US 3384703 A
Description (OCR text may contain errors)
y 1968 E. w. FORNEY, JR, ET AL 3,384,703
coAxIAL CONNECTOR 3 Sheets-Sheet 1 Filed May 26, 1964 IN VEN TOR.
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May 21, 1968 E. w. FORNEY, JR.. ET AL COAXIAL CONNECTOR 3 Sheets-Sheet 2 Filed May 26, 1964 INVENTOR. EDGAR \A/ILMOI" Fonusy, In. "RKHARD SHURE HQGENmoBLER BY & n; w y i z United States Patent 3,384,703 COAXIAL CONNECTOR Edgar Wilmot Forney, Jr., Harrisburg, and Richard Shure Hogendobler, Camp Hill, Pa., assignors to AME Incorporated, Harrisburg, Pa. Filed May 26, 1964, Ser. No. 370,204 6 Claims. (Cl. 174-75) This invention is directed to a coaxial connector which is crimpable to coaxial cable of the type used for communication channels, such as, distributing closed circuit television signals.
The specialized cable developed for transmission of communication signals of higher frequencies generally includes a center conductor surrounded and supported by a dielectric material, such as, foamed Teflon or polyethylene, in turn, supported by a relatively heavy tube of conductive metal forming the cable outer conductor, the tube itself being surrounded by a tough, thick, plastic sheath. This relatively heavy cable construction is necessitated by the mode of energy transfer which becomes very lossy if the cable dimensions are varied from the cable specification, as, for example, when the cable is slightly deformed such that the outer conductor is more closely spaced to the center conductor than in other regions. This would occur in a bend of the cable if it were of a lighter construction.
On the other hand, the heavy construction makes such cable particularly difiicult to terminate with standard connector constructions. The usual dilemma is that if the termination meets the electrical requirements by maintaining a proper spacing throughout the connection then it is not sufficiently strong mechanically to withstand the loads to which the cable subjected, or if the cable is made sufficient mechanically, it has electrical shortcomings. As a further problem, the relatively heavy construction of the cable in conjunction with its being filled with a solid dielectric such as foamed polyethylene or Teflon, makes the usual assembly procedures more tedious and requiring of the use of skilled labor than with other and simpler cable constructions.
Accordingly, it is an object of the present invention to provide a connector for coaxial cable of the type having a solid foamed dielectric material surrounded by a relatively heavy metal tubing which provides an electrical and mechanical termination of characteristics equal to approaching the characteristics in the cable itself.
It is a further object to provide a coaxial connector construction which is rapidly installable on semi-rigid coaxial cable.
It is yet another object to provide a novel coaxial connector sleeve and ferrule assembly for use with coaxial cable.
It is an object to provide a connector sleeve construction and method of assembly to coaxial cable which minimizes disturbance to cable dielectric and electrical discontinuity.
Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there are shown and described illustrative embodiments of the invention; it is to be understood, however, that these embodiments are not intended to be exhaustive nor limiting of the invention, but are given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.
In the drawings:
FIGURE 1 is a perspective showing the connector of the invention installed on a coaxial cable and crimped thereto;
FIGURE 2 is a section of the coaxial connector of the invention showing the center pin member crimped to the center conductor of coaxial cable;
FIGURE 3 is a perspective of the connector crimping sleeve extension of the invention;
FIGURES 4 and 5 are perspective showing an end of the coaxial cable before and after stripping procedures, respectively;
FIGURES 6 and 7 are sectional views showing the insertion procedures for inserting the sleeve extension of the connector of the invention within a cable;
FIGURE 8 is a sectional view showing the sleeve extension of the connector of the invention inserted and crimped to the cable by a ferrule member in conjunction with details of a novel O-ring assembly which is part of the invention; and
FIGURE 9 is a perspective of the novel O-ring outer sleeve.
Referring now to FIGURE 1, a coaxial connector 10 is shown terminating a coaxial cable 12, the joint being formed by the connector ferrule and its engagement through crimping as at the crimp C to the cable outer conductor.
The forward end of 10 is adapted to make this a complementary end for a connector half not shown which may be joined in an identical fashion to a further cable such as 12 or secured to some equipment to which the cable shown in FIGURE 1 is to be terminated.
The cable construction is shown in FIGURES 4 and 5 to include a relatively thick outer covering of dense plastic-like material 14, surrounding an outer conductor 16, which is a metal tubing, such as, aluminum or copper filled with a solid foam polyethylene dielectric material 18. The dielectric material 18 supports a center conductor 20, which is typically solid copper rod. In accordance with the present invention, the cable is first severed with a transverse cut being made as in FIGURE 4 and then stripped to expose a length of the center conductor 20 and a length of the outer conductor 16, such lengths :being related to the design of the connector shown in FIGURES 2 and 6 whereby the portions fit within and over, respectively, portions of the connector.
