US 3559146 A
Description (OCR text may contain errors)
Jam 26, 1971 R. vggLToNEN 3,559,145
l v GIURRENT SUPPLY RAIL ARRANGENENT AND A CONNECTION PLUG Filedot. 25. 196s United States Patent Oice Patented Jan. 26, 11971 3,559,146 CURRENT SUPPLY RAIL ARRANGEMENT AND A CONNECTION PLUG Rainer Valtonen, Tapiola, Finland, assignor to i Oy Nokia AB, Helsinki, Finland Filed OctrZS, 1968, Ser. No. 770,658
Int. Cl. H01r 3/ 06 U.S. Cl. 339--14 2 Claims ABSTRACT OF THE DISCLOSURE A plug is provided with a plurality of contact fingers. The fingers are resiliently supported so as to be movable from a retracted position inside the plug body to an extended position to engage the conductors and the grounded lead of the plug. Eccentrics are supported in the plug body and are engageable with the fingers to selectively displace same. A knob is provided externally of the plug and is coupled with each of the eccentrics to simultaneously displace all of the eccentrics.
'The present invention relates to an electric current supply rail arrangement and connection plug for use therewith, particularly intended for lighting purposes and for small electrical motors, the rail being of the kind comprising a metal rail serving as a grounding lead and supporting structure and one or `more electric conductors fixed in the metal rail and insulated therefrom by one or more fastening strips of plastics material.
Such a current supply rail arrangement is suitable for display windows, exhibition rooms, laboratories etc. for conducting electric current to electrical apparatus and arrangements of small current requirements and which are attached to the wall or ceiling. The current is conducted from the supply rail by means of suitably adapted connecting plugs, which are attachable to the supply rail at any desired point along the rail.
Various supply rail constructions of this kind are known. In order to achieve a handy attachment of the current supply rail to a support it appeared heretofore to be of advantage to arrange the conductors within a hollow metal rail that serves as a supporting strucure. Such a rail must be of a very accurate shape allowing the attachment of the connecting plugs to be` made with great accuracy. In order that the connecting plugs at eachpoint make proper contact with the conductors, the plugs should be uniformly spaced from each other. In known constructions the shape of the insulating and fastening strips of plastics fitted into the metal rail has determined the distance of the conductors from each other. Because the manufacturer of plastics strips of accurate dimensions involves great difficulties it has been troublesome to ensure that the conductors be uniformly spaced from each other. p
The object of the invention is to attain a supply rail arrangement using a supporting construction of metal, which obviates the manufacturing difficulties in providing conductors which extend with sufficient accuracy at a constant distance from each other.
This object of the invention is achieved by a current supply rail of the aforesaid kind and which is characterized by the feature that the conductors are fitted in those edge portions of the plastics strip which rest against the metal rail and that the section of the strip between said edge portions is curved and resilient so as to force said edge portion to rest against the metal rail.
The advantage of the invention is that the accuracy of the mutual positions of the conductors is determined apart from the accuracy of the metal rail, and only by the exactness of the thickness of the plastics strip. In the manufacture of plastics strip it is easier to avoid variations in thickness than the variations in shape and width. By arranging the conductors in said edge portions, which rest against the metal rail when the plastic strip is mounted inside the rail, it is'possible to eliminate the influence of the variations in shape and width of the plastic strip on the mutual position of the conductors within the rail. The plastic strip can be made comparatively thin. The actual values of the variations in thickness of a thin plastic strip are insignificant. When a plastic strip fabricated according to the invention is mounted into a metal rail manufactured with sufficient exactness the object is achieved that the conductors extend with a satisfying accuracy at a constant distance from each other,
Some embodiments of the invention will tbe described with reference to the accompanying drawings, wherein:
FIG. 1 shows in section a single phase supply rail arrangement according to the invention;
FIG. 2 shows in section a three-phase supply rail arrangement;
FIGS. 3 and 4 show respectively an end-view and a Side-view of a three-phase supply rail arrangement with a connecting plug; and
FIG. 5 shows a connecting plug for a three-phase supply rail arrangement in a section taken along line A-A in FIG. 4.
