US 3386069 A
Abstract available in
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Description (OCR text may contain errors)
May 28 1958 E. A. r-:RlKssoN 3,386,069
ELECTRICAL CONNECTORS Filed Sept. 9, 1965 2 Sheets-Sheet 1 zNVENToR. EEA/57' .4. Eem/ssen l I l l l| A QE/ d A n 7 5 6 5 4 m .d l 4 5 8 o w .m 9 8 889% a/ w U m United States Patent O 3,386,069 ELECTRICAL CQNNECTORS Ernst A. Eriksson, 41 Preston Road, Lexington, Mass. 02173 Filed Sept. 9, 1965, Ser. No. 486,066 6 Claims. (Cl. 339-7) ABSTRACT F THE DISCLOSURE An electrical connector having a pair of electrical contacts, one being rotatable and having a surface matching a path of revolution concentric with the axis of rotation thereof, and a resilient pack of iilamentary conducting material in electrical connection with said contacts, said pack having its surface, in contact with the surface of said one contact, matching the surface of said one contact.
This invention relates to new and improved means for establishing electrical contact between members movable relative to each other, especially relatively rotatable members.
The existing counterparts to the invention are conventional collector rings or slip-rings and their brushholders. Their general installation can become quite massive and inconvenient, requiring considerable care and maintenance particularly due to oxidation and rapid wearing of the contact surfaces and being vulnerable because of their awkward spacedemanding conguration.
The novel device of the invention will perform as well as or better than any conventional device while at the same time providing a connector that is simpler, more compact, maintenance-free and convenient to install thereby affording greater equipment desi-gn flexibility. It is arc-proof, totally enclosed, has extended contact with a mating conductive surface for enormously greater current capacity with small size, and will operate at high speeds, create little or no electrical noise and has long wearing characteristics.
The invention features the use of a resilient pack of iilarnentary conducting material in a cavity that exposes a surface of revolution of the pack to a mating surface of revolution of a movable electrical contact. `Both the movable Contact and another electrical contact that engages another portion of the pack are connected to members .movable with respect to each other, thereby providing an unbroken electrical connection between them. The mating surfaces of revolution are preferably 360 closed surfaces and may be cylindrical about a central axis or in the form of parallel engaging rings about a central axis. In one form of the invention such surfaces cornprise surfaces of revolution described by a curved line revolved about an axis and are preferably spherical. The invention contemplates multi-circuit units with a pack and mating conducting surface supplied for each circuit as well as universal joint type relatively movable contacts.
Other objects, features and advantages will appear from the following description of presently preferred embodiments of the invention, taken together with the annexed drawings, in which:
FIG. 1 is a vertical sectional View of a spindle type ICC movable rotary heads having cylindrical mating surfaces;4
FiG. 2 is a cross-sectional view on line 2-2 of FlG. l;
FIG. 3 is an elevation, partially in section, of a modication employing a collar type arrangement of a rotary connector of the invention surrounding a shaft;
FIG. 4 is a vertical sectional view of a further modilication comprising a spindle type rotary connector in which the mating surfaces of revolution lie in vertically spaced horizontal planes;
FIG. 5 is an elevation of a spindle type rotary connector similar to that of FIG. 1 but Iwith three instead of only two circuits;
FIG. 6 is a vertical sectional view of a still further modified rotary connecter for coaxial conductors, exible or rigid, rotatable relative to each other;
FIG. 7 is an elevation partially in section of a universal joint type connector useful in connecting a rotatable coaxial conductor to stationary members with a universal joint feature; and
FIG. 8 is a view on line 3 8 of FIG. 7.
Referring now rst to FIG. 1, it should be noted that all parts except nuts, bolts and screws are cylindrical about the central, vertical axis, as indicated in FIG. 2.
The body of the rotary connector shown in FIG. 1 is generally designated by the numeral 1G. The two rotary heads are 11 and 12.
The body 1G of the rotary connector comprises electrically insulating base piece 13, electrically conducting piece 14, insulating piece i5', conducting piece 16, insulating piece 17 and conducting piece 13. Keeping all of the pieces except piece 13 of the body 10 together is the conducting nut and bolt 19.
Fitting onto piece 1-5 of the body 19 is an insulating cap 20. Piece 13 is secured to piece 18 by conducting screw 21 and lock nut 22 and to piece 14 by conducting screw 23 and lock nut 24.
The base 13 has mounting roles 25 and a hole 26 to allow adjustment of nut and bolt 19.
The body 19 is designed to be mounted on a support which may be stationary or rotatable. The outer rim of piece 17 is meant to keep rotary heads 11 and 12 in place. Piece 17 also acts to separate the rotary heads, both mechanically and electrically.
yBecause the rotary heads 11 and 12 are substantially identical, only head 11 will be described in detail.
