US3474532A - High voltage coaxial connector - Google Patents

Description

W. L. SCHUMACHER HIGH VOLTAGE COAXIAL CONNECTOR Oct. 28, 1969 3 Sheets-Sheet 1 Original Filed Oct i Mn H. M P m .NN v R gi A In i INVENTOR. AM Luupow SHDMAGH IR 0a. 28,1969 w. 1.. SCHUMACHER 3. 7

HIGH VOLTAGE COAXIAL CONNECTOR Original Filed Oct. 5, 1964 I 3 Sheets-Sheet a I N VEN TOR. WILLIAM LuoLow Scnumcuun United States Patent 3,474,532 HIGH VOLTAGE COAXIAL CONNECTOR William Ludlow Schurnacher, Camp Hill, Pa., assignor to AMP Incorporated, Harrisburg, Pa.

Original application Oct. 5, 1964, Ser. No. 401,546, now Patent No. 3,317,882, dated May 2, 1967. Divided and this application Mar. 7, 1967, Ser. No. 621,197

Int. Cl. H011 43/00; B23p 25/00 US. Cl. 29-628 4 Claims ABSTRACT OF THE DISCLOSURE This application is a division of application Ser. No. 401,546, filed Oct. 5, 1964, now Patent No. 3,317,882.

This invention relates to electrical connectors and more particularly to electrical connectors for use in a high voltage environment.

In high voltage applications, the conductor means carrying the high voltage has to be terminated at specific locations. These terminations have to be selected with care in order to preclude the occurrence of corona, since, if corona does occur, the efliciency of the high voltage application is diminished, and deterioration of the insulating medium at the terminations occurs.

It is, therefore, an object of the present invention to provide an improved electrical connector suitable for use with high voltages.

Another object of the present invention is to provide an electrical connector wherein the amount of air therein is reduced to a minimum.

An additional object of the present invention is to provide a high voltage electrical connector in which corona discharges do not occur.

A still further object of the present invention is to provide a high voltage electrical connector wherein termination of the center conductor is riveted in place.

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 is shown and described an illustrative embodiment of the invention; it is to be understood, however, that this embodiment is not intended to be exhaustive nor limiting of the invention but is given for purposes of illustration and 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 cross-sectional view of the high voltage electrical connector connected to a coaxial cable means;

FIGURE 2 is a partial sectional view of FIGURE 1 but on an enlarged scale;

FIGURE 3 is a partial sectional view but on an en larged scale of FIGURE 1;

FIGURE 4 illustrates a type of coaxial cable onto which the present invention is to be connected;

FIGURES 5-7 illustrate the steps by which the center conductor means of the cable means is connected to a center connector element; and

3,474,532 Patented Oct. 28, 1969 FIGURE 8 illustrates a mold to form one-half of the connector.

Turning now to the drawings and more particularly FIGURES 1-4, there is illustrated a high voltage connector C for connection onto a coaxial cable means CM. This coaxial cable means is a high voltage cable and is manufactured by the Boston Insulated Wire and Cable Company, Boston, Mass., and comprises an outer insulation 1 surrounding a conductive braid 2 which, in turn, surrounds a semi-conductive tape 3. A dielectric medium 4 is disposed between tape 3 and another semi-conductive tape 5 which, in turn, surrounds another conductive braid 6. A core 7 of insulation material is disposed within braid 6 and provides support therefor. Coaxial cable means CM is stripped in the manner set forth in FIGURE 1 so that the high voltage connector can be properly connected thereto.

High voltage connector C comprises two identical members 8 and 9 except that hollow metallic shell 10 includes a flange 12 at its large end while the large end of hollow metallic shell 11 includes thread 13. Another minor difference is that center connector element 14 in member 8 in which the center conductor is to be secured, has a female section 15 in which a male section 16 of similar center connector element 17 disposed in member 9 is to be disposed. Since members 8 and 9 are identical in construction, with the exception of the dififerences pointed out hereinabove, only one member will be described in detail.

Shell 10 is frusto-conical in configuration and has a flat section 18 near the small end thereof which extends parallel to the longitudinal axis. Flat section 18 merges into a tapered section 19 which terminates at the small end of shell 10. The inner surface of shell 10 is frusto-conical to a point almost opposite the junction between sections 18 and 19 whereupon it merges into a flat surface 21 coaxial with the axis of shell 10.

