US2710947A - Electrical coil construction - Google Patents

Description

June 14, 1955 J. R. GASTON ELECTRICAL COIL CONSTRUCTION 5 Sheets-Sheet l Filed NOV. 28, 1951 June 14, 1955 J. R. GASTON ELECTRICAL con. CONSTRUCTION 3 Sheets-Sheet 2 Filed NOV. 28, 1951 June 14, 1955 J. R. GAsToN ELECTRICAL COIL CONSTRUCTION 5 Sheets-Shea?l 3 Filed NOV. 28, 1951 man United States Patent O ELECTRICAL COIL CONSTRUCTION John R. Gaston, Gettysburg, Pa., assgnor to Electrocraft Company, Harrisburg, Pa., a partnership Application November 28, 1951, Serial No. 258,569

6 Claims. (Cl. 336-60) This invention relates to what I consider an entirely .new and novel form of winding an electrical coil which may be used in transformers, reactors, relays and various other devices. In the conventional wire wound coils the wire is insulated before it is wound up into coil form. ln the construction to be hereinafter described, coils are wound with sheet strips of suitable current conducting material such as copper or aluminum, together with a strip of suitable insulating material which extends at its opposite edges beyond the width of the metallic strip which may vary in thickness from .002" to .015. sheet strip material may be treated in the case of copper, with chromic acid or a similar acid to render its surface electrically resistant and chemically inert to water. In a similar manner if aluminum be used, this may be anodized for the same purpose. While certain coils may be wound up with a single sheet strip, a plurality of these strips, especially where they are only a few thousandths of an inch thick, may be connected in parallel. Where a parallel arrangement of the strip is used as referred to, l prefer to spot or cold weld the strips together, the welds being in spaced relation depending on the number and width of the strips. At suitable radial distances I have found it highly advantageous to use a strip layer made up in corrugated form to provide cooling ducts within the coils. These corrugated strips may go all the way around a coil or only partially around as will be later referred to in the description of the invention as applied to the winding of the transformer. From the description to be herein described in detail, I have found quite a number of advantages, a few of which will be now referred to:

1. That the heat transfer between layers of cohesive insulating materials between metal strips is about fifteen times greater than that of the same coil wound with conventional wire. The thermal conductivity is based on the constants of either asbestos or paraffin.

2. That only one-fifth as much insulation between layers need be used in a strip wound coil as compared to a wire wound coil.

3. That since the space factor on an average is fifteen per cent better in all desirable applications the cost of the metal will be greatly reduced.

4. Due to the large surface between turns, the electrical capacitance of the coil has been increased and that to ground decreased, thereby enabling it to withstand heavy electrical impulses which a conventional coil of the same rating and size could not approach.

5. Since the coil has a minimum of insulation surface exposed, it may more readily be sealed against moisture.

6. That folded leads make a welded connection possible to enable the coil to be used at very high temperatures, where a brazed lead would melt olf.

7. The corrugated spacers may also be used as radio interference shields with only a slight loss in cooling efciency.

8. Smaller coils may be manufactured to have a snug This area 43/8 by 4, P 5 by 4%.

fit to core material to aid in heat transfer. Larger coils may have corrugated spacers inside and outside of coil, besides ducts, to give maximum heat dissipation.

To further illustrate these advantages, I have tabulated certain data with respect to a conventional wire-wound transformer of 25 kva. with a transformer using my construction wherein I obtain 371/2 kva. In both cases the preliminary volts were 460 and the secondary volts 120. In the conventional wire-wound type which will be hereinafter referred to as C type, as against my new strip wound type which will be referred to as P, type, the following details may be referred to to show the great advantages of my design. In the C type the core window is 2%" by 73/8, the P type 1% by 63/8. The core The total core cubic inches, for type C 630, for type P 635. The effective core cub. inch for C type was 490, for P type 534. Primary turns for type C 96, secondary 25; for type P primary turns 73, secondary turns 19. In both cases there is the same ratio namely, 3.84. The coil winding bulge factor for C type is l per cent minimum and for P type per cent maximum. Effective duct surface with spacers for C type 1,005, for P type 1,656 sq. in. Core radiating surface for C type 372, for P type 418. Total radiating surface for C type 1574, for P type 2260. Primary resistance for C type .074 ohm, for P type .043 ohm. Secondary resistance for C type .0036 ohm, for P type .0023 ohm. Weight of copper for C type 471/2 lbs., for P type 391/2 lbs. Total weight of core and coils C type 210 lbs., P type 210 lbs. With the C type transformer delivering kva. the temperature was 60 C., and the P type delivering 371/2 kva. the temperature was 56 C.

