US3146419A - Soldering terminal assembly and coil - Google Patents

Description

c. E. WARREN ETAL soLDERING TERMINAL ASSEMBLY AND con;

Filed April 27. 19Go Aug. 25, `1964` United States Patent 3,146,419 SOLDERING TERMINAL ASSEMBLY AND COIL Charles E. Warren and Charles F. McVoy, Jr., Danville,

Ill., assignors to General Electric Company, a corporation of New York Filed Apr. 27, 1960, Ser. No. 25,138 6 Claims. (Cl. 336-192) This invention relates to coils for inductive devices and more particularly to solder terminals used in conjunction with coils for inductive devices.

.In the design of inductive devices, such as ballast transformers, it is frequently necessary to provide suitable terminals for soldering the coil leads and taps with other internal and external leads of the ballast circuit. When the coil is a high voltage coil and thus wound with line wire, the terminal used in conjunction with such a coil must provide a means for eifectively joining the extremely fine wire in electrical contact with the larger sized wire used in connecting the various leads of a ballast circuit, such as the external leads connected to the fluorescent la-mp and to the power source.

As thesize of the Wire forming an electrical coil decreases, its mechanical strength decreases. Thus, it becomes 'important to provide a coil with a terminal to which all the connecting wires can be anchored firmly in f good electrical contact and to which soldered connections can be made without danger of burning the iine wire or the insulating paper. Further, such a terminal must be securely fastened to the coil body so that the terminal can serve as a strain relief connection for the line coil wire leads. In the event that one of the external leads is strained, this strain should not be imparted to the line coil wire leads but should be taken up by the core and coil assembly which can best withstand the strain.

Coil assemblies generally used in inductive devices,

such as ballast transformers, are comprised of a pluralityof layers of wire separated by a paper insulation interleaved between the layers of wire. The outer periphery of the coil assembly is also made up of paper insulation. Since design considerations require that the terminal assembly be attached to the outer periphery of the coil, it is desirable that the terminal pads of the terminal assembly be fabricated of a resilient insulating material, such as paper, in order to prevent the terminal from cutting and tearing the outer protective covering ofthe coil assemblyn. For the same reason, it is also desirable that the pocket terminals, which are generally formed of a metal, be effectively separated from the paper periphery of the coil by a resilient separating means.

Further, in core constructions of the type used for ballast transformers it is desirable that the transverse dimensions of the coil be kept at a minimum. Therefore, when a terminal assembly is attached to the outer periphery of a coil body, it should not appreciably increase the transverse dimensions of the coil assembly. In a ballast appartus, the transverse dimensions are critical because the ballast is generally concealed within a fixture. Fixture manufacturers require that the transverse dimensions of 'a ballast be maintained under specified dimensional limits. Since the terminal assembly must be necessarily connected to the outer periphery of the coil, preferably it should be so disposed on the periphery of the coil so as to have only a minimal effect on the transverse dimension.

` Cost considerations require that the terminal pads be preferably fabricated of a low cost insulating material, such as paper. Further, from a standpoint of manufacturing costs, it is desirable thatit be possible to solder all of the leads of the coil assemblies of an inductive device, such as aballast transformer, simultaneously in one operation which can be performed in a production line.

Accordingly, it is an object of the invention to provide an improved coil assembly having solder terminals in assembled relation therewith incorporating the desirable features set forth above.

Another object of the invention is to provide improved solder terminals which are adapted for connection to the outer periphery of a coil body and do not appreciably increase the transverse dimensions of a coil assembly.

It is a further object of the invention to provide an improved solder terminal for a coil assembly that will serve as a strain relief connection for fine coil wire leads connected therein.

A more specific object of the invention is to provide a terminal assembly that makes it possible to simultaneassembly having a terminal pad formed of two insulating layers defining a longitudinally extending section and a laterally extending section to which are attached a plurality of solder pocket terminals. The attaching portions of the pocket terminals are sandwiched between the two insulating layers so that one of the layers effectively separates and insulates the attaching portion from the paper covering of the coil body. Preferably, each pocket terminal is formed from a substantially rectangular elongated strip having two pairs of oppositely disposed outwardly extending arcuate portions formed on the outer edges of the strip, the pocket being formed by bending the strip to bring the pairs of arcuate portions in tangential relationship with each other. Also, the pocket terminal is formed with two oppositely disposed notches so that ne wire leads can be hooked on one of the notches and wrapped around the smooth, rounded portion formed on the pocket terminal by the arcuate portions.

