US1706816A - To xwrireless s - Google Patents

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US1706816A
US1706816A US1706816DA US1706816A US 1706816 A US1706816 A US 1706816A US 1706816D A US1706816D A US 1706816DA US 1706816 A US1706816 A US 1706816A
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sheets
stack
condenser
casing
paraffin
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G13/00—Apparatus specially adapted for manufacturing capacitors; Processes specially adapted for manufacturing capacitors not provided for in groups H01G4/00 - H01G11/00

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  • the :foils adapt-ed for. gmy, pr oeesses are-preferably SQf.l3 fiIld.IlQl1- j resilient so that;.asthe nesult ot the execue .ti n .ot e.prec ssjth yrare l t me 901111 .tact with themicasheets; their surfaces ill-j. id estaeketshe b ng e f number of... the selections got.
  • the invention consists injc'ertain of the stepsof the processes described herein and ,in certain .combintion's of ⁇ such-steps, in the [improved condenser itselLT-and in certain features of apparatus mp1oyed, ,au s' will Figl (i is. an: elevation showy g ⁇ lthe' coins .pr e'ssio n of the material-stackin the pressafter removal from the bath .of
  • Fig. .7 is ,elevationof part of u etmaterial-stack .which .has been. selected there from. for use in or as a. condens eij staclc Fig' 8 s an'; e1 ev,auoa or assem led condenser stac'k fmf condenser consisting. of a or'E eiicjaia n' mba-baaga em anthe end b ea aw- Qwing. ,to the;soft inertpor.
  • Fig. 11 isla detail offlthe leafv spring forming apart of the press oi Fig.9. l
  • Figfli is an elevation showings form of permanent spring clamp ,for the condenser.
  • F ig.. 13 diagrammatic planoflappm ratus involving a vacuuin tank in. which is inserted-the apparatus of Fig. 9. and "a wax -reservoir or paraffin tank connected by pipes to the vacuum tank for the purpose of filling thecondenser easing with embedding, paraflin.
  • Fig. 14 is an elevation of appa-rtaus employed in the special process of cooling the embedding .parafi in in the'condens r casing.
  • Fig. 15 is an elevation, partly in section, of the condenser casing of Fig. l.0.containing the einbeclment and condenserpwith casing coi er in place.
  • sscs hereof is preterably ie-watery iirmn moisture-as by'heatingitto froin 100 centit rdde'toism "C. M
  • the condenset'stnatle by 'tlie pi'ocesse ereare "n'i'oi'e' 'ii-rtichlarly atlaptetl fbi use "iintlc'ncdntliti 'it is fiflrptiititht that there shall be miniih'urti el'e'ctiicallb'sses in the condetise'r in ervice's: itii'atliotelegraph 'tthhitiitt'ers 61 iii "powct lines, laboratory standards antl theli'ke Tlieeontleii'ser seek, in any case, may be employed as a unit in any "desired way,6
  • Inkpre'pai'atiiihforthejprocesses the sheets of'niica and toihare' 'cut to whatei-er sizes Iii'ayhe desired rm a particular design of coudehser, 'i'hdfoil sheets beiiiig usually longer and harrowerthan the mica sheets as in the culinary sheet condenser.
  • the toil sheets are wlled to be perfectly flat, and the mica. sneets are tested, dried. and stored ih'air-tiigiht coutainers to await execution ofthe processes-1.
  • thest'ac'k i's'called 'the material-stack because it constitutes the material out of which the dvtittia'l condenser 's'tac'k (or simply condenser) is tob'e' made as by sele'ct'ing'a sufiicieht "length 'or Inegths of the 'iuateriahstack 'ithichh'as or liave electrical capacity suitable for the condenser.
  • Figs. 2 and. 3 show the building stand of Fi 1' inserted in a waxing tray'5, the latter bciiifi heated by a. very mall lhinseh burner -6 (Fig.3) tofkeep simpl warm the paraflin intlie tray.
  • Ilhstbetore each sheet of In'icaor foil is'plac'ed first on top of thebase 1 and then on top of oneanother alternately, the operator dips eachsu'ch sheet inthe paraffin in tray '5- and then places it onthe growing stack shown'in Figs? and 3. 'As stated, the
  • each coated niiba sheet ispla'ced a co'ated foil sheet as8,'the tirst foilsheetb'eing'placed say so thatits leftfiroj'ectsto the left (it the mica sh'et 7, but at its right it does not extend to 'tl'ieedgc Git-he inicasheet 'i.
