US3131372A - Coil leads insulating and securing means - Google Patents

Description

April 28, 1964 s. CALTAGIRONE COIL LEADS INSULATING AND SECURING MEANS Filed March 20, 1961 n @w g; m w 92 m% r support for the coil.

United States Patent 3,131,372 C(ltilL LEADS INSULATING AND SlECUlilNG MEANS Saverio Caltagirone, Danvilie, Iii, assignor to General Electric Company, a corporation of New York Filed Mar. 20, 1961, Ser. No. 97,081 7 Claims. (Cl. 336-192) This invention relates to electrical coil assemblies and methods of manufacture thereof. More particularly, the invention relates to electrical coil assemblies having windings wherein conductors are brought out from the margins of the coil assembly and to methods of manufacture thereof.

Electrical coil assemblies generally used in transformers such as ballast transformers employ one or more windings which are wound on a spool in successive layers between which insulating layers are interposed. Where the individual winding is a filament heating winding, the individual winding may require only several turns. However, where the individual winding to be connected in a ballast circuit is a secondary winding, a relatively large number of turns may be required. In such a case, it is required that a conductor such as the start conductors be brought out from the coil margins to the outside wrapper of the coil in order that connections can be made to the conductor. It is the usual practice to bring the conductor out to connectors on the outside wrapper where the conductors can then be soldered to external circuit leads or other coil conductors. Because the conductor is brought out along the margins where it can readily come in contact with the winding itself, an adjacent coil or a magnetic shunt, it is required that the conductor be provided with under insulation to insulate the underside of the conductor from the coil assembly and over insulation to insulate the outer side of the conductor.

Although not limited thereto, the coil assembly arrangement of the present invention is particularly adaptable to coil assemblies having coils which are multiple wound on a paper spool with paper layer insulation interleaved between each wire layer. The paper spool serves the double function of insulating the coil from the magnetic core of a transformer and also providing The paper insulation interleaved between layers of the wire is required in order to keep each layer of wire flat and to insulate the wire layers from each other. The paper insulation also prevents rubbing between the layers of wire. Such rubbing would eventually damage the wire insulation and cause a short circuit.

Electrical coils of the type described herein are generally multiple-wound on a continuous spool. After the winding operation is completed, a wrapper is applied on the top of the last layer of wire and saw marks are made on the strip to indicate the point at which the individual coils are to be sliced. After the individual coils are sliced, the start and finish conductors are pulled out of the margin and finished off. Since the finishing operation is done by hand, it is desirable that the conductors be finished ofl quickly and easily. The finishing operation includes the application of over and under insulation for certain conductors.

A common method used in the past required the application of two substantially rectangular shaped gummed insulating pieces of paper to a conductor to insulate it. According to this method of assembly, the first piece was wetted on its gurnmed side and placed into the margin of the coil in front of the coil conductor. It was then bent over the margin and glued to the coil body. A second insulating piece was placed into the coil margin over the first piece and over the conductor. It was bent over the first piece and [glued to it in order to provide the over insulation for the conductor and firmly position the coil conductor. One of the disadvantages of this prior art method was that it required that two separate insulating pieces be applied in order to provide over and under insulation for a coil conductor. One of the difficulties encountered with the two insulating piece arrangement was that the outer insulating piece often worked loose or became sufficiently loose to permit the coil conductor to slip out. There is a need, therefore, for a conductor insulating arrangement wherein the over and under insulation can be readily'applied and wherein the coil conductor can be effectively retained .in place and insulated.

Accordingly, it is the general object of the present invention to provide a core assembly having an improved means for insulating the conductors brought out from a coil.

it is another object of the invention to provide a coil assembly that can be readily assembled and that utilizes a minimum number of pieces.

A more specific objection of the invention is to provide an improved coil assembly having an improved conductor insulating and securing means whereby a conductor brought out from the coil is effectively insulated.

Another object of the invention is to provide an improved method for applying over and under insulation for coil conductors brought out from a coil.

in one form of the invention 1 have provided an electrical coil assembly comprising a winding formed of plurality of wire layers and insulating layers interleaved therebetween, the winding having at least a start. conductor and a finish conductor. An insulating tab is provided for at least one of said conductors and it is formed with a pair of attaching portions and over an under insulating portions. The under insulating portion is folded under the conductor and attached to the over insulating portion so the conductor is firmly engaged between the insulating portions.

One of the attaching portions is secured to the coil underside and the other attaching portion is secured to the coil wrapper or other portion of the coil where the conductor is to be connected in circuit. Preferably, the coil conductor is positioned in the corner fold formed by folding the under insulating portion under the over insulating portion.

