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Publication numberUS3911332 A
Publication typeGrant
Publication dateOct 7, 1975
Filing dateDec 11, 1972
Priority dateDec 29, 1971
Publication numberUS 3911332 A, US 3911332A, US-A-3911332, US3911332 A, US3911332A
InventorsKunkel George M
Original AssigneeKunkel George M
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Wound transformers and machine for making the same
US 3911332 A
Abstract
A wound transformer which can include additional capacitance and impedance members for its respective primary and secondary windings, and also an electrostatic shield. The transformer may be wound spirally, with a flat insulation winding holding interleaved metallic elements such as the primary and secondary winding, and a primary and secondary capacitance member. A primary and/or a secondary impedance member may be wrapped around all or part of a respective primary or secondary winding, in which event the winding material may have any desired cross-section. Means is provided expeditiously and economically to form the windings to a non-circular section.
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Description  (OCR text may contain errors)

United States Patent Kunkel Oct. 7,1975

[54] WOUND TRANSFORMERS AND MACHINE 3,378,626 4/1968 Tucker... 336/84 FOR MAKING THE SAME 3,495,202 2/1970 Parker 336/223 3,634,800 1/1972 Fisher..., 336/223 [76] lnventor: George M. Kunkel, 8402. 3,704,390 11/1972 Grahame 336/69 McGroarty, Sunland, Calif. 91040 3,750,071 7/1973 Elcy 336/84 [22] Filed: Dec. 11, 1972 Appl. No.: 313,847

Related U.S. App1icati0n Data Continuation-impart of Ser. No. 213,337, Dec. 29, 1971, abandoned.

US. Cl. 317/157.62; 336/192; 336/223 Primary ExaminerL. T. HiX Attorney, Agent, or FirmDonald D. Mon

[5 7] ABSTRACT spective primary or secondary winding, in which event the winding material may have any desired crosssection. Means is provided expeditiously and economically to form the windings to a non-circular section.

54 Claims, 22 Drawing Figures illlllllllllll Sheet 1 of4 US. Patent Oct. 7,1975

INVENTOR. GEO/QGf/W KU/VKfL b, M P

ATTORNEYS US. Patent Oct. 7,1975 Sheet 2 of4 L tr 5 mm w W. W a M W w 4A a a m t B Z IA 0 3 n m 4 9 M K w n u u I J E v "m .m" z T 1 w m m a 9 l W :3 "u" 3 K 7 m u Z n OJ 1 6 n m M m \l in Cl F W F US. Patent 0m. 7,1975

Sheet 4 of 4 WOUND TRANSFORMERS AND MACHINE FOR MAKING THE SAME CROSS-REFERENCE TO OTHER APPLICATIONS This patent application is a continuation-in-part of applicants co-pending US. patent application, Ser. No. 213,337, filed Dec. 29, 1971, now abandoned.

This invention relates to a wound transformer which preferably has a polygonal cross-section, and to a method for winding the same. I

A transfonner is designed to transform a signal from a primary winding to a secondary winding where a specific frequency or a band of frequencies are of concern. By the nature of the design, frequencies other than those of concern (known as noise) are also trans-' formed, and such transformation can be highly undesirable. It is known to attempt to minimize the noise transmission by utilizing an electrostatic shield, which is intended to reduce the effective capacitve coupling between one winding and another. Which a shield, as it has heretofore been constructed, has been very costly, and its reliability has been relatively low. Another known means for minimizing noise is to utilize low-pass filters on the transformer leads. However, these are very costly, add weight to the system, occupy excessive space, and can themselves create a gain or loss at the desired transformer frequency, and can significantly affect the output voltage and power factor of the transformer.

Transformers of the type contemplated by this invention may be expected to be widely used in airborne arid space applications, and other electronic and commnication systems, and around computers where stray signals are intolerable. Although users are willing to spend whatever money it takes to reduce these undesirable features, the transformer of this invention accomplishes its objectives at a much lower cost in termsof weight, size and dollars than has heretofore been believed to be possible.

Presently known transformers which utilize electrostatic shields have windings formed of round wire which is wound upon a bobbin with flanges on both sides. When the transformer is wound in this manner and a simple faraday shield is used, special insulation material must be utilized between the inner winding and the shcild. Because the wires which lead to the inner winding must pass alongside the faraday sheild, the shield must be cut and then placed in such a fashion as to insure that the shield itself does not cut through the insulation of the wires. The lead wires which pass to the inner winding must also pass beside the outer winding, thereby reducing the anticipated isolation which would otherwise be obtained by means of the shield, because of the resultant capacitive coupling. Because the outer winding must be wound on top of the sheild, placing a low-impedance tab on the shield becomes difficult and awkward. Therefore, a wire is used, but the impedance of the wire in turn greatly reduces the effectiveness of the shield. Accordingly, attempts to utilize a faraday shield, which should be an elegantly simple solution to at least a major part of the noise.

supplying'to the transformer an inductance and/0r impedance respective to the primary or secondary windings. Such means has not been attainable in the prior art, and this invention enables this objective to be realized. Such means significantly reduces noise, and doesso in a compact device which can readily and economically be manufactured.

ln adevice according to the invention:

A. a lesser transformer window area can be used in the design of atransformerof 7 given properties;

B. the electrostatic shield may utilize the same material as the windings of the transformer; I

.C. thesame material that insulates the windings fro each other can also be utilized to ins luate the electrostatic shield from the windings; I

