US3138771A - Meltable plastic spacer for securing coil to tubular support and housing, and methodof assembly - Google Patents

Description

3,138,771 TUBULAR OF ASSEMBLY 1958 June 1964 B. M. GOLDSMITH ETAL MELTABLE PLASTIC SPACER FOR SECURING COIL TO SUPPORT AND HOUSING, AND METHOD Original Filed Feb. 19,

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United States Patent 3,138,771 MELTABLE PLASTIC SPACER FOR SECURING COIL T0 TUBULAR SUPPORT AND HOUSING, AND METHOD OF ASSEMBLY V 7 Bernard M. Goldsmith, Little Silver, N.J., and Walter T.

Sutton, .Ir., Lexington, Ky., assignors, by mesne assignments,to Nytronics, Inc, Phillipshurg, N.J., a corporation of New Jersey Continuation of application Ser. No. 716,106, Feb. 19, 1958. This application Dec. 12, 1961, Ser. No. 162,623 3 Claims. (Cl. 336*92) Our invention relates to an improved electrical coil and transformer construction rendering the same particularly useful in the automatic assembly of such circuit components into circuits, as into printed circuits. This application discloses improvements over and modifications of the various forms disclosed in copending Goldsmith application Ser. No; 626,175, filed December' t, 1956, now Patent No. 2,836,805. The present application is a continuation' of my copending application Ser. No. 716,106, filed February 19, 1958.

It is an object of the invention to provide an improved construction of the character indicated.

It is another object to provide an improved electricalcoil circuit element which can be fabricated at substantially reduced cost.

It is a specific object to achieve the above objects with a construction in which the ends of the wire of the coil or coils are themselves the mounting prongs, of strength adequate to provide the substantial mounting support for the circuit element.

It is in general an object to meet the above objects with an extremely rugged and simple device which can achieve or exceed the electrical performance of previous structures, and which may be so rugged and permanent as to constitute a trouble-free component for the life of the circuit in which it is embodied.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification, in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention;

FIG. 1 is a longitudinal sectional view (taken along the line 1-1 of FIG. 3) of a coil construction embodying features of our invention and just prior to a final assembly step;

FIG. 2 is a view similar to FIG. 1, but illustrating completion of the final step;

FIG. 3 is a bottom-end view of the structure of FIGS. 1 and 2;

FIG. 4 is a view similar to FIG. 1 to illustrate a modification;

FIG. 5 is a view in perspective to illustrate an element of FIG. 4; and

FIG. 6 is a fragmentary longitudinal sectional view to illustrate a further modification.

Briefly stated, our invention contemplates application to the construction of coils, transformers, chokes and the like for use in electronic circuit assemblies, as for example, in the video amplifier of a television set. The construction features integral formation of the turns of the electrical coil with the mounting leads or prongs and, for this purpose, employs relatively heavy and stiff wire for the turns of the coil or coils. The assembly is made rugged and adaptable to receive an adjustably positioned magnetic core by securing the same with a plastic bonding agent, such as an epoxy resin.

The particular feature of the present invention is the employment of an initially solid fusible member assembled with the coil and its housing and in adjacency with 3,138,771 Patented June 23, 1964 the coil, the said member having a melting point substantially lower than the melting point of the housing, so that upon the passage of a heating current of sufiicient intensity through the turns of the winding after initial as sembly, the fusible member may be melted and allowed to flow into bonding relationship with the turns of the winding and the housing, thereby completing the permanent nature of the assembly.

In one form to be described, the fusible member serves as an axial spacing member for precisely determining the extent to which a given winding will be inserted upon initial assembly into its housing. In the other form to be described, the fusible member is a ribbon of suitable material interleaved with the turns of the winding. In both cases, the fusible member is in direct contact with the winding so that permanent bonding maybe achieved merely by heating the winding after assembly.

