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WWW WI POWER svsijéiv'l'é ' ' ' ‘135 Dec- 1'0, 1946. M. F. JONES ET AL 2,412,512 FEEDER SYSTEM FOR LINEAR MOTORS Filed Oct. 14, 1943 \\\\\\\\\\\ _ ‘ INVENTORS Mal/nae [Jo/re: 00a’ 7 lee A. ,‘f/(9ore. ATTORNEY g Y I V I “UUIH "wasn' GEM-ii bll l‘lUUl H POWER SYSTEM ‘1235' Patented Dec. 10, 1946 2,412,512‘ UNITED STATES PATENT OFFICE 2,412,512 FEEDER SYSTEM FOR LINEAR MOTORS Maurice F. Jones, Wilkinsburg, and Lee A. Kilgore, Forest Hills, Pa., assignors to West inghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 14, 1943, Serial No. 506,198 7 Claims. 1 Our invention relates to the polyphase feeder arrangement for the squirrel-cage track-member of a linear motor, and particularly a linear motor (Cl. 172-290) 2 metallurgical arts, the track-rails and the third rails would all be made of steel or other magnetiz able material which has a considerable impedance to the flow of alternating currents at 60 or 80 in which the movable element is the polyphase motored towing-car of an electric catapult for Cl cycles, which is the frequency-range at present launching aircraft, in the launching-arrange preferred. This impedance takes the form, not only of a high reactance because of the high mag netic ?uxes which traverse the magnetizable '1 '1 plication of Frank B. Powers, Serial No. 473,843, members, but particularly a very high resistance ?led January 28, 1943, and assigned to the West inghouse Electric & Manufacturing Company. 10 loss in the form of hysteresis and eddy-current losses. The general arrangement consists of a long Even aside from the use of magnetizable mate track-member having two track-rails, a lami rials for the track-rails and the third-rails, even nated squirrel-cage core between the two track though these rails were of low-impedance non rails, and a third-rail structure on each side of magnetizable material, the reactance of a three the two track-rails, and a polyphase-motored phase supply-system in which the phases were towing-car having wheels which run on the as widely separated as the two outside third-rail track-rails, a laminated polyphase-wound core structures, with the track-rails constituting the which cooperates with the squirrel-cage core of ;lment which is described and claimed in an ap intermediate phase, would be fairly high, and the track, and a current-collecting means for cooperating with the third-rail structure on each 20 the reactance between the two outside phases would not be the same as the reactance between side of the car, whereby two of the phases are ob the middle phase and either one of the two out side phase, so that there would be a problem of an undesirably high reactance and an unbal Preferably, the track-sections are made in sub stantialy completely prefabricated sections which 25 anced reactance. An object of our present invention, therefore, is are mounted on skids for easy installation, and to provide a three-phase feeder-system for an which are complete, with the third-rail structures electri?ed track of the type described, in which a carried by the track-structure, so that the track set of three three-phase feeder-conductors of sections are ready to be hauled into place, in a hollow trench dug in a ?ying-?eld, and ready for 30 non-magnetizable material is disposed along each side of the track. Phase-A of the feeder-group on service as soon as the track-sections are joined one side of the track is connected, at frequent together. The general structural design-fea intervals, to the third-rail structure at that side; tures of the linear-motor catapult, as just de another phase, such as phase-C of the other set of scribed, are described and claimed in an, applica tion of Maurice F. Jones, Serial No. 506,197, ?led 35 feeders, on other side of the track, is connected, tained from the two third-rail structures, while a third phase is obtained from the track-rails. October 14, 1943. Our present invention has to do particularly with the means for getting the three-phase power at frequent intervals, to the third-rail structure on that side of the track; and a plurality of sets of three three-phase non-magnetizable cross connectors are provided to extend under the track-rails and to join the corresponding phases of the two sets of feeder-conductors at a plural ity of spaced points along the track, with connec into the track-member, including the third-rail structures, and thence into the towing-car. It is quite desiralble that all three phases of the three~ phase power should be fairly well balanced, and tions from a third phase, such as phase-B of each that the impedance-losses in the feeder-system of the sets of cross-connectors to the track-rails should be reasonably low, because it is desirable, for safety reasons, to use a fairly low voltage of 45 of the track. A further object of our invention is to utilize, several hundred volts, which means the use of for each set of three three-phase feeder-conduc rather high currents which are necessary to ener tors, and for each set of three three-phase gize a towing-car of su?