US3474377A

US3474377A - Electrical connector device having improved grounding means for shell

Info

Publication number: US3474377A
Application number: US597929A
Authority: US
Inventors: Ernest R Carlson; Vincent F Lipinski
Original assignee: Harvey Hubbell Inc
Current assignee: Harvey Hubbell Inc
Priority date: 1966-11-30
Filing date: 1966-11-30
Publication date: 1969-10-21
Anticipated expiration: 1986-10-21

Description

Oct. 2, l969 E. R. CARLSON ETAL 3,474,377

ELECTRICAL CONNECTOR DEVICE HAVING IMPROVED GROUNDING MEANS FOR SHELL Filed NOV. 5o, 196e 3,474,377 ELECTRICAL CONNECTOR DEVICE HAVING IMPROVED GROUNDING MEANS FOR SHELL Ernest R. Carlson, Fairfield, and Vincent F. Lipinski,

Stratford, Conn., assignors to Harvey Hubbell,

incorporated, Bridgeport, Conn., a corporation of Connecticut Filed Nov. 30, 1966, Ser. No. 597,929 Int. Cl. H011' 3/06, .T3/58, 15/06 U.S. Cl. 339-14 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an electrical connector device having improved grounding means, and more particularly to an electrical connector device having a metallic protective shell and improved grounding means therefor, including improved means to secure a grounding wire directly to the shell.

To satisfy rigorous safety requirements, it is often necessary to ground the usual exposed metal shells of electrical yconnector devices. Grounding of the metal shells is achieved either by connecting the outer metal shells of the connector body and cap directly in a separate ground circuit, thereby completing the ground circuit through the shells, or by providing a grounding shunt or path through the metal shells extending from and being parallel to the usual internal equipment ground circuit of the electrical connectors, which passes through the usual ground contacts and terminals thereof.

A known arrangement for grounding the exposed metal shells by connecting them directly in a separate ground circuit comprises securing the ground wires to a ground wire binding screw anchored directly in the metal shell. This arrangement is limited to utilization with relatively small grounding wires. A Well known prior art shell grounding shunt includes securing one end of a flexible metal conductor strip to an internal ground wire terminal, as by riveting or welding thereto, and forming the other end so that it is biased into rubbing contact with the interior of the shell. It will be readily understood by those skilled in the art that this shunt construction requires current iiow to pass through at least two joints, one riveted or welded and the other one of rubbing contact. One known prior art shunting arrangement eliminates one joint by capturing one end of a flexible metal conductor strip in a clamp type equipment ground terminal while maintaining the other end biased in rubbing contact with the interior of the shell in the usual manner. In this arrangement, the ground wire is placed in direct contact with the ground shunt conductor strip and current flow must only pass through one joint, namely, the rubbing contact joint at the interior of the metal shell.

The grounding means of each of the above arrangements is objectionable because heating occurs Wherever the current iiow encounters resistance, for example, in the vicinity of the riveted joints and the rubbing contact joints. This objectionable heat rise occurs particularly under full load conditions. Furthermore, it has been found in practice that this localized heat build-up causes the riveted joints eventually to loosen and the springnited States Patent loaded shunt conductor strip of the rubbing contact joint to lose contact pressure or continuity due to corrosion. Thus, it is readily apparent that a minimum of joints in the grounding path is desirable.

Accordingly, it is the primary object of this invention to provide an improved electrical connector device having an improved shell grounding means that eliminates a ground terminal within the usual molded terminal section of the electrical connector device, and a rubbing shunt joint for grounding the metal shell by providing means for securing a relatively large ground wire directly to the metal shell.

A further object of the invention is to provide an improved shell grounding means in an electrical connector which minimizes the heat rise and voltage drop in the shell grounding circuit by eliminating all unnecessary joints and all spring biased joints in the grounding path by providing a ground wire of maximum size secured directly to the metal shell.

A still further object of the invention is to provide an improved grounding means for an electrical connector device wherein the grounding circuit elements are spaced from all current carrying elements and having a neat appearing ground wire clamp mounted directly on the exterior of the metal shell.

