US3378800A - Electromagnetic winding having coil wrapper with window insulating flaps - Google Patents

Description

PFE 16, 1968E A. J. LIBERMAN v 3,378,800

LECTROMAGNETIC WINDING HAVING COIL WRAPPER WITH WINDOW INSULATING FLAPS l 5 Sheets-Sheet l Filed, Jan. 25 1967 JMW@ April 16, 1968 A. J. LIBERMAN 3,378,300

` ELECTROMAGNETIC WINDING HAVING COIL WRAPPER WITH WINDOW NSULATING FLAPS 5 Sheets-Sheet L,

Filed Jan. 25, 1967 April 16, 1968 A. J. LIBERMAN 3,378,800

ELECTROMAGNETIC WINDING HAVING COIL WRAPPER WITH WINDOW INSULATING FLAPS Filed Jan. 25, 1967 Sheets-Sheet ."5

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United States Patent O 3,378,800 ELECTROMAGNETIC WINDING HAVING Cil.. WRAPPER WITH WINDOW INSULA'IlNG FLAPS Arnold J. Liberman, Skokie, Ill., assignor, by mesne assignments, to Electric Products Manufacturing Co., Beliwood, Ill., a corporation of Delaware Filed Jan. 25, 1967, Ser. No. 611,595 10 Claims. (Cl. 336-192) ABSTRACT F THE BESCLGSURE A circumferential wrapper for a transformer cc-il has aps extending from its side edges. The flaps are tucked into the coil window to insulate same. Tabs on the flaps provide complete coverage of all four inner faces of the Window. Extended portions of the tabs protect those of the inner coil edges which are not overlain by the flaps.

- Specification This invention relates to an improved coil wrapper for use lwith transformer or reactor coils and is particularly suitable for coils having an axial length greater than the Window width, and relates to the winding or wrapped coil itself.

Transformer and reactor coils are mounted on square or rectangular core legs; hence they are Wound with a square or rectangular window to receive the core leg. The innermost convolutions of the coil must be insulated from the core. Sometimes this is accomplished by winding the coil on a tube of cardboard or other insulating materail having a square or rectangular cross section. In other instances, a tube lof cardboard or other insulating material may be inserted after the coil is wound.

It has been proposed in Goad Patent No. 1,797,768 and Henderson Patent No. 2,749,525 to provide a wrapper which overlies the end face of the coil, and instead of cutting a square opening which overlies the coil Window, to make cuts in such a 4manner that iiaps will be provided which can extend into the Window for insulating purposes. However, 'these proposals have been made for fiat coils, and the arrangement sho-wn is not sui-table for a coil where the length is equal to or greater than the window width. Furthermore, the arrangement does not provide a wrapper for all four outer faces of the coil, that is, it does not provide a circumferential wrapper.

According to my invention, I provide a wrapper for the four outer faces of the coil which is in the form of an elongate member of insulating material, such as coated paper stock having a length somewhat greater than the circumference of the coil. Then along each side edge of the elongate member I provide two tiaps which can be folded inwardly into the window to provide the window insulation. The flaps have tabs which insulate adjacent inner faces of the window. By thus providing the iiaps along the edge of a circumferential wrapper, the wrapper design is not as limited as in former arrangements, and in particular I provide with a single blank both a circumferential wrapper and Window insulation for all four inner faces.

My invention provides other advantages in that portions of the end faces of the coil are also covered, and the inner coil edge of the uncovered portions are protected by iiap extensions which project beyond the end faces.

Also, according to my invention, the wrapper may also serve as a terminal mount or boar-d.

Other objects, features, and adavntages will become apparent as the description proceeds.