‘icient power to be of any cross-connectors, ?at strips of non-magnetizable practical use in aiding in the launching of air craft. In fact, the currents utilized are so high 50 material, with their ?at sides closely spaced from that they are very much higher than the highest each other, The close spacing of the strips con current ever heretofore collected for feeding into siderably reduces their reactance, while the use a moving car in any railway system. of conductors in the form of ?at strips, as dis In any practical construction, such as would tinguished from round-cross-sectioned cables, is ordinarily be built, in the present state of the 55 advantageous in making a compast three-phase 2,412,512 3 feeder-arrangement having a general overall cross-section approximating that of a circle, while maintaining broad-areaed, short, air-gaps be tween the several phases. While this ?at-strip construction is not essential, it is a desirable fea Cl ture of our invention, in its more speci?c aspects. Further objects of our invention relate to the various details of construction, such as utilizing laminated or ?exible non-magnetizable strip conductors for the feeder-phases which are con -As shown in Figs. 3 and 4, each of the core supporting cross-members I08 has a dovetailed groove I I0 cut in its upper surface, for making a dovetail joint with a plurality of vertical, longi tudinally extending magnetizable laminations which constitute a laminated core-member H2. The core-laminations H2 are clamped together, at each end of the stack of laminations, that is, along each side of the core, by means of one of 10 two angle-iron clamping-pieces I I3 which are se nected to the respective third-rail structures, cured to the top ?anges of the several cross-ties while utilizing solid-bar strips for the other feeder-phases, the ?exible construction ‘being ad clamping angle-pieces II3 thus constitute longi I04 which make up that track-section. The core tudinally extending members, extending longi vantageous in permitting the ?exible strip to readily buckle, as a result of thermal expansions 15 tudinally of the track, and rigidly joining to gether the various cross-ties I04 of each prefab and contractions, without buckling the third-rail ricated track-section. The laminated core II2 structure to which the ?exible strip is connected of each track-section has a plurality of trans at two 01' more points. As a practical detail, the versely extending slots I I4 therein, which receive various sets of three-phase cross-connectors which are disposed underneath the track-rails are 20 squirrel-cage bars II5, the ends of which are joined, on each side of the core, by suitable end made of three flat strip-conductors disposed one connections I23. above the other, with the top and bottom con At each end of each of the track-sections, as ductors transposed, at some point intermediate shown on the right-hand side of Fig, 3, a ?exible between the track-rails, and with the central con ductor connected to the two track-rails. 25 electrical connector I36 is provided, for continu ing the end-connections of the squirrel-cage With the foregoing and other objects in view, winding from one track-section to the next. The our invention consists in the combinations, sys flexible end-connections I36 are provided with tems, methods, apparatus and parts, hereinafter holes I3‘I for bolting on to the corresponding end described and claimed, and illustrated in the ac companying drawing, wherein 30 connector of the next track-section. Each track-section TI, T2, etc., also carries, as Figure l is a longitudinal plan-view of a por tion of a landing or launching ?eld, with our linear-motor catapult installed, a prefabricated part thereof, a plurality of in~ sulatedly mounted third-rail structures, one on each side of the track, outside of the respective Fig. 2 is a side view thereof, showing the track element of the linear motor, installed in a trench 35 track-rails I06. In the illustrated form of the invention, each third-rail structure is in the form or shallow ditch dug in the ?ying-?eld, of two angle-iron rails I4 I, having vertical ?anges Fig. 3 is an end View of the linear-motor, in I42 which are spaced from each other, and hav cluding both the car-element and the track ele ing top~?anges I43 which extend out away from ment in a trough in the ?ying-?eld, with half of the equipment shown in transverse section, as 40 the space between the two vertical ?anges I 42. The pair of third-rails I4I, on each side of the indicated by the section-line III-III in Fig. 1, track-structure, is mounted on a plurality of U Fig. 4 is a plan view of a part of a track-section, shaped supporting-brackets I44, which are sup with parts