Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1994-06-02
2000-12-26
Dougherty, Thomas M.
Electrical generator or motor structure
Dynamoelectric
Rotary
310194, 310257, 310267, H02K 3714
Patent
active
061664707
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a brushless DC motor, which has a magnetic field winding on stator yokes, a permanent magnet on a rotor, and no brush, and particularly to a motor structure.
BACKGROUND ART
Conventional brushless DC motors known include a core type motor shown in FIG. 50 and a coreless type motor as shown in FIG. 51 to FIG. 57.
As shown in FIG. 50, the above core type motor 52 has a stator yoke 53 formed by layering electromagnetic steel plates which are punched out into a certain form, and has a magnetic field coil 54 disposed in a slot section of the stator yoke 53 in the insulated state. A rotor magnet 56 is disposed on a rotor 55. And, a motor section comprises the stator yoke 53 and the rotor 55, and a circuit unit section 57 consists of a circuit element and the like.
The above coreless type motor 60 has a magnetic field coil 59, which is formed in the shape of a ring by a self-fusing line, disposed in an air-core type stator yoke 58 as shown in FIG. 51. The magnetic field coil 59 is formed as shown in, for example, FIG. 52 and FIG. 53. And, a rotor 61 is provided with a rotor magnet 63. And, the stator yoke 58 and the rotor 61 form a motor section, and a circuit unit 76 consists of a circuit element and the like.
In the motors 51 and 60 having the above structures, assembling can be made by fitting from one direction of a motor bearing supporter (boss).
The coreless type motor 60 is known described in, for example, Japanese Patent Application Laid-open Print No. 23754/1989. The brushless DC motor 60 of this type has a rotor 61 consisted of a cup-shaped rotor yoke 62, a ring-shaped rotor magnet 63 adhered to the inner periphery of the rotor yoke, and a shaft 65 fitted to the center of the rotor yoke 62 with a bush 64 as shown in FIG. 54. In the figure, 66 represents a turn table.
As shown in FIG. 55, a stator 67 comprises first and second stator yokes 68, 69 made of a soft magnetic metal plate, and a coil unit 70 disposed between the stator yokes 68, 69. Both the stator yokes 68, 69 have magnetic poles 68a, 69a formed which are extended from the center radially toward outward and bent at right angles, and have rings 71, 72 integrally formed at the center along the bent direction of the magnetic poles 68a, 69a. In the figure, four poles are shown.
The first stator yoke 68 and the second stator yoke 69 of the stator 67 are put together with the coil unit therebetween, the ring 71 and the other ring 72 are joined to be magnetically connected to form a magnetic circuit, keeping a certain gap from the circumferential face of the rotor magnet 63 of the rotor 61, and the magnetic poles 68a, 69a of the first and second stator yokes 68, 69 are alternately disposed in the circumferential direction.
Further, a sleeve 73 is fitted within the ring 71 of the stator 67, and the shaft 65 of the rotor 61 is supported in the sleeve 73 via a bearing 74. To the bottom of the sleeve 73, a base plate 75 is fitted to support the stator 67, and a circuit board 76 is fixed to the base plate 75. In the figure, 77 represents a magnetic pole sensing element to detect a magnetic pole of the rotor.
Besides, as a chucking magnet to adsorb and fix a revolving work, a chucking magnet 79 magnetized as shown in FIG. 57 has been used heretofore.
Furthermore, as brushless DC motors structured using stator yokes which are formed by bending a soft magnetic metal plate, for example, Japanese Patent Application Laid-open Print No. 23754/1989 and Japanese Patent Application Laid-open Print No. 214458/1990 are known. In such motors, magnetic poles are formed in an asymmetrical shape to shift the rotor's static stable position from the position of excitation torque 0, the magnetic poles of one stator yoke have a different shape from those of the other stator yoke, and the position of each stator is shifted to cause magnetic unbalance to shift the rotor's stable position, thereby eliminating a dead point of the motor revolution.
However, the above conventional brushless DC motors have the following structural drawba
REFERENCES:
patent: 3508091 (1970-04-01), Kavanaugh
patent: 4030005 (1977-06-01), Doemen
patent: 4099104 (1978-07-01), Muller
patent: 4529933 (1985-07-01), Bleeke
patent: 4547714 (1985-10-01), Muller
patent: 4891567 (1990-01-01), Fujitani et al.
Ito Norio
Matsuzawa Kinya
Miyazawa Hiroshi
Saito Koichi
Soya Yasushi
Dougherty Thomas M.
Seiko Epson Corporation
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