US2305686A - Electromagnetic core - Google Patents

Description

Dec. 22, 1942.

l/v vE/vron I E. E. FRN Bv jnqwlam.

, Arron/ver I been encountered.

Patented Dec. 22, 1942 Erwin E. Franz, Cranford,

Western Electric Company,

N. J., assignmto Incorporated, New

York, N vY., a corporation of New York Original application December 9, 1938, Serial No.

244,729.' Divided 1940, Serial No. 338,060

2 Claims. .(Cl. 175-.21)

This invention relates to electromagnetic laminated cores assembled from sheet metal elements. Coils are used in -an endless variety of forms and Ways in electrical' apparatus, and generally.-

speaking fall into two great classes, coreless coils and cored coils in which the windings surround cores of magnetic material. Cored coils very frequently are made with cores built up from assembled laminae of sheet material, in order to diminish energy waste due to eddy currents in the body of the core. Much ingenuity has been expended upon ways of manufacturing such laminated cores in order that the making of the cores and the assembling of the cores and their windings may be as simple, cheap and wasteless as possible. For various reasons difculties have Coils have been produced satisfactorily with cores which are wasteless in production, but with which the winding must be prewound on a spool or other support and then installed bodilyupon the assembled or partly assembled core. In sur-.h structures space is taken up and wasted so far as the efficiency of the coil is concerned by thespool or support on which the coil is wound. Other laminated core coils have been produced in which the winding of the conductor has been done directly on the assembled or partly assembled core without the needof any special Winding spool or frame. Howevenin many instances the laminae for assembling such cores cannot be produced wastelessly. Furthermore, in cases where the core` is assembled in a prewound Winding, the `mechanical working ofI the laminar core material when the laminae are clamped or riveted together may seriously damage the magnetic properties of a core Vmade of v some of the recent high permeability allo-ys; and such.cores cannot be then annealed to restorefthe desired properties with the insulated windings in place on them. f Y

An object of the present invention is to provide a coil structure and a laminated core for a coil which shall present a coil having a core and winding combinable substantially without any electrically useless winding spool, frameor the like, iny which the laminar core is composed of" elements produced from sheet material in which a considerable range of ratiorof windingvolumeto core is possible, which is adaptable equally to such constructions as shell type andcore 'type transformers among/others and in which the a parallel sided posite ends of the crossbar of the H and rela-` and this application May 31,

typical-embodiment of the invention may comprise a coil having a core built up of layers, each layer consisting of two equally tall flat pieces punched or otherwise formed from magnetic sheet material, of which pieces each outer one may be L-shaped and the middle piece an H lying on its side and having long arms extending oppositely from opposite ends of its crossbar to abutthe armless sends of the two Ls and short arms respectively in line with its long arms and on opposite sides of the crossbar to abut the ends of the arms of the two Ls.

Other objects and features of the invention will l appearfrom the following detailed description of an embodiment thereof takenin connection with the accompanying drawing in whichthe same reference numerals are applied to identical parts in the several figures and in which- Fig. l is a diagrammatic view of a strip of magnetic sheet material to show the wasteless production of core lamina parts therefrom;

Fig. 2 is a pla View of a core composed of the laminar parts of Fig. l;

y Fig. 3 is an enlarged sectional view on 3-3 of Fig. 2; and i Fig. 4 is a plan view of a coil wound on the core shown in Fig. 2.

Fig. 1 may be thought netic-lsheet material from whichlaminar pieces are to be cutior subsequent assembly intounits of anelectrical coil core, and on which the pieces are laid out to show how they may be cut from the line or Waste. There are two kinds of pieces shown, viz. L-shaped pices indicated at 20 having arms 2l and H shaped pieces indicated at 24 having relatively long arms 25 on opposite sides and op- 21 in line. with and opposite to tively short arms The Lv-shaped pieces have holes the long arms.

y 26; through which assembling rivets '30 are to be core is so constructed that no Working of the core material is 'required'after the windingsare in* stalled.

With the above and other objects view,a 55

passed later. The H-shaped pieces have similar holes26.A f e "In cutting the various pieces, of 'which there are only two kinds, as shown `in Fig. l, a set ot four perforations 26 is first punched in the strip or ribbon at an operating station indicated at I. At station II an L-Shaped piece 2|.'l is punched of as a ribbon of magribbon substantially without scrap out., At'station-III a second L-shaped piece 20 is punched out,` and at station-IV thev H-shaped piece`24 is cut off'.

The two Lashaped pieces are identically alike and interchangeable in assembly. Each is formed and proportioned toxhave the' notched top of its long arm abut and nt accurately into notch 35 ing to the invention, no

' straining oi' the material of of either long arm 33 of the H-shaped pieces while its short arm extends into and tits the notch 3l ol' the short arm o1' the H on the same side.

The two kinds of pieces shown in Fig. 1 having been preparedv in suilicient number, are assembled by stacking and riveting into the three units .shown in Fig. 2 at 3l,

with the crossbars in supr'erimposeriL congruence and the long and short arms extending alternately to the left and right.' This stack or unit 32 has all of its surfaces substantially smooth except the four extremities of its arms, which are recessed to correspond on one side to the projections between the recesses of the arms of 'the unit 3i and on the other to those of thej unit 33.

