GB629919A - Improvements in or relating to electro-magnetic eddy-current couplings - Google Patents

Abstract

629,919. Eddy current couplings. KREBS, E. W. Dec. 1, 1947, No. 31694. [Class 35] The driven member of an eddy current coupling constitutes a disc of magnetic material lying between two electromagnets, each having two polar members constituting rings coaxial with the axis of rotation, and in order to reduce the inertia of the driven member it has apertures lying between the aligned poles. In the form shown in Fig. 1 the two magnets A<1>, A<4> are united by circumferential bolts with distance pieces A<3> of non-magnetic material and the apertures in the disc C<2> (Figs. 2, 3) lie in each of the disc portions between the annular pole pairs N<1>, S<2> and N<2>, S<1> and are so arranged as to make the flux density in both regions the same. In a modified construction (Fig. 5), each annular pole member has a ring of pole pieces L or L<1> secured to it to form an imbricated pole structure and polepieces of unlike polarity of the two electromagnets are aligned; the apertures in the driven disc may be constituted by radial slots extending across the field area. The portion of the disc lying between two rings of apertures may be cut away, for example to form spokes, still further to reduce the inertia. The rim of the disc may carry an inserted ring of high conductivity. Ventilation may be set up by fins G, Fig. 1, and an enclosing casing G<1>.