This application claims priority from European Patent application 15201020.3 of Dec. 18, 2015, the entire disclosure of which is hereby incorporated herein by reference.
The invention concerns a regulating mechanism for dissipating energy superfluous to the achievement of the function of a timepiece mechanism including a functional wheel set.
The invention also concerns an escapement mechanism including such a regulating mechanism.
The invention also concerns a timepiece movement including at least one such regulating mechanism.
The invention also concerns a watch including such a movement, and/or at least one such regulating mechanism.
The invention concerns the field of timepiece mechanisms intended to be incorporated in a watch or in a mobile device.
Improving the efficiency of an escapement mechanism is a constant preoccupation in the watch industry. To this end, it is generally sought to minimise dissipation of any kind in an escapement, since dissipations are difficult to control and impair the efficiency of the oscillator. In particular, dissipation through accelerations, notably due to the actual working of the mechanism or through accelerations of external origin, particularly from shocks, and dissipation through friction are harmful and difficult to control.
Currently no system of controlled dissipation is used in escapement mechanisms.
CH Patent 704457 in the name of MONTRES BREGUET SA discloses a regulator for a timepiece wheel set or striking work, for regulating the pivoting speed, about a first pivot axis, of a wheel set comprising an inertia-block pivoting about a second pivot axis parallel to the first. This regulator includes means for returning the inertia-block to the first axis. When the wheel set pivots at a speed lower than a reference speed, the inertia block remains confined within a first volume of revolution about the first axis. When the wheel set pivots at a speed higher than the reference speed, the inertia-block engages, at least on a peripheral portion thereof, in a second volume of revolution about the first axis, contiguous and external to the first volume of revolution. This peripheral portion cooperates inside the second volume of revolution with regulating means arranged to cause the braking of the wheel set and to return the pivoting speed to the reference speed, and to dissipate any excess energy. This mechanism thus describes a system for regulation to an operating or reference speed, via a device which reduces speed/torque dependency.
EP Patent 2891930 in the name of THE SWATCH GROUP RESEARCH & DEVELOPMENT LTD describes a device for regulating the relative angular velocity between a magnetic structure and a resonator which are magnetically coupled to define together an oscillator, in particular with a magnetic escapement. The magnetic structure includes at least one annular path formed of a magnetic material of which one physical parameter is correlated to the magnetic potential energy of the oscillator, the magnetic material being arranged on the annular path so that the physical parameter varies angularly in a periodic manner. The annular path includes, in each angular period, an area of accumulation of magnetic potential energy in the oscillator, adjacent to an impulse area. The magnetic material in each accumulation area is arranged so that the physical parameter of the magnetic material gradually increases angularly or gradually decreases angularly so that the magnetic potential energy of the oscillator increases angularly during a rotation of the magnetic structure relative to the resonator.
Dissipation in an escapement is generally minimised, since this defines the efficiency of the oscillator. However, by controlling the instants of appearance and of disappearance of friction related to a particular function, it is possible to preserve the efficiency of the mechanism concerned, while utilising the dissipation for functional or acoustic or even aesthetic applications.
In an escapement mechanism in which the escape wheel is conventionally driven by a barrel, the torque communicated by the barrel varies as it unwinds, the energy transmitted to the escapement is lower after several hours of operation than just after winding. Likewise, there is a variation in torque, and thus in energy, dependant on the gear trains, due especially to profile differences, and tribological phenomena. For an escapement to achieve constant force, it is advantageous for energy to be rendered superfluous after a certain torque, by dimensioning a suitable mechanism; this is the operating mode of a magnetic escapement. This energy rendered superfluous by the operation of the escapement must, however, be dissipated in one manner or another. More generally, in any conventional escapement, the kinematic energy of the pallet-lever after the impulse, before stopping against the solid banking, is superfluous energy.
The present invention endeavours first to act on accelerations due to the actual working of the mechanism, through an arrangement that also has the advantage of limiting the undesirable effect of accelerations imparted by an external factor.
Application of the principle of controlled dissipation to an escape wheel makes it possible to obtain a wheel that slows down gradually after the impulse function. The advantages that result therefrom are:
a more continuous operation,
less repercussion of the drop impact in the other gear trains,
a drop impact that is less audible to the wearer,
a drop impact that is spaced further apart from the impacts of the other functions during measurement (ease of measurement),
less rebound of the escape wheel against the pallet-stones,
less wear.
