CH703833A2 - Anti-tripping hairspring for detent type timepiece escapement, has blocking units for blocking consecutive spiral-turns when rotation amplitude of hairspring from balance position to extreme position reaches determined angle - Google Patents

Abstract

The hairspring (1) has blocking units for blocking consecutive spiral-turns (13) when rotation amplitude of the hairspring from a balance position to an extreme position reaches a determined angle, where the hairspring is made of silicon or metal. The blocking units have transversal segments (15) fixed to the consecutive spiral-turns. The segments are angularly offset in the balance position so as to abut against each other when the amplitude of the hairspring from the balance position to the extreme position reaches the determined angle. An independent claim is also included for a timepiece escapement.

Description

Description

The present invention relates to an anti-gallop hairspring for a clock escapement without stop, the type of escapement trigger.

[0002] The phenomenon of galloping is well known to those skilled in the art. It mainly concerns relaxation exhausts, and strongly harms when it occurs, to the precision of a timepiece that is equipped.

Relaxation exhausts are particularly used in precision timepieces because they disturb the isochronism of the oscillator less than the Swiss anchor escapements. For a detailed description of such an escapement, reference is made to the book "Theory of watchmaking", chapter 6.7.1. We will confine ourselves here to recalling the principle of the phenomenon of galloping of which it is the object.

In a detent escapement, the balance-balance oscillator oscillates between two extreme positions, a so-called 'high' position and a so-called 'low' position. Each of its oscillations comprises a so-called 'ascending' alternation, during which it moves from the low position to the high position, and a so-called 'downward' alternation, during which it switches from the high position to the low position. The escape wheel delivers to the oscillator sprung-balance, an oscillation pulse, during the upward alternation, in a so-called "equilibrium" position, substantially halfway between the high position and the low position. During the downward alternation, the sprung balance receives no impulse. It will be noted that the ascending and descending alternations are indifferently associated with the contraction or the radial extension of the hairspring.

The amplitude of each alternation, namely the angular displacement of the oscillator from the equilibrium position to the high or low position, is typically 330 °. During an impact, the sprung balance may receive an excess of energy and its amplitude exceeds this value, and even exceeds 360 °, a limit value beyond which the sprung balance receives an additional impulse. . The upward alternation can then count two pulses, while the downward alternation can count one. The escape wheel, which normally performs a step by oscillation, then performs two or even three steps during a single oscillation. This phenomenon of runaway balancespiral, which is self-maintenance, is called gallop. It hinders the precision of the movement, because for each additional step made by the escape wheel, the measurement of the time advance of a duration inversely proportional to the oscillation frequency of the spiral balance.

Various locking mechanisms exist to remedy the gallop balance-spiral. These mechanisms are designed to block the rotational movement of the sprung balance beyond a given angle of 330 °. One of them, described in patent application EP 1 801 669, comprises a pinion integral in rotation with the balance spring. Said pinion meshes with a toothed sector, pivotally mounted, and provided with two terminal spokes may abut against a fixed stop if the rocker is driven beyond a given angle of rotation. This device proves effective to prevent the oscillator from racing, and this in both directions of rotation, nevertheless it generates losses at the level of the gearing between the pinion and the toothed sector, which disturb the isochronism of the sprung balance. Another mechanism disclosed in application EP 1 645 918 comprises an arm mounted radially on the last turn of the spiral, which is interposed between a finger integral with the balance and two columns mounted on a balance bridge, when the balance-balance exceeds some angular and radial extension. This device is difficult to implement, mainly because of the extreme precision required for its assembly.

The present invention provides a simple and robust alternative to existing anti-gallop devices. More specifically, it relates to an anti-gallop hairspring for a clock escapement, intended to oscillate between two extreme positions, passing through an equilibrium position, and comprising a plurality of turns. According to the invention, it further comprises means for locking at least two consecutive turns when its amplitude of rotation from the equilibrium position to at least one of the extreme positions reaches a determined angle ψ.

In an advantageous embodiment, these means comprise transverse segments, integral with consecutive turns, angularly offset to abut against each other when the rotation amplitude of the spiral according to the invention, since said equilibrium position to at least one of the extreme positions reaches a certain angle Ψ-

Thanks to these transverse segments, the hairspring is braked or blocked in its rotation without the use of external means likely to disturb its isochronism.

The present invention also relates to a clockwork escapement provided with such an anti-gallop spiral.

