Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-01-25
2001-12-18
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S156010, C310S012060, C310S014000, C310S034000
Reexamination Certificate
active
06331746
ABSTRACT:
BACKGROUND OP THE INVENTION
1. Field of the Invention
The present invention relates to the structure of a single-phase-structure actuator, and more particularly to a rotor structure of an actuator, which is easy to assemble, has well-balanced holding torque and detent torque, and is stable repetitive rotation operation.
2. Description of the Related Art
The inventors of the present application have already proposed actuator technology for an actuator of a single-phase structure claw pole-type structure, according to which a stopper mechanism is provided internally, and a rotor is made to perform repetitive rotation operations by energizing a coil in this kind of actuator, it is desirable to enlarge the rotation angle range while ensuring detent torque.
However, generally speaking, increasing detent torque causes a narrowing of the rotation angle range and therefore the detent torque must be reduced to increase the rotation angle range. That is, detent torque and rotation angle range are reciprocal in nature. This tendency is particularly notable when a sintered high-performance rare earth magnet (for example, an Nd magnet or Sm magnet), having magnetic anisotropy (for example, polar anisotropy), is used to make an actuator smaller.
As a technique applied to rotor magnet for ensuring detent torque and increasing rotation angle range, there is a method by which, when the rotor magnet is go two poles for example, a groove or cut is formed axially in the polar center portion of one of a pair of poles (for example N pole only) to increase the rotation angle range by losing the magnetic balance between the N pole and the S pole (Refer to FIG.
5
). However, the drawback is that numerous processes are required to ensure the precision of the shape of the groove or cut portion (specifically, the central angle &agr; of the groove or cut), making processing complicated. The reason for this is because, in the case of a sintered magnet, the circumference of the magnet is polished after sintering. If there is a groove or cut in the magnet circumference, not only is it impossible to ensure cylindricity, but it is also very difficult to maintain a stable groove or cut shape. Another drawback is that machine processing of the groove or cut raises increase in costs.
Therefore, in consideration of magnet processing, precision maintenance, and costs, it is desirable that the shape of the circumference of a magnet is a cylindrical shape without any groove or cut.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of he present invention to provide a rotor magnet structure in single phase-structure actuator having characteristics herein detent torque is fully assured, and a large rotation angle range is also provided.
To solve the above-mentioned problems, the present invention is directed to a single phase-structure actuator, wherein a rotor magnet is rotatably disposed by way of a minute gap inside an armature with a coil winding around the armature yoke characterized in that the above-mentioned rotor magnet is constituted by a plurality of magnets connected in the axial direction, and magnetic poles of magnets are mutually shifted in the circumferential direction.
Further, in another aspect of the present invention, there is proposed a single phase-structure claw pole-type actuator comprising a stator assembly comprising an armature composed of (a) a stator yoke composed of a pair of donut-shaped flat yokes made of a soft-magnetic material, a pole tooth which protrudes in the axial direction from the inner rim of this flat yoke and extends in the circumferential direction, and a cylindrical ring which extends in the same direction as said pole tooth on the outer rim of said yoke, and (b)a coil formed of a winding of an insulating wire which is disposed within an annular concave coil holder portion, which is formed by said flat yokes, pole teeth, and cylindrical ring of said stator yoke, and (c) flanges with bearings on both end faces of said armature, and a rotor equipped with a field magnet consisting of a permanent magnet rotor (hereinafter referred to as “rotor magnet”) disposed to face said pole teeth of said stator yoke by way of a minute gap, characterized in that said rotor magnet is constituted by connecting a plurality of magnets in the axial direction, and the magnetic poles of each magnet are mutually shifted in the circumferential direction.
Further, the actuator is characterized in that the outside diameter of the rotor magnet is less than 3 mm, and all outside diameter dimensions are equal.
Further, the actuator is characterized in that the length of each magnet in the axial direction is equal.
Further, the actuator is characterized in that each magnet has magnetic anisotropy, and the rotor magnet is constituted from two magnets.
Further, the actuator is characterized in that the amount of shift in the clrcumferential direction of each magnet counterpart ranges within an electrical angle of 10-60 (degrees).
Further, the actuator is characterized in that a spacer having a diameter equal to or smaller than the outermost diameter of a rotor magnet is provided on the connecting portion of the magnet.
Further, the actuator is characterized in that one or more pairs of protrusions and depressions for circumferential positioning of the magnet are provided on an opposing surface of each magnet and the spacer.
Further, the actuator is characterized in that a positioning groove or hole for circumferential positioning of the rotor magnet is provided on the end face of the magnet.
Further, the actuator having a plurality of magnets are bonded and affixed by way of a spacer, is characterized in that an adhesive recess is provided in the vicinity of the center hole of the rotor magnet, or on the spacer, or on both thereof.
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patent: 3454801 (1969-07-01), Suzuki et al.
patent: 4333026 (1982-06-01), Bock et al.
patent: 5126605 (1992-06-01), Palmero
patent: 5691583 (1997-11-01), Suzuki et al.
patent: 5986379 (1999-11-01), Hollenbeck et al.
patent: 5996554 (1999-12-01), Tojo et al.
patent: 6046519 (2000-04-01), Hanazumi et al.
patent: JP/08340652 (1996-12-01), None
patent: 00 10 1462 (2000-07-01), None
patent: WO97/18616 (1996-11-01), None
Fujitani Sakae
Kagawa Masaki
Suzuki Yuzuru
Lam Thanh
Minebea Co. Ltd.
Ramirez Nestor
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