Referring to FIGS. 1, 2 and 3 of the drawings, our invention is shown in application to a coil assembly in which the coil 10 is developed or received upon, and concentrically supported by, a tubular coil-form portion or stem 11 of a plastic body member 12; it will be appreciated that concentric support, as used here, contemplates substantial coincidence of the axes of the coil and ,of the coil-form. The body member 12 may be generally cupshaped and, in addition to the tubular member 11, may include an outer tubular member 13, joined at the upper end, as'at 14, to the inner tubular member 11, so as to define therewith an annular space 15 open at the lower end to receive insertion of the'winding 10.

The winding 10 is developed from relatively heavy and stiff insulating wire and is shown as a single layer of turns, the ends of which are so formed and trimmed as to project axially beyond the axial confines of the coil and so as to project axially beyond the open end of the housing 12 when assembled thereto. Heavy plastic-coated copper magnet wire or Copperweld (coppersheathed steel wire) is well adapted to form the winding means 10.

The wire from which the winding 10 is formed is preferably so rugged that the projecting ends 16-17 of the coil 10 may serve as the mounting pins for the finished structure, so that no soldering or other connection to separate mounting pins is necessary to integrate the circuit component into its ultimate chassis. For convenience in mounting, the leads 1617 may be nail-pointed by employing conventional machinery, but we indicate our preference that the projecting ends 16-17 shall be merely dipped in a pool of solderand slowly raised so as to develop pointed solder ends 16'17 in the manner of a .stalactite, the solder being further desirable for ultimate simpler permanent assembly into a printed circuit. The leads 161 7 may project for different axial lengths, thereby p'rovidingunambiguous terminal identification.

Various means may be employed to close the open end' .of the container once the winding 10 has been assembled therein, and in the form shown we employ the means described in greater detail in Goldsmith application Serial No. 715,377, filed February 14, 1958. The closure means may thus comprise a separate cover 18 of plastic material which may be formed of the same kind of material as thehousing 12; the cover 18 is with a plurality of angularly spaced openings 21-222324, and two of these openings 22-24 are employed to locate the axially projecting integral ends 16-17 of the winding 10. The cover 18 is preferably so designed as to fit with a forcefit within the outwardly flared end of the slightly tapered outer tubular member 13 of the body 12. The closure member 18 also has a central opening through which the stem 11 of the housing 12 projects, and the outwardly projecting ends may be formed over, as by spinning, to define a b ead 19 for retaining the parts in permanently assembled relation.

the inner end of the outer winding 26.

In accordance with the invention, precise preliminary assembly is achieved by first inserting a spacer abutment member or pellet 20 of annular shape over the central tubular housing part or stem 11 and by then applying the winding in direct axial abutment therewith, the spacer member 20 being so devised'as to define the exact desired abutment plane for the inner end of the winding 10. Upon thereafter securing the cover 18 by means of the bead 19, precise and accurate location of the winding 10 on the stem 11 is achieved, and for many purposes, the assembly may be considered complete.

In accordance with a preferred employment of the invention, the spacer abutment member or ring 20 is made of a plastic material having a substantially lower melting point than that of the housing 12. The melting point should be such that normal operating temperatures of the coil 16 will not be anywhere near adequate to soften the material of member 20, but so that, upon heating for assembly purposes to a temperature elevated with respect to normal operating temperature, the member 20 may be caused to melt. Thus, once the parts have been assembled preliminarily into the relationship shown in FIG. 1, a current of sufficient intensity is passed through the winding by establishing connections at 16-17, and the material of spacer 20 is caused to flow. If the assembly is oriented with the closed end or cover 18 facing downwardly, then the flow of plastic material will fill the interstices between winding turns and the coil form or stem 11, and will assume a final relationship within the housing as suggested at 25 in FIG. 2, thus permanently bonding the winding turns to the coil stem and to the cover 18. It is not necessary to achieve a bonding to the inner wall of the outer tubular portion 13 of the housing, but if this occurs, no harm is done, the assembly being thereby made that much more rugged.

