|
(11) | EP 1 239 349 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||
| (54) | Electric supply voltage system for converting kinetic energy into electric energy for the purpose of miniature devices |
| (57) The electric supply voltage system is provided with an alternating current generator,
an electrically chargeable accumulator, and a direct current generator. The alternating
current generator is provided with a rotor with permanently magnetized poles and a
stator which is provided with at least one electric winding for generating an alternating
current when the rotor moves relative to the stator. The system further comprises
an eccentric oscillatory weight for driving the rotor. The system is further provided
with an accelerating transmission included between the oscillatory weight and the
rotor, which accelerating transmission is provided with a resilient coupling, such
that the oscillatory weight can move in advance of the rotor while the rotor can reside
in one of the rest conditions. The accelerating transmission is provided with a first
transmission which is included between the oscillatory weight and a point of application
of the resilient coupling, and a second transmission which is included between a second
point of application of the resilient coupling and the rotor. |
[0001] The invention relates to an electric supply voltage system for converting kinetic energy into electric energy for the benefit of power consuming miniature devices, provided with an alternating current generator, an electrically chargeable accumulator, such as a battery, and a rectifier unit, which is arranged to charge the accumulator under supply of an alternating current generated by the alternating current generator, the alternating current generator being provided with a rotor with permanently magnetized poles, and a stator which is provided with at least one electric coil for generating the alternating current when the rotor moves relative to the stator, the system being further provided with an eccentric oscillatory weight for driving the rotor upon movement of the oscillatory weight, while between the stator and the rotor a number of stable rest conditions are present as a result of a restraining couple between rotor and stator, the system being further provided with an accelerating transmission included between the oscillatory weight and the rotor, which accelerating transmission is provided with a resilient coupling such that the oscillatory weight can move in advance of the rotor while the rotor can remain in one of the rest conditions, the oscillatory weight being capable of giving the rotor via the resilient coupling an impulse which, when sufficiently large, causes the rotor to move from one of the rest conditions to another one of the rest conditions, while the accelerating transmission provides a fixed uninterrupted coupling between the oscillatory weight and the rotor.
[0003] The known system is based on the insight that the restraining couple keeps the rotor in a particular rest condition relative to the stator, unless the oscillatory weight gives the rotor a sufficiently large impulse to move to another rest condition defined by the restraining couple. The resilient coupling permits movements of the oscillatory weight to lag behind the movements of the rotor. When through rotation the oscillatory weight exerts by way of the resilient coupling a moment of force on the rotor that is greater than the restraining couple, the rotor will move from one rest position to a next rest position. To that effect, the resilient coupling, upon the sufficiently large moment of force, causes the rotor to be triggered from the one rest condition to another rest condition, whereby the rotor wheel attains a relatively high angular speed relative to the speed of the oscillatory weight and hence generates relatively high voltage peaks in the alternating current generator. In the known system, it is thus attempted to make it possible for the alternating current generator to generate relatively high voltage peaks for supply to the rectifier unit for increasing the efficiency of the alternating current generator.
[0004] An important parameter of the known system is the angle of the oscillatory weight through which the oscillatory weight must rotate relative to the stator in order for the resilient coupling to be sufficiently tensioned (wound up or unwound if it is provided, for instance, with a spiral spring), for generating a moment of force greater than the restraining couple, so that the rotor will move from a first rest condition to a next rest condition. This angle is sometimes referred to as the clearance or dead angle. If the oscillatory weight moves through an angle less than the dead angle, no electric energy will be generated. It is therefore desired to select the dead angle to be small, for instance by increasing the spring constant of the resilient coupling or enlarging the weight of the oscillatory weight. However, this in turn entails an increase of the mechanical losses, as a result of which the speed at which the rotor will move is reduced. Thus, the amplitude and frequency of the alternating current generated will decrease, which in turn has an adverse effect on the efficiency of the system. Increasing the frequency again can be realized by enlarging the number of poles of the rotor. One of the associated disadvantages is that this renders the rotor more expensive. This example shows that in the known system, optimization of a particular property of the system, such as the dead angle, entails a possible deterioration of other properties of the system, such as the efficiency.
