US3496504A

US3496504A - Terminal assembly for encapsulated electric coil

Info

Publication number: US3496504A
Application number: US659217A
Authority: US
Inventors: Thomas J Daley
Original assignee: THOMAS J DALEY
Current assignee: THOMAS J DALEY
Priority date: 1967-08-08
Filing date: 1967-08-08
Publication date: 1970-02-17
Anticipated expiration: 1987-02-17

Description

T. J. DALEY Feb. 17, 1970 TERMINAL ASSEMBLY FOR ENCAPSULATED ELECTRIC COIL Filed Aug. 8, 1967 FIG. 2.

FIG. I.

FIG. 5.

INVENTOR Thomas J. Daley ATTORNEY United States Patent US. Cl. 336-96 7 Claims ABSTRACT OF THE DISCLOSURE An integral terminal assembly is formed of sheet metal and has two solderless terminals separated by a flat seal section. A first one of the terminals is connected to one end of a coil which is wound on a spool. This terminal is inserted in a pocket formed in the spool. Encapsulating material is formed around the coil, the spool, the first one of the terminals and a portion of the seal section. The remaining terminal is left free for subsequent access. The spool may be configured to admit encapsulating material between the spool and the coil.

Cross-reference to related application Reference is made to applicants copending patent application Ser. No. 659,216 filed concurrently herewith and directed to an encapsulating process and product whichare herein disclosed.

Background of the invention This invention relates to a terminal assembly and has particular relation to a solderless terminal assembly for an encapsulated coil.

Electrical connections to an encapsulated coil having a winding of small gauge wire may be made to the ends of the winding if they are permitted to project through the encapsulation. In alternate constructions each end of the winding may be provided with a terminal which is ac cessible exteriorly of the encapsulation.

Summary of the invention In accordance with the invention, each end of the coil winding is provided with a double terminal assembly. This assembly includes a first terminal preferably of the solderless type which is connected to an end of the winding and which is encapsulated with the winding. A second terminal preferably of the solderless type is connected to the first terminal through a seal plate and is located exteriorly of the encapsulation to permit subsequent connection thereto of a lead wire.

It is therefore an object of the invention to provide a double terminal assembly for an encapsulated coil.

It is a further object of the invention to provide a double terminal assembly for an encapsulated coil which includes a first terminal located within the encapsulation and connected to an end of the coil and a second terminal located exteriorly of the encapsulation.

It is another object of the invention to provide an improved process for constructing a terminal assembly for an encapsulated coil. 1

Brief description of the drawings Other objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a view in elevation with parts broken away of an induction Watt-hour meter embodying the invention;

FIG. 2 is a view in elevation with parts broken away of the voltage coil employed in the meter of FIG. 1 associated with encapsulating apparatus;

3,496,504 Patented Feb. 17, 1970 Description of the preferred embodiment FIG. 1 represents an induction watt-hour meter having an electromagnet 1 which provides an air gap for an electroconductive disc or armature 3. The electromagnet 1 includes a magnetic structure generally formed of laminations of soft magnetic steel and providing a voltage pole 5 and current poles 7. A voltage winding 9 surrounds the voltage pole and current windings '11 are associated with the current poles 7. Structures of this general type are described in the Electrical Metermens Handbook, 7th edition, published in 1965 by the Edison Electric Institute of New York City. As pointed out in this handbook, pages 673 and 674, the meter stator may have a 10 kilovolt impulse withstand level.

The voltage coil 9 has a large number of turns of small diameter electroconductive wire which is of the insulated or enameled type. As an example a voltage coil designed for energization from a 240 volt alternating current circuit may have 5500' turns of No. 33 wire (American Wire Gage).

The voltage coil 9 is of the random wound type wherein the turns are wound on a spool or bobbin having a central support 13 and a pair of

flanges

14 and 15. The central support 13 is in the form of a tubular sleeve which may be of circular cross-section but more commonly has a rectangular cross section adapted to receive snugly a voltage pole 5 of rectangular cross-section.

If the turns are wound on a conventional spool with the end turns in direct engagement with the flanges of the spool it will be found diflicult to obtain the desired level of resistance to voltage breakdown. One of the principal breakdown points in a random wound coil of conventional construction is between the start and finish layers or intermediate layers at the interspace of the enameled wire and the spool flange. If such a coil is encapsulated the forces generated during the encapsulation tend to reduce the start to finish distance and this reduction decreases the breakdown level.

Preferablythe end turns of the coil are spaced from the flanges by a layer of insulating material which is molded into intimate contact with the end turns. To this end the flanges may be provided with a large number of ribs 17 as shown in FIG. 3. These ribs space the end turns of the coil sufficiently from substantial portions of the flanges to permit the introduction of hardenable insulating material in liquid form into the spaces established by the ribs. The material may be a solid at room or ambient temperature which becomes liquid under the temperature and pressure conditions present during such introduction.

