US3573714A

US3573714A - Electrical connector

Info

Publication number: US3573714A
Application number: US811107A
Authority: US
Inventors: Prescott K Turner
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1969-03-27
Filing date: 1969-03-27
Publication date: 1971-04-06
Anticipated expiration: 1988-04-06

Abstract

A connector, for an electric cord having at least two conductors enclosed in a jacket of noncircular cross section configuration, includes a body of electrical insulating material defining a passageway for entry of the cord into the connector. The passageway includes a first portion of cross-sectional size and shape complementary to an adjacent region of the cord jacket so as to intimately surround the adjacent region. The passageway also includes a second portion, outwardly of the first portion, which smoothly changes in cross-sectional shape from that of the first portion so as to approach a circular cross-sectional shape. There is a third portion, outwardly of the second portion, which is frustoconical in configuration.

Description

United States Patent FOREIGN PATENTS [72] Inventor Prescott K. Turner 21 A l N g i a g, C 268,961 6/1950 Switzerland 339 107 0. E 1 fg 27 1969 Primary Examiner-Richard E. Moore [45] Patented Apr. 6, Attorneys-John M Stoudt, Radford M. Reams, Jon C. {73 Assignee General Electric Company Gealow, Frank L. Neuhauser and Oscar B. Waddell 54] ELECTRICAL CONNECTOR ABSTRACT: A connector for an electric cord having at least two conductors enclosed in a acket of noncircular cross sec- Claims, 7 Drawing Figs.

tron configuration, includes a body of electrical insulating LS. Cl.

material defining a passageway for entry of the cord into the 339/107 connector. The passageway includes a first portion of cross- [51] Int. Cl H01r 13/56 ectional size and shape complementary to an adjacent region Fleld of Search t. of the cord jacket so as to intimately surround the adjacent re- 103-107, 101 gion. The passageway also includes a second portion, outwardly of the first portion, which smoothly changes in cross- [56] References cued sectional shape from that of the first portion so as to approach UNITED STATES PATENTS a circular cross-sectional shape. There is a third portion, out- 2,l92,737 3/ 1940 Folsom 339/107 wardly of the second portion, which is frustoconical in con- 3,3 35,394 8/1967 Miller 339/107 figuration.

54 '1j ii |ii y l9 4? i l I iul. l I i l R 46 $24 *6 g a I I ii A I I l 2! 32 33 37 60 Patented April 6, 1971 j 3,573,714

Inventor:

Presc .tt Tar/zen a M ELECTRICAL CONNECTOR BACKGROUND OF THE INVENTION The present invention relates to electrical connectors such as, for instance, appliance connectors.

Service cords, such as power cords for small appliances and general purpose extension cords are provided with connectors at either or both ends. Most of the small cords have connectors at both ends; one a male connector or plug for attachment to suitable outlet and one a female connector for connection to an appliance or other electrically energized device. During use, the portion of the cord emerging from the connector is very often subjected to repeated bending and twisting forces. Such bending and twisting can eventually cause one or more of the conductors in the cord to fail. This usually occurs because of breakage of a number of the individual strands or wire which have been wound together to form the conductor.

Prior-art arrangements for preventing such failures, resulting from twisting and bending, have not been completely satisfactory. Some arrangements unduly restrict the selection of connector material, others provide assemblies which are excessively large and heavy for the contemplated use and others result in connectors which are too susceptible to breakage.

SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide a new and improved connector.

It is another object of this invention to provide such an improved connector which minimizes the adverse effect of twisting and bending an associated electrical cord.

It is a further object of this invention to provide such a connector which biases the associated cord for twisting in the direction to tighten the helix of the conductors.

The invention, in one form thereof, provides a connector for an electrical cord having at least two conductors enclosed in a jacket of noncircular cross section configuration having a major and a minor axis. The connector comprises a body of insulating material defining a passageway for entry of the cord into the connector. The passageway includes a first portion of cross-sectional shape and size complementary to an adjacent region of the cord jacket so as to intimately surround the adjacent region. The passageway further includes a second portion extending outwardly from the first portion. The cross-sectional shape of the second portion smoothly changes in the outward direction from the cross-sectional shape of the first portion so as to approach a circular cross-sectional shape.

