US3466590A

US3466590A - Grounding device in an electrical connector

Info

Publication number: US3466590A
Application number: US697508A
Authority: US
Inventors: Robert T Sylvester
Original assignee: US Atomic Energy Commission (AEC)
Current assignee: US Atomic Energy Commission (AEC)
Priority date: 1968-01-12
Filing date: 1968-01-12
Publication date: 1969-09-09
Anticipated expiration: 1986-09-09

Description

Sept. 9, 1969 R. 1'. SYLVESTER GROUNDING DEVICE IN AN ELECTRICAL CONNECTOR Filed Jan. 12. 1968 Robert 'IZSylves'rer INVENTOR.

United States Patent 3,466,590 GROUNDING DEVICE IN AN ELECTRICAL CONNECTOR Robert T. Sylvester, Albuquerque, N. Mex., assignor to the United States of America as represented by the United States Atomic Energy Commission Filed Jan. 12, 1968, Ser. No. 697,508 Int. Cl. H01r 3/04, 13/46 U.S. Cl. 339-14 3 Claims ABSTRACT OF THE DISCLOSURE An electrical connector with contact elements having in the periphery of a first mating portion shell an annular groove with overlying marginal lips and an annular grounding spring retained in the groove by edges underlying the groove lips, the grounding springhaving an arcuate intermediate section outwardly maintaining the underlying edges and extending beyond the periphery of the first mating portion shell for electrical contact with a second mating portion prior to engagement of the contact elements.

Background of invention Electrical connections for coupling multiconductor cables generally include plug and receptable mating halves or portions with generally centrally located primary contacting elements and an elecrically conductive outer shell for shielding or grounding. The conductive shell around the plug portion may be a barrel-like member which insulatively contains the primary contacting elements, and

fits into or mates with an annular groove between the receptacle outer conductive shell and an insulative insert carrying mating primary contacting elements. The accepted manufacturing tolerances for the plug and receptacle shells are such that the outer periphery of the plug conductive shell may vary from the inner periphery of the receptable shell by a few thousandths of an inch. Thus the plug conductive shell may be first received in the receptable shell in a loosely fitting manner providing poor grounding and shielding through the connector body. In some circumstances a loose fit may not be detrimental to circuit operaion, but where an electromagnetic field is present, such as from radar which produces radio frequency energy, a difference of electrical potential may exist between circuit components within the field. Thus when the plug and receptacle portions are mated there may be a discharge or are between the principal contacting elements which may damage or affect the connected circuitry if the outer conductive shells are not first adequately grounded together.

Prior attempts to adequately ground a connector have included grounding elements welded, soldered, crimped, etc. to one connector half for contacting the second mating half. There prior devices have in some instances been used at relatively low temperatures because welded and soldered joints may tend to weaken and possibly fail at elevated temperatures and a crimped joint could possibly loosen on thermal expansion of its constituent parts. Further problems arose when it became desirable to produce connectors of materials such as aluminum which are difficult to weld or solder. These prior devices have been subject to the objection that means, such as keys and keyways, provided to align or orient the primary contacting elements could interfere with or interrupt the grounding elements such that inferior shielding or grounding would result if a large number of such as keys and keyways were required.

"ice

Summary of invention Therefore it is an object of this invention to provide anew and improved grounding element in an electrical connector.

It is a further object to provide a grounding device which nearly completely encompasses the principal contacting elements and is normally wiped clean with each connection operation.

Various other objects and advantages will become apparent from the following description of one embodiment'of the invention.

As shown, the invention is a grounding device for use in an electrical connector having mating primary contacting elements insulatively encompassed by conductive shells with slideably mafing surfaces comprising a continuous groove circumscribing a mating surface of one of said electrically conductive shells said groove having an intermediate raised surface bounded by continuous spaced apart marginal lips overlaying a recessed bearing portion of said groove, a generally annular grounding spring retained in said groove by said marginal lips having an intermediate arcuate section extending beyond the surface of said conductive shell for electrically connecting a mating connector half, the outer margins of said grounding spring electrically contacting and bearing on the outer margins of said recessed bearing portion of said groove underlying said marginal lips and said arcuate intermediate section supported by said intermediate raised portion of said groove when connected to a mating connector half.

Description of drawings FIG. 1 is a partially cutaway view of an electrical connector half embodying the present invention and a typical mating connector half.

FIG. 2 is a cross-sectional View of an electrical connector half of FIG. 1 along line 2-2.

FIG. 3 is an enlarged sectional fragmentary view showing in greater detail a grounding spring segment.