(d). the breakdown voltage and capacitance between the transformer windings and the electrostatic shield can be determined by selecting the number of turns of insulation material between them;

E. an extended electrostatic shield can be made from a single length of metallic material readily wound upon a bobbin;

F. external equipment can readily be connected directly to the electrostatic shield and to the other metallic elements of the device without reduction of reliability or increase in manufacturing .time and expense;

G. the transformer can betwound on a square or a rectangular bobbin while maintaining the feed speed of the materials of contsruetion at a relatively constant velocity;

H. the internal direct leakagecapacitance of either the primary and/or the secondary windings can be increased, resulting in restriction of the frequency range at which the transformer will operate; and.

l. the internal leakage inductance-of either the primary and/or the secondary winding can be increased, resulting in the restriction of the frequency range at which the transformer will operate. 1

A transformerwinding member according to this invention is wound on a bobbin. It comprises a spirallywound, continuous, wide piece of electrical insulation material, between the convolutions of which there are placed spirally-wound turns of electrically conductive material which are spaced apart from one another along the length of the spiral so as to'form'conductive portions of the transformer. There-may be wrapped between the turns of the insulation material a length of electrically conductive material similar to that of the windings which stands between theprimary and secondary windings ,to -form an electrostatic shield. The turns of insulation material which are formed between the turns of the windings and shield serve to insulate them from one another and to form a transformer construction.

According to an optionalfeature, a plurality of layers of insulation material may simultaneously be wound so that adjacent but electrically disconnected conductive layers may be wrapped in adjacency 'to the primary and secondary windings so as to form respective primary and secondary capacitance members for reasons yet to be described. 1

According to still another optional feature of the invention. ferro-magnetic means may be inserted between certain turns of the insultation member and then be wrapped around all or part of respective primary pedarlce members, and as to this optional feature, the

impedance member may usefully be provided with windings of round wire, not merely with flat foil.

According to another preferred but optional feature of this invention, the winding member may be wound upon a square or rectangular bobbin utilizing a belt drive driven at a constant linear velocity, which belt will drive the bobbin at an oscillating angular rate which, however, draws the material of construction 'from a source of supply at a constant rate that is directly proportional to the velocity of the belt.

The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings in which:

FIG. I is a classical T drawing of the equivalent circuit for a transformer;

FIG. 2 is a T drawing showing the equivalent circuit which results if the transformer is modified by the addition of an electrostatic shield between the primary and secondary windings;

FIG. 3 is a T" drawing showing the equivalent circuit which results if the transformer is modified by the further addition of a primary and a secondary capacitance member and a primary and a secondary inductance member;

FIG. 4 is a schematic drawing showing the construction of one embodiment of a transformer winding member according to the invention;

FIG. 5 is a cross-section of part of one turn in FIG.

FIG. 6 is an end view of a completed winding member according to the invention;

FIG. 7 is a cross-section taken at line 77 of FIG. 6;

FIG. 8 is a side view'showing a feature of construction of the invention in an intermediate stage of manufacture;

FIG. 9 is a view the same as FIG. 8, but with the construction completed;

FIG. 10 shows the winding member of FIG. 6, to gether with a magnetic core which completes the transformer;

FIG. 11 shows an alternate embodiment of the invention;

FIG. 12 is a side view, partly in cutaway crosssection, schematically showing a device for winding the winding member of FIG. 4;

FIG. 13 is a cross-section taken at line l3l3 of FIG. 12;

FIG. 14 shows the winding member of FIG. 4 in the process of its manufacture, utilizing a preferred embodiment of the device of FIG. I2;

FIG. 15 is a side view, partly in cutaway crosssection, showing the winding device of FIG. 12 in further detail;

FIGS. 16 and 17 are fragmentary laid-out views schematically showing some considerations regarding the electrostatic shield; I

F IG. [8 is a fragmentary cross-section of a modified part of FIG. 4;

FIG. 19 is a fragmentary laid-out view taken at line 19l9 of FIG. 18;

FIG. 20 is a fragmentary view of a modified portion of FIG. 6;

FIG. 21 is a fragmentary cross-section taken at line 2l-2l of FIG. 20; and

FIG. 22 shows a modification of a portion of FIG. 9.

Some of the features of this invention can be utilized in transformers of conventional design, and with theuse of wound wire. However, when fiat foils are used for the conductive elements of the transformer, all of the features can be used, and there results a tranformer which constitutes a major stride in the art.

A conventional transformer basically consists of an iron core with a pair of windings around it which are inductively linked to each other by it. One of the problems inherent inconventional transformers is the transmission of noise between windings derived from undesirable electrostatic and electromagnetic effects. For this reason, and electrostatic shield and external filters are often provided. An electrostatic shield is a grounded conductive shield that stands between the two windings, and this does tend to reduce the noise.

It is not generally realized that further improvements can result from the provision of a capacitive property within each of the primary and secondary windings, and from the provision of an inductive property within each of them. Previous to this invention, such realization would have done little good, because there was no means to provide the same in a practical and economical transformer. This invention makes such a transformer practical. It eliminates the need for bulky and costly in-Line filters.

