GB2294593A - Electrical winding and method of making the same - Google Patents

Abstract

A generally rectangular electrical winding 30 is formed from a continuous length of laminated foil ribbon with each turn being generally planar and four-sided. At each corner of the turn joining a pair of adjacent orthogonally related generally straight sides, the ribbon is creased and rises out of the plane defined by the adjacent sides so that a continuous edge 38 of the ribbon defines an interior opening of the winding. Each successive turn overlies the preceding turn. <IMAGE>

Description

ELECTRICAL WINDING AND METHOD OF MAKING THE SAME This invention relates to an electrical winding formed from a laminated foil ribbon and, more particularly, to such a winding having multiple turns and wherein the overall height is minimized.

There are various applications requiring that an electrical winding be formed from a laminated foil ribbon and wherein the plane of the ribbon is maintained orthogonal to the axis of the winding. The most common way of forming such a winding is to form each turn of the winding as four generally straight sides with the ribbon having a 90 degree overlying fold at each corner.

A problem with this approach is that there is a double thickness of ribbon at each corner, thereby limiting the number of turns in the winding for a given winding height. It Is therefore an object of the present invention to provide an electrical winding of laminated foil ribbon which allows more turns to be provided within a given winding height.

The foregoing and additional objects are attained in accordance with the principles of this invention by providing a generally rectangular electrical winding comprising a continuous length of laminated foil ribbon formed into a generally planar four-sided turn. At each corner joining a pair of adjacent orthogonally related generally straight sides, the ribbon is creased and rises out of the plane defined by the adjacent sides so that a continuous edge of the ribbon defines an interior opening of the winding.

In accordance with an aspect of this invention, the ribbon forms multiple four-sided turns, with each successive turn overlying the preceding turn.

According to the invention, a method of forming a generally rectangular electrical winding from a continuous laminated foil ribbon so that a continuous edge of the ribbon defines an interior opening of the winding, comprises the steps of: (a) forming a first side of a turn of said winding by laying a generally straight first length of said ribbon in a plane; (b) forming a second side of said winding turn by creasing said ribbon at a first corner of said turn to lay a second generally straight length of said ribbon in said plane and extending orthogonally to said first length, with said continuous edge rising out of said plane at said first corner;; (c) forming a third side of said winding turn by creasing said ribbon at a second corner of said turn to lay a third generally straight length of said ribbon in said plane and extending orthogonally to said second length, with said continuous edge rising out of said plane at said second corner; and (d) forming a fourth side of said winding turn by creasing said ribbon at a third corner of said turn to lay a fourth generally straight length of said ribbon in said plane and extending orthogonally to said third length, with said continuous edge rising out of said plane at said third corner.

The foregoing will be more readily apparent upon reading the following description in conjunction with the drawings in which like elements in different figures thereof are identified by the same reference numeral and in which: FIGURE : is a perspective view of a transformer core with which the inventive winding finds utility; FIGURE 2 is a side view of the core of Figure 1 having thereon a winding formed in accordance with the prior art where the corners are folded as shown in Figure 2A; FIGURE < is a perspective view of a winding constructed in accordance with this invention; FIGURE 1 is a side view of the core shown in Figure 1 with the winding of Figure 3 thereon; and FIGURES 5A-5J are alternate plan and side views illustrating the steps in the formation of the winding shown in Figure 3.

Figure 1 illustrates a ferrite transformer core 10 with which the present invention finds particular utility. As shown, the core 10, when viewed from the side, is generally E-shaped (rotated 90 degrees) with a base 12, a central arm 14, and a pair of end arms 16, 18 of equal height as the central arm 14. The end arms 16, 18 are equally spaced from the central arm 14 so as to provide channels 20, 22, respectively, therebetween. In a particular application with which the present invention is concerned, it is desired to provide an electrical winding around the central arm 14 of the core 10. It is required that the winding have a predetermined number of turns, be,formed of a laminated foil ribbon, have the plane of the ribbon maintained generally parallel to the base 10, and fill the channels 20, 22 to a height no greater than the height of the arms 14, 16 and 18.

Figure 2 shows a side view of the core 10 supporting a winding 24 formed according to the prior art wherein the corners of each turn are folded. Thus, as shown in Figure 2A, the winding 24 is formed by providing a laminated foil ribbon 26 which is laid flat and then folded over on itself at each corner 28 to define two adjacent orthogonally related sides. As is clear from Figure 2A, at each of the corners 28, there is a double thickness layer of the ribbon 26. Thus, as shown in Figure 2, the height of the winding 24 is twice the thickness of the ribbon 26 times the number of turns making up the winding 24.

Figure 3 Illustrates an improved winding 30 formed according to this invention. The winding 30 is formed without any overlying folds and therefore without any double thickness corners, in contrast to the winding 24.

When supported within the channels 20, 22 of the core 10, as shown in Figure 4, more turns of the winding 30 can be accommodated within the height restrictions of the arms 14, 16, 18 than the winding 24, as will become clear from the following discussion.