[0005] The parameters for dimensioning the known system include the magnitude of the weight of the oscillatory weight, a spring constant of the resilient coupling, the number of magnetic poles of the rotor and the number of windings of the at least one coil of the stator. The choice of these parameters determines inter alia the magnitude of the generated AC voltage, the frequency of the generated AC voltage, the magnitude of the dead angle, the mechanical losses in the transmission, the electric losses and the dimensions of the system. One problem of the known system is that properties of the system as mentioned above, which are determined inter alia by the parameters mentioned above, may be "at odds with each other", that is, if one of the properties is optimized by a particular dimensioning of the system based on a choice of the parameters mentioned, other properties might no longer be optimal and/or as desired. Moreover, depending on the application, there is only a limited freedom of choice of the parameters mentioned.
[0006] If the supply voltage system is used, for instance, in an ultraflat men's watch, the weight of the oscillatory weight must be selected to be low. Further, already upon a minimal movement of the system, kinetic energy should be converted into electric energy. The watch in question can be worn, for instance, by someone who moves only a little. On the other hand, account can be taken of the fact that the watch only needs a relatively low power to function properly, because the watch is only provided with hour, minute and second hands. If, on the other hand, the electric supply voltage system is used in a sports watch of a somewhat larger volume, the weight of the oscillatory weight can be increased and it can be assumed that the watch in question will move a great deal during exercise.
[0007] The object of the invention is to provide a system in which each of the properties mentioned can be dimensioned and optimized independently of each other to a higher degree, while moreover the application of the supply voltage system can be taken into account.
[0008] Another object of the invention is therefore to enable the subject system to be optimally dimensioned for the benefit of the intended miniature device for which it is to generate electric energy.
[0009] A further object of the invention is to provide the possibility of reducing the number of poles of the rotor, if such is desired, without this necessarily having an adverse effect on the efficiency of the system.
[0010] To that end, the system according to the invention is characterized in that the accelerating transmission is provided with a first transmission which is included between the oscillatory weight and a point of application of the resilient coupling, for accelerating the movement of the first point of application relative to the movement of the oscillatory weight, and a second transmission which is included between a second point of application of the resilient coupling and the rotor, for accelerating a movement of the rotor relative to a movement of the second point of application.
[0011] By virtue of the resilient coupling being included between a first transmission and a second transmission, two additional degrees of freedom have been incorporated as regards the dimensioning of the system according to the invention compared with the known system. In addition to the weight of the oscillatory weight, the spring constant of the resilient coupling, the number of poles of the rotor and the number of windings of the at least one coil of the stator, also the transmission ratio of each of the transmissions can be adjusted in order that an optimum dimensioning of the electric supply system can be obtained with regard to the intended use of the system. The actual dimensioning falls outside the framework of the present patent application. The point is that the system is provided with two additional degrees of freedom in dimensioning. When in the first transmission, for instance, a transmission ratio of 1:9 is chosen, the dead angle decreases by a factor of nine without decrease of the angle through which the resilient coupling unwinds when triggering the rotor from a rest condition. Conversely, if n=9, a spring can be used having a smaller spring constant without the dead angle changing. The consequence of the use of spring having a smaller spring constant is that the spring must be tensioned further to overcome the restraining couple, which in turn means that the spring will unwind further when triggering the rotor which, as a result, will make more revolutions. The second transmission can then cause the rotor to move even faster than the angle over which the resilient coupling unwinds when the rotor is triggered from a rest condition. As a result, the frequency and amplitude of the alternating current increase. This in turn makes it possible to reduce the number of poles of the rotor, to, for instance, a dipole, without the frequency of the alternating current signal becoming unacceptably long. The use of a dipole rotor has as an advantage that it is relatively cheap.
[0012] According to the invention, the first and the second transmission also provide an additional degree of freedom in respect of the dimensioning of the size of the system. Also, the resilient coupling further has as an advantage that it can function as a shock absorber when the oscillatory weight moves vehemently.
