Abstract:
The electrical bonding block with grounding lug includes a ground wire clamping chock which bears against the ground wire, clamping the ground wire between the chock and the ground wire passage. A ground wire clamp screw engages the chock to pull the chock tightly against the ground wire. This mechanism avoids direct point contact by the contact screw with the ground wire, thereby precluding the formation of nicks and stress risers in the ground wire and subsequent stress corrosion and/or fatigue failure of the ground wire. The device may be adapted to connect virtually any type of electrical conductors having separate ground elements, but is particularly well suited as a bonding block and ground lug for connecting two lengths of coaxial cable.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to electrical connectors and the like. More specifically, the present invention relates to an electrical bonding block with a grounding lug for grounding the shielding or other ground of an electrical conductor, e.g., coaxial cable. 
     2. Description of the Related Art 
     A number of specialized electrical conductors have been developed in the past, with the various conductors serving various purposes and functions. One type of conductor commonly used for the conduction of relatively high frequency signals (e.g., television and very high frequency radio signals) is the shielded coaxial cable. Such cables essentially include a centrally located relatively thin center conductor enclosed in a relatively thick insulating material, with the insulator in turn being shielded by an electrically conductive shield to prevent interference with any electrical signal being conducted by the conductor. Such cables are commonly installed for household television systems, whether using satellite, cable, or broadcast antenna reception. 
     Such cable installations universally require connections at various points, such as at the entrance through the wall of the structure. Opposed externally threaded (male) connectors are universally used to connect the two ends of the exterior and interior coaxial cables at this point, with the cable ends generally including captured internally threaded connector nuts or fittings, or sometimes a slip-on attachment over the male threaded connectors. However, some means is also required for grounding the coaxial cable connection. Accordingly, various electrical bonding blocks, as they are known, have been developed, which serve as the connector for two lengths of coaxial cable and which also include some means for connecting the block to an electrical ground. 
     Quite typically coaxial cables are used to carry an RF signal from an antenna or external cable TV or telephony installation to a radio or television receiver or to a telephone. The center conductor usually carries the signal, and the shield is usually at circuit ground potential. Coaxial cable connectors include a tubular center pin to which the cable center conductor is attached, e.g., by soldering, and the shield is typically clamped to an external shell that encloses insulation surrounding the center pin. 
     While this arrangement is adequate for carrying the typical low voltage-low current RF signals received at an antenna, typically it is necessary to protect the installation from transient high voltage-high current incidents, such as lightning strikes. Without some form of protection, the transient voltages and currents may be carried by the coaxial cable, with resulting damage to television and radio receivers and other electronic equipment connected to the household wiring, and may potentially start fires by overloading and melting the coaxial cable or household wiring. Consequently, an external ground wire is clamped to the antenna mast and routed to a ground rod or other earth ground, such as metal plumbing pipes. An electrical bonding block is typically mounted to the building or other structure, and has a coaxial cable connector to connect coaxial cables in series, and a clamp to secure the external ground wire, which may be solid wire or stranded wire, and may be copper wire, aluminum wire, or the like. The shield of the coaxial cable is connected to the ground wire through the bonding block. Grounding the coax shield is often supplemented by using a lightning arrestor in the coax line between the antenna and the receiver or other electronic equipment. 
     Typically, such conventional electrical bonding blocks have a ground wire passage with a screw or bolt installed radially to the ground wire passage. The screw or bolt is tightened directly against the ground wire inserted in the passage, to form an electrical connection to ground. The problem with such direct engagement is that the relatively small “point” area of contact of the tip of the grounding screw with the ground wire causes the ground wire to deform at that point, and nearly always induces a “stress riser” in the wire, which weakens the wire at that point. This is particularly true where relatively soft metal (e.g., copper or aluminum) is used for the ground wire. Slight movement of the wire relative to the grounding lug will always occur over time, with such movement working the wire about the sharp engagement of the ground screw therewith and the stress riser. This eventually work hardens the ground wire, making it brittle, and weakens the ground wire sufficiently that it breaks. Even before breakage, stress corrosion often occurs in the stress riser formed in the ground wire, which increases the electrical resistance of the connection well beyond desired limits. 
     A few electrical grounding devices have been developed in the past that avoid the direct contact of the tip of a screw or bolt with the ground wire. An example of such a device is found in Japanese Patent Publication No. 64-2263, published on Jan. 6, 1989. This device uses a rectangular washer with downwardly folded corners, which engage the ground wire(s). A central screw tightens the washer against the ground wire(s). The result is similar to that described above with conventional screw type ground wire clamps, i.e., a relatively sharp point contact (in this case, the sharp edge or corner of the washer) engages the ground wire and likely nicks the wire to create a stress riser. 