Currently, no system of controlled dissipation is used in an escapement mechanism. Dissipation through untimely accelerations, shocks and friction on constant force escapements, which depend on tribology, is not controlled.
The magnetic regulator is the only system in which excess energy is dissipated through eddy currents, but its action depends on the torque applied and not on the positioning of the moving parts.
It is possible to envisage the use of other means of forced dissipation, for example through mechanical friction, through shocks, or through the use of an idler wheel friction driven by the gear train and which continues to rotate for a short time in the event of rebound due to its inertia, thereby increasing friction in the event of rebound. Once again, mechanical energy dissipations are difficult to control and to dimension.
Any escapement mechanism requiring dissipation of excess energy, and particularly any magnetic type escapement, benefits from incorporating a system wherein the amplitude and peak of dissipation are controlled. In a magnetic escapement, for example, this excess energy causes visible rebounds of the escape wheel against its magnetic banking, which risk causing variations in rate in the event of micro-shocks, and are less convenient from the aesthetic point of view.
The invention proposes to control energy dissipation in a timepiece mechanism including at least one stator and at least one rotor arranged to cooperate with each other, as a function of the respective angular positions between the stator and rotor, or the stators and rotors as appropriate.
The present invention proposes, more particularly but in a non-limiting manner, to use controlled dissipation through eddy currents, to dissipate all the excess energy in a single rebound.
To this end, the invention concerns a regulating mechanism according to claim 1.
The invention also concerns an escapement mechanism including such a regulating mechanism.
The invention also concerns a timepiece movement including at least one such regulating mechanism.
The invention also concerns a watch including such a movement, and/or at least one such regulating mechanism.
The system according to the invention may equally be placed in a conventional escapement, to take advantage of purely viscous friction, which dissipates much more energy before the drop, where the velocity of the wheel is maximum, and diminishes the intensity of the drop impact. The rebounds of the wheel against the pallet-stone, which are sometimes very considerable, can thus be minimised, and the risk of breakage of the wheel teeth can be avoided, in particular when it is made of silicon or another similar micromachinable material, or the risk of plastic deformation.
The invention is advantageous for control of isochronism. Indeed, the rebounds of the wheel in an escapement limit the frequency, since the next vibration must occur at a time when rebounds are reduced in order to avoid impairing the function. By quickly damping this friction it is possible to have vibrations closer in time, and thus to achieve a higher oscillator frequency, which consequently produces better adjustment power.
Another application of the invention consists in a system for fine adjustment of the amplitude of a balance. Indeed, it is important, when calculating the dimensions of an oscillator, not to devise an operating amplitude that is too high, which risks causing problems of knocking during operation of movements. With an eddy current brake system according to the invention, in which penetration, and therefore dissipation, is adjustable by the watchmaker, it is possible to devise balances operating at high amplitude, with no risk of knocking, and with very low dispersion in production.
Other features and advantages of the invention will appear upon reading the following detailed description, with reference to the annexed drawings, in which:
The invention proposes to control energy dissipation in a timepiece mechanism including at least one stator and at least one rotor arranged to cooperate with each other, as a function of the respective angular positions between the stator and rotor, or the stators and rotors as appropriate.
The invention applies both to the usual case where at least one of the opposing components, conventionally the stator, is fixed, and to the case where the rotor is a mobile component or a wheel set belonging to a first mechanism, and the stator is another mobile component or wheel set belonging to a second mechanism.
To control these variations in the respective angular positions, a preferred implementation of the invention which is more precisely described here, but in a non-limiting manner, consists in utilising, in a timepiece mechanism dedicated to a particular function, the properties of eddy currents to dissipate, in a targeted manner, the energy that is unnecessary for the achievement of this particular function.
The invention also endeavours to allow the watchmaker to effect a fine adjustment of the impact (positioning) of the dissipating elements.
In particular variants, such a fine adjustment can also be controlled by the movement itself, as a function of the remaining power reserve, or of any other pertinent operating parameters.