[0013] Briefly summarized, according to the invention, an optimal dimensioning of the system has been enabled, all depending on the application and the insight of the skilled person who will carry out the dimensioning in question.
[0014] Preferably, it holds that the resilient coupling is provided with a spring such as, for instance, a spiral spring or a spring which is in the form of a draw spring. It has been found that the spring constant of such a spring can be more easily varied without the volume of the spring thereby essentially changing. The spring in question can therefore be used well when the system is to be incorporated into a watch. What applies here, in particular, is that the first point of application is formed by a first end of the spring and the second point of application is formed by a second end of the spring. In this way, the spring properties of the spring are fully utilized. In particular, it holds here, further, that the resilient coupling comprises a spiral spring, with the first end of the spiral spring being situated on an inner side of the spring, and a second end of the spiral spring being situated on an outer side of the spring. According to this feature, the spring can most easily be incorporated into the system.
[0015] Further, it preferably holds that the rotor is connected with the casing so as to be rotatable about a first rotation axis, and the oscillatory weight is connected with the casing so as to be rotatable about a second rotation axis, which axes can optionally coincide.
[0016] When the first rotation axis and the second rotation axis coincide, oscillatory weight and rotor will generally be of stacked construction, causing the height of the system to increase. If the first rotation axis and the second rotation axis do not coincide, oscillatory weight and rotor can, if desired, be disposed next to each other, so that the height of the system, if desired, can be limited.
[0017] In particular, it holds here that the first and third rotation axes are arranged non-coaxially relative to each other and that the second and third rotation axes are arranged non-coaxially relative to each other.
[0018] It is possible here that, if desired, oscillatory weight, resilient coupling and rotor can be disposed next to each other, so that again the height of the system can be limited. However, all this depends on the desired application of the system.
[0019] EP 0,547,083 also discloses an electric supply voltage system provided with an oscillatory weight, accelerating transmission having a resilient coupling and a rotor, but there the accelerating transmission is arranged to interrupt the coupling between oscillatory weight and rotor. Consequently, this system works according to a different principle, because in the present invention the coupling between oscillatory weight and rotor concerns a fixed uninterrupted coupling.
[0020] The invention will presently be further elucidated with reference to the drawing. In the drawing:
Fig. 1 shows a first embodiment of a system according to the invention; and
Fig. 2 shows a second embodiment of a system according to the invention.
[0021] In Fig. 1 reference numeral 1 designates an electric supply voltage system according to the invention. The electric supply voltage system is arranged for converting kinetic energy into electric energy for the benefit of power consuming miniature devices such as watches.
[0022] The system 1 is provided with an alternating current generator 2, an electrically chargeable accumulator 4, such as, for instance, a chargeable lithium ion battery, and a rectifier unit 6 which is arranged to charge the accumulator 4 under supply of an alternating current generated by the alternating current generator 2. The alternating current generator 2 is provided with a rotor 8 with permanently magnetized poles 10. In this example, the rotor 8 is provided with one north pole 10.1 and one south pole 10.2. Accordingly, this concerns a dipole magnet.
[0023] The alternating current generator 2 is further provided with a coil 12 which is wound around a stator 13. The stator 13 is manufactured, for instance, from soft iron. The coil can be provided with any number of windings. In this example, the coil 12 is provided with 1,000 windings. The coil 12 is connected through an electric line 14 with the rectifier unit 16. The rotor 8 is rotatably connected with a casing 18 of the system for rotation about a first rotation axis 16. In this example, the casing 18 is schematically indicated and can consist, for instance, of a casing of a clockwork of a watch. The stator 13 is fixedly connected with the casing 18.
[0024] When the rotor 8 makes a complete revolution, in the coil 12 a complete sine of an alternating current will be generated. These alternating currents are processed by the rectifier unit 6 to obtain a direct current which is supplied via lines 20 to the accumulator 4 to keep the voltage in the accumulator 4 at a particular level. The direct voltage of the accumulator 4 is supplied via a line 22 to, in this example, a clockwork 24 of a watch, schematically represented.
