US3368177A - Wound inductor coil form - Google Patents

Description

Feb. 6, 1968 R. H. HILGERS wounn INDUGTOR coIL. FORM Filed June 7, 1966 INVENTOR: RAYYMOND H. HILGERS ATT'YS f) at United States Patent D 3,368,177 WOUND INDUCTOR COIL FORM Raymond H. Hilgers, Roselle, 11]., assign-or to Resinite Corporation, Wheeling, 111., a corporation of Illinois Filed June 7, 1966, Ser. No. 555,776 6 Claims. (Cl. 336-203) ABSTRACT OF THE DISCLQSURE A coil form for supporting an electrical winding. The coil form comprises an elongated tubular body provided with a plurality of circumferentially spaced longitudinally extending recesses in the outer wall thereof. The recesses define thin web portions which connect relatively thick portions adjacent each recess, and each web portion is provided with an interiorly projecting web for engagement with a core. The outer surface of the web portions are spaced from the outer surfaces of the thick portions to permit outward flexure of the web portions.

This invent-ion relates to a coil form, and, more particularly, to a tubular element adapted to be incorporated into electronic apparatus as an inductor.

Exemplary of the use of the invention is in connection with IF coils used in radio and television receivers. These require adjustment by means of positioning a core within the tubular coil form. Such cores are usually constructed of powdered iron and are quite delicate, i.e., frangible. Over the years, various expedients have been employed for properly sup-porting the cores within the tubular coil forms. Most commonly, the coil forms are equipped with female threads to receive the cores at various positions so as to change the inductive value of the coil. It will be appreciated that the inductive value is not only governed by the position of the core, but also by the configuration, i.e., total geometry, of the windings. This places a distinct limitation on the character of coil forms heretofore employed. I find that this limitation is overcome and avoided through a novel construction making use of circumferentially spaced resilient web portions, and the provision of such a coil form constitutes an important objective of this invention.

Other objects and advantages of the invention may be seen in the details of construction and operation set down in this specification.

The invention is described in conjunction with an illustrative embodiment in the accompanying drawing, in which:

FIG. 1 is a perspective view of a coil form constructed according to this invention;

FIGv 2 is an enlarged transverse sectional view taken along the line 22 of FIG. 1; and

FIG. 3 is a view similar to FIG. 2, but showing a core installed in place in the form and wherein the form is equipped with the usual windings.

In the illustration given and with particular reference to FIG. 1, the numeral designates generally the inventive coil form which is seen to include a unitary body equipped with a perimetric flange 11 adjacent one end and which constitutes a stop for mounting the form on a chassis or other electronic gear-supporting frame. Advantageously, the body 10 is constructed of substantially rigid plastic material having resilient properties such as unplasticized polyethylene and which is an electrical insulator.

Extending generally from the vicinity of the perimetric flange 11 are a plurality of longitudinally-elongated recesses 12 which are seen to extend from the outer surface of the coil form body 10 into the body proper and which 3,358,177 Patented Feb. 6, 1968 define web or bight portions 13. The web portions 12 are flanked by shoulders 14 which extend generally at about 45 to a median radius 15, so as to define the angle as indicated on the drawing. -In addition, each web is equipped with longitudinally-extending rib portions projecting inwardly of the tubular coil form as at 16.

In operation, when the core 17 (see FIG. 3) is installed, there is a limited flexure of the relatively thin and, therefore, slightly resilient web portions 13, as indicated in FIG. 3, so as to move the same into the recesses 12, but without disturbing the overall geometry of the coil form which is important in governing the inductance of the various windings 18. This is particularly advantageous in that the threads of the powdered iron core 17 do not have to cut into the rib 16. It will be appreciated that such cores are quite frangible and a slight excess of torque can cause rupture. The partial destruction of a core can result in a change in the inductance of the coil achieved by over-winding the form 10 as at 18.

The molded coil form of the invention is particularly advantageous in reducing the amount of torque needed to insert the core 18. Here, it will be appreciated that the core is inserted into the form 10 from the end 19 (see FIG. 1) while the form 10 is supported at the end designated 20. For this purpose, the unitary member 10 is equipped with integral longitudinal-extending flanges as at 21 separated by slots 22 which accommodate the mounting of the coil form 10 by permitting the same to be snapped onto a chassis (not shown).

A specific example of the invention for use with a core having a nominal diameter (O.D. of the thread) of 0.248" and an ID. of the undistorted form (see FIG. 2) of 0.254". The diameter between opposed ribs 16 is 0.232", resulting in inwardly-extending ribs of the order of 0.008"-0.0l2". The thickness of the bight or web portion 13- is of the order of 0008" resulting in an outside diameter between exteriors of the bight portions of 0.270. Finally, the dimension A in the illustration given wherein there are four recesses at 12, is 0.160".

While in the foregoing specification, a detailed description of an embodiment of the invention has been set down for the purpose of illustration, many variations in the details herein given may be made by those skilled in the art without departing from the scope of the invention.

I claim:

1. A coil form for supporting an electrical winding, com-prising a relatively elongated unitary tubular body constructed of non-electrically conductive material having resilient properties, a plurality of circumferent-ially spaced-apart, longitudinally-extending recesses in the outer wall of said form defining relatively thin and relatively flexible web portions interconnecting relatively thick and relatively rigid portions adjacent each recess, said web portions being substantially thinner than said thick portions, each web portion being equipped with an interiorly projecting, longitudinally-extending integral rib for engagement with a threaded core whereby the web portion is adapted to selectively flex to accommodate said core.

2. The structure of claim 1 wherein said recesses terminate short of the ends of said body.

3. The structure of claim 1 in which said recesses are defined and flanked by shoulders arranged at about 45 angles relative to a median radius extending through an associated rib.

4. An electrical inductance comprising a coil form having a relatively elongated unitary tubular body constructed of non-electrically conductive material having resilient properties, a plurality of circumferentially spacedapart, longitudinally extending recesses in the outer wall of said form defining relatively thin web portions interconnecting relatively thick portions adjacent each recess,

each web portion being equipped with an interiorly projecting, longitudinally extending integral web for engagement with a threaded core, a winding on said form supported by said thick portions and spaced from said web portions, whereby the web portion is adapted to selectively flex to accommodate a core.

5. The structure of claim 4 in which said recesses terminate short of the end of said body.

6. The structure of claim 4 in which said recesses are defined and flanked by shoulders arranged at about a 45 angle relative to a median radius extending through an associated web.

References Cited UNITED STATES PATENTS 2,328,335 2,631,192 3/1953 Wallin 336-136 X 3,129,348 7/1964 Simmons 242-418 FOREIGN PATENTS 866,952 4/ 1961 Great Britain,

10 LARAMIE E. ASK'IN, Primary Examiner.

E. GOLDBERG, Assistant Examiner.

8/1943 Fryer 2421l8.2

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