Patent GB-217610-A (GB)
Title: Improvements in and relating to polyphase asynchronous motors
IPC: H02K17/14
Filed: 1922-12-15
Abstract: 217,610. Ernstein, F. Dec. 15, 1922. Regulating switches; switches with quick action.-A polyphase squirrel-cage motor of variable pole number has on the stator a single lap winding cut at intervals and is used in combination with one or other of certain types of switches for rearranging the sections of the winding. A drum switch for interconnecting the coils is shown in Figs. 4 and 6 in which contact fingers mounted on rotary shafts 5 are lifted from and lowered' on to contacts on a four-sided drum 1 by means of a hand-wheel 20. The drum is loose on the shaft 2 and coupled thereto bv a spring 3. Cranks 7 on the shafts 5 are coupled by pins 8 which enter four holes in a loose' disc 12 and are attached by springs 9 to a four-armed plate 10 also loose on the shaft. 'This plate is oscillated by a pin 15 on a lever 16 which is pivoted at 17 and moved by a roller 18 in a cam groove 24 in a disc 19 rigid with the hand-wheel. The cranks 7 are normally prevented from rotation by a pawl 21 which engages one of them. When the handle is turned as at f, Fig. 6, the drum is held by the pressure of the fingers 6 and the spring 3 is stressed. The cam 24 moves the lever 16 so as to turn the plate 10 in the direction f<1> and stretch the springs 9 until one of the arms 10 raises the pawl 21 and allows the springs to rock the shafts 5 and raise the contacts 6. The spring 13 thereupon rotates the drum 1 and upon further movement of the hand-wheel and cam 24, the lever 16 and cranks 7 return to their original position with the contacts on the drum. In the switch shown in Fig. 8, a plate 104 with contacts on its underside is raised, rotated and lowered again to effect regrouping among contacts 103 fixed on a lower plate 101. The bottom of the stem 105 is carried by a pin 108 in slotted levers 110 which are pivoted to the framing at 111 and coupled by springs 114 to two levers 116 also pivoted to the frame. The levers 116 carry a roller 118 taking into a cam 119 on the operating shaft 120. Another cam 126 on the same shaft engages a roller 125 on a lever 123 which is linked at 122 to an arm 121 on the stem 105 for rotating it. When the shaft 120 is turned, the cam 119 raises the levers 116, 110 and stem 105 thereby opening the circuits and removing an anti-rotation roller 130, Fig. 9, on the top plate 104 from a positioning groove. The cam 126 then rocks the lever 123 and turns the plate 104 to give the new grouping when the roller 118 drops into the next groove in the cam 119 and the roller 130 into the next positioning groove. The plate 104 may alternatively be raised and turned directly by levers instead of by cams. Fig. 12 shows a form in which two plates 205 are, by means of a lever 207, moved away from fixed contacts 203, rotated and replaced. The plates are carried on shouldered tubes 213 sliding on the shaft 214 and are normally held by hooks 215. The lever 207 moves between cam surfaces, Fig. 15, formed on the flanges of tubes 208 which slide, against the action of springs 221, in bearings in the fixed contact supports 201. Rings 210 in the tubes 208 bear on the flanged ends of tubes 211 between which and the shouldered tubes 213 are compression springs 212. Arms 217 on t'he shaft 214 are coupled by springs 218 to the plates 205 for rotating them and notched plates 219 and rollers 220 give the plates 205 definite positions. When the lever 207 is rocked, the springs 218 are stressed and the outward movement of the flanged tubes 208 allows the tubes 211 to press on the contact plates 205 against the action of the hooks 215. When the ends of the tubes 208 deflect the hooks 215, the springs 212 move the plates 205 axially and, upon disengagement of the positioning rollers 220, they are turned by the springs 218. Entry of the lever 207 into the next cam notch allows the tubes 208 to move in and the new grouping of contacts 203 to be closed. Collars 216 allow wear of the contacts to be taken up.