broken away to show the construc ported on insulators I45 which are, in turn, sup tion, and Fig_ 5 is a detail of one of the sets of three 45 ported from the cross-ties I04 of the track three-phase feeders, showing the laminated feeder-phase which is connected to the adjacent third-rail structure. As shown in Figs. 1 and 2, the track-element is section. laid in a shallow ditch or trough IOI, in a land the ends of which are turned up, as indicated at ing-?eld or launching-?eld, so that the top of the track will come approximately flush with the surface of the landing-?eld. The track-element, as illustrated, is made up in the form of a plu I48, to facilitate hauling the various track~sec tions into place on the landing-?eld. The chan In the illustrated form of embodiment of the invention, the cross-ties I04 of each track-sec tion are mounted on channel-sectioned skids I41, nel-member ‘skids I 41 also constitute a conven ient abutment for the lower ends of the third rality of at least partially prefabricated track 55 rail insulators I45, which are shown, in Fig. 3, as being mounted on plates I49 secured within sections TI, T2, T3, etc., said track-sections hav the channel-member skids I41, thus being sup ing squared-off abutting ends which are joined ported from the bottoms of the cross-ties I04, together in a straight, line. The movable element to which the skids are connected. of the linear motor is a low, ?at, elongated, poly phase-motored towing-car I03, which rides on 60 In accordance with our invention, each track section has two sets of three three-phase feeder the track-element. conductors FA, FE and FC, extending the entire As shown in Figs. 2 and 3, each track-section length of the track-section, a complete set of TI, T2, etc., comprises a plurality of cross-ties three feeders being disposed along each side of I04, which are shown in the form of steel H beams. The top ?ange of each cross-tie I04 has 65 the track-section, outside of the respective third rail structures I4I. Preferably, the feeder-con two track-rail seats I05, for receiving the two ductors FA, FE and PC are ?at, vertically dis track-rails I06, respectively. Preferably, the posed strips of copper or other non-magnetizable track-rail seats I05 are bordered, on the outside, conductors, having their ?at sides closely spaced by abutments I01 which are carried by the cross ties for determining the alignment or spacing of from each other, in order to reduce the reactance. the track-rails I06. Between the two track-rail The extreme ends of the feeders FA, FE and FC seats I05, each cross-tie I04 carries a core-sup of each track-section may be bent out a little porting cross-member I08, which is mounted on further apart from each other, in order to facili the top of the cross-tie, as by means of support tate the making of electrical end-connections ing-blocks I09. 75 from one track-section to the next. m 4 ). “ ?owan was ' 135 ‘2,412,512 5 seat I05 and the abutment I01 at the top of the cross-tie I04. This provides a simple and effec tive fastening-means whereby the track-rails I 06 The phase-conductor FA of the three-phase feeder-assembly FA, FE and FC on one side of the track-section is disposed adjacent to the outer rail I4I of the third-rail assembly on that side of the track-section, and is electrically and me chanically secured thereto, at a plurality of points, as by being bolted by the same bolts or screws I50 which secure the U-shaped support ing-brackets I44 to the third-rails I4I. On the may be quickly fastened into place, with a mini mum of lost motion, when the track-sections are assembled in the ?eld. As shown in Fig. 3, each track-section is also provided with lateral guard-members I6I which are carried by the track-section supporting other side of the track-section, another phase, 10 structure, as, for example, by the two skid-mem bers 141, for guarding the track-section while it indicated by the phase-conductor PC of the is being put into place within its trough IOI in feeder-assembly FA, FE and FC, is disposed ad the ?ying-?eld, and also to prevent dirt and jacent to its corresponding outer third-rail I 4|, rubble from falling into the track-section from and similarly secured thereto at a, plurality of the sides of the trough. The two guard-mem points. bers I6I have inwarly turned top-flanges I62 At a plurality of points along the entire track, which are substantially ?ush with the top of the preferably once for each of the track-sections TI, ?ying-?eld. T2, T3, etc., a set of three three-phase cross-con The top surfaces of all of the parts of the en nectors I5I, I52 and I53 are disposed underneath tire track-structure are preferably substantially the track-rails I 06 and the track-core II2 for flush with the level of the ?ying-?eld. The tops connecting the corresponding phases of the two horizontal, and lying one above the other in of the two third-rails