FIG. 1 shows a metal rail 1 which can be made, for example, as an extruded aluminum rail, serving as a supporting element and as a protective grounding lead, together with an insulating and fastening strip 2, which can be constituted, for example, of PVC-plastics, supporting conductors 4 and 5 which can be copper wires having a circular or a fiat cross section. The curved part 10 of the plastic strip 2.is of such a length that the strip after having been mounted into position in the rail 1 is slightly stressed. The position of the conductor 4 fixed by the plastic strip 2 relative the metal rail 1 is determined by the thickness of the parts 6 and 7 of the plastic strip. Similarly, the position of the conductor 5 relative the metal rail 1 is determined by the thickness of parts 8 and 9 of the plastic strip.
FIG. 2 shows a supply rail arrangement for a three phase system. This includes in addition to -the plastic strip 2 another similar plastic strip 2' supporting conductors 11 and 12. In this case the conductors 4, 11 and 12 are coupled in a suitable way to the wires of a three-phase circuit.
In FIGS. 3 and 4 is shown a connecting plug 13 attached to a supply rail. The connecting plug 13 is provided with contact fingers 14, 15, 16 and 17 for contacting the conductors 4, S, 11 and 12. The connecting plug is further provided with contact fingers 18 and 19 for contacting the metal rail 1in order to provide a protective grounding.
FIG. 5 shows the interior of the connecting plug 1 3 seen in section along line A-A in FIG. 4. The contact finger 15, whcih is made of a comparatively hard spring materila, e.g. bronze, is attached to the body of the connecting plug by a screw 21. By the action of an eccentric 20 journalled in the body of the plug the contact finger 15 is movable relative the body of the plug between a retracted position and a projecting position. The contact linger 15 is attached by means of a screw 21 to a wire of a conductor 22, which leads to a current consuming apparatus. The other contact fingers 14, 16, 17, 118v and 19, also of spring material, are in a corresponding manner attached to the body of the connecting plug and similarly connected to corresponding wires of the conductor 22. When the connecting plug 13 is to be attached to the current supply rail, the eccentric 20 and simultaneously the other eccentrics (not shown) acting on the other contact fingers are turned by means of a knob 23 (FIGS. 3 and 4) to such a position that the contact fingers are retracted allowing the connecting plug to be easily attached to the supply rail. The various eccentrics are of such shapes that, when the connecting plug is attached to the supply rail and the knob 23 is turned to move the contact fingers 14-19 to their contacting positions, the grounding contact fingers 18 and 19 are first brought in contact with the metal rail 1 before the other contact fingers 14-17 are brought in contact with their respective conductors 4, 5, 11 and 12, in order to achieve the protective grounding of the consumer apparatus before said apparatus is connected to the circuit.
The drawings and the descriptions thereto are only intended to exemplify the idea of the invention. As to details the connecting plug and the current supply rail arrangement can, within the scope of the claims, deviate to a certain extent from the embodiments depicted.
What I claim is:
1. A connection plug for a current supply rail assembly including a metal rail, and at least one current conductor supported by said metal rail, said current supply rail constituting a grounding lead, said plug comprising a hollow body, a plurality of contact fingers resiliently supported in said hollow body, said fingers being engageable at least one with one of each of the conductors and at least another with the grounded metal rail, eccentric means engageable one with one of each of said fingers to displace said fingers respectively from a retracted position internally of said hollow body to an extended position projecting externally of said hollow body to contact respectively the conductors and the grounded metal rail, and single control means operatively associated with each of said eccentric means to simutaneously displace each of said eccentric means.
2. A connection plug as claimed in claim 1 wherein said contact fingers are each operatively associated, one with one of each of said eccentric means, such that said control means is operable to displace said eccentric means simultaneously, with the contact finger, being engageable with said grounded metal rail, contacting said metal rail before the contact finger, being engageable with the conductor, contacts the conductor.
References Cited UNITED STATES PATENTS 3,503,032 3/1970 Routh et al. 339-14 3,181,102 4/1965 Fehr 339-21 3,295,093 12/1966 Neumann et al. 339-21 MARVIN A. CHAMPION, Primary Examiner R. A. HAFER, Assistant Examiner U.S. C1. X.R.