EP3824353A1 - Flexure pivot oscillator insensitive to gravity - Google Patents
Flexure pivot oscillator insensitive to gravityInfo
- Publication number
- EP3824353A1 EP3824353A1 EP19737760.9A EP19737760A EP3824353A1 EP 3824353 A1 EP3824353 A1 EP 3824353A1 EP 19737760 A EP19737760 A EP 19737760A EP 3824353 A1 EP3824353 A1 EP 3824353A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- elements
- mechanical oscillator
- pair
- rigid intermediate
- intermediate body
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005484 gravity Effects 0.000 title claims description 54
- 230000010355 oscillation Effects 0.000 claims abstract description 22
- 230000000694 effects Effects 0.000 claims description 12
- 230000007246 mechanism Effects 0.000 claims description 6
- 230000009975 flexible effect Effects 0.000 claims description 4
- 230000035945 sensitivity Effects 0.000 claims description 3
- 230000009022 nonlinear effect Effects 0.000 claims 1
- 238000013461 design Methods 0.000 description 12
- 230000007547 defect Effects 0.000 description 6
- 230000003071 parasitic effect Effects 0.000 description 5
- 238000005452 bending Methods 0.000 description 4
- 238000005381 potential energy Methods 0.000 description 4
- 238000013519 translation Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 208000031872 Body Remains Diseases 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000000708 deep reactive-ion etching Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000012886 linear function Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
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
- G04B17/04—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
- G04B17/20—Compensation of mechanisms for stabilising frequency
- G04B17/26—Compensation of mechanisms for stabilising frequency for the effect of variations of the impulses
-
- 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 the field of flexure pivots. More particularly, it relates to flexure pivots which are insensitive to gravity, i.e. perform similarly independent of their orientation, and can have a linear restoring torque. Such flexure pivots are particularly suitable for use in mechanical oscillators in timepieces, however this is not the only use of such pivots.
- the time base used in all mechanical watches is a harmonic oscillator consisting of a spiral spring attached to a balance wheel having a rigid pivot rotating on jeweled bearings, see Figure 1 (a).
- the pivoting motion on bearings causes significant friction and decreases watch autonomy as well as oscillator quality factor. Note that quality factor is believed to be the most significant indicator of chronometric performance [3].
- flexure pivots provide an elastic restoring force so can be harmonic oscillators.
- their role as time bases is limited by the following factors:
- Limitation 1 Spring restoring torque can be a non-linear function of rotation angle, which affects isochronism.
- Limitation 2 Flexure pivot kinematics closely approximate rotational motion around a fixed axis but small translation can occur as angular rotation increases, a so-called parasitic shift.
- Limitation 3 Spring stiffness can be affected by the orientation of gravity.
- Limitation 4 Limited stroke and high frequency make it difficult to maintain and count oscillations using classical watch escapements.
- Limitation 5 Flexure pivots may have a 3D structure making them difficult to fit into a wristwatch.
- Goal 1 Gravity insensitivity.
- Goal 2 Maximum angular stroke for a given beam aspect ratio as well as admissible stress and Young's modulus (both material properties).
- Goal 3 2D or 2.5D design.
- Goal 4 Linear restoring torque.
- the aim of the invention is to at least partially attain at least one of the above- mentioned goals.
- the present invention provides a mechanical oscillator and a timepiece incorporating such a mechanical oscillator as defined in the appended claims.
- the invention provides a mechanical oscillator comprising an oscillating body, a first rigid intermediate body and a support, the first rigid intermediate body being connected to the support by a first pair of elements providing rotational guidance, the elements of said first pair being elastically substantially identical to each other and extending along respective axes which, in orthogonal projection onto a plane parallel to the oscillation plane of the oscillating body, cross at a point and are symmetric to each other with respect to a first line passing between the points of junction of said first pair of elements to the first rigid intermediate body (and between the points of junction of said first pair of elements to the support), the first intermediate body being connected to the oscillating body by at least one first further element providing relative guided mobility between the oscillating body and the first rigid intermediate body in a direction substantially parallel to said first line during regular functioning of the mechanical oscillator.