     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, an electrical bonding block with grounding lug solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The electrical bonding block with grounding lug includes a connector for connecting two otherwise separate electrical conductors and further electrically bonding their ground or shielding elements to an electrical ground integral with the electrical conductor connecting means. The electrical ground connection comprises a ground wire passage through a grounding lug portion of the device, with a ground wire clamp screw axially offset from the ground wire passage. The screw engages a ground wire clamp chock and pulls the chock against a ground wire inserted in the passage, clamping the ground wire between the chock and the passage walls. 
     Numerous embodiments of the electrical bonding block are provided for herein. The connector for the connection of electrical conductors may comprise opposed identical male threaded coaxial connectors, or connectors for other types of electrically grounded conductors. The connectors may be directly opposed to one another, or may be installed at right angles (or other non-linear relationship) to one another. The ground wire passage may be parallel to the axis of one or both of the electrical conductor connectors, or may be at a right angle (or other angle) thereto. The ground wire clamp chock may comprise a straight, flat, beveled surface, or may include a concave form more closely conforming to the curvature of the wire. The ground wire passage may include a generally semicircular side opposite the chock, which extends completely across or through the ground wire passage to provide a greater surface contact area for the ground wire. The ground wire clamp screw may be cantilevered through the upper portion of the grounding lug, or may have its distal end captured within a support passage. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an enlarged perspective view of an electrical bonding block with grounding lug according to the present invention, showing its general configuration. 
         FIG. 2  is an enlarged side elevation view in section of the electrical bonding block of  FIG. 1 , showing various internal details of the grounding lug. 
         FIG. 3  is an enlarged side elevation view in section of an alternative embodiment of an electrical bonding block with grounding lug according to the present invention, showing an alternative configuration for the internal structure of the grounding lug portion. 
         FIG. 4  is a perspective view of another alternative embodiment of an electrical bonding block with grounding lug according to the present invention, wherein the electrical conductor connectors are normal to one another and the ground wire passage is normal to the base of the device. 
         FIG. 5  is a perspective view of another alternative embodiment of an electrical bonding block with grounding lug according to the present invention, wherein the ground lug portion is generally coplanar with the electrical conductor connectors. 
         FIG. 6  is a prior art perspective view of a conventional electrical bonding block, showing the conventional ground wire clamp screw, which is axially coplanar with the ground wire passage, directly engaging a ground wire installed in the passage. 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention comprises various embodiments of an electrical bonding block with a grounding lug, adapted for mechanically and electrically connecting two electrical conductors and electrically grounding the ground members thereof. While the electrical bonding block may be adapted for the connection and grounding of virtually any type of electrical conductor, it is particularly well suited for use in connecting and grounding coaxial cable conductors. 
       FIGS. 1 and 2  illustrate a first embodiment of the present electrical bonding block  110 . The bonding block  110  includes a body  112  comprising a cylindrical barrel housing an insulator of polyethylene, polyvinyl chloride (PVC), ceramic or the like that encircles coaxial cable center contacts, the body  112  having first and second electrical conductor connection terminals, respectively  114  and  116 , disposed thereon. In the example of  FIGS. 1 and 2 , the terminals  114  and  116  comprise mutually opposed externally threaded coaxial cable connectors, e.g., an F-81 coaxial cable coupler, but other electrical connector or terminal configurations may be incorporated into the bonding block  110  in accordance with the type of electrical conductors to be connected by the bonding block. The external threads of the connectors or terminals  114  and  116  are electrically grounded to the bonding block body  112  and provide for the grounding of the ground sheath, which conventionally surrounds the central conductor of coaxial cables, and which attaches to the externally threaded connectors  114 ,  116 . 
     An electrical grounding lug  118  extends from the bonding block body  112 , with the lug  118  providing for the mechanical and electrical connection of a ground wire G to the bonding block body  112 . The grounding lug portion  118  joins both physically and electrically with the bonding block body portion  112 , serving to conduct any ground current from the terminals  114 ,  116  through the body portion  112  and ground lug  118  to the ground wire G. The grounding lug  118  includes a hollow interior volume  120  therein, as shown in  FIG. 2  of the drawings. A ground wire passage  122  is formed transversely through each of the opposite walls  124  of the ground lug portion  118  to pass through the ground lug, with the ground wire G being inserted into the ground wire passage  122  to ground the device  110 . 
     A ground wire clamp screw passage  126  is formed through the intermediate wall  128  of the ground lug  118 , i.e., the wall extending between the two opposed walls  124  with their ground wire passage  122 . The clamp screw passage  126  is unthreaded, and its axis is laterally offset from the plane of the ground wire passage  122 . A ground wire clamp screw  130  is inserted into the clamp screw passage  126 , with the distal end  132  of the screw  130  residing in the hollow interior  120  of the ground lug  118  when the screw is installed. 
