US3892460A

US3892460A - Contact means

Info

Publication number: US3892460A
Application number: US443912A
Authority: US
Inventors: Hyman Izraeli
Original assignee: Thomas and Betts Corp
Current assignee: ABB Installation Products Inc
Priority date: 1974-02-19
Filing date: 1974-02-19
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01
Also published as: CA1025966A; DE2506791A1; SE399991B; GB1468100A; DE7504880U; JPS5526593B2; BE825714A; AR202677A1; BR7501020A; NL7501985A; DE2506791B2; SE7501874L; JPS50118286A; FR2330157A1; ES434831A1; ZA751046B

Abstract

Contact means for an electrical connector comprises a slotted metallic member having selectively configured leg portions extending from a base portion, each of said leg portions being skewed about its longitudinal axis at a given angle to the plane of the base portion so that the force of a conductor inserted within the slot between adjacent leg portions will cause such leg portions to be rotationally displaced in a similar direction from their original position while providing secure mechanical and electrical engagement between the conductor and the inner edges of the leg portions defining said slot. The rotational displacement of the leg members provides increased slot width variation while maintaining a substantially constant pitch between the leg portion to permit the accommodation of a wide range of conductor sizes therebetween without causing undue stress or permanent deformation of the leg portions.

Description

United States Patent [191 Izraeli CONTACT MEANS Hyman Izraeli, West Caldwell. NJ.

[73] Assignee: Thomas & Betts Corporation,

Elizabeth, NJ.

22 Filed: Feb. 19,1974

21 Appl. No.: 443,912

[75] Inventor:

Primary Examiner-Joseph H. McGlynn Attorney, Agent, or FirmDavid Teschner; Jesse Woldman July 1, 1975 [57] ABSTRACT Contact means for an electrical connector comprises a slotted metallic member having selectively configured leg portions extending from a base portion, each of said leg portions being skewed about its longitudinal axis at a given angle to the plane of the base portion so that the force of a conductor inserted within the slot between adjacent leg portions will cause such leg portions to be rotationally displaced in a similar direction from their original position while providing secure mechanical and electrical engagement between the conductor and the inner edges of the leg portions defining said slot. The rotational displacement of the leg members provides increased slot width variation while maintaining a substantially constant pitch between the leg portion to permit the accommodation of a wide range of conductor sizes therebetween without causing undue stress or permanent deformation of the leg portions.

12 Claims, 10 Drawing Figures TATFHTFPJUL 1 SHEET 'IIIIIIIII CONTACT MEANS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is directed to the field of electrical connectors and principally to improved contact means therefor.

2. Description of the Prior Art In recent years there has been an increasing use of electrical connectors in which a slotted metallic contact member is employed to provide electrical contact between two or more insulated electrical conductors inserted within the slots of the contact member. The contact member generally comprises a flat metallic element suitably slotted to provide a series of individual. coplanar blade members which are caused to spread apart within the plane of the element under the influence ofa conductor inserted within a slot intermediate each two blade members. The sides of the slots defined by the edges of the blade members. The sides of the slots defined by the edges of the blade members are designed to cut through the insulation and contact the conductive portion of the conductor. Such devices are exemplified in US. Pat. No. 3,202,957 issued Aug. 24. I965 to E. E. Leach; US. Pat. No. 3,388,370 issued June ll, 1968 to R. A. Elm; US. Pat. No. 3,521,22l issued July 2|, I970 to G. B. Lenaerts et a1; and US. Pat. No. 3.605.072 issued Sept. 14. 1971 to Driscoll. A serious drawback with this type of construction is the manner in which the blade members must be deflected to accommodate the wires inserted within the slotted portions thereof. That is, the web portion joining the blade members one to another is subjected to severe tensile and compressive stresses during such assembly which, in many cases. results in permanent deformation or fracture of the blade members thereby seriously limiting the effectiveness of the electrical connection formed thereby. In other cases as, for example, with the Lenaerts device. the blade members on either side of the conductor receiving slot are deflected in opposite directions out of the plane of the base member to accommodate the inserted wire. Accordingly, a relatively low force is exerted against the conductor after inser tion, often leading to failure of the electrical connector after a period of continued use. The above mentioned form of contact blades are thus inherently unable to provide the necessary resiliency together with the high continuous contact pressure required to effect a reliable and permanent electrical connection.

