Classifications

• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/32—Component parts or constructional details, e.g. collet, stud, virole or piton
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/20—Compensation of mechanisms for stabilising frequency
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/04—Oscillators acting by spring tension
  • G04B17/045—Oscillators acting by spring tension with oscillating blade springs
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/04—Oscillators acting by spring tension
  • G04B17/06—Oscillators with hairsprings, e.g. balance
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/04—Oscillators acting by spring tension
  • G04B17/06—Oscillators with hairsprings, e.g. balance
  • G04B17/063—Balance construction
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/20—Compensation of mechanisms for stabilising frequency
  • G04B17/28—Compensation of mechanisms for stabilising frequency for the effect of imbalance of the weights, e.g. tourbillon

Definitions

• the present invention relates to a horological oscillator which can serve as a time base in a mechanical horological movement.
• the present invention relates to a flexible pivot horological oscillator, that is to say a horological oscillator without a physical axis of rotation rotating in bearings.
• a flexible pivot horological oscillator that is to say a horological oscillator without a physical axis of rotation rotating in bearings.
• Such an oscillator pivots around a virtual axis of rotation thanks to an arrangement of elastic parts.
• pivots with separate cross blades pivots with non-separated cross blades or pivots with offset center of rotation
• RCC Remote Center Compliance
• the blades In a separate cross-leaf pivot, the blades extend in two parallel planes to intersect without contact. In an unseparated cross-leaf pivot, they extend in the same plane to physically intersect.
• the offset center of rotation pivot it includes two blades that do not intersect but extend along axes that intersect. In all cases, the intersection of the blades or their axes defines the virtual axis of rotation.
• a watch oscillator with a flexible pivot is insensitive to gravity or in other words that its frequency varies as little as possible depending on its orientation with respect to the force of gravity.
• patent application EP 291 1012 proposes to arrange the elastic blades such that their point of intersection is located at 7/8 th of their length in accordance with the theory developed by WH Wittrick in the article “The properties of crossed flexure pivots and the influence of the point at which the strips cross”, The Aeronautical Quarterly, vol. II, February 1951, the theoretical value being in fact 1/2 + 5/6, or about 87.3% of the length.
• This The position of the crossing point is in fact that which minimizes the parasitic displacements of the virtual axis of rotation and therefore the dependence of the frequency of the oscillator with respect to gravity.
• the present invention aims to provide a new way of improving the operating precision of a flexible pivot horological oscillator, which may or may not be combined with that consisting in choosing a particular position for the point of intersection of the blades or of their axes. .
• a method for adjusting a watch oscillator comprising a balance, a support and a flexible pivot connecting the balance to the support and guiding the balance in rotation relative to the support around a virtual axis of rotation, the flexible pivot having, in orthogonal projection in a plane perpendicular to the virtual axis of rotation, an axis of symmetry which is also an axis of symmetry for the points of junction of the flexible pivot to the balance, characterized in that one adjusts the unbalance of the balance so that, in orthogonal projection in said plane, the center of mass of the balance is substantially on the axis of symmetry and at a position distinct from that of the virtual axis of rotation, said position being chosen so as to decreasing, and preferably minimizing, the dependence of the oscillation frequency on the orientation of gravity for a predetermined oscillation amplitude.
• the present invention further provides a clock oscillator adjustable by the method as defined above.
• the Applicant has discovered that a correlation exists between the amplitude of oscillation, the position of the center of mass of the balance and the sensitivity of the oscillator to gravity. From a given amplitude of oscillation, we can find a position of the center of mass of the balance along the axis of symmetry of the flexible pivot which minimizes the difference in rate between the different vertical positions of the oscillator by relative to the force of gravity. It is thus possible, by the adjustment according to the invention, to obtain a watch oscillator with performance at least equivalent to that of a Wittrick type oscillator and operating at a different amplitude, more suited to the characteristics of the movement for which it is intended. to be part.
• FIGS. 1 and 2 are respectively a top plan view and a perspective view of a flexible pivot horological oscillator according to a particular embodiment of the invention
• FIGS. 3 to 5 are diagrams showing the operation of flexible pivot oscillators as a function of the amplitude of oscillation and the orientation of the oscillator with respect to gravity;
