US2993189A - Polarized connector - Google Patents

Description

July 18, 1961 R. K. SCHELKE ETAL POLARIZED CONNECTOR Filed March 10, 1958 2,993,189 POLARIZED CONNECTOR Robert K. Schelke, Richmond, Ind, and James D. Priest, New Paris, Ohio, assignors to Belden Manufacturing Company, Chicago, 111., a corporation of Illinois Filed Mar. 10, 1958, Ser. No. 720,373 Claims. (Cl. 3'39-59) This invention relates generally to electrical connectors and more particularly to polarized electrical connectors.

Due to the complicated and sensitive circuitry commonly involved and to the higher electrical currents frequently employed, many of the electrical and electronic devices of today require the making of electrical connections between the device and a source of power, or between the various separate units of a multi-unit device, in such a fashion as to insure that only the proper associated terminals are allowed to be brought into contact with one another in order to prevent the possibility of starting a fire within the device or causing intricate and delicate operating components to be broken or otherwise rendered inoperative.

To meet this requirement, complementary polarized plugs and connectors were developed in which a plurality of associated contacts are arranged to preclude the insertion of the plug in the connector except in one predetermined operating position. In this position, contact is made within the connector between the proper female and male contacts.

Recognizing the harm that might result from the contacting of non-associated terminals, the bodies of the connectors have been manufactured in the past from a relatively rigid material, such as hard rubber or Bakelite, which is adapted to prevent the forceable insertion of a non-associated male contact within one of the openings in the conductor and resultant contact with a non-associated female contact.

Consequently, connectors made in this fashion have been relatively expensive due to the material employed in fabricating the body and/or quite brittle, and therefore subject to being cracked or broken if dropped accidently on a hard surface or if too great a force is applied in attempting to force entry of a non-associated male contact within the connector.

Accordingly, the present invention is primarily directed to the elimination and/or reduction of these disadvantages, as well as others, and has for its principal object the provision of a new and improved polarized connector which has improved wearability characteristics and which is of less expensive construction than has heretofore been employed. A further object of the present invention is the provision of a polarized connector, of the type described, which is adapted for use with a complementary polarized male plug or with a conventional non-polarized male plug, and which has a body portion of relatively soft dielectric material provided with suitable means for precluding the entrance of a complementary polarized male plug in misorientation, a non-complementary polarized male plug, or a male contact in misorientation or having a greater cross sectional dimension than that of the entrance opening. Other objects and advantages of the present invention will be understood by reference to the following description and to the accompanying drawings of one selected embodiment.

In the drawings:

FIGURE 1 is a perspective View of a connector embodying various of the features of the present invention, and illustrating one of the barriers in the partially inserted position;

FIGURE 2 is a partially broken away and cross sectioned end view of the connector shown in FIGURE 1;

Patented July 18, 1961 ice FIGURE 3 is a perspective view of a barrier employed in the present invention;

FIGURE 4 is a cross sectional view taken along line 44 of FIGURE 2;

FIGURE 5 is a cross sectional view taken along line 55 of FIGURE 2;

FIGURE 6 is a partially broken away and cross sectioned end view illustrating a modified connector; and

FIGURE 7 is a side elevational view of the modified connector shown in FIGURE 6.

Illustrated generally in FIGURE 1 is one selected embodiment of a polarized connector disposed about the end of an electrical cord and intended for use with a complementary male plug. The illustrated connector embodies various of the features of the present invention, is generally referred to in the electrical industry as a Nema connector, and is suitably designed and dimensioned to conform to the standards relating to connectors as published by Underwriters Laboratories, Inc. As will be more fully described, the female connector includes a relatively soft dielectric body or housing 11, having an end or face 19, and a plurality of bores or openings 13, 15 and 17 which extend from the interior female contacts (not shown in FIGURE 1) and through which access may be had between the interior female contacts and the respectively associated contacts of a complementary polarized male plug. Extending within the body 11 and around the bore 15, is a barrier or insert 21 of relatively rigid dielectric material. A similar barrier 23 is provided to surround the bore 15 and is shown in FIG- URE 1 in a partially inserted position. Each of the barriers 21 and 243 is suitably provided with an opening or passage 25 and 27, respectively, which is positioned in register with respective bores 13 and 15 and which is adapted by reason of its rigid form to resist forceable entry of a non-associated male contact having a cross sectional dimension greater than that of the passage or opening contained therein. In this fashion, a complementary polarized male plug may be inserted within the connector in only one predetermined proper operational position. Insertion of the complementary polarized plug in any other incorrect position is precluded by the action of the barriers 21 and 23.

