US2739295A - Electrical connector - Google Patents

Description

March 20, 1956 ALDEN 2,739,295

ELECTRICAL CONNECTOR Filed Feb. 10, 1951 United Sttes 2,739,295 ELECTRICAL (IQNNECTOR John M. Alden, Needharn, Mass. Application February 10, 1951, Serial No. 210,421 3 Claims. (Cl. 339-258) In the construction of female electrical connectors of the molded type it has been found highly desirable to mold the insulation around leads attached to contacts which form an insert for the mold. This design gives excellent strain relief as the insulating material becomes homogeneously bonded to the leads and clips. It also gives better insulation as there are no openings or uninsulated portions to the connector except the entry for the male pin. However, to get this type of construction it has been the practice to machine or otherwise manufacture the female contact to very close tolerances from eavy gauge stock so that the contact engages the pin with a light push fit without interfering with the surrounding molded material which acts only as insulation. The manufacturing of such contacts is slow and expensive and not adapted to punch press or high speed mass produc tion techniques. The resulting connectors have the additional disadvantages of being large, awkward, heavy, limited in variations in contact pressure and retention force obtainable, and subject to electrical leakage paths particularly at the point where the associated conductor enters the molded portion.

In a broad aspect the invention contemplates an electrical connector comprising a recessed contact or insert formed of a resilient material such as a suitable metal which is electrically conducting. The insert is yieldably arranged and constructed, for example as a cup or socket having a split side wall, to deform so as to accommodate a conducting contact member or pin of the electrical component associated with the connector. The insert is molded in an enclosure of insulating material, such as a suitable plastic whereby the resiliency of the portion of insulating material adjacent the cup side wall or other yieldable part of the insert restrains the deformation of such part to increase the electrical contact pressure upon the mating pin, the value or amount of the pressure being determined by the relative dimensions of the insert wall and adjacent insulating material and by the desired retention force of contact with the mating pin. When an insulating material which is relatively yieldable is employed, the material is molded into contact with substantially the entire length of the side wall, the contact pressure being determined by the proportioning of the thicknesses of the wall and adjacent material. If a relatively stitf molded material is used, it is preferable that only a portion of the side wall of the insert be brought into contact with the surrounding enclosure, clearance being provided between the remaining length of the sidewall and the molded material so that the desired contact pressure is obtainable by varying the length of the contacting portion.

In a more specific aspect one end of an electrical conductor such as a flexible insulated wire is spot welded or otherwise attached to the insert. The insulation of the Wire is either of the same material as that of the molded enclosure so that subsequent to the molding operation the wire insulation and enclosure form a homogeneous structure, or of a material having physical characteristics such that an integral bond is formed therebetween during the 2,739,295 Patented Mar. 20, 1956 molding operation thereby in either case to eliminate a leakage current path at the junction point.

These and other objects and aspects will be apparent from the following description of several specific embodiments of the invention which refer to a drawing wherein:

Fig. 1 is a side elevation view of a first embodiment of the invention which is adapted to engage the pin of an electrical component such as a vacuum tube;

Fig. 2 is a bottom view of the embodiment shown in Fig. 1;

Fig. 3 is a sectional view on line 33 of Fig. 1;

Fig. 4 is a sectional view on line 4-4 of Fig. 2;

Fig. 5 is an isometric view of the insert;

Fig. 6 is a sectional view similar to Fig. 3 of a second embodiment of the invention;

Fig. 7 is a sectional view similar to Fig. 4 of the second embodiment;

Fig. 8 is a side elevation view of the male and female portions of a connector in disengaged relationship;

Fig. 9 is a similar view to Fig. 8 with the connector portions in engaged relationship;

Fig. 10 is an end view of the female portion of the connector;

Fig. 11 is a sectional view of the male and female portions in engaged relationship; and

Fig. 12 is an enlarged fragmentary sectional view showing the details of construction of the female portion.

The first embodiment of the invention chosen for the purpose of illustration consists of a connector or cap (Fig. 1) for the mating pin of a vacuum tube which is not shown. The cap 20 comprises a contact or insert 22 formed (Fig. 3) of a strip of an electrically conducting material such as tinned bronze or brass in the shape of a substantially cylindrical cup whose internal diameter is in the disengaged position slightly less than the diameter of the mating pin. The insert cup is provided with two axial slots or spits 24 diametrically disposed to form two side wall portions 25 which yield as the mating pin (not shown) is inserted therein. The closed end of the cup is provided with an aperture 26 (Fig. 5) through which one end of a flexible electrical conductor such as the insulated wire 28 is inserted. The tip of the back and anchored to the end of the spot welding or soldering.

The assembled insert 22 and wire 28 are then molded in the conventional manner well known to those skilled in the art Within a substantially cylindrical enclosure 30 of a thermoplastic material such as polyethylene, which is provided with a radially projecting boss 32. The insulation surrounding the wire 28 is preferably, although not necessarily of the same material as that surrounding the insert 22 so that during the molding operation the boss 32 and the wire insulation are integrally bonded to form a homogeneous piece thus greatly increasing the length of the path of the leakage currents. As is best shown in the isometric view Fig. 5, the end portions 25 of the strip forming the side wall of the insert cup are cut back as at 34 to facilitate bending of the insert during manufacture, as described below. These cut backs also serve the additional purpose of providing a recess which is filled by insulating material of the enclosure 30 during the molding operation thereby to anchor the insert 22 more securely in the enclosure. The flow of the molded material through the aperture 26 in the closed end of the insert further aids in anchoring the insert in the enclosure.