From the above gures it will be seen with the same weight of core and coils I have secured an increase of per cent in the output of the transformer, at a lower temperature.

All these advantages are obtained by the special construction which will now be described.

Figure 1 is a plan View of my invention as used in the winding of a shell type transformer;

Figure 2 is a side View of Figure l;

Figure 3 is a fragmentary view of a single coil turn and insulating strip having its edges inturned to protect and help support the strip conductors;

Figure 4 is a view of a terminal used with the strip 3 or sheet conductor such as shown in Figure 3;

Figure 5 shows how a terminal similar to that shown in Figure 4 can be connected by spot welding to a sheet conductor;

Figure 6 is a perspective View used with a coil winding;

Figure 7 is a fragmentary view showing an air duct at the .iunction of a primary turn and a secondary turn;

Figure 8 is a partial view of the special air ducts at one corner turn and how these ducts may extend all the way of a positioning stop around the coil winding;

Figure 9 is a fragmentary View of the ends of four turns of the high voltage winding with the end of a corrugated turn attached to an adjacent end forming a part thereof and also providing a plurality of cooling ducts;

l' inside end of the high voltage coil is started;

Figure 14 is a view similar to Figure 13 of the outside end of the high voltage coil;

Figure 15 is a schematic view showing how the secr ondary turns are divided into two groups connected in series through a Ventilating corrugated conductor;

Figure 16 is a diagrammatic view of the right hand end of Figure 15;

Figure 17 is a diagrammatic view of the left hand end of Figure 15;

Figure 18 is a plan view of Figure 15 with windings and insulation extended;

Figure 19 is a side view of Figure 18;

Figure 20 is a fragmentary longitudinal view of Figure 15 with adjacent turns in position;

Figure 21 is a diagrammatic view showing how a coil can be built up with spaced corrugated turns to give ventilation.

In the various views wherein like numbers refer to corresponding parts, 1 is the core of a transformer made up of suitable satisfactory magnetic material and associated with the core 1 are the high and low voltage coils as shown in Figure 1. The high voltage winding has an interior portion marked H. V. and an exterior portion likewise indicated. Between these two portions of the H. V. winding is the low voltage winding indicated by the letters L. V. Both the high voltage and the low voltage windings are made up of a plurality of metallic strips as heretofore described. The space which these turn layers occupy are indicated by the numbers 2, 3, 4, etc. and between these turn layers a strip of corrugated metal, preferably the same kind as the other turns is positioned and preferably forms one of the layers of each set of turns thereby not only providing a large cooling area between the convolutions but also serves as a conductor of current in parallel with the adjacent layer turn. However, the corrugated strip may be an individual turn of suitable cross section to carry the necessary current. As shown in Figure 1 the corrugated strips are shown only at the opposite ends of each winding layer. However, they may go completely around the winding as is indicated diagrammatically in Figure 8 which illustrates one corner of a set of turns, in some cases, and as better illustrated in Figure 21. However, by using the space corrugated turns as shown in Figure 1 the amount of metal in the core is held to a minimum, for the reason that if the corrugations were held along on the sides, the winding would extend accordingly and require wider core laminations. Where a single at strip coil turn is used, I prefer to have the insulating strip for it arranged as shown in Figure 3, wherein the edges of the insulation is folded over so as to provide suitable protection at the edge of the strip s. With this type of construction, the insulating strips f give an example of the transformer described, which is only a very few thousandths of an inch thick and may be of asbestos paper having the technical name of Quinterra or other satisfactory organic material. In making a connection to the' strip s, a terminal t, folded up as shown in Figure 4 is utilized, the material being the same thickness as the strip s, the terminal being spot or cold welded as shown in Figure 5. Where a corrugated turn is used in parallel with an adjacent turn it is preferably spot or cold welded at w to the adjacent strip conductor s, as shown in Figure 9. To assist in holding the multiple turn conductors in place a support l0 is used as shown in Figure 6, one end being spot welded at 11 to the starting end of the conductor strip with another support lil spot welded at 12 to the end of the coil or winding which is shown as a fragmentary portion at the left of the turn shown in Figure 12. This construction is further illustrated on an enlarged scale in Figure 13 which shows the inside start of the high voltage winding. The outside end of the H. V. coil is shown in Figure 14 and in this case the terminal t has a plurality of pins 13 to which 0r around which is fastened a wire 14 which engages cooperative pins 15 on the support member 10. In Figure l1 the insulating strip has the fold f in position over the edge of the strip s where a single strip conductor is used, but where a plural strip conductor is used as shown in Figure 10 this insulating part is folded so as to engage the edge of each strip forming a compound conductor in which the corrugated strip R forms a part. In making up a higher voltage winding, I use to great advantage the construction shown in Figures 15-17. In this construction the corrugated turn R has a split 16 and fastened as by spot or cold welds 17 to one edge of the turn R is a at strip 18 and associated with it is a strip insulator 19. To the adjacent end of the turn R at the slit or gap 16 is another conductor 20 similar to 18 and an insulator similar to 19. Assuming that current is owing in the strip 18 in the direction of arrow 22 which ows into the corrugated conductor R and around to the strip 20 and continues around on this in the same direction, and connected as desired or required in proper relationship to the next coil above the corrugated turn. By using this construction the number of turns in the H. V. winding can be greatly increased for a given section of suitable metal. In making up the coils as the insulation strips are being passed into position, the strips are tested with a suitable voltage. As the folds are started as shown in Figure 3 they pass under heated roller which firmly compresses the fold over a suitable binder and stiifening material which is applied just forwardly of the fold as it made thereby providing a coil with sealed and rigid edges.

