WO2019156552A1

WO2019156552A1 - Mechanical watch oscillator

Info

Publication number: WO2019156552A1
Application number: PCT/NL2019/050044
Authority: WO
Inventors: Wout Johannes Benjamin Ypma; Sybren Lennard Weeke
Original assignee: Flexous Mechanisms Ip B.V.
Priority date: 2018-02-06
Filing date: 2019-01-28
Publication date: 2019-08-15
Also published as: NL2020384B1; EP3750009A1; CN111771169A; CN111771169B; JP7213270B2; JP2021514476A

Abstract

Mechanical watch oscillator (100) comprising a platform (2), which platform (2) is provided with at least two vibratory masses (11, 12, 13) that are suspended on the platform (2), wherein each of the masses (11, 12, 13) is individually suspended on the platform (2) with at least one flexural member (21, 31; 22, 32; 23, 33), and wherein at least two vibratory masses (11, 12, 13) are interconnected by two parallel flexural beams (41 - 48) providing a direct torsion stiff connection between these at least two vibratory masses (11, 12, 13), and wherein a first mass (11) of the at least two masses (11, 12, 13) and the at least one flexural member (21 or 31) that provides a connection of the first mass (11) to the platform (2) is mirror symmetric with reference to a second mass (12) of the at least two masses (11, 12, 13) and the at least one flexural member (22 or 32) that provides a connection of the second mass (12) to the platform (2), wherein said mirror symmetry applies to a line of symmetry (A) through a center of the oscillator (100).

Description

Mechanical watch oscillator

The invention relates to a mechanical watch oscilla- tor .

Mechanical watch oscillators are known from WO2016/062889, WO2017/068538 , EP 2 273 323, EP 3 035 126, and EP 3 035 127, just to name a few.

WO2016/062889 discloses a mechanical watch movement regulating member comprising an escape wheel and a vibrating oscillator provided with at least two vibrating arms and pal lets firmly joined to said vibrating arms and comprising two members arranged to interact directly with the teeth of the escape wheel for maintaining the periodic alternations of the vibrating oscillator and causing the escape wheel to advance with each oscillation alternation. The vibrating masses in WO2016/062889 are not geometrically interconnected, which means that the oscillation amplitude and phase of those masses do not remain in phase during shocks, accelerations and/or orientation change, which in turn results in timekeeping inac curacy .

WO 2017/068538 discloses an oscillator for adjusting a mechanical timepiece movement, the oscillator comprising an escape wheel and a resonator that forms the time basis of the oscillator, the resonator including a mass element which is kept in oscillation by at least two vibrating elements; said mass element including at least one anchor portion which is rigidly connected to the mass element and configured to di rectly engage with the escape wheel in order to maintain os cillations of the resonator and to allow the escape wheel to move with each alternation of the oscillation. A disadvantage of the device of WO 2017/068538 is that if embodied with two flexures or elastic suspensions to the ground, it will have high susceptibility to out-of-plane shocks (i.e. shocks per pendicular to the working plane) . The center-of-mass of such a device with two flexures cannot be stationary. If embodied with more than two flexures, it is not possible for the device to undergo large deformations while keeping isochronism (i.e. timekeeping precision) . EP 2 273 323 discloses an oscillator comprising a fastening portion designed to be fastened to a frame of a timepiece, and a plurality of elastic systems connecting a felloe and the fastening portion to each other, wherein each elastic system comprises two return organs arranged in series and connected to each other by the frame wherein at least some of the elastic systems are suspended and free with reference to the frame. The oscillator of EP 2 273 323 has flexures in series with multiple degrees of freedom and therefore will have low resistance against shocks. Moreover, this known os cillator is manufactured with features distributed in multiple planes, increasing fabrication and assembly difficulties.

EP 3 035 126 discloses a timepiece resonator with an oscillating weight, wherein the resonator can be mounted on a timepiece, wherein the weight is suspended by crossed resili ent strips that extend at a distance of each other in parallel planes, wherein the resonator is of the tuning fork type with at least two weights oscillating in symmetry. This known de vice with two base flexures will have low resistance against shocks out-of-plane (i.e. shocks perpendicular to the working plane) . Moreover, this oscillator is manufactured with fea tures distributed in multiple planes, increasing fabrication and assembly difficulties.