- the present invention provides a mechanical oscillator comprising an oscillating body, a first rigid intermediate body and a support, the first rigid intermediate body being connected to the oscillating body by a first pair of elements providing rotational guidance, the elements of said first pair being elastically substantially identical to each other and extending along respective axes which, in orthogonal projection onto a plane parallel to the oscillation plane of the oscillating body, cross at a point and are symmetric to each other with respect to a first line passing between the points of junction of said first pair of elements to the oscillating body (and between the points of junction of said first pair of elements to the first rigid intermediate body), the first rigid intermediate body being connected to the support by at least one first further element providing relative guided mobility between the first rigid intermediate body and the support in a direction substantially parallel to said first line during regular functioning of the mechanical oscillator.
- the rotational motion of the oscillating body relative to the support is the main motion (first-order motion) and the motion along the first line (not necessarily a pure translation) is a second-order motion.
- first-order motion the motion along the first line
- second-order motion the motion along the first line occurs during regular functioning of the oscillator and thus occurs even in the absence of any shock disrupting the functioning of the oscillator.
- the at least one first further element is indeed not pre-stressed.
- the oscillator according to the invention is a micromechanical oscillator.
- the timepiece incorporating the oscillator according to the invention may be a wristwatch or pocket watch for example.
- FIG. 1 (a) an isometric view of a rigid pivot watch time base according to the prior art (see reference [8]).
- FIG. 1 (b) an isometric view of a flexure pivot watch time base (see reference [2]).
- FIG. 23-26 three versions of a Florological oscillator with two co- struts arranged orthogonally sharing a common inertial rigid body (crown). Each of the co-struts has rigid links and ideal pivots.
- FIG. 27-29 three versions of a Florological oscillator with two co- struts arranged orthogonally sharing a common inertial rigid body (crown). Each of the co-struts has flexure pivots.
- Figure 33 a graph showing the relation between the stiffness nonlinearity of the oscillator illustrated in Figure 32 and a blade length ratio.
- FIG. 36-39 graphs showing the rate of an oscillator with two co- struts as a function of its angular position relative to gravity in its oscillation plane oriented vertically. Construction parameters of the oscillator are varied from Figure 36 to Figure 39.
- FIG. 41 -42 graphs showing the rate of an oscillator with two co- struts as a function of its angular position relative to gravity in its oscillation plane oriented vertically, as well as the rate of the same oscillator oriented horizontally. Construction parameters of the oscillator are varied from Figure 41 to Figure 42.
- Figures 2-12, 14-22 illustrate a two-degree-of-freedom oscillator that we have named a“co-strut”, which is used in our designs, as indicated below.
- the co-strut comprises a first body or“oscillating body” (1701 ; 1801 ; 1901 ;
- the rotational motion is the main motion (first-order motion).
- the motion along line (l) (not necessarily a pure translation) is a second-order motion which, like the rotational motion, occurs during regular functioning of the oscillator.
- the motion along line (l) is provided by at least one further element (1705; 1805; 1905; 2410, 2411 ; 2510, 2511 ; 2610, 2611 ; 2710, 2711 ; 2810, 2811 ; 2910; 3010; 3110, 3111 ; 1105; 1205; 1305; 45; 55; 65; 75; 85; 95) connected in series with the said pair of elements through a rigid intermediate body (1702; 1802; 1902; 2402; 2502; 2602; 2702; 2802; 2902; 3002; 3102; 1102; 1202; 1302; 42; 52; 62; 72; 82; 92) of negligible mass.
- Figures 5 and 9 illustrate co-struts where the said mobility of the said first body (2401 ; 2601 ) along line (l) is provided by a parallelogram linkage (2410, 2411 ; 2610, 2611 ).
- the links of the said parallelogram (2410, 2411 ; 2610, 2611 ) have preferably mirror symmetry with respect to line d perpendicular to line (l) and passing through (G).
- Figures 6 and 10 illustrate co-struts where the said mobility of the said first body (2501 ; 2701 ) along line (l) is provided by a Watt 4-bar linkage (2510, 2511 ; 2710, 2711 ) to make the isochronism insensitive to direction of gravity and increase the resistance of the oscillator against buckling.
- the links of the said Watt 4-bar linkage (2510, 2511 ; 2710, 2711 ) have preferably the same distance from line (d) perpendicular to line (l) and passing through (G).
- Figures 4, 8, 12 illustrate co-struts where the said mobility of the said first body (1901 ; 2801 ; 3101 ) along line (l) is provided by a pivot (O; 2810, 2811 ; 3110, 3111 ).