In another aspect of the invention, the two insulating layers of the terminal pad are formed from a single sheet, pieferably a paper sheet of suitable thickness, cut out so that the first substantially T-shaped layer is formed as the second layer is formed by folding over two folder portions on the rst insulating layer to make-up a twolayered substantially T-shaped terminal pad between which the attaching portions of the pocket terminals are sandwiched.

The subject matter which we regard as our invention is set forth in the appended claims. The invention itself, however, together with further objects and advantages thereof may be understood by referring to the following description taken in connection with the accompanying drawings in which:

FIG. l is a view of the terminal assembly in accordance with the invention showing the insulating layers of the terminal pad unfolded;

FIG. 2 is a perspective view of a terminal assembly in accordance with the invention showing one of the insulating layer folder portions folded over and the other overlap portion partially folded over;

FIG. 3 is a top view of a pocket terminal illustrating how the terminal of the invention is formed from a metal strip;

FIG. 4 is a side View of the pocket terminal strip shown in FIG. 3;

FIG. 5 is a view in perspective, partially broken away,

illustrating the manner in which iine wire leads are wrapped around the pocket terminal;

FIG. 6 is a view in perspective, partially broken away, illustrating the improved terminal assembly in a core mounted in a conventional ballast core;

FIG. 7 is a perspective view illustrating how the pocket terminals of the invention as utilized in a ballast transformer are simultaneously soldered; and

FIG. 8 is a side view of a ballast apparatus having the case cut away to illustrate the interior disposition of the components after the ballast components are removed from the fixture and soldering pot shown in FIG. 7.

Referring now to the illustrated embodiment of the invention of FIG. 1, there is shown a terminal assembly y11 comprising a terminal pad 12, a pair of folder portions 13, 14 and four pocket terminals 15a, 15b, 15C, 15d having the attaching portions 16a, 1Gb, 16C, 16d and pocket portions 17a, 1711, 17e, 17d, respectively. The folder portions 13, 14 are folded about the axes 18, 19 to form a second insulating layer.

lAs shown in FIG. 2, one of the folder portions 13- is folded over so as to sandwich the attaching portions 16a, 16b of the pocket terminals 15a, 15b. The other folder portion 14 is partially unfolded -to illustrate how the two insulating layers of the invention are formed from a single sheet. When the folder portion 14 is folded over, it will be in an abutting relationship with folder portion 13 and will overlay the attaching portions 16C, 16d of pocket terminals 15C, 15d.

In the hereinafter described exemplication of the invention, the terminal pad 12 'shown in FIGS. l and 2 was cut of from craft paper .015 of an inch in thickness. It will be seen that when the folder portions 13, 14 are bent to overlay the attaching portions 16a, 1611, 16C, 16d, they serve as a protective and insulating covering. When terminal assembly 11 is attached to a coil body, the folder portions 13, 14 thereby prevent the sharp edges of the attaching portions 16a, 16h, 16C, V16a? from tearing the paper insulation of the coil body.

The pocket terminals 15a, 15b, 15C, 15d may be formed from a metallic strip, such as tinned steel. In FIGS. 3 and 4, we have illustrated a pocket terminal 15 before it is bent to form a pocket at a ninety degree angle with Vthe attaching portion. It will be seen that the pocket -terminal strip 15 is formed with two pairs of outwardly extending arcuate portions r21, 22 and 23, 24 formed in the side edges of the pocket terminal strip 15. Thus, a pocket is formed when the strip is bent along a transverse line intermediate the pairs of arcuate portions 21, 22 and 23, 24 so that they are brought into tangential relationship with each other to form a pocket in which ythe stripped ends of external leads and the coil leads are held in position before they are dipped in solder. A pair of notches 26, -27 are provided to facilitate bending of pocket portion I7. An attaching portion 1-6 is formed with a point 28 to fasten the attaching portion 16 to the terminal pad 12. The pocket terminal 15 may be attached to the terminal pad 12 by bending the point 28 after it has penetrated the terminal pad. It will be appreciated that a pocket terminal may be attached to a terminal pad by other fastening means well known in the art.