SUMMARY OF THE INVENTION The invention overcomes the disadvantages and limitations noted above with respect to prior art devices by providing a contact means for an electrical connector which is more positive, secure, and more reliable than such prior art devices. The contact means is formed from a metallic member suitably slotted to provide a plurality of leg portions extending from the base portion of the contact means in generally spaced parallel relationship. Each of the leg portions is skewed at a given angle about its longitudinal axis out of the plane of the base portion to induce each leg portion to deflect or pivot about its longitudinal axis while essentially preserving the initial pitch between leg portions when a force is exerted against the sides thereof as by the insertion of a conductor within a conductor receiving slot intermediate adjacent leg portions. The rotational displacement of the leg portions thus permits a wide range of conductor sizes to be readily accommodated within the slots of the contact member without unduly stressing the member or causing permanent deformation or fracture thereof while maintaining secure electrical and mechanical engagement between the sides of the slots and the surface of the conductor. Each of the leg members may have either a flat or undulating configuration, in transverse section, the latter configuration providing increased longitudinal stiffness for employment preferably with the larger conductor sizes. Each of the slots may have either a uniform width throughout its length or may be appropriately configured to provide a conductor receiving zone originating at the mouth of the slot and extending inwardly towards the base portion for a first given length, and a transition zone of narrower width than the conductor receiving zone to pre vent further insertion of the conductor within the slot while providing a total slot length designed to regulate the deflection characteristics of each leg portion. The contact member may comprise leg portions aligned in either a single or double row, the latter arrangement providing opposing pairs of leg portions each independently pivotably about its longitudinal axis while providing multiple engagement with each of the conductors. Accordingly, the stock thickness from which the contact member is fabricated may be reduced in the latter arrangement, which will advantageously increase the resiliency of the leg portions and reduce the insertion force required to seat a conductor within an associated conductor receiving slot. It is therefore an object of this invention to provide improved contact means.

It is another object of this invention to provide a novel means for electrically interconnecting insulated conductors.

It is a further object of this invention to provide a rapid. inexpensive, and reliable means for electrically interconnecting a plurality of insulated conductors.

It is yet another object of this invention to provide a slotted metallic contact member arranged to electrically interconnect a plurality of conductors.

It is yet a further object of this invention to provide a slotted metallic contact member having independently deflectable conductor engaging leg portions.

It is still a further object of this invention to provide a slotted metallic contact member arranged to accept a wide range of conductor sizes, by the employment of pivotingly deflectable leg portions.

Other objects and features 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 In the Drawings:

FIG. 1 is a front elevational view ofa contact means constructed in accordance with the concepts of the invention.

FIG. 2 is a top plan view, in section, of the device of FIG. 1 taken along the line 2-2 thereof.

FIG. 3 is a front elevational view ofa further embodiment of contact means constructed in accordance with the concepts of the invention.

FIG. 4 is a front elevational view, partly cut away and partly in section, showing the device of FIG. 3 as employed in an electrical connector.

FIG. 5 is a side elevational view, partly in section. of the device of FIG. 4 taken along the line SS of FIG. 4.

FIG. 6 is a top elevational view. partly cut away and partly in section, of the device of FIG. 2, showing the displacement of the individual leg portions thereof upon engagement with conductors inserted within the slots of the contact means.

FIG. 7 is a fragmentary diagrammatic top plan view of a portion of the device of FIG. 6 showing the forces applied thereto upon engagement with one or more conductors.

FIG. 8 is a front elevational view of a further embodiment of a contact means constructed in accordance with the concepts of the invention.

FIG. 9 is a fragmentary front elevational view of yet another embodiment of a contact means constructed in accordance with the concepts of the invention.

FIG. 10 is a top plan view, in section, of a further embodiment of a contact means constructed in accordance with the concepts of the invention.

Similar elements are given similar reference characters in each of the respective drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

