US1878606A - Coil construction - Google Patents

Description

Sept. 20, 1932. w Q SCHNE|DER ETAL 1,878,606

con. CONSTRUCTION Filed July 20. 1928 Inventor/a Fil 1 FE1-L Hark/won Patented Sept. 20, 1932 UNITED STATES PATENT OFFICE WILLIAM G. SCHNEIDER AND HARRISON H. EATON, OF TOLEDO, OHIO, ASSIGNORS TO THE ELECTRIC AUTO-LITE COMPANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO i COIL CONSTRUCTION Application led July 20, 1928. Serlal No. 294,143.

This invention relates to induction coils and particularly to coils of the high tension discharge type such as are used in ignition systelns for internal combustion engines and 5 in the operation of high frequency apparatus. It is well known in the art that in devices of this character, an interrupted or alternating current in a primary winding of comparatively few turns is stepped u or increased into a current of greatly ampliged voltage by means of a secondary windin of many turns. In the production of an e cient induction coil of this character, it is necessary to concentrate the wire of the seconda winding into a small compass so as to posltion practically all or at least the greater part of it inside the magnetic field of the primary winding and core. This construction necessarily places a limit upon the amount of insulation which can be used between the juxtaposed layers and between the adjacent turns in the same layer. Another condition which is to be encountered lies in the fact that if an insulation of high specific inductive l5 capacity be employed, the result is to amplify to an alarming factor the condenser effect between the successive layers of wire.

Ve have found that during the operation of the coil of this character there is superm imposed upon the ordinary and generally described secondary action, a static surging effeet wherein the amount of electricity involved is extremely small, but its electromotive force comparatively high. This effect reaches a maximum value or intensity in the region adjacent the extremities of the secondary coil structure. The effect of this high potential static charge appears to seek a path through the insulation after which the direct secondary discharge of greater quantity of lower potential is enabled to pass with its well known heating and disintegrating effect. In a coil wound in the normal manncr, the insulation adjacent the extremities of the secondary winding is none too high lwtween the adjacent layers; and break downs, burning or puncturing of the insulation usually occurs at these points.

This invention contemplates the utilization "0 of novel means for preventing a puncturing or breaking down of the insulation without enlarging the size of the coil structure and the invention comprehends the spacing of certain layers of wire, and maintaining the amount of insulation between the successive layers substantially uniform whereby the electric stresses are decreased and the condenser eiect between the several layers of wire is substantially reduced.

The invention has for a further object to provide a coil structure of this character wherein the elements of the coil per se are compactly assembled, forming a very elicient and inexpensive structure.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various detailsof construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as willv be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

Figure 1 is a vertical, longitudinal, sectional view through the coil of our invention;

Figure 2 is a detail sectional view taken substantially on a line 2 2 of Figure l;

Figure 3 is an enlarged fragmentary detail view of a portion of the coil structure;

Figure 4 is' an enlarged fragmentary dctail view of a portion of the coil structure showing the method of securing the leads to the windings.

We have shown our invention as embodied in an ignition coil suitable for use in the ignition system of an internal combustion engine, but it is to be understood that we do not wish to limit our invention to the particular embodiment illustrated, and that we contemplate the use of our invention wherever the same may be found to be applicable.

Referring more particularl to Figure 1, the coil structure comprises a aminated core 5 which is formed by assembling a plurality of iron or steel strips into a compact struc. ture which is subsequently inserted into tubes 6 and 8 of suitable insulating material, the

tubes 6 and 8 being surrounded by a second insulating tube 7. Surrounding the tube 7 is a secondary Winding 9, the construction of which will be hereinafter described in further detail.

Surrounding the secondary winding 9 is an insulating tube 11 upon which is wound a primary winding 12 superposed upon the secondary winding as shown in Figure 1. Surrounding the primary winding 12 is another insulating tube 14, the complete winding and core assembly being supported and housed within a cylindrical metallic casing 16. Interposed between the insulating tube 14 and the walls of the casing 16 is a plurality of metallic laminations 17 which are assembled as shown in detail in Figure 2. These laminations serve to form a path for the magnetic lines of force set up in the core andwindings thus making a very efficient structure. The several laminations 17 are of semi cylindrical form, the ends being slightly separated to form a gap which serves to decrease or reduce eddy currents.

One end of the core 5 is received into a bore in a supporting member 18 which may be of any suitable insulating material as, for example, porcelain which possesses hi h insulating qualities. One end of the casing 16 is adapted to be enclosed by means of a circular cover 20.

The other end of the casing 16 is enclosed by means of a metallic cap 22 which may be secured to the casing in any suitable manner as by soldering illustrated at 23, the crown of the cap being provided with an enlarged bore which receives a member 24 of porcelain or other insulating material, the inner end of said member having a frusto-conical bore which receives and supports the other end of the magnetic core structure 5. The outer extremity of the porcelain member 24 is provided with a bore 26 which contains a metallic thimble 27 forming the high tension terminal for the secondary winding, the thimble being connected to one end of the winding by means of a lead 29.

