US 3104145 A
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Sept. 17, 1963 9'. J. SOMERSET COAXIAL CONNECTORS 2 Sheets-Sheet 1 Filed Jan. 23, 1961 INVENTOR.
SIIQIERMAN J SOMERSET W ,Mm
Sept. 17, 1963 5. J. SOMERSET comm. CONNECTORS 2 Sheets-Sheet 2 Filed Jan. 25, 1961 INVENTOR. SHERMAN d. SOMERSET United States Patent "ice 3,104,145 COAXIAIL ONNECTORS hermau J. Somerset, Melrose, Mass, assignor to Gremar Manufacturing 30., Inc, Wakefield, Mass, a corporation of Massachusetts Filed Jan. 23, 196i, Ser. No. 84,346 4 Claims. (6!. 339-103) This invention relates to cable connectors and more particularly to miniature radio frequency coaxial cable connectors.
Coaxial cable of the type with which the present invention is concerned generally comprises a solid or stranded inner conductor, a flexible dielectric material surrounding the inner conductor, a Woven or braided flexible sheath of one or more layers of metallic material surrounding the dielectric material, and an outer insulating cover or casing. The latter may comprise a single layer of plastic, rubber, impregnated fabric or other material, depending upon the environment in which the cable is intended to be used.
Heretotore, many different [forms of miniature coaxial cable connectors have been devised. However, most or these have not been fully satisfactory. Some have been too cumbersome to assemble and disassemble or have been unduly complicated mechanically. Other types have been incapable oi splicing the cable to the connector with sufficient strength or have clamped it in a manner which causes rapid fraying and ultimate rupture of the sheath. Other disadvantages have been failure to provide effective sealing of the interior of the cable from the atmosphere. Protection from the atmosphere is necessary in order to prevent electrical break down and also to prevent corrosion and rotting. Penhaps the most common difliculty with conventional coaxial connectors has been the inability to obtain low voltage standing wave ratios as a standard result. Excessive reflected signal has been a common defect, due in part to the manner of splicing the cable to the connector and in part to the disposition of the elements of the connector which cooperate to secure it to the cable.
Accordingly, it is a major object of the present invention to provide an improved and novel coaxial connector which is mechanically simple and eflicient, is easy rto attech to a coaxial transmission line, provides a good hermetic seal for the portion of the cable contained therein, and is ott excellent electrical efliciency.
A further object of the present invention is to provide a coaxial connector having a novel construction lfOI providing firm and secure mechanical connection plus excellent electrical coupling between the connector and a coaxial cable.
A turther object of the present invention is to provide a coaxial connector having an improved cable splicer which not only functions as a splicing element for the metallic sheathing of the cable, but also is useful to flair the braid away from the cable, whereby to position the flaired portion of the braid for best possible clamping to the connector. The cable splicing element takes the place of the braid against the dielectric material and is designed to eliminate air or gas pockets within the connector in the area surrounding the cable dielectric, whereby to eliminate electrical reflections and obtain a satisfacrtory voltage standing Wave ratio.
A further object of the invention is to provide a novel coaxial line connector capable of easy and speedy assembly and which is electrically efficient at ultra-high frequencies.
Other objects and many of the attendant advantages of the present invention will become readily apparent from a review of the following detailed specification when conclamp element generally identified at 62.
dddlddd Patented Sept. 17, 1963 2 sidered together with the accompanying drawings in which:
FIG. 1 is a perspective view or a coaxial cable connector embodying the present invention;
FIG. 2 is a longitudinal sectional view of the same cable connector as attached to a coaxial cable;
FIG. 3 is an exploded perspective view of the assembly of FIG. 2, but with the cable omitted; and
FIG. 4 is an elevational view of a portion of the assembly of FIG. 2, with the cable splicing elements and a portion of the cable shown in section to illustrate a novel feature of the invention.
The illustrated connector comprises an elongated cylindrical body 2 which is provided with an interior thread 4 at one end and with a reduced section 6 at the other end. The reduced section 6 is provided with a peripheral groove 8 in which is mounted a resilient split locking ring it). Surrounding the reduced section 6 is a coupling nut 12 which is provided at one end with interior threads 14 and at the other end with an interior groove '16. The threads 14 permit the nut to be screwed onto a mating connector. The interior groove 16 is designed to receive the split locking ring 16-. Like peripheral groove 8, it is of rectangular cross-section. In this connection it is to be observed that the depth of groove 8 is suflicient to tully receive locking ring 10 when the later is compressed, thereby permitting coupling nut 12 to be slipped onto the reduced section 6. The ring will remain compressed by nut 12 while the nut is being slipped over the body 2. However, ring 10 will automatically snap into the groove 16 when the latter is in radial registration with groove 8. Once ring 10 has snapped into groove 16, it will act to rotatably hold together the nut and connector body 2.