The connector disclosed herein is designed to receive a complementary polarized male plug having three male contacts, including an arcuate grounding prong and a pair of parallel, spaced apart rectangular blades which are of equal thickness but of slightly different widths. However, the disclosed connector is also designed for use with a conventional non-polarized male plug. In this respect, the spacing contemplated between the parallel blades of the complementary polarized plug is identical to the spacing employed between the twin blades of the conventional non-polarized plug, and the contemplated size of the smaller polarized rectangular blade is at least as large as the twin blades of the conventional plug. In this fashion, the blades of the conventional male plug which may be of lesser width than the polarized blades, will readily pass through the barriers. In addition, the disclosed connector is adapted to receive a polarized male plug having an arcuate grounding prong and a pair of twin rectangular blades of similar design to that employed in the conventional non-polarized male plug.

Although the present invention has been briefly described, and will be more fully described, in terms of the connector illustrated in FIGURE 1, it should be immediately apparent that this invention is applicable to numerous variations in the number and arrangements of contacts employed. In this connection, the female connector may be constructed to receive 2, 3, 4 or more male contacts in various different patterns or arrangement. In addition, the connector may provide for the receipt of male contacts of a Wide variety of different cross sections as may seem most desirable under the circumstances. Moreover, it may be desirable or sufiicient to provide a barrier for just one of the female contacts, or it may seem more preferable, depending upon the installation, to provide barriers for all of the contacts or for any intermediate number of contacts.

To achieve the greatest advantage of this invention, the body 11 of the connector is preferably of a relatively soft and resilient dielectric material, which may be readily and economically formed or molded, such as a thermoplastic resin. The body may take a Wide variety of shapes and forms, taking into consideration the various requirements of manufacturing techniques to be employed, the number and size of the female contacts to be used, the decorative exterior design desired, and any type of ribbing or means for assisting in grasping the connector during the joining and disconnecting of the connector to a complementary plug. In this instance, the body takes the form illustrated in FIGURE 1, and is of generally pentagonal cross section having a fiat outer end or face 19 from which the sides of the connector extend in generally perpendicular relation and subsequently converge to form the other end from which the cord 29 extends. Various of the sides are formed with a series of ribs 31 to assist in grasping the connector, as heretofore mentioned.

In this embodiment, there are embedded during the molding of the connector body 11, three female contact members 33, 35 and 37 (as shown in FIGURES 4 and positioned in substantially perpendicular relation with respect to the face 19. The contacts 33 and 35 are located in opposed relation to each other as shown, while the third contact 37 is located in spaced relation from adjacent sides of each of the contacts 33 and 35. and is in general alignment with an imaginary line running parallel to and centrally of the contacts 33 and 35.

The two female contacts 33 and 35 are of similar consiruction and are each intended to receive one of a pair of male contacts which are of generally rectangular cross section. Briefly, each of the female contacts 33 and 35 includes a jaw section 39 at one end adapted to receive and make contact with the associated male contact, a section 41 at the other end having a pair of ears 43 adapted to crimp the respective lead wires to the contacts, and an intermediate retroverted ear 45 for maintaining the base region of the opposing jaws in closely adjacent relation.

The other female contact 3'7 is intended to receive a grounded male contact having a generally arcuate cross section. This contact 37 includes a tubular section 47 for receiving the associated male contact, a section 49 for crimping the ground lead wire to the contact.