The above-mentioned and other features and objects of this invention, as well as the manner of attaining them will become more apparent, and the invention itself will be better understood by reference to the following description, taken in conjunction with the accompanying drawing, wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a plan view of a connector incorporating one embodiment of the present invention;

FIG. 2 is an enlarged plan view of the two body sections of the connector of FIG. 1, with the body sections disconnected to show the inside of each and with the associated electric cord and contacts removed;

FIG. 3 is an enlarged end view of the connector of FIG. 1, showing the cord entry portion ofthe connector;

FIG. 4 is a view taken along line 4-4 of FIG. 3;

FIG. Sis a view taken along line 5-5 of FIG. 3;

FIG. 6 is a view similar to FIG. 4, but with the cord removed; and

FIG. 7 is a view similar to FIG. 5, but with the cord removed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing, particularly FIG. I, there is shown an electrical connector 10 for use with an electrical cord 1 I. More particularly the exemplification connector 10 is a small female connector of the type used with appliance power cords. The cord 11 is of the type having two electrical connectors enclosed in a jacket of flexible material which is noncircular in cross section, the exemplification being a cord having two conductors l2 and 13 which are arranged in parallel, side-by-side configuration.

Referring more particularly to FIGS. 3 through 5 it will be seen that the conductors l2 and 13 each are formed from a plurality of small, individual wires or strands which are spirally wound. The conductors are enclosed in a jacket 14 of flexible electrically insulating material. The cross-sectional shape of the cord is noncircular, having a major and a minor axis. The major axis extends through the two

conductors

12 and 13, while the minor axis is transverse thereto. The outer surface of the jacket may also be said to have a plurality of discrete surfaces. For instance, the semicircular arcs at the ends of the major axis are a one set of opposed convexedly curved surfaces, with the surfaces joining them between the conductors being another set of opposed surfaces.

Referring now to FIGS. 1 and 2, the connector 10 comprises a body of electrically insulating material such as of phenolic resin and is formed as two separate body sections or halves I5 and I6, which are secured together to form the connector body. Body section 15 is formed with a pair of parallel, longitudinal extending

recesses

17 and 18, separated by a wall 19; body section 16 is formed with a pair of parallel, longitudinally extending

recesses

20 and 21, separated by a wall 22. When the body sections are joined, the

recesses

17 and 21, the

walls

19 and 22 and the

recesses

18 and 20 respectively are all brought into register to form a pair of contact receiving recesses separated by a wall of insulating material. The longitudinal axes of these contact receiving recesses define a plane.

The wall 19 includes an outwardly extending stub shaft 23 and the wall 22 includes corresponding recess 24 so that, when the body sections are placed together or joined, the stub shaft 23 is received in the recess 24 to properly align the two halves. The

walls

19 and 22 also have aligned

openings

25 and 26 which extend completely through the respective body sections so that a rivet 27 may be mounted therein to securely join together the body sections. Body section 15 includes partitions 28 and 29, which extend across the

recesses

17 and 18 respectively. Similarly, the body section 16 has a pair of spaced

partitions

30 and 31 which extend across the recess 20, and a pair of spaced

partitions

32 and 33 which extend across the recess 21. These partitions 28-33 cooperate to form a strain relief for the conductor which is attached to the contacts received in the contact-receiving recesses. A more complete description of such a strain relief may be had by reference to applicanta copending application, Ser. No. 811,057 filed Mar. 27, I969 which is assigned to General Electric Company, assignee of the present invention.

Body section 15 includes a pair of posts 34 and 35 which are received in

corresponding recess portions

36 and 37 of body section 16, to assist the shaft 23 and recess 24in properly aligning the body sections upon joining and to absorb forces generated by the strain relief. Each body section includes a mating surface, 38 and 39 respectively, which abut when the two sections are joined to form the connector 10. Their juncture forms the parting line 40 of the connector. In the exemplification the parting line 40 lies in the plane defined by the axes of the contact-receiving recesses. It will be understood that the sections could be given other configurations in which this is not the case. However, for ease of assembly, it is desirable to make the sections somewhat symmetrical.

The end portion of each of the body halves I5 and 16, remote from the contact-receiving recesses, is formed with a recess, 41 and 42 respectively. These recesses are positioned so as to be aligned when the sections are joined to form a passageway 43 to receive the electrical cord as it extends away from the contacts and out of the connector. The body section 15 includes an arcuate wall portion 44 and an arcuate wall portion 45 while the body section 16 includes similar

arcuate wall portions

46 and 47. When the two body sections are joined, the wall portions 44 and 47 come into register to form a first concavely curved lateral surface 48 for the passageway 43 while the

arcuate wall portions

45 and 46 come into register to form a second concavely lateral surface 49. The lateral surfaces 48 and 49 are disposed on diametrically op posite sides of the passageway 43.