The connector 10 includes a central body member 32 having a rear sleeve extension 34 which is adapted to serve as a back-up member against crimping pressures and as a means to which the outer conductor 16 is terminated to .form the outer transmission path of the connection. The sleeve 34 extends for a considerable length, preferably a length greater than the diameter of cable, the outer conductor 16 and includes at its rear end a sharpened edge 36 having an internal bevel 38 disposed at an angle A with respect to the surface of 34 around the periphery of the extension. This angle A is held to a relatively small value to define a sharp cutting edge at the rear of the extension for purposes to be described hereinafter. The extension 34 is held to be of a thickness which is just enough to resist being deformed during the crimping operation and is, in terms of the thickness of the outer conductor, preferably thinner than such and in any event as thin as possible, considering its function in linking the cable to the conductor electrically and mechanically. Disposed about the surface of 34 are a series of V-shaped indentations 40 which serve to break up the oxidation deposits which may exist on the inner surface of the outer conductor 16 of the cable so that a good electrical connection is assured between the conductor 16 and the extension 34. At the point where the outside surface of extension 34 joins the main body of 32 is a gasket 35 of resilient and elastic material preferably of a size wherein, when slipped over the extension, it will remain in position to avoid the requirement for separate loose pieces during shipment and prior to use.
Extending along the interior of 34 is a bore shown as 42, which is approximately equal to the inner diameter of the outer conductor 16, less twice the thickness of the material of 34. Bore 42 flares outwardly within the body of 32 to define a bore 44 and then continues again forwardly of that into a bore 46 and to a bore 50. Between the bores 44 and 46 is defined a step and face 48 and between the bores 50 and 46 is defined a step and face 51. The bore 44 is somewhat larger than the inner diameter of the outer conductor 16 to compensate for the larger diameter of the inner conductor formed by a portion of the central pin member. This is to reduce electrical discontinuities. The spacing between the inner surface of 44 and the outer surface of portions of the central pin may he arrived at by standard procedures wherein the characteristic impedance of the section extending along 44 is adusted to approximate the characteristic impedance of the cable. Fitted within bore 46 is a dielectric plug shown as 52, which is seated against 48. The plug 52 includes a central bore housing and supporting the connector central pin member, The bore 50 accommodates a forward spring shell '56 which is flanged as at 54 and secured within 50 against the face 51 to lock the plug 52 against relative forward movement. The inner face of 52 is positioned relative to the body 32 such that with the pin member 70 secured to the center conductor 20 the cable may be worked forwardly until 70 is stopped by 52 to thus position the connector during assembly. The member 56 is relieved along its surface in an axial sense to define in dividual spring members which cooperate with complementary portions on the half not shown. Sleeve extension 34 is housed within a metallic sleeve 39 which is formed inwardly as at 41 to lock 34 within the connector assembly. At the opposite end of 39 there is an annular recess shown as 45 and a ring 64 which extends outwardly into a groove 62 of a forward member 60 internally threaded as at 66 to cooperate with the complementary jack or receptacle member for the connector. Member 39 is, thus, locked to 60 and to 34 to form a structurally integral assembly.
The central pin member 70 includes a sleeve portion 72 adapted to receive the end of the center conductor 20 and be crimped as at C thereto. The sleeve 72 is joined to a reduced portion 74 which, in turn, is beveled as at 76 to assist in the mating operation with a complementary connector half. The cooperation between '70 and plug 52 to resist or limit the forward axial movement of the pin relative to the connector assembly is important for reasons which will be covered hereinafter relative to assembly of the device on the cable.
FIGURE 3 depicts the general configuration of extension 34. The use of a member of this configuration has been found to be helpful in covering a relatively wide range of components with this same member. With the member 34, a given cable may be terminated to forward portions which are larger or smaller to connect with larger or smaller cables, the portion 39 being of a proper diameter.