In the arrangement of FIG. 4, we illustrate employment of the principles discussed in connection with FIGS. 1, 2 and 3 for the accommodation of parts of a transformer, the principal dilference between FIGS. 1 and 4 being the showing of a second winding 26 which may be of generally the same nature as the winding 10, except for being wound on a slightly larger diameter so as to derive concentric support from the periphery of the winding 10. As with the case of the winding 10, the ends of the winding 26 may be bent axially out the open end of the container for location in the remaining openings 21-23 of the cover 18 and for projection therebeyond. The said wire ends for the second coil 26 are suggested at 2728 in FIGS. 3 and 4.

In accordance with a further feature of the invention, the automatic assembly of a transformer such as that shown in FIG. 4 is facilitated and made more precise by so contouring the end of the spacer pellet 20' that unique, positive, direct locating abutment is achieved for both windings 10-26 of the assembly. In the case of FIG. 4, it is assumed that the outer winding 26 has fewer turns than the inner winding 10, and that the axially inner end of the winding 10 shall extend further inwardly into the housing 12 than does the corresponding axially inner end of the outer winding 26. In the form shown, the spacer pellet 20' includes an additional projecting element 29 extending axially beyond the main body of the spacer pellet 20' so as to determine a positive limit for Thus, upon preliminary assembly, the parts may be axially abutted in the relation shown in FIG. 4, and the housing may be secured by beading the stem at 19 into retaining relation with the cover 18. Upon subsequently heating one or both of the windings 111-26, the material of the fusible spacer pellet 2th will commence to flow, so that. on cooling, a bonded relationship is established for the turns of the two windings to each other and to the stem 11, as well as to thecover 18, and perhaps also to certain parts of the skirt or outer tubular part 13 of the housing 12.

In the arrangement of FIG. 6, the parts may be preliminarily assembled in the manner discussed in said Goldsmith application Ser. No. 715,377, or they may be assembled against a non-fusible spacer pellet or shoulder (not shown, but similar to that shown at 20 in FIG. 1). The principal difference between the embodiment of FIG. 6 and those of FIGS. 1 and 4 is that the fusible material employed for plastic bonding is a ribbon 30 helically developed in interleaved relation with the turns of the winding 10 or 26, as the case may be. This will mean a slight spacing between successive turns of the winding 10 or 26, but once the parts have been assembled and a heating current passed through the turns of the winding, the ribbon 30 will melt; thus, on cooling, bonding to the coil form or stem 11 will be secure and permanent, so that electrical characteristics will be permanently retained.

As indicated, it makes no difference whether the plastic ribbon is interleaved with the primary or secondary turns in the case of a transformer, but in FIG. 6, I suggest the employment of the bonding ribbon 30 merely for the inner winding, namely the winding 10; in FIG. 6, turns for the outer winding 26 are suggested in phantom outline. In either case, heating current passed through the winding carrying the bonding ribbon 30 will be sufficient to achieve bonding of the turns of both windings to each other and to the stem 11.

It will be seen that we have described a relatively simple yet efiicient coil construction lending itself to automated fabrication and to automated later assembly into a circuit sub-assembly, as into a printed circuit, the key means 31 being such as to facilitate unambiguous location in such assembly. In all cases, the lead wires are adequate to support the entire structure, even for automatic circuit-assembly handling, and yet they are integral with the turns of the coil or coils.

While we have described the invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of the invention as described in the claims which follow.

We claim:

1. In combination, a plastic cup-shaped housing comprising inner and outer tubular portions joined at one end to define an elongated annular space open to the other end, an electrical winding comprising a plurality of turns of relatively heavy and still wire of axial extent less than the axial extent of said annular space and supported by and deriving concentric support directly from one of said tubular portions, a ring-shaped spacer pellet of plastic material substantially coaxial with the housing axis and having a melting point substantially less than that of said housing and received within said space in axially abutting relation with the closed end of said housing and in axially abutting relation with the adjacent end of said winding, whereby a positive initial axial location may be developed for axially assembling said winding within said annular space, and whereby, upon such initial assembly, and upon the passage of a heating current through said Winding, bonding material may be available from said spacer pellet to permanently bond the turns of said winding to said housing.