Other features and advantages of the present invention will emerge from the description which follows, made with reference to the accompanying drawings, and giving by way of explanatory example, but in no way limiting, some advantageous forms of the realization of a anti-gallop spiral for a timepiece, drawings in which:

- figs. 1 and 2 are top views of a first embodiment of an anti-galling hairspring according to the invention, respectively in the equilibrium position and in the locking position,

- fig. 3 illustrates a variant of this first embodiment of such a spiral,

2 - FIG. 4

- fig. 5 shows an advantageous form of the first embodiment of an anti-gallop hairspring according to the invention, in the locking position, is a detail view of the hairspring shown in FIG. 4

- figs. 6 and 7 are top views of a second and a third embodiment of an anti-gallop hairspring according to the invention, configured to achieve a contraction lock,

- figs. 8 and 9 illustrate these same second and third embodiments of the anti-gallop hairspring according to the invention, configured, this time, to achieve a blockage in extension, and

- fig. 10 represents an anti-gallop hairspring according to the invention combining the features of embodiments 7 and 9.

The anti-gallop balance spring shown in equilibrium in FIG. 1, 3, 6, 7, 8, 9 and 10 and referenced as a whole 1, is generally formed of a blade 10 wound on itself in spiral, so as to have an angular elasticity. The central end 1 1 of the blade 10 is fixed in a known manner on a shell 20 driven on a balance shaft 21, while its peripheral end 12 is intended to be fixed to a not shown cock. From one end to the other, the hairspring 1 comprises a plurality of turns 13, typically between 10 and 15, having between them, in equilibrium, a pitch p.

According to the invention, the hairspring 1 further comprises a plurality of transverse segments 15, 15 <'>, 15 <"> a, 15 <"> b, 15 <"> c secured to successive turns 13 , and arranged angularly to abut one on the other, when the amplitude of rotation of the spring 1 exceeds a determined angle ψ between 300 ° and 360 °, from its equilibrium position to one of its extreme positions.

In the embodiment shown in FIG. 1 to 5, the hairspring 1 is formed, from the central end 1 1, of a first spiral portion 14a of connection to the ferrule 20, then a succession of spiral portions 14 of pitch p, connected together by transverse segments 15 of length I, and finally, a last spiral portion 14b of connection to a rooster. Preferably, the segments 15 extend radially, but, alternatively, they may be slightly inclined relative to the radial orientation. By construction, the initial radius of a spiral portion 14 is equal to the final radius of a preceding portion 14 increased by the length I of a segment 15. The successive transverse segments 15 are arranged angularly to abut one against the other when the amplitude of the alternation associated with the contraction of the hairspring 1 reaches a determined value ψ of between 300 ° and 360 °.

To this end, the various parameters of the spiral 1, in its equilibrium position, are linked by geometric relationships explained below. N is the number of turns 13 of the hairspring 1, from the central end 1 1 to the peripheral end 12, Rnle radius of the nth turn 13, R 1 and RN, respectively the radii of the first and the last turn 13. It is still noted θηle angular offset at equilibrium, with respect to the radially aligned position, between the transverse segments 15 associated respectively with the nth and n + 1 th coils 13, and Φηle angular sector of the nth spiral portion 14.

It is known that the amplitude of rotation of the spring 1, from its equilibrium position to one of its extreme positions, is not distributed evenly over all the N turns 13, the turns 13 large radius absorbing a greater part of the amplitude of rotation than the turns 13 of small radius. It can be shown that for a rotation amplitude of the spiral 1 given, each turn 13 is deformed by an angle proportional to its radius Rn. It follows that the radial segments 15, associated respectively with the nth and n + 1th turns, are aligned radially when the amplitude associated with the contraction of the hairspring 1 takes the determined value ψ, if the angular offset θη between them, at 1 balance, obeys the relationship:

The angular sector Φηd'une nth spiral portion 14 is the complement of the angular offset θη between the radial segments 15 associated respectively with the nth and n + 1 th turns 13. 11 thus obeys the following relationship:

Φη 360

Ψ

NOT

R

RN RI

For example, for a number of turns equal to 10, as illustrated in FIG. 1 and 2, and an angle ψ equal to 320 °, there are 1 1 portions of spirals 14 and 12 radial segments 15. The angular offsets θη between radial segments vary from 16 °, from the central end 1 1, to 41 ° to 1 °. peripheral end 12, while the angular sectors Φηde spiral portions 14, from 344 ° to 319 °.

