US3434088A - Coil structure - Google Patents

Description

March 18, 1969 R. s. z|E| Es 3,434,088

COIL STRUCTURE Filed Oct. 17, 1967 F/G.-/ 4g 7 big/Z /0 I mus/v70? E. S. Z/ELES 4 7' TOR/VE V United States Patent 3,434,088 COIL STRUCTURE Robert S. Zieles, Indianapolis, Ind., asslgnor to Bell Telephone Laboratories, Incorporated, Murray Hill, Berkeley Heights, N.J., a corporation of New York Filed Oct. 17, 1967, Ser. No. 675,909 US. Cl. 336-192 8 Claims Int. Cl. H01f /10, 27/28 ABSTRACT OF THE DISCLOSURE A coil structure comprises a coil wrapped around a spool that is accommodated by a cup-shaped frame. A flange on the spool has a pair of bifurcated extensions about which the initial and final turns of the coil are respectively wound, and one or more of these turns are ultrasonically welded to rivets mounted in the base of the frame.

Field of invention This invention relates to the field of electrical components and within that field to electrical coils. Furthermore, this invention while not limited thereto is particularly adapted for miniaturization.

Background of the invention With the development of solid state devices, miniaturization of electrical components has taken on a new impetus and even though integrated circuits are now coming into commercial use, there still exists a need for miniature coils. Such coils are employed in miniature relays, inductors, transducers, and so on.

One of the major problems in the manufacture of miniature coils has been providing terminations for the coils. The coils are wound with fine wire that is easily broken and therefore this Wire cannot itself be used for connecting the coil into the circuit in which it is to be employed. Rather the fine wire of the coil must be electrically connected to heavier lead wires or terminals which are then used to connect the coil to the circuit.

The problem consists of providing a coil structure that permits the electrical connection between the wire of the coil and the lead wires or terminals to be made using production line techniques.

Summary of the invention A coil structure is herein disclosed that provides a solution to the above problem. The coil structure comprises a spool having a flange at one end thereof that includes a pair of bifurcated extensions, the extensions having a particular spatial relationship with respect to one another. The initial turns of the coil are Wrapped around one of the extensions and the final turns of the coil are wrapped around the other of the extensions, one or more of the turns in each case spanning the space between the bifurcations.

T-he spool is positioned on a base that has a pair of holes therein, the holes having the same spatial relationship with respect to one another that the bifurcated extensions have to one another, and a rivet that has a solid top and hollow bottom is mounted in each hole. The spool is positioned on the base so that the wire-wrapped bifurcated extensions are in juxtaposition with the tops of the rivets, and one or more of the turns of wire wrapped around the extensions are ultrasonically welded to the rivets. The termination of the coil structure is completed by the soldering of a lead wire to the hollow underside of each rivet.

3,434,088 Patented Mar. 18, 1969 "ice Description of the drawing Detailed description Referring to FIGS. 1 and 2 of the drawings, the coil structure of this invention includes aspool 10 comprising atubular hub 12 and asingle flange 14 at one end of the hub. Theflange 14 includes a pair of bifurcatedextensions 15 that have a particular spatial relationship to one another, the bifurcated extensions in the embodiment shown in the drawing being diametrically opposed to one another.

Acoil 16 is wrapped around thespool 10, the initial turns of the coil being wound around one of the bifurcatedextensions 15, the body of the coil being wound around thehub 12, and the final turns of the coil being wound around the other bifurcated extension. One or more of the turns wound on each bifurcatedextension 15 span the space between the bifurcations, and to keep the turns from spilling off they are advantageously coated with a thin layer of cement. As an alternative, wire coated with an adhesive insulation is employed, and either immediately before or after wire is wound on the spool, the adhesive layer is activated by solvent or heat to cause bonding between adjacent turns.

Thespool 10 with thecoil 16 thereon is accommodated by a dielectric cup-shaped frame 18 comprising aplanar base 20 and acylindrical rim 22. Thebase 20 has acentral hole 24 and a pair oflateral holes 25, acircular recess 26 encompassing each of the lateral holes. Thelateral holes 25 have the same spatial relationship with respect to one another that the bifurcatedextensions 15 of thespool 10 have to one another.

Eachlateral hole 25 and therecess 26 therearound accommodates an electrically conductingrivet 28. Eachrivet 28 has asolid head 30 and atubular shank 32, and each rivet is positioned in ahole 25 with the head in therecess 26 and the shank extending through the hole. Therivets 28 are secured in place by swaging thetubular shanks 32 onto the underside of thebase 20, and when so secured the tops of theheads 30 are substantially flush with the nonrecessed upper surface of the base.

