexible bars. According to a preferred variant, the caps are arranged in the plane in which the flexible bars 111a and 111b are arranged to oscillate, and each of the caps has two thickenings arranged symmetrically on its two main faces on either side of the plane in which the flexible bars 111a and 111b are arranged to oscillate. The thickenings 220, 222 are preferably formed of a denser material than the material of the cap 214, 216 and the bar 111a, 111b. In the illustrated example, these thickenings are in the form of coating layers. However, these thickenings could as well be in the form of inserts for example. It will be further understood that the thickenings could be formed of the same material as the caps.

It will be further understood that various modifications and / or improvements obvious to those skilled in the art can be made to the embodiments which are the subject of the present description without departing from the scope of the present invention defined by the appended claims. For example, the anchor visible on one or the other of the figures could be replaced by a flexible anchor without pivot. Such a flexible anchor comprises one or more anchoring points integral with a fixed support, and further comprises flexible portions which give it mobility relative to said fixed support. As is well known to those skilled in the art, even a flexible anchor is arranged to pivot about an axis (it will be understood that even if it is not precisely the entire structure of the anchor which pivots about an axis, the anchor proper, or in other words, its part intended to cooperate with the escape wheel, necessarily pivots about an axis). This is called a "virtual pivot". It will therefore be understood that according to certain embodiments, the pivot axis according to the invention may correspond to a virtual pivot.

Claims (20)

Oscillating system for an anchor escapement watch movement comprising a mechanical resonator comprising at least one flexible bar (11; 11a; 111a) held by a first end, said proximal end, and arranged to oscillate in a plane around a position equilibrium, said anchor (17; 117) being arranged to pivot about an axis (19; 119) perpendicular to the plane in which the flexible bar is arranged to oscillate, the second end of the bar, said distal end, bearing first junction means (25; 125) arranged to articulate with second connecting means (23; 123) secured to the anchor, so that the anchor pivots alternately in concert with the oscillations of the bar; characterized in that the flexible bar (11; 11a; 111a) carries a rigid cap (15; 114; 115; 214,216) attached to the distal end, the first joining means (25; 125) being attached to the rigid cap at a predetermined location whose position is such that, when the bar is in the equilibrium position, a first segment connecting the determined location to the pivot axis (19; 119) of the anchor and a second segment connecting the determined location to a reference point (27) is between them an angle (α) between 150 ° and 180 °;
where said reference point (27) is the center of inertia of a straight section of the bar whose position is determined so that the length of the portion of the bar between the reference point and the distal end is equal to the quotient of the value of the arrow at a given instant, when the bar is not in the equilibrium position, to the value at the same time of the derivative of the deformation of the bar evaluated at the distal end of the bar ; Oscillating system for an anchor escapement watch movement according to claim 1, wherein a distance separating the reference point (27) from the articulation between the first means of junction (25; 125) and the second joining means (23; 123) is less than the length of the portion of the bar between the reference point (27) and the distal end when the bar is in the position balance. Oscillating system for an anchor escapement watch movement according to claim 1 or 2, wherein the cap and the bar are made of material. Oscillating system for an anchor escapement watch movement according to one of claims 1, 2 or 3, wherein the cap is of planar shape and extends substantially in the plane in which the flexible bar is arranged to oscillate. An oscillating system for an anchor escapement clock movement according to any one of the preceding claims, wherein the bar and the cap are each made of a material selected from the group consisting of silicon, quartz, glass, ceramics and metals amorphous. Oscillating system for an anchor escapement watch movement according to claim 5, wherein the bar and the cap are made of the same material. A pendulum swing system with an anchor escapement according to any one of the preceding claims, wherein the center of inertia of the rigid cap is located at the distal end of the bar. A swing system for an anchor escapement clock movement according to any one of the preceding claims, wherein the cap (214, 216) has at least one thickening (220, 222) located near the distal end of the flexible bar ( 111a, 111b). Oscillating system for an anchor escapement watch movement according to claim 8, wherein the thickening (220, 222) is formed of a first material which is denser than a second material in which the cap (214, 216) is made. An anchor escapement oscillating movement system according to claim 9, wherein the thickening is formed by at least one insert. Oscillating system for an anchor escapement watch movement according to any one of the preceding claims, wherein the articulation between the first and second connecting means (25, 23; 125, 123) and the pivot axis (19 : 119) of the anchor are aligned perpendicular to the bar when the bar is in the equilibrium position. An oscillating system for an anchor escapement clock movement according to any one of claims 1 to 10, wherein the articulation between the first and second connecting means (25, 23; 125, 123) and the pivot axis (19) of the anchor are aligned along an oblique line with respect to the bar when the bar is in the equilibrium position. A swing system for an anchor escapement clock movement according to any of the preceding claims, wherein the cap (15; 114,115; 214; 216) carries the first joining means (25; 125) out of the plane in wherein the flexible bar (11; 11a; 111a) is arranged to oscillate. An oscillating movement system with an anchor escapement according to any one of the preceding claims, wherein the bar (11; 11a; 111a) has a constant section. A swing system for an anchor escapement clock movement according to any of claims 1 to 13, wherein the cross-section of the bar (11; 11a; 111a) tapers towards the distal end. An oscillating system for an anchor escapement clock movement according to any one of the preceding claims, wherein the mechanical resonator comprises a tuning fork (10; 110), the flexible bar (11a; 111a) constituting one of the tuning fork arms. Oscillating system for an anchor escapement watch movement according to any one of the preceding claims, in which the first connecting means comprise an anchor (25) integral with the cap (15), and the second connecting means comprise a fork ( 23) integral with the anchor (17), the pin and the fork being arranged to cooperate. A swing system for an anchor escapement movement according to any one of claims 1 to 16, wherein the first joining means comprises a notch (125) having the cap (114; 214), and the second joining means comprise an apple (123) secured to the anchor (117), the notch and the apple being arranged to cooperate. Clock movement comprising an oscillating system according to one of the preceding claims. Timepiece comprising a watch movement according to claim 19.

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