Adjacent the inner end of recess 41, the body section 15 includes a flat wall surface 50, which extends in a direction parallel to the axis of the passageway 43. Similarly the body section 16 includes a flat surface 51 which extends generally parallel to the axis of passageway 43. The

surfaces

50 and 51 are disposed on diametrically opposite sides of the passageway 43 and interconnect with the axially inner portions of the curved lateral surfaces 48 and 49 to form a first portion of the passageway 43. This first portion of the passageway has a size and shape complementary to an adjacent region of the cord so as to intimately surround the adjacent region. More specifcally the first portionof the passageway includes a first pair of spaced, oppositely disposed

lateral surfaces

48 and 49 having concavely curved cross sections and a second pair of spaced, oppositely disposed

lateral surfaces

50 and 51 joining the first pa|r.

Extending outwardly from the flat surface 50 the body section 15 is formed with a second flat surface 52. Similarly the body section 16 is formed with a flat surface 53 while extending outwardly from the flat surface 51. These

surfaces

53 and 52 are disposed on opposite sides of the passageway 43 and, with the adjacent portions of the lateral surfaces 48 and 49, form a second portion of the passageway 43. The flat surfaces 52 and 53 are mutually divergent in the axially outward direction, as best seen in FIGS. and 7. That is, the further out the passageway, the further apart are the

surfaces

52 and 53. Also, the further out the second portion of the passageway, the larger the arc and radius of each of the concavely curved

lateral surface

48 and 49. This results in the

flat surfaces

52 and 53 having an ever decreasing width outwardly along the passageway.

Axially outwardly of the

surfaces

44, 45 and 52, the body section is provided with a uniformly divergent surface 54 while, axially outwardly of the

surfaces

46, 47 and 53 the body section 16 is formed with a similarly divergent surface 55. These two surfaces 54 and 55 come into register, when the body sections are joined, to form a third portion of the passageway 43, axially outwardly of the second portion. This third portion is frustoconical in shape. It will be seen from FIGS. 2, 3 and 6 that the second wall portion merges into the third wall portion before or just as the concavely curved lateral surfaces 48 and 49 increase in are sufficiently to join. That is, the second portion of the passageway changes smoothly from the cross section of the first portion toward a circular cross section. In 60, exemplification, the second portion does not quite reach a circular cross section; however, it may just form a circular cross section if desired.

At the outer ends of the wall portions 54 and 55 the body halves 15 and 16 are provided with

external walls

57 and 58 which slant back toward the other end of the connector and terminate in

rib portions

59 and 60, respectively. The

rib portions

59 and 60 join to form the rib 61 for the user to grasp in manipulating the connector.

As best seen in FIGS. 3 and 5, the first portion of the passageway 43,- that is the portion formed by

surfaces

50 and 51 and the adjacent portions of

surfaces

48 and 49, intimately surrounds the adjacent region of the electrical cord. This prevents any substantial lateral movement of the cord relative to the passageway, including twisting, at that position and establishes a reference disposition of the cord.

It will be seen from FIG. 5, that, as the cord is, bent, it will engage the connector at least at the junction 62 between the first and second portions ofthe passageway, at the junction 63 between the second and third portions of the passageway and at the outer edge 64 of the passageway. Applicant has found that the minimum three-point contract between the cord and connector, resulting from the three differently shaped portions of the passageway, establishes a smooth curve in the cord as it is bent. Thus it is not necessary to curve all of the cord entry passageway wall in order to prevent sharp bends in an associated cord. In fact the construction of the exemplification gives longer flexing life than a similar construction having a convexly curved third portion rather than the frustoconical third portion.