The principal member making up the head 11 is the insulating retaining piece 27. Conducting piece 28 is press tted therein and connected to conducting screw 29 and nuts 39 and 31. Filling the cavity formed by pieces 27 and 28, which together form a holder open at one side, and piece 16, is the conductive pack 32. This pack is a mass of loosely-woven resilient copper, bronze or aluminum cloth of interconnected strands which conducts electricity and has a desirable springback characteristic in its packed attitude, insuring near contact at all times.
In operation, an electrical connection is made to terminal screw 29. With the aid of piece 28 electrical contact is continued to the conductive pack 32. Whether actually rotating or not, the conductive pack makes continuous electrical contact with the outer cylindrical surface of member 16, secured to the stationary body 10. The electrical path continues from piece 16, conducting nut and bolt `19, piece 14 to terminal 23, to which an outside connection may be made. Thus a good electrical circuit is established between terminal 29, rotatable with respect to the body 10, and terminal 23, mounted on the body 10. The construction and mode of operative of rotary head 12 is the same except that the electrical path is along piece 18 to terminal 21. This electrical path is insulated from that associated with rotary head 11. Meclranically, the two rotary heads can rotate with respect to each as well as to the base, if desired, and even in opposite directions.
FIG. 3 illustrates an embodiment of `the rotary connector of the invention which comprises a collar, one part 41 of which may rotate independently of a shaft 40 on which it is tted, the other part 42 of which is secured to and rotates with the shaft 40. In FiG. 3 tall pieces except nuts, screws and bolts are cylindrical and concentric about the central, horizontal shaft axis.
The principal member of part 42 is an electrically insulating piece 43, secured to the shaft 40 by a screw 44. The ring 45 maintains the desired relationship between parts 41 and 42. The member 43 forms two cavities, the outer one of which contains electrically conducting piece 46 in conductive engagement with conducting headless screw 47 carrying lock nut 48 and connecting nut 49. This cavity contains a conductive pack 50 of the kind described in connection with FIG. l.
The principal member of part 41 is insulating piece 51, rotatable with respect to the shaft 40. Arranged opposite piece 46 of part 42, conducting ring 55 is bonded within the cavity. Headless screw 52, lock nut 53 and connecting nut 54 provide an external electrical terminal `for the ring 55.
Also within the members 41 and 42 is a similar inner circuit havin-g conducting terminal screw 56, conducting piece 57, pack 58, conducting piece 59 and conducting terminal screw 60.
In operation, pack 50 provides an electrically conductive path between parts 46 and 55 which may move relative to each other. This outer circuit is completed between the external terminals 47 and 52; the other, inner, electrical circuit is similarly completed through terminal lS6, piece 57, pack 58, piece 59 and terminal 60. In this ernbodiment, terminal screws 52 and 56 are mounted on the same insulating piece 51, and terminal screws 47 and 60 mounted on the same piece I43, so that terminals 52 and 56 cannot 4move relative to each other and neither can terminals 46 and 60. The entire unit, if desired, can be secured to a stationary support by a bracket indicated by the dotted lines.
FIG. 4 illustrates a spindle type rotary connector similar to that shown in FIG. l except that in the former embodiment there were separate rotary heads capable of rotating relative to each other, each with its own terminal. In the present embodiment two terminals are connected to one rotary head.
In FIG. 4 Where again all pieces except nuts, screws and bolts are cylindrical and concentric about 'the central, vertical axis, the main body is designated generally by the numeral 70 and the rotary head by the numeral 71.
The body 70 comprises electrically insulating piece 72, electrically conducting piece 73, insulating piece 74 and conducting pieces 75 and 76. Keeping all of the body members except piece 72 together and joining the rotary head 71 to them is conducting nut and bolt 77.
An insulating cap piece 73 lits on the top of piece 76.
Securing piece 72 to piece 75 is conducting screw 79 with lock nut 80; securing piece 72 to piece 73 is conducting screw 81 with lock nut 82.
Similarly insulating member 83, like member 27 in FIG. 1, is provided with conductive liners 8S and 9:1 press tted into the two cavities which it provides. The conducting screw 85, with its nuts 86 and 37, in the upper section, penetrates through to the pack 84 and is connected to the liner 91 by soldering for example. During rotation the pack 84 keeps electrical contact with piece 76. The electrical path continues from piece 76 to nut and bolt 77, piece 73 and terminal screw 81 where an outside connection may be made. The lower section of the head has a similar path from screw 89 through pack 90 and piece 75 to terminal screw 79. Terminal screws 85 and 89 cannot move relative to each other because of their attachment to piece 83.