In order for the female contacts of the connector to receive the associated male contacts of the complementary plug, the series of openings or bores 13, 15 and 17 are provided, as before noted, which are in general alignment with the respective female contacts 33, 35 and 37, and which are therefore in substantially perpendicular relation to the face 19. Each of the openings 13 and 15 is formed with a cross section slightly larger than the cross section of the associated contact of the complementary polarized male plug. In this case, the openings 13 and 15, which lead to the respective female contacts 33 and 35, are of generally rectangular cross section and are preferably beveled at their outer extremity to provide for greater ease in locating and joining the male plug to the female connector. The cross section of the opening 17 conforms generally to the open cross section of the tubular receiving section 47 of the female contact 37.

As the connector body 11 of this embodiment is made of relatively soft and resilient dielectric material, the bores or openings 13, 15 and 17 are susceptible to deformation under pressure to allow the forceable insertion of non-associated male contacts. To remedy this situation, the barriers 21 and 23 of relatively rigid dielectric material are provided about the respective openings 13 and 15 to prevent the forceable insertion of nonassociated male contacts. However, if desired, all of the openings of the connector may be protected by barriers, or only one of the openings may be so protected. Furthermore, while a single barrier piece might be employed to shield more than one opening, it is desirable to provide individual barriers for each of the openings. It has been found in the past that it is considerably more difficult to accurately align the openings in a single barrier piece with the body openings leading to the female contacts than it is to align each of the openings of a multiplicity of individual barriers with the respective body openings. Furthermore, the use of a single barrier piece, particularly under moist conditions, may provide a path for allowing electrical tracking between the contacts included within the body of the connector.

It has been found most desirable for manufacturing and economic reasons to provide the desired rigidity adjacent the entrance of the body openings by the forceable insertion of the preferred number of barriers within the resilient connector body. Accordingly, although other means for fabricating or constructing the connector body with suitable protection against incorrect entry may be employed, the barriers and the housing in this embodiment have been designed with this feature in mind. In the embodiment illustrated, each of the rectangular openings 13 and 15, by which access maybe had to the female contacts 33 and 35, is provided with a barrier 21 and 23 respectively. To accommodate the barriers 21 and 23, a cavity 53 and 55 is provided surrounding each of the respective bores 13 and 15 intermediate the face 19 and the respective female contacts. Each of the cavities 53 and 55 is formed with a main portion 57 which surrounds the respective openings 13 and 15, and a neck portion 59 of lesser cross sectional area which extends from the main portion 57 to an adjacent exterior side of the connector body 11. Generally, each of the cavities is proportioned to correspond with the outer dimensions of the respective barriers.

Each of the barriers 21 and 23, as before noted, is fabricated from relatively rigid dielectric material such as by stamping from a paper base phenolic sheet and is provided with a respective opening or passage 25 and 27 which is of substantially the same size as the associated body opening and which is in register with the associated body opening when the barrier is properly inserted within the respective cavity of the connector body. The open rings 25 and 27 in the relatively rigid barriers 21' and 23 preclude the forceable entry within the relatively soft connector body of a complementary male plug in misorientation, a non-complementary polarized male plug, a male contact which is out of alignment with the connector opening in which insertion is being attempted, or a non-associated male contact having a larger corresponding cross sectional dimension.

While the barriers 21 and 23 may be formed in various suitable shapes to accommodate the desired preclusion of non-associated malecontacts, in this preferred illus' trated embodiment, each of the barriers 21 and 23 com prises a main section 61 and a neck section 63. The neck section 63 is of somewhat lesser cross section to provide a shoulder 65 which is adapted to maintain the barrier within the connector body 11 after having been properly inserted therein. The outer end 67 of the neck section 63 is formed at an angle to conform with the exterior surface of the molded body 11 and to thereby provide a continuously smooth surface. The main section 61 of each of the barriers 21 and 23 is provided with the respective desired opening 25 or 27 and is of generally rectangular form except that each of the sides adjacent the inner end of the barriers is tapered, as indicated at 69, to assist in insertion of the barriers within the molded body. In addition, the openings 25 and 27 in the barriers 21 and 23 are of generally rectangular form but differ from one another dimensionally in accordance with the dimensions of the associated contacts of the complementary polarized male plug which are intended to be received by the respective female contact members.