EP 3 035 127 discloses a timepiece oscillator with a resonator of the tuning fork type, which includes at least two mobile oscillating parts that are secured to a connection ele ment comprised in the oscillator with flexible elements, wherein the respective mobile parts oscillate about a virtual pivot axis and wherein the center of the mass of the mobile parts coincides in its rest position with the virtual pivot axis, and wherein the flexible elements of at least one mobile part are formed of intersecting resilient strips. In this known device, the vibrating masses are not geometrically in terconnected, which means that the oscillation of those masses do not remain in phase during shocks, accelerations and/or orientation change, ultimately

causing timekeeping inaccuracy. Moreover, this known oscilla tor is manufactured with features disputed in multiple planes, increasing fabrication and assembly difficulties. It is an object of the invention to provide a me chanical watch oscillator with high resistivity for gravita tional varying influences due to different orientations of the oscillato .

It is another object of the invention to provide a mechanical watch oscillator with high shock resistance.

It is still another object of the invention to pro vide a mechanical watch oscillator with possible smaller di mensions than the prior art oscillators.

These and other objects of the invention which may become apparent from the following disclosure, are provided with a mechanical watch oscillator according to one or more of the appended claims .

In a first aspect of the invention the mechanical watch oscillator comprises a platform, which platform is pro vided with at least two vibratory masses that are suspended on the platform, wherein each of the masses is individually sus pended on the platform with at least one flexural member, and wherein at least two vibratory masses are interconnected by at least two parallel flexural beams providing a direct torsion stiff connection between these at least two vibratory masses, and wherein a first mass of the at least two masses and the at least one flexural member that provides a connection of the first mass to the platform is substantially mirror symmetric with reference to a second mass of the at least two masses and the at least one flexural member that provides a connection of the second mass to the platform, and wherein said mirror sym metry applies to a line of symmetry through a center of the oscillator. The word 'substantially' in the previous sentence expresses that intended and unintended inaccuracies regarding the weight or shape of the masses and the orientation of the flexural members that provide a connection of the masses with the platform are comprised within the scope of the invention. From an engineering point of view inaccuracies up to a maximum of 10% of the nominal values are allowable, without departing from the scope of the invention. With respect to the orienta tion of the flexural members orientation of differences of 10% of the 360° full circle are allowable without departing from the scope of the invention. Of course best results are achieved when the mirror symmetry is perfect, and when the masses are of exactly equal weight and shape.

The previously mentioned features in combination pro vide that the mechanical watch oscillator of the invention is highly resistant against gravitational influences that may oc cur in connection with different orientations of the oscilla tor .

In a second aspect of the invention which is applica ble standing on its own or in combination with the features according to the above discussed first aspect of the inven tion, or in combination with any of the following features to be discussed hereinafter, the mechanical watch oscillator com prises a platform which is provided with at least two vibrato ry masses that are suspended on the platform, wherein each of the masses is individually suspended on the platform with at least one flexural member, and wherein at least two vibratory masses are interconnected by at least two parallel flexural beams providing a direct torsion stiff connection between these at least two vibratory masses, and wherein the two par allel flexural beams are rotationally symmetric only with ref erence to a full circle or a half-circle rotation of the os cillator. Wikipedia defines rotational symmetry, also known as radial symmetry in biology, as the property a shape has that it looks the same after some rotation by a partial turn. An object's degree of rotational symmetry is the number of dis tinct orientations in which it looks the same. In this inven tion the feature "rotationally symmetric only with reference to a full circle or a half-circle rotation of the oscillator" thus means that it takes a full 360° rotation or a 180° rota tion of the oscillator until it has again the same shape or look as when it is turned over an angle of 0°, that is when it is not yet turned. The said combined features provide that the oscillator can be manufactured smaller and cheaper, or alter natively that it provides room for other features such as for instance an escape wheel within the circumference provided by the vibratory masses of the oscillator. Because of the possi ble size reduction the oscillator can also be more energy ef ficient or less energy consuming and provide better endurance, with better shock resistance due to reduced mass. The following features can be applied with the me chanical oscillator of the invention according to the above discussed first aspect, or in combination with the mechanical oscillator of the invention according to the above discussed second aspect. All features as discussed herein can also be applied cumulative.

Preferably the at least two masses are mutually con nected by two sets of two parallel flexural beams, which sets are placed in series and are preferably provided with equal length. Each individual set of flexural beams allows for a relative translation between the two ends of each set of flex ural beams. Because the two sets of flexural beams are put in series, the two ends of the sets of flexural beams can move in two translational directions, spanning a surface, but rotation between the two ends of the sets of flexural beams is avoided. By mounting these two sets of parallel flexural beams between the two masses, an equal amplitude of vibration with zero phase shift is geometrically guarantied between the two mass es, which is beneficial for maintaining stability of the cen ter of mass of the oscillator, and to promote the oscillator' s shock resistance.