These objects are achieved in one form by providing an electrical connector device having improved grounding means for grounding the metal shell which comprises: electrical contact-terminal elements mounted on an insulating body member and arranged to receive leads of the conductive wires of an electrical supply cable; a metal shell within which the insulating body member is disposed; and shell grounding means arranged to clamp the ground wire of the electrical supply cable directly to the metal shell. The grounding means includes a clamping member arranged to be secured to the exterior of the metal shell and an inwardly extending arcuate portion of the shell which cooperates with the clamping member to clamp the ground wire therebetween.

Other objects and further details of that which we believe to be novel and our invention will be clear from the following description and claims taken with the accompanying drawing, wherein:

FIG. 1 is a side elevational view of an electrical connector cap and body in accordance with the present invention with portions broken away to show the shell grounding means;

FIG. 2 is a sectional view of an electrical connector device taken substantially on line 2 2 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken substantially along line 3 3 of FIG. 2 showing a grounding wire secured in place by the clampling member;

FIG. 4 is a fragmentary end elevational view of the metal shell and clamping member of the FIGS. 1-3 dev1ce;

FIG. 5 is a fragmentary side elevational view showing the clamping member mounted on the metal shell; and

FIG. 6 is a perspective view of the clamping member constructed in accordance with the present invention.

With particular reference to FIG. 1 there is illustrated a connector body 1 and a connector cap 2, each of which is provided with an outer protective cover, a protective metal shell and improved shell grounding means including an overlapping clamping member 22. The ground circuit is completed through a grounding wire of the electrical cables C and through the metal shells 10, which are in electrical contact through the usual spring contact strip 11. The shells 10 are surrounded by outer protective covers P.

The structural elements to be described, which relate to the invention, are identical in their application to both the connector cap and the connector body and, therefore,

the specification shall hereinafter refer to an electrical connector device and the structure described shall apply equally to both types of electrical connector device.

With reference to FIGS. 2-6, there is illustrated a fivewire electrical connector device constructed in accordance with this invention. The device comprises a usual cup-shaped metal shell disposed in an outer cupshaped protective cover P, which may be made of a strong durable plastic material, support a cable strain relief clamp S at one end, and compress a resilient sealing cushion ring R between it and the closed end of the shell 10. A first body portion 12 made of a rigid electrical insulation material and cup shaped is located within the shell 10, and a second body portion 14 of similar material is located within the shell but spaced from the end of the shell by the first body portion 12, through which the lead wires of an electrical supply cable C extend into the wiring area 15 formed therebetween. The second body portion 14 is massive and recessed, and carries the usual clamp-type terminals 16 which are arranged to receive the electrically conductive power wires 18 of the electrical supply cable C. As can be seen in FIG. 3, the illustrated device includes four electrically conductive power wires 18 each connected to one of the clamp-type terminals 16, and a separate grounding wire 20 connected directly to a source of ground and to the shell 10 by the overlapping clamping member 22 which is secured to the shell by means of the mounting screws 24.

The metal shell 10 comprises a substantially cylindrical wall 26 which is open at one end and has a radially inwardly extending flange 28 at its other end which defines a rear wall having a central aperture 29. A cut-out 30 is formed through the flange 28 and the adjacent portion of the cylindrical wall 26, and is located centrally of a radially inwardly offset wall portion 32. The portion 32 is concentric with the cylindrical wall 26, but has a smaller radius of curvature so as to allow the overlapping clamping member 22 to be seated flush with the outer surface of the cylindrical wall 26. Located centrally of the portion 32 immediately adjacent the cut-out 30 is a sheared radially `inwardly extending arcuate wire clamp portion 34 which is arranged to coact with the overlapping clamping member 22 to secure a ground wire 20 therebetween. Tapped holes 36 are located on each side of the sheared portion 34 and arranged to threadedly receive the mounting screws 24 which secure the overlapping clamping member 22 to the shell 10.