Turning now to FIGS. 1 and 2 there is shown a contact means constructed in accordance with the concepts of the invention and comprising a metallic member 22 having a base portion 24 and a plurality of leg portions 26 integral with and extending from the base portion 24 in generally spaced parallel relationship. Although the contact means 20 is shown as an essentially U-shaped member having a double row of leg portions 26, (see FIG. 2) the member 22 may comprise simply a single element representing essentially half of the U-shaped member shown in FIG. 2 and comprising a single row of leg portions 26 or, alternatively, may comprise two or more such elements suitably positioned in spaced parallel relationship. It will thus be understood that in each of the embodiments to be described hereafter the U-shaped member may be replaced by a single element as hereinabove discussed. Intermediate each two adjacent leg portions 26 is a suitably proportioned slot 28 separating the leg portions 26 one from another. The slots 28 may of course be all of equal width, where, for example, the contact means 20 is designed to accept a particular single range of conductor sizes or, alternatively, may be of differing widths whereby each of said slots 28 is adapted to accept a particular range of conductor sizes. In the latter case, by way of example, one or more of the slots 28 may be adapted to receive conductors ranging from No. 18 to No. 22 A.W.G. while one or more of the remaining slots 28 may have a width adapted to receive conductors ranging from No. 16 to No. 12 A.W.G. Commensurate with such structure there may be provided suitable markings or other indicia (not shown) on or in conjunction with the contact means 20 to designate the particular conductor sizes associated with each of the slots thereof. Additionally, the slots 28 may either all be of the same length, or may have differing lengths selectively proportioned to provide varying deflection characteristics with respect to each of the leg portions 26, where necessary or desirable. The entrance to each slot 28 may be either straight (not shown) or tapered, as at 30, the latter configuration providing for more convenient entry of a conductor into an associated slot 28. The contact means 20 is preferably stamped from flat stock so as to provide relatively sharp edges along the sides defining each of the slots 28 to permit shearing through the conductor insulation, where appropriate. and maintaining firm electrical and mechanical engagement with the conductive portion therewithin. Although each of the slots 28 is shown in FIG. I as having an essentially uniform width throughout its length, this arrangement may be modified as shown, for example, in FIG. 3 wherein there is illustrated a plurality of multi proportioned slots 32 each comprising essentially two sections consisting of a first or conductor receiving zone 34 and a second or transition zone 36, the width of the second zone 36 being somewhat less than the width of the conductor receiving zone 34. In this manner, the conductors engaged within the slots 32 may be confined to the area generally adjacent the free end of the leg portions 26 of the contact means but well within the slots 32 while the total length of the slots 32 may be suitably proportioned to provide the necessary deflection characteristics. An application of this embodiment is illustrated in FIG. 4 where a plurality of conductors 38 are shown constrained within the conductor receiving zone 34 of the slots 32 and are effectively prevented from entering the reduced width portions of the slots 32 comprising the transition zone 36. A further embodiment of the slotted portion of the contact means is illustrated in detail in FIG. 8 where there is shown a plurality of slots 40 in which a transition zone 39 is followed by an enlarged opening 42 to reduce the width of material between adjacent openings 42 thereby providing a necked-down portion 44 thereat further increasing the resiliency of each of the leg portions where necessary or desirable. The slots 28, although shown as having essentially straight sidewalls in FIG. 1, may be modified to provide other sidewall configurations for employment with conductors having other than round cross sectional configurations. As shown in FIG. 9, slots 45 comprise convexedly formed sidewalls 46 which may be found especially useful for engaging square or rectangular conductors. It will of course be readily appreciated by those skilled in the art that a combination of linear and arcuate slot sidewall configurations may be employed in similar fashion without departing from the spirit of the invention and within the concepts herein disclosed.

Returning now to the embodiments illustrated in FIGS. 1 and 2, the blade member 22 is shown as having a generally wavy or undulating configuration wherein each of the leg portions 26 may be best described as being skewed out of the plane of the base portion 24 where such plane is defined generally as extending through the center of each of the leg portions 26 as shown for example by the dotted line 48 in FIG. 7. Each of the leg portions 26 is skewed about its longitudinal axes at a given angle A (See FIG. 7) out of the plane of the base portion and about its center designated in FIG. 7 by the letter B. It should be understood that only a portion of one half of the metallic member 22 is illustrated in FIG. 7, namely, the leg portions 26a of the upper half as viewed in FIG. 2, and that the leg portions 26b of the lower half thereof is arranged symmetrically therewith but in opposing angular relationship thereto so that the leg portions 26b are disposed generally complimentary to the leg portions 260. In the particular embodiment illustrated in FIGS. I and 2 it should be understood that the base portion 24 of the member 22 is provided with the same wavy or undulating configuration as are the leg portions 26 although. as an alternative thereto. the base portion 24 may be fabricated as an essentially flat element while the leg portions 26 are twisted or skewed out of the plane thereof to provide a similar arrangement. However. it has been found that each of the leg portions 26 is strengthened in the longitudinal direction where the respective leg portion bends are continued down to and through the base portion 24 so that any tendency of the leg portions 26 to buckle or fold under the force exerted against the conductors is advantageously reduced. As further illustrated in FIG. 3 the contact means may be provided with locking tabs shown as protruding barbs 50 adapted to engage the inner surface of an electrically insulating support member 52 (See FIG. 4) within which the contact means may be lockingly engaged. Thus. the assembly comprising the support member 52 may be adapted to mate with a further insulated housing 54 as shown in FIG. 4 to provide a fully insulated electrical connector. The housing 54 may further more comprise a plurality of transverse openings adapted to coincide with the slots 32 of the contact means to provide access thereto as the contact means is disposed over and engaged with the associated conductors 38 inserted within the housing 54. To maintain the contact means in fixed position within an insulated housing such as 54 there may be further provided an additional locking means which may take the form of sharply pointed barbs such as 56 extending outwardly from either side of the contact means to engage the housing 54 as at 58 (FIG. 4) to prevent the withdrawal of the contact means therefrom. As further illustrated in detail in FIG. 5 the housing 54 may be provided with a transverse recess or pocket 60 adapted to receive the free ends of the leg portions of the contact means and may. alternatively, be effectively utilized to guide and limit the insertion of the assembly consisting of the support member 52 and the contact means within the housing 54.