It is not considered necessary or even appropriate in this specification to develop the underlying theory of behavior of the transformer itself. Suffice it to say that, with the construction disclosed herein, transformers can readily be manufactured which have the equivalent circuits shown in FIGS. 2 and 3, and which, when their physical properties are selected appropriately with respect to the circuit in which they are to be used, produce an output which is as free of noise as is attained by the best of the presently known transformer-filter systems. 1

In FIGS. 1, 2 and 3, the symbols have the following meanings:

R,, Primary Resistance R Secondary Resistance R Shunt Core-Loss Resistance" 7 k L Primary Shunt (mutual) Inductance C,, Primary Distributed Capacitance C Secondary Distributed Capacitance L Primary Leakage Inductance L Secondary Leakage Inductance C Direct Input-to-Output Leakage Capacitance C Direct Primary Leakage Capacitance C Direct Secondary Leakage Capacitance As to the effects of the various elements, the following statements apply: I

The addition of:

A. Primary inductance increases 1.

B. Secondary inductance increases L I C. Primary capacitance increase C D. Secondary capacitance increases C and E. Electrostatic shield decreases the effective leakage capacitance C Persons skilled in the art will recongize from FIGS. 1-3 and the above statements theutility of the various elements, the means for selecting their parameters for best results, and the means for connecting them into appropriate circuitry.

An object of this invention is to provide means not only for winding a lightweight, inexpensive and efficient transformer which need not have an electrostatic shield, but also one which may not only have an effective electrostatic shield but one which may also, or instead, have additional primary and secondary capacitance and impedance members associated with the respective windings. Furthermore, this invention accomplishes these objectives by means which can be manufactured at a high rate of production.

Because of the use of the impedance members, and for the most effective use of a magnetic core yet to be described, it is preferable to wind the winding member of the transformer on a noncircular, polygonal bobbin which is rectangular. Many of the objectives of this invention can be achieved with a round bobbin, but in that case, the impedence members cannot ordinarily be as conveniently provided.

The presently preferred embodiment of winding member 35 for the invention is shown in FIG. 6. It includes a mounting member 36, which is a hollow prismatic structure made of insulating material, upon which there is spirally-wound a primary section 37, a separation section 38 and a secondary section 39. These sections will be more fully discussed in detail later in this specification.

A primary impedance member 40 and a secondary impedance member 41 are wrapped around all or part of the respective primary and secondary sections in a manner yet to be described.

Primary leads 42, 43, secondary leads 44, 45, electrostatic shield lead 46, primary capacitance lead 47, and secondary capacitance lead 48 extend from internal portions yet to be described, and are for the purpose of connecting the appropriate parts of the transformer to external cicuitry.

The winding itself is formed by spirally winding around a bobbin, which for this purpose may be considered the mounting member 36, a layer 50 of insulation material such as mylar or teflon. Other materials which have good insulating properties and sufficient flexibility, such as paper, may instead be utilized. It ispreferably fed from a reel and is best shown in FIG. 7 as having a dimension 5] of width and a dimension 52 of length. It is wound on the bobbin so as to form a winding with a central longitudinal axis 53 (FIG. to which the dimension 51 of width is parallel. The spiral will wind to form a stack of increasing thickness as the bobbin is turned so as to form the successive turns or convolutions.

Similarly, an elelectrically conductive material is utilized to form the various windings, shields and other members. It is best shown in FIG. 8. This material is laid down in the form of layers 54 having a dimension 55 of width, which will generally be less than the dimension of width of the insulation material, and a dimension of length parallel to that of dimension 52. The conductive material is preferably selected from the group consisting of aluminum, aluminum alloys, copper and copper alloys, although any conductive material of suitable electrical properties may instead be used.

In the construction of this device, and depending upon the voltages to be transformed and the loads which are to be carried by it, the thickness of the layers of insulating and metallic material are those of foils, and they conveniently have a minimum width and thickness as dictated by the said voltage and current.

It is evident that the insulation material will be formed as a continuous length and will comprise the fundametnal building unit of the winding member. The electrically conductive material will be fed intermittently for just so many turns as are required to construct the respective element and then, for electrical spacing between the two, metallic material will not again be fed until a sufficient number of turns of insulation material have been wrapped to give the desired amount of spatial and electrical separation from the other conductive elements. Accordingly, this device, when made in its simplest manner, comprises a continuous spiral turn of insulation material interleaved with a primary winding and a secondary winding between adjacent insulation convolutions, and spaced apart from one another electrically by a plurality of turns of insulation material which do not have adjacent to them any of the electrically conductive material. Similarly, the electrostatic shield is formed by providing a length of the electrically conductive material in the separation section where it is both spatially and electrically disconnected from the primary and secondary windings. As will later be discussed, it is preferable for this length to be such as to form one complete turn, but the provision of less than one complete turn is also contemplated by the invention. In these two forms of the invention, where there are no immediately adjacent turns of electrically conductive material, with or without electrostatic shield, it is only necessary to utilize one layer of insulation material because, when it returns around the next turn, it will overlay any adjacent metal material. If, however, thereare to be two concurrent metallic turns such that one metal layer will overlap the other within the same turn, then there must be two or more layers of insulation material utilized, and it is this feature which enables the capacitance members to be formed in the manner yet to bedescribed. Accordingly, this most complicated means of manufacture of the device will be described herein, it being understood that the simpler forms of the transformer, namely one without an electrostaic shield, or with an electrostatic shield but lacking the capacitance windings, can be made utilizing only one single layer of insulation material, and only a part of the windingma'chine, where the primary and secondary windings and the electrostatic shield can be of different pieces frorhfthe same roll of material.