I4I of each of the third rail assemblies, four rails in all, are preferably covered and protected by wooden or other insu lating cap-strips I63, the tops of which are ap proximately ?ush with the landing-?eld. The tops of the track-rails I06 are also preferably closely spaced relation, except that the top and approximately flush with the landing-?eld. The feeder-assemblies FA, FE and F0 on the two sides of the track. Preferably, each set of three three-phase cross-connectors I5I, I52 and I53 consists of ?at strips of non-magnetizable con ducting material, disposed with their ?at sides top of the squirrel-cage core “.2 is also approxi bottom conductors I5I and I53 are transposed, somewhere in the center of the track-section, so 30 mately ?ush or level with the flying-?eld, but preferably very slightly higher than the ?ying that they may be conveniently connected to the inner and outer phase-conductors of the two sets ?eld, as indicated in Fig. 3. Preferably, also, two wooden beams or other of feeders FA, FE and F0 on the two sides of the insulating ?llers I64 are utilized, to partially track-section. The intermediate cross-connector fill the space between the end of the squirrel I52, which is connected to the two intermediate cage winding and the inner sides of the rail-heads phase-conductors FB of the two sets of feeders, of the two track-rails I06, in each track-section. is centrally connected, by means of a strip-con Since the track-core H2 is very slightly higher ductor I54, to the bottom ?ange of one of the than the level of the rail I06, the top surface cross-ties I04, and thence to the two track-rails of the wooden block I64 may be slightly inclined, I06 which are supported by the top ?ange of said as indicated at I65. cross-tie. As shown in Fig. 5, we prefer to utilize a spe The ends of the track-sections TI, T2, etc., are squared off, as shown at 166 in Figs. 1 and 4, and cial construction for the feeder-conductor which aligned by means of dowel-pin joints I61, as is disposed adjacent, and connected at frequent points, to the outer third-rail I4l on that side of 45 shown in Fig. 3, the successive sections being tightly drawn together by means of turnbuckles the track-section. We refer to the feeder-phase I68 which engage notches not shown which are FA on one side of the track, and the feeder phase cut in the‘bottom ?anges of the core-clamping F0 on the other side. As shown in Fig. 5, the feeder-phase which is connected to the third-rail angle-irons II3 of the frame-structures of the is made of a laminated strip-construction, as 50 several track-sections. The towing-car I03, which rides on the track shown at I55 in Fig. 5, or otherwise composed of a plurality of pieces of thin conductors, whereby element of the linear motor, as shown in Figs. said strips are relatively ?exible, so as to prevent 1, 2 and 3, comprises a long ?at top-plate I1I ‘bending the associated third-rail when said ?ex which is provided with a large number of lateral ible feeder-strip expands and contracts as a re notches I12 for receiving a large number of sult of heating because of the electric current wheels I13. It is also provided with a number ?owing therein. The remaining phases of the of pairs of holes I14, between which is machined, feeder-strips FA, FE and FC, on both sides of the on the underside, a number of transversely ex track, are of solid-bar construction, of a good tending dovetail grooves I15 for making a clove conducting, non-magnetic material such as 60 tail joint with a large number of vertical, 1on copper. gitudinally extending laminations or magnetiz A special rail-fastening means is shown, in Fig. able core-punchings I11 which make up the pri 3, for securing the two track-rails or running_ mary-winding core I11 of the linear motor. The rails I06 to the several cross-ties I04, with the stack of laminations I11 of the primary-winding outer edges of the bottom ?anges of the rails in 65 core are clamped in place by means of two, lon contact with the rail-aligning abutments I01. gitudinally extending angle-irons I18 which are This special rail-fastening means includes a. plate-like member I38 having one edge which is secured to the underside of the top-plate I1I. engageable at the junction between the rail-web and the base~?ange of the rail, at the side of each track-rail opposite to the side which is engaged by said abutment I01. The plate-like member of the top-plate I1I, on the underside of said plate, are two side-pieces I80 carrying inwardly Extending longitudinally along the lateral edges 70 extending stub-shafts I84 on which the car wheels I13 are journalled. The car wheels I13 are disposed, at frequent I38 is'drawn down tightly toward the cross-tie intervals, along the length of the car I03, and I04 by means of a bolt or screw I 39, which forces the rail into tight engagement with both the rail 75 are provided with broad rims which