[0025] Between the stator 13 which comprises the coil 12, and the rotor 8, a number of (in this example two) rest conditions are present as a result of a restraining couple between rotor and stator. This restraining couple is caused by the magnetic fields of the rotor which, as a result thereof, wants to align relative to the stator, so that the stator will comprise a largest possible flux. In this example, two rest conditions are present in which the magnetized poles of rotor 8 lie against the soft iron heads 15 of the stator. In this example, the rotor is shown in one of its rest positions. When the rotor rotates from this first rest position through 180 degrees about the first rotation axis 16, the second rest position is reached. Accordingly, this example involves two rest positions of the rotor relative to the stator.
[0026] The device is further provided with an oscillatory weight 26 which is rotatably connected with the casing 18 for rotation about a second rotation axis 28. Further, the system is provided with an accelerating transmission 30 included between the oscillatory weight 26 and the rotor 8, which is provided with a resilient coupling 32. The accelerating transmission provides a fixed coupling between the oscillatory weight and the rotor, that is to say that upon rotation of the oscillatory weight in a particular direction, the accelerating transmission will always move in a corresponding direction, and that the rotor, when it rotates, will always rotate in a direction corresponding to the rotation direction of the oscillatory weight. The resilient coupling 32 in this example is designed as a spiral spring. The accelerating transmission 30 is further provided with a first transmission 34 which is included between the oscillatory weight 26 and a point of application 35 of the spiral spring 32. This first point of application 35 is formed by a first end of the spiral spring on an inner side of the spiral spring. The first transmission 34 is arranged for accelerating the movement of the first point of application 35 relative to the movement of the oscillatory weight 26.
[0027] The accelerating transmission 30 is further provided with a second transmission 36 which is included between a second point of application 37 of the spiral spring 32 and the rotor 8. The second point of application 37 in this example is formed by a second end of the spiral spring, which in this example is situated on an outer side of the spiral spring. The first and second end of the spiral spring are rotatable about a third rotation axis 38. In this example, the first transmission 34 consists of a first gear 34.1 which is fixedly connected with the oscillatory weight 26 so as to be rotatable about the second rotation axis 28, as well as a second gear 34.2 which is fixedly connected with the first end 35 of the spiral spring 32 so as to be rotatable about the third rotation axis 38. The first gear 34.1 has more teeth than the second gear 34.2, so that, in use, the second gear 34.2, and hence the first end 35 of the spiral spring 32, will in effect move faster than the movement of the oscillatory weight 26. The second transmission 36 in this example is provided with a third gear 36.1 which is fixedly connected with the second end 37 of the spiral spring 32 so as to be rotatable about the third rotation axis 38. Further, the second transmission comprises a fourth gear 36.2 which is fixedly connected with the rotor 8 so as to be rotatable about the first rotation axis 16. The third gear 36.1 comprises more teeth than the fourth gear 36.2. As a result of all this, the accelerating transmission provides a fixed uninterrupted coupling between the oscillatory weight and the rotor.
[0028] The operation of the system is as follows. When the casing 18 is moved, the oscillatory weight 26 will start to move relative to the casing 18 in the sense that the oscillatory weight rotates through a particular angle about the second rotation axis 28. As a result, the first end of the spiral spring will, by way of the first transmission 34, rotate through a corresponding, larger angle relative to the casing 18. If the transmission ratio of the first transmission is 1:n, with n being equal to, for instance, 9, the first end of the spiral spring will rotate through an angle nine times as great as the angle through which the oscillatory weight rotates. The spiral spring is then tensioned through this angle, with the result that the spiral spring, by way of its second end and the second transmission 36, starts to exert a moment of force on the rotor 8. As long as this moment of force is less than the restraining couple between rotor and stator, the rotor will not rotate. This means that the oscillatory weight 26 can move in advance of the rotor whilst the rotor can reside in a rest position. However, when the angle through which the oscillatory weight rotates increases to the extent where the moment of force being exerted on the rotor exceeds the restraining couple, the rotor will be dislodged from its rest position to a next rest position. The spiral spring ensures that the rotor is triggered with a high speed. The rotor will thereby generally pass multiple rest conditions, so that an alternating current with a relatively high frequency and amplitude is generated. The second transmission has a transmission ratio of 1:m, with m being equal to, for instance, six, so that the rotor will rotate six times as fast as the second end of the spring. So, the second transmission also increases the speed of the rotor relative to the stator. To dislodge the rotor from a rest position, however, the second end of the spring must exert a moment of force on the second transmission that is m times greater than the restraining couple. The angle through which the oscillatory weight must turn to generate a moment of force that exceeds the restraining couple, is called the dead angle. This dead angle will decrease when n increases, m decreases, the spring constant of the spiral spring increases and/or the weight of the oscillatory weight increases.