Detailed description One embodiment of the present invention is illustrated in FIGS. 1 and 2 wherein an electrical connector plug portion 11 incorporating the present invention is shown aligned with a mating socket or receptacle 13. The plug portion 11 includes an electrically conductive shell or barrel section 15 which may slideably mate or fit along outer surface 16 into an electrically conductive receptacle shell or hollow portion 21 along a corresponding inner surface 22 of the receptacle 13. An insulated insert or core 27 may be generally centrally disposed within the recep tacle shell 21 but radially spaced from a portion thereof to form an annular groove 20 for receiving barrel section 15. Insert 27 may carry one or more primary electrical contacts 31 which may mate with corresponding primary contacts 29 carried by a generally centrally disposed insulated insert or core 25 within barrel section 15. The conacis 31 are shown as sockets in receptacle portion 13 for receiving contacts 29 shown as pins in plug portion 11, but it will be clear that this arrangement may be reversed or other known types of mating contacts may be used.

The barrel section 15, as shown, may include conventional contact aligning means, such as axially extending keys 17 extending radially from surface 16 which align with cooperating axially extending keyways 19 formed within the surface 22 of the mating receptacle 13 to properly orient the primary contacts. The keys and keyways may be provided on either the plug or receptacle or in mixed combinations thereof extending in either straight or helical paths depending on the desired operation.

An outwardly extending peripheral shoulder or ridge 23 may be formed on barrel section at a suitable longitudinal location to limit the penetration of the barrel section 15 into receptacle shell 21 and groove 20. Secure connection between the plug and receptacle portions may be provided by a threaded collar or coupling ring 39 having an inwardly extending flange which abuts shoulder 23 and which may threadably engage a correspondingly threaded surface 41 on receptacle portion 13. Both the plug and receptacle portions may also include a threaded surface such as 33 and 35 for facilitating engagement of an electrical cable having a plurality of conductors to the connector portions with the conductors suitably connected to

contacts

29 and 31.

A continuous recessed surface or groove 37 may be formed or machined in a suitable manner known in the art in the surface 16 about the periphery or perimeter of electrically conductive shell or barrel section 15. Recess or groove 37 may be cut or continued through keys 17, which extend radially outwards from the surface 16 of the barrel section 15, without interfering with the contact orientation function of the keys. Groove 37 may have passages or slots 43 which serve as load bearing portions (shown in greater detail in FIG. 3) undercut below the peripheral or outer surface 16 of barrel section 15 to provide a pair of continuous overlying flanges or lip portions 45 along each side of groove 37. Intermediate and protruding radially outwardly beyond the bearing ortions of slots 43 in groove 37, may be a raised portion or grounding spring support surface 47 which remains recessed below the outer surface of barrel section 15. The raised portion 47 may smoothly rise outwardly from the margins 43 with generally obtuse angles or curves so as to provide a form maintaining support for the overlying grounding spring to be described below.

The grounding spring or element 49 may be formed of electrically conductive flat spring material or stock having a width less than the width of the recessed surface 37, but in excess of the width separating overlying lip portions 45. The flat spring material may be contoured widthwise to form a curved, hereinafter referred to for convenience as arcuate, intermediate section 51 bounded by marginal or edge bearing sections 55. Transverse or widthwise slots 53 may be cut generally transversely across the arcuate section 51 and terminating at or in the marginal sections 55 but stopping short of the distal or terminal edges of the grounding spring 49. Slots 53 may be longitudinally spaced apart along the grounding spring 49 to provide a plurality of arcuate spring segments (FIG. 1) between the slots to render the grounding spring flexible for shaping into a desired configuration around the periphery of barrel section 15 such as the annular configuration shown in FIG. 2. Arcuate intermediate section 51 may be initially shaped by conventional cold pressing or other means or later deformed inwardly along marginal sections when the grounding spring 49 is assembled into recessed groove 37. After assembly, the grounding spring 49 may be formed or reformed in a suitable manner, such as by rolling with radially inward pressure on the arcuate intermediate section 51 to expand the grounding springs relaxed width to exceed the distance or width separating lip portions 45 and thus lock or retain the spring 49 within groove 37 The arcuate intermediate section 51 of the grounding spring 49 may extend radially beyond or above the external surface or periphery of barrel section 15 and beyond the circumference of surface 22 of shell 21, as shown. The grounding spring may overlie the intermediate raised portion 47 of the recessed groove 37 so that when grounding spring 49 is constricted by pressure against surface 22 of shell 21, the raised portion 47 may provide support and a spring flexure limit for the arcuate intermediate section 51. The distal edges of marginal or edge bearing sections 55 of the grounding spring 49 may be spaced from the distal edges of the marginal bearing portions 43 of recessed surface 37 such that these distal edges will not abut and limit constriction of the spring. The length or perimeter of the grounding spring 49 may be slightly less than the circumference or perimeter of the recessed groove 37 so that a small gap 52 (FIG. 2) may be provided between the ends of grounding spring 49 retained in groove 37 to allow for a shorter perimeter or constriction of the spring.

