US2266925A - Electrical coil - Google Patents

Description

Dec. 23, 1941.

c. w. VERRIL L ELECTRICAL COIL Original Filed Jan. 15, 1939 wmvrm C. W Vffi/P/ZL 2% v Aime/v0" Patented Dec. 23, 1941 ELECTRICAL COIL Charles W. Verrill, Hinsdale, Ill., assignor to Western Electric Company, Incorporated, New

York, N. Y.,

a corporation of New York Original application January 13, 1939, Serial No.

Divided and t his application August 17, 1940, Serial No. 353,081

7 Claims.

This invention relates to electrical coils and more particularly to spool wound electrical coils, and is a division of my earlier rial No. 250,761, filed January 13, 1939, and now Patent No. 2,216,464, dated October 1, 1940.

In the manufacture of spool wound electrical coils, particularly of enamel insulated wire, it is the practice, in some instances, to connect a bare lead wire to a bare end of enamel insulated wire preliminary to starting the winding of the coil. The portion of the lead wire extending from the inner face of an insulating washer at the spool head to the bare end of the insulated wire is covered with an insulating element to prevent the adjacent layers of enameled winding wire from working or being pressed downwardly along the inner face of the washer into contact withthe bare lead wire, which condition may result in portions of the enamel becoming removed from the winding wire, thus short circuiting one or more layers of the coil. One insulating element heretofore used has been made from celanese silk treated to stiffen and improve its insulating qualities. Such material is not only expensive in its first cost, but it requires subsequent treating, and due to its nature, even after treatment, is difilcuit to handle and thus a high degree of care and skill is required to apply it in the winding of the coil,

An object of this invention is to provide an electrical coil of the above described type having improved means for insulating the uninsulated lead wire from the winding wire.

In order to attain this object, in accordance with the features of one embodiment of the invention, as applied to spool wound electrical coils, an initially flat insulator is provided which is formed from cellulose acetate strip material folded adjacent one longitudinal edge to provide a double flat fold which is appreciably spaced from the opposite edge of the sheet, the several thicknesses of material being coalesced by applying colored acetone to a series of perforations formed in the folded material and extending along the length of the fold, the colored acetone seeping between the folds, coalescing the several thicknesses of material and producing a colored line. The single thickness of material extending from one edge of the fold to the adiacent edge of the sheet is serrated to permit it to readily flex and form an outwardly directed flange at the annular corner or juncture of the inner face of the coil head washer and a core of the coil while the single thickness of material extending from the opposite edge of the application, Se

fold to the other edge of the sheet is wrapped around the connected ends of the lead and winding wires. The fold adjacent the serrated edge serves as a reinforcement and stiffener for the insulator which is effective to prevent the single thickness of thin cellulose acetate material from tearing through the fold and also to facilitate the handling of the insulator. In applying the insulator in the winding of a coil the colored line indicates to the operator which edge of the insulator is serrated and thus facilitates the application thereof to the coil. The fold is applied at the annular comer and thus the several thicknesses of material provide increased insulation thereat.

A complete understanding of the invention may be had from the following detailed description taken in conjunction with the appended drawing, in which -Fig. 1 is an elevational view of a completed electrical coil embodying the invention;

Fig. 2 is an enlarged longitudinal vertical sectional view of the left end of the coil shown in Fig. 1;

Fig. 3 is an enlarged perspective view of the left end of the coil shown in Fig. 1 illustrating the coil before it is completely wound, and the improved insulator applied thereto;

Fig. 4 is an enlarged plan view of the insulator before being applied to the coil, and

Fig. 5 is an enlarged vertical section taken on the line 5-5 of Fig. 4.

Referring now to the drawing, Figs. 1 and 2, one embodiment of an electrical coil embodying the features of the invention is shown in the form of a spool wound electrical coil ill of the type used'extensively for relays and other electrical apparatus. The coil l0 comprises a spool having a core i2, usually made of a soft magnetic metal or alloy and a spool head I! or flange, generally made of fibre or other non-conducting material rigidly secured at each end of the core.

To eflfectively insulate the metal core l2 from the subsequently applied winding the section of the core between the heads I3 is covered with a sheet ll of cellulose acetate or other material having satisfactory dielectric properties. A split disk or washer i5 (Fig. 2) preferably made of cellulose acetate is placed around the core I! and abutted against the inner face of each spool head l3. The washer I! has a central particularly aperture conforming with the contour of the insulating sheet I! surrounding the core and a from the inner face of the flange I6 extending end of the lead wire 7 the core for washer and over the core insulating sheet II for a short distance.