The clamping member 22 comprises a formed metal plate including an arcuate main wall 38, having the same radius of curvature as the cylindrical wall portion 26 of the metal shell, and a substantially normal wall 40 which acts to close the cut-out portion in the flange 28 when the clamping member is secured in place and further acts as a snubbing strain relief for the ground wire 20. Extending laterally outwardly from and described on the same arc as the main wall 38 are opposed lateral mounting arms 42 having screw receiving ways 44. Ways 44 are slightly larger than the diameter of the shanks of the mounting screws 24 and enable the overlapping clamping member 22 to rest on the shanks of the mounting screws 24 and to be firmly clamped in place by the force of the screw heads when it is desired to secure the clamping member 22 to the shell 10. Disposed in the main wall 38 are inwardly extending indentations 46 which coact with the sheared arcuate cable clamp portion 34 to lockingly secure the ground wire 20 in place against inadvertent removal when the overlapping clamping member 22 is mounted in place.

The first body portion 12 is constructed so that it can be readily accepted in the metal shell 10. This Iis accomplished by molding an inwardly offset walled seat 48 arranged to receive the offset portion 32 of the metal shell. A cut-out 50 similar to the cut-out 30 in shell 10, is located in the seat 48, and allows the ground wire 2.0 to be positioned in place. When positioned in the shell 10, the first body portion is disposed, as shown in FIG. 2, to have the seat 48 inwardly surround clamp portion 34 of the shell 10.

To assemble and Wire the connector body 1, the electrically conductive wires 18 are connected to the clamptype terminals 16 in the usual manner, and the

body portions

12 and 14 are secured in the metal shell 10. The ground wire 20, is isolated from the conductive wires 18 and moved from the wiring area 1S through the cut-

outs

50 and 30, and is positioned adjacent the exterior surface of the sheared arcuate cable clamp portion 34. Once the ground wire 20 is so positioned, the overlapping clamping member 22 is slid axially relative to shell 10 and rested upon the shanks of the mounting scerws 24. Finally, the screws are tightened and the overlapping clamping member 22 is urged toward the shell 10, thereby securely clamping the ground wire 20 in place between the portion 34 and member 22, and insuring that the wire 20 will not be inadvertently displaced, by driving the inwardly extending indentations 46 into the wire to effect a lock.

The connector cap 2 is wired and assembled in a generally similar manner. The grounding path is continued from the connector body 1 to the connector cap 2 by means of the usual spring contact strip 11, located in the usual outwardly deformed skirt portion 52 of the metal shell of the connector body which is biased against the outer surface of the shell of the connector cap.

Having described the improved grounding means for connector device shells, it will be readily appreciated by those skilled in the art that the secure clamping of the grounding wire 20 affords a highly desirable direct grounding of the metal shell by a separate ground path, with all its attendant advantages. Further, the ground wire clamping means formed by shell clamp portion 34 and the arcuate wall 38 is configured to accommodate a variety of large diameter ground wires. Thus, it is apparent that not only has the prior existing deficiency of grounding the metal shells by means of spring biased grounding shunts been eliminated, but that the improved grounding means does not require any grounding terminals, and thereby frees one of the clamp-type terminals 16, previously used as a ground wire terminal, for use by another electrically conductive power wire 18. In the improved grounding means, the equipment ground path includes the shell grounding path.

It should be understood that the present disclosure has been made only by way of example and that numerous changes in details of construction and the combination and arrangement of parts may be resorted to without departing from the true spirit and the scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electrical connector device having improved grounding means comprising: a metal shell including a substantially cylindrical wall, and a normal end wall at one end thereof having a central aperture therein; an insulator body member disposed within said metal shell; electrical contact elements having electrical terminal means carried by said body member; said terminal means arranged to secure a plurality of current-carrying wires; and clamping means including a clamping member secured to and arranged to clamp a ground wire directly to said metal shell; wherein said clamping member is substantially L-shaped for engagement with the exterior of said metal shell including a main wall portion of said clamping member for lying adjacent said cylindrical wall for clamping the ground wire between said main wall and said cylindrical wall, and a wall portion disposed substantially normal to said main wall for acting as a strain reliever for the ground wire.

