Patent Publication Number: US-2010128573-A1

Title: Clockwork

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a mechanical clockwork assembly, comprising a drive mechanism, a mechanical oscillator and a first transmission device for providing a transmission between the drive mechanism and the mechanical oscillator. An example of such a transmission device comprises an escapement wheel and an anchor cooperating therewith, wherein the escapement wheel is operatively connected to the drive mechanism and the anchor is operatively connected to the mechanical oscillator. 
     Such a known clockwork assembly is particularly suitable for use in a wristwatch, wherein the drive mechanism comprises a resilient body for driving the clockwork. The watch may in that case be provided with a manual operating device, particularly a crown, for winding up the resilient body, and/or an eccentric pendulum weight which via a mechanical rectifier is connected to the resilient body for winding up the resilient body in case of a movement of the eccentric pendulum weight during wearing the watch. 
     A drawback of the known mechanical oscillators is that their timing is not sufficiently stable as a result of which watches provided with such a known clockwork have to be regularly adjusted. 
     U.S. Pat. No. 3,937,001 describes a clockwork that is driven by a spring and controlled by an electronic circuit. One embodiment described in said patent specification, comprises a generator having a rotor that is active like a balance wheel and together with a spiral spring forms a mechanical oscillator. The mechanical oscillator provides a periodic regular reciprocal motion for controlling the clockwork&#39;s speed. 
     The clockwork according to U.S. Pat. No. 3,937,001 is furthermore provided with a mechanism for automatically winding up the spring. Said mechanism comprises an eccentric pendulum weight (central rotor  29 ) that is able to move along a circular path in the clockwork. In case of a change of the spatial orientation of the clockwork, the pendulum weight will move to the lowest point of its path due to gravity. Said motion is used to wind up the drive spring. A comparable mechanism for winding up the drive spring is shown in US patent application 2005/0041535. Here again use is made of a pendulum weight (oscillating weight  51 ). The pendulum weight is driven by a change of the spatial orientation, in case of wristwatch for instance by an incidental arm movement of the wearer of the watch, and in general has no periodic regular motion. 
     It is an object of the invention to provide a mechanical clockwork assembly having improved stability and/or a more efficient use of the mechanical energy of the drive mechanism. 
     SUMMARY OF THE INVENTION 
     According to a first aspect the invention for that purpose provides a mechanical clockwork assembly, comprising a drive mechanism, a mechanical control device comprising a mechanical oscillator and a first transmission device for providing a transmission between the drive mechanism and the mechanical oscillator, an electric generator and a second transmission device for providing a transmission between the drive mechanism and the generator, wherein the generator is spaced apart from the mechanical oscillator. 
     In the mechanical clockwork assembly according to the invention the drive mechanism drives both the mechanical oscillator via the first transmission device, as well as the generator, which is spaced apart from the mechanical oscillator, via the second transmission device in parallel. Due to this parallel drive the second transmission device can be optimised for more effectively driving the generator, for more efficiently generating electric energy. 
     In one embodiment the mechanical clockwork furthermore comprises a sensor for determining a timing of the mechanical oscillator, an actuator for adapting a timing of the mechanical oscillator, and an electronic control device connected to the sensor and the actuator, wherein the control device comprises an entry for a reference signal and wherein the control device is adapted for controlling the timing of the mechanical oscillator on the basis of the reference signal, wherein at least the control device is connected to the generator for supplying the control device with electric energy from the generator. In this way this embodiment of the clockwork assembly according to the invention is on the one hand provided with an electronic control for controlling the timing of the mechanical oscillator. 
     At least the control device is supplied with the electric energy from the generator. In one embodiment the sensor and/or actuator are also connected to be supplied with electric energy from the generator. 
     In one embodiment the clockwork assembly further comprises a crystal oscillator, preferably a quartz oscillator, connected to the entry of the control device, for providing the reference signal. By controlling the timing of the mechanical oscillator on the basis of an accurate crystal oscillator, such as for instance a quartz oscillator, a highly improved stability of the timing of the mechanical oscillator can be achieved. In one embodiment the crystal oscillator is connected to be supplied with electric energy from the generator. 
