US 3597711 A
Description (OCR text may contain errors)
United States Patent  In ento Joseph W. Buckley 3,200,355 8/1965 Dahlen 333/79 Sepulveda,ClliI. 3275.953 9/1966 Coda etal. 333/79  App]. No. 793,264 3,253,l98 5/l966 Garstang 317/242 Ski 1 3 2 Primary Examiner-Herman Karl Saalbach  Assi nee ln tti'nationll'lele bone and Telegra h Assismm Examiner c' Baraff g Corinna p p Attorneys-C. Cornell Remsen, Jr., Walter J Baum, Paul W. New York NY. Hemmmger Percy P. Lantzy and Thomas E. Kristofierson 54 REMQVABLE ELECTRICAL CONNECTOR ABSTRACT: The disclosure relates to an electrical connector FILTE filter assembly comprising a cylindrical core made of fer- 1 ch Dn ing Figs romagnetic material and an outer core of dielectric material 2 Us I which is coated by a conductive layer. A pair of conductive l5 C 333/79, Spring members having an Opening approximately the Same as 5 317/242, 339/64, 339/126, 339/258 that'of the ferromagnetic core are placed at either end of the [5(1)] 03h 7/14 two core members A conductive tube having a fl at one 1 It 0 Search 333/79, 70, end thereof which abuts one of the spring members is inserted 317/242; 339/196 64 through the spring members and the ferromagnetic core and  kdenncescmd the other end of the tube is then formed against the other spring member A plurality of inwardly extending tines are UNITED STATES PATENTS formed along the conductive tube for contacting a terminal 3,462,7l5 8/1969 Schor 333/79 member which can be inserted through the tube. The as- 3,456,215 7/1969 Denes 333/79 sembly provides a removable pi-filter.
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l 1 I I I Ir 1/ REMOVABLE ELECTRICAL CONNECTOR FILTER The invention relates in general to electrical connector fil ters and more particularly to removable filter elements for use in coaxial lines.
BACKGROUND OF THE INVENTION The use of RF (radio frequency) filter elements in circuits has become extremely common in numerous applications. For example, in numerous electrical systems, the embodying of RF filter components in one or more electrical connectors eliminates the necessity for a large amount of expensive shielding which would otherwise be required. To make the filter elements more versatile, it has become common practice to make such filters removable from a terminal so that if either the terminal or the filter requires replacement, the entire combination need not be replaced. The use of the removable filter assembly within the connector body requires that the terminal to connector assembly be simple, yet highly reliable. Heretofore, to eliminate the soldering of filter elements to a pin or spring, relatively complex arrangements were required. Further, as is apparent, the more complex the arrangement, the less reliable the contacting surface becomes. One such arrangement is the use of eyelets at the ends of the filter assembly tube which are soldered to the filter itself. In other arrangements, contacting surfaces are pen'ndnently mounted within the electrical connector body itself which are used to contact the surface of the element. Such arrangements are expensive to make and reliability problems in the soldering occurs.
In order to overcome the attendant disadvantages of prior art electrical connector filters, wherein the filter elements are soldered to the pin or the filter elements are soldered to attaching accessories, such as a split eyelet, the present invention utilizes an assembly which does not require soldering of the attaching accessories to the filter. Moreover, the arrange ment provides a reliable electrical contact to the ir'i'ner conducting surface of the filter element. Further, the arrangement is both simple and relatively inexpensive as compared to prior art filter assembly techniques.
SUMMARY OF THE lNVENTlON More particularly, the electrical filter comprises a tubular impedance element having a central aperture therethrough and an electrical conductive coating on its outer surface which is adapted to be connected to a suitable ground. One side of an electrically conductive spring member having a central aperture coaxial with the impedance element aperture abuts one end of the impedance element. A conductive tube comprises a flange portion at one end which abuts the other side of the spring member. Further, the tube is slidably insertable into the aperture with engaging means formed on the conductive tube which are adapted to engage a terminal pin insertable through the tube. Further, the other end of the conductive tube may be bendable to form a second flange at the other end of the impedance element and to abut against a second spring member, the impedance element, thus, being captivated between the flanges. Moreover, the engaging means may comprise inwardly extending tines formed on the conductive tube.
The advantage of this invention, both as to its construction and mode of operation, will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures.
BRIEF DESCRlPTlON or THE DRAWINGS FIG. I is an exploded view of the electrical connector filter assembly, constructed in accordance with the preferred em bodiment of the invention;
H6. 2 is a sectional view of the electrical connector filter assembly of FIG. 1 when mounted on a terminal;
FIG. 4 depicts the electrical connector filter assembly when mounted in a connector.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown in H0. i, an electrical connector filter assembly 12 in accordance with the invention. Referring to FIG. 2, the electrical filter comprises a cylindrical core 14 made of ferromagnetic material. Surrounding the core 14 but separated therefrom, is a second core of dielectric material, 16, having its inner surface coated by a conductive layer 18 and a conductive layer 20 which are separated by an airgap 21. The conductive layers 18 and 20 extend around the ends of the core and cover the outer end portion thereof. Further, a conductive layer 22 covers the outer central portion of the core 16 but is separated from the layers 18 and 20. As seen thus far, the ferromagnetic material forms an inductance for an RF filter and the core 16 forms a capacitor pair. The layer 22 is normally connected by suitable means to form a ground connection when the assembly is installed within a connector body.
