US 3636501 A
Description (OCR text may contain errors)
United States Patent Walsh [451 Jan. 18, 1972 54] ELECTRICAL CONNECTOR  Inventor: Donald K. Walsh, 26 Liberty Bell Circle,
Houston, Tex. 77024  Filed: Nov. 4, 1969  Appl.No.: 873,840
3,106,599 10/1963 Leitner et a1. 1 74/12 3,127,230 3/1964 Marquis et al ....339/118 3,170,752 2/1965 Van l-lorssen ..339/258 X Primary Examiner-Richard E. Moore Attorney-Harry C. Bierman, Jordan 8. Bierman and Bierm an and Bierman  ABSTRACT An electrical connector comprising a generally cylindrical electrally conductive rod having an axial bore therein forming a tube open at at least one end and having walls at least a por- I tion of which are shaped in the form of a bellows. The bore is adapted to receive at least one electrical conductor and in its preferred form the hollow portion of the rod is filled with an electrically conductive liquid which is relatively incompressible as, for example, mercury.
9 Claims, 10 Drawing Figures PATENTEB JAN 1 8 1972 SHEET 1 OF 2 FIG.
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PAIEmEnJmm 3.536501 SHEET 2 OF 2 FIG. 9
A'ITURNEYS ELECTRICAL CONNECTOR The present invention is directed to an improved electrical connector, more specifically, to an electrical connector which is highly resistant to flexural strain.
In many electrical applications it is necessary to incorporate a junction between a plurality of electrical conductors. As a variation of such a device a terminal point or similar electrical contact is required. In many such applications, the conductor is required. In many such applications, the conductor is soldered, swaged, crimped, or otherwise secured onto a pin or socket housed within the shell of an electrical connector. In areas of vibration and/or pressure, there is a great tendency for the conductor to fatigue at or very close to the junction point. This is because the pin or socket is comparatively rigid and fixed, while the conductor tends to flex as a result of any movement thereof.
Especially in devices used beneath the surface of the water, such as for oceanography and naval applications, this weakness is extremely critical. Similarly, in specialized situations such as space vehicles and the like, where reliability is one of the most important factors, this particular weakness is one which must be overcome. It has been found that even where the back ends of plugs and connectors are rigidly set, pulsating pressure will cause a failure due to minute creeping movement of the copper conductor itself.
It is among the objects of this invention to provide an improved electrical connector which is capable of withstanding substantial vibration and flexure without risk of failure of the conductor due to fatigue.
It is also among the objects of this invention to provide an electrical connector which is particularly adapted to be used under substantial pressures.
It is further among the objects of this invention to provide an electrical connector which is of simple constriction and of great value in any situation in which it will be subject to substantial vibration.
In practicising this invention there is provided a generally cylindrical rod manufactured of any electrically conductive material. Beryllium copper has been found particularly suitable for this purpose.
The rod has an axial bore therein which may extend completely through the rod or in the preferred form of the invention, stop short of one end. Thus, there is formed a comparatively thin-walled hollow tube which may have a portion near one end solid.
The thin-walled portion is bent in such a manner as to provide bellows along a given length thereof. In the broadest form of the invention, the conductor is inserted part way into the open end of the rod and the thin walls at that point are crimped around it thus ensuring excellent electrical contact. The bellows permit the rod to flex and distribute the flexural strain evenly over their entire length. This prevents a concentration of stresses both in the rod and in the conductor itself and thereby minimizes or eliminates failure due to fatigue.
For certain applications (particularly those for operation under high pressures) the stability of the device can be improved by filling the axial bore with a substantially incompressible electrically conductive liquid. Mercury has been found quite suitable for this purpose.
In such a case, the bore after the bellows have been formed is filled with mercury and a sealing plug is wedged therein. For
additional safety, the thin walls may be indented just behind the plug in order to retain it in position.
Alternatively, for certain applications, a vacuum within the axial bore may be found desirable. This would tend to reduce electrical noise" under certain circumstances. Here too, the sealing plug would be inserted in much the same way.
An alternative form of plug consists of a cylindrical member having an axial hollow therein. The hollow is open at one end only and the outside diameter of this member is such that it just fits snugly within the axial bore. This member is inserted in the same manner as the plug with the open end facing out. That way the electrical conductor can be inserted into the hollow thereby eliminating an additional fitting.