     In a further embodiment the clockwork assembly further comprises a receiver connected to the entry of the control device for wireless reception of the reference signal. In one embodiment the receiver is adapted for radiographic reception of a time signal. The timing of the mechanical oscillator can be controlled and/or regularly calibrated to a time signal, for instance from an atomic clock, that is transmitted via a radio transmitter. An example of such a time signal is the so-called “DCF-radio time signal”. In one embodiment the receiver is connected to be supplied with electric energy from the generator. 
     In a simple embodiment the second transmission device is at least partially connected in parallel to the first transmission device. A part of the first transmission device and a part of the second transmission device may in that case coincide. The first and second transmission device may utilise a common transmission member, which has preferably been placed at the side of the drive mechanism. 
     In one embodiment the first transmission device comprises an escapement wheel and an anchor cooperating therewith, wherein the escapement wheel is operatively connected to the drive mechanism and the anchor is operatively connected to the mechanical oscillator. 
     In one embodiment the sensor and/or the actuator comprise a magnet and a coil placed close to the magnet, wherein the magnet is operatively connected to the escapement wheel, the anchor or the mechanical oscillator, wherein the magnet due to a movement of the escapement wheel, the anchor or the mechanical oscillator is movable with respect to the coil. Due to the escapement wheel, the anchor or the mechanical oscillator moving the magnet with respect to the coil, the coil is subjected to a changing magnetic field, which as a result will influence the coil with a same timing as the timing of the mechanical oscillator. On the basis of signals from the coil the timing of the mechanical oscillator can be determined and in the electronic control circuit be compared to the timing of the reference signal. The sensor is therefore formed by the combination of a magnet and a coil. 
     If the timing of the mechanical oscillator runs ahead of the timing of the reference signal the coil can be connected for decelerating the magnet, for instance by short-circuiting the coil. If the timing of the mechanical oscillator runs behind the timing of the reference signal, the coil can be controlled for accelerating the magnet, for instance by sending a periodic current or current pulses through the coil. The combination of the magnet and the coil thus also forms the actuator. 
     In one embodiment the magnet is placed on the escapement wheel. When operative the escapement wheel makes a rotary motion, wherein the magnet in each revolution of the escapement wheel is moved past the coil. A current pulse is then generated in the coil with a frequency corresponding with the rotation frequency of the escapement wheel. In one embodiment the escapement wheel may be provided with several magnets, wherein each magnet is capable of generating a current pulse in the coil. 
     In one embodiment the magnet is placed on the anchor or the mechanical oscillator. When operative the magnet now carries out an oscillating motion. When the coil is placed near the centre of the oscillating motion, the magnet will generate current pulses in the coil having double the frequency of the frequency of the oscillating motion. 
     In one embodiment the sensor and/or actuator comprises two adjacent magnets, wherein the magnets are oriented with opposite earth poles to the coil. Due to this embodiment an alternating current signal is generated in the coil having a timing that is a measure for the timing of the mechanical oscillator. On the basis of the measurements of the alternating current or a quantity derived therefrom, for instance an alternating voltage over a resistance through which the alternating current at least partially runs, the timing of the mechanical oscillator can be determined and can be compared in the electronic control circuit to the timing of the reference signal. 
     In one embodiment the mechanical oscillator comprises a balance wheel placed so as to be rotatable on a first axis and a device for exerting a backward driving force on the balance wheel that is substantially proportional to a deflection of the balance wheel from a balance position. In one embodiment the device comprises a first resilient body, particularly a spiral spring, wherein the first resilient body with a first end is connected to the balance wheel or the first axis and with a second end is connected to a frame or housing of the clockwork assembly. In one embodiment the magnet is operatively connected to the balance wheel or the first axis. In one embodiment the magnet has been placed near the circumferential edge of the balance wheel thereon. By placing the magnet near the circumferential edge the coil, using relatively little force, is nonetheless capable of exerting large torque on the balance wheel to bring the timing of the balance wheel in conformity with the timing of the crystal oscillator. 