- the links (2810,2811 ) have preferably mirror symmetry with respect to line y passing through pivot point (O) and perpendicular to the line passing through (2806), (2808), (O) to make isochronism insensitive to direction of gravity.
- Figures 7 and 11 illustrate co-struts where the said mobility of the said first body (2901 ; 3001 ) along line (l) is provided by a double parallelogram linkage (2910; 3010) to make the isochronism insensitive to direction of gravity and increase the resistance of the oscillator against buckling.
- the links of the double parallelograms have preferably mirror symmetry with respect to line (d) perpendicular to line (l) and passing through (G).
- the stiffness of the rotational part of such co-struts is insensitive or little sensitive to gravity for the following reason.
- Any external load, e.g. the force of gravity, applied to the co-strut while the co-strut oscillation plane is oriented vertically has a first component parallel to line (l) and a second component perpendicular to line (l).
- the first component of the external load is not transmitted to the pair of elements (1798, 1799; 1898, 1899; 1998, 1999; 2498, 2499; 2598, 2599; 2698, 2699; 2798, 2799; 2898, 2899; 2998, 2999; 3098, 3099; 3198, 3199; 1198, 1199; 1298, 1299; 1398, 1399; 43, 44; 53, 54; 63, 64; 73, 74; 83, 84; 93, 94).
- the second component of the external load it has opposite effects on the elements of the said pair, i.e. one of the elements is loaded
- the oscillator comprises eleven rigid bodies: a main rigid body (2001 ), two intermediate rigid bodies (2002) and (2003), two rigid links (2004) and (2005) providing rotation for intermediate body (2002) around the gravity center (G), two rigid links (2006) and (2007) providing rotation for intermediate body (2003) around the gravity center (G), two rigid links (2016) and (2017) forming a parallelogram providing mobility of intermediate body (2002) with respect to main body (2001 ) along the x-axis, two rigid links (2022) and (2023) forming a parallelogram providing mobility of intermediate body (2003) with respect to main body (2001 ) along the y-axis.
- the main rigid body (2001 ) is an oscillating body.
- intermediate rigid bodies (2002) and (2003) and rigid links (2004), (2005), (2006), (2007), (2016), (2017), (2022) and (2023) is negligible compared to the mass of the main rigid body (2001 ).
- Intermediate rigid body (2002) is connected to the main rigid body (2001 ) by a parallelogram consisting of two links parallel to the y-axis (links (2016) and (2017)), each link has two pivots at its extremities (pivots (2016), (2019), (2020), (2021 )).
- Each of said pivots has the possibility of having elasticity providing restoring torque.
- the links are preferably at the same distance from the y-axis.
- Rigid body (2002) is connected to the ground or to a frame (or other support) (2000) by two links (2004) and (2005) remotely crossing at point G which is the pivot center of gravity.
- Each link has two pivots at its extremities (pivots (2008), (2009), (2010), (2011 )) and each of said pivots has the possibility of having elasticity providing restoring torque.
- Intermediate rigid body (2003) is connected to the main rigid body (2001 ) by a parallelogram consisting of two links parallel to the x-axis (links (2022) and (2023)), each link has two pivots at its extremities (pivots (2024), (2025), (2026), (2027)).
- Each of said pivots has the possibility of having elasticity providing restoring torque.
- the links are preferably at the same distance from the x-axis.
- Rigid body (2003) is connected to the ground or to a frame (or other support) (2000) by two links (2006) and (2007) remotely crossing at point G which is the pivot center of gravity.
- Each link has two pivots at its extremities (pivots (2012), (2013), (2014), (2015)) and each of said pivots has the possibility of having elasticity providing restoring torque.
- the pivot rotation axis is perpendicular to the x-y plane and passes through G.
- This oscillator is a 2D isostatic (statically determinate) pivot. Stiffness is insensitive or little sensitive to gravity.
- the oscillator comprises eleven rigid bodies: a main rigid body (2101 ), two intermediate rigid bodies (2102) and (2103), two rigid links (2104) and (2105) providing rotation for main body (2101 ) around the gravity center (G) with respect to intermediate rigid body (2102), two rigid links (2106) and (2107) providing rotation for main body (2101 ) around the gravity center (G) with respect to intermediate rigid body (2103), two rigid links (2117) and (2118) forming a parallelogram providing mobility of intermediate body (2102) with respect to fixed frame (support) (2100) along the x-axis, two rigid links (2123) and (2124) forming a parallelogram providing mobility of intermediate body (2103) with respect to fixed frame (support) (2100) along the y-axis.