Insulating material 22, which is preferably made of silicone rubber, or the like, is disposed in shell 10, and, as can be perceived, the outer surface of insulating material 22 has a configuration consonant with that of inner surfaces 20 and 21 of shell 10'. A segment 23 of insulating material 22 extends outwardly beyond the small end of shell 10 and has a tapered surface 24 in alignment with the tapered surface of section 19 so that these tapered surfaces define a frusto-conical configuration. A bore 25 of the same diameter extends centrally through insulating material 22 and terminates at an abutting surface 26. Bore 25 is in communication with a frusto-conical opening 27 disposed in the large diameter end of insulating material 22. Entrance 28' of frusto-conical opening 27 is circular until it merges with frusto-conical opening 27, as seen in FIGURES 5-7. The surface of insulating material 22 between entrance 28 and the edge of the large diameter section of shell 10 is serrated defining spaced circular sections 29, 30 and 31. Sections 29 and 30 extend outwardly beyond the edge of shell 10 while section 31 is in alignment therewith. Part 32 of insulating material 22 also extends outwardly from the edge of shell 10. It is to be noted that section 29 extends outwardly further than that of section 30, and, of course, section 30 extends outwardly further than section 31 from the edge of shell 10.

Insulating material 22' of member 9 includes sections 29 and 30' similar to circular sections 29 and 30 of insulating material 22 in member 8 but that section 31 extends outwardly from the edge of shell 11 further than corresponding section 31. Thus, the distance measured along circular sections 29 through 31 of insulating material 22 and circular sections 29 through 31' of insulating material 22' defines a path which is over 10 inches in length.

Center connector element 14 defines a frusto-conical configuration from female section 15 to the end thereof. A bore 33 of constant diameter extends centrally through center connector element 14 and is in communication with stepped-down sections 34 and 35, which, in turn, are in communication with the interior of female section 15. Entrances 36 and 37 of respective sections 35 and 15 are preferably beveled (see FIGURES 5-7).

Shells and 11, insulating material 22 and 22' and center connector elements 14 and 17 are assembled to form unitary structures. This is accomplished by securing center connector elements 14 and 17 and shells 10 and 11 to respective mold parts MP (see FIGURE 8) having a configuration corresponding to that of circular sections 2931 and 29'-31 by means of mandrels M which form bores 25 and 25. Another mold part MPa is secured to shells 10 and 11 at their smaller end via the mandrels, and these mold parts MPa form segments 23 and 23'. The inner surface of shells 10 and 11 and the outer surface of elements 14 and 17 are preferably coated with a suitable bonding material while the mandrels are coated with a suitable release agent. Insulating material 22 and 22' is then introduced within shells 10 and 11 through one of the mold parts to form the desired configuration of the insulating material in accordance with that disclosed. After the insulating material has filled the void within shells 10 and 11, the insulating material is placed under vacuum in order to remove all air pockets and render it free of air as well as to remove all air from the interfaces between the shells and the insulating material and the center connector elements and the insulating material. When the insulating material has set, the mold parts and mandrels are removed from shells 10 and 11 which are now unitary structures.

Of course, it is possible to mold insulating material 22 and 22 in its desired form and then insert this material within respective shells 10 and 11 with elements 14 and 17 being inserted in their proper places in the presence of bonding material on the shells and the elements to form the shell unitary structures.

In assembly, coaxial cable means CM is properly stripped in the manner illustrated in FIGURES l and 2. If dielectric material 4 is of the wrapped variety, it is preferable to wrap the stripped end thereof with a nylon monofilament or the like in order to preclude any air gaps occurring therein. Grease is also applied to the forward portion of dielectric 4 to eliminate any air gap made possible by mismatch of dielectric 4 and abutting surface 26 of insulating material 22. The assembly of shell 10, insulating material 22 and center connector element 14 is pushed onto the coaxial cable means such that elements 4 through 7 pass into bore 25 of insulating ma terial 22 and the tapered surfaces of sections 23 and 19 of insulating material 22, and shell 10 fits underneath semi-conductive tape 3 and braid 2, as shown in FIGURE 3, with tape 3 terminating about halfway along the tapered surface of section 19. The stripped end of dielectric 4 engages surface 26 and braid 6 and core 7 extend into bore 33 with the end of braid 6 extending beyond entrance 36 while the end of core 7 terminates about midway of bore 33, as illustrated in FIGURES 2 and 5 through 7. As stated hereinbefore, the grease applied to the stripped end of dielectric 4 is disposed between surface 26 and the stripped end of dielectric 4 in order to compensate for any mismatch therebetween, to exclude any air therefrom, and to form a seal therebetween. This grease is preferably of the monoflow type identified as Nebula EP2, which is manufactured by the Standard Oil Company of New Jersey.