     In one embodiment the actuator is operatively connected to the first resilient body for adapting a spring constant of the first resilient body. In one embodiment the actuator comprises means for adapting the length of the first resilient body. 
     In one embodiment the sensor registers the timing of the mechanical oscillator on the basis of a varying reluctance or varying capacity. 
     In one embodiment the clockwork assembly comprises a storage device for electric energy, and particularly a capacitor or rechargeable battery, for at least temporarily storing electric energy originating from the generator. The battery may then serve as energy source for the various electronic components. 
     In a simple embodiment the drive mechanism comprises a second resilient body for driving the clockwork. The drive mechanism may in that case comprise a manual operating device, particularly a crown, for winding up the second resilient body. Instead of or in combination therewith the drive mechanism may comprise an eccentric pendulum weight which via a mechanical rectifier is connected to the second resilient body for winding up the second resilient body in case of a movement of the eccentric pendulum weight. 
     In one embodiment the second transmission device comprises a first and a second element that have been placed so as to be rotatable with respect to each other, wherein the first element is drivably connected to the drive mechanism and wherein the generator is drivably connected to the second element, and wherein the second transmission device comprises a third resilient body which with a first end is fixedly connected to the first element and with a second end is fixedly connected to the second element. The clockwork assembly is provided with a generator having a separate resilient transmission, as a result of which the generator during short periods can be driven with a relatively high angular speed and thus is capable of providing a high voltage. Not only does such a generator have a better efficiency for generating electric energy, but it is also advantageous in combination with a storage device for electric energy, particularly a capacitor or rechargeable battery, for storing electric energy coming from the generator and for feeding the control device, the sensor and/or the actuator. The voltage generated by the generator can be used for recharging the storage device, if this voltage exceeds a minimum loading voltage determined by the storage device. 
     In one embodiment the generator comprises a rotor wheel connected to a driving shaft which rotor wheel is provided with magnetic earth poles and a stator having a number of windings, for supplying electric voltage. Due to the restraining torque between the rotor wheel and the stator, the rotor wheel is retained with respect to the stator in one of its rest positions. The drive mechanism will wind up the third resilient body, wherein the speed of winding up preferably is controlled by the mechanical oscillator, until the moment on which the spring force of the third resilient body becomes substantially equal to the restraining torque of the generator. At that moment the restraining torque is no longer able to hold the rotor wheel, wherein the potential energy stored in the third resilient body is released for accelerating the rotor wheel. 
     As an alternative for the restraining torque of the generator one embodiment of the clockwork assembly further comprises a blocking device that engages onto the second element for blocking a rotation of the second element, wherein the blocking mechanism is drivably coupled to the mechanical oscillator for periodically releasing the second element for driving the generator and subsequently blocking the rotation of the second element again. In this embodiment stopping the rotor wheel is independent of the restraining torque of the generator. On the one hand a generator having a small restraining torque can thus be utilised. On the other hand the third resilient body can be wound up to a spring force exceeding the restraining torque. Due to the higher spring force the acceleration of the rotor wheel may be higher, and the generator is thus able to supply a higher voltage. 
     According to a further aspect the invention provides a clock, particularly a watch, provided with a clockwork assembly as described above. 
     The aspects and measures described in this description and claims of the application and/or shown in the drawings of this application may where possible also be used individually. Said individual aspects, such as the control device, a second transmission device having a blocking mechanism that is drivably coupled to the mechanical oscillator, and an actuator for adapting a spring constant, particularly for adapting the length of the spring, and other aspects may be the subject of divisional patent applications relating thereto. This particularly applies to the measures and aspects that are described per se in the sub claims. 
    
    
     
       SHORT DESCRIPTION OF THE DRAWINGS 
       The invention will be elucidated on the basis of a number of exemplary embodiments shown in the attached drawings, in which: 
         FIG. 1  shows a schematic view of an exemplary embodiment of a clockwork assembly according to the invention; 
         FIG. 2  shows a schematic view of a further exemplary embodiment of a transmission device for driving the generator; and 
         FIG. 3  shows a schematic view of a further exemplary embodiment of an actuator for adapting the timing of the mechanical oscillator. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The exemplary embodiment of a clockwork assembly  1  as shown in  FIG. 1 , comprises a drive mechanism in the shape of a drum  2  having a spring (not shown) placed therein for driving the clockwork assembly  1 . The spring may in the known manner be wound up via a manual operation or an eccentric pendulum weight. 
