Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-10-12
2003-08-05
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S156010, C310S049030, C310S07500D, C968S553000
Reexamination Certificate
active
06603236
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electromagnetic converter such as a small generator, a motor and so on and to electronic equipment provided therewith, and the present invention is particularly applicable to a wrist watch and the like.
BACKGROUND ART
Conventionally, electronically-controlled mechanical timepieces hereinafter, referred to as electronically-controlled mechanical watches) are known which F, convert mechanical energy, which is generated by releasing a mainspring, into electric energy through an electromagnetic converter, control the value of a current flowing in the coil of the electromagnetic converter by actuating a rotation control means by the electric energy and display a time by driving hands fixed to a train wheel (Japanese Examined Patent Publication No. 7-119812 and Japanese Unexamined Patent Publication No. 8-50186, etc.).
Further, Japanese Unexamined Patent Publication No. 8-5758 proposes, in order to improve the efficiency for converting mechanical energy into electric energy, an arrangement using PC permalloy (hereinafter, referred to as, PC material) having a coercive force smaller than that of PB permalloy (hereinafter, referred to as PB material) so as to reduce the hysteresis loss of a stator and a coil core, which constitute the magnetic circuit of a generator in the electronically-controlled mechanical watches.
In contrast, recently proposed are electronic timepieces provided with generators (Japanese Examined Patent Publication No. 7-38029 and so on). The electronic timepiece is arranged such that the generator is assembled to a wrist watch main body. Electric energy necessary to drive the wrist watch is generated by the movement of an arm and accumulated in a capacitor and an electronic circuit is driven by the electric energy. In the wrist watch to which the generator is assembled, the power of a rotary movement weight is transmitted to the generator through a power transmission mechanism composed of a speed increasing train wheel, and electric power is generated by causing an electromagnetic inducing action on a coil due to the change of a magnetic field which is generated by the rotation of the rotor.
These generators comprise a rotor including a permanent magnet, a first yoke disposed around the rotor and a second rotor connected to the first yoke and including a coil. The second yoke is placed on the first yoke and the magnetic induction from the upper yoke to the lower yoke is secured through screws as shown in the drawings in Japanese Examined Patent Publication No. 7-38029.
The PC material, PB material and the like are ordinarily used as the material of the yokes of the magnetic converter.
In the electronic timepiece provided with the generator device, since the first yoke (stator) has no coil wound therearound, copper loss (electric resistance) is not increased by a wound coil. Thus, the PC material is used as the first yoke because it can increase a sectional area and accordingly it has magnetic flux density as small as 0.7 T and its iron loss is also small. In contrast, since the second yoke (coil core) has a coil wound therearound, when the sectional area thereof is increased, the length of a coil wire is increased and copper loss is increased thereby. Thus, the PB material is used in the second yoke because it has relatively high saturation magnetic flux density of 1.4 T, although it has iron loss larger than that of the PC material. That is, in the second yoke, the use of the PB material, which has large iron loss but can secure necessary magnetic flux even if the sectional area thereof is reduced, can decrease total loss as compared with the use of the PC material, which must increase the sectional area by which the copper loss of the winding thereof is increased, although its iron loss is low. Accordingly, the PB material is used in the second yoke.
In the electronic timepieces with the generators, when a speed increasing ratio achieved by the power transmission mechanism of an electromagnetic converter is set to about 100 in a generator, a rotor often operates at 50 to 150 Hz when the wrist watch is worn. As a result, iron loss is increased because an alternating-current magnetic field is generated to the yoke and an eddy current is generated to the material. Therefore, to develop an effective generator, a material having low iron loss is required in an alternating-current region (50-150 Hz).
When a secondary power supply such as a capacitor or the like is to be charged, a voltage effective at charging is obtained at a frequency of 50 Hz or more. Thus, a material having small iron loss in the alternating-current region is required also from this point of view.
Therefore, in the electronic timepieces provided with the generator devices, a material having small iron loss is required for the first yoke (stator) around which no coil is wounded. Whereas, a material having small iron loss and high saturation magnetic flux density is required for the second yoke (coil core) around which the coil is wound.
Further, the magnetic flux flowing in the magnetic circuit of the electronically-controlled mechanical watches is smaller by one order of magnitude as compared with that of the electronic timepieces provided with the generator devices and further the electronically-controlled mechanical watches have coil windings. Thus, even if the sectional area of the yoke of the electronic timepieces is reduced to decrease iron loss, the magnetization flux density is not saturated. Therefore, the PC material having the saturation magnetic flux density as small as 0.7 T is used in the electronic timepieces.
In the electronically-controlled mechanical watches, almost all the losses of the electromagnetic converter result from iron loss and the mechanical loss of gears and bearings (abbreviated as mechanical loss). A reason why the mechanical loss is caused by the speed increase near to 100,000 to 300,000 times, and further the mechanical loss has characteristics that it is proportional to iron loss. Therefore, reduction of iron loss is a subject for decreasing the total loss. In addition, the reduction of the iron loss is important because a duration time depends on the magnitude of the rotation load torque (magnetic torque) of the generator.
DISCLOSURE OF THE INVENTION
The present invention is an electromagnetic converter comprising a rotor arranged by including a permanent magnetic yoke disposed in the vicinity of the rotor for flowing magnetic flux and a coil disposed in the vicinity of the yoke, and the electromagnetic converter is characterized in that at least a portion of the yoke is composed of an amorphous metal magnetic material.
Further, the present invention is electronic equipment provided with the electromagnetic converter. The electronic equipment is preferably arranged, as portable type electronic equipment and most preferably arranged as, for example, a portable timepiece.
The electromagnetic converter includes a small generator, a motor and the like.
According to the present invention, the improvement of efficiency of a generator which is achieved by the reduction of iron loss can increase a duration time in the electronically-controlled mechanical watches and can reduce the size of a rotary movement weight in the electronic timepieces provided with generator devices, whereby the size and thickness of the timepieces can be reduced.
The yoke is ordinarily composed of magnetic members comprising at least two magnetic materials, and it is preferable that at least one of the magnetite members be composed of the amorphous metal magnetic material.
In the magnetic material, when magnetic flux flows, an anti-magnetic field is; produced in the direction of the flow and acts to prevent the flow of the magnetic flux. For example, when two flat-sheet-shaped magnetic materials are jointed to each other with the upper and lower surfaces thereof overlapped partially, a magnetization direction (direction in which magnetic flux flows) is the thickness direction of the magnetic materials. The intensity Hd of the anti-magnetic fi
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