According to the method of the present invention, the under insulating portion of the insulating tab is folded over a coil conductor and glued to the over insulating portion of the insulating tab so that the coil conductor is firmly secured between the over and under insulating portions and is brought out at the corner fold of the under insulating portion of the tab so that the coil conductor is retained in position by the corner fold and the glued surfaces of the under and over insulating portions.

The subject matter which I regard as my invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. My invention, however, both as to organization and method of opera tion, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:

PEG. 1 is a partially sectionalized view of a coil assembly with a portion of the spool cut away to show the start anchor strip and a coil conductor brought out from the under side of the coil;

FIG. 2 is a view of the coil assembly corresponding to the view shown in FIG. 1 in which the insulating tab is shown in position prior to assembly with the under insulating portion partially folded over;

FIG. 3 is a perspective view of the insulating tab partially folded over showing the gummed underside of the insulating tab;

FIG. 4 is another sectionalized view of the coil assembly wherein a portion of a spool is cut away to show the insulating tab in assembled relation with the coil assembly;

FIG. 5 is a sectionalized view taken along line 5--5 of the coil assembly shown in FIG. 4;

FIG. 6 is a perspective view of the coil assembly in accordance with the invention showing the insulating tab in assembled relation with the coil assembly and having a part of the coil wrapper cut away to show the finish conductor anchor strip;

FIG. 7 is a fragmentary view of the back side of the coil assembly shown in FIG. 6 illustrating the manner in which the insulating tab is attached to the coil wrapper and the start conductor is engaged by the fold formed by the over and under insulating portions; and

FIG. 8 illustrates a continuous gumrned strip from which the insulating tabs may be cut without scrap.

Referring now to the drawing, I have illustrated therein an electrical coil assembly 9 having winding formed of a plurality of wire layers 12 wound on a spool 15 Interleaved between the wire layers are a plurality of insulating layers 13. The insulating layers 13-5 are interposed between the wire layers 12 so that movement between adjacent wire layers 12 will not cause wear of the Wire insulation and cause short circuits to occur in the coil.

In the embodiment of the invention illustrated in the drawings, the coil assembly 9 is provided with a start conductor 14 and a finish conductor 15, which are held in position by anchor strips 16, 17. Anchor strips 16, 17 are provided so that the coil conductors 14, 15 brought out from the coil assembly 14) are firmly secured to the coil assembly and so that a conductor layer is not pulled out as tension is applied to conductors 14, 15.

The anchor strip 16 for the start conductor 14 is best seen in the views of the coil assembly 9 shown in FIGS. 1 and 2 while the finish anchor strip 17 for the finish conductor 15 is best seen in the view shown in FIG. 6. In FIG. 1 anchor strip 16 is shown in imaginary outline withdrawn from coil assembly 9 where it is interposed between the spool and lowermost wire layer 12.

Although preferably the coil conductors 14, are anchored in position on coil assembly a by the use of anchor strips 16, 17, it will be appreciated that the coil conductors 14, 15 may be anchored by other suitable means such as by securing the coil conductor to the coil layer by cloth adhesive tape as is frequently done in the manufacture of electrical coils. Anchor strips are preferably employed since rnore uniform radial dimensions of the coil can be maintained. Cloth anchor tape frequently bunches up during assembly and thereby introduces a high spot. An advantage achieved by the use of an anchor strip is that the start and finish conductors of a coil assembly may be more accurately positioned. As shown in FIG. 1, when the coil conductor 14 is pulled out and caught in the conductor positioning slot 11 provided in the anchor strip, it is precisely positioned at a fixed axial distance from the end of the coil assembly 9.

Layer insulation is continuously wound with wire layers 12; so that the insulation layers 13 are interleaved between wire layers 12. Preferably, the layer insulation may be formed of thin paper since it has good dielectric properties and is a relatively inexpensive material. The spool 10 may also be formed of paper and with a rectangular opening that conforms to the cross sectional configuration of the magnetic core leg (not shown) on which the coil assembly 9 will be mounted. Thus, the spool 10 disposed at the underside of the coil assembly 9 serves the purpose of insulating the wire layers 12 from the magnetic core and also serves 'as a support member for the coil assembly 9. An outer wrapper 18, preferably of kraft paper, is provided over the outer wire layer and serves as a protective covering for the coil assembly 9.

