GB719424A - Magnetic torque transmission - Google Patents

Abstract

719,424. Magnetic couplings. HELMER, R. July 1, 1952, No. 16566/52. Class 35 An electromagnetic torque transmission device comprises a member 32 having alternate electromagnetic N, S poles with arcuate pole-shoes 32p closely adjacent to one another and a second member comprising a laminated ring 37 of high hysteresis loss material surrounding the first member 32. The invention aims to increase hysteresis to a maximum and to reduce eddy currents to a minimum, so that the torque developed between the two members of the device is practically producd by hysteresis. Such hysteresis torque is also appreciably present at synchronous speed as best seen from the curve N in Fig. 6. In order to produce the maximum hysteresis in the ring 37, the air gap 38. between the two members 32, 37 is made very small and the air gap 36 between the pole-shoes 32p is relatively small. Fig. 7 incorporates a braking coil 55 mounted on a frame 45 in which a driving shaft 33 is mounted. Both the driving and driven members 32, 37 are mounted within the frame 45. The device can be used as a dynamometer in which case the braking coils 55 can be omitted, Figs. 9, 10 (not shown). The device can also be used as a universal joint coupling and variable speed device as in Fig. 11 (not shown).