| 摘要 |
<p>898,501. Control of A.C. motors. GENERAL ELECTRIC CO. Ltd. Jan. 1, 1960 [Jan. 14, 1959], No. 1376/59. Class 38 (3). [Also in Group XX] A motor-driven X-ray table has provision for at least two separate speeds of movement, i.e. a slower initial movement, and a faster subsequent movement, with means for setting the motor into movement at first one speed and then the other. The movement may be tilting or sliding. The change from one speed to the other is obtained by switching of pole-windings in the multipolar electric motor 1 which drives the table; thus an eight-pole motor allows a differential of four times, the change-over being effected by energization of coil 19. Forward and reverse relays 6, 7 are actuated by the energizing of coils 8, 9 controlled by a tilt switch 10. In series with coils 8 and 9 is a switch 12 which, when the table is inclined, occupies the position shown, but occupies a second position when the table passes through the horizontal. To initiate movement of the table from an inclined position, tilt switch 10 is operated to energize coil 8 or 9, which, at the same time, operates contact 23 or 24 to complete a delay relay section 17. After a short time this closes contact 16, thus energizing coil 19 and causing the motor 1 to change from low speed to high speed. As contact 16 is closed, contact 13 is opened. As the table passes the horizontal position, switch 12 moves to its other position; thus current through coil 8 is interrupted, the motor stops, and the table is momentarily arrested. Current to the relay 17 is also interrupted, but the capacitor 22 serves to keep contact 13 open for a short time, after which it closes, and contact 16 opens again, upon which the table resumes motion. A pushbutton contact 15 operates a contact 14, and hence serves to stop the table, either in its momentarily stationary horizontal position or while it is moving, since contact 15 also interrupts the current to relay 17.</p> |