It is to be particularly noted that an insert 22, such as described above, can be readily manufactured from a strip of light gauge sheet material by a multiple action die in a simple punch press operation with resulting economies in manufacturing costs. Because of the reinforcing of the pin contacting insert side wall material of the enclosure 30, the gauge of the material of wire 28 is then bent cup, for example by contact pressure against the mating pin (not shown) is' obtained.

In the above described embodiment, the reinforcing portion of the insulatingmaterialiextends the enti'relength of the insertside wall portions 25.- When, however the enclosure is molded of a more rigid plastic material, rather than reducing the thickness of the insulating material' to the point: of possible electrical breakdown, it is advantageous to provide only partial backing for the insert side wall portions as in the modified cap 26a shown in Figs. 6 and 7; The cap 202: has the same advantages and features and is generally similar to the cap described in detail heretofore with the exception that the enclosure a is made of 'a less yieldable material and a clearance provided between the lower side wall portions 25' of the insert 22 and the surrounding insulating material as at- (Figs. 6 and 7) thereby reducing. the reinforcing action of the insulating material so that the desired contact pressure can be obtained without dangerously reducing the thickness of the insulation. a

The above described principle is not limited to tube cap connectors nor to inserts having a cylindrical socket, but as is shown in Figs. 8 through 127 can be applied to the female portion of a high voltage connector which mates with the pin of a male portion as is shown in Fig. 11. In this connector the socket insert 52' is generally triangular in shape as is shown in Fig. 10 having, a split along the apex to permit the two adjacent sides to separate as the pin of the male portion 55 is inserted. The side of the insert 52 opposite the apex slit is extended on both ends and bent back in opposite directions. The forward end is bent back upon itself to form a tab 54 to which the connecting wire 28b is welded or otherwise anchored. The rear end 56 is bent at right anglesto close thev bottom of the insert.

The insert 52 is preferably manufactured by a punch press operation and molded in the surrounding insulating enclosure so that the light gauge metal of the side walls of the insert 52 are reinforced by the surrounding insula tion, the thickness of which is determined by the contact pressure desired in an analogous manner to that described heretofore in connection with the tube cap 20. Although in the connector shown, the walls of the insert 52 are reinforced along their entire length, it is also possible to provide clearance between a portion of the insert sidewall and the adjacent insulating material in a manner similar to that described in connection with the tube cap 20a shown in Figs. 6 and 7 so as not too greatly to reduce the thickness of the insulating material.

A further feature of the female connector 50 is two opposed offsets 60 (Fig. 10) indented in the sidewalls of the insert 52. These offsets60 are backed by the resilient insulating material so that they act as a click cletent exerting considerable retention force upon engaging a corresponding groove in the male connector portion 55.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications. and equivalents which fall within the scope of the appended claims;

I claim:

1. In an electrical connector; a; unitarycontact having an integral portion for yielding receiving a mating contact member, a lead wire connected to said contact, an insulating covering on said wire, and an enclosure of resilient, insulating material molded to a part of said yielding portion to resist yielding of said part when said memher is received and spacedfrom another part of said yielding portion so as to permit yielding of said other part unimpeded by pressure from said enclosure when said enclosure is formed of relatively stifi yielding material, said enclosure being intimately bonded to said insulation mechanically to secure the insulated wire to the enclosure.

2. In an electrical connector, a contact having a portion for yieldingly receiving a mating contact member, a lead wire connected to said contact, an insulating covering on said wire, and an enclosure of insulating material molded to said contact, said enclosure being intimately bonded to said insulation mechanically to secure the insulated wire to the enclosure,v said contact and enclosure havingyield ingly parallel walls, said contact walls being flexible and having free ends, and said enclosure wall having affi'rst portion spaced from said free end contacting and pressing on the yielding contact wall and a second portion; with lateral clearance from said free end, thereby reducingthe reinforcing action ofthe insulating material so that the desired contact pressure can be obtained independentlyof the relativestifiness of the enclosure.

3. In an electrical connector, a contact for yieldingly receiving a mating contact member, a lead wire connected to said contact, an insulating covering on said wire, and an enclosure for insulating material molded to said contact, said enclosure being intimately bonded to said insulation mechanically to secure the insulated wire to. the

enclosure, said contact comprising a transverse wall. and a split side wall extending therefrom, a portion of said side wall adjacent said transverse wall being of reduced width flexibly to hinge the free end of the side wall to saidl'transverse wall, said enclosure having a parallel wall with. an inner portion contacting and pressing on said' reduced portion and an outer portion with lateral clearance from. said free end, thereby reducing the reinforcing action ofthe insulating material so that the desired contact pressure,

can be obtained independently of the relative stifiness of the enclosure.

References Cited in the file of'this patent UNITED STATES PATENTS Kjell-Berger Aug; 8, 19501

Images