It will be understood that during manufacture a plurality of windings are wound at one time on a continuous spool which is mounted on an arbor. Wherever a conductor is to be brought out from the coil, a continuous anchor strip having a plurality of anchor slots is positioned so that the wires are engaged in individual slots. A few turns of wire are wound on the spool, and these additional turns provide the amount of lead required for a particular conductor. The outer Wrapper is then applied on the spool and the entire spool is sliced into individual coils. After the slicing operation is completed, individual conductors are pulled out. Thus, the coil assembly 9 shown in FIG. 1 represents an individual coil that has been sliced off and is ready for the conductor finishing operation and assembly in accordance with the invention.

Referring now to FIG. 2, it will be seen that an insulating tab 19 is shown in partially assembled relation with the coil assembly 9. The insulating tab 19 is formed with an upper attaching portion 29, a lower attaching portion 21, an over insulating portion 22 and an under insulating portion fiap 23. One side of the insulating tab is gummed, so that it can be made to readily adhere to the coil assembly h, as is shown in FIG. 3.

In the illustrative embodiment of the invention, I have employed a lower attaching portion 21 which is slightly shorter in length than the upper attaching portion 20. As shown in FIG. 2 the lower attaching portion 21 is inserted between the coil underside and the coil spool 10 so that the gummed side of attaching portion 21 adheres to the coil underside. If desired, the attaching portions 20, 21 may be substantially equal in length.

In FIGS. 4, 5, 6 and 7, I have shown the insulating tab 19 in final assembled relation with the coil assembly 9. it will be seen that the attaching portion 21 of insulating tab l9 is inserted between the spool 19 and the anchor strip 16 so that the gummed side of attaching portion 21 adheres to the anchor strip 16. Attaching portion 2t) is bent over and the glued underside adheres to the coil wrapper 18. Having more specific reference to the cross sectional view of the portion of the coil assembly 9 shown in FIG. 5, it will be noted that the under insulating portion 22 is interposed between the conductor 14 and the wire layers 12. The under insulating portion 23 is folded under the over insulating portion 22 and start conductor 14 is securely sandwiched between the glued surfaces of the over insulating portion 22 and under insulating portion 23.

Heretofore, over and under insulation for a coil conductor was provided by using two substantially rectangular shaped gumrned pieces. The first gummed piece was attached at one end to the underside of the coil, the coil side and at the other end to the coil wrapper. This first piece provided the under insulation for the coil conductor. The conductor was placed over the first piece. The second gummed strip was then placed over the conductor and glued to the first piece. The arrangement according to the present invention provides very significant advantages over such prior art methods of manufacture. In accordance with the insulating tab arrangement of the invention, the insulating tab 19 is securely attached to coil assembly 9 in a one step finishing o e ation. The under insulating portion 23 is simply folded over the coil conductor 14 as shown in FIG. 2. The lower attaching portion 21 is inserted between the coil underside and coil spool 10 with the gummed side facing the coil underside to which it attaches. The upper attaching portion 20 is bent over with the gummed side overlying the coil wrapper 18. Thus, the gummed side of the attaching portion 2% adheres to the coil wrapper 18. Therefore, it is only necessary to handle a single piece in the manual assembly operation and the finishing operation can be accomplished by simple manipulation of the insulating tab 19. Further, the arrangement of the invention provides the advantage that the under insulating portion 23 is integrally a part of the over insulating portion 22 and the coil conductor 14 is thereby securely positioned between two glued surfaces.

In many applications, the wire used for a coil winding is often hair-thin in size. Where separate insulating pieces are used to provide over and under insulation for a coil conductor, the hair-thin wire may cause the glued pieces to separate as tension is applied to the conductor due to the shearing action of the wire. As is best seen in the view shown in FIG. 7, the start conductor 14 is preferably brought out so that it engages the corner fold that is formed when the under insulating portion 23 is folded under the start conductor 14. With this arrangement, start conductor 14 is firmly secured and tension applied to the coil conductor 14 will not readily cause the glued portions of the insulating tab 19 to separate since conductor 14 is engaged against the corner fold.

Since outer and inner insulating portions 22, 23 are glued together by two gummed surfaces, it will be apparent that where two gummed surfaces are joined, the surfaces are less likely to separate than where one gummed surface is joined to another which is not glued. Thus, even if the attaching portions 22, 23 of the insulating tab 19 separate from the coil assembly 9, the conductor 14 is still retained in position between the over and under insulating portions 22, 23.

