Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1979-09-20
1981-08-11
Duggan, Donovan F.
Electrical generator or motor structure
Dynamoelectric
Rotary
310268, 318254, H02K 1100
Patent
active
042836441
ABSTRACT:
A brushless DC motor includes a permanent field magnet secured to a rotor and having a radially directed annular surface, and two phase coil elements in the form of a sectorial loop secured to a stationary stator and disposed in a plane parallel to the annular magnet surface, the loop having circumferentially extending portions which are in inner and outer relation in respect to the center of the annular magnet surface, with the magnet and each coil element being relatively rotatable about the axis of the rotor. The mean radial distance f between the inner and outer circumferentially extending portions of each coil element and the radial width b of the annular surface of the magnet are selected as that the ratio b/f is within the range of 0.8 to 1.2 for maximizing the viscosity factor .mu. of the motor. In addition to providing the above ratio within the stated range or as an alternative thereto, the mechanical viscosity factor .mu. can be maximized by providing a reduced air gap d'=.sqroot.2d/.sqroot.ab, in which a is the mean radius of the magnet, d is the size of the air gap between the annular magnet surface and the stator, and d' has a value within the range of 0.15 to 0.30.
REFERENCES:
patent: 3867656 (1975-02-01), Mitsui et al.
patent: 3891905 (1975-06-01), Muller
patent: 4093882 (1978-06-01), Furuta
patent: 4109170 (1978-08-01), Fujita et al.
patent: 4143288 (1979-03-01), Sato
patent: 4164690 (1979-08-01), Muller et al.
Kishi Yoshio
Kondo Masayuki
Duggan Donovan F.
Eslinger Lewis H.
Sinderbrand Alvin
Sony Corporation
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