The filter assembly further comprises a first conductive spring member 23 and a second conductive spring member 24 having central openings 25, 26, respectively, therein, the approximate diameter of the openings being the same as that of the opening in the core 14. The conductive spring members may be made of aconductive elastomer such as metal filled silicon rubber, a conductive mesh'such as lated metal wool, or a metallic spring. Further a conductive tube 28 whose outer diameter is approximately that of the inner diameter of the spring members 23, 24 contains a radially extending flange 32 at one end thereof. At approximately the central portion of the tube 28, a plurality of inwardly extending tines 34 are formed for contacting a terminal member 36.
In assembly of the filter, first the spring 24 is slipped over the tube 28 until it abuts the flange 32. Then the filter element formed of the cores l4 and 16 are slipped over the tube. Finally, the spring element 23 is slipped over the tube 28 and the end 33 of the tube adjacent the spring is then formed in place in a similar manner to the flange portion 32, thus, captivating the filter elements. The spring members on each end provide reliable electrical contact between the conductive layers 18 and 20 and the formed ends ofthe tube, respectively.
The RF filter assembly 12 provides a pi-section filter arrangement which is shown in FIG. 3. The conductor 38 represents the terminal 36 and the inductor 42 has the electrical effect of the ferrite core 14 mounted on the metal tube 28. The capacitors 44 and 46 are formed by conductive coatings l8 and 20 separated from the coating 22 by the dielectric tube 16.Thc spring members 23 and 24 together with the metallic tube 28 form the electrical connection between the terminal 36 and the capacitors, while the outer conductive coating 22 is connected to ground in operation. it should be pointed out, however, that the filter of FlGS. 1 and 2 are only an approximation of the circuit of FIG. 3 and not an exact duplication thereof.
The construction of the invention depicted herein includes a pair of capacitors although it should be understood, of course, that more or less may be employed. Further, the value of the capacitance can be varied by varying the type ofdielectric materials employed, the width of the dielectric ga and the area of the conductive coating. Moreover, with respect to inductance, it shouldbe understood that the amount of inductance obtained may be varied by varying the composition of the ferromagnetic material employed in the core 14 and by varying the size and configuration of the core. Also, it should be understood that variations are possible to provide only capacitance or inductance into a circuit.
The filter assembly as'depicted in FIGS. 1 and 2 can be conveniently slipped onto the terminal 36 and then the combined terminal and filter installed in a connector body. Further, the filter assembly also lends itself to being permanently installed in a connector body to permit the terminals to be removably As shown in FlG. 4, the filter assembly 12 is illustrated in an enlarged portion 52 of a bore 54 extending through a connector body formed of a front insulator 56, a rear insulator 58, and a ground plane 62. The outer conductive coating 22 on filter assembly 12 is electrically connected to the ground plane 62 by a grounding spring 64, The filter assembly 12 is confined within the connector body by an inner shoulder 66 formed in the front insulator 56 and an inner shoulder 68 formed in the insulator 58.
The connector terminal 36 is inserted into the filter assembly 12 through the conductive tube 28 and retained in the connector body by means of a retaining clip 74 having inwardly extending fingers 76 which engage the rear surface ofa shoulder 78 formed on the terminal 36. The terminal 36 may be removed by inserting a suitable tool (not shown) around the terminal to cause the fingers 76 to depress outwardly. The
, rear of the terminal 36 may be formed ofa socket 82 for connection to a conductor wire 84.
What I claim is: 1. An electrical filter assembly comprising: a filter element being generally tubular in shape and having an electrical conductive coating on its outer surface adapted to be connected to a suitable ground and having a central aperture extending therethrough;
first and second electrically conductive spring members having a central aperture, said first spring member abutting one end ofsaid filter element at one side thereof, said first spring member aperture being coaxial with said filter element aperture;
a conductive tube slidably insertable into said apertures and having a flange portion at one end thereof abutting the other side of said first spring member, the other end of said conductive tube being bendable to form a second flange at the other end of said filter element to abut against said second spring member, said filter element being captivated between said flanges; and
engaging means formed on said conductive tube adapted to engage a terminal pin insertable through said tube, said conductive tube forming an electrically conductive path from said filter element to said terminal member through said spring member.
2. An electrical filter assembly comprising:
a filter element being generally tubular in shape and having an electrical conductive coating on its outer surface adapted to be connected to a suitable ground and having a central aperture extending therethrough;
an electrically conductive spring member having a central aperture and abutting one end of said filter element at one side thereof, said spring member aperture being coaxial with said filter element aperture;
a conductive tube slidably insertable into said apertures and having a flange portion at one end thereof abutting the other side ofsaid spring member; and
engaging means comprising inwardly extending tines formed on said conductive tube adapted to engage a terminal pin insertable through said tube, said conductive tube forming an electrically conductive path from said filter element to said terminal member through said spring member.