The winding member of FIG. 6, which is schematically shown in FIG. 4, is constructed by means of the machine shown in FIG. 15. The machine 60 has a shaft 61 turning a bobbin 6iwhich has a square periphery 63. The mounting member 36 is mounted onto the square periphery, and the winding member is formed by rotating the bobbin in the direction indicated by arrow 64.

Reels 65, 66 carry lengths of insulation material, while reels 67, 68 carry metallic materials. The outfeed from the reels is intended to be at a substantially constant linear velocity, and the material passes from the respective reels over idler wheels 69, which are appropriately placed so as to gather and guide the materials. The supply of the insulation material will be continuous, but that of the metal will be discontinuous. Flying knives or other intermittent cutting and feeding devices, the details of which form no part of this invention, will be provided for the discontinuous insertion of lengths of metal material between the layers of insulation at the appropriate times.

Because the bobbin is non-circular, and because it is desirable to have as constant a velocity of feed of the foil material to the bobbin as possible in order to avoid wrinkling and breakage, the machine is constructed so as to exert a steady demand. As best shown in FIG. 12,

a drive wheel 70 is provided which drives a belt 71 at a constant linear velocity. this belt engages a shaft 72 which has an outer drive periphery 73 that is gemetrically similar to, and preferably of aboutthe same dimensions as, those of the mounting member 36. Accordingly, the angular velocity of the central shaft 72 will fluctuate periodically as the belt drives at a constant linear velocity.

A web 74 of material, which'may be considered the output from the reels shown in FIG. 15, is wrapped around the similarly shaped mounting member. The result of driving a square bobbin by a continuously moving belt, and then winding the web material onto a surface of geometrically similar shape, results in motion of the web of a linear velocity which is constant within the tolerances which can be withstood by the material. Of course, if a square bobbin is not used, then the shape of the drive shaft will be similar to whatever shaped is used, instead of being square. I

This mechanism comprises a very simple means for forming a non-circular winding without having'to vary the speed of supply at the source. It will be recongized that, as the winding grows on the bobbin, the simplified geometrical relationship show in FIG. 12 will change somewhat, and a means of overcoming this disadvantage is shown in FIG. 14.

In FIG. 14, drive wheel 70 is shown'in three successive positions, 75, 76 and 77, which positions result from being moved along a track as the winding grows on the bobbin. This movement need not be particularly large, and it has as its objective to maintainthe web portions 78 sensibly parallel to, or perpendicular to, the drive belt portions 79. The angular relationships will be the same when the drive belt is perpendiculr as when it is parallel, and both arrangements are contemplated by this invention. As a result, the velocities of the belt and of the web will remain substantially constant and directly proportional to one another. A simple means to accomplish this objective is'to shift the center of the wheel along an arc defined by positions 75, 76 and 77, using a lead screw which' responds to the number of turns placed on the bobbin; The drive wheel 70 is reset to its initial position 75 each time that a new winding is to be wound.

The reason for'the periodic variation in-the shaft speed, the unfortunate aspects of which are overcome in this arrangement, is illustrated by the two bobbin positions 80, 81, which are shown in solid and coded line, respectively. These illustrate that, unless an arrangement is made such that the angular velocity of the bobbin varies, there would be a variationin the instantaneous velocity of the web away from its source. This is overcome by the simple expediant of driving a shaft at a surface which has an external configuration which is geometrically similar to that of the surface upon which the winding is being wound, so that the demand is the sameas the drive, i.e., constant.

With the foregoing in mind, reference should now be made to FIG. 4, wherein only the electrically conductive portions of the winding member are shown. An attempt also to-incorporatein this drawing the insulation layers results in an overly-large and dazzling drawing which is most difficult to read, I

Primary winding 85 is shown in solid line as having three complete turns. A complete turn is defined as a continuous length of material which, when wound around the axis, will intersect a single radius twice. An

electrostatic shield 86, shown in dashed line, is radially spaced apart and electrically spaced from winding 85. It has overlapped ends and preferably forms slightly more than one complete turn so as completely to shield the primary winding. I-Iowever,as will later be discussed, this invention comprehends the usage of an electrostatic shield of less than and more than one complete turn, and whose width compared to that of the windings is equal to, or greater, or less than they are. Outside, and wrapped around the electrostatic shield, is secondary winding 87,also shown in solid line and having three turns, this being shown for convenience as a 1:1 transformer, although the ratio could, of course, be otherwise. Without the electrostatic shield, the primary and secondary windings would comprise a classical simple transformer. With the electrostatic shield, it comprises an improved transformer. Either of these constructions could be made by utilizing only a single wrapping (length) of insulation material in the sense of being made from a single piece. During the turns where the primary winding exists, the last primary turn will be covered by the next turn of the insulation. Then a few wrappings of insulation will be made to give the desired isolation for the electrostatic sheild. Next, the electrostatic shield will be fed for one full turn, or whatever greater or lesser amount is to be provided, after which additional turns of insulation material without conductor adjacent thereto will be fed. This is followed by the requisite number of turns for the secondary windings, and wrapping will continue until the desired number'of turns is formed. Thereafter, the external insulation is wrapped in place.