2. In combination, a plastic cup-shaped housing comprising inner and outer tubular portions joined at one end to define an elongated annular space open to the other end, an electrical winding comprising a plurality of turns of relatively heavy and still? wire of axial extent less than the axial extent of said annular space and supported by and deriving concentric support directly from one of said tubular portions, a ring-shaped spacer pellet of plastic material substantially coaxial with the housing axis and having a melting point substantially less than that of said housing and received within said space in axially abutting relation with the closed end of said housing and in axially abutting relation with the adjacent end of said winding, a second electrical Winding comprising a plurality of turns of relatively heavy and stiff wire supported by and deriving concentric support directly from said first winding, said spacer pellet being formed at the radius of turns of said second winding with an axially projecting portion extending beyond the location of pellet abutment with said first winding and in axially locating relation with the adjacent end of said second winding; whereby desired initial axially located relations between both windings and the housing may be developed, and whereby upon passage of the heating current through one of said windings, said windings may be bonded to each other and to said housing in the desired relationship.

3. The method of permanently assembling an electrical coil of relatively heavy and stiff wire to a tubular plastic coil form having an integral annular radially outwardly extending flange part at one end, which comprises the steps of preforming said wire into an axially extending plurality of turns of substantially the outer diameter of said coil form, the ends of said wire being formed straight and projecting axially beyond the same single end of said turns and in angularly spaced relation, assembling a 20 spacer washer of thermoplastic bonding material over said coil form and in axially abutting relation with said flange, assembling said coil to said coil form in axially abutting relation with said washer, whereby the axial location of said coil with respect to said flange is uniquely and accurately defined, passing a sufiicient electric current through said coil to locally melt at least a part of said thermoplastic bonding material, and removing said current to allow cooling to thereby bond a part of said coil to a part of said coil form.

References Cited in the file of this patent UNITED STATES PATENTS 812,657 Kitsee Feb. 13, 1906 2,455,136 Obert May 30, 1948 2,695,856 Firth Nov. 30, 1954 2,836,805 Goldsmith May 27, 1958 2,941,172 Sutton June 14, 1960 3,014,190 Sutton Dec. 19, 1961 3,024,433 Goldsmith Mar. 6, 1962

Claims (1)

1. 2. IN COMBINATION, A PLASTIC CUP-SHAPED HOUSING COMPRISING INNER AND OUTER TUBULAR PORTIONS JOINED AT ONE END TO DEFINE AN ELONGATED ANNULAR SPACE OPEN TO THE OTHER END, AN ELECTRICAL WINDING COMPRISING A PLURALITY OF TURNS OF RELATIVELY HEAVY AND STIFF WIRE OF AXIAL EXTENT LESS THAN THE AXIAL EXTENT OF SAID ANNULAR SPACE AND SUPPORTED BY AND DERIVING CONCENTRIC SUPPORT DIRECTLY FROM ONE OF SAID TUBULAR PORTIONS, A RING-SHAPED SPACER PELLET OF PLASTIC MATERIAL SUBSTANTIALLY COAXIAL WITH THE HOUSING AXIS AND HAVING A MELTING POINT SUBSTANTIALLY LESS THAN THAT OF SAID HOUSING AND RECEIVED WITHIN SAID SPACE IN AXIALLY ABUTTING RELATION WITH THE CLOSED END OF SAID HOUSING AND IN AXIALLY ABUTTING RELATION WITH THE ADJACENT END OF SAID WINDING, A SECOND ELECTRICAL WINDING COMPRISING A PLURALITY OF TURNS OF RELATIVELY HEAVY AND STIFF WIRE SUPPORTED BY AND DERIVING CONCENTRIC SUPPORT DIRECTLY FROM SAID FIRST WINDING, SAID SPACER PELLET BEING FORMED AT THE RADIUS OF TURNS OF SAID SECOND WINDING WITH AN AXIALLY PROJECTING PORTION

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