As shown in FIGURE 6, the inner sharp edge of center connector element 14 extends within semi-conductive tape 5 and dielectric 4 so that semi-conductive tape 5 is in engagement With the outer surface of center conductor element 14.

A Pop rivet assembly 38 of the type manufactured by United Shoe Machinery Corporation, Shelton, Connecticut, comprises a tubular member 39 having at one end an outwardly-directed flange 40 and an inwardlydirected flange 41 at the other end. Shank 42 of a pin 43 is disposed within tubular member 39 and extends outwardly from flange 40. Pin 43 includes a head 44 disposed adjacent flange 41, and area 45 between shank 42 and head 44 is of less diameter than that of shank 42.

Pop rivet assembly 38 is inserted within braid 6, stepped sections 34 and and into bore 33 of center connector element 14, as illustrated in FIGURE 6. \Vith the Pop rivet assembly in position within center connector element 14, a conventional Pop rivet actuating tool (not shown) is placed into engagement with the part of shank 42 extending outwardly from flange 40. Upon actuation of the Pop rivet actuating tool, end 43 moves relative to center connector element 14 causing head 44 to move completely within tubular member 39 and coming to a wedged position of rest therein within stepped section 35, as illustrated in FIGURE 7.

The action of head 44 moving within tubular member 39 causes flange to be seated within beveled entrance 36, moves the part of tubular member 39 disposed in bore 33 outwardly against braid 6 disposed in bore 33 thereby spreading braid 6 against bore 33 and the interface between bore 33 and stepped section 34, and, at the same time, shortening the length of tubular member 39. The continued movement of head 44 within stepped section 34 moves the tubular member, in this section, outwardly against braid 6 causing the braid to be wedged against stepped section 34 effecting excellent electrical and 'meachanical contact. At the interface between stepped sections 34 and 35, head 44 then comes to rest with parts disposed in stepped sections 34 and 35, and, in doing so, moves the part of tubular section 39 therein outwardly against braid 6 causing the braid to be wedged against stepped section 35. After head 44 has moved to its position of rest at stepped sections 34 and 35, as illustrated in FIGURE 7, shank 42 is removed from head 44 by additional tensile force which causes shank 42 to break at area so that shank 42 does not remain a part of the Pop rivet assembly after the Pop rivet has been secured in position. The wedging action of tubular member 39 against braid 6 becomes progressively increased from bore 33 to stepped section 35 whereat it reaches its maximum wedging action. The wedging action of flange 40 against braid 6 at entrance 36 is also excellent. Thus, as can be discerned, there has been disclosed a unique connection of the center braid 6 onto center connector element 14 by a rivet means to provide an excellent electrical and mechanical connection external of the critical high voltage field where sharp projections or air of any amount cannot be tolerated.

Now that braid 6 has been effectively connected to center connector element 14, braid 2 and tape 3 are aflixed in intimate contact with the tapered surfaces of sections 19 and 23. A suitable insulating material 47, such as, insulating tape is wrapped tightly over braid 2 and semi-conductive tape 3 so as to exclude any air pockets. Clamp 46 of any desirable form is used to aflix braid 2 to flat section 18 of metallic shell 10, thus, providing a positive electrical connection as well as providing mechanical strength. Additional wrapping of insulating tape 47 is used to cover the clamp and braid ends. If desired, a conductive paint or grease may be spread on the surface of cable dielectric medium 4 and surface 24 to aid the exclusion of air during this final assembly operation. Also, if desirable, insulating material 47 may be accomplished in any desirable fashion such as, slipping a premolded boot having a contoured inner surface so as to provide air exclusion from between the surfaces of 4 and 24 and tape 3. The same procedure, as outlined hereinbefore, is followed in connecting the coaxial cable means to the elements of member 9.

After the coaxial cable means has been connected to the elements of members 8 and 9 of the connector member, members 8 and 9 are ready to be brought into engagement to interconnect shell 10 with shell 11 and center connector element 14 with center connector element 17. After members 8 and 9 have been brought into engagement, circular sections 29 through 31 of insulating material 22 mesh with circular sections 29' through 31' of insulating material 22 and male section 16 of center connector element 17 is disposed within female section 15 of center connector element 14. Beveled entrance 37 of female section 15 and semi-circular segmented spring lip 48 on male section 16 facilitate the insertion of male section 16 within female section 15. The diameter of semi-circular spring lip 48 is slightly larger than that of the interior surface of female section 15 so that an excellent mechanical and electrical connection is obtained between center connector element 14 and center connector element 17.