The fragmentary view of FIG. illustrates how fine wire leads 29, 35 are att-ached to a pocket terminal 15d. The line wire lead 29 is brought out from one side of a coil body 37. It will be seen that the fine wire lead 29 is -iirst hooked in the notches 26d, 27d and then wrapped around the arcuate portions 21d, 22d, 23d, 24d which present a smooth, rounded surface. Hooking the fine Wire lead 29 in the notches 26a', 27d results in the advantage that fine wire lead 29 is positioned against the terminal so that when the pocket terminal 15d is bent over on the terminal pad 11 after soldering, the fine wire 29 will not be ruptured. Y

Fine wire lead 35 is brought out from the front side of the coil, as seen in FIG. 5, and is hooked on notch 26C.

The fine wire lead is then wrapped around the arcuate portions 21C, 22C, 23e, 24C. Thus, it will be appreclated that the fine wire leads 29, 35 attached to the pocket terminals 15C, 15d are securely held in position and the coil body 37 can be handled before soldering in a production line type of operation Without disturbing the tine wire connections.

In FIG. 6, we have illustrated a perspective view show.- ing a broken off portion of a core and coil assembly 36 utilizing the terminal assembly 11 of the invention. The terminal assembly 11 is shown in xed assembled relation to coil body 37. The coil body 37 has a plurality of layers of relatively ne wire. Interleaved between the layers of wire are layers of paper 38. An external lead 39 and the tine Wire coil lead A29 are shown connected in the soldered pocket portion 17d of pocket terminal 15d. A second external lead 41 and the fine wire coil lead 35 are connected at the soldered pocket portion 17c of pocket 'Y terminal 15C.

The coil body 37 and its wound wire layers are disposed about a longitudinal axis (not shown) on a laminated magnetic core assembly 42, the laminations of which are held together by a clamp 43. It will ybe seen that the terminal assembly 11 has a substantially T-shaped configuration presenting a longitudinal section 44 and a transverse section 45 on which the pocket terminals 15C, 15d are attached. A strap 46 securely engages the longitudinal section 44 and serves to firmly anchor the terminal assembly 11 against the outer periphery of the coil f o riphery of the coil body 37, if tearing of the paper is to be prevented. Thus, in accordance with the invention, the insulating layer 31 is interposed between the attaching portions 16e, 16d of pocket terminals 15C, 15d and the periphery of the coil body 37. It will be seen that the pocket terminals as shown in FIG. 6 are dip 'soldered and are bent flat on top of insulating layer 32. By' bend-f ing the pocket terminals 15C, 15d and the others ove iii this manner, it will be seen that the transverse dimensions of the coil body 37 are not appreciably affected. Moe= over, this feature results in the advantage that a sturdy strain relief connection is provided so that any external force exerted upon an external lead will not be transmitted to the fine wire leads like the tap'29 brought out from the coil body 37.

In FIG. 7, we have shown an apparatus which illustrates how the terminal assemblies 11, '11 of the present invention make it possible to solder all connections of a core and coil assembly 36 simultaneously. For the purpose of making the solder connections, a Yspecial fixture 47 is provided with lead retaining springs 48, 219 to temporarily retain leads 50a, 5017, 50c 50d, 50e, 5W, 50g, 59h firmly in position until theyare soldered. A capacitor 51 is firmly held by the `x`ture 47 on top Vof a 'core and coil assembly 36, such a's is commonly used in a fluorescent lamp ballast.

When the fixture 47, the capacitor 51-and the core and coil assembly are assembled in this manner, it is possible to readily position the leads Stirn-50h, 50c, Sild, 50e,

Silf, 50g, 'Stili in theirrespective pocket terminals 15a, 15b, 15C, 15d and the terminals of terminal assembly 11', which are not seen in the view of FIG. 7. .It will be seen that the core and coil assembly 36 has a'pair of coils 37, 57, each coil having its termial assemblies .11, .11 attached in assembled relation thereto, as is more clearly seen in the side view'of FIG. `8.

