US2883635A - Electrical coil and terminal assembly - Google Patents

Description

April 21, 1959 J. H. CLARK, JR

ELECTRICAL con. AND TERMINAL ASSEMBLY Filed July 19, 1956 [fit entofi: a/se wk H C/arvt, Jr;

2% Hlsflttormsy United States Patent 2,883,635 ELECTRICAL COIL AND TERMINAL SEN [ELY Joseph H. Clark, Jr., Fort Wayne, Ind., assignor to General Electric Company, a corporation of New York Application July 19, 1956, Serial No. 598,852 Claims. (Cl. 336-192) This invention relates to electrical terminal assemblies, and more particularly to terminal assemblies of the type commonly used on coils for electrical devices such as small transformers.

In the past, many small transformer coils have had their external electrical leads connected to the coil conductors in the manner shown in Patent 2,184,272 to H. L. Driftmeyer, assigned to the assignee of this application. In that construction, the coil conductor ends or tap leads were brought out and laid on top of the coil. Here they were connected to the external leads which were anchored to the coil by pressure sensitive tape. An outer insulating wrapper surrounded the entire periphery of the coil, including the external leads, to complete the assembly. In that construction, the external leads amounted to protuberances on the top of the coil and voids resulted between the external leads, the coil and the outer wrapper. Further, that construction involved a somewhat expensive hand assembly operation.

Coils of the type herein considered are generally impregnated with suitable varnish, encapsulated with suitable encapsulating material, or housed in an enclosing case which is filled with potting compound. It has been found that the voids around the external leads of coils having the construction of the aforementioned Driftmeyer patent may not be completely filled in the impregnation, encapsulation or potting operation. When such coils are used for relatively high voltage purposes, it has further been found that these voids or air pockets adjacent conductors having a high potential permit a corona discharge which deteriorates the insulation of the coil and causes premature failures. It is therefore desirable to provide a terminal arrangement for a coil which will permit connecting external leads to the coil conductors without voids and the resultant corona discharge, and it is further desirable that such an assembly be simple and readily assembled.

It is, therefore, an object of this invention to provide an improved electrical terminal assembly.

Another object of this invention is to provide an improved electrical terminal assembly for coils which eliminates voids adjacent to the leads.

A further object of this invention is to provide an improved electrical terminal assembly which is simple and readily assembled on a coil.

A further object of this invention is to provide an improved combination of electrical coil and terminal board.

Further objects and advantages of this invention will become apparent by reference to the following description and the accompanying drawing, and the features of novelty whichcharacterize this invention will be pointed out particularly in the claims annexed to and forming a part of this specification.

In accordance with one aspect of this invention, an elongated strip of relatively thin flexible sheet insulating material is provided having at least one recess formed in at least one longitudinal edge thereof. A terminal is provided having substantially the same thickness as the tions 6 of terminals strip and having a first portion which is seated in the recess in the strip flush with the top and bottom surfaces thereof. The terminal has another portion extending outwardly from the longitudinal edge of the strip for connecting electrical leads thereto. To complete the assembly, a pair of elongated strips of relatively thin sheet insulating material are respectively secured to the top and bottom surfaces of the recessed strip, these latter strips respectively covering at least a part of the terminal portion which is seated in the recess. The invention also includes an electrical coil having the improved terminal board around at least a portion thereof.

In the drawing,

Fig. l is a view in perspective showing the preferred embodiment of the improved terminal assembly of this invention and its method of assembly;

Fig. 2 is a cross sectional view of the improved terminal assembly of this invention taken along the line 2-2 of Fig. 1;

Fig. 3 is a view in a coil incorporating Fig. 1;

Fig. 4 is a fragmentary view in perspective, partly broken away, of the transformer coil of Fig. 3;

Fig. 5 is a fragmentary view showing that the improved terminal assembly of Fig. 1 may be constructed with the terminals on only one longitudinal edge;

Fig. 6 is a fragmentary view showing a modified form of the terminal;

Fig. 7 is a view of a terminal slightly modified from that shown in Fig. 6;

Fig. 8 is another fragmentary view showing a further modified form of terminal; and

Fig. 9 is yet another fragmentary view showing a still further modified form of terminal in accordance with my invention.