It will be understood that while I have illustrated my invention by a specific embodiment thereof, many modifications rnay be made by those skilled in the art without departing from the invention. T bus, the configuration of the insulating tab and the manner of attachment to the coil assembly may be varied. It is, therefore, intended in the appended claims to cover all such appended claims to cover all such equivalent variations that face within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electrical coil assembly comprising a winding formed of a plurality of wire layers, a plurality of insulating layers interposed between said wire layers, at least one coil conductor brought out from one of said wire layers, means for anchoring said coil conductor to said coil assembly, a coil Wrapper encompassing the outer wire layer and providing an insulating and protective covering for said layer, and an insulating tab having one gummed side and having a pair of attaching portions and over and under insulating portions, one of said attaching portions securing said insulating tab at said gummed side to the coil underside and the other of said attaching portions securing the insulating tab at said gummed side to the coil wrapper, said under insulating portion providing insulation between said coil conductor and said winding and said over insulating portion providing insulation for the outer side of saidcoil conductor, said under insulating portion being integrally formed with said over insulating portion and beind folded over under said coil conductor to engage the coil conductor therebetween and securely position the coil conductor on the coil wrapper.

*2. The electrical coil assembly as set forth in claim 1, wherein the coil conductor is positioned against the corner fold formed by the under and over insulating portions of said insulating tab.

3. In an electrical coil assembly formed of a plurality of wire layers having insulating layers interleaved theretom wire layer of said coil assembly to the outer portion thereof, an insulating tab having one side completely gummed, an over insulating portion folded over said coil conductor and an under insulating portion folded under said conductor and attached to said over insulating portion at the gummed side thereof, said insulating tab having between and a start conductor brought out from the bota pair of attaching portions one of said attaching portions being secured at the gummed side to the coil underside and the other attaching portion being secured at the gummed side to an outer portion of said coil assembly.

4. An electrical coil assembly comprising a spool, a winding wound in a plurality of wire layers on said spool, a plurality of insulating layers interleaved between said wire layers, a start anchor strip disposed between said spool and a wire layer, said anchor strip being formed with a conductor positioning slot, a coil conductor engaged in said conductor positioning slot of the anchor strip and brought out from said winding to provide a terminal connection for said winding, an insulating tab having a pair of attaching portions, one of said attaching portions being connected to said anchor strip and the other of said attaching portions being connected to an outer portion of said coil assembly, said insulating tab having an under insulating portion folded under the coil conductor so as to provide insulation between the coil conductor and the winding, and said insulating tab having an over insulating portion folded under the coil conductor and attached to said over insulating portion to securely engage said coil conductor and to insulate the outer side thereof.

5. The electrical coil assembly as set forth in claim 4 wherein the coil conductor is positioned against the corner fold formed by the under and over insulating portions of said insulating tab.

6. An electrical coil assembly comprising a spool, a winding wound in a plurality of wire layers on said spool, a coil wrapper encompassing the outer wire layer and provide an insulating and protective covering for said layer, at least one coil conductor brought out from said winding to provide a terminal connection for said winding and an insulating tab having one gummed side and having a pair of attaching portions, one of said attaching portions being attached at said gummed side within the coil and the other of said attaching portions being attached at said gummed side to said coil wrapper of said coil assembly, said insulating tab having an under insulating portion folded under the coil conductor so as to provide insulation between the coil conductor and the winding, and having an over insulating portion folded over the coil conductor and joined to the gummed side of said under insulating portion thereby insulating the outer side of said conductor.

7. The electrical coil assembly as set forth in claim 6, wherein the coil conductor is positioned against the corner fold formed by the under and over insulating portions of said insulating tab.

References Cited in the file of this patent UNITED STATES PATENTS 1,752,866 Trombetta Apr. 1, 1930 2,122,894 Sager July 5, 1938 2,159,269 Hasse May 23, 1939 2,264,832 Ensign Dec. 2, 1941

Claims (1)

1. 3. IN AN ELECTRICAL COIL ASSEMBLY FORMED OF A PLURALITY OF WIRE LAYERS HAVING INSULATING LAYERS INTERLEAVED THERETOM WIRE LAYER OF SAID COIL ASSEMBLY TO THE OUTER PORTION THEREOF, AN INSULATING TAB HAVING ONE SIDE COMPLETELY GUMMED, AN OVER INSULATING PORTION FOLDED OVER SAID COIL CONDUCTOR AND AN UNDER INSULATING PORTION FOLDED UNDER SAID CONDUCTOR AND ATTACHED TO SAID OVER INSULATING PORTION AT THE GUMMED SIDE THEREOF, SAID INSULATING TAB HAVING BETWEEN AND A START CONDUCTOR BROUGHT OUT FROM THE BOTA PAIR OF ATTACHING PORTIONS ONE OF SAID ATTACHING PORTIONS BEING SECURED AT THE GUMMED SIDE TO THE COIL UNDERSIDE AND THE OTHER ATTACHING PORTION BEING SECURED AT THE GUMMED SIDE TO AN OUTER PORTION OF SAID COIL ASSEMBLY.

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