CH708724A2 - escape mechanism for watch movement. - Google Patents

Abstract

Exhaust mechanism for a watch movement comprising an anchor with a fork, and a shelf device coupled to a pendulum. The tray device comprises a dowel (10) on a large tray and a small tray (8). The fork includes a first horn (19) and a second horn (21). The pin (10) includes a first cam portion (12) configured to engage an engagement surface (23) of the first horn (19), and a second cam portion (14) configured to engage a engagement surface (25) of the second horn (21). Engagement surfaces engaging the cam portions include a non-planar geometric profile.

Description

Description

The present invention relates to an escapement mechanism of a watch movement, including a type of escapement Swiss anchor or anchor. The invention relates more particularly to the optimization of the assembly constituted by the plate pin and the fork of the anchor.

The assembly consisting of the plate pin and the fork of the anchor allows the release of the anchor of a tooth of the wheel of the exhaust mechanism and the impulse of the pendulum. During the impulse, the plate pin, which is connected to the balance, and the fork of the anchor, allow the transmission of energy from the anchor to the balance at each alternation.

A conventional system consists of a circular pin called "half-moon" with a portion of the circle that is removed to allow the ankle to enter the fork with sufficient security. The fork is in the form of a rectangular notch, the contact surfaces with the peg being flat.

Depending on the oscillation frequency of the pendulum, the amplitude of rotation of the anchor and the position of its axis of rotation, or other dimensions, there is inevitably some slippage between the ankle and the range in conventional systems. The surfaces in contact between the fork and the peg are identical for the clearance and for the impulse, namely, the pair of surfaces in contact during the release of the first alternation is identical to the pair of surfaces in contact during the impulse of the second alternation. However, a geometry that would be optimized for the release function might not be optimized for the pulse function. In conventional systems, the geometry of the ankle and fork assembly is therefore not optimized.

[0005] The optimization of the geometry of the contact surfaces between the ankle and the fork is intended in particular to reduce friction in order to reduce wear on the parts, or to reduce energy losses in order to increase the efficiency of the device. exhaust.

An object of the invention is to provide a precise and reliable watch exhaust mechanism over a long period of use.

It is advantageous to provide a watch exhaust mechanism with very low wear.

It is advantageous to provide a watch exhaust mechanism with very low energy consumption and therefore having a high efficiency.

[0009] It is advantageous to provide a compact and robust exhaust mechanism.

Objects of the invention are realized by a watch exhaust mechanism according to claim 1. The dependent claims describe advantageous aspects of the invention.

In the present invention, a watch exhaust mechanism for a watch movement comprises an anchor with a fork and a tray device with an ankle coupled to a rocker, the fork comprising a first horn and a second horn. The plug includes a first cam portion configured to engage an engagement surface of the first horn, and a second cam portion configured to engage an engagement surface of the second horn. According to one aspect of the invention, the engagement surfaces engaging the cam portions - i.e. the active surfaces - comprise a non-planar geometric profile, configured to reduce slippage during release functions. and impulse.

This allows to better optimize the profiles of the active surfaces on the ankle and also on the fork to eliminate or minimize friction between these bodies. It is desired to have a rolling movement without sliding between the parts of the ankle and the fork coming into contact.

According to a preferred embodiment, in a direction of rotation of the balance the first horn functions as the input horn and the second horn as the output horn, and in the opposite direction the first horn operates in as the output horn and the second horn as the input horn. However, the invention also extends to escape mechanisms having a single clearance and pulse per cycle of round-trip of the balance, and in this case one of the horns functions only as an input horn and the other only as an output horn.

According to one embodiment, the engagement surface may comprise a first portion and a second portion, the first and second portions being interconnected by a surface portion not coming into contact with the cam portions of the ankle. In other words, the contact surface is discontinuous (includes a jump). The cam surfaces and engagement surfaces are configured so that the first portion of the engagement surface of the input horn operates at least in part a release function of one pallet of the anchor, and the second portion of the engagement surface of the output horn operates at least in part a pulse function of said pallet of the anchor. In a variant, the second portion of the engagement surface of the input horn operates at least in part also a release function of said pallet of the anchor. In a variant, the first portion of the engagement surface of the output horn operates at least in part also a pulse function of said pallet of the anchor. This embodiment with discontinuous contact surfaces offers more possibilities for optimizing the geometrical profiles of the active surfaces during the release and impulse operations.

In a variant, the engagement surfaces comprise two portions, each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion of each engagement surface operates mainly in a function of clearing a pallet from the anchor, and that the second portion of each engagement surface operates primarily a pulse function of a pallet of the anchor.