The winding member shown in FIG. 4 includes not only the already-described primary and secondary windings and electrostatic shield, but also a primary capacitance member 88 and a secondary capacitance member 89 which are shown in coded line. As can be seen in FIG. 4, the primary capacitance member occupies one complete turn, as does the secondary capacitance member. This invention comprehends the usage of capacitance members of less than, and more than, one complete turn, and whose width compared to that of the windings is equal to, less than, or greater than, they are. Because these capacitance members are inserted between convolutions of their respective primary and secondary windings, there must be used an additional layer of insulation material in order to receive and insulate the capacitance members from their respective primary or secondary winding. Of course, this additional insulation layer may intermittently be supplied in the same manner as the metal members, should it be desired not to use as much insulation material throughout, but usually it will form a continuous spiral throughout the entire winding member.

The insulation layers are shown as extending throughout, there being two of them, and indicated by arabic numerals 1 and 2. As can best be seen in connection with the primary winding and the primary capacitance member, insulation layer 1 lays next to the mounting member 36, the primary winding lays between it and layer 2, and layer 2 is overlaid by the pri- .mary-c apacitance member, which, on the completion members, meaning that it may be drawn'from either one of reels 67 or 68. It will now be seen that the windings, the electrostatic shield and the capacitance members may be wound together so as to be axially aligned and form the complete contruction of the winding element.

Should the additional primary and secondary impedance members be desired, then at an appropriate time the winding operation will be stopped and a plurality-of flexible metal, preferably soft iron plates, 90 will be laid along the bobbin with their axis of length parallel to its central axis. These plates are best shown in FIG. 7 which illustrates the secondary impedance member. The plates are wrapped around the secondary section 39, and their ends 91 are interleaved. Their free ends may be held down adhesively or by fastener means. Similarly, the primary section will have been laid down against the bobbin before the winding began, and then the winding.will be discontinued for a monent when the primary section is completed, its respective metal leaves similarly assembled, and then the separation section will be formed around it. The illustrated winding device provides a convenient means for making such a construction.

There are, of course, means which can provide the inductance members other than interleaved layers. Rings or other structures which embrace the respective primary or secondary winding are also suitable, so long as they are made of magnetizable material.

Similarly, the utility of the inductance members is not restricted to use with flat foils. This feature can also be used with windings formed from materials of other cross-sections, such as from round wire. While the capacitance members can only be used within flat spirals, the same is not true of the inductance members, which can be used with windings made of materials of any desired cross-section.

FIGS. and 21 illustrate further considerations pertinent to the impedance member. (Throughout the specification and claims, the terms impedance member and impedance means are used interchangeably with inductance member and inductance means). Primary section 37, separation section 38, and secondary section 39 are shown. In FIG. 6, impedance members 40 and 41 embrace all of the turns of their respective sections. In FIG. 21, a secondary impedance member 130 is shown embracing only part of the turns of the secondary-section 39. This same arrangement can be used for the primary impedance member, and, of course, in any embodiment, only one or the other of the impedance elements can be used, instead of both.

Also, the term embrace, as used to define the structural relationship between the impedance member and the turns it embraces, does not necessarily mean total encirclement, although it can, and in FIG. 7 it does. In FIG. 21, the ends 131, 132 form a gap 133 be tween them. Thus, the inductance or impedance of the impedance means can readily be selected as a function of the properties of its material, and by whether a gap is provided, and if so, its size. FIG. 21 also illustrates that the impedance member can be formed by a single plate of magnetizable material such as iron, instead of by a stack. Its ends could be overlapped if desired, as in FIG. 7, instead of forming a gap as shown. Similarly, the stack in FIG. 7 could terminate at a gap (zero or appreciable spacing) instead of an overlapped structure.

As heretofore stated, the attachement of leads to the various sections of conventional transformers has been very troublesome. This disadvantage has been completely overcome in the instant invention by means shown in FIG. Sin which an end 92 of such metallic portion as is being constructed is folded to a 90 bend so as to project laterally sideward of the underlying material, and then is given additional folds 92 (FIG. 9) to form a strong, rugged tab integrally connected without discontinuity to the respective metallic element. The additional folds create at least one dorsal fold 93a and a monolithic self-reinforcing structure results wherein all layers of the folds are mutually interconnected and mutually reinforcing. It is this folded end which is shown as the leads 42-48 in every case.

The folded tabs shown in FIGS. 8 and 9 constritute a most convenient and reliable form of connection to the foil element. There are, of course, other means of connection, for example, by attachment to the foils of conductive adhesive tapes, of clips, soldered bonds or cold-welded joints. Any suitable connector may be used with transformers according to this invention.

FIG. 22 illustrates an elegantly simple means to attach the tabs to other structure. It is simplyan aperture 135 formed continuously through all of the contiguous folded layers. Obviously, thisis a punched hole,

punched after the tab is made. All of the layers serve to reinforce one another, and the construction is surprisingly resistant to tearing out at the hole. By being folded in the manner illustrated, no notches are formed in the foil which could tend to encourage tearing, and the tab is insulated by the adjacent layers of insulating material, except for the portion which extends axially beyond the winding.

