US2935722A - Electrical socket connector with mercury contact - Google Patents

Description

www o o c G w. L. KAclN Filed Nov. 14, 1957 ELECTRICAL SOCKET CONNECTOR WITH MERCURY CONTACT May 3, 1960 INVENTOR. WILLIAM L.KAc|N BY j C?) a ATTORNEY oo coco ole o o o o o a'o c o ono do o oo aoc o ELECTRICAL SOCKET CONNECTOR WITH MERCURY CONTACT Wiiliam L. Kacin, Flushing, N.Y.,= assignor to Faxiniile, Inc., New York, N.Y., a corporation of Delaware Application November 14, 1957, Serial No. 696,373

9 Claims. (Cl. 339-118) The present inventan relates to the an of electrical'- ployed devices including spring contacts for effecting'.

quick detachable connections to other electrical circuits. Because of the small area of contact available the direct electrical connection between the fine wire terminal and an associated circuitthrough a conventional connection is frequently lost. This is due to carbonization of the contacting surfaces, development of ylooseness in the springs, and other mechanical faults. A

The present invention has as its principal object the provision of a connector which is free from spring con'- tacts and in which direct electrical connection is accortiplished'via a conductive fluid in a metal tube havingk a closed end. A further object is to provide a plug and receptacle assembly in which one or more tine wire prongs may be seated in a receptacle containing one or more bodies of conductive iiuid such as mercury. A further object is to provide a. receptacle containing one or more bodies of a conductive liquid, with the liquid exposed to the exterior of the receptacle via one or more open passages. A further object is to provide aconnector member in the form of a block supporting a conductive container having a body of mercury therein with the block having one ormore open passages for insertion of electrical conductors into the body of mercury.

The other and further objects `of the invention will become apparent yfrom the following description taken together with the drawing wherein:

Fig. l is a plan View of a plug and receptacle embodying the invention.

Fig. 2 is a sectional View taken on lines v2 2 of Fig. l, with the plug and receptacle interttedgwith each other.

Fig. 3 is a sectional view on an enlarged scale of another form of receptacle. Y

Fig. 3A is a fragmentary sectional viewsimilar to Fig. 3 illustrating a modification of the invention. Y

Fig. 4 is a fragmentary sectional View on an enlarged scale of an intertted plug and receptacle. n

Figs. 4A and 4B fare fragmentary sectional views similar to Fig. 4 employed in explaining the invention.

Fig. 5 is an end View of the receptacle shown in Fig. l.

Fig. 6 is a perspective View of the .plug shown in Fig. l.

Figs. 7 and 8 are end views of other. forms ofplug and receptacle respectively.

Figs. 9 and 10 areA perspective views of further forms of plug and lreceptacle respectively.

Fig. 11 is a perspective view of a portion of a receptacle` illustrating a stage in the assembly thereof. v

Referring to Figs. l, 2 and 6, there is shown a plug which is formed of a block of insulating material such as plastic, ceramic, or the like. Embedded in tlie block 21 is a. plurality of wires 22 disposed in a coplanai" parallel array. End 23 of the block is' dat. Out of this end pro'- nited tates Patent ject the terminals 24 of the wires 2.2. These terminals serve as prongs of the plug. The wires may be formed of stainless steel or other material which is not wettable by the conductive uid in the connector to ybe described. Block 21 may be provided with a pair of recesses 25 `for receiving the locating pins 26 best shown in Fig. l. It is intended that the prongs 24 be inserted into the receptacle and the portions of the wires 22 extending out of other end of the block be connected in -a suitable elec trical circuit.-

The structure of the receptacle 30 is best shown in the Figs. 1, 2', 4 and 5. The receptacle may be formed of a block 31 of insulation material in which is seated a metal tube or container 32 having an open end 33 and a closed end 34. The tube is cylindrical in form and has a cylindrical cavity which contains a body 38 of a conduc= tive iuid. This iluid may be a liquid metal suchas mercury, gallium or other metal or alloy thereof which is liquid in form at 4the temperature at which the connector is to be used. Secured to end 34 of the tube by means of solder 39 is wire 40. This wire is part of an electrical circuit to which it is desired that oneeof wires 22 make direct electrical contact. Another block of insulation material 42 having a recess 43 is inserted over the open end of the tube, a pair of plates 50 and 5 1 hold blocks 31 and 42 together ina unitary assembly. Screws 52 extend into' the blocks from the plates for assembling the connector.

in Fig. 3 is shown another form of receptacle which includes a block of insulation material 45. The block is provided with a bore 46 in which is seated a tube 35 containing a body of a liquid metal 38 such as mercury. Wire' 4G is attached by solder 39 to the end 34 of the tube. This end projects out of the rear side of the Vblock so that the wire can be readily attached thereto; Blocks 42 and 4S in Figs. 2 and 3 are each provided with a narrow passage 55. This passage communicates directly with the open end 33` of the tube 35. The outer end of the passage is formed as a concave countersunk recess 56. The diameter of the open end 33 of the tube is at least three times the diameter of passage 55 so that the area of end 33 is not less than about ten times larger than the cross-sectional area of the passage 55.