In one embodiment, each of the cam portions of the peg comprises a geometric profile defined by a discontinuous function in its first or second derivative. In a variant, a portion of the cam portions never come into contact with the engagement surfaces. In one embodiment, the cam portions comprise two portions, each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion of each engagement surface operates primarily a clearance function. a pallet of the anchor, and that the second portion of each engagement surface operates primarily a pulse function of a pallet of the anchor.

The geometric profiles of the engagement surfaces and the cam portions of the dowel may comprise at least a portion corresponding to a gear tooth profile.

In one embodiment where the release and the impulse pallets of the anchor are performed in both directions of rotation of the tray device, that is to say, each half-cycle oscillation of the balance, the engagement surfaces of the fork contacting the ankle may be symmetrical with respect to a median plane of the fork. The cam surfaces on one side of the peg may be symmetrical to the cam surfaces on the other side of the peg so as to have an identical engagement between the peg and the fork in both directions of rotation of the peg.

In one embodiment, the range may advantageously be achieved by a deposition process such as by photolithography, or by other manufacturing processes used in the semiconductor industry, of a silicon-based material. . This makes it possible to obtain surface profiles of complex shapes with great precision.

In an advantageous embodiment, the geometric profile of the engagement surface comprises a gear profile. The peg may advantageously also comprise a complementary gear profile.

In a first variant, the gear profile is an involute profile of a circle. This profile can be automatically defined by specifying values of the module (for example 0.2) and the number of virtual "teeth" equivalent that would have the ankle and anchor (for example respectively 6 and 21) if they were part of a train.

In a second variant, the gear profile is a profile according to the NIHS standard (Swiss Watch Industry Standard), for example the NIHS20-25 standard.

The peg may comprise a conventional shape, such as a half-moon shape. The ankle may, however, include other profiles optimized in complementarity with the profile of the engagement surfaces to eliminate or minimize sliding during release and pulse contacts.

Other objects and advantageous aspects of the invention will appear on reading the claims, as well as the detailed description of the embodiments below, and the appended drawings, in which:

Fig. 1 is a schematic perspective view of an escapement mechanism of a watch movement, according to one embodiment of the invention;

Fig. 2a is a view of a fork-peg structure of an exhaust mechanism according to one embodiment of the invention;

Fig. 2b is a view of a fork-peg structure of an exhaust mechanism according to a variant of the embodiment of FIG. 2a;

Fig. 3 is a graph showing the work (or energy) of abrasion as a function of the curvilinear abscissa of the surface of the fork in contact with the ankle, illustrating a comparison for three types of geometries: (i) circular ankle and traditional range, (ii) NIHS profile and (iii) involute profile.

Fig. Figure 4 is a graph of the torque given by the pendulum anchor, resulting from the FEM simulation in static mode, illustrating a comparison for the three types of geometries: (i) circular ankle and traditional range, (ii) NIHS profile and (iii) ) involute profile of a circle.

Fig. 5a is a view of a fork-plug structure of an exhaust mechanism according to another embodiment of the invention, in a first pulse phase;

Fig. 5b is a view similar to that of FIG. 5a showing a second pulse phase.

Referring to the figures, an escape mechanism for a watch movement comprises a wheel 5 with teeth 9, an anchor 7, and a plate device 4 coupled to a rocker 2.

The anchor comprises a fork 13, pallets 17a, 17b, and a rod 15 interconnecting the pallets with the fork. The rod is rotatably coupled to the chassis by a pivot 1 1. The vanes engage the teeth 9 of the wheel which is connected to a power source providing a torque on the wheel. One pallet forms the entry pallet 17a and the other constitutes the exit pallet 17b. The anchor comprises a stinger 27 fixed on the fork by means for example of a shaft driven into a fixing hole at the base of the fork. The illustrated mechanism corresponds to an escapement of Swiss anchor type. As this principle is well known, the conventional elements and their operation will not be described in more detail here.

The tray device 4 comprises a large plate 6 with an ankle 10 and a small plate 8 provided with a notch 16 for the passage of the dart. The pin 10 comprises on one side a first cam portion 12 and on the other side a second cam portion 14. In the direction of rotation of the beam shown in Figs. 2a and 2b (first half), the first cam portion 12 functions as the input cam and the second cam portion as the output cam. The rocker having an oscillating movement, in the other direction of rotation (second alternation) the functions of the first and second cam parts are reversed.

The fork 13 comprises a first horn 19 and a second horn 21. In the direction of rotation of the balance shown in Figs. 2a and 2b (first alternation), the first horn 19 functions as the input horn and the second horn as the output horn. In the other direction of rotation (second alternation), the functions of the first and second horns are reversed.