• FIG. 6 is a diagram showing a relationship between the unbalance of the oscillator balance and the oscillation amplitude minimizing the deviation between the different vertical positions of the oscillator;
• FIGS. 7 and 8 are respectively a top plan view and a perspective view of a flexible pivot horological oscillator according to another embodiment of the invention.
• FIGS. 1 and 2 show a watch oscillator with a flexible pivot according to a particular embodiment of the invention, intended to fulfill the function of a sprung balance in a mechanical watch movement, in particular a wristwatch or pocket watch movement.
• This oscillator designated by 1, comprises an oscillating body or balance 2, a support 3 and a flexible pivot 4.
• the support 3 is intended to be fixed to a fixed or mobile frame of the movement.
• the flexible pivot 4 is here in the form of two elastic strips 5, 6 extending in respective parallel planes P1, P2 and crossing without contact. Each of these blades 5, 6 is joined by one end 5a, 6a to the balance 2 and by its other end 5b, 6b to the support 3.
• the balance 2 is thus held to the support 3 only by the flexible pivot 4, which guides it in rotation relative to the support 3 around a virtual axis of rotation and resiliently returns it to a rest position, namely the position illustrated in Figures 1 and 2.
• the virtual axis of rotation extends perpendicularly to the planes P1, P2 and corresponds, in orthogonal projection in any one of these planes P1, P2 (cf. FIG. 1), to the point of intersection O between the plates 5, 6, more precisely to the point of intersection between the neutral fibers of these plates.
• the crossing point O is the center of a coordinate system (O, X, Y) whose Y axis is an axis of symmetry for the plates 5, 6, this axis of symmetry passing between the points 5a , 6a junction of the blades 5, 6 to the balance 2 and between the points 5b, 6b of junction of the blades 5, 6 to the support 3.
• the balance 2 is in the form of a ring surrounding the pivot flexible 4. It could alternatively be of the cut type.
• FIG. 3 is shown the rate of oscillator 1 as a function of its oscillation amplitude and its orientation with respect to the force of gravity for a point of intersection O of the blades 5, 6 located at 87.3% of their length, that is to say at the optimal position proposed by WH Wittrick.
• This position of the crossing point O is measured from the points 5a, 6a of junction of the blades 5, 6 to the balance 2 but can, as a variant, be measured from the points 5b, 6b of the junction of the blades 5, 6 to the support 3, the crossing point O can equally well be situated on the side of the support 3 or of the balance 2.
• the rate in seconds / day is plotted on the ordinate and the oscillation amplitude in degrees on the abscissa.
• the four curves C1 to C4 correspond respectively to four vertical positions of the oscillator spaced 90 ° apart. In these four vertical positions, respectively, the force of gravity is directed along the semi-axis (O, -Y), the semi-axis (O, X), the semi-axis (O, -X) and the semi-axis. axis (O, Y). Curves C2 and C3 are merged taking into account the symmetry of the oscillator with respect to the Y axis.
• the invention provides for unbalancing the balance 2 so that its center of mass M is distinct from the cross point O of the blades 5, 6 and therefore of the center of rotation of the balance 2, in orthogonal projection in any one of the planes P 1, P2.
• the oscillation amplitude is modified for which the rate difference between the various vertical positions of the oscillator is minimal.
• Figures 4 and 5 This is illustrated in Figures 4 and 5 which were obtained with the same parameters as for Figure 3 but with a center of mass M of the balance 2 located on the Y axis at a distance DU from point O equal to 30 pm (corresponding at an unbalance of 15 nN.m) for FIG. 4, and at a distance DU from point O equal to 50 ⁇ m (corresponding to an unbalance of 25 nN.m) for FIG. 5.
• the amplitude of oscillation at which the frequency is least dependent on the orientation of gravity is about 24 °.
• Figure 5 it is around 30 °.
• Figures 4 and 5 illustrate the effect of a displacement of the center of mass M on the semi-axis (O, Y).
• FIG. 6 shows the relationship between the oscillation amplitude giving the minimum operating difference between the four aforementioned vertical positions of oscillator 1 and the unbalance of balance 2. It can be seen that for each oscillation amplitude we can find an unbalance, more exactly a position of the center of mass M of the balance 2 on the Y axis, which corresponds to it.
• the distance DU between the center of mass M of the balance 2 and the crossing point O is preferably at least 1.4 ⁇ m, more preferably at least 2 ⁇ m, more preferably at least 5 ⁇ m, more preferably at least 10 ⁇ m, more preferably at least 20 ⁇ m, more preferably at least 40 ⁇ m.
• the unbalance, for its part, is preferably at least 0.7 nN.m, more preferably at least 1 nN.m, more preferably at least 2.5 nN.m, more preferably at least 5 nN.m, more preferably at least 10 nN.m, more preferably at least 20 nN.m, in absolute value.
• the unbalance of balance 2 is adjusted to minimize the rate difference between the positions vertical at this oscillation amplitude.