Referring now to Figs. 1 and 2, the improved terminal assembly 1 of my invention is formed of an elongated strip of relatively thin flexible sheet insulating material 2 having a plurality of spaced-apart, dove-tail shaped openings 3 respectively formed in its longitudinal edges 4. A plurality of terminals 5 are provided having substantially the same thickness as strip 2, as best viewed in Fig. 2. Terminals 5 each have a dove-tail shaped portion 6 having a configuration corresponding to dove-tail shaped recesses 3 in strip 2 and respectively seated therein so that the top and bottom surfaces of dove-tail shaped por- 5 are flush with the top and bottom Terminals 5 have portions 8 extendthe longitudinal edges 4 of strip 2. portions 8 may be provided with suit- 9 to facilitate the connection of electrical leads thereto, as will hereinafter be more fully described.

In order to complete the assembly, a pair of elongated strips of relatively thin sheet insulating material 7 are provided, these strips preferably being substantially as wide as strip 2 and being secured thereto so that they cover the top and bottom surfaces of the dove-tail shaped portions 6 of terminal 5. Strip 7 may be secured to sheet 2 by a suitable adhesive applied to strip 2, or may preferably be pressure sensitive tape of which many types are commercially available.

It will be seen in Fig. 1 that an elongated strip of terminals can be assembled and it will now be readily apparent that for use on a specific transformer coil, a section of this strip having the desired number of terminals can be cut off. Referring now to Figs. 3 and 4, there is shown a transformer 10 having a core 11 on which is mounted a coil 12 provided with the improved terminal strip of this invention. Here, coil 12 is formed of a suitable number of turns and layers of suitable magnet wire wound on spool 13 formed of insulating material. Terminal asperspective of a transformer having the improved terminal assembly of surfaces of strip 2.

ing outwardly from These projecting able openings sembly 1 is laid on the outer surface 14 of coil 12 and the coil conductor ends of terminals 5, as by soldering. External leads 16 are then connected to portions 8 of terminals 5, again as by soldering. An outer wrapper 17 of suitable sheet insulating material is then wound around the entire outer periphery of coil 12 thereby holding terminal assembly 1 in position. A strip 18 of pressure sensltlve tape anchors the free end of wrapper 17.

While the transformer coil 12 of Figs. 3 and 4 is shown as being provided with a single terminal assembly 1 having twelve terminals 5, it will be readily apparent that a larger or smaller number of terminals may be provided.

A transformer coil having six windings has been provided with the improved terminal assembly of this invention. The six coils are concentrically wound and comprise a primary coil for connection to a 115 volt source of alternating current and having 246 turns of .0142 inch wire in four layers, a high voltage secondary coil for providing 612 open circuit secondary volts and having 1,310 turns of .0031 inch wire in six layers, a 7.5 volt secondary coil having seventeen turns of .0142 wire in one layer, a 6.3 volt secondary coil having fourteen turns of .0359 inch wire in one layer, another 6.3 volt secondary coil having fourteen turns of .0380 inch wire in one layer, and a third 6.3 volt secondary coil having fourteen turns of .0253 inch wire in one layer. Each of these 15 are connected to portions 8 coils has two end conductors and thus a total of twelve terminals are required for connection to external leads. In this example, one terminal assembly 1 is provided having twelve terminals, six on each side, for connection to all the windings. This coil is 1% inches long, with two sides 2 inches wide and its other two sides 1 inches wide. The coil has a center window having two sides 1% inches wide and its other two sides inch wide. The insulating strip 2 of the terminal assembly 1 is therefore 1% inches wide corresponding to the 1% inches length of the coil and is .025 inch thick. These strips are formed of commercially available laminated kraft paper. Terminals 5 are formed of .025 inch thick cadmium plated brass with their portions 8 being A inch wide and inch long and their portions 6 belong inch long and 5 inch wide at their inner end. The terminals 5 are spaced /1 inch apart. The outer strips 7 are formed of commercially available pressure sensitive tape of six mils thickness. The outside wrapper 17 is formed of commercially available glass cloth of three mils thickness.