The first cam portion 12 of the ankle is configured to engage an engaging surface 23 of the first horn, and a second cam portion 14 is configured to engage an engaging surface 25 of the second horn. Engagement surfaces engaging the cam portions include a non-planar geometric profile.

In a variant, as illustrated in FIGS. 5a, 5b, the engaging surfaces 23, 25 comprise a first portion 23a, 25a and a second portion 23b, 25b, the first and second portions being interconnected by an intermediate surface portion 23c not coming into contact with the parts ankle cam. There is therefore a discontinuity (a jump) in the surfaces of the ankle and the fork coming into contact. Each portion of the engagement surfaces may comprise a geometric profile defined by a continuous function in its first or second derivative. The engagement surfaces may be configured so that the first portion of each engagement surface operates primarily a release function of a pallet of the anchor, and that the second portion of each engagement surface operates primarily a function of impulse of a pallet of the anchor.

In a non-illustrated embodiment, each of the cam portions of the peg comprises a geometric profile defined by a discontinuous function in its first or second derivative. An intermediate portion of the cam portions never comes into contact with the engagement surfaces. The cam portions can comprise two portions, each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion of each engagement surface operates primarily a release function of a pallet. the anchor, and that the second portion of each engagement surface operates primarily a pulse function of a pallet of the anchor.

[0032] One aspect of this invention is the use of adapted, curved and simultaneously optimized tooth profiles of the active surfaces, i.e. contact surfaces, ankle and fork of the anchor. Different typologies of profile can be adapted to the dowels and fork depending on the pointing of the escapement and the frequency of the oscillator. Non-exclusively, two types of specific gear wheels can advantageously be used:

1 <er> profile type: NIHS (Fig 2a)

By way of example, a profile known as NIHS defined according to the NIHS20-25 standard can be used for a transmission of module 0.2 with the following parameters:

- Number of sprocket teeth (balance plate) = 6

- Number of tooth wheel (anchor) = 21

- Head diameter = 4.704 mm

- Foot diameter = 3.5 mm

- Thickness of tooth = 0.282 mm

- Radius of the warhead = 0.4032 mm

- Radius to the bottom of the tooth = 0.1526 mm

2 <eme> type of profile: involute of circle (fig 2b)

This profile is automatically defined according to the module (for example module 0.2) and numbers of teeth of the pinion and the wheel (for example 6 and 21 respectively).

The use of a suitable tooth profile makes it possible to considerably limit sliding between the two surfaces in contact, in particular at the beginning of the pulse phase (see Fig. 3). Indeed, the traditional fork / pin system has a significant slip at the beginning of the pulse which explains why the abrasion work (product of the sliding distance by the tangential force to the contact) is higher than for the other two systems (NIHS profiles and circle involute). The reduction of the sliding distance at the beginning of the pulse makes it possible to reduce the risk of wear and therefore to increase the torque on the escape wheel. In conventional mechanisms, these phenomena limit the evolution of the movements. The increase of the energy transmissible via the escapement makes it possible to maintain movements having a higher energy (and therefore a regulating power), for example of the order of 1 mJ, whereas the traditional movements have an energy of the order of 0.1 mJ.

The mechanism according to the invention is particularly advantageous for oscillators with relatively low frequency, for example less than or equal to 4 Hz, and having a high inertia, for example greater than 10 mg cm 2, and / or equipped with a system for shortening the catching of the anchor.

FIG. 3 illustrates the abrasion work as a function of the curvilinear abscissa of the ankle-contacting fork surface for three types of geometries: (i) circular ankle and traditional range, (ii) NIHS profile and (iii) profile in involute of circle. In these examples the abrasion work for NIHS and circle-involute profiles is reduced by a factor of about three at the beginning of the function compared to the traditional profile. It follows that the energy transmitted to the balance (and therefore the regulating power) can be higher without introducing an additional risk of wear.

The torque applied by the anchor to the balance, which is related to the yield, is almost equivalent by using tooth profiles for the transmission fork / peg while the 1 <ere> pulse occurs on a larger angle ( see Fig. 4). In other words, the total energy transmitted to the balance (area under the curve) is greater or equal using tooth profiles. The results in fig. 3 and fig. 4 allow to estimate that, by exploiting this invention, the energy (and therefore the regulating power) of a movement could be increased without introducing an excessive risk of wear of the components concerned.