- the main rigid body (2101 ) is an oscillating body.
- the mass of intermediate rigid bodies (2102) and (2103) and rigid links (2104), (2105), (2106), (2107), (2117), (2118), (2123) and (2124) is negligible compared to the mass of the main rigid body (2101 ).
- Intermediate rigid body (2102) is connected to the main rigid body (2101 ) by two links symmetric with respect to the x-axis (links (2104) and (2105)), each link has two pivots at its extremities (pivots (2108), (2109), (2110), (2111 )).
- Each of said pivots has the possibility of having elasticity providing restoring torque.
- Rigid body (2102) is connected to the ground or to a frame (or other support) (2100) by a parallelogram consisting of two links (2117) and (2118) parallel to the y-axis, preferably having the same distance from the y-axis.
- Each link has two pivots at its extremities (pivots (2119), (2120), (2121 ), (2122)) and each of said pivots has the possibility of having elasticity providing restoring torque.
- Intermediate rigid body (2103) is connected to the main rigid body (2101 ) by two links symmetric with respect to the y-axis (links (2106) and (2107)), each link has two pivots at its extremities (pivots (2112), (2113), (2114), (2115)).
- Each of said pivots has the possibility of having elasticity providing restoring torque.
- Rigid body (2103) is connected to the ground or to a frame (or other support) (2100) by a parallelogram consisting of two links (2123) and (2124) parallel to the x-axis, preferably having the same distance from the x-axis.
- Each link has two pivots at its extremities (pivots (2125), (2126), (2127), (2128)) and each of said pivots has the possibility of having elasticity providing restoring torque.
- the pivot rotation axis is perpendicular to the x-y plane and passes through G.
- This oscillator is a 2D isostatic (statically determinate) pivot. Stiffness is insensitive or little sensitive to gravity.
- the oscillator comprises seven rigid bodies: a main rigid body (2201 ), two intermediate rigid bodies (2202) and (2203), two rigid links (2204) and (2205) providing rotation for main body (2201 ) around the gravity center (G) with respect to intermediate rigid body (2202), two rigid links (2206) and (2207) providing rotation for main body (2201 ) around the gravity center (G) with respect to intermediate rigid body (2203).
- the main rigid body (2201 ) is an oscillating body.
- the mass of intermediate rigid bodies (2202) and (2203) and rigid links (2204), (2205), (2206), (2207) is negligible compared to the mass of the main rigid body (2201 ).
- Intermediate rigid body (2202) is connected to the main rigid body (2201 ) by two links symmetric with respect to the x-axis (links (2204) and (2205)), each link has two pivots at its extremities (pivots (2210), (2211 ), (2212), (2213)). Each of said pivots has the possibility of having elasticity providing restoring torque.
- Rigid body (2202) is connected to the ground or to a frame (or other support) (2200) by pivot (2208) where the said pivot has the possibility of having elasticity providing restoring torque.
- Pivots (2208), (2211 ) and (2213) are preferably on a straight line which is preferably parallel to the y-axis.
- Intermediate rigid body (2203) is connected to the main rigid body (2201 ) by two links symmetric with respect to the y-axis (links (2206) and (2207)), each link has two pivots at its extremities (pivots (2214), (2215), (2216), (2217)). Each of said pivots has the possibility of having elasticity providing restoring torque.
- Rigid body (2203) is connected to the ground or to a frame (or other support) (2200) by pivot (2209) where the said pivot has the possibility of having elasticity providing restoring torque.
- Pivots (2209), (2215) and (2217) are preferably on a straight line which is preferably parallel to the x-axis.
- the pivot rotation axis is perpendicular to the x-y plane and passes through G.
- This oscillator is a 2D isostatic (statically determinate) pivot. Stiffness is insensitive or little sensitive to gravity.
- This oscillator is a flexure (compliant mechanism) realization of the oscillator of Figure 23.
- the oscillator comprises three rigid bodies: a main rigid body (601 ) and two intermediate rigid bodies (602) and (603).
- the main rigid body (601 ) is an oscillating body.
- the mass of intermediate rigid bodies (602) and (603) is negligible compared to the mass of the main rigid body (601 ).