To more fully appreciate the effect of the skew of each of the leg portions 26, reference is herein made to FIGS. 6 and 7. The solid outlines illustrated in these figures define the contour of the contact means 20 prior to engagement with the conductors 38, and the dotted outlines indicate the position of the various portions of the contact means 20 after engagement. As illustrated, each of the leg portions 26 is caused to pivotingly deflect substantially about its central longitudinal axis in response to the force exerted by the insertion of the conductors within the associated slots 28 in contact means 20. As illustrated in detail in FIG. 6, each of the leg portions 26. upon engagement with the conductors 38, is caused to be pivotingly deflected to the position indicated by the dotted outline 26'. Accordingly, the slot will tend to undergo a corresponding increase in width according to the conductor size and the degree of deflection of each of the leg portions 26, enabling the contact means to accommodate a relatively large range of conductor sizes without unduly stressing the base portion 24 or causing permanent deformation or fracture of the contact means. It should also be noted that the original pitch between adjacent leg portions is essentially undistrubed during and after conductor insertion. thereby increasing the reliability and permanency of the connection. The skew angle A shown in FIG. 7 as extending between the line 48 designating the plane of the base portion 24 and a line 62 representing the transverse axis of the leg portions 26 may be in the order of from approximately 5 to 15 degrees to effect the desired deflection. However, greater or lesser skew angles may be employed depending, for example, upon the deflection characteristics desired which, in turn, will be at least partially dependent upon such factors as the type of material from which the contact means is fabricated, the stock thickness, and the leg portion length to width ratio. The forces providing the pivoting action described heretofore are shown in detail in FIG. 7 and comprise an essentially normal force designated by the arrow 64 directed against the edge of the leg portion 26 in contact with the conductor 38. The force vector 64 may, by the employment of generally accepted mathematical principles, be divided into two component vectors, including a first vector indicated by the arrow 66 extending generally parallel to the axis 62, and a second vector indicated by the arrow 68 extending perpendicular to the vector 66. The force exerted on the leg portion 26 by the force indicated by the vector 68 will tend to twist or pivot the leg portion 26 about its longitudinal axis in the direction shown by the arrow 69 so that the final position of the leg portion 26 is substantially as indicated by the dotted outline 26'. It will also be noted that the force vector 68 on the left side of the central leg portion 26 illustrated in FIG. 7 denotes a force acting in a direction opposite to that indicated by the force vector 68 on the right side of the central leg portion 26 thus providing a dual force tending to develop a torque pivoting the leg portion 26 substantially about its axis B. It will, of course, be readily understood that a single conductor disposed within only one ofthe slots 26 will cause a similar action of the leg portion 26, but the torque to which the leg portion 26 is subjected will be approximately one half of that developed where conductors have been inserted within both slots flanking a particular leg portion 26. Although each of the leg portions 26 is shown as having an essentially undulating configuration in transverse section, such arrangement, although providing a relatively smooth transition from one leg portion to the next, may be modified as shown, for example. in FIG. 10 where there is illustrated a contact means 70 having essentially flat skewed leg portions 72 separated by slots 74 to provide a generally saw-tooth configuration functioning in a manner similar to the embodiments described hereinabove. The contact means 70, although shown as an essentially U-shaped member may, as described above with respect to the embodiment illustrated in FIG. 2, comprise simply a single row of leg portions 72, or alternatively may be formed of two or more separate elements suitably disposed in spaced parallel relationship to provide two or more rows of leg portions less a connecting portion 76 present in the U- shaped configuration illustrated in FIG. 10. As with the previously described embodiments, the slots 74 may either all be of the same or of differing widths, with either single or multiple zones, as set forth above. Thus, for example, the slots 74 indicated in the upper part of FIG. 10 may be narrower than the slots 74 indicated in the lower part of FIG. 10, so that, for example, the upper series of slots 74 may be designed to accept one particular range of conductor sizes while the lower series of slots 74 may be designed to accept a different range of conductor sizesv It will also be readily appreciated that the slots 74 may be suitably provided with any one of the contours described hereinabove or any combination thereof. according to the application and within the concepts herein disclosed.

