| 摘要 |
1,011,479. Commutation arrangements and core constructions for dynamo electric machines. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. March 9, 1964 [March 12, 1963], No. 9835/64. Heading H2A. [Also in Divisions G1 and H3] A self-starting D.C. motor has a permanent magnet rotor, with a non-magnetic structural member disposed between each successive pair of adjacent contiguous rotor magnet poles, co-operating with a stator having at least two coils energized through switches which operate in accordance with the rotor position such that at least one of the stator coils is always energized. As shown, the motor consists of a rotor 19 comprising pairs of oppositely poled ferrite magnet segments separated by segments O of non-magnetic material and a stator having wound main poles 3, 4, 5, 6 and unwound auxiliary poles 7, 8, 9, 10 enclosed in a housing 1. Coils on opposite poles are connected as groups to the output of a multivibrator circuit 30 (Fig. 6) and are supplied with D.C. through electronic switches 32, 33 which are controlled by the multivibrator. Attached to the rotor shaft 17 is a disc having an elongated arcuate slot which allows light from a filament lamp to fall on photo-transistor 31 and thereby change it to its other state and energize the other group of stator coils. When the light is cut off the multivibrator returns to its initial stable state. In a modification two photo-transistors may be used in a multivibrator circuit which is bi-stable. The length of the non-magnetic part O is preferably equal to either the width of a main stator pole, plus the air gap between this pole and the adjacent auxiliary pole or two-thirds of the stator main pole pitch. The motor may be modified by using an external rotor. |