Turning now to the assembly and method which is permitted by the above construction, FIGURES 4 and show the preferred preparation of the cable to the point shown in FIGURE 5 with a portion of the center conductor extending forwardly and a portion of the outer conductor 16 extended forwardly and free of the outer protective sheath 14. As a next step the central pin member 70 is fitted onto 20 and crimped thereto, Thereafter,
with the ferrule member 80 placed over 34, the outer conductor 16 of the cable, the connector is held with the cable secured positioned in the manner shown in FIGURE 5 and with the beveled portion and cutting edge defined by 38 being inserted just inside the outer conductor 16 of the cable. With the connector and cable so positioned, the connector is then forced inwardly with a turning motion applied therto such that the cutting edge 38 bites into the dielectric material, forcing the dielectric down within bore 42 and breaking its cleavage to the inner surface of 16 without causing spaces or voids, Continued force applied to the connector along with a slight rotation or twisting thereof will work the extension 34 down to the position shown in FIGURE 7 and then completely within, in a position shown in FIGURE 8, with the conductor 16 abutting against the gasket 35. With practice, this procedure takes only a few seconds, the thinness of 34 in conjunction with the knife edge and acting to facilitate the insertion by forcing the dielectric downward into and along 42. Thereafter, a crimp may be applied to the ferrule member 80 as indicated by numeral C in FIGURE 8. The crimp C is preferably an O-type crimp applied in three spaced circumferential areas over the length of the extension 34, the inner crimp acting to compress and deform gasket 35 to seal the connector against the entry of gas, vapor or contaminannts at that point. The change in diameter of the transmission path of the cable and connector effected by a thickness of 34, will, of course, present a discontinuity but the thinness of 34 will tend to minimize this discontinuity and the connector has been found to be quite satisfactory for uses in the lower ranges of so-called high frequency communications, such as, about 225 megacycles. The presence of the continuous cable dielectric without voids extending from the cable up well into the connector is preferable to certain prior art approaches wherein the dielectric is cut off before entry into any portion of the cable. 7
Turning to yet a further aspect of the invention and to the ferrule member 80, FIGURE 8 shows that at the rearward end thereof is included a radial flange extending outwardly shown as 82, which houses an O-ring or gasket of elastic material 90. In normal use, the gasket is selected of dimensions such that it rests within 82 and has an inner diameter slightly smaller than the outer diameter of the outer conductor 16. This then operates to seal the connection formed against the entry of contaminants through the outer end of the ferrule 80. The gasket 90 is held in position by an outer member 84, which includes on its inner surface, a flange tapered inwardly as at 86 to facilitate its insertion over 82. The member 84 further includes an inwardly disposed flange portion 88 which operates to lock and hold the gasket 90 within 82. It is contemplated that the member 84 be made of a molded plastic-like material having elastic properties such that the member is readily deformable so it may be snap-fitted over 80. As an additional point by having member 84 of an insulating material any problem which might occur by the use of copper, brass or the like, in connection with an aluminum outer conductor at an exposed point separated from 16 will be circumvented. Thus, the ferrule 80 will at its ends not be terminated to the outer conductor 16 but will be spaced therefrom by the insulating material or gasket 35 and gasket 90. This would, of course, be the case if 16 were of copper and 34 were of a different metal or differently plated.
In an actual embodiment manufactured in accordance with the invention for use with the cable wherein the outer conductor was of 0.375 inch in diameter and 0.325 inch in thickness, and the dielectric material 18 was foamed polyethylene, the member 34 was made of beryllium copper material 0.014 inch in thickness and of an OD. equal to 0.319 inch. The cutting edge or bevel 38 was made with an angle A equal to 30 degrees.
This unit was found to satisfactorily terminate 75 ohm cable at signal frequencies of 10 to 216 megacycles.
Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.
What is claimed is: p
1. In a coaxial connection the combination including a coaxial cable having an inner conductor and an outer conductor coaxially disposed therearound with the space between said inner and outer conductors substantially filled with a solid dielectric material, the said outer conductor being formed of a rigid metallic tubing of a given and constant diameter along its length, a connector for said cable including an outer metallic body having at one end means thereon to facilitate mating with another connector and having at the other end a sleeve extension, a bore extending through said body and a dielectric insert fitted within said bore toward the said one end, a center contact fitted within said insert terminated to the center conductor of said cable with a portion thereof projecting forwardly toward said one end for contact engagement with the center contact of another connector, a ferrule member having an inner diameter approximately equal to the outer diameter of said outer conductor and fitted thereover with the said outer conductor positioned over said sleeve extension and the said ferrule member crimped inwardly terminating said outer conductor to said sleeve extension and to said connector with said dielectric material extending into said sleeve extension, the said sleeve extension having a relatively thin wall section and an outer diameter very slightly less than the said given inner diameter of the outer conductor and fitting tightly against the inner surface of the cable outer conductor and further having a sharp leading edge which separated the cable dielectric material from the cable outer conductor without expansion of said outer conductor during insertion in said cable, whereby assembly of said connector to said cable is facilitated with minimum damage to the dielectric material, minimum change in spacing between the inner and outer conductive paths formed within said sleeve extension and minimum required force in inserting said sleeve extension into said cable outer conductor.
2. The connection of claim 1 wherein the said sharp leading edge of said sleeve extension tapers inwardly from the end of said sleeve extension to guide the said dielectric material of said cable within the bore of said connector during insertion of said sleeve extension within said cable outer conductor.