     A ground wire clamping chock  134  includes a threaded passage  136  therethrough, with the clamp screw  130  being threaded into the clamping chock passage  136 . As the ground wire clamp screw  130  does not advance axially relative to the clamp screw passage  126  due to the lack of threads therein, it will be seen that rotation of the clamp screw  130  results in axial travel of the clamping chock  134  along the screw  130 . The chock  134  cannot rotate relative to the ground lug  118 , due to its confinement between the two opposed walls  124  of the lug. 
     The clamping chock  134  is installed into the interior  120  of the ground lug  118  through the open floor  138  thereof in the embodiment  110  of  FIGS. 1 and 2 , with the open floor  138  disposed opposite the ground screw passage  126  and serving as an access opening for the grounding lug interior  120 . The ground wire clamp chock  134  preferably includes an angled or beveled ground wire contact portion  140 , which is offset laterally from the clamp screw passage  136  of the chock and the ground wire clamp screw  130  threaded therethrough. Alternatively, the ground wire contact portion may comprise a flat surface orthogonal to the axis of the ground wire clamp screw  130 , or may have some other configuration as desired. When the chock  134  is installed on the clamp screw  130 , the ground wire passage  122  is positioned between the ground wire contact portion  140  of the chock  134  and the intermediate wall  128  of the grounding lug portion  118 . Thus, as the ground wire clamp screw  130  is tightened in the chock  134 , the chock is pulled upwardly along the threaded shank of the screw  130  to clamp the ground wire G securely between the ground wire contact portion  140  of the chock  134  and the generally opposite sides or edges of the ground wire passage  122  through the grounding lug portion  118  of the device, generally as shown in  FIG. 2 . 
     The side elevation view in section of  FIG. 3  illustrates various modifications to the device, resulting in a second embodiment of an electrical bonding block  310 . The bonding block  310  of  FIG. 3  is configured generally similarly to the embodiment  110  of  FIGS. 1 and 2 , with corresponding components being identified by three digit numerals differing only in the first digit, e.g., the bonding block  110  of  FIGS. 1 and 2  vs. the bonding block  310  of  FIG. 3 . The electrical bonding block  310  of  FIG. 3  includes a bonding block body  312  having mutually opposed first and second electrical conductor terminals extending therefrom. Only the first connector  314  is shown in the elevation view of  FIG. 3 , but it will be understood that this portion of the device  310  is identical to the corresponding portion of the bonding block  110  of  FIGS. 1 and 2 . 
     An electrical grounding lug  318  having a hollow interior  320  extends from the body  312 , generally in the manner of the lug  118  and body  112  of the first embodiment  110 . The grounding lug  318  includes a ground wire passage  322 , which passes through the opposed lateral walls  324  (only one of which is shown in the sectional view of  FIG. 3 ) of the lug. However, it will be noted that the passage  322  of the embodiment  310  of  FIG. 3  differs from the passage  122  of the embodiment of  FIGS. 1 and 2 , with the passage  322  of  FIG. 3  including a concave, semicylindrical channel  323  formed in or adjacent to the intermediate wall  328  forming the roof or top of the grounding lug portion  318 . The ground wire channel  323  extends completely across the width of the grounding lug  318 , as shown by the solid body representation of the channel in the cross sectional view of  FIG. 3 . 
     An unthreaded ground wire clamp screw passage  326  is formed through the upper intermediate wall  328  of the lug  318 , with the ground wire clamp screw  330  installed in the clamp screw passage  326  as in the embodiment  110  of  FIGS. 1 and 2 . However, rather than having the distal end  332  of the screw  330  unsupported, as in the bonding block embodiment  110 , the grounding lug  318  of  FIG. 3  includes a closed floor  338  extending thereacross, serving as a distal support for the clamp screw  330 . The floor  338  includes a screw distal end passage  339  therein or therethrough, opposite the clamp screw passage  326 , with the distal end  332  of the screw  330  being captured within the passage  339  when the screw  330  is inserted completely into and through the hollow interior  320  of the grounding lug  318 . Thus, as the ground wire clamp screw  330  is rotated within its passage  326  through the upper wall  328  of the grounding lug  318 , the distal end  332  of the screw is captured or supported by the distal screw end passage  339  through the clamp screw support element or floor  328  of the device, relieving bending loads on the clamp screw  330  and the upper or lateral wall  328  through which the screw passes. 