- Intermediate rigid body (602) is connected to the main rigid body (601 ) by two blades parallel to the y-axis (blades (604) and (605)) where the blades preferably are at the same distance from the y-axis.
- Rigid body (602) is connected to the ground or to a frame (or other support) (600) by two blades (610) and (611 ) remotely crossing at point G which is the pivot center of gravity. Blades (610) and (611 ) constitute an RCC pivot. Intermediate rigid body (603) is connected to the main rigid body (601 ) by two blades parallel to the x-axis (blades (606) and (607)) where the blades preferably are at the same distance from the x-axis. Rigid body (603) is connected to the ground or to a frame (or other support) (600) by two blades (608) and (609) remotely crossing at point G and constituting a further RCC pivot. The pivot rotation axis is perpendicular to the x-y plane and passes through G.
- This oscillator is a 2D isostatic (statically determinate) flexure pivot. Gravity produces axial (tensile or compressive) load and bending moment in the flexure blades. Stiffness is insensitive or little sensitive to gravity.
- This oscillator is a flexure (compliant mechanism) realization of the oscillator of Figure 24.
- the oscillator comprises three rigid bodies: a main rigid body (701 ) and two intermediate rigid bodies (702) and (703).
- the main rigid body (701 ) is an oscillating body.
- the mass of intermediate rigid bodies (702) and (703) is negligible compared to the mass of the main rigid body (701 ).
- Intermediate rigid body (702) is connected to the ground or to a frame (or other support) (700) by two blades parallel to the y-axis (blades (710) and (711 )).
- Rigid body (702) is connected to the main rigid body (701 ) by two blades (704) and (705) remotely crossing at point G which is the center of gravity of the pivot. Blades (704) and (705) constitute an RCC pivot. Intermediate rigid body (703) is connected to the ground or to a frame (or other support) (700) by two blades parallel to the x-axis (blades (708) and (709)). Rigid body (703) is connected to the main rigid body (701 ) by two blades (706) and (707) remotely crossing at point G and constituting a further RCC pivot. The pivot rotation axis is perpendicular to the x-y plane and passes through G.
- This oscillator is a 2D isostatic (statically determinate) flexure pivot. Gravity produces axial (tensile or compressive) load and bending moment in the flexure blades. The out-of-plane stiffness of the pivot is provided by the width of the blades. Stiffness is insensitive or little sensitive to gravity. [0058] Flexure-pivot oscillator #3 (see Figure 29)
- This oscillator is a flexure (compliant mechanism) realization of the oscillator of Figure 25.
- the oscillator comprises three rigid bodies: a main rigid body (1001 ) and two intermediate rigid bodies (1002) and (1003).
- the main rigid body (1001 ) is an oscillating body.
- the mass of intermediate rigid bodies (1002) and (1003) is negligible compared to the mass of the main rigid body (1001 ).
- Intermediate rigid body (1002) is connected to the ground or to a frame (or other support) (1000) by two blades crossing at point Oi (blades (1004) and (1005)).
- Rigid body (1002) is connected to the main rigid body (1001 ) by two blades (1008) and (1009) remotely crossing at point G which is the center of gravity of the pivot. Blades (1008) and (1009) constitute an RCC pivot. Intermediate rigid body (1003) is connected to the ground or to a frame (or other support) (1000) by two blades crossing at point O2 (blades (1006) and (1007)). Rigid body (1003) is connected to the main rigid body (1001 ) by two blades (1010) and (1011 ) remotely crossing at point G and constituting a further RCC pivot. The pivot rotation axis is perpendicular to the x-y plane and passes through G.
- This oscillator is a 2D isostatic (statically determinate) flexure pivot. Gravity produces axial (tensile or compressive) load and bending moment in the flexure blades. The out-of-plane stiffness of the pivot is provided by the width of the blades. Stiffness is insensitive or little sensitive to gravity.
- the design of the oscillator can be modified to produce a nonlinearity with the same magnitude as the said nonlinearity but opposite sign in order to reach isochronism.
- Figures 30 to 35 illustrate, based on an exemplary oscillator having one or more RCCs, how the nonlinearity may be cancelled.
- the stiffness of the flexure pivot may be expressed as follows: where Q is the rotation angle of the oscillator and O designates a negligible function.
