Patent GB-599143-A (GB)
Title: Improvements in eddy-current dynamometers, brakes or the like
IPC: H02K49/04
Filed: 1945-03-09
Abstract: 599,143. Eddy current brakes. WINTHER, M. P. March 9, 1945, No. 5882. Convention date, March 2, 1944. [Class 103 (i)] [Also in Group XIX] In an eddy current dynamometer or brake having relatively rotatable armature and field concentrating members and having the operative surfaces in the flux gap therebetween cooled by the passage of water through the gap, the water inlets are arranged at two or more axial points to allow water to enter the gap at two or more axial points, and water outlets are arranged at two or more axial points to receive water from the gap. The cooling arrangement is an improvement on that described in Specification 576,689, [Group XIX]. As shown in Fig. 1, the stator S carries the field coil 21, and the inner face thereof is formed by four section members 24 provided with circumferential water channels 25. Water from the pipe 51 passes into the stator and is arranged to flow in one direction around the channels 25 of the first section 24, in the reverse direction in the next section, through the pipe 55 to the third section, and then in the reverse direction in the fourth section. The water then leaves the stator through the pipe 53, and is introduced into rings adjacent the gap between the stator and rotor 17 by means of branch pipes 63, 65, supported in heads 7 connecting the stator to bearing members 16. The rotor 17 has peripheral teeth 19 which pick up the water from the rings and distribute it axially inwardly as a thin film upon the insides of the two outer sections 24. Water is also introduced from the water compartments in the stator body through a port at each side of the coil 21 into a groove in a central member 33 secured between the two inner sections 24, and this is also picked up by the teeth and distributed axially outwardly upon the insides of the two inner sections 24. Crescent-shaped passages 81, Fig. 3, formed between the sections 24 provide outlets for the water from the gap, these outlets being provided with deflector pieces 83, 85, and lips 86 to prevent return of the water, and the latter passes into sumps 87 and away through pipes 89. By this arrangement, the axial distance each thin film of water needs to flow is quite short, and the teeth 19 of the rotor do not dip into the water to any appreciable extent. The inlet port at each side of the coil 21 and the openings in the rings at each end of the rotor are preferably shaped to operate as spray nozzles through which the water is sucked by the rotor teeth. Baffles 18, 20 prevent water reaching the bearings. In modifications, water is not circulated around the stator, but is introduced: (.a) direct to the gap radially and centrally, and axially, and is drained off radially; (b) along axial passages in the stator and then radially through holes in the passages leading to the gap between stator and rotor; or (c) is introduced into a bore provided in the rotor shaft, and passes to the gap through holes in the rotor communicating with the bore in the shaft. In the form shown in Fig. 8 the toothed or polar member is on the stator, and the armature is rotary. The stator S comprises an outer casing 99 attached to enclosing end rings 101 secured to three-piece magnetic rings 103 carrying field coils 105. The rings 103 are supported on trunnions 97 extending into bearings 95. The polar teeth 107 are overlapping and of known type. A central spider 113 keyed on shaft 111 has cylindrical armature sleeves 115 thereon. Cooling water is introduced through pipes 117 attached to the stator rings 103 through flexible connections 121, the water being caught up by the spider 113 and passed as a thin film through the gaps between the teeth 107 and sleeves 115, and escapes at each end into the central drain 123. Gland sleeves 127, 129, 131 prevent water reaching the bearings. The Specification as open to inspection under Sect. 91, comprises also a modification of the type shown in Fig. 8. The spider is made of two like parts bolted together, the armature sleeves are spaced apart, and water is introduced radially into this space through a pipe passing through the stator, and passes through apertures in the spider just beneath the armature sleeves where it flows through the gap between the latter and the teeth on the stator. A further construction, comprising an electromagnetic brake, is similar to that shown in Fig. 8. This subject-matter does not appear in the Specification as accepted.