US3761867A

US3761867A - Insulation and oxide piercing contact means

Info

Publication number: US3761867A
Application number: US00219079A
Authority: US
Inventors: J Churla
Original assignee: Thomas and Betts Corp
Current assignee: ABB Installation Products Inc
Priority date: 1972-01-19
Filing date: 1972-01-19
Publication date: 1973-09-25
Anticipated expiration: 1990-09-25
Also published as: DE7301195U; SE380682B; NL7300375A; DE2301625A1; BE794320A; FR2182808B1; JPS4882383A; AU5078973A; FR2182808A1; GB1372833A; CA979091A

Abstract

Contact means for improving the contact between acjacent conductive members comprising a substantially flat, multiple toothed member having a selectively proportioned slotted aperture arranged to permit the contact means to be disposed about a binding post or similar fastening element. The toothed projections which may be disposed on at least a portion of either one or both surfaces of the contact means are selectively dimensioned to bit into and engage the adjacent conductive surface of one or more conductors urged thereagainst as the contact means is interposed between the conductor and the adjacent conductive member. The contact means may be formed either as discrete, single apertured members, or as multiapertured members wherein the apertures are selectively spaced preferably to bridge two or more adjacently disposed binding posts or the like. The contact means may be provided in strip form and selectively scored or recessed to enable convenient separation of the interconnected members.

Description

I INSULATION AND OXIDE PIERCING CONTACT MEANS John J. Churla, Belle Mead, NJ.

[73] Assignee: Thomas & Betts Corporation,

Elizabeth, NJ,

22 Filed: Jan. 19,1972

21 Appl. No.: 219,079

[75] Inventor:

[451 Sept. 25, 1973 Primary Examiner-Joseph H. McGlynn Att0rneyDavid Teschner et al.

[57] ABSTRACT Contact means for improving the contact between acjacent conductive members comprising a substantially flat, multiple toothed member having a selectively proportioned slotted aperture arranged to permit the com tact means to be disposed about a binding post or similar fastening element. The toothed projections which may be disposed on at least a portion of either one or both surfaces of the contact means are selectively dimensioned to bit into and engage the adjacent conductive surface of one or more conductors urged thereagainst as the contact means is interposed between the conductor and the adjacent conductive member. The contact means may be formed either as discrete, single apertured members, or as multi-apertured members wherein the apertures are selectively spaced preferably to bridge two or more adjacently disposed binding posts or the like. The contact means may be provided in strip form and selectively scored or recessed to enable convenient separation of the interconnected members.

6 Claims, 12 Drawing Figures [52] US. Cl 339/98, 85/51, 151/35, 339/277 R [51] Int. Cl H011 9/08 [58] Field of Search 339/95, 97-99, 339/277; 85/51, 50; 151/35 [56] References Cited UNITED STATES PATENTS l,847,689 3/1932 Gribbie 339/95 A 2,716,247 8/1955 Poupitch .l l5I/35 2,069,402 2/1937 Cowlin l5l/35 2,946,039 7/l96O Grunwald et al. 339/269 FOREIGN PATENTS OR APPLICATIONS 375,691 6/1932 Great Britain 339/277 R 1,047,764 11/1966 Great Britain 339/95 A Patented Sept. 25, 1973 3,761,861

3 Sheets-Sheet 2 Patented Sept. 25, 1973 I5 Sheets-Sheet 1.5

FIG.

FIG. 12

INSULATION AND OXIDE PIERCING CONTACT MEANS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is directed to the field of contact means and principally to means for improving the electrical contact between adjacent conductive members.

