US 3781769 A
In a wiring device of the female connector type, female contacts are provided in an interior chamber of an insulating housing for frictional engagement with an inserted blade of a male attachment plug; the housing chamber has fixed interior walls with at least one deformable projection extending therefrom for deformably bearing against the spring contact element when the latter is deflected by an inserted blade to maintain the alignment of the element in use.
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Description (OCR text may contain errors)
United States Patent 1 Wiley WIRING DEVICE SUCH AS FEMALE CONNECTOR WITH DEFORMABLE INSULATING HOUSING ELEMENT FOR MAINTAINING CONTACT ALIGNMENT  Inventor: Roy A. Wiley, Huntington, Conn.
 Assignee: Westinghouse Electric Corporation,
 Filed: Aug. 15, 1972  Appl' No.: 280,938
 US. Cl. 339/189 R, 339/64 R  Int. Cl. H01r 13/50, H01r 21/28  Field of Search 339/59, 61, 64, 65,
 References Cited UNITED STATES PATENTS 3,648,213 3/1972 Kobler 339/59 R 3,479,635 11/1969 Stark et al.. 339/64 M 3,179,738 4/1965 De Lyon 339/128 X Dec. 25, 1973 2,074,958 3/1937 Chirelstein 339/191 A X 2,101,713 12/1937 Jolliffe 339/191 A X 3,121,599 2/1964 Modrey 339/189 R X FOREIGN PATENTS OR APPLICATIONS 1,247,634 10/1960 France 339/61 R Primary ExaminerMarvin A. Champion Assistant Examiner-Lawrence .l. Staab AttorneyA. T. Stratton et a].
[57 ABSTRACT In a wiring device of the female connector type, female contacts are provided in an interior chamber of an insulating housing for frictional engagement with an inserted blade of a male attachment plug; the housing chamber has fixed interior walls with at least one deformable projection extending therefrom for deformably bearing against the spring contact element when the latter is deflected by an inserted blade to maintain the alignment of the element in use.
4 Claims, 4 Drawing Figures WIRING DEVICE SUCH AS FEMALE CONNECTOR WITH DEFORMABLE INSULATING HOUSING ELEMENT FOR MAINTAINING CONTACT ALIGNMENT BACKGROUND OF THE INVENTION The invention relates to wiring devices and particularly to female connecting devices.
In female connecting devices used with male attachment plugs for making electrical connections, it is necessary that the female contacts be in proper alignment with the entry slots or openings to frictionally engage an inserted plug blade. Upon insertion ofa plug blade, the contact element or elements normally deflect.
Contact elements that are intended to deflect in use cannot be rigidly secured in a single fixed position when initially formed. Thus, the chamber in which the contact elements are located is required to have space for not only the female contact in its undeflected position but also to receive the male plug blade and to accommodate the deflected movement of the female contact. If close dimensional tolerances are maintained for the housing chamber and the contact elements the desired alignment can be maintained. However, many dimensions are involved and in normal practice for economic construction of such devices, a buildup of tolerances can sometimes result in difficulty to maintain the alignment of the contacts properly with the opening slot. Among the variables normally incurred are those in the dimensional tolerances of the spring contact elements themselves, the features of the housing in which contact elements are contained, and the amount of deflection incurred through the insertion of a plug blade. These variables make it impractical to decrease the dimensions of the chambers and molding of the housing to maintain the contact elements in their proper location.
It was as a result of an effort -to alleviate the aforementioned problems of contact alignment that the present invention came about.
For general information with respect to a prior art connecting device'relevant to this invention and which may be improved in accordance with this invention, reference may be made to Hawkes US. Pat. No. 3,189,865, June 15, I965.
SUMMARY OF THE INVENTION In accordance with this invention, a wiring device, such as one of the female connector type, may have the usual female contacts in an interior chamber of an insulating housing for frictional engagement with an inserted blade of a male attachment plug. The housing chamber has fixed interior walls but with at least one deformable projection extending therefrom for deformably bearing against the contact element when deflected by an inserted blade to maintain the alignment of the element in use.
In a Preferred form of the invention, the deformable projections are of the same material as the insulating housing and are molded at the same time and integral with the principal housing structure. For the desired deformability of the projections, it is merely necessary that they be made thin enough. For example, in devices made of molded nylon material the deformable projections may. be thin riblike members having a thickness of about .020 inch. In the normal undeflected position of the contact elements, they may not-touch the deformable projections or not exert any deforming force thereon. However, upon insertion of a plug blade causing deflection of the contact elements, a portion of the latter moves into substantial contact with the deformable projection. This contact results in deforming the projection to a position to accommodate the deflected extent of the contact elements and yet to limit any additional deflection thereof beyond that merely required to accommodate the plug blade. After only one or a few times of use, the deformable projections will tend to take a permanent position as deformed which will subsequently be maintained in use andmaintain the desired contact alignment.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an example of a female connecting device and a mating male attachment plug which may be improved in accordance with the present invention;
FIG. 2 is a partial sectional view of the female connector of FIG. 1 to illustrate an example of a housing and contact arrangement in accordance with the present invention;
I FIG. 3 is a cross-sectional view of the device portion of FIG. 2 taken along line IIIIII;.and
FIG. 4 is a view of the structure of FIG. 2 with a plug blade inserted therein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there is an overall view of a male attachment plug 10 and a mating female connector 20 which may incorporate the present invention. The male plug 10 need not be modified to obtain the improvement of the present invention. Plug 10 is illustrated for general reference and comprises an insulating housing 12 of generally cylindrical form with a back end of housing 12 having an opening for receiving an electrical cord 14 of a number of wires which are secured to terminals within the housing. Plug blades 16 extend from the front of the housing for engagement with the female connector 20. In the example shown, plug 10 has three plug blades 16 including two outer blades intended for connection with the wires carrying the electrical power in the cord 14 and a centrally located blade, of somewhat different configuration, connected with an additional wire in the cord 14 for a ground connection.
