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
  • G04B1/00—Driving mechanisms
  • G04B1/10—Driving mechanisms with mainspring
  • G04B1/22—Compensation of changes in the motive power of the mainspring

Definitions

• the present invention relates to a movement for a timepiece comprising a power source mounted on a frame and having a variable output torque according to its state of charge.
• the energy source is intended to maintain the oscillatory movement of a mechanical oscillator through a finishing gear comprising a compensation device.
• the latter has an input kinematically connected to the power source, directly or via at least one mobile, and an output kinematically connected to the mechanical oscillator and is arranged to transmit a substantially constant torque to the mechanical oscillator regardless of the state of charge of the energy source.
• Such movements have been known for a long time, particularly in the field of clocks, to allow the use of a spring with a large power reserve, as a source of energy, while smoothing the inevitable torque variations. applied by this spring to the work train, these arising from the change in the state of charge of the spring during the operation of the clock. More specifically, it can be generally considered that the more a spring is loaded, the higher the torque that it transmits to the finishing gear train.
• the main object of the present invention is to propose an alternative to the mechanisms known from the prior art, by proposing a movement for a timepiece comprising a device for compensating for the variations of the torque released by a power source whose construction ensures high operating reliability while providing limited space, reasonable complexity and reasonable manufacturing costs.
• the present invention relates more particularly to a movement for a timepiece of the type mentioned above, characterized in that the compensation device comprises a cam having a periphery of variable radius extending substantially in a general plane, the variations of the radius of the cam being a function of those of the output torque of the energy source.
• the cam has a toothing disposed at its periphery.
• the compensation device further comprises an intermediate linkage mechanism arranged to mesh with the toothing of the cam and provide a kinematic connection substantially without sliding between the periphery of the cam and the finishing train.
• the compensation mechanism comprises exclusively constituents which, considered individually, are rigid.
• the movement according to the invention has a less bulky structure than the mechanisms of the prior art and less complex therefore less expensive to manufacture.
• the compensation device provides great flexibility in its construction, in particular to define the implantation of the cam in the movement.
• the intermediate link mechanism comprises a rocker pivoting about a fixed shaft on the frame and carrying a pinion having a permanent kinematic link with a wheel, mounted freely in rotation around the fixed shaft and arranged in permanent engagement with at least one mobile of the work train, the gear also being arranged in engagement, substantially without sliding, with the toothing of the cam.
• the shape of the periphery of the cam can be adjusted precisely, with great flexibility, depending on the behavior of the energy source, in terms of torque output as a function of its state while ensuring reliable transmission of energy from the power source to the mechanical oscillator.
• the pinion is arranged in engagement with a wheel of a reduction gear for to accord the characteristics of the energy source, particularly, in the case of a spring, the amplitude of its deformations, with the dimensioning and the number of teeth of the cam.
• the linking mechanism comprises an additional cam, of variable radius, kinematically connected, by its periphery, at the periphery of the first cam and, sized and such that the sum of their respective radii, taken on a segment connecting their respective centers, is constant, the additional cam being integral in rotation with a drive wheel kinematically connected to the energy source.
• the compensation device comprises a differential gear whose cam defines an input and whose output is kinematically connected to the mechanical oscillator.
• the differential has an additional input through which the load of the energy source can be realized.
• FIG. 1a shows a simplified top view of a part of a movement for a timepiece having a compensation device according to a first embodiment of the present invention
• FIG. 1b shows a simplified top view of a first detail of the movement of Figure 1a;
• Figure 2a shows a simplified cross-sectional view of the movement of Figure 1a
• FIG. 2b shows a simplified top view of a second detail of the movement, visible in Figure 2a;
• FIG. 2c represents a simplified top view of a third detail of the movement, visible in FIG. 2a, and
• FIG. 3 shows a simplified top view of a part of a movement for a timepiece having a compensation device according to a second embodiment of the present invention.
• Figure 1a shows a simplified top view of a part of a movement for a timepiece having a compensation device according to a first embodiment of the present invention. More precisely, only the elements of the movement involved in the kinematic chain relating to the transmission of energy, from the energy source to the mechanical oscillator whose oscillations are maintained by this energy, have been illustrated.
• the energy source takes the form of a barrel 1 housing a barrel spring (visible in Figure 2a), the latter being intended to maintain the oscillations of a pendulum 2, in particular by through a finishing train and an exhaust of which only the wheel 3 and the pinion 4 have been schematized.
• the mainspring spring being of conventional type, the torque that it transmits at the output, to the work train, varies according to its state of charge, in known manner, which can affect the accuracy of the operation of the balance.
• the finishing gear comprises a compensation device 5 to allow to maintain oscillations of the balance with a constant force and thus improve its accuracy of operation.