Thespool 10 with thecoil 16 thereon is positioned with theflange 14 on the upper surface of thebase 20, with thehub 12 overlying thecentral aperture 24 in the base and with one or more of the turns wrapped around the bifurcatedextensions 15 overlying theheads 30 of therivets 28. Thespool 10 and thebase 20 advantageously include means, such as locating studs on one and receiving holes in .the other, for providing this orientation automatically.

One or more of the turns of wire wrapped around each bifurcatedextension 15 are ultrasonically welded to thehead 30 of therivet 28 therebeneath. The tip of the ultrasonic welding toolis applied to one or more of the turns of wire at the point that they extend between the bifurcations, the tip pressing the wire against thehead 30 of therivet 28. Ultrasonic energy is then applied to the welding tip and the activated tip strips the insulation from the wire, removes the oxide'from thehead 30, and bonds the wire to the head all in one operation.

Termination of the coil structure is completed with the soldering of alead wire 34 to the underside of eachrivet 28. Since theshank 32 of eachrivet 28 is tubular, the underside of the rivet has a cavity therein. This cavity accommodates the end of alead wire 34 and thereby facilitates the soldering of the lead wire to therivet 28. Soldering of thelead wires 34 to therivets 28 is possible because the ultrasonic welding of the coil wires to the rivets provides a metallurgical bond that is not disturbed by the heat generated in the soldering operation.

The cup-shaped frame 18 serves as an enclosure for thecoil 16 and if desired the coil can be potted therein. In addition, since thehub 12 of the spool is in registration with thecentral opening 24 in theframe 18, a core or pole piece can be readily inserted into the hub. Thus the coil structure is readily adaptable to a number of different uses.

What is claimed is:

1. A coil structure comprising:

a base having a planar surface in which a pair of spaced holes are formed, the holes having a particular spatial relationship with respect to one another;

an individual electrically conducting rivet mounted in each hole in the base;

a spool having a flange at one end thereof that includes a pair of bifurcated extensions, the bifurcated extensions having the same spatial relationship with respect to one another that the holes in the base have to one another; and

a wire coil wound around the spool, the initial turns of the coil being wound around one of the bifurcated extensions and the final turns of the coil being wound around the other bifurcated extension, the turns being wound so that at least one spans the space between the bifurcations;

the wound spool being positioned on the base with the bifurcated extensions overlying the rivets and one or more of the turns of wire extending between the bifurcations of each extension being electrically connected to the top of the rivet therebeneath.

2. A coil structure as in claim 1 wherein the base is formed from a dielectric material.

3. A coil structure as in claim 1 further including a lead wire electrically connected to the underside of each rivet.

4. A coil structure as in claim 1 wherein the base includes a recess that encompasses each hole, the recess about each hole being of a size to accommodate the head of the rivet positioned in the hole and being of a depth so that the top of the rivet is substantially flush with the nonrecessed surface of the base.

5. A coil structure as in claim -1 wherein one or more of the turns of wire extending between the bifurcations of each extension are ultrasonically welded to the rivets therebeneath.

6. A coil structure as in claim 1 wherein the base is part of a cup-shaped frame that accommodates the wound spool.

7. A coil structure as in claim 2 wherein the lower ends of the rivets are tubular and thereby permit soldering of the lead wires therein.

8. A coil structure comprising:

a dielectric base having a planar surface in which a pair of spaced holes are formed, the holes having a particular spatial relationship with respect to one another, the base further having a recess that encompasses each hole;

an individual electrically conducted rivet mounted in each hole in the base, the head of each rivet being accommodated by the recess encompassing the hole, and the top of the rivet being substantially flush with the nonrecessed surface of the base;

a spool having a flange at one end thereof that includes a pair of bifurcated extensions, the bifurcated extensions having the same spatial relationship with respect to one another that the holes in the base have to one another; and

a wire coil wound around the spool, the initial turns of the coil being wound about one of the bifurcated extensions and the final turns of the coil being wound about the other bifurcated extension, one or more of the turns being wound so that they span the space between the bifurcations.

the wound spool being positioned on the base with the bifurcated extensions overlying the rivets and one or more of the turnsof wire between the bifurcations of each extension being ultrasonically welded to the top of the rivet therebeneath.

References Cited UNITED STATES PATENTS 3,007,125 10/1961 Furbee 336-192 X 3,271,760 9/1966 Sloan.

LEWIS H. MYERS, Primary Examiner.

E. GOLDBERG, Assistant Examiner.

US. Cl. X.R. 3 36208

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