Finally, so that two consecutive segments 15 come into abutment against each other when the amplitude of the alternation reaches the determined value ψ, it is necessary that their length I is sufficient. As it is known

3 of the skilled person, the pitch p of a hairspring 1 decreases, when it contracts, a value which depends on the amplitude of the alternation and the number N of turns 13. The segments 15 are therefore contact if the length I of the segments 15 verifies the relation:

2p> I> p

When the preceding rules of construction are applied, the transverse segments 15 abut against each other beyond a determined rotation angle contraction ψ, as shown in FIG. 2. The turns 13 are then locked in rotation relative to each other and the hairspring 1 has more or almost no angular elasticity. Its rotation movement is suddenly blocked. The galloping phenomenon is thus avoided in the alternation associated with the contraction of the hairspring 1. This alternation will preferably be the upward alternation, because the phenomenon of galloping occurs more frequently during this alternation.

It should be noted here that it may be sufficient to brake. the rotation of the hairspring 1 in case of shock, rather than block it. In this case, the hairspring 1 is formed, at least, of a first spiral portion 14a of any angular sector, a second spiral portion 14 of angular sector and a third spiral portion 14b of any angular sector. The three spiral portions 14 are interconnected by two transverse segments 15 abutting one another when the determined angle ψ is reached. In this case, only two consecutive turns lock in rotation relatively to one another, thus slowing the general movement of rotation of the spring 1, instead of blocking it. Such a variant of the first embodiment is illustrated in FIG. 3. By extension, the spiral 1 may comprise two, three and up to N 'spiral portions 14, and, respectively, three, four and up to N' + 1 transverse segments 15, N 'being a function of the number N of turns 13 and the angle ψ. The braking of the hairspring 1 increases with the number of spiral portions 14 and transverse segments 15, until complete locking of the hairspring when the number of spiral portions 14 takes the maximum value N '.

Referring now to FIGS. 4 and 5, which represent an advantageous form of the embodiment of the spiral 1 illustrated in FIG. 1 and 2. According to this variant, the segments 15 extend radially slightly beyond the two spiral portions 14 they connect, and have two fingers 16 and 17 at their ends, extending angularly outwardly of the portions of spirals 14 that they connect. As shown in detail in FIG. 5, the fingers 16 and 17 fit into each other when the segments 15 abut. The segments 15 are then locked radially relative to each other, which gives the hairspring 1, in addition to an angular rigidity, a radial rigidity, when the determined amplitude ψ is reached. The locking spiral 1 is ensured even during violent shocks, because the radial elasticity does not compensate, in this case, the angular rigidity.

In fig. 6 and 7, there is shown, respectively, a second and a third embodiment of the spiral 1 according to the invention.

The spiral 1 illustrated in FIG. 6 and 7, is distinguished from the embodiment described with reference to FIGS. 1 and 2, in that it is formed of a single spiral portion 14, from the central end 1 1 to the peripheral end 12, of which transverse segments 15 '' and 15 'are integral with each other. "> a and 15 <"> b.

According to the first variant shown in equilibrium in FIG. 6, the transverse segments 15 ''> are of length I greater than or equal to p and less than or equal to 2p, and are integral with the single spiral portion 14 by their middle. They extend substantially radially, but, alternatively, may also be slightly inclined relative to the radial orientation. In this case, the inclination must be chosen so as not to block the return to equilibrium of the hairspring 1, if the determined angle ψ is exceeded. At equilibrium, the angular offset θη between the transverse segments 15 'associated respectively with the nth and n + 1th turns 13, is, as stated above, while the angular sector Φηles separating is 360 When the rotation of the spiral 1 according to the invention exceeds the critical value ψ during the amplitude associated with its contraction, the segments 15 ''> are aligned radially and abut against each other. The hairspring 1 is then locked in rotation.

According to the variant shown in equilibrium in FIG. 7, the hairspring 1 comprises first transverse segments 15a and second transverse segments 15b, integral with the single spiral portion 14 by one of their ends. The first transverse segments 15a "point outwardly of the spiral 1, while the second transverse segments 15b" point towards the inside of the spiral 1. Both are of length I greater than or equal to p / 2, less than p.

