US2533717A - Method of making electrical condensers - Google Patents

Description

Dec. 12, 1950 P. R. couRsEY 2,533,717

METHOD OF MAKING ELECTRICAL CONDENSERS Original Filed Feb. 28, 1947 2 Sheets-Sheet 1 ATTORNEY Dec. 12, 1950 P. R. COURSEY 2,533,717

METHOD OF MAKING ELECTRICAL CONDENSERS Original Filed Feb. 28, 1947 2 Sheets-Sheet 2 0/ T'LETE.

INVENTOR BY 69/44 fifirzazwsev #n flag.

ATTORNEY Patented Dec. 12, 1950 METHOD OF MAKING ELECTRICAL CONDENSERS Philip Ray Coursey, Kingston, England, assignor to Engineering Development Laboratories, Inc., New York, N. Y., a corporation of NewYork Original application February 28, 1947, Serial No. 7

1948, Serial No. 26,997

8 Claims. (01. 24255) This application is a division of Serial #731,507, filed February 28, 1947.

This invention relates to electrical condensers of the kind in which the electrodes and insulating spacers are constituted by interleaved flexible elements of sheet material spirally Wound about a central axis, so that the convolutions of the electrode elements, such for example as metal foil, are separated by the convolutions of the flexible spacer elements, such for exampe as paper or other fibrous or porous material, the rolled unit being usually treated with a suitable impregnant.

According to the specification of the United States of America patent application Serial No. 718,634, dated December 27, 1946, the flexible elements are wound on a single central core held in tension While being rotated about th longitudinal axis of the core which is preferably constituted by a wire driven at both ends simultaneously. It has, hitherto, been found desirable for some purposes to enclose a small condenser of the rolled type within a casing of mouldable material, such for example as Bakelite. The condenser is usually wound, impregnated and the terminal leads attached, this unit being finally enclosed, by means of a moulding press, within the said casing. With this method, however, it is difficult to obtain moisture-proof seals where the terminal leads leave the casing, so that moisture may find access to the rolled condenser within the casing. Moreover, the heat applied during the moulding operation is liable to affect the insulation and electrical qualities of the condenser unit, and one object of the present invention is to overcome these difiiculties. A further object of the invention is to provide improvements in or modifications of the core upon which the interleaved flexible elements are spirally wound. These and further objects will become apparent from the appended claims and the following description of the accompanying drawings, in which Figure 1 is a diagrammatic representation, in side elevation, of apparatus for spirally winding the interleaved flexible elements,

Figure 2 illustrates in vertical section on the line 22 of Figure 1, the chucks and winding gear only,

Figures 3 to 6 show on an enlarged scale the steps involved in anchoring the ends of the flexible strips relatively to the core,

Figure 7 shows the rolled unit in side eleva- ,tion,

Divided and this application May 14,

ure 7 arranged within a ceramic tube shown in longitudinal section,

Figures 9 and 10 are views similar to Figure 8 but of modified arrangements.

As shown in Figures 1 and 2, two plastic monofilm or similar threads A having an overall di. ameter of approximately 0.0012 to 0.0015 of an inch are threaded through the axial bores in two aligned rotary chucks B respectively, carried between supports A1 mounted on a base A2, one or each of the chucks having an axial micrometer adjustment B1 (Figure 2) whereby the threads A can be subjected to a required degree of mechanical tension after the core A has been gripped in the chucks B by tightening the heads B2. -The two chucks B are driven, in synchronism, through a handle B3 and tooth gearing B4, so that the drive is applied to both ends of the core A simultaneously. Carried by members C, D on the base A2 with their axes parallel to the axis of rotation of the core A are a plurality of supply rolls two of which C1, C2 are constituted by strips of metal foil whilst the two others D1, D2 are constituted by strips of paper which are to constitute the insulating spacers between the foils or electrodes. The foils C1, C2 have a thickness of, say, not more than five microns (0.0002 inch approximately)- whilst the spacers D1, D2 may have a thickness of up to 12 microns (0.0005 inch approximately) if used singly or up to 6.5 to 7.0.microns (0.00025 to 0.0003 inch approximately) if used in pairs. Where single paper spacers are used it is sometimes found advantageous to coat one or both sides of them, but preferably one side only, with a layer of lacquer or varnish for the purpose of filling up the irregularities in the paper surface which is adjacent to a metal electrode and so to reduce the liabilities to breakdown through this portion of the tissue.