In the region of reduced section 6, the body has an interior abutment or flange 18 which defines a central bore 2%) and provides two opposite shoulders 22 and 24. Shoulders 22 and 24 are provided with like diameter counterbores 28 and 3t). Adhesively secured within bore 2% is a plastic insulator 32 having an axial bore 34 which is adapted to receive a contact element 36. Fitting around insulator 32 is a contact element 38 having a plurality of resilient fingers 4:) which terminate short of the end face 4-2 of coupling nut 12. The contact element 38 is provided with an enlarged flange 44 which fits within counterbore 2%. Contact element 38 is maintained in place by staking shoulder 2-2 at a plurality of points so as to provide a [frictional grip between flange 18 and the contact element. Soft solder 46 is also added so as to improve the electrical contact between flange 18 and contact element 33.
A rubber sealing gasket 48 is positioned around contact element 33. This rubber gasket is cemented to shoulder 22. Preferably also it may be cemented to contact element 38. Also abutting insulator element 32 is a conductive metal bushing 50. This bushing is press fitted into counterbore 30.
With the exception of the contact element 26, the foregoing elements constitute a unitary sub-assembly. This sub-assembly is adapted to receive the aforesaid contact 26, a coaxial cable, splicing and sealing elements, and a cable clamping nut.
Bushing 5t) cooperates with shoulder 24 to provide a supporting surface for a cable splicer element generally identified at 54. As illustrated in FIGS. 2, 3, and 4, cable splicer 54 comprises an annular flange portion 56, a frusto-conical section 58, and a central opening 60. The radial dimension of the flange 56 is greater than the corresponding dimension of the frusto-conical surface 58. Cooperating with splicer 54 is a braid or sheath This clamp element 62 is an annular element Whose outer diameter a cylindrical surface 64.
is the same as that of splicer 54 except at the face which lies adjacent to the splicer where it is reduced to form The face which lies adjacent to splicer 54 comprises an annular surface as and a frusto-conical or tapered surface 63 which reduces in diameter to a central opening 7&9. The opposite face '72- of clamp element 62 has a counterbore 74 and comprises an annular ridge 76 of triangular cross-section. The annular ridge '76'is designed to fit within a V-shaped groove 78 formed in one face of a compressible gasket 80 made of rubber or some other suitable gasket material. The opposite face of the gasket is engaged by a metal washer 84. The latter is engaged by a cable clamping nut 36 which is threaded to mate with internal'threads 4. Nut 8d acts on the washer 84 to compress the gasket 8@ into tight sealing relation with clamp element r22, the latter in turn being forced toward splicer 54*.
The foregoing assembly is adapted to receive a coaxial cable generally identified'at 9%. This coaxial cable is of conventional construction and comprises a central conductor d2, a plastic (cg. polyethylene) dielectric 9d surrounding the conductor, a metallic braided sheath 96 surrounding the dielectric, and a plastic insulating cover 93 surrounding the metal sheath.
Nut 86, washer $4 and resilient gasket 8%? have central openings lilo, 102, and ms respectively, which are identical in diameter to' counterbore 74 of clamp 62., being sized so as to just accommodate the insulating cover 98 of the cable.
The central opening 70 in clamp is smaller than the diameter of the cable cover 98, but just large enough to accommodate sheath 96 of the same cable. The central opening so in splicer element 54 is sized just large enough to receive the dielectric 94 but not large enough to receive the metallic sheath 96. The central opening the metal bushing 50 is considerably larger than the diameter of the dielectric layer 94', whereby to accommodate an insulator bushing ill} which fits over the dielectric material 94-.
The shape and location of the tapered surfaces 58 and 68 of splicer 54 and clamp-i 62, respectively, are such that these surfaces are parallel and, when the annular surface 66 is separated from the flange portion 56 by a distance equal to the thickness of the cable braid, the perpendicuwill be gripped tightly; the portion of the sheath between the fr'usto-conical portion 58 and mating surface 635 will not be pinched. This condition is illustrated in FIGS. 2'
and. 4 by exaggerating the spacing between the sheath and frusto-conical portion 58. In practice, however, the difference in spacing is barely discernible to the naked eye.