During use the cord quite often will be twisted with respect to the connector, sometimes as much as When this occurs the twist in cord tend to occur as it enters the connector. If the cord is allowed to twist sharply at one point, the repeated twists will tend to break the individual wires forming the conductors causing electrical failure of the cord. As an important aspect of this invention the shape of the passageway will distribute this twist over the discrete length or portion of the cord and prevent the cord twisting sharply at any one location. To this end, in the first portion of the passageway the

surfaces

48 and 49 are spaced apart just slightly more than the width of the cord 11, across its major axis. Also the arcs and radii of these surfaces increase in the axially outward direction. The

surfaces

52 and 53 are mutually divergent in the axially outward direction along the passageway. This forms a smoothly curving intersections between the

surfaces

48 and 49 and the

surfaces

52 and 53. These intersections limit the twist of the cord and distribute it along the second passageway portion, thus preventing a sharp twist at any one point.

As the cord is bent essentially over the

surfaces

52 or 53, that is up or down as seen in FIG. 3, there will be essentially no twist to the cord. However, if the cord is bent so as to move outwardly over either of the

curved surfaces

48 and 49, that is to the right or left in FIG. 3, the cord will twist as well as bend. The interrelationship of surfaces forming the second or intermediate portion of the cord entry passageway, together with the first or inner portion of the passageway, distributes this twist of the cord into a controlled helical form along the second passageway portion and prevents it from occuring as a tight twist in the cord, which could cause failure.

Many electrical cords used with connectors of this general type are formed with each of the conductors made of a large number of small wires which are wound together in a helical manner. In such conductors the helix of all the conductors is the same. It will be understood that such conductors may be twisted a small amount either with or against the helix of the wound wires without undue damage to the cord. However, it situations where there is substantial twisting coupled with a pulling force, the direction of the twist makes a great deal of difference. Such insulated conductors may be twisted in the direction of the helix, that is tending to tighten the helix of the conductor repeatedly without any particular damage as the strands are already tightly wound on each other. On the other hand, if the insulated stranded conductor is twisted in the direction against the helix, that is in a direction tending to loosen and flex the individual strands, fatigue of the strands and damage to the conductor tends to occur much quicker. This is particularly true when the twisting is accomplished by a bending of the conductor.

As explained above, there is no substantial twisting of the conductors if the cord is bent up or down, as seen in FIG. 3, but, when the cord is bent to the right or left, as seen in FIG. 3, the bending is accompanied by a twisting of the cord. The twisting of the cord is transmitted to the individual conductors l2 and 13.

As an important aspect of the invention the

flat surfaces

50, 51, 52 and 53 are offset so that the major axis of the passageway 43, and thus the major axis of the cord as it enters the connector, is offset a small angle with respect to plane established by the contact-receiving recesses. More specifically the major axis of the passageway 43 is offset or rotated in the direction tending to tighten the helix of the individual strands in the

conductors

12 and 13. This angle normally will not exceed 45 and about 30 has been found to give very good results. This rotation of the passageway with respect to the plane of the contact recesses biases the cord 11 so that it tends to twist in the direction ,to tighten the helix of the individual conductors l2 and 13 as the wire is pulled to the right or the left, as seen in FIG. 3. These are the directions involving substantial twisting of the individual wires in the conductors l2 and 13 and they are being tightened then rather than being loosened. If the cord is bent upwardly or downwardly as seen in FIG. 3, there may be some slight twisting in a direction to loosen the wires or strand; however the amount of the twist is so slight as to have very little effect if any detrimental effect on the cord life.

lclaim:

1. A connector for assembly comprising: an electrical cord having at least two conductors enclosed in a jacket of noncircular cross section configuration having a major and a minor axis; a connector body of insulating material defining a passageway for entry of said cord into said connector body; said passageway including a first portion of cross-sectional shape and size complementary to an adjacent region of said cord jacket and intimately surrounding said adjacent region; said passageway furtherincluding a second portion extending outwardly from said first portion, the cross-sectional shape of said second portion" smoothly changing in the outward direction from the cross-sectional shape of said first portion so as to approach a circular cross-sectional shape.

2.The connector assembly as set forth in claim 1, wherein said second portion of said passageway has a major and a minor axis and said minor axis lengthens in the outward direction.

3. The connector assembly as set forth in claim 1, wherein said passageway includes a third portion outwardly of said second portion, said third portion being of a generally frustoconical configuration divergent in the outward direction.

4. A connector assembly comprising: an electrical cord having at least two conductors enclosed in a jacket of noncircular cross section configuration, said jacket having a plurality of discrete lateral surfaces; a connector body of insulating material defining a passageway for entry of said cord into said connector body, said passageway including a first portion having discrete lateral surfaces corresponding to and intimately surrounding said lateral surfaces of an adjacent region of said cord jacket; said passageway further including a second portion extending outwardly from said first portion; the lateral wall of said second portion smoothly changing in the outward direction from the discrete lateral surfaces of said first portion so as to approach a circular cross-sectional shape.