We have found that in order to prevent a derangement or loosening of the wire of the secon ary winding it is desirable to pass the lead 29 through a small aperture in the outer insulating tube 7 surrounding the core 5 as particularly shown in Figure 4, the lead passing between the adjacent'ends of the tubes 6 and 8. This arrangement serves as holding means for the end of the wire at the beginning of the winding operation and also tends to prevent an accidental breaking of the winding lead.

Positioned on either side of the orcelain member 24 are the primary termina 30 and 31 connected to the respective ends of the primary windings by means of leads 32 and 33. The terminals 30 and 31 are provided with threaded tenons 35 which are adapted to pass through enlarged openings in the cap 22, the tenons being s aced from the ed of the opening and wit the use of insulating washers 36 positioned on either side of the cap 22 a metallic connection hetween the terminals 30 and 31 and the cap 22 is avoided.

The coil structure is assembled before placing the cap 22 in position and any remaining cavities are filled with an insulating compound 37 which is impervious to moisture and which serves as an additional means to prevent derangement of the parts in the casing. The cap 22 may be soldered or otherwise iixedly secured to the casing 16.

The secondary winding structure will now be described in further detail. In the beginning of the operation of winding the secondary coil upon the tube 7, the first few layers of wire 40, preferably three or four, are so arranged that the individual turns or convolutions of wire are spaced one from the other whereby fewer number of turns are inclosed in the space occupied by the winding per se, the several layers of wire being separated by suitable insulating strips. The remaining layers of wire, with the exception of the outermost three or four layers of the secondary winding, are close wound, i. e. the individual convolutions are substantially in contact with each other. The outer layers of wire are s aced similarly to the inner layers of wire, t e several layers being separated by means of suitable strips of insulatmg material. It is to be understood that all the layers of wire are insulated one from the other and in the form shown, substantially the same amount of insulating material is used between each successive layer irres ective of whether the wire is close woun or space wound.

We have distributed the dielectric stresses produced by high inductive effects and os cillatinv currents close to the magnetic corel by spacing the turns or convolutions of the innermost and outermost layers of the secondary winding whereby a material saving is effected in the copper wire and insulating material used in the winding.

We have found it desirable in order to produce a coil of high eificiency, to decrease the number of turns in each successive layer in the primary winding, however, the several layers of the primar winding may be wound with an equal num r of turns which does not materially interfere with the successful operation of the coil.

It is apparent that, within the scope of the invention modifications and different arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What we claim is:

1. In a coil structure of the character disclosed comprising a core structure formed of a ,plurality-of flat metallic strips; insulating means surrounding said core; primary and secondary windings superpose upon said core structure; a metallic casing surrounding said core and windings; a plurality of semicylindrical metallic laminations interposed between said casing and said windings; a metallic cap for said casing; said metallic cap having an insulating member centrally disposed thereof; a metallic element carried by said insulating member and forming a terlminal for one of said coils; and a pair of coil terminals insulatingly supported upon said metallic cap.

2. In an ignition coil of the character disclosed comprising a core structure insulating means surrounding said core, yprimary and secondary windings superposed upon said core structure, said secondary winding comprising a plurality of layers of turns of wire; uniforml insulation between said layers; the turns of wire being closely wound in the central layers of said winding and, spaced apart at the beginning and end layers thereof as means for preventing a charge of high potential static from causing breakdown in said insulation; a casing surrounding said core hnd windings; a pluralit of lamlnations between said windings an said casing; a cap for said casing, said cap supporting the terminals for the ignition coil.

3. In a coil structure of the character disclosed comprising a laminated core structure; lnsulating means extending longitudinally of and surrounding said core; an insulating member having a recess into which one end of said core extends; primary and secondary windings superposed upon said core structure, said secondary being inside said primar and said core extending beyond the ends o said windings; said secondary winding comprising a plurality of layers of turns of wire; insulation between said layers; means associated with an end layer of said secondary winding `for preventing a charge of high potential static from causing breakdown in said insulation; a casing surrounding said core and windings; a curved structure between said windings and said casing arranged to prevent eddy current formations; a cap for said casing; an insulating member for the other end of said core having a recess into which said core extends; a mctallic element carried by said insulating member constituting a terminal for one of said windings; and a pair of coil terminals insulatingly supported upon said cap and insulatinU compound filling the remaining voids at either end of said coil.

4. In a coil structure of the character disclosed comprising a core structure; insulating means surrounding said core, primary and secondary windings superposed upon said core structure, said secondary winding comprising a plurality of layers of turns of wire;

insulation between said layers extendingbeyond said windings; the turns of wire being closely wound in the central layers of said winding and spaced apart at the beginning and end layers thereof; means associated w1th an end layer of said secondary winding for'preventing a charge of high potential static from causing breakdown in said insulation; a casing surrounding said core and windings; a plurality of laminations between said windings and said casing; a cap for said casing; said cap having an insulating member for said core and having a portion thereof extending into said layer insulation; a metallic element4 carried by said insulating member constituting y'a terminal for one of said windings; and a pair of coil terminals insulatingly supported upon said cap.