3. In a coaxial connection a connector comprised of first and second outer metallic body members, each of said body members having a sleeve extension with a bore extending through the body member and each having at one end portions for intermating, each of said first and second body members including a dielectric insert in the bore at the one end with each dielectric insert supporting coaxially within each said member a center contact member, each center contact member including a portion at one end for intermating with the center contact member of the other body member, a coaxial cable terminated to each half, said cable including an inner conductor terminated to the center contact member and an outer conductor coaxially disposed therearound with the space between the cable inner and outer conductors being substantially filled with a solid dielectric material, the said outer conductor being formed of a rigid metallic tubing of a given constant inner diameter and a given constant outer diameter and terminated to the said extension with the said bore of each of said body members receiving the inner conductor of said cable inserted therethrough and receiving a portion of the dielectric material of said cable in unbroken length and in direct engagement with the inner surface of said sleeve extension, the said sleeve extension of each of said body members further having at the end thereof opposite to the said one end of said connector a sharp cutting edge of a maximum diameter only slightly less than the said given inner diameter of said outer conductor, said edge being joined by an inwardly tapering portion operable upon insertion of said extension into said cable in cleaving said dielectric material from the inner surface of said outer conductor and easing insertion of said extension within said cable with minimum insertion force and minimum damage to said dielectric material and means fitted over the said outer conductor of the cable in a position overlying the said sleeve extension of each of said body members to terminate the cable outer conductor to said sleeve extension for each of said body members.
4. The connection of claim 3 including a ferrule of thin wall section and malleable metal for each of said body members, said ferrule having an inner diameter before deformation only slightly larger than the outer diameter of said outer conductor permitting a sliding fit thereover with each said ferrule being crimped inwardly effecting the termination of said outer conductor to the sleeve extension of each of said body members.
5. In a coaxial connection, the combination comprising a coaxial cable including an inner conductor and an outer conductor of rigid metallic tubing coaxially disposed therearound with the space therebetween substantially filled with a dielectric medium, a coaxial connector comprised of an outer metallic body having at the forward end means to mate with a further connector and having therein a bore extending therethrough and a dielectric insert secured within said bore, a center contact member carried by said insert coaxially of said outer metallic sleeve and terminated to the inner conductor of said cable, the said outer body including at the other end a metallic extension of thin wall section inserted within said cable engaging the outer conductor thereof, a malleable ferrule positioned over said outer conductor and said extension and crimped inwardly terminating said outer conductor to said extension and to said connector, the said ferrule having at the end thereof opposite to the said one end of said connector an annular flange extending out radially around said one end and then axially along said outer conductor defining an annular recess between the inner surface of said llange and the outer surface of said outer conductor, a gasket fitted within said space having an inner diameter less than the outer diameter of said outer conductor and an outer diameter greater than the inner diameter of said flange in the axially extending portion thereof and compressed radially between the surfaces of said axially extending portion and said outer conductor to seal said connector and said cable as terminated thereto through the outer conductor thereof, a gasket receptacle of elastic material snapped over said flange and extending around the end of said ferrule, said receptacle including a portion extending radially inwardly to a diameter less than the average diameter of said gasket holding said gasket within said recess.
6. In a coaxial connection, the combination comprising a coaxial cable including an inner conductor and a rigid tubular outer conductor comprised of a given metallic material, a connector including an outer sleeve member having at one end means to interconnect to a mating connector and at the other end a sleeve extension of an outer diameter and configuration fitted within the outer conductor of said cable without deforming said outer conductor, a bore extending along said sleeve member and a dielectric insert fitted within said bore, said dielectric insert carrying a center contact member terminated to the inner conductor of said cable, a ferrule member positioned over the outer conductor of said cable and over said sleeve extension and crimped inwardly terminating said outer conductor to said sleeve extension and to said connector, the said ferrule member being of a metallic material different from the metallic material of said outer conductor,
the said ferrule member having the end thereof opposite References Cited to the said one end of said connector spaced outwardly UNITED STATES PATENTS in a radial sense away from and out of contact with the outer conductor of said cable and formed to define a 3,142,721 7/1964 f 174-89 X recess extending therearound, a gasket of insulating ma- 5 3,245,027 5/1966 zlegler 174 89 X terial compressed within said recess between said ferrule FOREIGN PATENTS member and said outer conductor and an insulating receptacle extending around the said end of said ferrule and 942143 11/1963 Great Bntam' afiixed to said ferrule member, the said insulating recep- I tacle including a portion extending inwardly trapping said 10 DARRELL CLAY Examine gasket within said recess. L. E. ASKIN, Examiner.