Thus, the invention concerns a regulating mechanism 100 for dissipating energy superfluous to the achievement of the function of a timepiece mechanism 200 including a functional mobile component 300, more particularly a wheel set, and particularly capable of limiting the effect of accelerations due to the actual operation of mechanism 200, and the effect of untimely accelerations of external origin, notably shocks, on such a functional mobile component 300.
According to the invention, this regulating mechanism 100 is arranged to control a dissipation of energy if functional mobile component 300 races. Regulating mechanism 100 includes at least one rotor 10, which is kinematically connected to functional mobile component 300, or which is formed by functional mobile component 300 or is integral therewith.
This rotor 10 includes either a conductive rotor part 11 which is magnetically permeable, or a magnetized rotor part 12 which is magnetized.
Regulating mechanism 100 includes, in an annular area of magnetic interaction, in direct proximity to and opposite conductive rotor part 11, or respectively magnetized rotor part 12, at least one stator 20 arranged to cooperate with rotor 10.
Stator 20 then includes a magnetized stator part 21 which is magnetized, or respectively a magnetically permeable conductive stator part 22, depending on the arrangement of the rotor 10 with which it cooperates.
“Conductive material” means an electrical conductor, carrying electrical charges, such as copper, silver, or similar, according to the custom of the person skilled in the art.
In the annular area of magnetic interaction, at least rotor 10 or stator 20 includes at least one raised area 15, 25, in which rotor 10 or stator 20 is capable of moving into superposition respectively with stator 20, or rotor 10, in a magnetic interaction. And, in this same annular area, at least rotor 10 or stator 20 includes at least one hollow or recessed area 16, 26, in which rotor 10 or stator 20 cannot move into magnetic interaction with stator 20, or rotor 10 respectively. The dissipation of energy depends on the relative angular position of rotor 10 and stator 20, and can only occur when solid parts of rotor 10 and of stator 20 are facing each other in the annular area.
More particularly, regulating mechanism 100 is arranged to control a dissipation of energy through eddy currents if functional mobile component 300 races, in the annular area.
More particularly still, at least rotor 10 or stator 20 includes an alternation of such raised areas 15, 25, in which rotor 10 or stator 20 is capable of moving into superposition with stator 20, or rotor 10 respectively, in an interaction generating eddy currents. Further, at least rotor 10 or stator 20 includes an alternation of such hollow areas 16, 26, in which rotor 10 or stator 20 is not capable of moving into superposition with stator 20 or rotor 10 respectively, and where the interaction between rotor 10 and stator 20 cannot generate eddy currents.
The velocity of rotor 10 depends on the mechanism 200 to be regulated. However, the object of the invention is not to regulate the velocity of this rotor, but to dissipate energy when an abnormal acceleration is imparted to mechanism 200.
The invention is described here more particularly for application to an escapement mechanism. This application is not limiting.
In this application to an escapement mechanism 200, the velocity of rotor 10 depends on the velocity of an escape wheel 3 comprised in escapement mechanism 200. Conductive rotor part 11, or magnetized rotor part 12, may form all or part of the actual escape wheel 3.
The first variant of
It is possible to place such a device on at least one additional wheel set 7, connected to the escapement by a set of gear trains, as seen in
It is naturally possible to add several targeted dissipation systems, to several different wheel sets connected by a gear train. The advantage is to obtain higher dissipation and an averaging out of the defects of the various systems.
It is advantageous to be able to adjust the maximum intensity of the eddy currents, by adjusting the eddy current dissipation by a modification—manual or controlled by a mechanism—of the penetration or of the distance between the conductive and magnetized parts: conductive rotor part 11 cooperating with a magnetized stator part 21, or magnetized rotor part 12 cooperating with a conductive stator part 22.
An example embodiment according to the
Magnetic escapement mechanisms are described in The Swatch Group Research and Development Ltd Patent Applications CH02140/13, CH01416/14 and CH01129/15, Nivarox-FAR SA Patent Applications CH01444/14 and CH 01445/14, and ETA Manufacture Horlogère Suisse Patent Applications CH01290/14 and CH01127/15, which are incorporated herein by reference.
A particular application concerns the fine adjustment of the amplitude of a balance wheel, through adjustment of the eddy current dissipation by a manual or controlled modification of the penetration or of the distance between the conductive part and the magnetized part, in the annular area, with such a device.