In a preferred embodiment at least one of the masses is individually suspended on the platform with two flexural members. This also increases the oscillator's shock re

sistance. Preferably all masses of the oscillator are individ ually suspended on the platform with two flexural members to further promote the oscillator's shock resistance.

In embodiments wherein the number of masses counts n, it is preferred that all masses are connected to each other with at least n-1 sets of interconnections between the masses, wherein each set of interconnections comprises at least two parallel flexures. This fully constrains rotation of the mass es with respect to each other.

At least some of the objectives of the invention are further promoted in an embodiment wherein the first mass of the at least two masses and the two flexural members that pro vide a connection of the first mass to the platform, and the second mass of the at least two masses and the two flexural members that provide a connection of the second mass to the platform are mirror symmetric according to two lines of sym metry that are orthogonal with reference to each other.

Preferably the at least one flexural member by which each of the masses is individually suspended on the platform, and the at least two parallel flexural beams that provide a direct torsion stiff connection between the at least two vi bratory masses are embodied with rigid sections. This feature increases the shock levels at which buckling occurs of the flexural members and flexural beams.

Shock resistance is further promoted by arranging that the at least two vibratory masses are embodied with first mechanical stops that are arranged to limit the displacement of the vibratory masses relative to the platform.

In this connection it is further beneficial that the at least two vibratory masses are embodied with second mechan ical stops that are arranged to limit the displacement of the vibratory masses relative to each other.

Mechanical blocking of relative motion as mentioned in the two previous paragraphs reduces stress in the flexural members and beams and reduces the risk of fracture.

The invention will hereinafter be further elucidated with reference to the drawing of several exemplary embodiments of a timepiece oscillator according to the invention that is not limiting as to the appended claims.

In the drawing:

-figures 1A and IB shows a first embodiment of a timepiece oscillator according to the invention in plane-view and isometric view, respectively;

-figures 2A and 2B shows a second embodiment of a timepiece oscillator according to the invention in plane-view and isometric view, respectively;

-figures 3A and 3B shows a third embodiment of a timepiece oscillator according to the invention in plane-view and isometric view, respectively;

- figure 4 shows a fourth embodiment of a timepiece oscillator according to the invention in plane-view; and

- figure 5 shows a fifth embodiment of a timepiece oscillator according to the invention in plane-view. Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

Turning first to figures 1A, IB, 2A and 2B it shows two different embodiments wherein the oscillator 100 has two masses 11, 12 that are suspended elastically to a platform 2 with thin flexible elements 21, 31 and 22, 32.

With reference to both embodiments of figures 1A, IB, 2A and 2B the platform 2 of the oscillator 100 is provided with screw holes 61, 62 with which the oscillator 100 is con nectable to the remainder of a timepiece.

When the masses 11, 12 are vibrating extensions 51,

52 of these masses 11, 12 alternatively release and block an escape wheel 53, allowing the wheel to rotate in steps. Oscil lator 100 is held in oscillatory motion by energy input from the escape wheel 53.

The difference between the embodiments shown in fig ures 1A, IB, and figures 2A and 2B is that in the embodiment of figures 1A and IB the platform 2 is placed in the center of the oscillator 100, whereas in the embodiment of figures 2A and 2B the platform 2 is placed in the periphery of the oscil lator 100.

It is remarked that although each mass 11, 12 is shown to be individually connected with the platform 2 using two flexible elements 21, 31 and 22, 32, respectively, which signifies the most preferred embodiment that provides optimal shock resistance to the oscillator 100, it suffices within the scope of the invention that each mass 11, 12 is individually connected to the platform 2 with a single flexible element. As an example: for mass 11 it would suffice to apply only flexi ble element 21 or only flexible element 31, and with reference to mass 12 it would suffice to apply only flexible element 22 or only flexible element 32.

According to a first aspect of the invention it is however essential that a first mass 11 of the at least two masses and the at least one flexural member 21, 31 that pro vides a connection of the first mass 11 to the platform 2 is mirror symmetric with reference to a second mass 12 of the at least two masses and the at least one flexural member 22, 32 that provides a connection of the second mass 12 to the plat- form 2, wherein said mirror symmetry applies in relation to a line of symmetry A through a center of the oscillator 100.

This provides high resistance against gravitational influences on for instance the oscillating frequency due to orientation variations of the oscillator 100 of the invention.

If the embodiments as shown in figures 1A, IB, and figures 2A and 2B are provided with masses 11, 12, that each are individually connected with the platform 2 using two flex ible elements 21, 31 and 22, 32 respectively, it is preferred that the first mass 11 of the at least two masses and the two flexural members 21, 31 that provide a connection of the first mass 11 to the platform 2, and the second mass 12 of the at least two masses and the two flexural members 22, 32 that pro vide a connection of the second mass 12 to the platform 2 are mirror symmetric according to two lines of symmetry A, B that are orthogonal with reference to each other. This further im proves the insensitivity of the oscillator 100 for gravita tional influences due to different orientations of the oscil lator 100 of the invention.