2. Description of the Prior Art As a result of the increasing use of aluminum conductor in many wiring applications there has been a need for an improved connector means for coupling either one aluminum conductor to another or coupling the aluminum conductor to a further conductive member such as a support strip, bus bar, electrical device, or the like. It is well known that such aluminum wire comprises a relatively thin oxide coating about the outer surface thereof which must be penetrated or removed to permit an electrical connection to be made thereto. Because of the metallurgical characteristics of aluminum, merely cleaning the outer surface prior to establishing a connection therewith is generally ineffective since a new oxide coating may reappear on the wire surface within a relatively short time after the surface has been cleaned, and exposed to the atmosphere, thereby detrimentally affecting the consequent connection because of the high resistance developed between the aluminum conductor and the adjacent connector surface. Prior art attempts to provide an improved contact surface, as exemplified, for example, in US. Pat. No. 2,372,653, issued to A. L. Becket, and US. Pat. No. 1,847,689, issued to J. M. Gribbie, employed a series of circumferentially disposed teeth or off-set protrusions adapted to engage and bite into the insulation or coating disposed about the conductor positioned thereagainst as a threaded fastener was tightened about the assembly incorporating the conductor and such device. Although such prior art devices did provide a measure of contact with the adjacent conductor surface, the contact was generally limited to the area defined by the relatively few projections actually engaging the adjacent conductor surface, thus severely limiting the current carrying capacity of the electrical connection so formed. It should also be noted that such prior art washers, in many cases, were provided with a completely enclosed aperture which necessitated the removal of the fastening means or binding post to permit such washer to be engaged therewith, such operation being highly inconvenient, time-consumingand costly. The employment of teeth or protrusions on the underside of the enlarged head portion of a threaded fastener or stud generally failed to overcome the above-mentioned difficulties since the teeth or protrusions necessarily rotated with the fastener upon the tightening thereof, and merely scored or grooved the adjacent conductor surface which, in many cases, served to disadvantageously reduce the effective crosssectional area of the conductor, resulting in a reduction of the current carrying capacity thereof.

SUMMARY OF THE INVENTION The invention overcomes the difficulties and limitations noted above with respect'to such prior art devices by providing a low cost, economical, conveniently employable toothed contact means which may be readily adaptable for use with existing components to afford a superior electrical and mechanical connection to either copper or aluminum wire. The device comprises essentially a flat metallic member which may be formed of electrically conducting material and provided with a plurality of pointed teeth on at least a portion of either one or both surfaces thereof. The device is suitably apertured and slotted to permit its disposition over an existing stud, binding post, or other similar fastening means while obviating the necessity for removing such fastening means from the adjacent support member, bus bar, or other receiving member. Thus, the device may be conveniently employed to increase the versatility of existing electrical devices where such devices heretofore have been designed primarily for use with copper conductors and wherein it is desired to permit their employment with aluminum conductors. The device may be formed with either a single slotted aperture or a plurality thereof suitably spaced to permit the use of the device as a bridge between existing studs or mounting members. The disclosed device may also be formed as a series of interconnected members with a suitably weakened portion between adjacent members to permit the separation of one member from another, thus permitting the device to be conveniently manufactured, stored and used in strip form. The device may be interposed either between the base plate of the support means and the respective conductor or conductors, or, in the alternative, between a plurality of conductors to advantageously increase the area of contact therebetween. The teeth may either be formed from the base material of affixed thereto, and may extend from either one or both surfaces of the device. The tooth height may be suitably dimensioned to permit sufficient engagement and penetration into the conductive portion of, for example, aluminum conductor wire, to permit electrical contact thereto, despite the existence of an oxide film or other insulating material over the outer surface thereof. It is therefore an object of this invention to provide an improved electrical contact surface.

It is another object of this invention to improve the contact between an existing electrical conductor and an adjacent conductive member.

It is another object of this invention to provide contact means for improving the electrical contact between adjacent conductive members.

- It is a further object of this invention to provide means for increasing the versatility of existing electrical systems.

It is another object of this invention to provide means for establishing reliable electrical contact between an aluminum conductor and a further conductive memher.

It is still a further object of this invention to provide a toothed contact arranged to pierce the oxide coating about and engage the conductive portion of an aluminum conductor.

It is yet another object of this invention to provide a plurality of interconnected toothed contact means in conveniently employable strip form.

It is yet another object of this invention to provide slotted contact means having a plurality of teeth disposed on at least a portion of either one or both surfaces thereof to increase the electrical contact between adjacent conductive surfaces.

Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose, by way of example, the principle of the invention and the best mode contemplated for carrying it out.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of insulation and oxide piercing contact means constructed in accordance with the concepts of the invention.

FIG. 2 is a front elevational view of the device of FIG. 1 showing its use in a typical assembly.

FIG. 3 is a front elevational view of the device of FIG. 1 showing a further use thereof in a typical assembly.

FIG. 4 is a front elevational view, in section, of a further embodiment of an insulation and oxide piercing contact means constructed in accordance with the concepts of the invention, as employed in a typical assembly.

FIG. 5 is a perspective view of another embodiment of insulation and oxide piercing contact means constructed in accordance with the concepts of the invention.

FIG. 6 is a perspective view of still a further embodiment of insulation and oxide piercing contact means constructed in accordance with the concepts of the invention.

FIG. 7 is a perspective view of the device of FIG. 5 showing the use thereof in a typical electrical assembly.

FIG. 8 is a fragmentary perspective view, partly in section, showing an embodiment of the toothed projections of the device of FIG. 1.

FIG. 9 is a fragmentary perspective view, partly in section, showing a further embodiment of the toothed projections of the device of FIG. 1.

FIG. I0 is a fragmentary perspective view, partly in section, of still a further embodiment of insulation and oxide piercing contact means constructed in accordance with the concepts of the invention.

FIG. 11 is a fragmentary perspective view, partly in section, of still another embodiment of insulation and oxide piercing contact means constructed in accordance with the concepts of the invention.

FIG. 12 is a perspective view of yet another embodiment of insulation and oxide piercing contact means constructed in accordance with the concepts of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIGS. 1, 2 and 3 there is shown insulation and oxide piercing contact means constructed in accordance with the concepts of the invention. Means 20 comprises a first surface 22 and a second surface 24, said surfaces defining generally the thickness thereof. A plurality of pointed protrusions 26 extend outwardly from both

surfaces

22, 24 substantially as shown, and are disposed over portions of the area defined thereby. Such protrusions 26, may, of course, be disposed over substantially the entire area defined thereby, if necessary or desirable. A selectively proportioned slot 28 extends between and communicates with, respectively, an outer edge 30 of contact means 20 and a transverse aperture 32 extending between the

surfaces

22 and 24. Although contact means 20 is shown as having a substantially rectangular configuration, other suitable contours such as a generally round, oval or elliptical configuration may be readily employcd without departing from the spirit of the invention and within the concepts herein disclosed. As may electrically conducting sheet stock such as, for example, copper, brass, aluminum, or other suitable metals. Because of the inherent resiliency of such materials, contact means 20 may thus be conveniently urged over the body portion 34 of an existing fastener such as 36 (FIG. 2) where the width of the slot 28 is somewhat less than the diameter of the body portion 34 of fastener 36. The diameter of aperture 32 is proportioned to conveniently accept the body portion 34 of fastener 36 therethrough with a slot clearance thereabout. Thus, the fastener 36 may be advanced into or retracted from its re ceiving aperture 38 in an associated support member 40 (FIG. 2) without disturbing the alignment or position of contact means 20. Once attached to the fastener 36, contact means 20 is effectively prevented from becoming disassociated therewith because of the restrictive dimensions of slot 28. Thus, the assembly as shown in FIG. 2 may be repeatedly disassembled and reinstated without fear of loss of contact means 20. In use, it is merely necessary to retract the fastener 36 sufficiently to permit the introduction of a conductor such as 42 intermediate the contact means 20 and the head 44 of fastener 36. Fastener 36 is thereafter tightened down into the support member 40 causing the conductor 42 to be urged against the upper protrusions 26 on contact means 20 causing said protrusions 26 to pierce the outer surface of conductor 42 and engage the inner conductive portion 46 thereof. In the event the conductor 42 is covered with an insulation coating, as is commonly employed with many copper conductors, or an oxide coating developed over the outer surface of a typical aluminum conductor, effective electrical contact may thus be made to the conductive portion thereof, the height of protrusions 26 being selectively chosen to afford adequate piercing in such event. Simultaneously, the lower protrusions 26 disposed on surface 24 of contact means 20 are caused to engage and bite into the adjacent surface 48 of support member 40. Thus, a secure mechanical and electrical connection is established between the conductor 42 and the support member 40. The fastener 36 may therefore be formed of nonmetallic and nonelectrically conducting material which, in many applications, may be highly desirable, since the electrical connection thus established is completely independent of the material from which the fastener 36 is formed. A further electrical joint employed contact means 20 is shown in FIG. 3. Here, means 20 is shown interposed between two