Each turn 13, with the exception of the first and the last comprises a transverse segment 15 "" and a transverse segment 15 "b. The first turn 13 from the central end 1 1, has a single transverse segment 15 "" oriented outwardly, while the last has only one <"> b, facing inwards . The transverse segments 15a are radially aligned along a radius of the spiral 1 and the transverse segments 15b are offset from the segments 15a by an angle θη. The offset θ between a segment 15 Associated with an nth turn 13 and a segment 15 associated with an n + 1 th turn 13, is, as previously, the angular sector Φηles separating is equal to 360 ΐB HiWhen the rotation of the spring 1 according to the invention exceeds the determined value ψ during the amplitude associated with its contraction, the segments 15 "" abut against the segments 15 "b The spiral 1 is then locked in rotation.

As mentioned above, the transverse segments 15 <'> and 15 <"> a and 15 <"> b are at least two in number, for a braking effect of the hairspring 1, and not for locking. It will also be noted that, in an advantageous variant, the segments 15 '' and 15 '' '', 15 '' '' 'of the spiral 1 described with reference to FIGS. 6 and 7, comprise fingers 16 and 17 extending

4

Claims (10)

angularly and intended to fit into each other to impart radial rigidity to the hairspring 1 in the angular locking position. This effect has already been described previously with reference to FIGS. 3 and 4. Previously described embodiments of an anti-gallop hairspring 1 for locking during the alternation associated with its contraction. Generally, this is positive alternation, because the galloping phenomenon occurs preferably during this alternation. However, it can happen that the positive alternation is associated with the extension of the spiral. In this case, it is desired that the locking of the hairspring take place in extension and not in contraction. Figs. 8 and 9 illustrate a particular configuration of the spirals 1 shown in FIG. 6 and 7, allowing this effect. The hairspring 1 shown in FIG. 8 is distinguished from the spiral 1 described with reference to FIG. 6, in that the transverse segments 15 ''> are arranged to block it when the amplitude of its rotation exceeds a critical value ψ in extension and not in contraction. The principle of operation is identical, but the rules of construction are different. In particular, the equilibrium angular displacement θ between two transverse segments 15 associated with the nth and n + 1th turns 13 is well worth, but the angular sector Φηles separating is equal to Moreover, the pitch p of a 1, when it extends radially, a value which depends on the amplitude of the alternation and the number N of turns 13. The length I of the transverse segments 15 '' must then be provided so that they contact each other during the alternation associated with the extension. As an indication, we give the following relation: I = 1 .6p Thanks to these characteristics, each segment 15 ''> abuts against a consecutive segment 15 '' when the amplitude of rotation of the spiral 1 reaches a given angle ψ in extension, and the rotation of the spiral 1 is thus blocked. In the same way, the spiral 1 illustrated in FIG. 9 is distinguished from the spiral 1 described with reference to FIG. 6, in that it comprises segments 15a and 15c designed to block its rotation in extension and not in contraction. The transverse segments 15a "are aligned along a radius of the hairspring 1. The segments 15c" point, like the transverse segments 15b, inwardly of the hairspring 1, but they are distinguished by their position relative to the segments 15 <"> a The offset θη between a segment 15 <"> associated with an nth turn 13 and a segment 15 <"> c associated with an n + 1 th turn 13, is, as previously ΐ · -, but the angular sector Φη separating them is equal to the length I of the segments 15 <"> a and 15 <"> it is typically equal to 0.8p When the amplitude of rotation of the spiral 1 reaches the determined value ψ in extension, the segments 15 <"> abut against the segments 15 <"> c, and the spiral is then locked in rotation. [0033] Referring now to FIG. 10 showing a hairspring 1 intended to hang in extension and contraction when its amplitude of rotation reaches a determined value ψ. Said hairspring 1 combines the characteristics of the hairspring 1 shown in FIG. 7 and the spiral 1 shown in FIG. 9. It comprises first segments 15a, second segments 15b and third segments 15c positioned relatively to each other in the manner described previously described. a are thus aligned along a radius of the hairspring 1 and the transverse segments 15 <"> b and 15 <"> c are offset on either side of the segments 15 <"> a by an angle θη equal to When the amplitude of rotation of the spiral thus configured reaches the determined angle ψ, in contraction or extension, the segments 15 <"> a respectively abut against the segments 15 <"> b or 