FIG. 5 is a side view in elevation of a spindle type rotary connector similar to the one shown in FIGS. 1 and 2 except that provision has been made for three electrical paths instead of two. The base is designated by the numeral 100. The three rotary heads are designated 101, 102 and 103, The screws, or outside terminals, associated with these rotary heads are designated 104, 105 and 106, respectively. The screw terminals 107, 1108 and 109 in the base are each the terminus of an electrical path associated with each of the rotary terminals 101, 102 and 103. Which base terminal is associated with a rotary terminal depends, ot course, on the internal structure selected which is essentially similar to that of FIGS. 1 and 2 tand for that reason has not been repeated.
FIG. 6 illustrates a rotary connector making an electrical connection between two coaxial conductors, rigid or llexible, that may rotate relative to each other.
The upper coaxial conductor is designated generally as 110, the lower as 111 and the connector as 112. The inner conductor 113 of cable 110 is centered within the insulating portion 114 and the outer conducting sheath I115. Corresponding parts of cable 111 are designated as 116, 117 and 113 respectively.
All pieces of the connector are cylindrical and concentric about a central, vertical axis.
The connector 112 is composed of electrically conducting piece '119 with threads 120, electrically insulating pieces `121 and 122, conducting piece 123 and insulating piece 124 with threads 125 to match those of piece 119. The cavity formed by pieces 121 and 122 is filled with a conductive pack 126 of the kind previously described, and the cavity formed by piece 119 and pieces 121 and 122 by a conductive pack designated `127.
Each coaxial conductor has been cut perpendicularly to its main axis except for the inner conductor 113 or 116 which extends beyond.
In operation, both conductor sheaths and 118 extend into the cavity formed by piece 119. There they both contact the conductive pack 127 which surrounds them. Inner conductor 113 extends past-piece 122 and inner conductor 116 extends past part of piece 121 into the cavity formed by pieces 121 and 122 where they both con. tact conductive pack 126 which similarly surrounds them. As inner conductors 113 and 116 rotate with respect to each other they continue to make electrical contact through the pack 126. The same is true of conductive pack 127 and outer conductors 115 and 118.
FIGS. 7 and 8 illustrate `a universal joint type application of the novel conductive pack effect. Not only full rotation but any movement in a 75 conical area is allowed by this embodiment.
A coaxial conductor is designated generally as 130. The connector is designated by the numeral 131. The conductor 130 has an inner conductor 132 centered within an insulating portion 133 and a conducting sheath 134.
All pieces of the connector except nuts, screws and bolts are concentric about a central vertical axis.
Electrically conducting piece 135, spherically shaped, grasps the conductor 130 and moves with it relative to the adjacent parts of the connector 131. The conductor 130 is cut perpendicularly to its axis and extends just past the outer portion of the connector 131 except for the inner conductor 132 which continues in until it is connected to spherical inner conducting piece 136. Piece 136 also moves with respect to the adjacent parts of the connector 131.
The remaining pieces are all joined together and form the balance of the connector 131. None of these pieces may move relative to each other except the conductive packs 137 and 138.
The upper portion of the connector 131 is insulating piece 139 with threads 140. The lower portion is insulating piece 141 with threads 142 to match those of piece 139. Conducting bolt 143 with lock nut 144 and contact ring 145 and terminal connecting nut 146 provide an electrical path from the outside to the annular conductive pack 138 (FIG. 8).
Insulating piece 147 contains the inside assembly. It is cut in half along the plane of the sectional view and joined with the aid of bolts (not shown) through holes 148. Contained within the upper portion of piece 147 is spherical conducting piece 136 and a conductive pack 137. Conducting bolt 149 provides the eletcrical connection from pack 137 to the outside. A terminal nut 150 aids outside connection.
The bottom protruding portion of piece 147 is threaded so that it may be securely fastened by nut 151.
'In operation, even while piece 136 may move relative to the connector 131 electrical contact with the conductive pack 137 continues and through the pack to the bolt 149 providing an outside terminal. The same is true of piece 135, pack 138 and bolt 143.
The uses which may be made of various forms of the invention are too numerous to list and only some of them will be referred to, it being understood that those skilled in the electrical and electronics arts will undoubtedly nd the invention useful for many additional purposes. In industry there are innumerable systems requiring the transmission of current or electrical signals between a nonmoving and a moving member or between two moving members, usually involving a rotating system. The invention makes possible such transmission eiectively while at the same time eliminating interference from intermittent or irregular contact which is common to many known systems and it also .prevents escape of signals and entry of unwanted signals into the system. Examples include radar antenna Systems; missile guidance equipment; manned centrifuges used in the space program; scanning devices; A.C. electric motors of all sizes, kinds and shapes; directional finders; probes; Oscilloscopes; controls; r.p.m. read-out devices, and so on. The connector is of course non-arcing and hence explosion proof.