Preparatory to the winding of the coil lo a suitable length of bare stranded terminal or lead wire I9 is connected at its inner end to the uninsulated inner end of enameled insulated winding wire 20, by either soldering the ends together or in any suitable manner, as indicated at 2|. The outer end of the stranded lead wire I9 is then passed through aperture 22 formed in the head l3 andwasher l5 adjacent the periphery of the core l2. Thereafter, the inner I9 is spirally wrapped around a few turns, as shown at 23 (Figs. 2 and 3), and a second split disk or washer 23 of suitable insulating material and provided with a central aperture 21 adapted to freely surround the stranded lead wire turns 23 is placed on the core and pressed toward the spool head l3 and washer l5, the length of the lead wire l9 between th'eaperture 22 of the washer l5 and the core being held between the opposed faces of the two washers.

'Before the actual winding of the coil a member of insulating material is wound around the few turns 23 of the stranded bare lead wire I! and its connection 2| to the winding wire 23 'to prevent,'as hereinbefore described, the subsequently wound adjacent layers of enameled winding wire from working or being pressed downwardly into contact with the bare lead wire with the possibility of short circuiting one or 7 more layers of the coil.

One form of an interleaving insulator 30 by the use of which the above difilculty is overcome is shown in detail in Figs. 4 and 5. This applying the insulator 30 sheet material of insulator is preferably made'from cellulose acetate or a similar non-fibrous material having satisfactory dielectric properties. .In producin the insulator 30 a sheet of cellulose acetate strip material of a suitable width and which is relatively thin is formed with a longitudinally extending flat double fold as indicated at 3|, the longitudinal edges of the fold being parallel vto and spaced-from the corresponding edges of the sheet. The several thicknesses of material comprising the flat fold 3| are coalesced by first forming a series of perforations 32 in two adjacent layers thereof, thelperforations extending longitudinally along and intermediate opposite edges of the fold and thereafter applying acetone to the perforations by suitable means, for instance, by drawing a fountain pen therealong. The acetone seeps through the perforations and between the layers of folded material and firmly secures the several layers together. In the present embodiment colored acetone is preferably used which produces a colored line 33 of appreciable width along the length of the fold 3| for a purpose which will be presently referred to. An edge portion 34 of the sheet extending from one edge thereof to the adjacent edge of the fold 3| is relatively narrow as compared to an edge portion 35 extending from the opposite edge of the fold to the corresponding edge of the sheet. Formed in and along the length of the narrow' edge portion 34 are a series of serrations 31 i which extend from the outside edge of the portion to substantially the adjacent edge of the fold 3|. I

The insulator 30 is applied to the connected lead and winding wires l9. and, respectively, by placing the serrated edge portion 34 at the annular corner or juncture of the inner face of the washer 26 and the insulated core l2 and wrapping it around the connected wires, the insulator being of such a length that several thicknesses thereof may be applied. The fold is placed at the annular corner or juncture of the inner face of the coil head washer 23 and the core cover l4, thus providing increased insulation at this point. Due to the serrations 31 and the single thickness of material extending from the outer edge of the portion 34 to the adjacent edge of the fold 3| the edge portion 34 will readily flex adjacent the edge of the fold and form an outwardly directed flange lying closely against the face of the head washer 26.

The colored .line 33 hereinbefore described, along 4 I the fold 3| is very useful to an operatordn since the line, which is relatively close to the serrated edge portion 34, readily indicates which edge portion is serrated and thus in picking an insulator from a supply and carrying it to the coil being wound it will.

be clearly apparent to the operator which edge portion is to be placed against the washer 23. The edge portion 35 is of such width that it will completely form an insulating cover for the several turns of uninsulated lead wire l9 audits connection 2| to the winding wire 20.

Due to the thinness which the insulator is made, it would be easily tearable, particularly at its serrated edge portion 34, during the handling thereof in applying it to the coil, if not reinforced by the fold 3| which effectively prevents tearing thereof. Furthermore, the fold 3| serves to stiffen the insulator, thus making it easier to handle and apply, and also provides increased insulation at the annular corner of the head and core.

The winding of the coil is then continued in the usual manner and the outer end of the winding wire 20 connected to a stranded terminal or lead wire 40 and a few turns of the lead wire and connected winding wire are taken around the body of the coiled wire, the turns of wire being enclosed in a suitable insulator 4|. Thereafter, the outer end of the lead wire 40 is threaded through apertures in the washers 28 .and I5 and the head I3 and an outer insulating cover 42 is applied.