[0029] The frequency of the alternating current is determined not only by inter alia the transmission ratio m of the second transmission and the spring constant, but also by the number of poles of the rotor. It follows from the foregoing that the dead angle and the frequency of the alternating current as a result of the first and second transmission can be varied independently of each other. By increasing the transmission ratio m, for instance, a dipole rotor can be used without the frequency of the alternating current substantially decreasing. As a result of the second transmission 36, the speed of the rotor will be greater than the speed with which the second end of the spring rotates about the third rotation axis 38. This relatively high speed in turn has as a consequence that in the coil 12 an alternating current is generated of a relatively large amplitude. As the magnitude of the first transmission 34 and the magnitude of the second transmission 36 can be varied, a desired weight of the oscillatory weight, a desired spring constant, a desired dead angle and/or a desired number of poles of the rotor and the number of windings of the coils 12 of the stator can be dimensioned depending on the application of the system, while it is moreover possible to achieve an optimum efficiency. The number of poles mentioned, the weight of the oscillatory weight, the dead angle and/or the spring constant can be selected to a large extent independently of each other, without this having great adverse consequences for the efficiency of the system, because the system, by virtue of the first and second transmission, has additional degrees of freedom which can be used for further dimensioning the system. Based on predetermined desired parameters of the system, such as, for instance, the magnitude of the oscillatory weight, the dead angle, the spring constant and the number of poles of the rotor, the magnitude of the first and the second transmission can then be partly dimensioned for an optimum efficiency in a required application. Thus, a supply voltage system for application in an ultraflat men's watch requires a relatively low power which is generated by relatively few movements of the person wearing the watch and relatively small dimensions of the system. By contrast, the application of the system in a chronograph requires a somewhat higher power, while moreover account may be taken of the fact that the magnitude of the oscillatory weight may increase whilst further it may be assumed that the number of movements of the user will also increase. In what manner dimensioning is done is therefore strongly dependent on the application of the system and falls outside the framework of the present invention.
[0030] The invention is not limited in any way to the embodiments outlined here. Thus, it is possible, instead of using a coil 12, to use a plurality of coils. Also, the rotor 8 may be provided with two or more dipoles. Adjacent poles may then include, for instance, an angle of 360:n degrees, with n=2,4,6,8, etc. In this example, the first rotation axis 16 and the second rotation axis 28 are not arranged coaxially relative to each other. However, these axes can also be arranged coaxially relative to each other, as shown in the embodiment according to Fig. 2, where parts corresponding to Fig. 1 are provided with the same reference numerals. This makes it clear that the first and second transmission have also as an advantage that the measurements and dimensions of the system can be varied. In the device according to Fig. 1, in particular the height h of the system can be limited, in particular when the rotor 8 is positioned not below, as shown in Fig. 1, but above the fourth gear 36.2. In the device according to Fig. 2 the first and the second transmission provide the possibility of limiting the width b of the system while the height h can increase with respect to the system according to Fig. 1. Also, other springs than the spiral spring can be used. To be considered are, for instance, a leaf spring or a spring in the form of a draw spring. The value of n of the first transmission 30 is preferably greater than 4. The value m of the second transmission 36 is preferably greater than 2. Further, the value of m is preferably less than n for reducing the dead angle with respect to systems not provided with the first and second transmission (n=m=1). Such variations each fall within the scope of the present invention.