Another large eld of use is in the transmission between relatively movable members or systems of high power utilizing either high currents, high voltage, or both. Examples include: pantagraph operations (i.e. positioning, etc.); mobile apple picker units; electric cable reels; heated rolls (for calendaring, etc.); moving illuminated signs; machine tools; moving amusement park equipment (i.e. ferris wheels and carousels); moving searchlights and beacons, to name but a few.
In the iield of home appliances the potential uses are virtually unlimited since the invention makes possible the much sought-after completely relaxed strain-free attitude of connectors, cable cords and connections to moving or portable appliances so as to prolong life and eliminate frequent replacement or repair and the danger from frayed or broken electrical cords. Some include: power operated hand tools of all kinds (drills, saws, etc.); electric irons, vacuum cleaners, blenders, cooking utensils, etc.; telephone hand sets; laboratory equipment and all kinds of test equipment.
In the eld of coaxial conductors, particularly those of a heavy nature, subject to twisting, torque may be eliminated by the insertion in the system of a connector of the type shown in FIG. 6. Where 90 elbows are required subject to rotation or twisting an adaption of the embodiment of FIGS. 7 and 8 may be advantageously employed. Universal joints of an electro-mechanical nature likewise form a natural field of exploitation for the same embodiment, whether the movement be oscillating, rotational, or conical, individually or in any combination.
Properly oriented with respect to the force applied the novel connector will withstand infinitely greater centrifugal or G yforces than conventional slip rings and brushes since the force will only serve to produce better rather than poorer contact by compacting the material of the conductor pack against the 360 mating contacting surface. Such forces tend to ing the contacts apart in conventional configurations, rather than together, as is well known.
Another advantage inherent in connectors employing the invention is the small voltage drop across the moving contacts because of the large volume of conductive material present and the 360 contact. This is an important consideration where sensitive devices are being used or where maximum power must be transmitted (i.e. with minimum loss). As applied to heated equipment, this is also true, for the new connector will not suffer loss of conductance with increased temperature as is true of conventional slip rings and brushes. Nor can the connector of the invention deteriorate as to conductivity due to wear or accumulation of dirt or loss of any spring tension as is commonly experienced with conventional equipment.
I have herein attempted to set forth the best mode contemplated by me for carrying out the invention. Modifications, changes, and additional uses will no doubt occur to those skilled in the art and it is not intended that the scope of the invention be limited by the specific embodiments shown and described or the specific end uses enumerated, but only by the proper scope of the appended claims.
1. In a rotatable electrical member having a cavity and a pair of electrical contacts, each of said contacts having a surface exposed to said cavity, one said contact rotatable in said member and the said surface of said one contact matching a path of revolution concentric with an axis of rotation of said one contact, that improvement comprising:
a resilient pack of interconnected loosely woven strands of tilamentary conducting material conned within said cavity in electrical contact with said surface of said one contact, said pack having one pack surface, adjacent and in contact with said one contact, matching said path of revolution and said surface of said one contact.
2. The improvement claimed in claim 1 in which said one contact and said pack surfaces are endless, closed surfaces.
3. The improvement claimed in claim 2 in which said one contact and said pack surfaces are cylindrical about a longitudinal axis of rotation.
4. The improvement claimed in claim 2 in which said one Contact and said pack surfaces are radially extending, annular rings about a longitudinal axis of rotation.
5. The improvement claimed in claim 2 in which said one contact and said pack surfaces are segments of spheres about the point of intersection of a plurality of axes of rotation.
6. In a multi-circuit rotatable electrical member having a plurality of cavities and a like number of pairs of electrical contacts, the contacts of each pair each having a surface exposed to one of said cavities, one said contact of each pair rotatable in said member, and said surface of said one contact of each pair matching a path of revolution concentric with an axis of rotation of said one contact, that improvement comprising:
a resilient pack of interconnected loosely woven strands of lamentary conducting material confined within each said cavity in electrical contact with said surfaces exposed to said cavity, each said pack having one surface, adjacent and in Contact with said one contact in said cavity, matching said path of revolu- 7 8 tion and said surface of said one contact in said 2,808,574 10/ 1957 Kelly 339-8 cavity. 2,837,723 6/1958 Krantz et al 339-5 3,105,728 10/1963 Seeloi 339-5 References Cmd 3,195,094 7/1965 Mohr 339-8 UNTTED STATES PATENTS 5 FO PA E S 1,762,422 6/1930 Rohrdanz 339-8 REIGN NT 2,173,325 6/1939 Alexander 339-5 302,012 12/1928 Great Brltam. 2,387,015 10/1945 Gilbertson 339-8 562,438 5/1957 Italy 2,433,938 1/1948 Varner 339-5 519933 8/1950 Rouault 339 7 X 10 MARVIN A. CHAMPION, Pl'lmary Examiner.
2,652,546 9/ 195 3 Chrstner 339-7 P. TEITELBAUM, Assistant Examiner.