The formation of the winding 30 is illustrated in Figures 5A-SJ, with alternate figures being plan and side views of the formation steps. The winding 30 is formed from a laminated foil ribbon in such a manner that a continuous edge of the ribbon defines an interior opening of the winding, with the winding 30 being generally rectangular when viewed in plan. As shown in Figures 5A and 5B, the first step in forming the winding 30 is to lay a first generally straight length 32 of the ribbon in a plane to thereby define a first side of a winding turn.As shown in Figures, 5C and 5D, the ribbon is then creased at a first corner 34 and a second side of the winding turn is formed by laying a second generally straight length 36 of the ribbon in the plane of the first length 32 and extending orthogonally to the first length 32. The inside continuous edge 38 of the ribbon rises out of the plane of the first and second lengths 32, 36 at the corner 34, as is clear from the perspective view of Figure 3.

Figures 5E and SF illustrate that a third side of the winding is formed by creasing the ribbon at a second corner 40 and laying a third generally straight length 42 of the ribbon in the plane of the first and second lengths 32, 36 orthogonally to the second lengths 36.

As at the first corner 34, the continuous edge 38 of the ribbon rises out of the plane of the lengths 32, 36, 42 at the second corner 40. As shown in Figures 5G and 5H, a fourth side of the winding 30 is formed by creasing the ribbon at a third corner 44 and laying a fourth generally straight length 46 of the ribbon in the plane of the lengths 32, 36, 42 and extending orthogonally to the third length 42. The continuous edge 38 rises out of the plane at the third corner 44, as it does at the corners 34, 40. Thus, there has been formed a generally rectangular electrical winding turn from a laminated foil ribbon wherein a continuous edge 38 of the ribbon defines an interior opening of the winding.

When it is desired te form a multiple turn winding, as shown in Figures SI and SJ the ribbon is creased at a fourth corner 48 and a fifth generally straight length 50 of the ribbon is laid overlying the first length 32, with the continuous edge 38 rising up out of the plane(s) of the various ribbon lengths at the fourth corner 48. The steps illustrated in Figures 5C-5J are then repeated, with each successive turn overlying the preceding turn, until the required number of turns is reached.

With the improved winding 30 described above, the overall winding height does not increase as a linear multiple of the number of winding turns, as it does with the folded winding 24. Instead, the overall winding height is a fixed height, attributed to the corner creasing, plus the number of winding turns times the ribbon thickness. The height of the corner crease is related to the width of the ribbon. Thus, a winding having forty turns is not necessarily twice as high as a winding having twenty turns. Instead, the additional twenty turns only adds twenty times the thickness of the ribbon to the height of the first twenty turns of the winding. Therefore, based upon the thickness and width of the ribbon, there is always some minimum number of turns above which a winding of the form shown in Figure 3 according to this invention will have less height than a folded winding of the form shown in Figure 2.

Claims (8)

1. A method of forming a generally rectangular electrical winding from a laminated foil ribbon so that an edge of the ribbon defines an interior opening of the winding, comprising the steps of: (a) forming a first side of a turn of said winding by laying a generally straight first length of said ribbon in a plane; (b) forming a second side of said winding turn by creasing said ribbon at a first corner of said turn to lay a second generally straight length of said ribbon in said plane and extending generally orthogonally to said first length, with said edge rising out of said plane at said first corner;; (c) forming a third side of said winding turn by creasing said ribbon at a second corner of said turn to lay a third generally straight length of said ribbon in said plane and extending generally orthogonally to said second length, with said edge rising out of said plane at said second corner; and (d) forming a fourth side of said winding turn by creasing said ribbon at a third corner of said turn to lay a fourth generally straight length of said ribbon in said plane and extending generally orthogonally to said third length, with said edge rising out of said plane at said third corner.

2. The method according to claim 1 of forming a multiple turn winding further comprising the steps of: (e) creasing said ribbon at a fourth corner of said turn to lay a fifth generally straight length of said ribbon overlying said first length, with said edge rising out of said plane at said fourth corner; and (f) repeating the aforementioned steps (b) through (e) with each successive turn overlying the preceding turn.

3. An electrical winding formed in accordance with the method of claim 1.

4. A multiple turn electrical winding formed in accordance with the method of claim 2.

5. A generally rectangular electrical winding wherein a laminated foil ribbon is formed into a generally planar four-sided turn, and wherein at each corner joining a pair of adjacent orthogonally related generally straight sides, the ribbon is creased and rises out of the plane defined by said adjacent sides so that an edge of said ribbon defines an interior opening of said winding.

6. The winding according to claim 6, wherein the ribbon forms multiple four-sided turns, with each successive turn overlying the preceding turn.

7. A generally rectangular electrical winding constructed substantially as hereinbefore described with reference to Figures 3 to 5J of the accompanying drawings.

8. A method of forming a generally rectangular electrical winding substantially as hereinbefore described with reference to Figures 3 to 5J of the accompanying drawings.