With respect to the insertion of the barriers 21 and 23 within the connector body 11, it will be noted that, in this embodiment, the body 11 is constructed of a soft and resilient material which permits the necessary deformation to allow insertion of the barriers 21 and 23, and which, at the same time, provides for the reassumption of the original body contour to thereby maintain the barriers 21 and 23 in proper location within the body 11.

Barriers of different sizes may be readily color coded for identification purposes. This feature is useful in the manufacturing process as it simplifies the selection of the proper barrier for insertion within a particular cavity in a particular connector. Furthermore, the colored inserts may serve to identify which of the female contacts in a connector are to be connected to certain male prongs. This is of particular utility if one connector is to be employed with a plurality of male plugs each having a unitary prong.

In addition, it will be observed that if the disclosed connector is joined with a male plug having an arcuate grounding prong and a pair of twin rectangular blades, of equal size, as before mentioned, it is possible to insert the rectangular blades in reversed order to thereby connect the male contacts to the inappropriate female contact members. In this situation, the grounding prong would extend exterior to the connector in adjacent relation to the side of the connector in the area indicated by the numeral 75 in FIGURE 1. This possibility can be prevented by forming the housing 11, as shown in FIG- URES 6 and 7, with an integral boss or shoulder indicated by the numeral 77. In this regard, in order to insure preclusion of the entrance of the pair of male rectangular blades in reverse order within the female connector, the boss 77 is located, with respect to the female contact members 33 and 35, in diametrically opposed relation to the female contact member 37. Thusly, the boss 77 extends outwardly from the connector body proper a suitable distance to assure blocking of the grounding prong, and in addition, extends longitudinally from adjacent the face 19 for a sufficient length to provide adequate structural strength. Consequently, by the use of the described boss, the insertion in reversed order of the twin male contact blades Within the connector body and resultant inappropriate contact with the female contact members is effectively prevented.

A polarized connector embodying various of the features of the present invention in which a plurality of female contacts are arranged and embedded in a relatively soft and resilient dielectric body and in which relatively rigid barriers have been inserted about the openings leading to the female contacts, provides the advantages of permitting the use of economical materials in the construction of the connector, while at the same time, provides for decreased brittleness, resultant improved wearability characteristics, and effective preclusion of the entry of non-associated rnale contacts or the joining in misorientation of a complementary polarized male plug and female connector.

Other additional changes and modifications may be made in the disclosed construction to achieve certain of the features mentioned herein without departing from the principles of the present invention.

We claim:

1. A polarized female electrical connector comprising a relatively soft dielectric body having an end face and a side face, first and second female contact members located within said body for receipt of associated first and second male contacts extending from a complementary male plug, said body having first and second openings therein extending from said end face respectively to said first and second female contact members for providing access to said female contact members by the associated male contacts, the first male contact having a smaller cross sectional dimension than the second male contact, said body having a cavity extending inwardly from said side face in spaced relation to said end face and in surrounding relation to the first opening, and a relatively rigid dielectric barrier located Within and fixedly held within said cavity, said barrier being substantially larger than the first opening so that said barrier is unremovable through said opening, said barrier having a passage therein in alignment with said first opening to permit connection between said first female contact memher and said first male contact and to preclude connection between said first female contact member and said second male contact.

2. A polarized female electrical connector comprising a relatively soft dielectric body having an end face and a side face, first and second female contact members located within said body for receipt of associated first and second male contacts extending from a complementary male plug, said body having first and second openings extending from said end face of said body respectively to said first and second female contact members for providing access to said female contact members by the associated male contacts, the first male contact having a smaller cross sectional dimension than the second male contact, said body having a cavity extending inwardly from said side face in spaced relation to said end face and in surrounding relation to the first opening, and a relatively rigid, flat dielectric barrier inserted in and fixedly held within said cavity, said barrier being substantially larger than said opening so that said barrier is unrernovable through said opening, said barrier having a passage therein which is aligned with said first body opening and is slightly larger than said first male contact but smaller than said second male contact, thereby permitting connection between said first female contact member and said first male contact and precluding the connection between said first female contact member and said second male contact.