The transfonner construction is completed by means of an iron core 96 (FIG. 10), which may be a typical C core construction having two C-sections 97 and 97a. The core passes through the central portion of the winding member. There results a transformer which can readily be wound of simple, lightweight material of minimum envelope dimensions which can have as few or as many turns as desired, which can effectively be shielded, whose electrical members can be connected by integral means, and which can be provided with impedance and/or capacitance means, and with an electrostatic shield. The materials of construction are inexpensive, and, by the use of the mechanism shown in FIGS. 12-15, the cost of manufacturing the transformer is kept to a minimum. 7

The preferred embodiment of this invention involves the winding of all elements into a single roll. This consturction involves fewest parts. However, it is also possible to secure the advantages of this invention in a device which utilizes two winding members, as shown in FIG. 11. In this device, primary winding member and secondary winding member 11 are assembled on a core 112 made of two C shaped halves. Each winding is spirally wound with a respective primary or secondary winding as before, but each has only a primary or a secondary winding. If an electrostatic shield is used, it is formed as a convolution wrapped around the respective winding, so as to shield the winding from electrostatic effects of the other winding. A shield may be placed on only one, or on both, of the windings.

Similarly the capacitance members can be wound into the respective separate Winding member, and also a respective inductance member (not shown) can be wrapped around the same. The import of FIG. 11 is that the advantages of the invention can be secured with the use of more than one winding member.

When the transformer is connected into the illustrated circuit, its primary and secondary winding terminals are connected in the usual manner. The terminal of the electrostatic shield is connected to ground, and the terminals of the capacitance members are connected to respective ones of the terminals of the primary and secondary windings. For other circuits, different connections could be made, for example, the capacitor elements could be connected to ground, and the electrostatic shield to one of the primary or secondary windings. This transformer is a device of broad application, and there are many ways of connecting its elements to other circuitry and to themselves in addition to the arrangement shown in the drawings, which arrangement'i s given by way of illustrating one usage, and not as a limitation on the scope of the invention.

The bulk of the transformer, while about the same as that of conventional transformers, results in a substantial reduction in system bulk and weight, because its performance enables peripheral equipment, such as filters and the like, to be eliminated.

One suitable 125 watt transformer according to the invention utilizes 295 turns in the primary winding, 306 turns in the secondary winding, 1 turn in the electrostatic shield, and 37 turns in each of the capacitance members. It utilizes a stack of thin soft iron plates for each inductance member, the plates being about 0.004 inch thick, with their ends abutted against each other, this being a "zero or minimal gap, but a gap nonetheless. The foil is about 3 inches wide and 0.0005 inch thick. The insulation material is mylar, about 3% inches wide and 0.0002 inch thick. About 200 turns of insulating material isolate the primary winding from the secondary winding.

The terms foil and flat" have been used herein to denote a material which, in the transformer winding element, will be wound turn on turn directly one upon the other. In the usual case, but not in every case, this will dictate the use of relatively thin material of significant width, for example, a thickness less than about 0.050 inch, and a width usually at least about an inch. However, dimensions outside this range may also be used, but without some of the advantages that are inherent within this range.

It is pertinent to notice that, as to the capacitance members 88 and 89, they form one plate of a capacitor, the other plate being the respective primary or secondary winding. Appropriate circuit connections will be made to secure the advantages of this capacitance.

In the case of both the capacitance members and impedance members, the size and extent of the areas confronting the respective windings are the pertinent consideration. FIGS. 16 and 17 illustrate, laid out, one full turn of primary winding 85, and less than one full turn of electrostatic shield 86, whose width is respectively less than and greater than that of the winding material. Arrows 140, 141, 142 indicate the winding direction. In the preferred embodiment, the electrostatic shield extends for at least one full turn, and has a width as great as that of the winding. Then full shielding results, and this could perhaps be improved by making the shield material wider (FIG. 17), although this adds complexity to the manufacture of the winding.

However, substantial electrostatic shielding can be secured with less than full area occlusion by the shield. In fact, a reduction of 20db of noise will be achieved in many transformers with a shield whose length is only of a full turn (or a full turn with a shield of 75% width). The import of this is that one can secure many of the benefits of this invention by only partial shielding, and this is within the scope of the invention.

FIG. 17 shows a shield which is shorter than one turn, and which has a width greater than that of the winding.

The reference to primary or secondary winding in FIGS. 16-21 is applicable to either, those specifically referred to being given only as examples.

FIGS. 18 and 19 shown primary winding and primary capacitance member 88, wound in the insulation member. FIG. 19 shows a laid-out full turn of the primary winding 85, and a primary capacitance member 88 whose length and width are less than those of the turn of the primary winding. Thus, the area of the capacitance member is less than that of the full turn of the primary winding, and, of course, the capacitance is a function of opposed areas. The length of the capacitance member could be greater than one turn, less than one turn, and the width equal to, or greater, or less than that of the winding, the value of all of these variables being selectible to establish the capacitance at a de sired level. Thus, there is no special upper or lower limit on the legth or width of the capacitance members,

other than that it should face an area of its respective winding and provide the proper capacitance.

To summarize, capacitance members and impedance members can be used with either or with both of the primary windings, the area of the electrostatic shield and the capacitance members may be adjusted to achieve a desired effect, and the impedance member may be used with or without overlapping the plate 'or plates, and with an abutment type gap or significantly sized air gap, and embracing all or only part of the turns of the respective winding. 7 i

This invention is not to be limited by the embodiments shown in the drawings and described in the description, which are given by way of illustration and not of limitation, but only in accordance with the scope of the appended claims. j

I claim:

1. A transformer winding member having a central axis, comprising; a spirally-wound layer of flat insulation material forming a spiral and having a dimension of length which is wrapped around the axis, and a dimension of width which extends in the said axial direction, there being a plurality of turns of said material; a primary winding and a secondary winding of flat electrically conductive material having a dimension of length which is wound around the axis, and a dimension of width which extends in the said axial direction which is no greater than the dimension of width of the insulation material, each of said windings comprising at least one full turn; an electrostatic shield of flat electrically conductive material having a dimension of length which is wound around the axis, and a dimension of width which extends in the said axial direction, said windings and shield lying between turns of said insulation material, and being radially spaced from one another by turns of the insulation material, and separated from one another along their dimensions of length, the shield lying between the windings and being axially aligned with at least a portion thereof.