     The drum  2  has been provided with a gear wheel  21  coupled to a first transmission device comprising:
         a first shaft  3  having a first gear wheel  31  and a first pinion  32 , wherein the first gear wheel  31  and the first pinion  32  are rotation-fixedly connected to the shaft  3 , wherein the gear wheel  21  of the drum  2  and the first pinion  32  mesh;   a second shaft  4  having a second gear wheel  41  and a second pinion  42 , wherein the second gear wheel  41  and the second pinion  42  are rotation-fixedly connected to the shaft  4 , wherein the first gear wheel  31  and the second pinion  42  mesh;   a third shaft  5  having an escapement wheel  51  and a third pinion  52 , wherein the escapement wheel  51  and the third pinion  52  are rotation-fixedly connected to the shaft  5 , wherein the second gear wheel  41  the third pinion  52  mesh; and   an anchor  6  cooperating with the escapement wheel  51  and operatively connected to the mechanical oscillator  7 .       

     The mechanical oscillator  7  comprises a balance wheel  72  that is rotation-fixedly connected to a fourth shaft  71 , which balance wheel is able to carry out an oscillating rotary motion around said shaft  71 . The oscillator  7  further comprises a spiral spring  73  which with a first end  74  is connected to the fourth shaft  71  or the balance wheel  72 , and with another end  75  can be connected to a frame or housing of the clockwork (not shown). 
     The clockwork assembly  1  is furthermore provided with a second transmission device comprising:
         the first shaft  3  having the first gear wheel  31  and the first pinion  32 , wherein the first gear wheel  31  and the first pinion  32  are rotation-fixedly connected to the shaft  3 , wherein the gear wheel  21  of the drum  2  and the first pinion  32  mesh;   the second shaft  4  having the second gear wheel  41  and the second pinion  42 , wherein the second gear wheel  41  and the second pinion  42  are rotation-fixedly connected to the shaft  4 , wherein the first gear wheel  31  and the second pinion  42  mesh;   a fifth shaft  8  having a fifth pinion  82 , wherein the fifth pinion  82  is rotation-fixedly connected to the shaft  8 , wherein the second gear wheel  41  the fifth pinion  82  mesh;   a fifth gear wheel  81  that is placed on the fifth shaft  8  so as to be rotatable, wherein the fifth gear wheel  81  and the fifth shaft  8  are connected one to the other with a spiral spring  83 , wherein the first end  84  of the spiral spring  83  is fixedly connected to the fifth shaft  8 , and a second end  85  of the spiral spring  83  which end faces away from the first end  84  is fixedly connected to the fifth gear wheel  81 ; and   wherein the fifth gear wheel  81  and a pinion  91  mesh on the axis of rotation of a generator  9  for coupling the generator  9  to the drive mechanism  2 . The second transmission device is at least partially dissimilar to the second transmission; after the second gear wheel  41  the transmission is divided into two parallel branches that ensure the transmission with the mechanical oscillator  7  on the one hand and the generator  9  on the other hand, respectively.       

     The microgenerator  9  comprises a multi-earth pole magnet  92 , for instance a resin-bound Sm 2 Co 17  magnet having fourteen earth poles, that is rotation-fixedly connected to the axis of rotation. The generator  9  furthermore comprises a stator  93  having claw-shaped earth poles that envelop a coil  94 . 
     The exemplary embodiment of  FIG. 1  further comprises an electronic control device  10 , particularly in the form of an integrated circuit (IC). The control device  10  is supplied by an accumulator  11 , in the form of a capacitor. Such a capacitor typically has a capacity of 10 micro Farad. Via a rectifier  12 , the accumulator  11  is connected to the generator  9  for charging the accumulator  11  when the generator  9  is driven. 