conductive elements

50 and 52, respectively, each of said elements having been wrapped about its respective portion of the body 54 of a fastener 56 threadably engaged with a support member 58. As shown, the upper conductive element 50 may be covered with either conventional insulating material or an oxide coating, white the lower conductive element 52 may be relatively free of such coating. It may be appreciated from an examination of FIG. 3 that it would, of course, be immaterial whether either or both of the

conductive elements

50, 52 where insulated or bar since an electrical connection between said

elements

50, 52 is established by the penetration of the respective protrusions 26 into the conductive portion thereof, thus advantageously avoiding the necessity for laboriously cleaning, scraping or otherwise exposing the conductive surface of such conductive elements prior to assembly. The adjacent

conductive elements

50, 52 may thus be electrically interconnected without the necessity for providing an electrically conducting fastener 56 or electrically conducting support member 58. However, to provide a further electrical connection between the

conductive elements

50, 52 and support member 58 where such support member 58 is formed of electrically conducting material, an additional contact means such as may be interposed between the lower conductive member 52 and the upper surface 60 of support member 58, providing an assembly essentially similar to that described above with respect to FIG. 2. The protrusions 26 may take on any one of a number of suitable forms, some examples of which are shown in FIGS. 8 and 9. For example, in FIG. 8 protrusions 62 are formed essentially of triangular elements each having a plurality of cutting surfaces advantageously adapted for piecering and penetrating oxide or insulation coated conductors. The protrusions 62 may, of course, be disposed in either random or regular fashion about the adjacent surface as necessary or desirable. Alternatively, either, or both surfaces of contact means 20 may be lanced to form protrusions such as those shown at 64 in FIG. 9. It will, of course, be readily apparent to those skilled in the art that many other conventional or commonly employed tooth forms may be readily provided without departing from the spirit of the invention.

Turning now to FIG. 4 there is shown a typical use of contact means 66 constructed in accordance with the concepts of the invention and comprising a plurality of pointed protrusions or teeth 68 on a portion of a single surface thereof. This arrangement may be conveniently employed to provide an electrical coupling or connection between a pair of conductors such as 70, 72 substantially in the manner illustrated. To establish the il lustrated connection, contact means 66 is disposed over the body portion 76 of fastener 74 with the nontoothed surface of contact means 66 being disposed adjacent the head portion 78 of fastener 74. The

conductors

70, 72 are then interposed between the toothed surface 80 of contact means 66 and a support member 82 adapted to receive the fastener 74. Fastener 74 is then tightened into the support member 82 causing the contact means teeth 68 to penetrate the

conductors

70, 72 and establish an electrical connection therebetween, contact means 66 serving as a conductive bridge between said

conductors

70, 72. Where the fastener means 74 is formed of conductive material and is engaged within a conductive support member 82 an electrical connection may be established between the

conductors

70, 72 and the support member 82 in a similar manner. In this case, the conductive path would be from

conductors

70 and 72 through contact means 60 to the head portion 78 of fastener means 74, through the body portion 76 of fastener means 74 and then into the support member 82. Thus,

conductors

70 and 72 may have disposed over their outer surface either electrical insulation as shown, or an oxide coating, yet an adequate electrical connection may be made therewith as in the manner stated above.