• a toothed output wheel 6 is mounted on the cylinder, being integral therewith in rotation and, being arranged in engagement with a first mobile 7 of a reduction gear of the compensation device, carried by the frame of movement (visible in Figure 2a).
• a pinion 8 of the first mobile meshes with a first wheel 9 of the wheel, which itself is engaged with a second wheel 10 of the wheel.
• the second wheel 10 is disposed in engagement with the periphery of a cam 12, toothed, advantageously having a shape substantially following an Archimedean curve. More specifically, the cam is provided at its periphery with a toothing disposed in the plane that it defines.
• the first is mounted on a rocker 13 pivoting relative to the frame of the movement, about the axis 14 of rotation of the first wheel 9.
• the second wheel 10 continuously transmits the movements of the first wheel 9 to the cam 12, whatever the value of the radius of the cam in contact with the second wheel 10.
• an output wheel 15 of the compensation device whose board here has five arms in a non-limiting manner, is mounted coaxially with the cam 12, to provide a constant torque at Finishing wheel located downstream, that is to say in the direction of the mechanical oscillator.
• the output wheel 15 meshes with a first mobile 16 of a multiplicative gear comprising, after the first mobile 16, a second mobile 17, a large average 18, a third mobile 19 and a second mobile 20 meshing with the exhaust pinion 4.
• a multiplicative gear comprising, after the first mobile 16, a second mobile 17, a large average 18, a third mobile 19 and a second mobile 20 meshing with the exhaust pinion 4.
• the number of mobile gear that has just been described is not limiting. It should be noted that the mechanical characteristics of the mainspring as well as the dimensions and the number of teeth of the cam affect the composition of the gear train which connects them to one another. Likewise, the dimensions of the cam and of the output wheel of the compensation device, the nature and the characteristics of the mechanical oscillator supplied with energy influence the composition of the multiplicative gear train.
• FIG. 2a represents a simplified cross-sectional view of the movement of FIG. 1a, on which the mainspring 22 is apparent, as well as the fact that the barrel of the barrel 1 does not have any teeth in so far as the torque transmission of its spring is carried out from the output wheel 6.
• the compensation device comprises a differential gear 23 whose cam 12 defines a first input, while the wheel 15 defines the output, constant torque.
• the differential gear 23 is mounted on the frame 24 of the movement by a central shaft 25.
• the output wheel 15 is screwed onto a core 26, free to rotate on the shaft 25 and having a radial toothing 27.
• a differential bridge 30 is screwed onto the cam 12, two satellites 31 being rotatably mounted by their respective ends, on the one hand, in the cam 12 and, on the other hand, in the differential bridge 30.
• Each of the satellites 31 comprises a pinion 32 and a wheel 33, the pinion 32 being arranged in engagement with the toothing 27 of the core 26.
• the differential gear 23 comprises a second input in the form of a wheel 35 mounted free to rotate on the central shaft 25.
• the wheel 35 carries a radial toothing 36 directed towards the shaft 25 and arranged in engagement with the wheel 33 of each of the satellites 31.
• the wheel 35 fulfills the input function of the differential to allow the winding of the barrel spring as it is best shown in Figure 2b, on which has been schematized the kinematic chain connecting an external control member 40 to this wheel 35.
• the external control member is arranged so as to drive in rotation a winding pinion 41 meshing with a crown wheel 42, itself engaged with a winding crown 43. This is arranged in engagement with the input wheel 35 of the differential gear 23, the latter ensuring the establishment of a kinematic connection between the external control member 40 and the barrel 1, as will be explained in detail below.
• a ratchet (not shown) of conventional type is also provided in the winding train to prevent unwanted rotation of the wheels when no winding operation is in progress.
• the rotation of the cam 12 is transmitted to the wheel 10, then to the wheel 9, to the mobile 7 and finally to the output wheel 6 of the barrel.
• the barrel 1 is consequently rotated in the counter-clockwise direction in FIG. 1a, reloading its spring 22 whose inner end is integral with the barrel shaft 50, fixed with respect to the frame.
• the barrel spring 22 transmits its force to the cam 12 tending to rotate it clockwise, on Figures 1a and 1b.
• This rotation of the cam is however possible only outside the rest phases of the escape wheel 3, namely when the output wheel 15 of the differential is not locked.
• the satellites 31 being integral with the cam by their respective axes, they are driven in the same rotational movement, which rolls their wheels 33 on the toothing
• the torque finally transmitted to the escape wheel 3 is constant which allows to provide the same amount of energy to the balance 2 at each pulse and to ensure excellent running accuracy.
• a carriageway 60 intended to carry a minute hand (not shown) is carried by the shaft of the large average 18 and itself carries a wheel of hours 61, intended to carry an hour hand (not shown), a timer 62 ensuring the necessary multiplication between these two bodies.
• a time setting train is thus advantageously provided for connecting the external control member to the timer 62.