2. A transformer winding member according to claim 1 in which terminal means for said windings and shield comprises and end portion of the material of the respective winding or shield folded to project laterally beyond the winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form the said portion as a monolithic structure.

3. A transformer winding member according to claim 1 in which the primary and secondary windings and their contiguous insulation material respectively comprise a primary and secondary section, theinsulation material between these sections comprises a separation section, there being an impedance means of magnetizable material embracing in a radial plane at least a portion of one of the respective primary and secondary sections.

4. A transformer winding member according to claim 3 in which the said impedance means comprises a metal plate.

5. A transformer winding member according to claim 3 in which said impedance means comprises a plurality of iron plates in a stack, with their ends interleaved.

6. A transformer winding member according to claim 1 in which a capacitance member of flat electrically conductive material is wrapped into the spiral within a winding, being separated therefrom by said insulation means on both of its sides, and being electrically insulated from all other metallic elements of the winding member.

7. A transformer winding member according to claim 6 in which a capacitance member is wrapped into both the primary and secondary windings.

8. A transformer winding member according to claim 6 in which the primary and secondary windings and their contiguous insulation material respectively comprise a primary and secondary section, the insulation material between these sections comprises a separation section, there being an impedance means of magnetizable material embracing in a radial plane at least a portion of one of the respective primary and secondary sections.

9. A transformer winding member according to claim 8 in which the said impedance means comprises a metal plate.

10. A transformer winding member according to claim 7 in which the primary and secondary windings and their contiguous insulation material respectively comprise a primary and secondary section, the insulation material between these sections comprises a separation section, there being an impedance means of magnetizable material embracing in a radialplane at least a portion of only a respective one of the respective primary and secondary sections.

11. A transformer winding member according to claim 10 in which the said impedance means comprises a metal plate.

12. A transformer winding member according to claim 10 in which said impedance means comprises a plurality of iron plates in a stack, with their ends interleaved.

13. A transformer winding member according to claim 6 in which terminal means for said windings and shield comprises and end portion of the material of the respective winding or shield folded to project laterally beyond the winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolithic structure.

14. A transformer winding member according to claim 7 in which terminal means for said windings and shield comprises an end portion of the material of the respective winding or shield folded to project laterally beyond the winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolitic structure.

15. A transformer winding member according to claim 10 in which terminal means for said windings and shield comprises an end portion of the material of the respective winding or shield folded to project laterally beyond the winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolitic structure.

16. In combination: a transformer winding member according to claim 1, and a magnetic core member encircling the same and passing through the center thereof.

17. A combination according to claim 16 in which terminal means for said windings and shield comprises an end portion of the material of the respective winding or shield folded to project laterally beyond the winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolithic structure.

18. A combination according to claim 16 in which the primary and secondary windings and their contiguous insulation material respectively comprise a primary and secondary section, the insulation material between these sections comprises a separation section, there being an impedance means of magnetizable material embracing in a radial plane at least a portion of one of the respective primary and secondary sections.

19. A combination according to claim 16 in which a capacitance member of flat electrically conductive material is wrapped into the "spiral within a winding, being separated therefrom by said insulation means on both of its sides, and being electfiically insulated from all other metallic elements of the winding member.

20. A combination according to claim 19 in which the primary and secondary windings and their contigu-- ous insulation material respectively comprise a primary and secondary section, the insulation material between these sections comprises, a separation section, there being an impedance means of magnetizable material embracing in a radial plane at least a portion of one of the respective primary and secondary sections.

21. A transformer winding member according to claim 1 in which the electrostatic shield extends for at least one full turn, and is at least as wide as the primary and secondary windings.

22. A transfonner winding member according to claim 6 in which the capacitance member extends for at least one full turn.

23. A transformer winding member according to claim 22 in which the electrostatic shield extends for at least one full turn, and is at least as wide as the primary and secondary windings.

24. A transformer winding member having a central axis, comprising: a spirally-wound layer of flat insulation material forming a spiral and having a dimension of length which is wrapped around the axis, and a dimension of width which extends in the said axial direction, there being a plurality of turns of said material; a winding of flat electrically conductive material having a dimension of length which is wound around theaxis, and a dimension of width which extends in the said axial direction which is no greater than the dimension of width of the insulation material, said winding comprising at least one full turn; and electrostatic shield of flat electrically conductive material having a'dimension of length which is wound around the axis, and a dimension of width which extends in the said axial direction, said winding and shield lying between turns of said insulation material, and being radially spaced from one another by turns of the insulation material, and separated fron one another along their dimensions of length, the shield lying outside the winding and being axially aligned with at least a portion thereof.

25. A transformer winding member according to claim 24 in which the width of theelectrostatic shield is at least as great as the width of the winding.

26. A'transformer winding member according to claim 24 in which terminal means for said winding and for said shield comprises an end portion of the material of the respective winding or shield folded to project laterally beyond the'winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolilthic structure.

