EP3982206A1 - Timepiece oscillator - Google Patents

Abstract

The horological oscillator according to the invention comprises a balance (2) mounted on a balance shaft (3), a balance plate (16) mounted on the balance shaft (3) and carrying a pin (26), and an escapement rocker (14) comprising a body (14a) mounted on an escapement rocker shaft (15) and a fork (20) at one end of the body (14a). The body (14a) extends over a first level and the fork (20) extends over a second level. The fork (20) is arranged to cooperate with the pin (26) in order to maintain the oscillations of the balance. Pin (26) protrudes from balance plate (16) parallel to balance shaft (3). The pin (26) is directed towards the balance (2).

Description

The present invention relates to a horological oscillator, typically an oscillator of a horological movement, comprising a balance mounted on a balance shaft, a balance plate mounted on the balance shaft and carrying a pin, and an escapement rocker comprising a body mounted on an escapement rocker shaft and a fork at one end of the body. The body extends over a first level and the fork extends over a second level. The fork is arranged to cooperate with the pin in order to maintain the oscillations of the balance. The peg protrudes from the balance plate parallel to the balance shaft.

This type of oscillator is found, in particular, in watch movements with a semi-direct impulse escapement, for example with an escapement as described in the patent EP 2941673 B1 . A semi-direct impulse escapement is an escapement whose escape wheel communicates to the balance plate a direct impulse and an indirect impulse, via an escapement rocker, at each period of oscillation, the direct impulse being communicated during one of the two alternations of the balance and the indirect impulse during the other alternation. The fork of the escapement rocker is on a different level from that of the body of the escapement rocker so as not to collide with the escapement wheel or with a tooth of the balance plate which cooperates with the exhaust during the direct impulse. This construction of the escapement rocker in two levels increases the overall height of the oscillator.

We also know a watch movement, namely the caliber 177 of the Patek Philippe brand, in which the escapement rocker (here a Swiss lever) is folded in four places to define a first level comprising the body of the rocker and a second level including the input and output pallets and the fork. The fork is close to the balance and cooperates with a peg driven into one arm of the pendulum. This construction is compact in height but it requires fixing a peg to the balance, which can have negative consequences such as a deformation of the balance or a lack of precision in the position of the peg.

The present invention aims to remedy the aforementioned drawbacks of the state of the art and to this end proposes a timepiece oscillator according to claim 1, particular embodiments being defined in the dependent claims.

The present invention further proposes a timepiece, for example a watch, comprising such an oscillator.

• la figure 1 est une vue en coupe d'un oscillateur horloger selon l'invention ;
• la figure 2 est une vue de dessus d'un échappement de l'oscillateur horloger selon l'invention ;
• les figures 3 à 12 montrent différents états de l'échappement de l'oscillateur horloger selon l'invention pendant son cycle de fonctionnement ;
• la figure 13 montre, respectivement en trait plein et en trait pointillé, deux positions de repos successives de l'échappement de l'oscillateur horloger selon l'invention ;
• la figure 14 montre en perspective un plateau de balancier de l'oscillateur horloger selon l'invention.

Other characteristics and advantages of the present invention will appear on reading the following detailed description given with reference to the appended drawings in which:

• the figure 1 is a sectional view of a horological oscillator according to the invention;
• the figure 2 is a top view of an escapement of the horological oscillator according to the invention;
• the figures 3 to 12 show different states of the escapement of the clock oscillator according to the invention during its operating cycle;
• the figure 13 shows, respectively in solid line and in dotted line, two successive rest positions of the escapement of the horological oscillator according to the invention;
• the figure 14 shows in perspective a balance plate of the horological oscillator according to the invention.

With reference to figures 1 to 3 , a horological oscillator according to a particular embodiment of the invention, for a horological movement, in particular a watch movement, comprises a resonator 1 and an escapement 10 arranged to sustain the oscillations of the resonator 1.

The resonator 1 comprises a balance 2 mounted on a balance shaft 3 and a spring 4, typically a hairspring, arranged to return the balance 2 to an equilibrium position.