The process of assembling the connector onto a cable is very simple and requires little time. First of all,'the outer insulation 98 is cut back to expose the braided sheath 96. Thereafter, the clamping nut b6, the clamping washer 84, and the sealing gasket 8% are slid onto the cable over the insulating cover 93. Next, clamp element 62 is slid onto the cable in such a way that the transversely extending flange 56 and annular surface 66 viously prescribed, its end may be bent back against cylindrical surface 64. Thereafter, the dielectric layer 9 is cut back a predetermined distance to expose some of the inner conductor 92, as shown in FIG. 4.
This inner conductor 92 is then tinned preparatory to receiving the contact element 36. Immediately after tinning, the insulating bushing 110 is slipped over the dielectric 94. Then the contact element 36 is slipped onto the inner conductor 92 and is secured thereto by solder. in this connection it is to be observed that contact element has an axial bore at its inner end to receive the conductor (as shown in broken lines in FIG. 2) and also has a lateral opening 114 in which solder is deposited to secure it to the conductor. V
" Thereafter, the end of the cable bearing contact 36 is viously, because of the spacing between the two tapered 7 surfaces 5? and 68, all or" the clamping action is accomplished between the transversely-extending surfaces 56 and 66. The tapered sections serve simply to lift the braided sheath away from the dielectric 94 in a gradual and easy manner, thereby preventing the sheath from fraying. At the same time, their close but non-clamping spacing substantially eliminates air or gas pockets between the splicer and clamp elements, thereby avoiding any significant electrical reflections and resulting in voltage standing wave ratios of most satisfactory values, e.g., 1.2 or less up to frequencies as high as 'l0,000 megacycles. In this connection it is to be observedalso that relatively large contact areas between clamp 62, spliccr 5d, flange l8 and bushing assure full and dependable electrical connection between braided sheath 96 and contact element 33. I V
In addition to providing improved electrical performance the aforesaid construction has the advantage of pro viding an excellent hermetic seal for the exposed portions of the coaxial cable. Rubber gasket 80 snugly surrounds the cover 98 of thecable and thereby provides an herm tic seal for the interior of the connector.
Another notewonthy advantage of the foregoing construction is the strength of the connection between the connector and the cable, due to a major extent to the fact [that the braided sheath 96 is clamped between llWO transversely-extending mated surfaces instead of between two oblique or two coaxial surfaces. Not only does this strong connection preventthe cable and connectorfrom being pulled apart in use, but it also reduces electrical noise due to the inability of the braided sheath to move a relative to the splicer and clamp elements.
end of the insulating cover 98 fits into the counterbore 74m Then the braided sheath 96 is cut off to a length beyond the end of the insulating cover 93 equal to approximately the axial length of bore 79, and the linear length of frusto-conical surface as and the radius of ancritical. If it is cut slightly longerthan the amount pro-- ious types of coaxial connectors.
A further important advantage of the foregoing construction is that the entire assembly can be rapidly serviced in the field without special tools. The cable can be pulled free of the connector body simply by unscrewing clamplug nut 86. Replacement of contact element 36 is a simple soldering job.
It is to be noted that the invention is applicable to varthe coaxial connector to have contact elements like those shown at 36 and 38, or even a coupling-nut such as coupling nut 12. The connector may the of other constructions, including cable or panel jacks, straight or right angle cableplugs, panel receptacles, and right angle or T adapters. The invention may be embodied in these other types of connectors without departing from the principles hereinabove'described. It is also to be understood that the invention is not limited to miniature-size connectors but is applicable as well to larger size connectors.
ilt is not necessary for Obviously, many modifications and variations of the invention are possible in view of the above teachings. Therefore, it is to be under-stood that the invention is not limited in its application to the details of construction and arrangement of parts specifically described or illustrated, and that within the scope of the appended claims, it may be practiced otherwise than as specifically described or illustrated.