With reference now to the drawings in which like reference numerals designate like parts:

ICS

FIG. l is an end View of a coil embodying my invention;

FIG. 2 is a side View;

FIG. 3 is atop view;

FIG. 4 is a vertical section taken along line 4-4 of FIG. 3;

FIG. 5 is a plan section taken along line 5-5 of FIG. l;

FIG. 6 is a perspective view of a partially folded wrapper illustrating the operation;

IFIG. 7 is a plan View of the unfolded wrapper or blank;

FIG. 8 is a plan View of a modified Wrapper;

FIG. 9 is a section taken along line 9-9 of FIG. 8;

FIG. l0 is a perspective view of an unwrapped coil;

FIG. ll is a plan view similar to FIG. 5, but of an unwrapped coil;

FIG. 12 is a view similar to FIG. 7, but showing a modified arrangement;

FIGS. 10 and ll show an unwrapped coil 10 having Ithe axial length L made up of layers 11 of wire or alternate layers of wire and paper. The coil has a rsquare or rectangular window 12 of width W. As shown in FIG. l, the shape of the coil is maintained during handling by a strip of adhesive tape 13 which surrounds one portion.

As shown in FIG. l0, lthe coil has four outer vfaces 14, four inner faces 15a, 15b, 15C, 15d, and end faces 16. The end lface 16 can be considered as being made up of four rectangular portions, 16a, 16b, 16e, 16d, plus corner portions 17. Where the end face intersects the inner faces, the inner edge is designated by the reference numeral 18. The wire convolution which occupies the inner edge position is particularly vulnerable to nicking in the course of handling, and inserting the core leg. Therefore, in addition to providing insulation `for the inner faces 15, it is desirable to provide some mechanical protection for the inner edge 1S.

As shown in FIG. 7, the wrapper or blank 20 comprises an elongate body portion 21 and four fiaps 22, two flaps being located along each side edge of the elongate portion 21. The liaps 22 are connected to the body portion by connecting portions 23. Each flap is divided into three parts, comprising a rnid part 24 and tabs 25. Score lines 26- are provided to facilitate folding.

As shown in FIGS. l to 4i, the elongate body portion 21 is wrapped around and overlies all four outer faces I4, and is secured in place by a strip of adhesive tape 27.

The flaps are then folded downwardly and inwardly into the window 12 so that the connecting portions 23 overlie the end faces lob and 16d. The mid parts 24 of the flaps overlie inner faces 15b and 15d, and the "tabs 25 overlie inner faces 15a and 15C.

The tab edges 25 may be rounded sufficiently to facilitate entrance into the window 12. The longitudinal dimension X of the mid part 24 (i.e. the dimension running longitudinally of the blank 20) is substantially the same as the width W of the window 12. The transverse dirnension Y of the mid part 24 is more than half the axial length of the coil. As shown in FIG. 1l, the inner face 15 may be divided into two end halves 28, and each end half may be considered as being made up of two end quarters 29. Thus it will be seen that the dimensions are such that the mid part 24 will completely overlie an end half 28, and the opposite mid part will completely overlie the other end half 28, and there will be some overlapping so that the inner face 15 is completely covered by the two mid parts 24, as shown in FIG. 5.

Each tab 25 overlies ya complete end quarter, as shown in FIG. 5. Thus in the case of end face 15a, it will be completely covered by the four tabs which overlap each other.

As shown in FIG. 7, there are L-shaped cuts so that the connecting portion 23 will be of a greater width than the mid part 24. The advantage of this arrangement is that the connecting portion 23, as shown in FIG. 1, extends partially into the corner portions 17 of the winding, giving greater protection to the end face of the coil. Also, a portion 31 of the tabs 25 extend axially from the coil as shown in FIGS. 2 and 3, and thus provide mechanical protection for the inner edges 18b and 18d, the inner edges 18a and 18C being protected by the overlying connecting portions 23.

Thus, mechanical protection is provided for all four of the inner edges 18.

The extended portions 31 may also serve as spacer members to space adjacent coils from each other by a predetermined distance. This coil spacing is necessary in the case of leakage reactance transformers and ballasts for fluorescent lamps and other gaseous discharge devices.

Instead of having the aps 22 located opposite to each other as shown in FIG. 7, it is possible to stagger them as shown in FIG. 12 so that there is one mid part for each inner face 15. Here the different mid parts are designated by the letters A, B, C and D, corresponding to the inner faces overlain by each. One end half of each inner face 15| is covered by a mid part 24, and the other end is covered by the two tabs 25. In FIG. 7, the oppositely disposed mid parts completely overlie the faces 15b and 15d, whereas the inner faces 15a1 and 15C are completely covered by the inner tabs as shown in FIG. 5.