The escapement 10 comprises an escape wheel 12, an escapement rocker 14 and a balance plate 16.

The escape wheel 12 is mounted on an escape wheel axle 13 and is coaxially secured to a pinion 18 which meshes with the second wheel 19 of a going train. The latter tends to rotate the escape wheel 12 in a single direction, which is counterclockwise on the figures 2 to 12 . The escape wheel 12 comprises on its periphery, on the same level and alternately, short teeth 36 and long teeth 38. By the terms "short" and "long" is meant that the distance between the top of the tooth and the escape wheel axis 13 is smaller for the short teeth 36 than for the long teeth 38. The short teeth 36 are identical and regularly distributed. The long teeth 38 are also identical and regularly distributed. However, each short tooth 36 may be closer to one of the two adjacent long teeth 38 between which it is situated than to the other, as can be seen in the drawings.

The escapement rocker 14 is mounted on an escapement rocker shaft 15 and comprises a body 14a through which the shaft 15 passes. A fork 20, a first arm 22 and a second arm 24 protrude from the body 14a. At its distal end, the first arm 22 of the escapement rocker 14 defines a first resting surface 30 of concave shape. Similarly, at its distal end the second arm 24 of the escapement rocker 14 defines a second resting surface 32 of concave shape. These concave surfaces 30, 32 can be curved surfaces or consist of two inclined planes. A side impulse surface 34 adjoins the second resting surface 32 on the second arm 24.

The balance plate 16 is mounted on the balance shaft 3 to rotate coaxially and integrally with the balance 2. The balance plate 16 carries a plate pin 26, an impulse tooth 28 and a self-starting tooth 46.

The escape wheel 12, the escapement rocker 14 and the balance plate 16 can be held on their respective axes 13, 15, 3 elastically, as shown, or in another way, for example by gluing or brazing. The axes 13, 15 of the escapement wheel 12 and of the escapement rocker 14 as well as the axis of the seconds wheel 19 each have one end which pivots in a plate 5 which can be the plate of the watch movement and another end which pivots in an escapement bridge 29. The balance shaft 3 pivots at one end in the plate 5 and at its other end in a balance bridge 6.

The escapement 10 is of the type with one pulse per alternation, more precisely of the semi-direct pulse type. Each alternation (half-period of oscillation) of the balance 2 comprises a rest phase, a release phase and an impulse phase. The figures 3 to 12 show successive states of the escapement 10 during the oscillation period.

In a first state ( picture 3 ), a short tooth 36a bears against the first resting surface 30 of the escapement rocker 14. The concave shape of the first resting surface 30 allows the escapement wheel 12 and the escapement rocker 14 to lock each other. The escapement wheel 12 and the escapement rocker 14 are in an entry rest position. The balance plate 16 rotates freely in a first direction S1, namely clockwise on the picture 3 , under the action of the return spring 4 of the balance 2.

At a given moment, pin 26 of balance plate 16, still rotating in direction S1, engages in fork 20 and comes into contact with inner surface 40a of one 40 of the latter's horns to rotate the escapement rocker 14 and release escapement wheel 12 from first resting surface 30 ( figure 4 ). The escape wheel 12 is partially released, its rotation being braked by a transition surface 44 of the first arm 22 on which the short tooth 36a must slide.

As soon as escapement rocker 14, still under the action of pin 26, has completely freed escapement wheel 12 ( figure 5 ), a long tooth 38a catches the impulse tooth 28 to drive it and thus communicate a direct impulse to the balance plate 16 in the direction S1 ( figure 6 and 7 ).

After this impulse, another long tooth 38b abuts against the second resting surface 32 of the escapement rocker 14 ( figure 8 ). The concave shape of the second resting surface 32 allows the escapement wheel 12 and the escapement rocker 14 to interlock with each other. The escapement wheel 12 and the escapement rocker 14 are in an output rest position. The balance plate 16 continues its course in the direction S1 then reverses its direction of rotation, which becomes S2, under the action of the return spring 4 of the balance 2.