FIG. 4 illustrates the torque given to the balance according to the position of the latter during the first pulse function for the three types of geometries: (i) circular pin and traditional range, (ii) NIHS profile and (iii) profile in involute circle. At the available torque on the escape wheel, the optimized profiles make it possible to transmit almost the same torque to the balance wheel but to a higher angular interval (from 1 ° to 3 ° additional). The total energy transmitted to the pendulum (integral curves) during the first pulse of the first alternation is therefore greater or equal using these profiles.

3 <eme> type of profile: multi-profile shape (Fig. 5)

According to one variant, the transmission properties of each of the solutions in the pulse phase are used where they are the most effective. The principle of this third solution is to combine at least two types of profile for the range but also for the plateau pin. Thus, the contact during the first part of the pulse is effected on a first type of profile with less sliding and the contact during the second part is performed on another profile. In the example illustrated in FIG. 5, the first part of the pulse (FIG 5a) is effected for example with an involute type profile of a circle while the second part (FIG 5b) is performed with a traditional fork / ankle geometry (circular ankle). and flat fork).

The invention can also be used in escapements with anchors of the English type, coaxial or other escapements of known types.

The advantages of the invention include a reduction in the risk of wear at the ankle, in particular for the anchor-pendulum quick-catch systems, and the possibility of simultaneously increasing the available torque at anchor and the anchor. angular pulse interval (thus the energy transmitted to the movement) without increasing the risk of wear.

List of references [0043] pendulum 2 an escape mechanism 3 a wheel 5 tooth 9 an anchor 7 pivot 1 1 fork 13

5

Claims (15)

first horn (input horn) 19 engagement surface 23 first portion 23a second portion 23b intermediate portion (discontinuity) 23c second horn (output horn) 21 engagement surface 25 first portion 25a second portion 25b intermediate portion (discontinuity) 25c dard 27 stick 15 pallets 17 input pallet 17a output pallet 17b device tray 4 large tray 6 peg 10 first cam part (cam input) 12 second cam part (output cam) 14 small tray 8 notch claims An escapement mechanism (3) for a watch movement comprising an anchor (7) with a fork (13) and a tray device (4) with a peg coupled to a pendulum (2), the range comprising a first horn (19) and a second horn (21), the pin comprising a first cam portion (12) configured to engage an engagement surface (23) of the first horn, and a second cam portion (14) configured to engaging an engaging surface (25) of the second horn, characterized in that said engaging surfaces engaging the cam portions comprise a non-planar geometric profile. 2. Exhaust mechanism according to claim 1, characterized in that each of said engagement surfaces (23, 25) has a geometric profile defined by a discontinuous function in its first or second derivative. 3. Exhaust mechanism according to the preceding claim, wherein at least one intermediate portion (23c, 25c) of the engagement surfaces never comes into contact with the cam portions of the dowel. 4. Exhaust mechanism according to claim 2 or 3, characterized in that the engagement surfaces comprise two portions (23a, 23b; 25a, 25b), each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion (23a, 25a) of each engagement surface operates primarily a release function of a pallet of the anchor, and that the second portion (23b, 25b) of each surface of engagement mainly operates a pulse function of a pallet of the anchor. An escapement mechanism according to claim 1, characterized in that each of said cam portions (12, 14) of the dowel comprises a geometric profile defined by a discontinuous function in its first or second derivative. 6 6. Exhaust mechanism according to the preceding claim, wherein at least a portion of the cam portions never come into contact with the engagement surfaces (23, 25). 7. Exhaust mechanism according to claim 5 or 6, characterized in that the cam portions comprise two portions, each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion ( 23a, 25a) of each engagement surface operates primarily a release function of a pallet of the anchor, and that the second portion (23b, 25b) of each engagement surface operates primarily a pulse function of a pallet of the anchor. Exhaust mechanism according to one of the preceding claims, characterized in that the geometric profiles of the engagement surfaces (23, 25) and the cam portions of the dowel (12, 14) comprise at least one corresponding part. to a gear tooth profile. 9. Exhaust mechanism according to the preceding claim, characterized in that the gear profile is an involute profile of a circle. 10. Exhaust mechanism according to claim 8, characterized in that the gear profile is a profile according to the NIHS standard. Exhaust mechanism according to one of the preceding claims, characterized in that the first cam portion is symmetrical to the second cam portion. 12. Exhaust mechanism according to one of the preceding claims, characterized in that the fork and the peg are made of a silicon-based material or derived from silicon. 13. Exhaust mechanism according to one of the preceding claims, characterized in that the fork and the peg are made by a photolithography process or a LIGA process. 14. Exhaust mechanism according to one of the preceding claims, characterized in that the fork and the peg are made of a nickel-based material. 15. Watch movement comprising an exhaust mechanism according to one of the preceding claims. 7