| 摘要 |
<p>1471981 Electric motors; motor protection circuit SONY CORP 27 June 1974 [29 June 1973] 28611/74 Headings H2A and H2K To prevent damage to a brushless D.C. motor due to excessive current a transformer 15 supplying the driven circuits 3 of the motor with a control signal is provided with a temperature sensitive core and is mounted on the motor in a position to sense heat generated by an excessive current flow when the permeability of its core will decrease thereby reducing the magnetic coupling of the transformer and cutting off the control signal to the driven circuits 3, thus in turn cutting off the supply to the motor. The transformer core is a temperature-sensitive ferrite whose permeability changes abruptly at 70‹ C. Exciting windings 1 of the motor are connected between a D.C. supply 22 and the driver circuits 3 which are fed from an oscillator 16 via the transformer 15 and detecting coils 17, the detecting coils being angularly spaced at 120 degrees apart and excited by a marker magnet extending over an angle of 120 degrees on the rotor to give an indication of the rotary position of the rotor to control the current supply to the motor. The motor has a stator 21 supported on a base 20 and surrounded by a cupshaped rotor 22 on a shaft 19, the rotor carrying permanent magnets 23. The marker magnet is made of magnetic rubber.</p> |