Referring again to FIG. 7, the entire assembly comprising the fixture ,47, capacitor 51, and core and coil assembly 36 is positioned on a pair of-supports 53, 54 over a pot 55 containing solder 56. In the arrangement shown in FIG. 7, the solder contained in the individual molds 60a, 60h, 60C, 60d is brought up to the pocket terminals 15a, 15b, 15C, 15d by a vertically movable device 58 which may be mechanically actuated by a foot pedal or other means (not shown). Although the arrangement shown in FIG. 7 was found to be readily adaptable to production line operation, it will be appreciated that the terminal assemblies 11, 11 can also be soldered by lowering them into hot solder 56.

After the various leads are soldered in their terminal pockets, the leads 50a, Sib, 50c, 50d, 50e, 50j, 50g, 50h are disengaged from the retaining springs 48, 49 and the fixture 47 is removed. The soldered pocket terminals 15a, 15b, 15e, 15d may then be bent fiat on the outer insulating layer 32, as shown in FIG. 6. The capacitor 51 and core and coil assembly are now ready for placement in a ballast case 60, as shown in FIG. 8. When placed in the case 60, the terminal assemblies 11, 11 are on the top side of the coil bodies 37, 57. The capacitor 51 is disposed within the case 60 in an end-to-end relationship with the core and coil assembly 36.

Inv a ballast apparatus of the type illustrated in FIG. 8, the transverse dimensions are critical because it is necessary to conceal the ballast in a fixture. Consequently, xture manufacturers impose limitations on the transverse dimensions of the ballast case 60 which, of course, are determined by transverse dimensions of the components contained therein.

As shown in FIG. 8, the terminal assembly 11 is securely attached to the periphery of the coil body 37 by two straps 46, 61. Similarly, the terminal assembly 11 of coil body 57 is attached by the coil straps 62,63. A portion of one lead 34 is shown connected with the soldered pocket terminal 15d of terminal assembly 11 and also a portion of lead 64 is shown connected in the pocket terminal 65 of terminal assembly 11. The two coil bodies 37, 57 are disposed on the center leg of the core assembly 42 which is comprised of stacked laminations held together by clamps 43, 66. As is well known in the art, the coil and core assembly 36-and the capacitor 51 are secured in the ballast case 60 by a suitable potting compound, such as asphalt (not shown).

It will be appreciated that, as shown in FIG. 8, the thickness of the terminal assemblies 11, 11 are somewhat exaggerated. The actual thickness of the paper used in the practice of the invention was .015 of an inch. The thickness of the tinned strip steel used to fabricate the terminal pockets 15a, 15b, 15C, 15d was .0l of an inch. Thus, the over-all transverse thickness of the pocket portion of terminal pockets 15a, 15b, 15C, 15d was approximately .065 of an inch. It will be seen, therefore, that the terminal assemblies in accordance with the invention do not appreciably affect the over-all transverse dimensions of a coil body.

In the foregoing described exemplification of the invention, we have provided a terminal assembly which can be readily fabricated from inexpensive parts and can be easily attached to a coil body. Although in the illusf trative embodiment of this invention the terminal assembly is attached to the coil body by means of straps, it will be appreciated that the terminal pads can be attached to the coil body by means of glue or other suitable means.

The pocket terminal arrangement wherein the soldered pocket is bent flush with the terminal pad results in the advantage that the terminal serves as a strain relief type of connection for the purpose of relieving the fine core wire leads of any strains that might be inadvertently placed on the external leads. Further, the pockets formed by bringing the arcuate raised portions of the terminal strip in tangential relationship with each other, make it possible to place all of the leads in position in the terminal pocket prior to soldering and to handle the assembly without disturbing the relative position of the leads.

It will be understood that while we have described above a particular embodiment of the invention, it will be apparent that many modifications may be made without departing from the principle of the invention. It is to be understood, therefore, that we intend by appended claims to cover all such changes and modifications that would fall within the true spirit and scope of the invention.