In the accompanying drawings, constituting a part thereof and in which like reference characters denote like parts:
FIG. 1 is a view partly in section showing one form of the rod prior to the formation of the bellows;
FIG. 2 is a view similar to FIG. I, but fully in section, showing the rod after the formation of the bellows and having the simple plug inserted;
FIG. 3 is a sectional view of the modified fonn of sealing P g;
FIG. 4 is a fragmentary view showing a portion of FIG. 2 with the sealing plug retained by an indented portion of the walls;
FIG. 5 is a perspective view showing the device adapted to a typical MIL-type socket and crimp;
FIG. 6 is a view similar to FIG. 5 showing the application of the device to a MIL-type pin; and
'FIGS. 7-10 show variations of the basic device intended for use as right angle, inline, offset and terminal connectors, respectively.
The invention comprises rod 1 having a axial bore 2 open at at least one end 3 thereof. Other end 4 may be similarly open or solid as shown in FIG. 1. Bellows 5 are formed in thin wall 6 intermediate the ends of axial bore 2.
In one embodiment of the invention, axial bore 2 is filled with mercury 7 and plug 8 is inserted therein. Retaining means 9 consists of an indentation in wall 6 which prevents plug 8 from slipping out.
A conductor (not shown) usually in the form of a wire is inserted into end 3 of bore 2 and wall 6 may be crimped therearound.
The alternative sealing plug (shown in FIG. 3) consists of member 10 having a solid end 11 and an axial hollow 12. Hollow 12 is open at outer end 13.
The conductor is inserted into hollow I2 from outer end 13 and member walls 14 are crimped therearound. Member I0 along with the conductor crimped therein is inserted into end 3 of bore 2. Solid end 11 takes the place of plug 8 (see FIG. 2) and wall 6 is indented in the usual manner to retain member 10 is position.
As shown in FIGS. 5 and 6, the device of the present invention can readily be adapted to standard MIL-type connectors which are presently in wide use. In FIG. 5 there is shown the connector of the present invention attached to a typical MIL socket 15. In FIG. 6, the device of the present invention is shown applied to a typical MIL pin 16.
The device lends itself to manufacture in various forms analogous to those presently used in this field. In FIG. 7 is shown a two conductor right angle connector 17 having two sets of bellows 6a and 6b. The conductors are inserted in ends 3aand 3b of axial bores 2a and 2b in the same manner as heretofore described. The right angle 18 is provided between bellows 6a and 6b.
The inline form is shown in FIG. 8 comprising bellows 5 and axial bores 2a and 2b. Similarly, FIG. 9 provides an offset connection through offset portion 19.
FIG. 10 is a terminal having bellows 5 and axial bore 2 in the usual manner, but connected to eye 20 having hole 21 therein. Hole 21 is adapted to be mounted on a terminal post or screw, thereby holding the entire connection in position.
As an additional refinement, it has been found particularly advantageous to size the bellows portion such that the overall connector will have electrical characteristics matching those of the wires being connected.
As can be seen from the foregoing, the device of the present invention is adaptable for a wide variety of uses. It is therefore to be broadly constructed and not to be limited except insofar bore being filled with an electrically conductive substantially incompressible liquid, and means for retaining said liquid in said bore.
2. A connector according to claim 1 wherein said means comprises at least one plug sealing the liquid in the closed bore. a
3. A connector according to claim 1 wherein said liquid is mercury.
4. A connector according to claim 2 wherein said plug is at at least one end of said bellows, retaining means on said rod keeping said plug in position.
5. A connector according to claim 2 wherein said plug comprises an electrically conductive member having an exterior generally complementary to said bore and in contact therewith, said member having an axial hollow open at an outer end and closed at an inner end, said hollow adapted to receive said conductor.
6. A connector according to claim 5 wherein said member is in contact with said liquid.
7. A connector according to claim 1 wherein said bore extends along only part of the axis of said rod, a sealing plug in said bore located at an end of said bellows nearer the open end of said bore, retaining means on said rod keeping said plug in position, said plug comprising an electrically conductive member having an exterior generally complementary to said bore and in contact therewith, said member having an axial hollow open at an outer end and closed at an inner end, said hollow adapted to receive said conductor.
8. An electrical connector comprising a generally cylindrical electrically conductive rod having an axial bore therein forming a tube open at at least one end and having walls, at least a portion of said walls constituting a bellows, at least one electrical conductor in said bore, said rod being bent to form legs, and bellows in each of said legs.
9. An electrical connector comprising a generally cylindrical electrically conductive rod having an axial bore therein forming a tube open at at least one end and having walls, at least a portion of said walls constituting a bellows, said bore being adapted to receive at least one electrical conductor, said bore being filled when an electrically conductive substantially incompressible liquid, means for retaining said liquid in said bore, said bore extending along only part of the axis of said rod.