15 <"> c . The hairspring 1 according to the invention is made of a material having elastic properties. Preferably, because of its discontinuous structure, it will be chosen to manufacture silicon, by a photolithographic process well known to those skilled in the art. Alternatively, one can opt for a metal spiral, for example nickel, gold, or a nickel alloy and gold, obtained by a physico-chemical deposition process type liga. claims 1. Anti-gallop spiral (1) for a watch escapement, intended to oscillate between two extreme positions, via an equilibrium position, and comprising a plurality of turns (13), characterized in that it comprises, furthermore , means (15, 15 <'>, 15 <"> a, 15 <"> b, 15 <"> c) for locking at least two consecutive turns (13) when its rotation amplitude from the equilibrium position until at least one of the extreme positions reaches a certain angle ψ. 2. anti-gallop spiral (1) according to claim 1, characterized in that said means comprise at least two transverse segments (15, 15 <'>, 15 <"> a, 15 <"> b, 15 <"> c), integral with two consecutive turns (13), angularly offset in equilibrium position to abut against each other when the amplitude of rotation of the spiral (1) from said equilibrium position to at least one of the extreme positions reaches a certain angle ψ. 3. Anti-gallp spiral (1) according to claim 1, characterized in that said means comprise a plurality of transverse segments (15, 15 <'>, 15 <"> a, 15 <"> b, 15 <"> c), integral with a plurality of consecutive turns (13), angularly offset in equilibrium position to abut against each other when the rotation amplitude of the spiral (1) from said equilibrium position until at least one of the extreme positions reaches a certain angle ψ. 4. anti-gallop spiral (1) according to one of claims 2 and 3, characterized in that said transverse segments (15, 15 <'>, 15 <"> a, 15 <"> b, 15 <"> (c) are radial. 5. anti-gallop spiral (1) according to one of claims 2 to 4, characterized in that it comprises N turns (13) of radius R! Decreasing, and in that the angular offset θη at the equilibrium between a transverse segment (15, 15 <'>, 15 <"> a) associated 5 to an nth turn (13) and a transverse segment (15, 15 <'>, 15 <"> b, 15 <"> c) associated with an n + 1 th turn (13), is equal to S s3/ Where R is the radius of the nth turn (13). 6. anti-gallop spiral (1) according to claim 5, characterized in that the angular sector On from a transverse segment (15, 15 <'>, 15 <"> a) associated with an nth turn (13) up to to a transverse segment (15, 15 <'>, 15 <"> b) associated with an n + 1 th turn (13) is equal to 3604 7. anti-gallop spiral (1) according to claim 5, characterized in that the angular sector Φηdepuis a transverse segment (15 <'>, 15 <"> a) associated with an nth turn (13) to a segment transversal (15 <'>, 15 <"> c) associated with an n + 1 th turn (13) equals 360+ 8. anti-gallop spiral (1) according to one of claims 5 and 6, characterized in that it is formed of a plurality of spiral portions (14) of pitch p, of angular sector Φnegal 360- connected between them by said transverse segments (15). 9. An anti-gallop spiral (1) according to claim 8, characterized in that it is of pitch p, and in that said transverse segments (15) are of length I between p and 2p. 10. anti-gallop spiral (1) according to claim 9, characterized in that it further comprises two spiral portions (14a, 14b) of connection. 1 1. Anti-gallop spiral (1) according to one of claims 2 to 7, characterized in that it is formed of a single spiral portion (14) of which said transverse segments (15 <'>, 15 < "> a, 15 <"> b, 15 <"> c). 12. anti-gallop spiral (1) according to claim 1 1, characterized in that it is of pitch p, and in that said transverse segments (15 <'>) are of length I between p and 2p, and are integral with the turns (13) by their middle. 13. anti-gallop spiral (1) according to claim 1 1, characterized in that it is of pitch p, and in that said transverse segments (15 <"> a, 15 <"> b, 15 <"> c) are of length I between p / 2 and p, and are integral with said turns (13) at their ends. 14. An anti-gallp spiral (1) according to claim 13, characterized in that said transverse segments (15 <"> a, 15 <"> b, 15 <"> c) comprise first segments (15 <"> a ) pointing outwardly of the hairspring (1), and second segments (15 <"> b, 15 <"> c) pointing inwardly of the hairspring (1). 15. anti-gallop spiral (1) according to one of claims 1 to 14, characterized in that it is formed of silicon. 16. An anti-gallop spiral (1) according to one of claims 1 to 14, characterized in that it is formed of metal according to a type liga process. 17. Clock escapement comprising an oscillating member provided with a hairspring according to one of claims 1 to 16. 18. Clock escapement according to claim 17, characterized in that it has no abutment. 19. Clock exhaust according to claim 18, characterized in that it is of the expansion type. 6