Referring now to FIGS. 5 and 6 there are shown further embodiments of contact means constructed in accordance with the concepts of the invention. Contact means 84 illustrated in FIG. 5 is provided with a pair of selectively spaced slotted

apertures

86, 88 opening towards an outer edge 90 of means 84. Both the upper and

lower surfaces

92, 94 of contact means 84 are provided with pointed protrusions 96 similar to protrusions 26 of contact means 20 shown in FIG. 1. Although protrusions 96 are shown disposed on both contact means

surfaces

92, 94, they may be limited to a single surface or a portion of each of said surfaces as necessary or desirable. Contact means 84 may be employed in a manner shown, for example, in FIG. 7, wherein the spacing between

apertures

86 and 88 of contact means 84 have been dimensioned to approximate the spacing between a pair of binding posts such as 98 and 100 shown attached to a typical electrical switch box 102. To effect the assembly shown it is necessary merely to loosen the

binding posts

98 and 100 sufficiently to permit the insertion of contact means 84 between the binding post heads and the body portion 104 of box 102. One or more conductors such as 106, 108 may then be at least partially wrapped about the body portion (not shown) of bidning posts 98, 100, intermediate the head of said binding posts and contact means 84, and the

binding posts

98, 100 thereafter tightened down to cause the engaged portions of

conductors

106, 108 to be forced against the protrusions 96 of contact means 84, said protrusions 96 thus piercing the outer surface of said conductors 106, 1118 and engaging the conductive portion therewithin.

Conductors

106, 108 may be selectively stripped, substantially as shown, prior to the assembly, but this operation is not necessary since the protrusions 96 may be suitably proportioned to have a length sufficient to penetrate the full outer insulation covering of said

conductors

106, 108 and any oxide coating which may be present and penetrate the inner conductive portion thereof. Contact means 84 may be supplied as individual units as shown in FIG. 5 or in strip form, substantially as shown in FIGS. 10 and 11. In the strip configuration illustrated in FIG. 11 there is provided separating means in the form of a plurality of generally transversely extending recessed portions 110 each disposed intermediate a pair of contact means 84. Recessed portion 110 is appropriately dimensioned to provide a generally frangible area adjacent thereto, thereby facilitating the removal of one of said contact means 84 from the remaining strip merely by bending or otherwise deforming the strip about such recessed portion 110. A similar arrangement is illustrated in FIG. 10 wherein there is shown a plurality of interconnected contact means 112 each constructed in a manner similar to that illustrated with respect to contact means 20 shown in FIG. 1. The juncture between each pair of contact means 112 is defined by a recessed portion 114 similar to the recessed portion 110 shown in FIG. 11, and in a similar manner provides a means for separating one of said contact means 112 from the adjacent strip. Contact means 84 shown in FIG. 5 may be modified to provide an arrangement such as that shown in FIG. 6 where there is illustrated a contact means 116 having a pair of selectively spaced, slotted apertures 118, 1120 opening to opposing

edges

122, 124 of contact means 116. Although the contact means 84 and 116 illustrated in FIGS. 5 and 6, respectively, are shown with only a pair of spaced apertures therethrough, each of said contact means may be provided with additional apertures where necessary or desirable and within the concepts of the invention. A pair of contact means such as 84 may be joined together in a backto-back arrangement similar to that shown in FIG. 12. To facilitate the separation of one of said contact means 84 from the other, there is provided a longitudinally extending recessed portion 126 selectively proportioned to permit separation of said contact means 84 in a manner similar to that described above with respect to the strip configurations shown in FIGS 10 and 12. It will, of course, be readily apparent to hose skilled in the art that the separation of adjacent contact means provided either in strip form, as shown in FIGS. 10 and 11, or in connected pairs, as shown in FIG. 12, may be accomplished by means other than the use of a recessed portion such as 110 and 114 shown in FIGS. 11 and 10, respectively, and may comprise, for example, perforations (not shown) or relatively narrow web portions (not shown) intermediate each pair of contact means. To facilitate the introduction of a contact means such as 20, or any of the other contact means heretofore described, over the body portion of a mounting stud or fastener, a contoured portion 128 may be provided adjacent the area of communication between slot 28 and the outer edge 30 contact means 20, as shown in FIG. 1. The contour may take the form of a tapered surface, chamfer, radius or other suitable configuration.