     The ground wire chock  334  of the embodiment of  FIG. 3  also differs somewhat from the chock  134  of the embodiment of  FIGS. 1 and 2 . Rather than having a tapered or beveled ground wire contact surface, the chock  334  of  FIG. 3  includes a concave, semicylindrical ground wire contact portion  340 . The combination of the semicylindrical concavity of the ground wire channel  323  and the semicylindrical concavity of the ground wire contact portion  340  of the chock  334  results in a generally congruent, more closely conforming contact of the channel  323  and ground wire contact portion  340  with the cylindrical shape of the ground wire G. This provides greater contact area between the wire and the bonding block device  310  for better electrical conductivity, and also better distributes the contact pressures on the ground wire to reduce deformation and imposition of stress risers on the wire. It will be understood that the various embodiments shown in  FIG. 3  and described above may be incorporated in any of the other embodiments of the device as desired. 
       FIG. 4  of the drawings illustrates yet another embodiment of the present invention, comprising bonding block  410 . Much of the structure of the bonding block  410  of  FIG. 4  is identical with that of the bonding block  110  of  FIGS. 1 and 2 , with only the differing structure being described in the discussion of the bonding block  410  of  FIG. 4 . The bonding block  410  includes a bonding block body  412  having first and second electrical connector terminals, respectively  414  and  416 , extending therefrom. However, while the second terminal  416  extends rearwardly from the body  412  in the perspective of the drawing Fig., as in the case of the embodiments of  FIGS. 1 through 3 , it will be noted that the first terminal connector  414  is disposed orthogonally relative to the second terminal. This option may be provided with any of the bonding block embodiments of the present invention, as desired. It will also be noted that the specific configuration shown in solid lines in  FIG. 4  is not required, and that the first terminal connector  414  may be located as shown by the alternative orthogonal first connector position  414   a  or the coaxially disposed first connector position  414   b , both shown in broken lines in  FIG. 4 . 
     The bonding block  410  of  FIG. 4  also differs from the blocks of  FIGS. 1 through 3  in that the orientation of the ground wire passage  422  and ground wire clamp screw  430  of the grounding lug portion  418  are orthogonal to the orientation of those corresponding components shown in  FIGS. 1 through 3 . This configuration, wherein the ground wire clamp screw  430  is axially parallel to the alternative first connector  414   b  and its coaxially disposed or aligned second connector  416 , may be provided in any of the other embodiments of the present electrical bonding block, as desired. In the configuration of  FIG. 4 , the unseen distal end of the ground wire clamp screw  430  engages a support passage in the opposite, unseen lateral wall of the grounding lug  418 . Clearance for the installation of the ground wire clamp chock may be provided by leaving the inner wall of the grounding lug  418  open. 
       FIG. 5  of the drawings provides an illustration of still another embodiment of an electrical bonding block, comprising bonding block  510 . The bonding block  510  is generally similar to the bonding block  110  of  FIGS. 1 and 2 , having a bonding block body  512  with first and second terminals, respectively  514  and  516 , disposed thereon. The terminals may be coaxially aligned with one another, as shown, or may be orthogonal to one another, as in the embodiment of  FIG. 4 . The bonding lug portion  518  includes a hollow interior  520  having a ground wire passage  522  formed through the opposite walls  524  thereof. A ground wire clamp screw  530  extends through a clamp screw passage (not shown in  FIG. 5 , but similar to that shown for the embodiment  110  in  FIG. 2 ) formed in the transverse intermediate wall  528 , and engages a ground wire clamp chock  534  within the hollow interior  520  of the bonding lug  518 . 
     The above-described configuration is essentially the same as that described in other embodiments of the present electrical bonding block. However, it will be noted that the bonding block  510  of  FIG. 5  differs from other embodiments of the present invention by placing the bonding block body  512  essentially coplanar with the bonding lug  518 . This lowers the overall height of the device, providing a more compact installation. Sufficient clearance is provided between the terminals  514  and  516  and the underlying base of the device to allow the larger connector end of the coaxial cable to be connected to the terminals, as required. 
       FIG. 6  provides an illustration of a conventional bonding block B of the prior art. The grounding lug L of the bonding block B includes a ground wire passage P therethrough, with a ground wire clamp screw S disposed orthogonally to the passage P. It will be noted that in the conventional bonding block B, the ground wire clamp screw S lies in the same plane as the ground wire passage P. Thus, the screw S engages a ground wire directly as it passes through the ground wire passage P, with the direct engagement of the ground wire screw against the ground wire resulting in the production stress risers, work hardening, and general reduction in the security of the installation of the ground wire in the bonding block. 
     In conclusion, the electrical bonding block of the present invention in its various embodiments provides a much more secure means of electrically bonding a ground wire to the electrical ground of another electrical conductor or device. The reduction of high point pressures on the relatively soft metal of the ground wire greatly reduces the deformation of the wire and resulting stress risers, thus reducing work hardening of the ground wire, stress corrosion, and other factors which cause the connection to loosen and the electrical continuity of the ground wire connection to be lost. Accordingly, the electrical bonding block will prove to be a most useful advance in such devices. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.