A further modification is shown in FIGS. 8 and 9 in which the end part 32 of the elongate body portion 21 which overlaps the other end, has stapled to it by staplesl 33 two insulated coil leads 34. The coil ends 35, as shown in FIGS. 1 and 2, may thus be soldered to the bared ends of the insulated leads 34, the wrapper part 32 thus serving as a terminal board which provides the desired strain relief for the coil leads A34.

A particularly suitable material for the wrapper is a non woven nylon librous product sold under the Du Pont trademark Nomex.

Although preferred embodiments of the present invention have been described herein, it will be understood that various modifications and changes may be made in the construction shown without departing from the scope of the invention as pointed out in the appended claims.

I claim:

1. An electromagnetic winding comprising a coil having four outer faces, a window providing four inner faces, and two end faces each having four rectangular portions and-four corner portions, and a wrapper for said coil, wherein said wrapper comprises an elongate body portion overlying said four outer faces, said elongate body portion having two flaps extending from each side thereof, each flap having a mid portion overlying the end half of one inner face and two tabs overlying the adjacent end quarters of adjacent inner faces, and a connecting portion disposed between each flap and said elongate body portion and overlying one of said four rectangular portions of said end face.

2. An electromagnetic winding as claimed in claim 1 in which each tab has a portion extending outwardly of said window beyond said end face.

3. An electromagnetic Winding as claimed in claim 1 in which said connecting portion has a dimension greater than the width of said window to cover at least a portion of one of said corner portions of said end face.

4. An electromagnetic winding as claimed in claim 1 in which each tab has a portion extending outwardly of said window beyond said end face, said connecting portion having a dimension greater than the width of said window to cover at least a part of one of said corner portions of said end face.

5. An electromagnetic winding as claimed in claim 1 in which said elongate body portion has a rst end and a second end, said iirst end overlapping said second end, means securing said iirst end to said second end in overlapping relationship, coil leads overlapping said first end, means securing said coil leads to said rst end, said coil having coil ends electrically connected with said coil leads, whereby said first end portion serves as a terminal board for said winding.

6. An electromagnetic winding as claimed in claim 1 in which said coil has an axial length greater than the width of said window.

7. An electromagnetic winding as claimed in claim 1 in which said flaps are oppositely disposed from each other, two of said oppositely disposed flaps overlying the same inner face.

8. An electromagnetic winding as claimed in claim 1 in which said aps are staggered with respect to each other, each flap overlying a different inner face.

9. A circumferential coil wrapper for a coil having a window providing four inner faces, and two end faces, wherein the improvement comprises a blank having an elongate body portion and two aps extending from each side thereof, each llap having a mid portion adapted to overlie the end half of one inner face and two tabs adapted to overlie the adjacent end quarters of adjacent inner faces, and a connecting portion disposed between each ap and said elongate body portion adapted to overlie a portion of an end face, said connecting portion being separated from said body portion and from said flap by fold lines, and said mid portion being separated from said tabs by fold lines.

10. A circumferential coil wrapper for a coil having a window providing four inner faces, and two end faces, whereinl the improvement comprises a blank having an elongate body portion and two aps extending from each side thereof, each iiap having a mid portion adapted to overlie the end half of one inner face and two tabs adapted to overlie the adjacent end quarters of adjacent inner faces, and a connecting portion disposed between each flap and said elongate body portion adapted to overlie a portion of an end face, the transverse dimension of each tab being greater than the transverse dimension of said mid part, and an L-shaped slit separating adjacent portions of a tab and a connecting portion References Cited UNITED STATES PATENTS 1,052,303 2/ 1913 Aven 336--208 XR 2,875,420 2/1959 Hofer et al 336-209 XR 3,317,875 5/ 1967 Williams 336-198 DARRELL L. CLAY, Primary Examiner. T. J. KOZMA, Assistant Examiner.

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