Patent GB-454491-A (GB)
Title: Improvements in or relating to alternating current motors
IPC: H02K19/08
Filed: 1935-03-27
Abstract: 454,491. Alternating-current motors. CACHEMAILLE, A. S., Crown House, Aldwych, London.-(Warren Telechron Co. ; Ashland, Massachusetts, U.S.A.) March 27, 1935, No. 9586. [Class 35] The stator of a single-phase alternating- current motor is formed as a transformer and comprises a magnetic, circuit embraced by a primary winding 11, Fig. 1, and a single turn low resistance secondary winding 19, these windings producing fluxes in the vicinity of the gap which are displaced substantially 90‹ spatially and in time phase, a disc rotor 21 containing magnetic material being located to intercept these fluxes at right angles to its axis of rotation. In the construction shown in Fig. 1, the disc 21 rotates inside the closed loop 19 and in close proximity to poles 17, 18 which are attached to opposite ends of the stator core 14. The direction of rotation mav be reversed by reversing the vertical position of the poles 17, 18. The loop 19 is secured by a non-magnetic strap 20. In a modification, Fig. 4, the secondary member 27 embraces the polepieces 25, 26 and may be held in position by the polepieces which tend to spread apart. The rotor may be in the form of a top which can be removed while spinning. Alternatively, there may be an upper bearing comprising two gear-wheels engaging a pinion on the rotor spindle and also engaging an idler pinion. The drive may be taken from one of the gears through a worm and worm wheel. Fig. 9 shows a motor with two stator coils 36, 37 on cores 42, 43 which are held between a rectangular magnetic base plate 41 and an upper plate 44. The upper plate has an air gap cut in the middle across which the primary flux flows in the direction of the arrow P. A closed conducting loop 47 surrounds the plate 44 and a secondary flux is established in the direction of the arrow N. A disc rotor 38 above the loop 47 and a similar one below are mounted on a common spindle 40 in such a way that their torques are additive. By correct selection of the weight, thickness and diameter of the discs and their distance from the closed loop, the rotor end thrust may be modified. The ratio of primary to secondary flux may be adjusted by varying the thickness of the edges 46 of the plate 44. In the form shown in Fig. 12, the stator cores carrying the primary windings 50, 51 are magnetically in parallel and the like poles at the ends are connected by yokes having polepiece extensions 54, 55 between which the disc 21 rotates. The closed secondary loop 56 surrounds the two primary coils and has a core piece with poles 57, 58. In order to minimize or eliminate the downward pull on the rotor, the air gap between the poles 57, 58 and the rotor tapers and is narrower at the top than at the bottom. A further modification employs a closed secondary loop 63, Fig. 18 having a portion 64 parallel with the primary flux or this portion may be bent back as shown at 65, 66, Fig. 21, to embrace the rotor disc. In the case of a synchronous motor, the disc may be of plain hardened steel or it may be of the form shown in Fig. 14. If induction motor characteristics only are required, a soft iron disc may be covered with aluminium or copper ; if the inner disc is of hardened steel, hysteresis starting and synchronizing torque will be included. In the case of a double disc motor, two different kinds of rotor may be employed.