- the parasitic motion of the intermediate body 2 with respect to the main body 1 is:
- the potential energy of the flexure pivot is:
- the potential energy of the spring is:
- the total potential energy is:
- the stiffness of the oscillator is:
- the linear restoring torque condition may be written as follows:
- a crossing point ratio d can be defined as follows:
- a blade length ratio l can be defined:
- the stiffness of the oscillator may be expressed as follows:
- Figure 33 represents the relative stiffness nonlinearity m versus the blade length ratio l for the oscillator shown in Figure 32.
- FEM finite element method
- k P, o (expressed in N/m) is the nominal stiffness of the parallel blades or other spring means
- kR,o (expressed in N. m/rad) is the nominal stiffness of the RCC pivot or other flexure pivot
- LR is the length of the blades of the RCC pivot or other flexure pivot.
- the said ratio R is also preferably greater than 0.02 and still preferably greater than 0.2.
- kR2,o is the nominal stiffness of these flexure pivots
- LR2 is the blade length of these flexure pivots
- 62 is their crossing ratio.
- the rigid intermediate bodies have a non-negligible mass and an unbalance is provided on the oscillating body to compensate for the effect of this non-negligible mass on the sensitivity of the stiffness and frequency to gravity.
- Figure 36 shows the rate in seconds/day of an oscillator according to the invention as a function of its angular position relative to gravity in the oscillation plane oriented vertically, with the rigid intermediate bodies having a negligible mass (considered to be zero).
- Figure 37 shows the rate in seconds/day of an oscillator according to the invention as a function of its angular position relative to gravity in the oscillation plane oriented vertically, with the rigid intermediate bodies having a non-negligible mass.
- the mass of the rigid intermediate bodies increases the rate variation. This defect may be compensated by moving the center of mass of the oscillating body by a distance ACOM from the center of rotation along an axis of symmetry of the oscillator in its oscillation plane, as shown in Figure 40.
- Figure 38 illustrates the rate in seconds/day of an oscillator according to the invention as a function of its angular position relative to gravity in the oscillation plane oriented vertically, with the rigid intermediate bodies having a negligible mass (considered to be zero) and with the offset ACOM being equal to zero (curve with the square dots), to 11 pm (curve with the triangle-shaped dots) and to 22 pm (curve with the cross-shaped dots).
- the offset ACOM in the present invention is typically of at least 3 pm, preferably of at least 5 pm, still preferably of at least 7 pm.
- weights may be fastened on the oscillating body.
- material may be removed from the oscillating body, e.g. by means of a laser.
- material may be added on one side and removed on the other side so that the mass of the oscillating body remains constant.
- the present invention also makes it possible to equalize the rates of the oscillator in the vertical and horizontal orientations.
- a is the half angle between the RCC blades (see Figure 32) or more generally between the elements of the/each pair of elements guiding the rotational motion of the oscillating body, may be selected to both minimize the rate variation of the oscillator in dependence upon its angular position relative to gravity in its oscillation plane oriented vertically and substantially equalize the rates of the oscillator in the vertical and horizontal orientations.
- Figure 42 in which the rates in the vertical and horizontal orientations are represented for an oscillator having an offset ACOM of 9 pm and a half angle a of 19.8°.
- the half angle a between the RCC blades or more generally between the elements of the/each pair of elements guiding the rotational motion of the oscillating body is preferably of at most 21.5°, still preferably of at most 21 °.
- any element of the oscillator which is similar to Figure 13(a), can be replaced by an element which is depicted in Figure 13(b)-(g) for compliant-mechanism realization.
- the elements of each pair of elements (2304, 2305; 2498, 2499;
- 2598, 2599; 2898, 2899; 2998, 2999; 3198, 3199; 1798, 1799; 1198, 1199; 43, 44; 73, 74; 2004, 2005; 610, 611 ; 2006, 2007; 608, 609; 2698, 2699; 2798, 2799; 3098, 3099; 1898, 1899; 1998, 1999; 1298, 1299; 1398, 1399; 53, 54; 63, 64; 83, 84; 93, 94; 2104, 2105; 2204, 2205; 704, 705; 1008, 1009; 2106, 2107; 706, 707; 2206, 2207; 1010, 1011 ) are coplanar and each have a 2D structure, as is the case with an RCC pivot for example, so that the oscillator can have a 2D structure.
- Figure 43 shows an example of a 3D oscillator according to the invention having two co-struts in two parallel planes, the co-struts respectively having two RCC pivots.