After the winding is applied to the spool the resultant structure is placed in a mold 19 having a cavity corresponding to the desired resultant outline of the coil. The mold includes a top 19A, a bottom 19B and a core 20 for the central support to prevent entry of encapsulating material into the central support. The mold also has an inlet 21 through which suitable encapsulating material may be introduced by a transfer ram 22. The encapsulating material is applied in liquid form through conventional runners and gates and is designed to harden in place to provide good insulation for the winding. Conveniently the encapsulant may be solid under ambient temperature conditions encountered by the meter during use, but may be liquid under the temperature and pressure conditions employed for encapsulation. Nylon and a thermosetting polyester resin are examples of suitable, encapsulating materials. Preferably the encapsulating material is an epoxy resin provided with a filler such as fiberglass.

When the encapsulating material is applied in liquid form to the mold it flows between the ribs 17 on the flanges into direct engagement with substantial portions of the end turns of the winding. v

In a preferred embodiment the encapsulating material is forced into the mold under substantial pressure such as 2000 lbs. per square inch. Such pressure tends to compact the windings of the coil and to force the end turns .away from the associated flanges. This has the effect of intro ducing a continuous layer of insulating material in direct contact or engagement with the end turns and located between the end turns and the associated flanges. The encapsulating material is now permitted to harden and if the material is of the thermosetting type heat may be applied to expedite such hardening. I J

The introduction of the encapsulating material into direct engagement with the end turns has made it possible to increase the breakdown voltage of the random wound coil to more than 225% of the values previously obtained, and increases of more than 300% have been obtained. For example 240 volt watt-hour meter voltage coils have been constructed with a breakdown voltage of the order of 23 kilovolts.

The elimination of air spaces resulting from the intimate contact of the encapsulant with the wire turns provides the additional benefit of reducing the harmful effects of corona. This elimination may be further assisted by utilizing the well-known vacuum molding techniques during encapsulation.

It will be noted that the encapsulating material together with the spool forms a complete encapsulation for the voltage coil. If desired the encapsulating material may be introduced between the turns and the central support 13 to increase the insulation between the turns and the voltage pole which is located within the central support. To this end ribs 17a on the outer surface of the central support may be provided to space adjacent coil turns from substantial portions of the support.

When the encapsulating material is applied it flows into the spaces between the ribs 17:: of the central support and compacts the coil to form a substantial layer of insulation between the coil and the central support. For many applications these additional ribs 17a are not required.

In the modification shown in FIG. 4 the ribs on the flanges are replaced by holes 23. Thus in FIG. 4 the flange 15 of FIG. 3 is replaced by a flange 15a of sheet insulating material having holes 23 which extend through the flange in a direction parallel to the axis of the central support to expose substantial portions of the coil end turns to the exterior of the spool. When the spool of FIG. 4 and the random wound winding thereon are encapsulated in the manner discussed above the liquid encapsulating material flows through the holes 23 into contact with the end turns. When the encapsulating material is subject to pressure, the windings are compacted and a substantially continuous layer of insulating material is molded into intimate engagement with the adjacent end turns.

In accordance with the invention electrical connections to the coil are made through a double-terminal arrangement. In a preferred embodiment the flange 14 is proleaving the solderless connector 31 free to receive an ex-' ternal lead. The mold is offmulti-part construction and provides parting surfaces engaging the plate 29. Thus the plate 29 providessealingsurfaces engaging the adjacent parts of the mold. A similar terminal construction 27a, 29a, 31a is shown for the other end of the coil.

In order to hold the terminal assemblies during the molding operation, the flange 14 has two pockets 35 and 35a proportioned to receive the connectors '27 and 27a respectively.

The complete spool may be constructed in any suitable manner. Preferably the spool including, the central support 13, the

flanges

14, 15, the ribs 17, the pockets 35, 35a, and thelslot are molded from a suitable insulating material which may be similar to that employed for ,encapsulation provided that it is capable of retaining its shape during the conditionsof encapsulation.

The terminal assembly is constructed from a sheet of electroconductive material preferably copper-containing, such as a sheet of brasshaving a thickness of 0.020 inch. From this sheet iscut or punched a blank having the configuration shown inFIG. S. This blank has a rectangular central portion providing a. seal plate.29.,Two fingers 41 and 43 are attached to one end of the plate 29 through a neck 45 which is narrower than the adjacent dimension of the plate 29. The fingers 41 and 43 subsequently are bent or crimped into engagement with one end of the coil as shown inFIG. 6. This construction provides a solderless terminal 27 in a manner Well understood in the art.