It is further shown that in both embodiments of fig ures 1A, IB, and figures 2A and 2B the two masses 11, 12, which represent all masses in these embodiments, are prefera bly mutually connected by two sets of two parallel flexural beams 41, 42, and 43, 44 respectively, with equal length. Each individual set of flexural beams 41, 42 and flexural beams 43, 44 allows only for a relative translation between the two ends of each set of flexural beams. Because the two sets of flexur al beams are put in series, the two ends of the sets of flex ural beams can move in two translational directions, spanning a surface, but rotation between the two ends of the sets of flexural beams is avoided.

By mounting these sets of parallel flexural beams 41, 42, and 43, 44 between the two masses 11, 12, an equal ampli tude of vibration with zero phase shift is geometrically guar antied between the two masses 11, 12, which is beneficial for maintaining stability of the center of mass of the oscillator 100, and to promote the oscillator's shock resistance.

According to a second aspect of the invention the parallel flexural beams 41 - 44 in the embodiments of figures 1A, IB, and figures 2A and 2B are rotationally symmetric only with reference to a full circle or a half-circle rotation of the oscillator 100, thus providing room for the escape wheel 53 and the vibrating extensions 51, 52. The said room could of course also be used for other features as the need arises.

A third embodiment of the oscillator 100 of the in vention is shown in figure 3A and 3B, wherein in comparison with the embodiment of figures 1A and IB the oscillator 100 of figures 3A and 3B is provided with an additional mass 13. The foregoing elucidation with reference to the masses 11 and 12 and their mirror symmetry in connection with the flexures con necting these masses 11, 12 to the platform 2 according to the first aspect of the invention also applies to this embodiment of figures 3A and 3B. To be precise: also in figure 3A and 3B it is shown that the first mass 11 and the at least one flex ural member 21 or 31 that provides a connection of the first mass 11 to the platform 2 is mirror symmetric with reference to a second mass 12 and the at least one flexural member 22 or 32 that provides a connection of the second mass 12 to the platform 2, wherein said mirror symmetry applies to the axial line of symmetry A through the center of the oscillator 100. Also the second aspect of the invention concerning the paral lel flexural beams 41 - 48 being rotationally asymmetric and symmetric only with reference to a full circle rotation of the oscillator 100 applies in this embodiment, thus again provid ing room for -in this embodiment- the escape wheel 53 and the vibrating extensions 51, 52.

Like the third embodiment shown in figures 3A and 3B, the fourth embodiment shown in figure 4 is provided with a first mass 11, a second mass 12 and an additional mass 13. The difference of this fourth embodiment in comparison with the previously discussed embodiments is that it shows another pos sibility of connecting the masses to each other, wherein the two parallel flexural beams 41, 42 connect the two vibrating masses 11 and 13, and the two parallel flexural beams 47, 48 connect the two vibrating masses 12, 13. Further according to the first aspect of the invention in this embodiment the first mass 11 and the flexure 31 that provides a connection of the first mass 11 to the platform 2 is substantially mirror sym- metric with reference to the second mass 12 and the flexural member 22 that provides a connection of the second mass 12 to the platform 2, wherein said mirror symmetry applies to a line of symmetry A through a center of the oscillator 100. Also ac cording to the second aspect of the invention the parallel flexural beams 41 - 48 in the embodiment of figures 3A, 3B are embodied as rotationally symmetric only with reference to a full circle or a half-circle rotation of the oscillator 100.

Finally a fifth embodiment is shown in figure 5 with enhanced in-plane shock robustness, wherein the at least one flexural member 21, 31; 22, 32 by which each of the masses 11, 12 is individually suspended on the platform 2, and the at least two parallel flexural beams 41 - 44 that provide a di rect torsion stiff connection between the at least two vibra tory masses 11, 12, are embodied with rigid sections 21a, 31a; 22a, 32a; 41a - 44a. The rigid sections increase the shock level at which the flexural members and flexural beams buckle.

It further shows that the at least two vibratory masses 11, 12 are embodied with first mechanical stops 11a,

12a that are arranged to limit the displacement of the vibra tory masses 11, 12 relative to the platform 2, and that the at least two vibratory masses 11, 12 are embodied with second me chanical stops lib, 12b that are arranged to limit the dis placement of the vibratory masses 11, 12 relative to each oth er. Mechanical blocking of the said relative motions reduces stresses in the flexural members and beams and decreases the risk of their fracture. Although the invention has been dis cussed in the foregoing with reference to several exemplary embodiments of the oscillator of the invention, the invention is not restricted to these particular embodiments which can be further varied in many ways without departing from the inven tion. The discussed exemplary embodiments shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiments are merely intended to explain the wording of the appended claims without intent to limit the claims to these exemplary embodiments. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using these exemplary embodiments.

