GB721748A - Improvements in or relating to permanent magnet brakes or clutches - Google Patents

Abstract

721,748. Magnetic brakes and couplings. BAERMANN, M. June 1, 1951 [June 2, 1950; June 22, 1950; Feb. 12, 1951; Feb. 14, 1951; May 19, 1951], No. 13048/51. Class 35. [Also in Groups XXIV and XXXIV] An eddy-current brake, Fig. 5, comprises two rotatable discs 19 of ferro-magnetic material and having copper rings 21, secured to a shaft 18 to be braked, and plates 22 of non-magnetic material secured between the discs 19 by bolts 23 to a stationary part of the machine and provided with pole pieces 25, Fig. 6. Permanent magnets 29 of opposite adjacent polarities as shown are secured in a disc 26 and may be rotated relatively to the pole pieces 25 by movement of a handle 30, so that when the magnets lie directly opposite the poles 25 the brake is operative. In this position the flux from the magnets passes from the N poles through the pole pieces to the S poles by way of the air gaps and copper rings. In the inoperative position the magnets lie with their poles between the pole pieces so that the flux is shunted without passing through the copper rings. In another embodiment, Fig. 9, a brake drum 40 of ferro-magnetic material lined with a copper ring 41 is spaced by an air gap 42 from a disc 39 carrying magnets 36, ferro-magnetic bodies 37 which may form a closed path for the flux, and soft iron pole pieces 38. The magnets may be rotated by links 44 engaging a slotted rotatable disc 47. In a further embodiment two discs 68, 69 of non- magnetic material are mounted on a stationary element 67 and carry magnets 70 polarized as shown in Figs. 15 and 17. The discs may be relatively rotated through a gear wheel 71 so that the magnets may be brought into contact with one another in the inoperative position, whilst in the operative position their flux passes through a thin pole piece 75 and through a copper disc 76 to a brake drum 77. In yet another embodiment magnets are brought into contact by tilting so that the flux is shunted away from the brake drum. A magnetic fluid coupling, Figs. 21 and 22, comprises a driven shaft 106 which supports a ferro-magnetic housing 107 containing a mixture 108 of oil and iron powder. A disc 111 also of ferro-magnetic material is mounted on a shaft 110 so that in the operative position, Fig. 22, an annular magnet 113 enters the housing 107 and magnetizes the oil and powder to form a more or less rigid coupling. Specification 562,622 is referred to. Reference has been directed by the Comptroller to Specification 649,553, [Group XXXIV].