When the plug 11 and receptacle portions 13 are mated the peripheral internal surface 22 of the receptacle shell 21 may wipe across and constrict radially inward the portion of the arcuate intermediate section 51 extending above the peripheral surface of barrel section 15. The marginal edges 55 of the grounding spring 49 will consequently bear against and across the bearing portion of the slots 43 in groove 37 making good, clean electrical contact there-with in a wiping or sweeping motion. The arcuate section 51 resists flexure and constriction establish a firm and clean electrical connection between the barrel section 15 and the receptacle shell 21 through grounding spring 49.

The grounding spring 49, barrel section 15, and receptacle shell 21 may be composed of electrically conductive materials such as copper, beryllium, aluminum or silver, and may be cadmium plated if an improved electrical contact surface is desired especially on connector parts composed of such as aluminum which normally may be coated with an insulative aluminum oxide film.

Even though the connector components have been shown in an annular configuration, any closed or nearly closed configuration may be used. Also, the grounding spring 49 and retaining groove 37 have been shown as part of the plug portion 11 on the external surface of the barrel member 15, however it will be clear that the grounding spring may be made a part of the receptacle portion 13 such as at the inside surface or perimeter 22 of the receptacle shell 21. In the latter configuration, it may desirable to position the keys on shell 21 rather than on barrel member 15 so as not to interfere with the operation of the key and keyway aligning means.

The invention provides an electrical connector having a new and improved grounding device. By providing grounding contact between the plug and receptacle shells prior to mating of the primary contact elements any electromagnetically induced potential on any portion of the connecting circuitry may be equalized without discharge or damage to the circuit. The grounding spring almost completely encompasses the connector circumference to maximize grounding contact, minimize possibility of arcing at ungrounded points on the connector periphery during the coupling operation and provide an encompassing electromagnetic shield about the primary contacts after the connector halves are assembled. The grounding spring is mechanically connected to the connector shell by locking its edges under overlying lips of a peripheral groove. This construction provides a ground ing shield suitable for a high and broad temperature ranges as there are no solder or weld joints to weaken at high temperature or crimped joints to fail on material expansion. By providing a raised portion beneath the grounding spring, it may not be unnecessarily stressed when constricted and may consequently have a long life. Furthermore the grounding device of this invention is especially useful with aluminum connectors which are difficult to weld or solder.

By disposing the keys for orienting the primary contacts only on the connector half having the grounding spring and recessed surface of the present invention, and disposing the mating keyways only on the other typical connector half, the grounding springs need not be interrupted but may pass through gaps formed in the keys allowing a large number of alignment keys to be used without breaking the continuity of the grounding spring.

It will be understood that various changes in the details,

materials and arrangements of the parts may be made by those skilled in the art within the scope of the invention.

What is claimed is:

1. In an electrical connector mating portion having a contacting element and an annular electrically conducting shell encircling said element and insulatively spaced therefrom, a continuous recessed surface disposed about a periphery of said shell having an intermediate raised portion bounded by a pair of continuous spaced apart undercut bearing portions with each of said undercut bearing portions overlaid by a continuous lip portion, spring means coextensive with said continuous recessed surface having an arcuate intermediate section overlying but spaced from said raised portion and bounded by a pair of spaced apart bearing sections, the width of said spring means being normally less than that of said recessed surface whereby distal margins of the bearing sections are normally spaced from distal margins of the hearing portions, said sections projecting beneath said. lip portions and resting against said bearing portions, said arcuate section having a plurality of of transversely extending spaced apart slots throughout the length of the spring means and said arcuate section projecting beyond adjacent surfaces of said shell, said raised portion of the recessed surface serving to support the arcuate intermediate section of the spring means upon suflicient constriction thereof.

2. The electrical connector mating portion of claim 1 wherein there is provided a raised alignment key on said periphery of said shell, said key having a first section axially extending away from said recessed surface from one of said lip portions and a second section axially extending away from said recessed surface from the other of said lip portions.

3. The-electrical connector mating portion of claim 1 wherein said conducting shell is composed of aluminum and there is provided a cadmium coating on said shell and said spring means.

References Cited UNITED STATES PATENTS 3,128,138 4/1964 Noschese 339-14 3,136,593 8/1964 Ehrman et a1 339-14 X RICHARD E. MOORE, Primary Examiner US. Cl. X.R.