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

l. Contact means for an electrical connector comprising: a metallic member formed from electrically conducting material and having a base portion and leg portions. said base portion being generally planar. said leg portions being bisected by a common plane and being integral with and extending from said base portion in generally spaced parallel relationship, there being a conductor receiving slot intermediate each two adjacent ones of said leg portions. said leg portions being skewed at a similar given angle about their re spective central longitudinal axes out of the plane of said base portion and planarly oriented substantially parallel to one another to cause the rotational displacement of each of said leg portions in a similar direction about its longitudinal axis upon engagement with a conductor inserted within an associated slot intermediate two adjacent ones of said leg portions.

2. Contact means as defined in claim 1 wherein each of said slots has a tapered entrance.

3. Contact means as defined in claim 1 wherein said metallic member comprises at least three leg portions.

4. Contact means as defined in claim 1 wherein each of said leg portions has a generally undulating configuration in transverse section.

5. Contact means as defined in claim 1 wherein each of said slots has a substantially uniform width throughout its length.

6. Contact means as defined in claim 1 wherein each of said slots comprises a conductor receiving zone having a given width. said conductor receiving zone communicating with a transition zone having a second given width. said second width being less than said first width.

7. Contact means as defined in claim 1 further comprising an insulated support member, said metallic member base portion being lockingly disposed within said support member.

8. Contact means as defined in claim 1 wherein said metallic member has a generally U-shaped configuration. and said leg portions are arranged in spaced opposing pairs.

9. Contact means as defined in claim 8 wherein said leg portions on one side of said U-shaped metallic member are all skewed at said similar given angle out of the plane of their associated base portion. and said leg portions on the remaining side of said u-shaped metallic member are all skewed at said similar given angle out of the plane of their associated base portion, said leg portions on said one side of said U-shaped member all being similarly angularly offset equally but oppositely from said leg portions on said remaining side of said U-shaped member in relation to an axis longitudinally bisecting said U-shaped member.

10. Contact means as defined in claim 9 wherein each of said leg portions has a generally undulating configuration in transverse section.

11. Contact means as defined in claim 9 wherein each of said slots has a substantially uniform width throughout its length.

12. Contact means as defined in claim 9 wherein each of said slots comprises a conductor receiving zone having a first given width. said conductor receiving zone communicating with a transition zone having a second given width, said second width being less than said first width.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,892,460

DATED July 1, 1975 |NVENTOR(S) Hyman Izraeli it is certified that eazor appears in the above-identified patent and that said Letters Patent are hereby corrected as shown beiow:

Column 1, line 19, delete "The sides of the slots defined by the edges of the blade members.

Signed and Scaled this [SEAL] Arrest:

C. MARSHALL DANN (mnmissiuner of Palenrs and Trademarks RUTH C. MASON Arresting Officer

Claims

1. Contact means for an electrical connector comprising: a metallic member formed from electrically conducting material and having a base portion and leg portions, said base portion being generally planar, said leg portions being bisected by a common plane and being integral with and extending from said base portion in generally spaced parallel relationship, there being a conductor receiving slot intermediate each two adjacent ones of said leg portions, said leg portions being skewed at a similar given angle about their respective central longitudinal axes out of the plane of said base portion and planarly oriented substantially parallel to one another to cause the rotational displacement of each of said leg portions in a similar direction about its longitudinal axis upon engagement with a conductor inserted within an associated slot intermediate two adjacent ones of said leg portions.

6. Contact means as defined in claim 1 wherein each of said slots comprises a conductor receiving zone having a given width, said conductor receiving zone communicating with a transition zone having a second given width, said second width being less than said first width.

8. Contact means as defined in claim 1 wherein said metallic member has a generally U-shaped configuration, and said leg portions are arranged in spaced opposing pairs.

9. Contact means as defined in claim 8 wherein said leg portions on one side of said U-shaped metallic member are all skewed at said similar given angle out of the plane of their associated base portion, and said leg portions on the remaining side of said u-shaped metallic member are all skewed at said similar given angle out of the plane of their associated base portion, said leg portions on said one side of said U-shaped member all being similarly angularly offset equally but oppositely from said leg portions on said remaining side of said U-shaped member in relation to an axis longitudinally bisecting said U-shaped member.

12. Contact means as defined in claim 9 wherein each of said slots comprises a conductor receiving zone having a first given width, said conductor receiving zone communicating with a transition zone having a second given width, said second width being less than said first width.