5. The connector assembly as set forth in claim 4, wherein said passageway includes a third portion outwardly of said second portion, said third portion being of generally frustoconical configuration divergent direction.

6. The connector assembly as set forth in claim 4, wherein said passageway includes a first pair of spaced, oppositely disposed lateral surfaces having concavely curved cross sections and a second pair of spaced, oppositely disposed lateral surfaces joining said first pair of lateral surfaces; said first pair of lateral surfaces being of increasing arcs in the outward direction across said second portion of said passageway and said second pair of lateral surfaces being mutually divergent across said second portion of said passageway.

7. The connector assembly as set forth in claim 6, wherein said passageway includes a third portion outwardly of said second portion, said third portion being of a generally frustoconical configuration divergent in the outward direction.

8. A connector assembly comprising: an electrical cord having at least two conductors enclosed in a jacket of noncircular cross section configuration having a major and a minor axis, each conductor being formed ofa plurality of helically wound strands with the helix of both conductors being in the same direction; a contact attached to each of said conductors; a

connector bod of insulating material defining a pair of laterally-space recesses, each recess receiving a corresponding one of said contacts; the axes of said contact-receiving recesses defining a plane; said connector body further defining passageway receiving said cord as it extends from the contacts out of said connector body; said passageway including a first portion of cross-sectional shape and size complementary to an adjacent region of the cord jacket so as to intimately surround the adjacent region; the major axis of said first portion of said passageway being rotated a relatively small angle from the plane of said contact-receiving recesses in the direction tending to tighten the helix of said conductors; said passageway further including a second portion of the side of said first portion remote from said contact-receiving recesses; the crosssectional shape of said second portion smoothly changing, in the direction away from said contact-receiving recesses, from the cross-sectional shape of said first portion so as to approach a circular cross-sectional shape.

9. The connector assembly as set forth in claim 8, wherein said second portion of said passageway has a major and a minor axis and said minor axis lengthens in the outward direction.

10. The connector assembly as set forth in claim 9, wherein said passageway includes a third portion and the side of said second portion remote from said first portion, said third portion being of a generally frustoconical configuration divergent in the direction away from said second section.

in the outward

Claims

1. A connector for assembly comprising: an electrical cord having at least two conductors enclosed in a jacket of noncircular cross section configuration having a major and a minor axis; a connector body of insulating material defining a passageway for entry of said cord into said connector body; said passageway including a first portion of cross-sectional shape and size complementary to an adjacent region of said cord jacket and intimately surrounding said adjacent region; said passageway further including a second portion extending outwardly from said first portion, the cross-sectional shape of said second portion smoothly changing in the outward direction from the crosssectional shape of said first portion so as to approach a circular cross-sectional shape.

2. The connector assembly as set forth in claim 1, wherein said second portion of said passageway has a major and a minor axis and said minor axis lengthens in the outward direction.

5. The connector assembly as set forth in claim 4, wherein said passageway includes a third portion outwardly of said second portion, said third portion being of generally frustoconical configuration divergent in the outward direction.

8. A connector assembly comprising: an electrical cord having at least two conductors enclosed in a jacket of noncircular cross section configuration having a major and a minor axis, each conductor being formed of a plurality of helically wound strands with the helix of both conductors being in the same direction; a contact attached to each of said conductors; a connector body of insulating material defining a pair of laterally-spaced recesses, each recess receiving a corresponding one of said contacts; the axes of said contact-receiving recesses defining a plane; said connector body further defining passageway receiving said cord as it extends from the contacts out of said connector body; said passageway including a first portion of cross-sectional shape and size complementary to an adjacent region of the cord jacket so as to intimately surround the adjacent region; the major axis of said first portion of said passageway being rotated a relatively small angle from the plane of said contact-receiving recesses in the direction tending to tighten the helix of said conductors; said passageway further including a second portion of the side of said first portion remote from said contact-receiving recesses; the cross-sectional shape of said second portion smoothly changing, in the direction away from said contact-receiving recesses, from the cross-sectional shape of said first portion so as to approach a circular cross-sectional shape.