US 3197167 A
Description (OCR text may contain errors)
, 1955 A. c. STURGIS MOUNTING CLIP FOR POT CORE July 27 Filed April 1, 1965 FIG? INVENTOR ANDREW C. STURGIS,
United States Patent 3,l7,167 MUUNTHNG CLllP 1 8T Cti llll Andrew C. S turgis, llynchburg, Vac, assignor to General Electric Company, a corporation of New York Filed Apr. 1, 1963, Ser. No. 269,584 3 Gaines. (til. 243-314) This invention relates to fastening devices for securing a plurality of electrical components in a fixed spatial relationship. More particularly, the invention relates to a mounting clip for firmly securing a plurality of ferrite core members.
High fre uency inductive devices such as pulse transformers, filter inductances, etc, frequently utilize magetic core members formed of ferrite materials. Ferrites, which are oxides of various ferrous elements, are characterized by high permeability and high resistivity, thereby permitting efficient operation while yet minimizing eddy current losses. Ferrite magnetic cores are often fabricated as semi-cylindrical cup-like elements which include a center leg or projection. Two of these cup-core members are assembled to form the magnetic core, with the center legs forming an air gap which controls the reluctance of the magnetic circuit. One or more coils surrounds these center legs or projections and are customarily mounted on a nonmagnetic bobbin fitting inside of the annular space formed by the cup-core halves and their center projections or legs. It is immediately apparent that the inductance of the device is controlled to a substantial degree by the reluctance of the magnetic circuit which, in turn, is determined by the dimensions of the air gap formed by the center legs of the cup cores. Hence, it is quite important that the individual cup-core halves forming the core of the inductor be ri idly and fixedly mounted in order to maintain the proper air gap, and to prevent relative rotational movement of the cupcore halves.
it is, therefore, a primary object of this invention to provide a mounting means for a ferrite cup core inductive device in which the cup core members are firmly and rigidly maintained in a desired abutting relationship.
In the past, it has been customary to assemble the cup cores in the desired fixed spatial relationship while simultaneously mounting them on a chassis or printed wiring board by means of a clip or other fastening means. The fastening means exerts force on the cup cores during the assembling process and brings them into an abutting relationship. This arrangement for assembling the cup cores of the inductive devices leaves much to be desired. The position of the cup cores, and the clamping pressure with which they are held, thus depends on the skill of the operator in tightening the clip properly while mounting the device. Too often, unfortunately, this skill is not present, and consistent esults are difficult to obtain on a mass pr duction basis. Since the inductance of the device is a function of the air gap and this in turn depends upon the manner in which the cup-core halves are assembled, a great deal of difficulty has been encountered in obtaining consistently good inductive devices at a reasonable cost.
Furthermore, if any of the units fail to meet test specifications, whether due to errors introduced by the assembly procedure itself or otherwise, the initial dirliculty is further compounded because disassembly and reassembly of these units again depends on the assemblers skill, takes a good deal of time, and is generally a complex procedure. In fact, it is often simpler and less expensive to discard an entire core-coil assembly rather than attempting to rework or correct these errors. Similarly, if a core-coil assembly deteriorates during operation, the problem of disassembling and reassembling the core elements in order "ice to repair them is also sufficiently troublesome that it is often simpler and less expensive to scrap the entire corecoil assembly. In any event, the excessive assembly time, high scrap and rework average all add to the manufacturing cost and the price of the device. Hence, a need exists for a mounting clip assembly for ferrite pot core inductive devices wherein the pot cores are firmly, effectively, and simply assembled prior to attachment of the entire device to the chassis or printed wiring board.
It is, therefore, a further object of this invention to provide a cup core mounting clip wherein the cup cores are firmly fastened to maintain a constant air gap without depending upon the skill of an operator to achieve the results;
Still another object of this invention is to provide a mounting clip for a cup-core assembly wherein the cup cores are firmly fastened together before attachment of the entire assembly to the supporting mediums;
Yet a further object of this invention is to provide a mounting clip for a cup-core assembly in which constant and consistent results are achieved in terms of the mounting pressure of the cup-core members and the air gap of the magnetic core assembly.
in addition to maintaining the proper air gap by applying a constant and fixed pressure to the cup-core halves, rotational movement between the two cup-core halves must be avoided in order to prevent any distortion of the flux path through the core members. In prior art mountingassemblies, it was quite common for the two cup-core members to be rotated relative to each other either during the assembly operation itself or later due to vibratory conditions to which the inductance device was subjected.