When the plug is disconnected from the receptacle, the outer end of the body of mercury 38 forms a convex meniscus 6i) near the inner end of passage 55. This cnvex shape of the meniscus is formed when Athe metal of tube 35 is not wetted by the mercury.` 'The tube 35 may be made of stainless steel, chromium and other metal which does not react with the conductive iiuid. It will be noted that because of the high surface tension existing at the open end 33 of the tube the curved meniscus is presented by the body of mercury to the inner end, of passage 55. This meniscus requires a considerable force to be penetrated Or broken. Normal vibration or shaking of the connector is insufcient to break the me; niscus, and thus minute droplets of the conductiven fluid cannot pass through the passageway. The tube should be only partially lled with mercury to allow room fot', expansion of the metal due to increase in ambient terri'-y pe'rature. When the prong 2.4 is inserted into the body of mercury as best shown in Fig. 4 a cusp 61 is fried around the prong at the point of entry in'to the liquid metal. This re-entrant shape assumed by the meniscus at .the prong is structurally stronger than the original convex shape of meniscus 69 as shown in Fig. 3. The

annuiar space S within the passage around .prong 24 is less than the previous unoccupied space so that an even i greater resistance to leakage of the mercury through kthe passage 55 exists; e e A e It is necessary that the crios's'sectional area of passage' 55 be slightly larger than the diameter of prong 24 in order that the prong may freely enter the body of mercury and to provide means for the escape of air from the tube as the prong is inserted therein. This space also prevents mercury being drawn out by suction when the prong is withdrawn. VThe convexity of the meniscus around the prong 24 in Fig. 4 indicates that the mercury does not wet the metal of the prong which. is wetted by mercury a concave meniscus 64 is formed as shown in Fig-3A. The prong should not be made of a metal which is wettable by mercury. lf such metal were used then a conical area 62 would be formed in the meniscus 60 around the prong as shown in Fig. 4A, and the mercury would be drawn out of the tube 35 by the wet prong when the plug was separated from the receptacle.

In Fig. 4B, the prong 24 is shown inserted into a concave meniscus 64 formed when the tube 35 is wetted by the mercury. A cusp 61 forms around the prong which is not wetted by the mercury. This curved form of the meniscus has a greater resistance to breakage than the concave form of the meniscus 64 so that leakage of mercury past the prong cannot take place in passage 55.

In Fig. 7 is shown a plug including a block 70 having prongs 24 disposed in a rectangular array. The prongs are arranged in a plurality of rows. Four recesses 25 are provided near opposite corners of the block 70 for receiving pins 26 of the receptacle 72 which is shown in Fig. 8. Passages 55 in the receptacle are arranged to receive the prongs 24. Each passage terminates in a countersunk opening 56.

In Fig. 9 the plug block 74 carries a single prong 24 which is the terminal of wire 22. Recesses 25 in block 74 receive the two locating pins 26 carried by receptacle 75 as shown in Fig. 10. A single passage 55 is provided in receptacle 75 to receive the prongs 24. Each of the passages 55 in receptacles 72 and 75 terminate at the openings of tubes 35 in the same manner as shown in Figs. 2, 4.

Fig. 11 shows a step in the procedure for assembling the receptacle 30. Tube 35 to which wire 40 has been soldered is partially embedded in block 31. The open end 33 of the tube is accessible for inserting of a quantity of mercury or other conductive fluid into the tube. After the mercury is inserted in the tube the capping block 42 (in Fig. 2) is placed over block 31 and then plates 50 are attached.

' In the form of the invention shown in Fig. 3 a single block 45 is used for the receptacle so that fastening plates 50 are not required.