1. An electric supply voltage system for converting kinetic energy into electric energy
for the benefit of power consuming miniature devices, provided with an alternating
current generator, an electrically chargeable accumulator, such as a battery, and
a rectifier unit, which is arranged to charge the accumulator under supply of an alternating
current generated by the alternating current generator, the alternating current generator
being provided with a rotor with permanently magnetized poles, and a stator which
is provided with at least one electric coil for generating the alternating current
when the rotor moves relative to the stator, the system being further provided with
an eccentric oscillatory weight for driving the rotor upon movement of the oscillatory
weight, while between the stator and the rotor a number of stable rest conditions
are present as a result of a restraining couple between rotor and stator, the system
being further provided with an accelerating transmission included between the oscillatory
weight and the rotor, which accelerating transmission is provided with a resilient
coupling, such that the oscillatory weight can move in advance of the rotor while
the rotor can reside in one of the rest conditions, the oscillatory weight being capable
of giving the rotor via the resilient coupling an impulse which, when sufficiently
large, causes the rotor to move from one of the rest conditions to another one of
the rest conditions, while the accelerating transmission provides a fixed uninterrupted
coupling between the oscillatory weight and the rotor, characterized in that the accelerating transmission is provided with a first transmission which is included
between the oscillatory weight and a point of application of the resilient coupling,
for accelerating the movement of the first point of application relative to the movement
of the oscillatory weight, and a second transmission which is included between a second
point of application of the resilient coupling and the rotor for accelerating a movement
of the rotor relative to a movement of the second point of application.
2. A system according to claim 1, characterized in that the resilient coupling is provided with a spring such as, for instance, a spiral
spring or a spring in the form of a draw spring.
3. A system according to claim 2, characterized in that the first point of application is formed by a first end of the spring and the second
point of application is formed by a second end of the spring.
4. A system according to claim 3, characterized in that the resilient coupling comprises a spiral spring, with the first end of the spiral
spring being situated on an inner side of the spring and the second end of the spiral
spring being situated on an outer side of the spring.
5. A system according to any one of the preceding claims, characterized in that the rotor is connected with a casing of the system so as to be rotatable about a
first rotation axis, and the oscillatory weight is connected with the casing so as
to be rotatable about a second rotation axis, which axes can optionally coincide.
6. A system according to claim 4, characterized in that the first and second end are rotatable about a third rotation axis.
7. A system according to claims 5 and 6, characterized in that the first and third rotation axes are arranged non-coaxially relative to each other
and that the second and third rotation axes are arranged non-coaxially relative to
each other.
8. A system according to any one of the preceding claims, characterized in that the first transmission is provided with a first gear transmission provided with at
least two gears having a mutually different number of teeth, and the second transmission
is provided with a second gear transmission provided with at least two gears having
a mutually different number of teeth.
9. A system according to claim 8, characterized in that the first transmission comprises a first and second gear, with the first gear having
a greater number of teeth than the second gear, and the second transmission comprises
a third and fourth gear, with the third gear having a greater number of teeth than
the fourth gear.
10. A system according to claim 9, characterized in that the first gear is fixedly connected with the oscillatory weight, the second gear
is fixedly connected with the first point of application of the resilient coupling,
the third gear is fixedly connected with the second point of application of the resilient
coupling, and the fourth gear is fixedly connected with the rotor.
11. A system according to claims 5, 6 and 10, characterized in that the first gear is rotatable about the second rotation axis; the second and third
gears are rotatable about the third rotation axis; and the fourth gear is rotatable
about the first rotation axis.
12. A system according to any one of the preceding claims, characterized in that the first transmission comprises a transmission of 1:n, with n being greater than
or equal to four.
13. A system according to claims 1-11, characterized in that the first transmission has a transmission ratio of 1:n and the second transmission
has a transmission ratio of 1:m, with m<n.