- the oscillator of Figure 43 may be used when a half angle a between the blades of each RCC greater than 45° is desired or when more compactness in the oscillation plane is desired, for example.
- the oscillator may have a 2D structure, i.e. when all elements for guidance in rotation and guidance along axes l, x and y are coplanar, many different designs may be considered.
- the oscillator may have the design shown in Figure 44, in particular if a half angle a between the blades of each RCC greater than 45° is desired.
- each blade or at least one of the blades may have a cross-section that varies along its length for e.g. a better distribution of the stresses in the blade and a longer angular stroke of the oscillator.
- Flowever, using blades all having the same constant cross-section may be advantageous since this limits the effect of machining tolerances on isochronism.
- the oscillator is made of silicon by an etching process such as the Deep Reactive Ion Etching, the etching defects will change the stiffness of all blades in the same manner if the blades have the same cross-section.
- any silicon dioxide layer provided on the silicon oscillator will change the stiffness of all blades in the same manner if the blades have the same cross-section.
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Abstract
Description
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Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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EP18183606 | 2018-07-16 | ||
PCT/EP2019/068840 WO2020016131A1 (en) | 2018-07-16 | 2019-07-12 | Flexure pivot oscillator insensitive to gravity |
Publications (2)
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EP3824353A1 true EP3824353A1 (en) | 2021-05-26 |
EP3824353B1 EP3824353B1 (en) | 2023-11-29 |
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Application Number | Title | Priority Date | Filing Date |
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EP19737760.9A Active EP3824353B1 (en) | 2018-07-16 | 2019-07-12 | Flexure pivot oscillator insensitive to gravity |
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EP (1) | EP3824353B1 (en) |
WO (1) | WO2020016131A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3982204A1 (en) * | 2020-10-08 | 2022-04-13 | The Swatch Group Research and Development Ltd | Timepiece resonator comprising at least one flexible guide |
EP3992729A1 (en) * | 2020-10-29 | 2022-05-04 | The Swatch Group Research and Development Ltd | Flexible guide with translation table for rotary resonator mechanism, in particular for a timepiece movement |
EP3992728A1 (en) * | 2020-10-29 | 2022-05-04 | The Swatch Group Research and Development Ltd | Flexible guide with translation table for rotary resonator mechanism, in particular for a timepiece movement |
EP4163735A1 (en) | 2021-10-05 | 2023-04-12 | Patek Philippe SA Genève | Methods for producing and adjusting an oscillator with flexible guide and timepiece movement comprising such an oscillator |
EP4202567A1 (en) * | 2021-12-22 | 2023-06-28 | Montres Breguet S.A. | Assembly of flexible head-to-tail guides for timepiece movement, in particular for a display device |
WO2024100597A1 (en) | 2022-11-09 | 2024-05-16 | Ecole Polytechnique Federale De Lausanne (Epfl) | Pivot, process for manufacturing such a pivot, oscillator comprising such a pivot, watch movement and timepiece comprising such an oscillator |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH701421B1 (en) * | 2009-07-10 | 2014-11-28 | Manuf Et Fabrique De Montres Et Chronomètres Ulysse Nardin Le Locle Sa | mechanical oscillator. |
EP3206089B1 (en) * | 2016-02-10 | 2018-12-19 | The Swatch Group Research and Development Ltd. | Timepiece resonator mechanism |
EP3312683B1 (en) * | 2016-10-18 | 2019-02-20 | ETA SA Manufacture Horlogère Suisse | Mechanical clock movement with resonator having two degrees of freedom with maintenance mechanism by a wheel rolling on a track |
CH713167B1 (en) * | 2016-11-16 | 2021-10-29 | Swatch Group Res & Dev Ltd | Protection of the blades of a mechanical watch resonator in the event of an impact. |
EP3561609B1 (en) * | 2018-04-23 | 2022-03-23 | ETA SA Manufacture Horlogère Suisse | Shock protection of a resonator mechanism with rotatable flexible guiding |
-
2019
- 2019-07-12 EP EP19737760.9A patent/EP3824353B1/en active Active
- 2019-07-12 WO PCT/EP2019/068840 patent/WO2020016131A1/en unknown
Also Published As
Publication number | Publication date |
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EP3824353B1 (en) | 2023-11-29 |
WO2020016131A1 (en) | 2020-01-23 |
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