The female connector 20 has an insulating housing 22 with a back end opening to receive a line cord 24 which includes wires connected to terminals contained within the housing 22, which terminals have female contact elements connected thereto and each located to receive a plug blade 16 when the latter is placed in one of the blade receiving apertures 26 which are substantially matched in configuration and location as the plug blades 16. In this example device, the improvement of this invention is applied to the housing and contact configuration within the chambers communicating with openings 26 for the outer blades 16 of the plug 10 and that for the ground pin need not employ the invention as its contact element is normally a fixed sleeve frictionally engaging the grounding pin of the plug.
FIG. 2 shows a portion of the structure of the female connecting device 20 including that part of the housing 22-that defines one chamber 25 communicating to one blade 16 frictional engagement therewith is provided as shown by FIG. 4.
In FIG. 2 the contact elements 31 extend toward each other to a knee 32 after which a portion 34 flares out to aid in receiving blade 16. In the relaxed position of FIG. 2 the flared out portions 34 do not engage any part of the housing. There are located within the housing chamber 25, and extending from an interior surface of the chamber, deformable projections 36 that are preferably molded with the material of the principal portion of the housing 20 and are of a material such as nylon that is not brittle and which permits deformation when formed of small dimensions. In the normal position of FIG. 2, the flared out portions 34 do not touch the deformable projections 36 or if they do touch they exert no appreciable pressure or force thereon.
The view of FIG. 3 shows a cross-section of the structural portion of FIG. 2 to illustrate the thinness of the projection 36 in relation to the principal housing wall portion 37. Projections 36 are rib-like elements extending along the wall surfaces of the housing chamber 25 and have a thickness of about 0.020 inch in the type devices described.
As can be seen in FIG. 4, upon the insertion ofa plug blade forcing apart the contact elements 31, the flared out portions 34 engage the projections 36 in a manner that results in deformation of the projections. After one or only a few times of use in this manner the projections 36 will tend to take a permanent form as deformedby the contact elements 31 while preventing any additional movement thereof other than that required to ac commodate the blade 16. Consequently, the dimensional tolerances with which the contact elements 31 and the housing are formed can be somewhat looser than previously required or with the same tolerances a higher degree of successful manufacture will result.
From the foregoing it is apparent that the invention may be applied to wiring devices generally in which contact elements are located with space required to provide for their deflection in use and thus they cannot be maintained in a rigid fixed position. In such devices, the use of any one or more deformable projections in accordance with this invention will provide a means to maintain the proper location of such contact elements throughout use.
1. A wiring device comprising: an insulating housing having a chamber and a plug blade receiving aperture through an exterior wall of said housing to said chamber; at least one female contact within said chamber, said female contact comprising at least one spring contact element located in relation to said blade receiving aperture to frictionally engage an inserted blade; said chamber having fixed walls from which said contact is spaced, and at least one deformable projection extending from a chamber wall to maintain alignment of said contact, said deformable projection being integrally molded with said insulating housing and extending to a location at which it is deformed by said contact at least when said contact is deflected upon blade insertion; said female contact comprising two spring contact elements that are deflected away from each other upon blade insertion, and one said deformable projection being located extending from a chamber wall adjacent each said spring contact element; said two spring contact elements being supported at a terminal with means for connecting a wire thereto, a portion of each of said elements extending proximate to each other and then flaring apart from each other at a free end thereof thereby forming a knee in each element between the two of which is the location of closest proximity and of greatest frictional engagement with an inserted blade, and said deformable projections being contacted by said flared apart portion of said elements.
2. The subject matter of claim 1 wherein: said deformable projections are in the form of thin elongated projections whose direction of elongation is generally parallel to the direction of blade insertion.
3. A female connecting device for use with a male attachment plug for making electrical connections comprising:
a housing of insulating material having a front wall with openings communicating with interior chambers;
a female contact located within each said interior chamber and comprising at least one spring contact element for frictional engagement with an inserted blade of the male attachment plug;
said housing chamber having fixed interior walls with at least one deformable projection extending therefrom for deformably bearing against said spring contact element when said element is deflected by an inserted blade to maintain the alignment of said element in use, said projection being thin compared with its extent from said wall and having a thin edge against which said contact element bears with permanent deformation of said projection.
4. The subject matter of claim 3 wherein: said female contact comprises a pair of opposing spring contact elements for engaging therebetween an inserted blade and one said deformable projection extends from an interior chamber wall proximate each said element.