More particularly, regulating mechanism 100 includes second means 60 for adjustment of the angular position of at least one of rotors 10 with respect to the others: a fine adjustment is achieved by turning either upper wheel 13 or lower wheel 14, formed here by plates of magnets, with respect to the other, with the aid of a control pinion 61, in order to de-index the magnets and to diminish the magnetic flux variation caused by a rotation of the wheel set. The rare earth magnets may or may not have an alternate direction of magnetization.
Such a mechanism can also be achieved using a conductive rotor part 11 cooperating with a magnetized stator part 21, or a magnetized rotor part 12 cooperating with a conductive stator part 22, which are arranged to move closer to each other axially, instead of varying penetration.
Modulation of the amplitude of dissipated energy may also be obtained through variation of the thickness of the conductive part or of the magnetized part. It is therefore possible to achieve such a mechanism, in particular, using a conductive rotor part 11 cooperating with a magnetized stator part 21, or a magnetized rotor part 12 cooperating with a conductive stator part 22, whose thickness varies, instead of varying penetration.
As regards variation of dissipation as a function of variation of thickness, dependence is virtually linear: by imparting a variation of thickness of 50%, there is obtained, in the aforecited example based on
The invention more particularly concerns a timepiece escapement mechanism 200, including at least one escape wheel 300, and escapement mechanism 200 includes such a regulating mechanism 100, arranged to limit the effect of accelerations, particularly shocks, on the escape wheel 300.
The invention also concerns a timepiece movement 400 including at least one escapement mechanism 200 of this type.
The invention also concerns a watch 500 including at least one such timepiece movement 400, and/or at least one such regulating mechanism 100.
For example, watch 500 includes another mechanism 600, independent of movement 400, controlled by such a regulating mechanism 100.
The invention is also applicable to other mobile devices, such as devices for automobile, naval or air equipment, time-delay devices for munitions, or similar.
In order to protect the exterior of the watch, in particular the wearer and sensitive devices, against the magnetic fields of such a system, and to increase the efficiency of the system, it is possible and advantageous to add a ferromagnetic shield, not illustrated in the Figures.
The generation of eddy currents is connected to a field variation, the first being precisely generated by the second (local variation at best). In the variant of
It will be noted that the invention differs from the aforecited teaching of CH Patent 704457 in the name of MONTRES BREGUET SA, since the invention does not adapt to the imposed torque, but causes a purely viscous braking that depends on the position of the magnetic part with respect to the conductive part, and thus on the function in progress. However, a higher torque will always produce a higher operating speed. Further, no actual speed regulation occurs, it is rather a case of dissipating energy that is not actually used by the mechanism upstream or downstream.
The invention also differs considerably from the teachings of the aforecited EP Patent 2891930 in the name of THE SWATCH GROUP RESEARCH & DEVELOPMENT LTD, in which the principle of interaction is different from that of the invention (magnetic force with no induction effect) and the object of the device is to obtain a constant frequency via the magnetic excitation of an oscillator. The magnetic forces are used to transmit an impulse or a stop to the oscillating part.
A particularly advantageous embodiment of the invention is that wherein the magnetized part and the conductive part have a relief profile. No matter how it is desired to obtain a braking torque that varies during the function, it can be obtained by means of a relief profile of the two components. The manner in which this relief is achieved, for example radial or axial geometric variation of one part and/or the other, lack of magnetic or conductive material at certain angles, or other, may then vary according to the embodiment.
Although a particular use of the invention for an escapement is especially advantageous, the system can be used on other wheel sets, for example only for dissipating energy between take-offs of torque due to a striking work or similar.
In short, the invention provides numerous advantages:
the elimination of rebounds, without affecting efficiency,
improved safety features, with improved operation in the event of micro-shocks,
more continuous operation of the gear trains,
fine adjustment of the amplitude of the oscillators, and notably allowing high amplitude without any risk of knocking,
drop impacts that are less audible yet more easily identifiable, and spaced further apart from the impacts of the other functions, which provides a new ease of measurement,
less wear, and
less frequency limitation.
Number | Date | Country | Kind |
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15201020.3 | Dec 2015 | EP | regional |