In a similar manner two fingers .47 and 49 are attached to a second end of the plate 29 through a neck 51. An additional pair of

fingers

53 and 55 are connected to the

fingers

47 and 49 through a neck 57. These two pairs of fingers are bent into U configurations to constitute the secondsolderless terminal 31". When the end of an insulatedconductor or lead W is partly stripped and laid in the channels formed by the U-shaped configurations the

fingers

47 and 49 may be crimped into engagement with the striped portion of the lead and the

fingers

53 and 55 may be crimped into engagement with the insulated portion of'the lead. A solderless terminal of this type is well known in the art.

wire.

vided with a slot 25 through which the inner end of the As previously pointed out the terminal 27 and the portion of the plate 29 is located within the encaspsulation of the'coil as shown in FIG. 2. Portions of the plate 2 9'are engaged by parting surface of the mold to form a seal for the encapsulating material.

What is claimed is:

1. A terminal assembly comprising a single sheet of electroconductive material having a seal section, a first solderless terminal integrally projecting from a" first side of said seal section,- and a second solderless terminal projecting integrally from a second side of said seal section, each of said terminals including a pairof crimping fingers, whereby each of said pairs of fingers may be crimped upon a wire placed therebetween in combination with a coil assembly having a winding of electrically-conductive wire, and an encapsulation of insulating materialfor said winding, said first solderless terminal'being' connected to one end of said winding and being located within said encapsulation, and 'said second solderless terminal being located'outside said encapsulation for reception of a lead 2. A coil assembly as claimed in claim -1 wherein said seal section is essentially a fiat plate located intermediate said two terminals, said terminals being aligned with each other.--- 7 T 3. A coil assembly as claimed in claim 1 wherein said terminal assembly is constructed of sheet metal," said first solderless terminal extending away from the seal section in a first direction and having a width adjacent the seal section which is'less than the adjacent width of the seal section, said first solderless terminal having first and second pairs of fingers spaced successivel from the seal section, the first pair forming a U-shaped channel for receiving a wire portion, and the second pair forming a U-shaped channel for receiving a Wire portion covered with insulation, said fingers being crimpable to establish contact with an to support an insulated wire, said second solderless terminal extending away from the seal section in a direction opposite to the first direction, and having a Width adjacent the seal section which is less than the adjacent width of the seal section, said second solderless terminal having a pair of fingers forming a U-shaped channel, said last-named fingers being crimped to engage and hold an end of the Winding Wire introduced from the seal-section of said last-named channel, said seal section comprising a flat plate partly within and'sealed to said encapsulation.

4. The method of constructing a coil assembly which comprises cutting from a single piece of electroconductive sheet a central seal section, a first terminal section extending from a first side of the seal section with a first pair of fingers and a second terminal section extending from a second side of the seal section with a second pair of fingers, winding wire to for an electric coil, guiding one end of the coil Wire adjacent the first terminal section, bending the first pair of fingers to contact and hold said wire end, and forming insulating encapsulating material around said coil, said first terminal section and said wire end to leave said second terminal section exposed for subsequent access.

5. The method of claim 4 wherein said guiding comprises guiding a terminal portion of the coil wire from the winding towards a point adjacent the seal section and thence to a Wire end spaced from the seal section in the direction of the first terminal section, and bending the second pair of fingers to form a U-shaped channel aligned With the first terminal section.

6. The method of claim 4 wherein said wire is wound on a spool having a pocket formed therein, and wherein said first terminal section is inserted into said pocket prior to said step of forming insulating encapsulating material.

7. A coil assembly as claimed in claim 1 wherein said coil assembly comprises a spool having a pocket therein, said winding being Wound on said spool, said first solderless terminal being inserted in said pocket.

References Cited UNITED STATES PATENTS 731,400 6/1903 Worthington 339-223 2,471,869 5/1949 Gebel 339-223 XR 2,718,627 9/1955 Swenson 339-276 2,802,193 8/1957 Biba et al. 336-192 XR 2,962,678 11/1960 Gellent et al. 336-192 XR 3,043,994 7/1962 Andeison et a1. 336-96 XR 3,051,773 8/1962 Batcheller 339-276 XR 3,209,311 9/1965 Kukla.

THOMAS J. KOZMA, Primary Examiner US, Cl. X.R. 29-605; 336-190, 192, 205; 339-223 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,496,504 February 17, 1970 Thomas J. Daley It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification, line 4, Thomas J. Daley, Rte. 5, Raleigh, N. C. 27604" should read Thomas J. Daley, Raleigh, N. C., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa. a corporation of Pennsylvania (SEAL) Attest:

WILLIAM E. SCHUYLER; JR.

Commissioner of Patents Edward M. Fletcher, Ir.

Attesting Officer