roll on the 2,412,512 8 comprising a pair of track-rails, a set of three tops of the track-rails I06. Most of the wheels are un?anged, but the four wheels at the front three-phase feeder-conductors disposed along and rear of the car are provided with ?anges I85, each side of the track, a plurality of sets of three which, contrary to usual railway practice, are three-phase cross-connectors extending under the track-rails and joining the corresponding on the outside of these guide-wheels, so as to en. gage the outer edges of the rail-heads of the track-rails I 06. The primary core I" which is carried by the phases of the two sets of feeder-conductors at a plurality of spaced points along the track, con nections between a ?rst phase of each of said sets of cross-connectors and the track-rails of 10 the track, a three-phase motored car operative ing I90, which is shown in Fig. 3, on said track-rails and deriving one phase of its The towing-car I03 is also provided with two electrical energy from said track-rails, a current current-collecting mechanisms, enclosed in hous collecting means on one side of the car for deriv ings I9I disposed one on each side of the car. ing a second phase of its electrical energy from Each of the current-collecting mechanisms com the corresponding phase of the set of feeder-con prises a plurality of third-rail shoes I92 which ductors on that side of the track, and a second are carried ‘by the downwardly extending plows current-collecting means on the other side of or support-members I93 which extend through the car for deriving a third phase of the set of slots between the pair of cap-strips I03 at each feeder-conductors on that side of the track. side of the track, so that the two sets of third 2. The invention as de?ned in claim 1, char rail shoes I92, on the two sides of I the car I03, 20 acterized by each set of feeder-conductors com engage the two pairs of third-rails MI, one pair prising three ?at strips of non-magnetizable con on each side of the track. In this manner, two car is provided with a three-phase primary wind of the phases of the three-phase supply are led into the primary windings I90 of the car, the third phase being obtained from the track-rails _, I06 in a manner which is common railway prac tice. The special collector-shoe design, which Was developed for the purpose of handling the ducting-material with the ?at sides of successive strips closely spaced from each other. 3. The invention as de?ned in claim 1, char acterized by each set of feeder-conductors and each set of cross-connectors comprising three ?at strips of non-magnetizable conducting-material with the ?at sides of successive strips closely unprecedently high currents which had to be col lected, constitutes the subject-matter of an ap 30 spaced from each other. 4. The invention as de?ned in claim 1, char plication of Maurice F. Jones, Serial No. 506,199, acterized by each set of feeder-conductors and ?led October 14, 1943. . each set of cross-connectors comprising three ?at The precise arrangement of the three-phase strips of non-magnetizable conducting-material cross-connectors I5I, I52 and I53, under the track-rails I05 and the track-core H2, is shown 35 with the ?at sides of successive strips closely spaced from each other, the three strips of each more clearly in Fig. 4, wherein it is seen that set of cross-connectors being disposed one above these cross-connectors are made in subdivided another, the upper and lower cross-connectors parts, joined together under the middle of the being transposed at some intermediate point, the track-section. Thus, the phase-A cross-connec tor I5I appears at the top, as it comes from one 40 phase which is connected to the track-rails being the middle strip of both of the sets of feeder side of the track, and at the bottom of the group conductors and all of the sets of cross-connec of cross-connectors coming from the other side tors. of the track, the two phase-A track-connectors 5. A three-phase system comprising a track I 5| being joined together, at the longitudinal center-line of the track-section, as indicated at 45 comprising a pair of relatively high-impedance track-rails, a relatively high-impedance third 200. A similar joint 202 is made at the longi rail structure on each side of the track, a three tudinal center of the track-section between the phase~motored car operative on said track-rails two phase-C cross-connectors I 53, which come and having current-collecting means engaging from the bottom of the stack of cross-connectors, on one side of the stack, and the top of the stack 50 said third-rail structures, a set of three three phase feeder-conductors of non-magnetizable of cross-connectors, on the other side of the conducting-material disposed alongside of each track, as plainly shown in plan view in Fig. 4. third~rai1 structure, one set of feeder-conductors At the center where the