As shown in Figure 3, the free end of the paper strip D1 is inserted between the insulating threads A of the core extending between the chucks B so that when the core is rotated by means of the handle B: the paper strip D1 will be wound on the core which then acts as a mandreluntil the strip D1 laps the core as shown. The endof the foil C1 is taken over two guide rollers E; interconnected by an inclined ramp E and thence to the angle formed betweenthe core A and the first paper strip D1 tangential thereto. The ban: dle B3 is now turned slightly so that the end of the foil C1 is wound in, whereupon the end of the second paper strip D2 is laid .over the foil Cl and thence to the angle between the" which is that of 3 strip C1 and the first convolution of the strip D1, as shown in Figure 4. Having again turned the handle B3 through a small angle to wind in the end of the paper strip Dz, the end of the second foil C2 is laid over a guide roller'Di and inserted into the angle between the second paper strip D2 and the adjacent convolution of the first paper strip D1. The handle B3 is now turned until the several foils and paper strips are wound as shown in Figure 6, the foils C1 and C2- and the second paper strip D2 being cut so that the strip Dz extends beyond the ends of the foils. The winding is now completed until the first paper strip D1 laps the roll whereupon the paper strip D1 is severed and has its. end secured byadhesive as shown at C3 (Figure 7).

The foils are so wound relatively to the paper spacers that whilst one edge C4 of the foil C1 lies wholy within the confines of the paper strips D1, D2 the other edge C5 of the foil C1 projects beyond the confines of the said paper strips. Similarly one edge C6 of the foil C2 lies wholly within the confines of the paper strips D1, D2 whilst the other edge C7 of the foil C2 pro ects beyond the paper strips. Thus the two metal foils C1, C2 have their marginal edges C5, C7 projecting so as to con stitute terminal connections for the purpose described below. It will be understood that the distancesbetween the ends of the paper conv'ol'u tions andthe adjacent edges C4, C6 of the foils are considerably exaggerated for the sake of clarity of illustration, only narrow margins being actually required in practice. Having cut oil the two projecting ends of the core A, the rolled unit shown in Figure 7 is inserted in a ceramic tube G (Figure 8) having internal metallized areas G1 so that when terminal leads F, F1 are soldered to the opposite terminal connections C5, C1,. these are simultaneously soldered to the metallized areas" G1. These soldered connections are such that they provide moisture-proof seals at the ends of the ceramic tube G whose contents, that is to say the rolled condenser elements, are thus sealed against the entry of moisture.

It will be understood that though in the arrangements above described the core is constituted by two insulating threads, the core may be constituted by a single insulating thread, such for example as a synthetic resin, the first flexible element being then merely attached to the core bv adhesive. Moreover, since the core is of insulating material and is not employed as one of the condenser terminals, either one of the flexible spacer elements, or one of the foils, may be connected to the core for initiating the winding operation.

I The rolled unit shown in Figures 7 and 8 may be treated with an impregnant of mineral wax, oil, jelly or the like, or with an impregnant of high dielectric constant, such for example as one of the chlorinated naphthal'enes or chlorinated diphenyls, or a wax-like hydrogenated or bydroxylated castor oil, impregnation being effected before the terminal leads F, F1 are soldered to the terminal connections so as to seal the convolutions of the rolled unit.

When two or more threads are included in the reference to Figure '7 except that the interleaved flexible foils and .paper strips are wound on a single core A3 of insulating material, the first paper strip D1 being secured to the core A3 by means' of adhesive whereupon the unit is wound as-described'wi'th reference to Figures 3 to 6 above. Having severed the two ends of the core A3 level with the projecting ends C5, C7 of the foils C1, C2, two terminal end plates F2, F3 soldered (or otherwiseattached e. g. by riveting or welding) to terminal leads F4, F5 are themselves soldered to the projecting terminal connections C5, C7 and to the metallized areas G1 within the ceramic tube G, so as to form moisture-proof joints therewith, thus. again sealing the rolled unit within the tube G. The sealed unit thus formed is now moulded ina housing of mouldable insulating material H, for example of Bakelite with the terminal leads F4, F5 extending from opposite ends of this insulating housing.