     The control device  10  is on the one hand connected to a device  14  for providing a reference signal, particularly a quartz oscillator or a receiver for a time signal. On the other hand the control device  10  is connected to a coil  15  placed near a magnet  16 . The coil  15  and the magnet  16  form the sensor and actuator for controlling the timing of the mechanical oscillator  7 . 
     The magnet  16  has been placed near a circumferential edge on the balance wheel  72 . In the rest position of the mechanical oscillator  7 , the coil  15  is placed near the magnet  16 . When the clockwork  1  ticks the balance wheel  72  will carry out an oscillating rotary motion and thus reciprocally move the magnet  16  along the coil  15 . 
     The coil  15  is electrically connected to a control  10  which compares the timing of a current in the coil  15  induced by the magnet  16  to the timing of the reference signal of for instance a quartz oscillator  14 . If the timing of the induced current deviates from the timing of the quartz oscillator  14 , the control  10  is able to subsequently decelerate or accelerate the motion of the magnet  16  by means of the coil  15 , for substantially controlling the timing of the mechanical oscillator  7  to be equal to the timing of the quartz oscillator  14 . 
     In the exemplary embodiment of  FIG. 1  the rotor wheel  92  is retained with respect to the stator  93  in one of its rest positions, due to the restraining torque between the rotor wheel  92  and the stator  93 . In an alternative exemplary embodiment, as shown in  FIG. 2 , the clockwork assembly is provided with a blocking mechanism in the form of a pawl  86 , that engages onto the fifth gear wheel  81  for blocking a rotation of said fifth gear wheel  81 . A spring  89  pushes with a first end  88  against the pawl  86 , so that it retains the fifth gear wheel  81  when in the rest position. In said position the drive mechanism  2  will drive the fifth pinion  82  via the second transmission device, as a result of which the spring  83  can be wound up. 
     In this exemplary embodiment a number of cams  87  have been placed on the second shaft  4 . The second shaft  4  is coupled with the mechanical oscillator  7  via the anchor  6 , the escapement wheel  51  and the third pinion  52 . Thus the rotation of the second shaft  4  is regulated by the timing of the mechanical oscillator  7 . The cams  87  have been rotary-fixedly placed on the second shaft  4  and during rotation of the second shaft  4  will periodically push away the pawl  86 , as a result of which the pawl  86  no longer retains the fifth gear wheel  81  for a certain period of time. During this period of time the spring  83  is able to drive the rotor wheel  92  for generating electric energy. In the exemplary embodiment of  FIG. 2 , resilient cams  87  are used that push away the pawl  86 , keep the pawl  86  pushed away for a certain period of time and during this time elastically bend through and subsequently release the pawl  86 , after which the pawl  86  returns to its rest position and blocks the rotation of the fifth gear wheel  81 . 
     In the exemplary embodiment of  FIG. 1  the coil  15  and the magnet  16  form the actuator for adapting the timing of the mechanical oscillator  7 . In an alternative exemplary embodiment, as shown in  FIG. 3 , an actuator is operatively connected to the spiral spring  73  of the mechanical oscillator  7  for adapting the spring constant of the spiral spring  73 . Said embodiment of the actuator comprises means for adapting the length of the spiral spring  73 . 
     For that purpose the end  75  of the spiral spring  73  is fixedly connected to a frame or housing member  20  of the clockwork. The housing member  20  has been provided with a shaft  21  and a tooth segment  22  placed on the shaft  21  so as to be rotatable, with a holder  23  for the spiral spring  73  placed at a side facing away from the teeth  24 . Due to rotation of the tooth segment  22  with respect to the housing member  20  the position where the holder  23  engages onto the spiral spring  73  and thus the length of the spiral spring  73 , can be set. The rotation of the tooth segment  22  is ensured by an electromotor  29  that drives a gear wheel  27  by means of a pinion. The gear wheel  27  is rotation-fixedly connected to a shaft  26  and a pinion  25  placed on said shaft  26 , wherein the pinion  25  and the toothed segment  22  mesh. 
     The above description is included to illustrate the operation of preferred embodiments of the invention and not to limit the scope of the invention. Starting from the above explanation many variations that fall within the spirit and scope of the present invention will be evident to an expert.