5. In a. coil structure of the character disclosed comprising a core structure; insulating means surrounding said core; a secondary winding superposed upon said core structure; a primary winding superposed on said secondary winding; said secondary winding comprising a plurality of layers of turns of wire; insulation between said layers; means associated with an end layer of said secondary winding for preventing a charge of high potential static from causing breakdown in said insulation; a casing surrounding said core and windings; a plurality of semi-circular lcurved separate laminations shaped to fit around said primary winding and located between said winding and said casing; means to prevent eddy current formations in said laminations; a cap for said casing; said cap having an insulating member for said core; a metallic element carried by said insulating member constituting a terminal for one of said windings; and a' pair of coil terminals insulatingly supported upon said cap.

6. In a coil structure of the character disclosed comprising a core structure; primary and secondary windings superposed upon said core structure said windings being shorter than said core, said secondary winding comprising a plurality of layers of turns of wire; insulation between said layers; means associated with an end layer of said secondary winding for preventing a charge of high potential static from causing breakdown in said insulation; insulation tubing surrounding the core structure which extends beyond said winding, said tubing also extending into the said winding structure; a casing surrounding said core and windings; a plurality of laminations between said windings and said casing; a cap for said casing, said cap having an insulating member for said core a metallic element carried by said insulating member constituting a terminal for one of said windings; and a pair of coil terminals insulatingly supported upon said cap.

In an ignition coil of the character disclosed comprising a core structure; insulatizo ing means surrounding said core; primary and `secons'iai! windings superposed on said ocre structure insulated therefrom, said secondary winding comprising a plurality of layers of turns of wire; sheet insulation between said iayers; means for reventmg 1a charge or" high potential static om causing break down in said insulation; a casing surrounding said core and windings; metallic sheet material between said windings and said casing forming an outer magnetic field; acap for said casing, said cap supporting the terminals for said coil; and means for securin the cap to said casino'.

8. n a coil structure of the character disclosed comprising a core structure; insulating means extending longitudinally of and surrounding said core; an insulating member having a recess into which one end of said core extends; primary and secondary windings superposed upon said core structure, said secondary winding being inside said primary winding and comprising a plurality of layers of turns of wire; insulation between said layers; means associated with an end layer of said secondary winding for preventing a charge of high potential static from causing break down in said insulation; a casing surrounding said core and windings; a curved structure between said windings and said casing arranged to prevent eddy current formations; an insulating member adjacent to the other end of said core having a recess into which said core extends; a metallic element carried by said insulating member constituting a terminal for one of said windings; a plurality of coil terminals adjacent to said metallic element and insulated therefrom; and insulatin compound filling the voids -between the e ements of the coil assembly.

9. In a coil structure of the character disclosed comprising a magnetizable core structure; primary and secondary windings superposed upon said core structure insulated therefrom, said secondary winding comrising a plurality of layers of turns of wire; insulation between said layers extending beyond said windings; means associated with an end layer of said secondary winding for preventing a charge of high potential static for causing break down in said insulation; a casing surroundin said Acore and windings; sheet material etween said windin and said casing; a cap for said casing said cap having an insulating member provided with a terminal for said coil and extending within the casing adjacent said layers of insulation; and a plurality of coil terminals supported upon said cap.

10. In a coil structure of the character disclosed comprising a core structure; insulating means surrounding said core; a secondary winding superposed upon said core structure; a primary winding supersed u on said secondary winding, and insulate therefrom, Said secondary winding comprising a plurality of layers of turns of wire; substantially uniform insulation between said layers; means associated with an end layer of said secondary winding for preventing a charge of high potential static from causing brea down 1n said insulation; a tubular casing surrounding said core and windings; metallic sheet material shaped to fit around said primary winding and located between said winding and said casing, providing an outer magnetic field; means to prevent eddy current formations in said sheet material; a cap for the one end of said casing, said cap having an insulating member extending within the casing and carrying means on the outside thereof constitutin a terminal for one of said windings; a pair of coil terminals supported upon said cap; and means to secure said cap to said casing.

l1. In a coil structure of the character disclosed comprising a core structure; primary and secondary windings superposed said core structure; said windings being shorter than said core, said windings comrising a plurality of layers of turns of wire; insulation between said layers; means associated with an end layer of said secondary t winding for preventing a charge of high potential static from causing break down in said insulation; tubing surrounding the Core structure insulatingly supporting said windings from said core; a tubular casing surrounding said core and windings; metallic sheet material between said windings and said casing; a cap for said casing, said cap supporting the terminals for the coil; and means to secure said ca to said casing.

In testimony whereo we aix our signatures.

WILLIAM G. SCHNEIDER. HARRISON H. EATON.

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