2. The improved electrical connector device defined in claim 1 wherein said main wall is arcuate and has a curvature substantially conforming to the curvature of said cylindrical metal shell for lying adjacent thereto.

3. The improved electrical connector device defined in claim 2 wherein said clamping member includes inwardly extending indentations disposed in said main wall portion for lockingly securing the ground wire in place between said cylindrical wall and said clamping member.

4. The improved electrical connector device defined in claim 2 wherein: said clamping member further includes laterally oppositely extending arms projecting from said main wall portion which conform to the curvature of said main wall portion; and said clamping means further includes mounting means cooperating with said arms for securing said clamping member to said metal shell.

5. An electrical connector device having improved grounding means comprising: a metal shell including a substantially cylindrical wall, and a normal end wall at one end thereof having a central aperture therein; an insulator body member disposed within said metal shell; electrical contact elements having electrical terminal means carried by said body member; said terminal means arranged to secure a plurality of current-carrying wires; and clamping means including a clamping member secured to and arranged to clamp a ground wire directly to said metal shell; wherein said metal shell includes an offset portion defining a wall portion of smaller concentric curvature relative to said cylindrical wall wherein said clamping member may be seated and, further, includes a radially inwardly extending arcuate portion disposed within said offset wall portion arranged to accommodate the ground wire, so that the ground wire may be clamped between said arcuate portion and said clamping member.

6. The improved electrical connector device defined in claim 5 wherein a cut-out portion is provided in said offset wall portion of said metal shell, adjacent said arcuate portion, and further extends into said normal end wall from said offset wall portion to said central aperture, for allowing the ground wire to be disposed between said arcuate portion and said clamping member.

7. The improved electrical connector device defined in claim 6 wherein an insulating spacer is provided with a cut-out, and an offset seat arranged to receive said offset portion of said metal shell, said cut-out being disposed adjacent said cut-out in said shell when the parts are assembled.

8. An electrical connector device having improved grounding means comprising: a metal shell including a substantially cylindrical wall, and a normal end wall at one end thereof having a central aperture therein; an

insulator body member disposed within said metal shell; electrical contact elements having electrical terminal means carried by said body member; said terminal means arranged to secure a plurality of current-carrying wires; and clamping means including a clamping member secured to and arranged to clamp a ground wire directly to said ,metal shell; wherein: said metal shell is provided with an inwardly offset wall portion defining a smaller concentric curvature than that of said cylindrical wall, an inwardly extending arcuate portion is disposed within said offset wall portion, and a cut-out is located adjacent said arcuate portion and further extends into said normal end wall from said offset wall portion to said central aperture; said clamping means comprises a substantially L-shaped clamping member including an arcuate main wall portion having .a curvature substantially conforming to the curvature of said cylindrical wall for being seated adjacent said inwardly offset wall portion and being substantially flush with the outer diameter of said cylindrical wall, laterally oppositely extending arms projecting from said main wall portion which conform to the curvature of said main wall portion, inwardly extending indentations disposed in said main wall portion for lockingly securing the ground wire in place between said inwardly extending arcuate portion .and said arcuate main wall portion, and a substantially normal wall portion at one end of said arcuate main wall portion acting as a snubbing strain relief for the ground wire; and said clamping means further includes mounting means cooperating with said arms for securing said clamping member to said metal shell.

References Cited UNITED STATES PATENTS 2,032,501 3/1936 Reynolds 339-14 2,410,618 11/1946 ZelOv 339-14 3,122,604 2/1964 COOk et al 174-51 FOREIGN PATENTS 207,092 11/ 1923 Great Britain. 611,474 10/ 1948 Great Britain.

MARVIN A. CHAMPION, Primary Examiner P. A. CLIFFORD, Assistant Examiner U.S. Cl. X.R. 339-