Hence, yet another object of this invention is to provide a mounting clip for a cup core inductive assembly wherein rotational movement between the cup-core halves is positively prevented;
A still further object of this invention is to provide a mounting clip for a cup-core inductive assembly wherein the cupcore assembly is insensitive to vibration.
ther advantages of the instant invention will become apparent as the description thereof proceeds.
In carrying out the various objects of the invention, a cup-core mounting clip is provided which has a deformable, arcuate bottom, two resilient side members or legs and a pair of flanges extending laterally from the side members. The cup cores are p essed against the arcuate bottom causing it to flatten out and snapping the flanged member over the top of the cup core thereby exerting positive and constant pressure on the two cup cores and preventing reiative rotational movement. After the cup-core halves have been thus assembled in the mounting clip, the mounting clip may be fastened by any suitable means to the chassis or printed wiring board which represents the supporting member for the inductance device.
The various features of this invention, which are believed to be new and novel, are set forth with particularity in the appended claims. The invention itself, however, may best be understood by reference to the following description when taken in conjunction with the accompanying drawing in which:
PEG. 1 is a perspective showing of the cup cores in an assembled position;
FIG. 2 is an exploded view of the assembly of FF. 1 showing the two cup-core halves and the mounting clip;
FIGS. 38 are schematic diagrams illustrating the mannor in which the cup cores are assembled in the clip and are useful in understanding the functioning of the clip.
FIG. 1 is a perspective showing of the cup cores secured in the novel mounting clip and the entire assembly ready to be fastened to a chassis or printed wiring board. The
a orns? v.23 assembly consists of two cup-core halves 2 and 3 mounted in a clip shown generally at l. The cores are firmly clamped in an abutting relationship by flanges 4 and 5 i which extend laterally from two resilient side members 6 and 7, attached to a resilient, deformable, arcuate bottom member, not shown in FIG. 1. Two mounting tabs 9 and are the means by which the entire assembly may be fastened to the chassis or printed wiring board. The mounting tabs Q and to contain suitable threaded screw holes 1i and 12 through which a fastening means is passed and attached to the mounting surface.
Cup cores 2 and 3, as may be seen most clearly in PEG. 2, are generally cup shaped and include center legs or projections l3 and 1d. The center legs, together with the side walls of the cup core, form an annular space to in which a non-metallic bobbin supporting one or more coils, not shown, is positioned. The non-magnetic bobbin and its associated coils surround the center legs 13 and 14 of the cup cores. The height of center legs 13 and is is less than the height of the core walls so that in the assembled position an air gap 15 is formed, which air gap controls the reluctance of the magnetic circuit formed by cup cores 2 and 3. Axial passages 17 are provided in the cores and are adapted to receive a small ferrite plunger 18 which is utilized as an adjusting device for the coil. The upper edges 1? of the cup-core wall are customarily machined to close tolerances so that a very tight fit is obtained when the two cup-core halves are pressed into abutting rel. on ship by the mounting clip. A plurality of openings provide a means for bringing the various coil leads into and out of the assembled cup core. t will be appreciated that because of these openings in the cup core the device is position sensitive since any relative rotation of the cupcore halves, which disturbs the alignment of openings 20, distorts the flux path through the outer walls of the cup core. As pointed out previously, in addition to the need for firm seating of the cup-core halves so that the proper air gap is maintained, the mounting clip must prevent relative rotational movement of the cup-core halves in order to avoid distortion of the flux path through the core.
The mounting clip l is constructed to achieve this desired result. As seen in PEG. 2, the mounting clip includes two resilient members or legs 6 and '7' which are shaped to conform to the cylindrical shape of the core. These legs extend from a deformable arcuate bottom member 21 which is flattened in assembly to firmly secure the cores. The arcuate bottom member 21 has a central cutout portion 22 for reducing the weight of the entire device and to permit adjustment of tuning slug ill") from the bottom side. The arcuate bottom 21 and flanges and 5 firmly secure the two cup-core halves in an abutting relationship. The arcuate member 211 is flattened dur ing assembly until flange members 4 and 5 snap over hcup cores thus maintaining them firmly under axial pressure and preventing rotational movement.
In the normal unflexed position the distance from the crown of the arcuate bottom member 21 to the top of the flange members 4 and 5 is less than the height of the as sembled cup cores 2 and 3. In order to assemble the two cup cores, the deformable, arcuate bottom member is fiattened until flange members 4 and 5 snap over the top of the cup cores thereby firmly holding the two cup-core members in an abutting relationship. it will be apparent from observation of the mounting clip of PKG. 2 that deformation or flattening of the arcuate bottom member 2 by the cup-core members produces an upward force against the bottom cup-core member along the axis of the core which is in contact with bottom member Similarly, it will be appreciated that the flange members and 5 produce a downward force against the top cup core at right angles to the force exerted by bottom 21, and that the force thus exerted by the bottom member 2.1 and flanges d and 5' maintains the two cup-core members in a firm abutting relationship.