joints 200 and 202 are having one phase thereof connected to its associ made, the two phases A and C of the cross-con ated third-rail structure, the other set of feeder nectors I5I and I53 are displaced out of vertical conductors having a second phase thereof con alignment with each other. The two interme nected to its associated third-rail structure on diate, or phase-B, cross-connectors I52 are bent the other side of the track, a plurality of sets of out of the vertical plane of the stack of cross three three-phase cross-connectors extending connectors, near the center of the track-section, as indicated at 203 and 204, and these two ends 60 under the track-rails and joining the correspond ing phases of the two sets of feeder-conductors are joined by a short conductor 205 which is, in at a plurality of spaced points along the track, turn, joined, by the previously mentioned con and connections between the third phase of each ductor I54, to the bottom ?ange of one of the of said sets of cross-connectors and the track cross-ties I04. rails of the track. While we have illustrated our invention in but 6. A track-element of a polyphase linear motor, a single form of embodiment, we desire it to be understood that this embodiment is only by way comprising a. plurality of at least partially prefab of illustration, and that our invention, in its ricated track-sections, each track-section com prising a supporting-structure squared at the ends for abutting with the next track-section, broader aspects, is susceptible of many changes by way of addition, simpli?cation, and substi tution of equivalents. We desire, therefore, that our appended claims shall be accorded the broad est construction consistent with their language. We claim as our invention: means for aligning and drawing together the abutting track-sections, said supporting-struc ture of each track-section comprising a plurality of cross-ties, said cross-ties having means for 1. A three-phase system comprising a track 75 seating and aligning two track-rails, a third-rail I, III'II" searcn mom‘ POWER SYSTEMS v1 3.5L. 2,412,512 10 section having a laminated squirrel-cage core structure at each side of each track-section, out side of the track-rails, insulators for supporting structure connected to said cross-ties between said third-rail structures from said supporting the track-rails, a relatively high-impedance structure, a plurality of other phase-conductors third-rail structure at each side of each track alongside of each third-rail structure at each 5 section, outside of the track-rails, insulators for side of each track-section,po1yphase electric consupporting said third-rail structures from said nection-means between successive track-sections supporting-structure, a set of polyphase non for the third-rail structure and the other phasemagnetizable feeder-conductors alongside of each conductors on each side of the track-element, third-rail structure at each side of each track each of a plurality of said track-sections having 10 section, one set of feeder-conductors having one polyphase cross-connectors extending under the phase thereof connected to its associated third track-rails and joining corresponding phases of rail structure, the other set of feeder-conductors the third-rail structures and the other phasehaving a second phase thereof connected to its conductors on opposite sides of the track, the associated third-rail structure on the other side third-rail structures being of two different phases, 15 0f the track-section, polyphase electric connec and connecting-means between a third phase of tion-means between successive track-sections for said cross-connectors and a track-rail. 7; A linear motor comprising a squirrel-cage track-element and a polyphase-motored car 00- the feeder conductors on each side of the track element, each of a plurality of said track-sections having polyphase non-magnetizable cross-con operating therewith; said track-element compris- 20 nectors extending under the track-rails and join ing a plurality of at least partially prefabricated ing corresponding phases of the feeder-conductors ' track-sections, a pair of relatively high-imped- on opposite sides of the track-section, and con ance track-rails therefor, each track-section necting-means between a third phase of said comprising a supporting-structure squared at the cross-connectors and a track-rail; said car hav ends for abutting with the next track-section, 25 ing a laminated polyphase-wound core-structure means for aligning and drawing together the in cooperative relation to said squirrel-cage core abutting track-sections, said supporting-struc- structure, and current-collecting means engaging ture of each track-section comprising a plurality said third-rail structures. of cross-ties, said cross-ties having means for MAURICE F. JONES. seating and aligning two track—rails, each track- 30 LE A. KILGORE.