27. A transformer winding member according to claim 24 in which impedance means of magnetizable material embraces in a radial plane at least a portion of the winding. I

28. A transformer winding member according to claim 27 in which the'said impedance means comprises a metal plate. i

29. A transformer winding member according to claim 27 in which said impedance means comprises a plurality of iron plates'in a stack, with their ends interleaved.-

30. A transformer winding member according to claim 27 in which'saidimpedaneemeans comprises a metal plate *whose'ends are spacedapart by a gap.

31. A transformer-winding member according to claim 24 in which a capacitance member of flat electrically conductive material is wrapped into the spiral within the winding, being separated therefrom by said insulation means on both of its sides, and being electrically insulated from all other metallic elements of the winding member.

32. A transformer winding member according to claim 31 in which impedance means of magnetizable material embraces in a radial plane at least a portion of the winding.

'33. In combination: a pair of transformer winding members according to claim 24, and a magnetizable metallic core member extending through a central axial opening in both of said transformer winding members.

34. A combination according to claim 33 in which terminal means for said winding and for said shield comprises an end portion of the material of the respective winding or shield folded to project laterally beyond the winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolithic structure. 7

35. A combination according to claim 33 in which impedance means of magnetizable material embraces 16 in a radial plane at leastaportion of one of said winding sections. Y

36. A combination according to claim 33 in which a capacitance member of-flat electrically conductive material is wrapped into the spiral of at least one of the winding members, and being separated therefrom by said insulation material on both of its sides, and being electrically insulated from all other metallic elements of the winding member.

37. A combination according to claim 36 in which impedance means of magnetizable material embraces in a radial plane at least a portion of one of said winding sections.

38. A transformer winding member having a central axis, comprising: a spirally-wound layer of flat insulation material forming a spiral and having a dimension of length which is wrapped around the axis, and a dimension of width which extends in the said axial direction, there being a plurality of turns of said material; a primary winding and a secondary winding of flat electrically conductive material having a dimension of length which is wound around the axis, and a dimension of width which extends in the said axial direction which is no greater than the dimension of width of the insulation material, each of said windings comprising at least one full turn; said windings lying between turns of said insulation material, and being radially spaced from one another by turns of the insulation material and separated from one another along their dimensions of length; and an impedance means of magnetizable material embracing at least a portion of only a respective one of the windings in a radial plane. I

39. A transformer winding member according to claim 38 in which the said impedance means comprises a metal plate.

40. A transformer winding member according to claim 39 in which a gap is formed between the ends of the plate. I i

41. A transformer winding member according to claim'38 in which said impedance means comprises a plurality of iron plates in a stack, with their ends interleaved.

42. A transformer winding member having a central axis, comprising: a spirally-wound layer of flat insulation material forming a spiral and having a dimension of length which is wrapped around the axis, and a dimension of width which extends in the said axial direction, there being a plurality of turns of said material; a primary winding and a secondary winding of flat electrically conductive material having a dimension of length which is wound around the axis, and a dimension of width which extends in the said axial direction which is no greater than the dimension of width of the insulation material, each of said windings comprising at least one full turn, said windings lying between turns of said insulation material, and being radially spaced fron one another by turns of the insulation material, and separated from one another along their dimensions of length; and a capacitance member of flat electrically conductive material wrapped into the spiral within a respective winding being separated therefrom by said insulation material on both of its sides, and being electrically insulated from all other metallic elements of the winding member. I j

43. A transformer winding member according to claim 42' inwhich terminal means for said windings and capacitance member comprises an end portion of the respective winding or capacitance member folded to project laterally beyond the winding member, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolithic structure.

44. A transformer winding member according to claim 43 in which an aperture is formed continuously through the folded portion.

45. In a wound transformer winding wherein metallic foil material is utilized as a conductor, a terminal for said winding comprising an end portion of said foil material folded to project laterally beyond the transformer winding, the projecting portion being multiply folded, whereby to form a plurality of dorsal folds extending longitudinally along the projecting portion to form a monolithic structure to provide a conductive connection for said conductor.

46. Structure according to claim 45 in which an aperture is formed continuously through the folded portion.

47. A transformer winding according to claim 4 in which a gap spaces apart the ends of the metal plate.

48. A transformer winding member according to claim 2 in which an aperture is formed continuously through the folded portion.

49. A combination according to claim 17in which an aperture is formed continuously through the folded portion.

50. A combination according to claim 34 in which an aperture is formed continuously through the folded portion.

51. A transformer winding member according to claim 42 in which a capacitance member is wrapped in each of the primary and secondary windings.

52. A combination according to claim 19 in which a capacitance member is wrapped in each of the primary and secondary members.

53. In a wound transformer having a plurality of windings, an impedance member respective to only one of said windings comprising a body of magnetizable material embracing in a radial plane at least a portion of only that winding.

54. Apparatus according to claim 53 in which the impedance member is a metal plate.

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Classifications
U.S. Classification361/270, 336/192, 336/223
International ClassificationH01F41/06, H01F27/33, H01F27/34, H01F41/10, H01F27/38, H01F27/32
Cooperative ClassificationH01F41/0608, H01F27/33, H01F27/323, H01F41/10, H01F27/38
European ClassificationH01F27/38, H01F41/06A1, H01F41/10, H01F27/32C, H01F27/33