The threeistacks havhig been piled as described independently of each other, may be riveted, rcspectively, with' rivets 3d, or otherwise bound t0 form rigid units.

The material ci the core pieces and 24 in some instances will preferably beof silicon steel or oi? one oi.' nickel iron alloys known as `l'iverniallor` materials may be given an extremely high` per= meability, or retentivity. or low hysteresis, or other desirable electromagnetic character by appropriate heat treatment. These materials, however, are extremely sensitive to mechanical working, or even shock, ai'ter treated; and any These that the alternations are the L-shaped pieces 23, ,l

another of the high permeability mum symmetry impairthe particular characteristic of the ma-f terial. A

In employing the v,the heat treatment units 3l, 32 described, i.

.present invention therefor, is deferred until the three and 33 are individually complete as e. stacked and riveted, since, accordoccur.

To make such a coil as is shown in Fig. 4, it is then onlyfnecessa'ry to wind the unit 33 and assemble the three. umts. .The winding Space/between the arms of the H-haped unit 32 is completely unobstructed. The winding oi' the insuto have tlie relations to the Figs. 2 and 3.

36, consists essentially oi successive layers; each layer consisting of' one H further working orthe cores need then on a spool, frame orothci:

, tical faces of stantially smooth planebut is a square angled -Zlgzag with elements o1' one unit overlapping elements of the other by an amountequal to twiceA the area of a notch 33. This zigzag overlapping at the joints brings two desirable results. First, the gap reluctance of the assembled cores magnetic paths at the jointel oi? the units is materially corresponding joint is a plane face and there is no lateral. contact between parts of the units. Secondly, the interiltting oi the projections and recesses oi the units provides a modicum of mechanical support o1' the units by each' other and. of frictional resistance to separation oi' the units, which renders the assembled. ycore or coil mucI/.i easier to handle and mount. due regard being had to the sensitivity of the .material to shock or deformation.

it is also of importance that the H-shaped unit 32 cuers no obstruction to the winding or the turns 343.. Hence 'the coil need noi'. prewouhi support for Subscn quent assemblyV4 with a core unit, as is the case, for example, with a coli core generally similar to that oi' Figs. l to i but composed of E-sha1per pieces with a straight bar across the open side of each E. Hence, as clearly shown in Fig. the yentire cross section ci each of the apertures or windows of the core is available to be illlez with windings, be wasted either to receive an electromagnetically inoperative winding spool dr frame, or by clearance oversize internally and undersize external." ly ci a prewound' coil formed with adhesive or other means to maintain its form while being as" sembled on the core.

The core shown in Figs. l to Athan, the maxi in all ways possible to this mode The windows are square, the the` same shape and size as the and each side of a window not made .by the crossbar is the same size and lshape as half. the crossbar or window. The core cross section or the magnetic path is the same throughout, as suming that the iiux divides equally on leaving the crossbar to pass around the two windows.

In another l variation oi the invention, smooth butt joints between the units 3|, 32 and 33 oi' Fig. 2 be desired, the units 3i and 33 may be composed of L-shaped pieces stacked in con gruence and the Hs in unit 32 may be stacked with their long arms all in congruence. The ver Vthe ends of the arms of all three units will then be substantially smooth and the units maythen be abutted without interiltting. Such a structure with coils on ali three could then be used wherever variable inductive coupling between coils isdesired by separating or approximating the wound units.

The general structure for a laminated core coil which is wasteless in construction and which o'bviates anyV need for preformed or pwound o! construction.

, windings isnot claimed herein, being the general shaped piece and two similar L-shapw. pieces.

Thegtop layer has the L at the left rightside upas'shown, and the L at ther-ight upside down. The second layer has identically similar elements but in reverse symmetry. Every odd numbered layer is identically like the first, and every even like the second. From'this it follows that the division between the units 3| and 33V or between the units 32 'and 33 is not a nub- 75 cl subject matter oi' copending application Serial No. 244,729, lled December 9, 1938, by the present inventor, upon which appl cation U. S. Pat ent No. 2,235,425' was granted on March 18, 194i and of whichthe present application is a divi' sion. i

The embodiments o1' the invention herein disclosed are illustrative and may be modified and departed from in many ways without departing from the spirit and scope of the invention as pointed outin and limited solely by the appended ed as compared with a core where the f as none oi the window space need y What is claimed is: 1. In a laminated electromagnetic core, a lam;

ina consisting of an L-shaped piece and an H- to form a substantially complete v,

pietely and project outside the same when so fitted, the area of the parallelogram being sub- .stantially twice the area of the said space.

2. In a laminated electromagnetic core, a lamina consisting of an L-shaped piece and an -H- shaped piece and an L-shaped piece abutted together edgewise in that order, the two L-shaped pieces being so shaped and dimensioned as to be ttable together to form a substantially complete parallelgram which is itself fittable substantially without looseness into the space between the two arms or the H-shaped piece on the same side of the crossbar thereof, together with the correspending adjacent space Iof another H-shaped piece placed arm end to arm end beside the first named H-shaped piece.

ERWIN E. FRANZ.

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