• an indexing mechanism of the angular position of the barrel shaft 50 is provided and shown isolated in Figure 2c, by way of nonlimiting illustration.
• This mechanism has the shape of a wheel 70 with sawtooth toothing, integral in rotation with the barrel shaft 50 and, cooperating with a ratchet 71.
• This indexing mechanism makes it possible to adjust the angular position of the barrel shaft to control the minimum value of the output torque supplied by the barrel spring 22 which will be associated with the larger useful radius of the cam 12.
• This minimum value is predefined during the manufacture of the movement, according to the mechanical properties of the mainspring 22 used. This value generally defines the beginning of a range in which the torque delivered by the mainspring has regular variations as a function of its state of charge, typically characterized by the number of turns of the barrel.
• a stop 72 carried by the cam 12 and intended to cooperate with a fixed bearing surface 73 (shown schematically in Figure 1b) of the frame to stop the rotation of the cam when the minimum manufacturing value for the output torque of the barrel is reached.
• a similar stop may be provided to limit the reassembly when the minimum radius of the cam is reached, the latter being advantageously associated with a maximum value of the output torque provided by the mainspring 22. This value then marks the end of the range of use of the mainspring as mentioned above.
• Those skilled in the art may also provide a torque limiting mechanism of conventional type in the winding train, to avoid damaging the gears, without departing from the scope of the present invention.
• the gear train namely the wheels 6, 9 and 10 and the mobile 7, can be chosen so that the number total turns of the barrel 1, corresponding to its range of use, is associated with substantially one revolution of the cam 12.
• FIG. 3 represents a simplified top view of a part of a movement for a timepiece comprising a compensation device according to a second embodiment of the present invention.
• This second embodiment illustrates an alternative connecting mechanism to that of the first embodiment.
• the output wheel 6 of the cylinder 1 meshes with a first mobile 80 of a reduction gear, itself engaged with a second mobile 81.
• the latter drives a mobile link via a wheel 82, mounted in rotation with a first cam 83, being coaxial therewith.
• the first cam 83 is arranged engaged by its periphery, preferably by means of a toothing, with a second cam 84 which, for example, may advantageously fulfill the input function of a gear differential, similar to the differential 23 described in connection with the first embodiment.
• the two cams 83 and 84 are dimensioned such that their respective peripheries are engaged permanently.
• their respective rays are such that, when considering the rays located on the segment 85 connecting the centers of the cams, at each moment, their sum is constant.
• the respective values of their radii are adjusted in such a way that the torque supplied by the second cam 84 is constant regardless of the state of charge of the spring of the barrel 1, therefore whatever the output torque transmitted by the barrel at the exit wheel 6.
• the barrel spring when the barrel spring is discharged, its output torque decreases and the radius of the first cam increases to compensate substantially more than the decrease in the torque it receives, that is to say to transmit to the second cam 84 a torque whose value tends to increase very slightly.
• the radius of the second cam 84 decreases progressively so as to compensate exactly for the increase in the torque that the first cam 83 transmits to it, in order to globally provide a constant torque to the mechanical oscillator (not shown) disposed downstream. .
• the periphery of the cam is associated with the output of the compensation device, rather than at its input.
• the present invention is not limited by the nature of the energy source described and shown here.
• the invention allows the use of barrel springs called “slow” or low numbers of turns. This type of springs is not the most common because the output torque is high and has a significant variation between the two ends of its range of use in torque. However, they have the particular advantage of limiting the risk of sticking more common turns with springs "high speed” or high revolutions.
• the present invention can be used to support the significant torque that is transmitted to the gear train by parallel drums.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Transmission Devices (AREA)
• Springs (AREA)
• Apparatuses For Generation Of Mechanical Vibrations (AREA)
• Pens And Brushes (AREA)
• General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
• Nitrogen Condensed Heterocyclic Rings (AREA)
• Control Of Stepping Motors (AREA)
• Electromechanical Clocks (AREA)

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• 2006
  • 2006-10-19 EP EP06122619A patent/EP1914604A1/de not_active Withdrawn
• 2007
  • 2007-10-19 JP JP2009532818A patent/JP5005035B2/ja not_active Expired - Fee Related
  • 2007-10-19 DE DE602007011091T patent/DE602007011091D1/de active Active
  • 2007-10-19 CN CNA2007800388388A patent/CN101542400A/zh active Pending
  • 2007-10-19 WO PCT/EP2007/061225 patent/WO2008046916A2/fr active Application Filing
  • 2007-10-19 EP EP07821589A patent/EP2076821B1/de not_active Not-in-force
  • 2007-10-19 AT AT07821589T patent/ATE491171T1/de not_active IP Right Cessation
• 2009
  • 2009-10-29 HK HK09110065.0A patent/HK1132556A1/xx not_active IP Right Cessation

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