Patent GB-881971-A (GB)
Title: Improvements relating to mechanically flexible electrical coupling devices
Inventor: KENYON HAROLD FREDERICK
IPC: H02G15/10
Filed: 1959-06-03
Abstract: 881,971. Couplings utilizing liquid conductors; couplings between relatively movable conducting parts. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. June 1, 1960 [June 3, 1959], No. 18999/59. Class 38 (1). A flexible coupling between conductive members which are liable to be misaligned or subject to transverse vibratory displacement, the one with respect to the other comprises a first part in the form of a drum through one end of which a second part in the form of a shaft extends by way of an opening which is bigger than the shaft to permit transverse play between drum and shaft, means being provided to prevent egress through said opening of conductive liquid contained in the drum and by means of which the drum and shaft are electrically connected together. The conductive members may rotate together at the same or different speeds. In the example shown in Fig. 1, the ends 44, 46 of the rotor winding of an alternator are connected to stationary supply terminals T 1 , T 2  by a double flexible coupling FC according to the invention and two liquid contact devices C 1 , C 2 . Coupling FC comprises a pair of coaxial drums 41, 42 carried by the end of the rotor R and connected respectively to the rods 44, 46, the drums being separated from each other and the rotor by insulation. Concentric shafts 1, 2 locked together by a pin 4 and insulated from each other terminate in the drums 41, 42 with flanges 39, 40 respectively, the shafts passing through aligned openings 50, 51 in the drums which are larger than the shafts for the purpose specified, the space between the shafts and the openings being filled by flexible seals 66, 67 to prevent egress of conducting liquid 55, 56 into which the flanges 39, 40 dip to connect them to the drums. The shafts rotate with the rotor and are driven thereby through a flexible shaft 57 connected to the end of shaft 1 and passing out of drum 41 through a flexible seal 68 into a tube 60 carried by drum 41. The shaft 57 has a splined or square end 59 which engages the correspondingly shaped tube 60 so as to be slidable therein to permit relative axial movement between the rotor and the shafts 1, 2 produced by thermal expansion and contraction of the alternator shaft. Sufficient space is provided between the flanges 39, 40 and the ends of the drums to allow for such movement. The outer ends of shafts 1, 2 are journalled in ball bearings 6, 7 carried by steel blocks 8, 9, attached to a fixed base B. Blocks 8, 9 carry the terminals T 1 , T 2  between which and the shafts 1, 2 respectively are defined annular spaces 13, 14 filled with mercury which is retained by pairs of plain bearings 15, 16 and 17, 18 on opposite sides of the terminals and forming with the mercury the liquid contact devices C 1 , C 2 . Fig. 6 shows an alternative form of drum and flange for a vertically arranged alternator. The lower end of the drum D has an inturned flange F 1  and the flange F 2  on the shaft S terminating in the drum has a peripheral flange F 3  overlapping flange F 1  and dipping in the conductive liquid, the depth of which at standstill is less than the height of flange F 1 .