From what has been said it will be readily understood that many of the details may be varied without departing from the scope of my invention and the spirit of the appended claims.

Having thus described my invention, what I claim is:

l. An electrical coil construction including a sheet strip of suitable metal wound up in turn layer form with a strip sheet of suitable insulating material being between said turn layers while at radially spaced intervals a metallic sheet in corugated form is utilized in cooperative relationship with at least one of said turn layers, means for making a suitable electrical connection with said turn layers at their beginning and ends, said means comprising a plurality of end folds with the end of the metal strip securely anchored to the beginning of the first fold, said strip of insulating material being wider than the metal strip and located so its edges project beyond the edges of the metal L strips, the insulating strip being anchored to the rst metal fold forming a U within which the end of the insulating strip is gripped by pressure applied to this fold, and further means for assisting in holding the end edge of the insulating strip within said fold.

2. An electrical coil comprising a plurality of relatively Y.' thin strips of suitable bare metal electrically connected in parallel relationship to form a single conductor wound up in coil form with a sheet of insulation wound up at the same time between the said metal turns, and a strip of suitable bare relatively thin corrugated metal wound up to form cooling means with any one of said conductor strips and electrically forming part of said conductor strip, said insulation being wider than the width of said metal conductors as and for the purpose described.

3. In an electrical coil construction means for reducing to a minimum void spaces between coil turns, said means to a minimum void spaces between coil turns, said means comprising thin flat uninsulated strip conductors arranged in parallel to form a single conductor with a thin strip of suitable insulating material between conductors, means being provided for greatly improving the cooling characteristics of the coil, said means including corrugated metal turns disposed between the at coil turns, said corrugated turns being utilized as single conductor turns arranged in parallel with the flat strip turns, said insulating material having preferably a width to extend beyond the edges of the conductor strips and being folded to form edge seals along the conductor turns.

5. An electrical coil construction comprising a plurality of superimposed strips of suitable metal wound up to form a plurality of turn layers with a strip sheet of insulation between said metal layers, the sheet of insulation being wider than the metal strip and located so its edges project beyond the edges of said turn layers and providing the only insulation between said layers, at least one of the metal strips being corrugated and in radial spaced relation to the other.

6. An electrical coil construction especially adapted for transformer use, said coil being made up of turns of suitable metal in strip form with suitable thin sheet insulation between conductor turns, the insulating sheet being wider than the metal turns, thereby providing high internal capacity and enabling the coil to withstand heavy line surges, certain of the metal turns being corrugated for the purposes described including that of an agent to act as a high frequency shield.

References Cited in the file of this patent UNITED STATES PATENTS 772,288 Neall Oct. 11, 1904 1,394,044 Stephens Oct. 18, 1921 1,543,001 Gaynor June 23, 1925 1,851,184 Holmes Mar. 29, 1932 2,246,159 Work June 17, 1941 2,295,415 Monroe Sept. 8, 1942 2,378,884 Seifert .Tune 19, 1945 2,585,037 Robinson Feb. 12, 1952 FOREIGN PATENTS 269,933 Great Britain Feb. 2, 1928

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