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

l. A coil assembly comprising a plurality of external leads, a coil body having a plurality of layers of wire wound with reference to a longitudinal axis, said coil body having coil leads brought out from said coil body and having insulating material covering the outer layer of said body; a terminal pad having a first insulating layer and a second insulating layer, said second insulating layer superimposed on said first insulating layer, said insulating layers defining a first elongated section extending in the direction of said longitudinal axis and a second elongated section extending in a transverse direction; a plurality of solder pocket terminals, said pocket terminals having an attaching portion and a pocket portion, said external leads having ends thereof disposed in an axial direction in the pocket portions of said pocket terminals and soldered therewith, said attaching portion being fastened to one side of said first insulating layer on said second elongated section thereof and said pocket portion folded over on the other side of said first insulating layer so as to overlie said attaching portion; and means joining the superimposed insulating layers defining said first elongated section and said terminal pad in a fixed assembled relation with said coil body, said attaching portion being sandwiched between said first and second insulating layers and said first insulating layer being interposed between said attaching portion and said outer layer of the coil body.

2. A coil assembly comprising a coil body having a plurality of layers of wires, said layers of wires having insulating material interleaved between said layers and covering the outer layer of said coil body; a terminal pad having a first insulating layer and a second insulating layer formed of two folder portions to define an axially extending section and a transversely extending section; a plurality of solder pocket terminals formed with an attaching portion and a pocket portion for holding leads, said pocket terminals formed from a thin metal strip, each pocket terminal having two pairs of outwardly extending arcuate portions brought into tangential relationship by bending said strip thereby defining the pocket portion of the terminal, said attaching portion being fastened to the transversely extending section of said first layer on one side and said pocket portion folded over on the other side thereof so that said pocket portion overlies said attaching portion on the other side of said transversely extending section of said first layer to minimize the cross-sectional dimensions of the coil assembly; a plurality of external leads having their ends disposed in an axial direction in the pocket portions of said solder pocket terminals and soldered therewith, and means for strapping said axially extending section of the insulating layers to said coil body, said attaching portions of said plurality of solder pocket terminals being sandwiched between said first and second LayersE 3. A coil assembly comprising a plurality of external leads, a coil body having a plurality of layers of Wire, said coil body having coil leads brought out from said coil body and having insulating material covering the outer layer of said coil body; a terminal pad formed of a first insulating layer and a second insulating layer superimposed thereon, said first and second insulating layers defining a substantially T-shaped configuration; a plurality of solder pocket terminals formed with an attaching portion and a pocket portion, said external leads having ends disposed in an axial direction in the pocket portions of said solder pocket terminals and soldered therewith, said attaching portion being secured to said first insulating 'layer on one side, said pocket portion folded over on the. other side of said first insulating layer, and said attaching portion-'beingsandwiched Vbetween said rst yand second. kinsulating layers wherein said second layer is interposed between said attaching portion v'and said periphery of the coil body, and means for attaching said T-shaped insulating layers of said terminal pad in fixed assembled relation with `said coil body so '-that the folded pocket portions provide a strain relief connection for leads soldered yinsaid pocket portion.

4. The coil assembly set forth in claim 3 in which said insulating layers are fabricated from a paper sheet cut out so .that the second insulatinglayer is superimposed on the rst insulating layer by folding over two folder portions of the first insulating layer to form the substantially T- Vshaped configuration of the insulating layers.

5. A terminal assemblyfor attachment to a coil body and for connecting .the `coil leads with other leads, said assembly comprising: a substantially T-shaped terminal layer, said second insulating layer formed by folding over a Irst and second folder portion to define the T-shaped configuration, said "rst and second folder portions and said first insulating layer being fabricated from the same sheet of insulating material, a plurality-ofpocket terminals fastened to said 'first layer. on one side of said first layer, eachof said .pocket terminals having an attaching portion and a pocket portion, said attaching .portion being secured to .said first insulating layer of vsaidterminal pad on one side of said rst insulating layer, said pocketportion folded over the other side of said iirst insulating layer .to provide .a relatively iiat terminal assembly, said attaching `portion 'being sandwiched 'between said first and second insulating layers, andzsaid pluralityof pocket terminals formed from 20 pad having a iirst insulating layer and a second insulating 5 a thin strip of conductive material, each pocket terminal having two pairs of outwardly extending arcuate portions brought into tangential. relationship by bending said strip `thereby forming said pocket-portion of the terminals.