The embodiments of the invention in which an exclusive property or priviledge is claimed are defined as follows:

1. Insulation and oxide piercing contact means comprising: a body member formed of flat electrically conducting metallic material and having a first surface and a second surface, said surfaces defining the thickness of said body member, at least one smoothly contoured outer edge, at least one selectively proportioned aperture extending between said first and said second surfaces, at least one smoothly contoured inner edge at least partially defining the periphery of said aperture, and at least one restrictively proportioned slot extending between and communicating with its associated aperture and at least a portion of said outer edge of said body member; and a plurality of discrete, generally sharply pointed protrusions having a predetermined length and extending outwardly generally normal to the plane of said body member, said protrusions being disposed generally uniformly over substantially the entire area defined by at least one of said first and said second surfaces, said protrusions being confined solely to the area intermediate but not including said inner edge and said outer edge of said body member and arranged in such close proximate relationship one to another as to penetrate the outer surface of and selectively engage the interior of a conductor impaled on said protrusions to provide intimate electrical contact between said body member and such conductor 2. Contact means as defined in claim 1 wherein said body member has at least two apertures in selectively spaced arrangement extending between said first and said second surfaces thereof, and at least two slots, each extending between and communicating with its associated aperture and a portion of said outer edge of said body member.

3. Contact means as defined in claim 2 further comprising separating means disposed on said body member and aligned to facilitate the separation of said body member into discrete contact means each having a single aperture and an associated slot.

4. Contact means as defined in claim 3 wherein said separating means comprises a generally transversely extending recessed portion having a depth selectively proportioned to provide a frangible zone thereat.

5. Contact means as defined in claim 2 further comprising separating means disposed on said body membeer and aligned to facilitate the separation of said body member into discrete contacts each having at least a pair of said apertures and their respective associated slots.

6. Contact means as defined in claim 5 wherein said separating means comprises a generally transversely extending recessed portion having a depth selectively proportioned to provide a frangible zone thereat.

Patent'No. 3,761,867 Dated September 25 1973 Inventor(s) John J, Churla It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Abstract of the Disclosure, line 1 -acjacent should be er adjacent t:-

Column 4, line 13 "slo't" should be aslight Column 4, line 51 "employed" should be K-v employing Column 4, line 63 "bar" should be bare Column 6, line 19 "bidning" should be binding Column 7, line 6 "hose" should be those I Signed and sealed this 25th day of December 1973.

(SEAL) Attest:

EDWARD M.FLETGHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents FORM 1 0-1050 (10-69) USCOMM-DC E0376-P69 V a u.s. GOVERNMENT PRlNTING pmc; 1196's o-aes-asl;

Claims

1. Insulation and oxide piercing contact means comprising: a body member formed of flat electrically conducting metallic material and having a first surface and a second surface, said surfaces defining the thickness of said body member, at least one smoothly contoured outer edge, at least one selectively proportioned aperture extending between said first and said second surfaces, at least one smoothly contoured inner edge at least partially defining the periphery of said aperture, and at least one restrictively proportioned slot extending between and communicating with its associated aperture and at least a portion of said outer edge of said body member; and a plurality of discrete, generally sharply pointed protrusions having a predetermined length and extending outwardly generally normal to the plane of said body member, said protrusions being disposed generally uniformly over substantially the entire area defined by at least one of said first and said second surfaces, said protrusions being confined solely to the area intermediate but not including said inner edge and said outer edge of said body member and arranged in such close proximate relationship one to another as to penetrate the outer surface of and selectively engage the interior of a conductor impaled on said protrusions to provide intimate electrical contact between said body member and such conductor.

2. Contact means as defined in claim 1 wherein said body member has at least two apertures in selectively spaced arrangement extending between said first and said second surfaces thereof, and at least two slots, each extending between and communicating with its associated aperture and a portion of said outer edge of said body member.

5. Contact means as defined in claim 2 further comprising separating means disposed on said body member and aligned to facilitate the separation of said body member into discrete contacts each having at least a pair of said apertures and their respective associated slots.