It will be understood that the nature and embodiment of the invention herein described is merely illustrative and that many changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. An'electric coil comprising a core with a head, an insulated winding on said core, a lead connected at itsinner end to said winding adjacent the inner face of the head and extending outwardly thereof, and an insulator element covering the connection of said lead wire to said winding and extending outwardly at the annular corner of the inner face of the head and surrounding said core, said insulator comprising a sheet of non-fibrous insulating material having a fold spaced from an edge portionfor preventing tearing of the sheet pastthe fold, said edge portion adapted to readily flex outwardly from an edge of the fold during the application of the insulator to the coil, said fold edge being applied at said annular corner.

2. An electrical coil comp ing a core with a of the cellulose acetate outwardly thereof, and an insulator element covering the connection of said lead wire to said ering the connection of said lead wire to said winding and extending outwardly at the annular winding and extending outwardly at the annular corner of the inner face of the head and said corner of the inner face of the head and surcore, said insulator comprising a sheet of cellurounding said core, said insulator comprising a 5 lose acetate material having a flat fold spaced sheet of non-fibrous insulating material having a from an edge of the sheet, said fold preventing fold extending along an edge portion of the sheet tearing of the sheet past the fold, the edge of the with the folded material secured together, said sheet having a series of serrations extending fold preventing tearing of the sheet past the toward the fold for permitting the edge portion fold, said edge portion adapted to readily flex to readily flex adjacent an edge of the fold duroutwardly from an edge of the fold during the ing the application of the insulator, said fold beapplication of the insulator to the coil, said fold ing applied at said annular corner. edge being applied to said annular corner. 6. An electric coil comprising a core with a 3. An electric coil comprising a core with a head, an insulated winding on said core, a lead head, an insulated winding on said core, a lead connected at its inner end to said winding adconnected at its inner end to said winding adjacent the inner face of the head and extending jacent the inner face of the head and extending outwardly thereof, and an insulator element covoutwardly thereof, and an insulator element ering the connection of said lead wire to said covering the connection of said lead wire to said winding and extending outwardly atthe annular winding and extending outwardly at the annular 2o corner of the inner face of the head and said corner of the inner face of the head and said core, said insulator comprising a sheet of cellucore, said insulator comprising a sheet .of nonlose acetate material having a double fold of fibrous insulating material having a fold extendthree thicknesses of material extending longiing longitudinally thereof and spaced from an tudinally thereof and spaced from an edge 'of edge of the sheet for preventing tearing of the 5 the sheet, two adjacent thicknesses of material sheet past the fold, said edge of the sheet having of the fold having a series of perforations, and a series of serrations extending toward the fold acetone within said perforations for coalescing for permitting the edge portion to readily flex the three thicknesses of folded material, said outwardly from an edge of the fold during the fold preventing tearing of the material past the application of the insulator to the coil, said fold fold, said edge portion adapted to readily flex edge being applied at said annular corner. outwardly from an edge of the fold during the 4. An electric coil comprising a core with a application of the insulator to the coil, said fold head, an insulated winding on said core, a lead edge being applied at said annular corner. connected at its inner end to said winding ad- 7. An electric coil comprising a core with a Jacent the inner face of the head and extending head, an insulated winding on said core, a lead outwardly thereof, and an insulator element connected at its inner end to said winding adcovering the connection of said lead wire to said jacent the inner face of the head and extending winding and extending outwardly at the annular outwardly thereof, and an insulator element covcorner of the inner face of the head and said ering the connection of said lead wire to said core, said insulator comprising a sheet of celluwinding and extending outwardly at the annular lose acetate material having a fold extending corner of the inner face of the head and said longitudinally thereof and spaced from an edge core, said insulator comprising a sheet of celluof the sheet, several thicknesses of materialpf lose acetate material having a flat double fold the fold having a series of perforations, and aceof three thicknesses of material spaced from an tone within said perforations for coalescing the edge of the sheet, two adjacent thicknesses of folded material, said fold preventing tearing of material of the fold having a series of perforathe material past the fold, said edge portion tions, and acetone within said perforations efadapted to readily flex outwardly from an edge fective to coalesce the three thicknesses of maof the fold during the application of the insulaterial, said edge of the sheet having a series of tor to the coil, said fold edge being applied at 5 parallel serrations extending toward the fold for said annular corner. permitting the edge portion to readily flex adja- 5. An electric coil comprising a core with a cent an edge of the fold during the application head, an insulated winding on said core, a lead of the insulator to the coil, said fold edge being connected at its inner end to said winding adapplied at said annular corner. jacent the inner face of the head and extending outwardly'thereof, and an insulator element cov- CHARLES W. VERRILL.

Images