The plug and receptacle block may be made of any suitable insulation material such as plastic, ceramic, glass, etc. Abutting faces of the plug and receptacle blocks should be flat to fit iiush against one another and provide a sealed joint between the blocks. If the conductive fluid exhibits any tendency to vaporize such as might occur due to heating of the `connector during extended use, this tendency may be counteracted effectively by improving the joint between the faces. This may be done by coating the faces with rubber or other flexible material to insure a hermetically sealed joint between the plug and receptacle blocks where the prongs are fully inserted into the bodies of conductive liuid. The tubular containers 35 are preferably made of conductive material such as a suitable metal. They may be made of nonmetallic material provided that the wires 40 are extended to pass through the ends 34 to make direct electrical contact with the conductive fluid bodies 3S. It is possible Yto use other conductive fluids than liquid mercury and liquid -gallium in the tubes 35. If desired the fluid may be of any substance which has a low vapor pressure and high surface tension so that it will not evaporate or ow through the narrow passages 55 in the receptacles. Suitable liquids are viscous oils, polyethylene glycol and ,4 the like. The body may be rendered electrically conductive by addition of minute particles of metal such as silver, aluminum, copper, etc. The particles should be sufliciently small to be retained in permanent suspension in the liquid. The material of the prongs 24 must be so selected that they are not wetted by whatever liquid is selected for the fluid bodies 38.

While certain specific embodiments of the invention have been described and illustrated by way of example, it will now be apparent to those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed and sought to be protected by Letters Patent of the United States is:

1. An electrical receptacle comprising block means of insulation material, said block means having a plurality of substantially cylindrical cavities therein, a plurality of cylindrical electrically conductive tubes disposed in the respective cavities and substantially completely filling the cavities, each tube having a closed and an open end, said block means having a plurality of spaced passages therein corresponding to the number of said cavities and extending from the open ends of the respective tubes to the exterior of the block means, a body of liquid metal disposed in each of the tubes, the cross sectionalarea of each of the passages being less than the cross sectional area of the open end of each tube so that the liquid metal is prevented by surface tension from flowing through said passages if the block means is turned to invert the tubes, and a plurality of electric conductors connected to the closed ends of the tubes, said conductors being out of contact with said liquid metal to prevent contamination thereof by material of the conductors.

2. An electrical receptacle comprising block means of insulation material, said block means having a plurality of substantially cylindrical cavities therein, a plurality of cylindrical electrically conductive tubes disposed in the respective cavities and substantially completely filling the cavities, each tube having a closed and an open end, said block means having a plurality of spaced passages therein corresponding to the number of said cavities and extending from the open ends of the respective tubes to the exterior of the block means, a body of liquid metal disposed in each of the tubes, the cross sectional area of each of the passages being less than the cross sectional area of the open end of each ltube so that the liquid metal is prevented by surface tension from flowing through said passages if the block means is turned to invert the tubes, and a plurality of electric conductors connected to the closed ends of the tubes, said conductors being out of contact with said liquid metal to prevent contamination thereof by material of the conductors, the closed ends of the tubes extending out of the block means so that the connections of the conductors thereto are external of the block means.

3. A connector comprising an interfitting plug and a receptacle, said plug comprising first block means of insulation material carrying a plurality of exposed metal prongs, said receptacle comprising second block means of insulation material having a plurality of substantially cylindrical cavities therein, a plurality of cylindrical electrically conductive tubes disposed in the respective cavities and substantially completely filling the cavities, each tube having a closed and an open end, said second block means having a plurality of spaced passages therein corresponding to the number of said vcavities and extending from the open ends of the respective tubes to the exterior of the second block means, ya body of liquid metal disposed in each of the tubes, the cross sectional area of each of the passages being less than the cross sectional area of the open end of each tube so that the liquid metal is prevented by surface tension from fiowing through said passages should the second block means be turned to invert the tubes, and a plurality of electric conductors connected to the closed ends of the tubes, said conductors being out of contact with the liquid metal to prevent contamination thereof by material of the conductors, said prongs extending through said passages into the bodies of liquid metal, the metal of said prongs being unwettable by said liquid metal.

4. A connector comprising an intertitting plug and a receptacle, said plug comprising first block means of insulation material carrying a plurality of exposed metal prongs, said receptacle comprising second block means of insulation material having a plurality of substantially cylindrical cavities therein, a plurality of cylindrical electrically conductive tubes disposed in the respective cavities and substantially completely iilling the cavities, each tube havinga closed and an open end, said second block means having a plurality of spaced passages therein corresponding to the number of said cavities and extending from the open ends of the respective tubes to the exterior of the second block means, a body of liquid metal disposed in each of the tubes, the cross sectional area of each of the passages being less than the cross sectional area of the open end of each tube so that the liquid metal is prevented by surface tension from ilowing through said passages should the second block means be turned to invert the tubes, and a plurality of electric conductors connected to the closed ends 0f the tubes, said conductors being out of contact with the liquid metal to prevent contamination thereof by material of the conductors, said prongs extending through said passages into the bodies of liquid metal, the metal of said prongs being unwettable by said liquid metal, the closed ends of the tubes extending out of the second block means so that the connections of the conductors thereto are external of the second block means.