Then, as shown in figure 9 , the pin 26 of the balance plate 16, rotating in the direction S2, comes into contact with the inner surface 42a of the other horn 42 of the fork 20 to cause the escapement rocker 14 to pivot and disengage the escapement wheel 12 of the second resting surface 32 ( figure 10 ). Long tooth 38b reaches pulse surface 34 and cooperates with it to impart a pulse to escapement flip-flop 14 ( figures 11 and 12 ). This impulse is transmitted from the escapement rocker 14 to the balance plate 16 by the interaction between the fork 20 and the pin 26.

After this impulse, another short tooth 36b of the escapement wheel 12 abuts against the first resting surface 30 of the escapement rocker 14 and the balance plate 16 continues its travel in the direction S2 until reversing from again its direction of rotation under the action of the return spring 4 of the balance wheel 2. The escapement 10 then finds itself in the state illustrated in picture 3 and the cycle repeats.

In this escapement 10, like the escapement described in the patent EP 2941673 B1 and as shown in figure 13 , the angle α between the entry and exit rest positions of the escapement wheel 12 is smaller than the angle β between the entry rest position of the escapement wheel 12 and the axis imaginary axis of rotation of the escapement rocker 14, these angles being seen from the imaginary axis of rotation of the escapement wheel 12. This feature makes the escapement 10 compact in plan view.

The alternation of short and long teeth 36, 38, and the fact that the short teeth 36 cooperate exclusively with the first resting surface 30 while the long teeth 38 cooperate with the second resting surface 32, the impulse surface 34 and the impulse tooth 28, allow the escapement lever 14 to be better balanced and therefore the escapement 10 to be less sensitive to shocks and to variations in the orientation of the watch with respect to the force gravitational.

The self-starting tooth 46 carried by the balance plate 16 facilitates the restarting of the escapement 10 when the disarming of the driving member (typically a barrel spring) of the watch movement causes the torque on the escapement 12 is no longer sufficient to overcome the resistance of the return spring 4 of the balance 2 during the impulse, causing the stoppage of the escapement 10. It is possible to adjust the neutral angular position of the balance 2, this that is to say the angular position at which the torque of the return spring 4 of the balance wheel 2 is zero, so that the escapement 10 always stops in a position where a long tooth 38 of the escapement wheel 12 is located between the impulse tooth 28 and the self-starting tooth 46 of the balance plate 16. When the driving member is reset, the escapement wheel 12 starts moving again and the long tooth 38 which is located between the impulse and self-starting teeth 28, 46 cooperate with the self-starting tooth 46 for drive the balance plate 16 in the direction S1 and restart the oscillation of the balance 2, without the user needing to shake the watch.

The balance plate 16 is in two levels, as shown in the figure 14 . On a first level, it comprises a circular body 48 and, on the periphery thereof, the impulse and self-starting teeth 28, 46 and a radial protuberance 50. A second level comprises the pin 26 projecting from the end of the radial protrusion 50 in the axial direction of the balance plate 16, a truncated circular body 52 aligned with the circular body 48 and, between the pin 26 and the truncated circular body 52, a clearance 54.

The balance plate 16 can be obtained, for example, by multi-level deep reactive ion etching (DRIE) of a silicon substrate, by etching on both sides of a silicon-on-insulator (known as SOI) substrate or by mono -level of two separate silicon substrates then assembly of the two substrates etched by fusion (“fusion bonding”) or another appropriate technique. Materials other than silicon can of course be used. In a variant of the invention, the impulse and self-starting teeth 28, 46 could be in the form of pallets embedded in the circular body 48.

The clearance 54 allows the horns 40, 42 of the fork 20 to pass behind the peg 26 during the clearance phases and the indirect impulse phase (cf. figure 4 , 10 and 12 ). This gives more freedom in the design of the exhaust.

The circular part of the periphery of the truncated circular body 52 serves as a stop on the reverse of the horns 40, 42 in the event of an impact to prevent the overturning of the escapement rocker 14 from one of its rest positions to the other when the pin 26 is outside the fork 20. The truncated circular body 52 and the reverse of the lugs 40, 42 advantageously replace the small notched plate and the stinger of traditional escapements and reduces the number of levels (from three to two) of the plate of balance wheel and therefore the height of the escapement.

