GB576689A - Improvements in eddy current brakes, dynamometers and clutches - Google Patents

Abstract

576,689. Cooling electromagnetic clutches. HEENAN & FROUDE, Ltd., and HAYES, C. T. Sept. 8, 1942, No. 12633. [Class 35] [Also in Group XIX] An eddy current clutch, dynamometer, or brake of the kind having relatively rotatable toothed flux concentrating and smooth flux concentrating and smooth flux receiving members is cooled by liquid which is passed through the " air-gap " between the two members so as to be in contact with the flux receiving surface in which the eddy currents are generated. Figs. 1 and 2 show a dynamometer comprising a toothed magnetic rotor D driven by a shaft 1 mounted in bearings RB carried by end-plates 20 secured to a magnetic stator S, the bearings being carried by pedestals P which support the machine on bearings B and allow oscillation of the stator, movement of the latter being limited by a torque arm which may be connected to the stator at T. Excitation of the machine is provided by a coil 5 having a waterproof casing Y and secured by spacers 8 in an annular channel C in the stator. The stator is provided with flux receiving members in the form of steel or soft iron liners 11, 12. Water for cooling the machine is supplied through a pipe 28 to the annular channel C which is closed by a non-magnetic ring 6 having apertures through which the water is discharged into a recessed portion 9 of the rotor from which the water is driven by centrifugal action by the rotor teeth into contact with the liners 11, 12. The water passes axially along the liners and is deflected by blades 26 into a circumferential channel formed in each endplate and provided with a discharge opening 24. The blades 26 also serve to transfer to the stator any tangential forces imparted to the water by the action of the rotor. Lips 17 are provided on the liners to maintain thereon a thin film of water into which the rotor teeth dip. Water is prevented from reaching the shaft 1 and headings B, RB, by labyrinth seals formed by axial flanges 18 on the ends of the rotor and radial flanges 19 on the end plates. Diaphragms 290 serve as vacuum guards for the bearings. The ring 6 may be formed so as to supply water from the channel C nearer to the centre of the machine at a point of low pressure in the recess G. In a modified construction, Fig. 3, the water is passed axially of the machine in one direction only, being supplied through an inlet 220 to an annular channel 115 in the end-plate 52 from which the water passes over a weir 116 into the " air-gap " 118 and after flowing along the entire length of the flux receiving surfaces is discharged into an annulus 129 in the end-plate 55 which has an outlet 126. The exciting coil 45 is cooled by air blast. The depth of the rotor teeth and the overall rotor diameter may increase towards the discharge end of the machine, the stator bore being correspondingly tapered. The positions of the flux concentrating and flux receiving members may be reversed, the stator then being of toothed construction and the rotor carrying the smooth flux receiving surface.