Claims

1. Mechanical watch oscillator (100) comprising a platform (2), which platform (2) is provided with at least two vibratory masses (11, 12, 13) that are suspended on the plat form (2), wherein each of the masses (11, 12, 13) is individu ally suspended on the platform (2) with at least one flexural member (21, 31; 22, 32; 23, 33), and wherein at least two vi bratory masses (11, 12, 13) are interconnected by at least two parallel flexural beams (41 - 48) providing a direct torsion stiff connection between these at least two vibratory masses (11, 12, 13), and wherein a first mass (11) of the at least two masses (11, 12, 13) and the at least one flexural member (21 or 31) that provides a connection of the first mass (11) to the platform (2) is substantially mirror symmetric with reference to a second mass (12) of the at least two masses (11, 12, 13) and the at least one flexural member (22 or 32) that provides a connection of the second mass (12) to the platform (2), wherein said mirror symmetry applies to a line of symmetry (A) through a center of the oscillator (100) .

2. Mechanical watch oscillator (100) comprising a platform (2), which platform (2) is provided with at least two vibratory masses (11, 12, 13) that are suspended on the plat form (2), wherein each of the masses (11, 12, 13) is individu ally suspended on the platform (2) with at least one flexural member (21, 31; 22, 32; 23, 33), and wherein at least two vi bratory masses (11, 12, 13) are interconnected by at least two parallel flexural beams (41 - 48) providing a direct torsion stiff connection between these at least two vibratory masses (11, 12, 13), and wherein the two parallel flexural beams (41 - 48) are rotationally symmetric only with reference to a full circle or a half-circle rotation of the oscillator (100) .

3. Mechanical watch oscillator (100) according to claim 1, wherein the two parallel flexural beams (41 - 48) are rotationally symmetric only with reference to a full circle or a half-circle rotation of the oscillator (100) .

4. Mechanical watch oscillator (100) according to any one of claims 1 - 3, wherein the at least two masses (11, 12) are mutually connected by two sets of two parallel flexural beams (41 - 48), which sets are placed in series and are pref erably provided with equal length.

5. Mechanical watch oscillator (100) according to any one of claims 1 - 4, wherein at least one of the masses (11, 12, 13) is individually suspended on the platform (2) with two flexural members (21, 31; 22, 32; 23, 33) .

6. Mechanical watch oscillator (100) according to any one of claims 1 - 5, wherein all masses (11, 12, 13) of the oscillator (100) are individually suspended on the platform (2) with two flexural members (21, 31; 22, 32; 23, 33) .

7. Mechanical watch oscillator (100) according to any one of claims 1 - 6, wherein if the number of masses counts n, all masses (11, 12, 13) are connected to each other with at least n-1 sets of interconnections between the masses (11, 12, 13) , wherein each set of interconnections comprises at least two parallel flexural beams (41 - 48) .

8. Mechanical watch oscillator (100) according to any one of claims 3 - 7, wherein the first mass (11) of the at least two masses (11, 12, 13) and the two flexural members (21, 31) that provide a connection of the first mass (11) to the platform (2), and the second mass (12) of the at least two masses (11, 12, 13) and the two flexural members (22, 32) that provide a connection of the second mass (12) to the platform (2) are mirror symmetric according to two lines of symmetry (A, B) that are orthogonal with reference to each other.

9. Mechanical watch oscillator (100) according to any one of claims 1 - 8, wherein the at least one flexural member (21, 31; 22, 32) by which each of the masses (11, 12, 13) is individually suspended on the platform (2), and the two paral lel flexural beams (41 - 44) that provide a direct torsion stiff connection between the at least two vibratory masses (11, 12) are embodied with rigid sections (21a, 31a; 22a, 32a; 41a - 44a) .

10. Mechanical watch oscillator (100) according to any one of claims 1 - 9, wherein the at least two vibratory masses (11, 12) are embodied with first mechanical stops (11a, 12a) that are arranged to limit the displacement of the vibra tory masses (11, 12) relative to the platform (2) .

11. Mechanical watch oscillator (100) according to any one of claims 1 - 10, wherein the at least two vibratory masses (11, 12) are embodied with second mechanical stops (lib, 12b) that are arranged to limit the displacement of the vibratory masses (11, 12) relative to each other.