It will be noted that the terminal construction shown in Figs. 1 to 4 inclusive shows terminals 5 provided on both longitudinal edges 4 of insulating strip 2. It will be readily apparent that terminals 5 can if desired be provided in only one of the longitudinal edges of the strip 2 as illustrated in Fig. 5.

It will be seen that the dove-tail shaped configuration of portions 6 of terminals 5 and the mating configuration of recesses 3 of insulating strip 2 insure that the terminals 5 will not be pulled out of the strip 2 by tension on the external leads 14. It may be found, however, that where little or no tension is provided on the terminals 5 by the external leads 16, the force exerted by the outer strips 7 adhering to the inner portions of the terminals is sufiicient and that a rectangular terminal 19 seated in a rectangular recess 3 in strip 2, as shown in Fig. 6, may be utilized.

In the event that the external leads 16 tend to exert radial bending force on the terminals 5, a terminal 20 having the cross sectional configuration shown in Fig. 7

may be provided in lieu of the terminal 19 of Fig. 6.

Here, the terminal 20 has its longitudinal edges provided with a V-shaped cross section, as at 21, with its greatest transverse dimension between the longitudinal edges 21 being slightly greater than the nominal width ofrecess I 3. With this configuration, terminal 20 can be forced into recess 3 with the edges 21 cutting corresponding grooves in the insulating strip 2 thereby anchoring the terminal against radial bending forces.

Another variation of the terminal of Fig. 6 is shown in Fig. 8 in which terminal 22 is provided having recesses 23 formed in its inner portion thereby defining an enlarged portion 24 remote from the longitudinal edge 4 of strip 2. Strip 2 is, of course, provided with recess corresponding to the configuration of terminal 22.

' Referring now to Fig. 9, it will be seen that the terminal may be formed of square wire rather than bar stock as shown in the previous figures. Here, insulating strip 2 has an elongated recess 25 formed in its longitudinal edge 4, recess 25 having a portion 26 extending transversely of strip 2 and portions 27 extending in directions difierent from the direction of portion 26. Terminal 28 is formed of suitable square wire having its thickness substantially the same as the thickness of insulating strip 2 and having. an inner portion 29 conforming to and seated inrecess 25. Terminal 28 has an outer portion 30 with a suitable hook 31 formed on the end thereof for connecting external leads thereto.

It will be readily understood that the embodiments shown in Figs. 5 through 9 are, in common with the embodiments shown in Figs. 1 through 4 inclusive, characterized by having terminals with substantially the same thickness as the insulating strip 2, these terminals being seated in their corresponding recesses in the insulating strip 2 so that they are flush with the top and bottom of surfaces thereof. It will also be understood that the outer strips 7 on both sides of insulating strip 2 are provided in each of the embodiments of Figs. 5 through 9 inclusive. It will be readily understood in connection with all the figures of the drawing that the outer strips 7, while preferably having substantially the same width as the insulating strip 2, can be slightly narrower as long as they cover and engage a substantial part of the inner portion of the terminals.

It will now be readily apparent that this invention provides a terminal assembly in which the terminals are recessed in an insulating strip and, being of substantially the same thickness as the strip, voids and air pockets adjacent high potential conductors are eliminated.

While I have shown and described specific embodiments of this invention, further modifications and improvements will occur to those skilled in the art. I desire that it is understood therefore that this invention is not limited to the specific form shown and I intend in the appended claims to cover all modifications within the spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having at least one recess formed in at least one longitudinal edge thereof, a terminal having substantially the same thickness as said strip and having a first portion seated in said recess flush with the top and bottom surfaces of said strip, said terminal having a second portion extending outwardly from said longitudinal edge of said strip for connecting electrical leads thereto, and a pair of elongated strips of relatively thin sheet insulating material respectively secured to the top and bottom surfaces of said first-named strip and covering at least a part of said first portion of said terminal.

2. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having at least one recess formed in at least one longitudinal edge thereof, a terminal having substantially the same thickness as said strip and having a first portion seated in said recess with its top and bottom surfaces substantially flush with the top and bottom surfaces respectively of said strip, said terminal having a second portion extending outwardly from said longitudinal edge of said strip for connecting electrical leads thereto, and a pair of elongated strips of relatively thin substantially flush with the assaess sheet insulating material respectively secured to said top and bottom surfaces of said first-named strip and substantially covering said top and bottom surfaces of said first portion of said terminal.

3. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having at least one recess formed in at least one longitudinal edge thereof, a terminal having substantially the same thickness as said strip and having a first portion seated in said recess with its top and bottom surfaces top and bottom surfaces respectively of said strip, said terminal having a second portion extending outwardly from said longitudinal edge of said strip for connecting electrical leads thereto, and a pair of elongated strips of relatively thin pressure sensitive tape respectively secured to said top and bottom surfaces of said first-named strip and substantially covering said top and bottom surfaces of said first portion of said terminal.

4. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having a plurality of spaced apart recesses formed in each longitudinal edge thereof, a plurality of terminals each having substantially the same thickness as said strip, said terminals having first portions respectively seated surfaces substantially flush with the top and bottom surfaces respectively of said strip, said terminals having second portions extending outwardly from said longitudinal edges of said strip for connection of electrical leads thereto, and a pair of elongated strips of relatively pressure sensitive tape of substantially the same width as said first named strip respectively secured to said top and bottom surfaces of said first-named strip and covering said top'and bottom surfaces of said first portions of said terminals.

5. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having at least one dove-tail shaped recess formed in at least one longitudinal edge thereof, a terminal having substantially the same thickness as said strip and having a dove-tail shaped portion seated in said recess with its top and bottom surfaces substantially flush with the top and bottom surfaces respectively of said strip, said terminal having a second portion extending outwardly from said longitudinal edge of said strip for connecting electrical leads thereto, and a pair of elongated strips of relatively thin sheet insulating material respectively secured to said top and bottom surfaces of said firstnamed strip and substantially covering said top and bottom surfaces of said first portion of said terminal.

6. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having at least one substantially rectangular recess formed in at least one longitudinal edge thereof, a terminal having substantially the same thickness as said strip and having a substantially rectangilar portion seated in said recess with its top and bottom surfaces substantially flush with the top and bottom surfaces respectively of said strip, said terminal having a second portion extending outwardly from said longitudinal edge of said strip for connecting electrical leads thereto, and a pair of elongated strips of relatively thin sheet insulating material respectively secured to said top and bottom surfaces of said first-named strip and substantially covering said top and bottom surfaces of said first portion of said terminal.

7. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having at least one substantially rectangular in at least one longitudinal edge thereof, a terminal having substantially the same thickness as said strip and having a substantially rectangular portion seated in said recess with its top and bottom surfaces substantially flush with the top and bottom surfaces respectively of said strip, the longitudinal edges of said rectangular portion of said terminal respectively having a substantial V-shaped cross-section with the greatest transverse dimension between said longitudinal edges being greater than the nominal width of said recess said terminal having a second portion extending outwardly from said longitudinal edge of said strip for connecting electrical leads thereto, and a pair of elongated strips of relatively thin sheet insulating material respectively secured to said top and bottom surfaces of said first-named strip and substantially covering said top and bottom surfaces of said rectangular portion of said terminal.

8. An electrical terminal assembly comprising an elongated strip of relatively thin flexible sheet insulating material having at least one recess formed in at least one longitudinal edge thereof said recess having an enlarged portion remote from said longitudinal edge of said strip a terminal having substantially the same thickness as said strip and having a first portion with a configuration corresponding to said recess and seated therein flush with the top and bottom surfaces of said strip, said terminal having a second portion extending outwardly from said longitudinal edge of said strip for connecting electrical leads thereto, and a pair of elongated strips of relatively thin sheet insulating material respectively secured to said top and bottom surfaces of said first-named strip and substantially covering said top and bottom surfaces of said first portion of said terminal.

cured to said top and bottom surfaces of said first-named strip and substantially covering said first portion of said terminal.

References Cited in the file of this patent

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