5. An electrical receptacle comprising block means of insulation material, said block means having a plurality of substantially cylindrical cavitiestherein, a plurality of electrically conductive tubes disposed in the respective cavities and substantially completely filling thel cavities, each tube'having a closed andan open end, said block means having a plurality of spaced passages therein corresponding to the vvnumber of said cavities and extending from the open ends of the respective tubes to the exterior of the block means, a body of liquid metal disposed in each of the tubes, the cross sectional area of each of the passages being less than the cross sectional area of the open end of each tube so that the liquid metal is prevented by surface tension from liowing through said passages if the block means is turned to invert the tubes, the closed ends of the tubes extending out of the block means so that conductors may be connected thereto.

6. A connector comprising an intertting plug and a receptacle, said plug comprising iirst block means of insulation material carrying a plurality of exposed metal prongs, said receptacle comprising second block means of insulation material having a plurality of substantially cylindrical cavities therein, a plurality of cylindrical electrically conductive tubes disposed in the respective cavities and substantially completely filling the cavities, each tube having a closed and an open end, said second block means having a plurality of spaced passages therein'corresponding to the number of said cavities and extending from the open ends of the respective tubes to the exterior of the second block means, a body of liquid metal disposed in each of the tubes, the cross sectional area of each of the passages being less than the cross sectional area of the open end of each tube so that the liquid metal is prevented by surface tension from ilowing through said passages should the second block means be turned to invert the tubes, and a plurality of electric conductors connected to the closed ends of the tubes, said conductors being out of contact withy the liquid metal to prevent contamination thereof by material of the conductors, said prongs extending through said passages into the bodies of liquid metal, the metal of said prongs being unwettablc bytsaid liquid metal, there being direct electrical continuity between the prongs and conductors through the body of liquid metal and bodies of liquid metal and the tubes, said electrical continuity being maintained in all positions of the intertted plug and receptacle.

7. An electrical receptacle comprising block means of insulation material, said block means having a plurality of substantially cylindrical cavities therein, a plurality of cylindrical electrically conductive tubes disposed in the respective cavities and substantially completely filling the cavities, each tube having a closed and an open end, said block means having a plurality of spaced passages therein corresponding to the number of said cavities and extending from the open ends of the tubes to the exterior of the block means, a body of liquid metal disposed in each of the tubes, the cross sectional area of each of the passages being less than the cross sectional area of the open end of each tube so that the liquid metal is prevented by surface tension from flowing through said passages if the block means is turned to invert the tubes, and a plurality of electric conductors connected to the closed ends of the tubes, said conductors being out of contact with said liquid metal to prevent contamination thereof by material of the conductors, said block means being formed of two separable sections to facilitate disposition of the tubes in the cavities.

8. An electrical receptacle comprising block means of insulation material, said block means having at least one substantially cylindrical cavity therein, a cylindrical walled electrically conductive tube disposed in and substantially completely iilling said cavity, said tube having a closed and an open end, said block means having a passage therein extending from the open end of the tube to the exterior of the block means, a body of liquid metal disposed in the tube, the closed end of the tube being imperforate and leak-proof, and an electric conductor connected to the exterior of the tube so that the conductor is out of direct contact with the liquid metal while being in direct electric circuittherewith through the tube, said circuit being continuous in all positions of said block means.

9. An electrical receptacle comprising block means of insulation material, said block means having at least one substantially cylindrical cavity therein, a cylindrical Walled electrically` conductive tube disposed in and substantially completely filling said cavity, said tube having a closed and an open end, said block means having a passage therein extending from the open end of the tube to the exterior ofthe block means, an electrically conductive liquid body disposed in said tube, said body including an electrically conductive metal which extends throughout'said body, the closed end of the tube being imperforate and leak-proof, and an electric conductor connected to the exterior of the tube so that the cony ductor is out of direct contact Vwith said body while being t in direct electric circuit therewith through the tube, said circuit being continuous in all positions of said block means. n

References Cited in the file of this patent UNITED STATES PATENTS

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