6. A terminal vassembly vfor attachmentto a coil body and for connecting the coilleads with external leads, said assembly comprising: a plurality ofi external leads, a terminalpadformed of'a first insulating layer and a second insulating layer superimposed thereon, said first Vand second insulating layersdening a substantially T- shaped configuration; a v.plurality of'solder pocket terminals formed with an .attaching portion and a pocket portion, said attachingportion beingfsecured to said first 'insulating layer on-one side, said'pocket portion folded over on the other `side of said iirstinsulating layer, said -solder pocket terminals formed from a thin strip of conductive material, each solder pocket terminal having at least two pairs of outwardly extendingarcuate side portions broughtoutinto tangential relationship by bend- -ing said strip to form saidpocket .portionQs'aid external leads having ends disposed in an axial .direction in the pocket portions and soldered thereto, `a plurality of coil leads `wrapped around'thepocket portions .and soldered thereto, and said .attaching rportion being sandwiched between said rst and second insulating layers whereby the 'folded pocket .portion of said solder pocketfterminals provide a strain relief connection for coil leadssoldered to said pocket portions.

References Cited in the ktile of this patent `UNITED.STATES PATENTS 2,529,653 -Epstein Nov. 14, 1950 2,533,483 Lesquadro Dec. 12, 1950 2,631,184 Sampson a Mar. 10, '1.953 2,722,671 Zerwes Nov. 1, 1955 2,883,635V `Clark Apr. '21, 1959 2,992,370 Laviana July-11, 1961

Claims (1)

1. A COIL ASSEMBLY COMPRISING A PLURALITY OF EXTERNAL LEADS, A COIL BODY HAVING A PLURALITY OF LAYERS OF WIRE WOUND WITH REFERENCE TO A LONGITUDINAL AXIS, SAID COIL BODY HAVING COIL LEADS BROUGHT OUT FROM SAID COIL BODY AND HAVING INSULATING MATERIAL COVERING THE OUTER LAYER OF SAID BODY; A TERMINAL PAD HAVING A FIRST INSULATING LAYER AND A SECOND INSULATING LAYER, SAID SECOND INSULATING LAYER SUPERIMPOSED ON SAID FIRST INSULATING LAYER, SAID INSULATING LAYERS DEFINING A FIRST ELONGATED SECTION EXTENDING IN THE DIRECTION OF SAID LONGITUDINAL AXIS AND A SECOND ELONGATED SECTION EXTENDING IN A TRANSVERSE DIRECTION; A PLURALITY OF SOLDER POCKET TERMINALS, SAID POCKET TERMINALS HAVING AN ATTACHING PORTION AND A POCKET PORTION, SAID EXTERNAL LEADS HAVING ENDS THEREOF DISPOSED IN AN AXIAL DIRECTION IN THE POCKET PORTIONS OF SAID POCKET TERMINALS AND SOLDERED THEREWITH, SAID ATTACHING PORTION BEING FASTENED TO ONE SIDE OF SAID FIRST INSULATING LAYER ON SAID SECOND ELONGATED SECTION THEREOF AND SAID POCKET PORTION FOLDED OVER ON THE OTHER SIDE OF SAID FIRS INSULATING LAYER SO AS TO OVERLIE SAID ATTACHING PORTION; AND MEANS JOINING THE SUPERIMPOSED INSULATING LAYERS DEFINING SAID FIST ELONGATED SECTION AND SAID TERMINAL PAD IN A FIXED ASSEMBLED RELATION WITH SAID COIL BODY, SAID ATTACHING PORTION BEING SANDWICHED BETWEEN SAID FIRST AND SECOND INSULATING LAYERS AND SAID FIRST INSULATING LAYER BEING INTERPOSED BETWEEN SAID ATTACHING PORTION AND SAID OUTER LAYER OF THE COIL BODY.

Images