GB945099A - Improvements in or relating to miniature direct current motors - Google Patents

Abstract

945,099. Electric motors. SIEMENS & HALSKE A.G. June 12, 1961, No. 21128/61. Heading H2A. A D.C. motor comprises a magnetized rotor control section which produces impulses in an axial stator coil, the impulses being amplified and applied to the axial coil of a second stator to cause an associated rotor driving section to rotate. In the motor shown the rotor driving section comprises a soft iron core 13 (Fig. 6) arranged between two 3-armed members 11 and 12 while the control section has a magnetized core 10 to induce magnetic poles in the members 8 and 9 as shown. Each rotor section co-operates with a respective stator comprising laminations having the shape shown in Fig. 3. The driving stator is formed from two sets of laminations 5b, 6b and 5c, 6c (Fig. 5), a soft iron ring 7 and winding 2 while the other stator comprises similar members 5, 6, 5a, 6a, 19 and 3. The driving stator winding 2 is arranged in the normally conducting output circuit of a two stage transistor amplifier (Fig. 7, not shown) and the stator coil current on connecting the motor to the supply causes the rotor to commence turning. After about a sixth of a turn the magnetized control rotor 10 induces a voltage in the control stator winding 3 which causes the transistor to be cut-off, but the rotor continues to be driven by the magnetized control rotor arms being drawn to the next stator pole until the transistor is again rendered conducting and the driving stator again becomes operative. The poles of the stator have reduced sections g, f, e (Fig. 3) over half their width, as shown at C-D, so that when the motor is stationary the rotor takes up a position in which the magnetized rotor arms are opposite the full section of the stator and subsequent energization of the motor will cause it to start and to rotate in the direction shown in Fig. 3. A magnetic coupling 16 (Fig. 5) in the output shaft permits relative rotation between the final output shaft and the rotor during overload and so prevents the rotor " sticking." A further transistor may be added to the circuit so that the output transistor is controlled during both its on and off conditions (Fig. 8, not shown). Starting may be effected by wholly mechanical means or by a device operated by the rotor control switch and mechanically coupled to the rotor. The control rotor may be magnetized by such that alternate arms are of opposite polarity and gearing may be interposed between the two rotors. In addition they may have different numbers of poles.