JP4614510B2 - Small power generator for portable device and electronic wristwatch provided with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small power generator for a portable device that is provided in a portable device and used as, for example, a driving power source, and an electronic wristwatch including the small power generator.
[0002]
[Prior art]
For example, an electronic wristwatch uses a battery as an energy source. Batteries are consumed by use. Therefore, some conventional electronic wristwatches are equipped with a power generation device and charge a battery.
[0003]
[Problems to be solved by the invention]
However, such electronic wristwatches have problems such as 1) poor power generation efficiency, 2) large size, and 3) poor durability.
[0004]
SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to eliminate such problems, improve power generation efficiency, reduce size, and improve durability in a small power generator of a portable device.
[0005]
The second problem is to eliminate the above-mentioned problems in an electronic wristwatch, to increase power generation efficiency, to reduce the size, and to improve durability.
[0006]
[Means for Solving the Problems]
For this reason, in order to achieve the first problem, the invention described in claim 1 is a small power generator for portable equipment,
An eccentric wheel that rotates by vibration,
A speed increasing wheel train that transmits the eccentric car at an increased speed,
While receiving rotation transmission from the speed increasing wheel train and rotating, the rotor body has a permanent magnet and a rotor wheel with a magnetic ring around it,
A stator having a pair of stator portions, and having a rotor housing hole for housing the rotor wheel between the stator portions, and a gap in which the pair of stator portions are opposed to each other across the rotor housing hole; ,
A coil that generates current by magnetic flux generated in the stator;
Tona is,
The magnetic ring suppresses the generation of cogging torque by bringing the relationship between the rotation angle of the permanent magnet and the number of flux linkages linked to the coil close to a sine wave .
[0007]
According to a second aspect of the present invention, in order to achieve the second object, an electronic wristwatch is provided with the small power generator for portable devices according to the first aspect.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a plan view of a small power generator provided in an electronic wristwatch according to the present invention.
[0009]
Reference numeral 10 in the figure denotes a mechanical-electrical converter provided in the watch case. The mechanical-electrical converter 10 mainly includes a rotor wheel 20, a stator 30 including a pair of stator portions , and a coil 40.
[0010]
The rotor wheel 20 is formed by penetrating a rotor shaft 24 at the center of a circular rotor body 22. The rotor body 22 has permanent magnets 26 and 28 sandwiching the rotor shaft 24 as can be seen from the enlarged partial view of the rotor in FIG. A magnetic ring 50 is attached around the rotor body 22.
[0011]
The magnetic ring 50 is made of a magnetic material such as permalloy, pure iron, silicon steel, ferrite, and amorphous, and is provided on the outer periphery of the rotor body 22 by press-fitting or bonding.
[0012]
On the other hand, although not shown, the rotor shaft 24 is provided with a gear, and the final gear of the speed increasing wheel train 52 is engaged with the gear. The rotation of the eccentric wheel 54 is transmitted to the speed increasing wheel train 52. Thus, the eccentric wheel 54 is rotated by vibration, and the rotation of the eccentric wheel 54 is increased by the speed increasing wheel train 52 and transmitted to the rotor wheel 20.
[0013]
Such a rotor wheel 20 is housed in a rotor housing hole 32 formed between a pair of stator portions of the stator 30. The stator 30 is formed in a C-shape as a whole with a pair of stator portions facing each other via gaps 34 and 36 on both sides of the rotor housing hole 32. The coil 40 is wound around a position opposite to the position of the rotor housing hole 32.
[0014]
As a result, when the electronic wristwatch is carried around the wrist, the eccentric wheel 54 is rotated by vibration, and the rotation of the eccentric wheel 54 is accelerated by the speed increasing wheel train 52 and transmitted to the rotor wheel 20. The rotation of 20 generates a magnetic flux in the stator 30, and a current is passed through the coil 40 by the magnetic flux. The current is stored in, for example, a large capacity capacitor (not shown).
[0015]
At this time, as shown in FIG. 2, when the opening angle between the gap 34 and the permanent magnet 26 when viewed from the center of the rotor wheel 20 is the angle θ of the permanent magnet, the angle θ of the permanent magnet and the coil 40 The relationship with the number of interlinkage magnetic fluxes interlinked with each other is as shown in FIG. The symbol t in FIG. 3 is the thickness of the magnetic ring 50.
[0016]
That is, as can be seen from FIG. 3, the relationship between the angle θ of the permanent magnet and the number of flux linkages is a sine wave, and when the angle θ of the permanent magnet is 90 degrees, the thickness t of the magnetic ring 50 is 0.2 mm. In this case, it is only about 4% smaller than when the magnetic ring 50 is not attached to the rotor wheel 20.
[0017]
FIG. 4 shows the relationship between the angle θ of the permanent magnet and the cogging torque. As can be seen from FIG. 4, when the thickness t of the magnetic ring 50 is 0.2 mm, the maximum cogging torque is 2.7 × 10 ⁻⁷ N · m, which is greater than when the magnetic ring 50 is not attached to the rotor wheel 20. About 45% smaller.
[0018]
This is presumably because the magnetic ring 50 is attached around the rotor wheel 20 to increase the magnetic flux passing through the magnetic ring 50 without passing through the gaps 34 and 36.
[0019]
【The invention's effect】
As described above, according to the first aspect of the present invention, a magnetic ring is attached around the rotor wheel, the cogging torque is greatly suppressed, and the interlinkage magnetic flux is reduced only slightly. In addition to improving the power generation efficiency, it is possible to use a small eccentric vehicle, to reduce the size, and to improve the durability.
[0020]
According to the second aspect of the present invention, since the above-described small power generator is provided, the power generation efficiency of the electronic wristwatch can be improved, and the durability can be improved as well as the size can be reduced.
[Brief description of the drawings]
FIG. 1 is a plan view of a small power generator provided in an electronic wristwatch according to the present invention.
FIG. 2 is an enlarged view of the rotor part.
FIG. 3 is a graph showing a relationship between an angle θ of a permanent magnet and the number of flux linkages linked to a coil.
FIG. 4 is a graph showing a relationship between an angle θ of a permanent magnet and cogging torque.
[Explanation of symbols]
10 Mechanical-electrical converter 20 Rotor wheel 22 Rotor body 24 Rotor shaft 26/28 Permanent magnet 30 Stator 32 Rotor housing hole 34/36 Gap 40 Coil 50 Magnetic ring 52 Speed increasing wheel train 54 Eccentric wheel θ Permanent magnet angle t Magnetic Ring thickness

Claims (2)

An eccentric wheel that rotates by vibration,
A speed increasing wheel train that transmits the eccentric car at an increased speed,
While receiving rotation transmission from the speed increasing wheel train and rotating, the rotor body has a permanent magnet, and a rotor wheel having a magnetic ring attached around it,
A stator having a pair of stator portions, and having a rotor housing hole for housing the rotor wheel between the stator portions, and a gap in which the pair of stator portions are opposed to each other across the rotor housing hole; ,
A coil that generates current by magnetic flux generated in the stator;
Tona is,
The magnetic ring is a small-sized power generator for portable equipment that suppresses the generation of cogging torque by bringing the relationship between the rotation angle of the permanent magnet and the number of flux linkages linked to the coil close to a sine wave .   An electronic wristwatch comprising the small power generator for portable equipment according to claim 1.

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