What is claimed is:
1. A connector for a coaxial cable which includes a central conductor, a conductive sheath, an inner layer of insulation interposed between said conductor and sheath, and an outer layer of insulation covering said sheath, said connector comprising a hollow body open at both ends and having an abutment formed therein, a cable splicing disc within said body comprising an annular flange portion and a frusto-coni-cal center portion having a center hole sized to accommodate said inner layer of insulation but not said sheath, said flange portion sized to engage said abutment, said firusto-conical center portion tapering inwardly away from said abutment, a cable clamping disc within said body, said cable clamping disc having opposite end faces with one end face disposed adjacent to said splicing disc, said one end face comprising an outer annular surface and an inner frusto-conical surface defining a funnel-shaped depression to accommodate the frustoconical center portion of said splicing disc, said annular surface disposed substantially parallel to said annular flange portion, said frusto-conical center portion and said frusto-conical surface sized so as to be spaced from one another when said annular flange portion and said outer annular surface engage each other, said cable clamping disc having a central bore sized to accommodate said sheath but not said outer layer of insulation, a resilient annular gasket Within said body adjacent the opposite end face of said clamping disc, said gasket having a center hole sized to accommodate said outer layer of insulation, and means cooperating with said abutment for compressing together said gasket and discs, whereby a cable inserted within said body may have the end of its sheath secured tightly between said annular flange portion and said outer annular surface While the portion of said sheath between said frusto-conical center portion and said frustoconical surface is substantially free of any clamping force.
2. A coaxial connector for a selected coaxial cablehaving a conductive sheath surrounding an insulated condoctor, said connector comprising a hollow body, a clamp disc within said body, said clamp disc having an end face comprising a first outer annular surface and an immediately adjacent inner frusto-conical female mating surface, said clamp disc also having a central hole sized to accommodate the conductive sheath of said selected cable, a splicer disc within said body, said splicer disc having a peripheral flange with a second outer annular surface and an inner frusto-conical male mating section, said first and second annular surfaces disposed at substantially right angles to the axis of said body, said male section having a center hole sized to receive the insulated conductor of said same coaxial cable, said female surface and male section sized so as to be spaced from one another when said annular surfaces engage each other, whereby when the cable sheath of said same cable is clamped between said annular surfaces, the portion of said sheath between said female surface and male section will be substantially free of any clamping force, and means for forc- '3 ing said discs toward each other and to hold them stationary Within said hollow body whereby to clamp them to an interposed cable sheath.
3. A connector for coaxial transmission lines of the type comprising a central conductor, a conductive sheath, an insulating sleeve intermediate said conductor and sheath, and an outer covering of insulating material, said connector comprising a hollow connector body having an internal shoulder and means defining a coaxial bore through said shoulder, a splicer disc abutting said shoulder, said splicer disc comprising an outer right-angle annular flange section and a solid frusto conical inner section having a coaxial center hole slightly larger than the intermediate insulating sleeve of a given coaxial line but smaller than the sheath of said same line, said inner se tion tapering away from said shoulder, a clamp disc adjacent to said splicer disc, said clamp disc having a center hole just large enough to accommodate the sheath of said same coaxial line, said clamp disc having an end face comprising an outer right-angle annular surface and an inne frusto conical surface which defines a countersink for its center hole, said frusto-conical section and said frusto-conical surface sized to be spaced from one another when said annular flange section is engaged by said annular surface, whereby When the sheath of said given line is clamped between said annular flange section and said annular surface, that portion of the sheath which extends between said frusto-conical section and said frustoeconical surface will be relatively free of any clamping force while fully filling the space between said frustoconical section and said frusto-conical surface, and releasable means cooperating with said shoulder to force said splicer and clamp discs toward each other.
4. A coaxial connector for a selected coaxial cable having a conductive sheath surrounding an insulated conductor, said connector comprising a clamp disc and a splicer disc, said clamp disc having an end face comprising a first outer annular surface and an inner frusto-conical female mating surface, said clamp disc also having a central hole sized to accommodate the conductive sheath of said selected cable, said splicer disc having a peripheral flange with a second outer annular surface and an inner frusto-conical male mating section, said male section having a center hole sized to receive the insulated conductor of said same cable, said female surface and male section sized so as to be spaced from one another when said first and second annular surfaces engage each other, whereby when the end of the sheath of said cable is clamped between said annular surfaces, the portion of said sheath between said female surface and said male section will be substantially free of any clamping force, and means for forcing said discs together 'and to hold them fixed relative to each other whereby to clamp them to an interposed cable sheath.
References Cited in the file of this patent UNITED STATES PATENTS 2,425,834 Salisbury Aug. 19, 1947 2,490,596 Morris Dec. 6, 1949 2,785,385 Figueira Mar. 12, 1957 2,804,601 Harthman et al. Aug. 27, 1957 2,870,420 Malek Jan. 20, 1959 3,040,288 Edlen et a1. June 19, 1962