The escapement rocker 14 is also in two levels, with a first level comprising the body 14a and the arms 22, 24 and a second level comprising the fork 20. The fork 20, thus raised with respect to the body 14a, can cooperate with the second level 26, 52 of the balance plate 16 without risk of colliding with the escapement wheel 12 or with the impulse and self-starting teeth 28, 46.

In accordance with the invention and with reference to the figure 1 , the balance plate 16 is returned relative to the conventional position of a balance plate. In other words, its second level 26, 52 is on the side of the balance 2 while the first level 48, 46, 28, 50 is on the side of the plate 5. The pin 26 is therefore directed towards the balance 2, this which allows the fork 20 to be placed close to the balance wheel 2, in a space between the upper part, 29a, of the escapement bridge 29 and the balance wheel axis 3. In this way, the escapement rocker 14 n does not increase the size of the oscillator in height despite its construction on two levels, and this without having to fix the pin 26 directly on the balance 2.

Advantageously, in the event of a major shock received by the timepiece while the escapement rocker 14 is in any one of its two rest positions, this shock causing an unlocking between the escape wheel 12 and the escapement rocker 14 driving escapement rocker 14 beyond this rest position, fork 20 can abut against upper part 29a of escapement bridge 29 and thus limit its rotation.

The present invention is also applicable to the escapement described in the patent EP 2941673 B1 , other semi-direct impulse escapements, as well as other types of escapements such as the Swiss lever escapement.

Claims (9)

Horological oscillator comprising a balance (2) mounted on a balance shaft (3), a balance plate (16) mounted on the balance shaft (3) and carrying a pin (26), and an escapement rocker ( 14) comprising a body (14a) mounted on an escapement rocker shaft (15) and a fork (20) at one end of the body (14a), the body (14a) extending over a first level and the fork (20) extending over a second level, the fork (20) being arranged to cooperate with the pin (26) in order to maintain the oscillations of the balance (2), the pin (26) protruding from the balance plate (16) parallel to the balance shaft (3), characterized in that the pin (26) is directed towards the balance (2). Horological oscillator according to Claim 1, characterized in that the escapement rocker (14) is stingless. Horological oscillator according to Claim 2, characterized in that the balance plate (16) comprises, on the same level as the pin (26), a truncated circular body (52), the periphery of which serves as a stop for the fork (20) in the event of a shock received by the clock oscillator when the pin (26) is outside the fork (20), to prevent the escapement rocker (14) from overturning. Horological oscillator according to Claim 3, characterized in that the balance plate (16) comprises, between the truncated circular body (52) and the pin (26), a clearance (54) able to receive part of the fork (20 ). Horological oscillator according to any one of Claims 1 to 4, characterized in that the fork (20) is situated at least partly in a clearance between the balance shaft (13) and an upper part (29a) of a bridge (29) in which one end of the escapement rocker shaft (15) pivots. Watchmaker oscillator according to Claim 5, characterized in that the fork (20) is arranged to abut against the upper part (29a) of the bridge (29) during a shock received by the watchmaker oscillator while the escapement lever (14) is in a rest position and causing an unlocking between the escapement wheel (12) and the escapement rocker (14) driving the escapement rocker (14) beyond this rest position. Horological oscillator according to any one of Claims 1 to 6, characterized in that the escapement rocker (14) and the balance plate (16) form part of a semi-direct impulse escapement. Horological oscillator according to Claim 7, characterized in that the semi-direct impulse escapement further comprises an escapement wheel (12) and in that the angle (a) between entry rest positions and exit of the escapement wheel (12) is smaller than the angle (β) between the entry rest position of the escapement wheel (12) and the imaginary axis of rotation of the escapement lever (14), these angles (α, β) being seen from the imaginary axis of rotation of the escape wheel (12). Timepiece, for example a watch, comprising a horological oscillator according to any one of Claims 1 to 8.

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