• the adjustment can be carried out by removing material from the balance 2, for example by milling or laser machining, or by adding material to the balance 2, for example by a deposition technique.
• the unbalance can be adjusted by means of an adjustment device carried by the balance 2.
• FIG. 1 and 2 An example of such an adjustment device is shown in Figures 1 and 2. It comprises a support 7 integral with the balance 2 and preferably monolithic with the latter. This support 7 extends radially from the internal face of the balance 2 facing the virtual axis of rotation. Two pins 8, 9 integral with the support 7 and preferably monolithic therewith are surrounded by, and serve as guides for, a frame 10 movable in translation relative to the support 7 along the Y axis. less of the pins 8, 9 has a larger diameter than the internal width of the frame 10 to elastically deform its two long sides and thus maintain it in position by elastic clamping. Applying sufficient force to the frame 10 in the direction of the Y axis moves the frame 10 to modify the unbalance of the balance 2.
• One or more recesses may be made on the balance 2 to compensate for the imbalance caused by the balance.
• support 7, the pins 8, 9 and the frame 10 so that, in a determined position of the frame 10, for example a position in which it abuts against one of the two pins 8, 9, the unbalance of the balance 2 is substantially zero.
• a displacement of the frame 10 then unbalances the balance 2 by moving its center of mass M along the Y axis from point O, allowing precise adjustment of the unbalance.
• the balance 2 can therefore also carry weights which will be used to adjust the moment of inertia, in a manner that is conventional in itself.
• the balance 2 could carry on its periphery one or more adjustment screws, for example one or two screws oriented along the Y axis, the adjustment being carried out by screwing more or minus these screws in the balance 2.
• FIGS. 7 and 8 show an oscillator 1 'according to another embodiment of the invention, in which the unbalance adjustment device is located in the center of the oscillator in order to modify the moment of inertia of the balance 2 as little as possible. and facilitate the adjustment of this moment of inertia by means of weights carried by the balance 2.
• the balance 2 here comprises a rim 2a and a diametral arm 2b.
• the diametral arm 2b is interrupted in its central part to allow the blades 5, 6 to pass through.
• the two segments of the diametral arm 2b could be connected by a concave connection 2c on which s 'would stop the blades 5, 6, the crossing point of which would then be closer to the balance 2 than to the support 3.
• the unbalance adjustment device is mounted on the diametral arm 2b. It includes a support 11 fixed on top of the diametral arm 2b and carrying a central stud 12 centered on the virtual axis of rotation of the balance 2.
• the unbalance adjustment device further comprises an adjustment part 13 placed on the support 11. and having a slot 14 extending along the Y axis mentioned above, slot 14 which is crossed by the central stud 12 and by two tenons 15 driven into the support 11.
• the central stud 12 has a diameter large enough to elastically deform the slot 14 in order to hold the adjustment part 13 in position by elastic clamping.
• the two tenons 15 guide the adjustment part 13 in translation along the Y axis when sufficient force is applied to this part 13 to adjust the unbalance of the balance 2.
• the pendulum assembly 2 - support 3 - flexible pivot 4 of oscillator 1, 1 ' can be made of different materials, for example silicon, silicon covered with oxide, glass, sapphire, quartz, metallic glass, a metal or alloy such as nickel, nickel alloy, steel, beryllium copper or nickel silver. Depending on the material chosen, it can be obtained by etching (in particular deep reactive ionic etching called DRIE), LIGA, milling, electroerosion, molding or the like.
• the set 2, 3, 4 can be monolithic.
• the present invention is applicable to other flexible pivots than separate cross blades, in particular to non-separate cross blades and to offset center of rotation (RCC) pivots.
• RRC center of rotation
• the flexible pivot 4 could comprise, in addition to the elastic blades 5, 6, additional elastic blades, for example blades superimposed on the blades 5, 6 to increase its stiffness in the direction of the height.
• the Y axis is an axis of symmetry of the flexible pivot and is also an axis of symmetry for the points of junction of the flexible pivot to the balance and for the points of junction of the flexible pivot to the support, in orthogonal projection in a plane perpendicular to the virtual axis of rotation.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
• Electric Clocks (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=67262146

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• 2020
  • 2020-07-07 JP JP2022500954A patent/JP2022539880A/ja active Pending
  • 2020-07-07 EP EP20737596.5A patent/EP3997525A1/de active Pending
  • 2020-07-07 US US17/626,303 patent/US20220317628A1/en active Pending
  • 2020-07-07 CN CN202080045111.8A patent/CN114127641B/zh active Active
  • 2020-07-07 WO PCT/IB2020/056370 patent/WO2021009613A1/fr unknown

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