In order to draw the edges of members 8 and 9 into a tightly abutting relationship, as illustrated in FIGURES 1 and 2, a threaded coupling member 49 engages flange 12 of shell 10 and threaded section 13 of shell 11, and, upon tightening coupling member 49 onto threaded section 13, members 8 and 9 are brought into tight engagement. At this position of engagement, circular sections 29 through 31 are tightly meshed with circular sections 29' through 31, which excludes all air therefrom and male section 16 is properly seated within female section 15. Thus, the path from engaged shells 10 and 11 to engaged center connector elements 14 and 17 is along tightly meshed circular sections 29 through 31 and 29' through 31, and is over 10 inches in length, as mentioned hereinbefore. As can be perceived, the points of change in the direction of the path are not in alignment so that these points which are parallel with the voltage stress between center connector elements 14 and 17 and outer shells 10 and 11 will not have any cumulative effect. The points of circular sections 29 and 29 have been arranged to be the furthest from the center line of the connector in order to place them at a point of lower voltage stress in the field because the highest voltage stress occurs at the surface of inner tape 5 and center connector elements 14 and 17.

The electrical connection between male section 16 and female section 15 of the center connector elements is made interiorly of the electrical field so that the space therebetween which contains air does not effect this connection. Semi-conductive tapes 3 and 5, disposed on each side of dielectric medium 4, obviate the occurrence of any air between braids 2 and 6, since they are in intimate contact With this dielectric medium. Dielectric medium 4 fits snugly within insulating material 22 so that no air is present within the connector. If the surface of dielectric medium 4 is not smooth, a grease is used to fill any possible voids.

As can be discerned, there has been disclosed a novel coaxial cable connector for connection on coaxial cable means carrying high voltage and including a unique connection for the center conductor means.

It will, therefore, be appreciated that the aforementioned and other desirable objects have been achieved; however, it should be emphasized that the particular embodiment of the invention, which is shown and described herein, is intended as merely illustrative and not as restrictive of the invention.

What is claimed is:

1. A method of connecting a coaxial connector onto a coaxial cable means having inner and outer conductor means separated by dielectric means, said method comprising the steps of stripping said coaxial cable means to expose said inner and outer conductor means and dielectric means, placing a metallic shell member having insulation means and center connector means therein over said dielectric means and inner conductor means and under said outer conductor means with said inner conductor means extending along an opening in said center connector means, securing said outer conductor means to said shell member, and riveting said inner conductor means Within said opening of said center connector means.

2. A method according to claim 1 Which includes the further step of applying insulation over said outer conductor means, part of said shell member and onto outer insulation of said coaxial cable means.

3. A method of connecting a hollow conductor member of a coaxial cable to an opening in an electrical connector member comprising the steps of placing a section of said hollow conductor member in said opening of said connector member, positioning a conductorsecuring member within said section of said hollow conductor member inside said opening, and forcefully moving an expanding member along an interior surface of said conductor-securing member thereby expanding at least a portion of said conductor-securing member against said section of said conductor member and said opening and thereby wedging said section of said conductor member between said opening and said securing member to provide a mechanical and electrical connection between said conductor member and connector member.

4. A method of connecting a hollow conductor member of a coaxial cable to an opening having stepped areas in an electrical connector member comprising the steps of placing a section of said conductor member within said opening of said connector member, positioning a hollow conductor-engaging member within said section of said conductor member within said stepped opening, and forcefully moving an expanding member along said conductor-engaging member thereby expanding the size of at least a portion of said conductor-engaging member against said stepped areas and securely wedging said section of said conductor member within said stepped opening therebetween to provide a mechanical and electrical connection between the conductor member and connector member.

References Cited UNITED STATES PATENTS 2,163,783 6/1939 Fisher 29-4528 XR 2,635,501 4/1953 Eichner 72 2,768,105 10/ 1956 Dittmore et al 29-628 3,071,399 1/1963 Cronin 29-522 3,120,702 2/1964 Smith 29--527 3,130,478 4/ 1964 Stevens 29628 3,332,813 7/1967 Clarke 29527 XR FOREIGN PATENTS 904,827 8/ 1962 Great Britain.

JOHN F. CAMPBELL, Primary Examiner R. B. LAZARUS, Assistant Examiner US. Cl. X.R. 29-461, 522, 527

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