In the modification. shown in Figure 10 the ends of the ceramic tube G are closed by metallize'd ceramic plugs J, J1 which are soldered. to the metallized ends G1 of the ceramic tube G, the terminal leads K, K1 extending from the terminal connections C7, C5 through apertures in the plugs J, J1 with the leads K, K1 soldered to the plugs J; J1 around said apertures, the terminal leads K, K1 being soldered to the connections C7, C5 through metal discs K2,. K3. lhough this condenser maybe employed without a surrounding insulating housing, Figure 1.0 shows the sealed unit mou ded within a casing H1, for example of Bakelite or' other mouldable material.

It will be apparent that instead of the tube G being of ceramic material, it may be of metal into which the ceramic plugs J, J1 are soldered. Alternatively, whether the tube G is of ceramic material or of metal, only one ceramic plug may be used, the other terminal being connected to the metal tube by insertion of a solid disc of metal to close one end of it.

The unit rolled upon an insulating core may, if desired, be disposed and sealed within a metal sleeve or thimble, the sealing being efiected by an insulating washer or bush such for example as a, ceramic plug through which the terminal lead extends. The sealed unit may then be moulded within a casing of mouldable insulating material, such for example as Bakelite.

While there has been shown and described in the foregoing a preferred embodiment of the invent on, it will be understood that various modifications and changes in the construction and methods shown and described herein as well as the substitution of equivalent constructions and steps for those disclosed may be made in accordance with the broad scope and spirit of the invention. The specification and drawings are accordingly to be recorded in an illustrative rather than a limiting sense.

I claim:

l. The method of manufacturing an electrical condenser, according to which a plurality of interleaved flexible conducting and insulating elements are wound spirally upon a rotating core comprising at least one thread of insulating material, while applying mechanical tension to said core during the winding operation.

.2. The method of manufacturing an electrical condenser according to which a plurality of interleaved flexible conducting and insulating elements are wound spirally upon a rotating core comprising at least one thread of insulating material, while applying mechanical tension to said core during the winding operation, the drive being applied to the core at both ends thereof simultaneously.

3. The method of manufacturin an electrical condenser according to which a plurality of interleaved flexible conducting and insulating elements are wound spirally upon a rotating core comprising a plurality of threads of insulating material, while applying mechanical tension to said core during the Winding operation.

4. The method of manufacturing an electrical condenser comprising flexible conducting and insulating elements spirally wound about a com mon axis, according to which a first flexible element is connected to a core held under mechanical tension and comprising at least one thread of insulating material, rotating the core so as to Wind said insulating element spirally thereon, and drawing successive flexible elements in between the rotating core and the part of the first flexible element tangential thereto.

5. The method of manufacturing an electrical condenser comprising flexible conducting and insulating elements spirally wound about a common axis, according to which a first flexible element is inserted between the threads of a core comprising a plurality of threads of insulating material, applying mechanical tension to the core while rotating it so as to wind said flexible element spirally thereon, and drawing successive flexible elements in between the rotating core and the part of the first flexible element tangential thereto.

6. The method of manufacturing electrical condensers of the rolled type comprising spirally winding flexible and insulating layers upon a rotating core consisting of at least one thread of insulating material, and applying mechanical tension to said core during the winding operation.

7. The method of manufacturing electrical condensers of the rolled type comprising spirally winding flexible conducting and insulating layers upon a core consisting of at least one thread of insulating material and being rctatively driven at both. ends simultaneously, and applying tension to said core during the Winding operation.

8. The method of manufacturing electrical F condensers of the rolled type comprising inserting a flexible condenser element between the elements of a core consisting of a plurality of juxtaposed threads of insulating material, applying mechanical tension to said core, and rotating said core while under tension, for winding thereon alternate conducting and insulating layers, to produce a rolled condenser unit.

PHILIP RAY COURSEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 728,780 Spitdorf May 19, 1903 1,744,616 Cunningham Jan. 21, 1930 1,960,944 Knudsen May 29, 1934

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