3. A polarized female electrical connector disposed around the end of an electrical cord for use with a com plementary male plug having a like number and arrangement of male contacts, said polarized connector comprising a molded dielectric body of relatively soft and resilient material having an end face and a side face, first and second female contact members embedded within said body for receipt of associated first and second male contacts, the first male contact having a smaller cross sectional dimension than the second male contact, said first and second female contact members being respec/ tively accessible within said body through first and second openings in said body extending from said female contact members to said end face, said openings being in general alignment with said female contact members, being generally perpendicular to said end face, and being slightly larger in cross section than the associated male contacts, said molded body being formed with a cavity spaced from said end face, said cavity having a main portion extending generally transversely of and circumferentially about said first opening and having a neck portion of lesser cross section extending from said main portion to said side face of said body, and a barrier of relatively rigid dielectric material inserted within the cavity through the neck portion, the barrier being provided at its inner end with a tapered side edge to assist in insertion of the barrier Within the cavity and being provided adjacent the outer end thereof with a shoulder adapted to abut against the interior of the neck portion of the cavity to prevent outward displacement of the barrier from the cavity, the barrier having a passage therein in alignment with the first body opening, the passage being slightly 7 larger than said first male contact but smaller than said second male contact, thereby preventing said second male contact from passing through the first opening and contacting the first female contact member.

4. A polarized female electrical connector disposed around the end of an electrical cord for use with a con1- plementary male plug having a like number and arrangement of male contacts, said polarized connector comprising a dielectric body having an end face and a plurality of sides extending therefrom, a plurality of female contact members embedded in said body in longitudinal parallel relationship including first and second spaced apart, generally identical female contact members disposed in said body so that a plane bisecting both said first and second female contact members extends generally parallel to one of said sides of said body, said first and second female contact members being disposed in parallel orientation to one another for receipt of associated first and second male contacts extending from the complementary plug, and a third female contact member spaced from one side of said plane a distance greater than the distance from the opposite side of said plane to said one side of said body for receiving an associated male prong extending from the complementary plug, said female contact members being respectively accessible within said body through aligned openings in said body extending fro-m said female contact members to said one face, said body having a shoulder on said one side located adjacent said end face and on a line which extends perpendicular to said plane and through the third female contact member, whereby said shoulder blocks the travel of the male prong and thereby prevents insertion of the first and second rnale contacts in misassociation with the first and second female con-tact members.

5. A polarized female electrical connector disposed around the end of an electrical cord for use with a complementary male plug having a like number and arrangement of male contacts, said polarized connector comprising a resilient dielectric body heaving an end face and a plurality of side faces extending therefrom, a plurality of female contact members embedded in said body in longitudinal parallel relationship including first and second spaced apart generally identical female contact members disposed in said body so that a plane bisecting both of said first and second female contact members extends generally parallel to one of said side faces of said body, said first and second female contact members being disposed in parallel orientation to one another for receipt of associated first and second male contacts extending from the complementary plug, and a third female contact member spaced from one side of said plane a distance greater than that from the opposite side of said plane to said one side face for receiving an associated male prong extending from the complementary plug, which prong has a larger cross sectional dimension than the first and the second male contacts, said female con tact members being respectively accessible Within said body through aligned openings in said body extending from said female members to said end face, said body having a cavity extending inwardly from said side face in spaced relation to said end face and in surrounding relation-to the opening associated with the first male contact, a barrier of relatively rigid dielectric material located in said cavity and extending transversely of the first opening, said barrier having a passage therein in alignment with said opening which passage is of a size such as to permit the passage of the first male contact through said first body opening and to prevent the passage through said first opening of the male pron-g, said body having a shoulder on said side face adjacent said end face and located on a line which extends perpendicular to said plane and through the third female contact member, whereby said shoulder blocks the travel of the male prong to thereby .p-revent insertion of the first and second male contacts in misassociation with the first and second female contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,897,829 Watts Feb. 14, 1933 1,907,968 Hunt May 9, 1933 2,105,465 Bannon Jan. 18, 1939 2,610,999 Silver 1 Sept. 16, 1952 2,716,737 Maberry Aug. 30, 1955 2,742,624 Stevens Apr. 17, 1956 2,752,581 Benander June 26, 1956 2,770,786 Chelton Nov. 13, 1956

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