Patent GB-659986-A (GB)
Title: Improvements in or relating to motor control systems
IPC: B66B1/30
Filed: 1949-11-29
Abstract: 659,986. Automatic speed control systems. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Nov. 29, 1949, No. 30588. Convention date, Jan. 29. [Class 38 (iv)] [Also in Group XXXVII] A motor control system comprises a gyroscope having a gyro-wheel mounted for rotation about spin, precession and torque axes and automatically rotated about the torque axis in accordance with the speed of the motor to be controlled, precession of the gyroscope regulating the energization of the motor. As shown in Fig. 1 the motor shaft 1a has secured thereto a gyroscopic unit 7 and a plurality of slip-rings 11. The unit 7 comprises a gyrowheel 17 mounted for free rotation about its axis by means of a polyphase winding 17c located in the gyro-wheel 17 which is hollowed out to receive it. The gyro-wheel is mounted in a cradle 19 which is in turn mounted for rotation about an axis BB relative to a U-shaped bracket 21 by means of bearings 23. The bracket 21 is adapted to rotate with the motor shaft 1a about the axis CC. Attached to the cradle 19 is an arm (Fig. 3) carrying a contact 25 movable between two fixed contacts 27, 29 by precession of the gyro-wheel which is adjustably restrained by a solenoid assembly 37 (Fig. 4), having an armature 39 secured to a vane 41 in turn secured to the cradle 19 by an arm 41a. The solenoid coils 45, 45a, 51, 51a, are energized for biassing the armature 39 to oppose movement due to precession of the gyro-wheel when the motor is operating. Should the motor speed vary from a predetermined value determined by the biassing of the armature 39, contact 25 will engage one or other of fixed contacts 27, 29, to complete a circuit for restoring the motor speed to its predetermined value. The electrical connections to the gyrowheel assembly are made through the sliprings 11. In a system employing the motor control (Fig. 5) the motor 1 is fed by a generator 61, the motor field being supplied from a D.C. generator 59 having a voltage regulator 59V. The generator 61 has a field winding 61f supplied from an excitor 65 having a sustaining field winding 65f and two auxiliary windings 69, 69a. The auxiliary windings are fed from the generator 59, one being adapted to oppose the winding 65f and the other to aid it according to which of the contacts 27, 29 are engaged by the gyro-wheel contact 25 upon a deviation of motor 1 speed. The gyro biassing coils 45, 51 are also fed from the generator 59 through a resistance 75, an adjustable resistance 81 being provided to vary the proportion of current to each coil. In order to prevent hunting a feedback voltage to the coils 45, 51 is provided through a transformer 83 in series with an adjustable resistor 85 across the generator 61 armature 61A. A slight oscillation may be imparted to the contact 25 for more progressive control by attaching a weight 17e to the gyrowheel or by boring a small hole in it. The motor control is particularly suitable for operating an elevator, Fig. 6 (not shown), the remainder of the elevator control being of known construction. A levelling control of known construction is also incorporated in the elevator control system, Fig. 7 (not shown).