Inasmuch as the force due to the deformed, resilient bottom member is along one axis and the force due to flange members and 5 is at right angles thereto, the pressure exerted on the two cup-core members is evenly distrib d around edges of the cup core insuring proper seathg of the members along the entire circumferonce.
The manner in which the cup cores are mounted in the novel mounting clip and the manner in which the mounting is achieved may be most easily understood by reference to FEGS. 3-8 which are schematic diagrams illustrating the mounting clip at various stages dunng the assembly process. Thus, PEG. 3 illustrates the two cup-core halves 2 and 3, shown in phantom, prior to their insertion in mounting clip l which is then in the unliexed position.
To insert cores 2 or 3 the two cup cores are placed together and the side me ers d and T of mount' clip 3. are
forced apart either by the ho ors or any suitable assembly tool and the cup cores partially inserted therein as illustrated in EEG. 4.
The cup cores 2 and 3 are pushed into the mounting clip until the bottom cup-core half rests against the crown of arcuate bottom member 21 of the clip. As may be seen in PEG. 5, cup core 3 makes tangential contact with the bottom member 21 along an axis extending into the plane of the paper. The total height of cup cores 2 and 3 is greater than the height of the clip from the crown of the arcuate member to tile flange 5 and 6 so that the ges do not extend over the cup core members. As pressure is exerted on the cup cores, a pressure shown by means of the arrow 24 of FIG. 6, bottom member .21 is partially lattened, and the flanges f5 and 6 move upward along the side wall until, as shown in FIG. 7, the bottom is flattended sufficiently for flanges d and 5 extend over the upper edge of the cup-core members. A slight additional increment of pressure on the cup cores flattens the bottom sutliciently for flanges i and 5 to snap over the top of the cup-core members into the final assembled position.
While a particular embodiment of the invention has been described and shown, it will, or" course, be understood that it is not limited thereto since many modifications and variations in the method and the circuit arrange ment for pairing out the invention may be made. it is contemplated that the appended claims cover any such modifications as forward in the true spirit and scope of this invention.
What is claimed and desired to be secured by Letters Patent of the United States is:
1. In a clip assembly for fixedly retaining two cylindrical cup-core halves in abutting relationship the combination comprising a deformable base having a substantially arcuate shape, a pair of resilient curved side members extending vertically from said base, said side members and said base deining a generally cylindrical space for receiving both of the cup-core halves in their entirety, coplanar flange members extending laterally from said side members, said flanges and said base cooperating to exert axial pressure on said cup-core halves to retain them in abutting relationship and to prevent relative rotation of the halves, the distance from the crown of said arcuate base in the undeformed state to said flange designed to be less than the height of the two cup-core halves whereby said flange members extend completely over said cup-core halves to exert pressure on the cup-core halves only who said base is deformed.
2. in a clip assembly for retaining two position sensitive magnetic elements in a fixed abutting relationship, the combination comprising a resilient base, bowed along one axis, a pair of resilient side members conformed to the shape of the elements to be retained extending from said base in a general parallel direction with said axis to define a space for completely receiving the elements to be retained and preventing relative movement therebetween, coplanar ilange members extending aterally from said side members for evenly distributing tie pressure around the elements to be retained, the distance between the bow of said base in the undeformed state and said flange members designed to be less than the total height of the magnetic elements thereby retained whereby said flange members snap completely over said elements in the assembled state to retain said members under pressure.
3. In a clip assembly, for retaining two cylindrical magnetic elements in a fixed abutting relationship, the combination comprising a generally circular, arcuate deform able base having a bow along one diameter of the circular base, a pair of arcuate resilient side members conforming to the cylindrical shape of the elements to be retained extending from said base generally in parallel to said bow to define a cylindrical space for completely receiving the elements to be retained and preventing relative movement therebetween, arcuate coplanar flange members extending laterally from said side members for exerting pressure on said members generally at right angles to that ex- References Cited by the Examiner UNITED STATES PATENTS 2,225,592 12/40 MacFadden 248--361 2,230,923 2/41 Barry 248-309 2,539,581 1/51 Holden 248361 2,541,828 2/51 Peck 248-300 CLAUDE A. LE ROY, Primary Examiner.
FRANK L. ABBOTT, Examiner.