  • another coated r'n'ica sheet- is placed exactly on topof the first foil sheet 7. heing alined therewith by the cut away portions 3 of the 'posts Then the 'ne'xt.
  • coated foil sheet as 9 is'placed on top of the lasti'nica. sheet llut extending to the right beyond the mica sheet and at its left not. extend ing to the left end of the mica sheet. As'the operator puts each foil sheet in place, she cana'iid should ol'rservc Whether any air bubble is entrained in the parailin (due possibly to incomplete dipping), and it there be, or preferably in ever ease,'she su'ioeths down (squeegees) each foil to squeeze out the air. Likewise, in pet-ting each dipped mica sheet in place, she prcsses it dawn on the coated foil sheet beneath it, for the same purpose of squeezingout air.
  • the material-stack is built up ofalternated sheets of mica and toil, while the si1cce's sive'f0il sheets are placed so as to'eritend respectively at opposite ends of the stack and overlap one another (although separated'by a mica sheet) in the central part (lift 1B'illfiSiOfltllG mica sheets in the stack.
  • "lhehott oin "1 of the building stand (Figs. 1 and 2)" is set down in the body of liquid paratfin in tray 5, so that it is heated by the parafkept warm, i.
  • Tli'e "material-stack may be bu1lt-completely undera bath-of l'pa'rafiin, but as described above it is usuallybuilt-in atmosphere with its lower end "in heat; conducting relationwith'the parafin intrayfi, which causes less exposure of the'ope'rators fingers to the heated Y paraflina lt' is i immaterial that the small corner's or edgesof the .sheets which are held in'gthe operators fingers during the dipping operation be not-coated with the paraffin, for the dipping and building operations'leave suflicicnt paraifin' on thefsheet's s0 that-inthe building operation itself and espe cially during the subsequent squeezing or washing out operation the entire surfaces of the sheets are washed of air and moisture hy the outgoing-paraflin, it not being the object of the invention to retain-any paraffin permanently on the sheets. 'Ihe'temperature of the parafiin in building tray 5 during
  • temporary section separators of metal or any other desired material may be inserted 'as a convenient method of separating the sections in the materialstack, particularly if during the building operation pains are taken to insure that each section has the same electrical capacity, as by using material of uniform thickness for the :mica sheets and byinserting the temporary ing at substantially separators or markers above the same number of mica sheets for each section.
  • Fig. 4 This frame consists of a substantial metal base 10 with four upright metal posts 11 at the four corners thereof. Each of the four posts 11 is provided with cut away portions 12 like the cut away portions 3 of the posts 2 of Fig. l, to aline the four corners of the mica sheets in the stack.
  • the next step consists in inserting the pressing frame containing the material stack into a bath of hot-molten paraffin in a temporary container 14 (Fig. 5). During this bath, the container is heated by the flame of an'ordinary Bunsen burner 15. In this step, the paraflin coatings on the sheets which yet remain as thin layers licti-x'a-en sheets in the material stack are completely liquefied. This heating bath is maintained for about twenty minutes, the temperature of the parafiin hol35 C. iiy the time the material-stack is thoroughly iwahwl, some of the moisture remaining with the parailin between the sheets inside the stack becomes vaporized and escapes from the stuck into the bath. Such moisture that which may have been entrapped in the coating parafiin during the dipping and building operation when the parafiin was not at so high a temperature as in this bath, i. e., being then preferably less than 100 C.
  • a cross piece 30, (Fig 10) having a central opening up through which projects the stud terminal 28. This serves to center the condenser 25 in its casing 26; and this temporary head 29 ser'ves'to receive the sesaf spring 37, as shown in Fig. l1.
  • afiin which is afterwards filled in around the condenser in its casing.
  • Theentire casing 26 is mounted in the press shown in Fig. 9, said press consisting of top and bottom plates 31 and. 32, held together by bars 33 and 34 threaded at their ends and provided with nuts which hold the frame together.
  • a screw 35 which extends down through a threaded hole in top plate 31, and'is provided with asuitable handle 36.
  • a This spring consists of two-leaves bolted together at their ends and drilled with the central holes 38 and 39 to receive respcctively'the clampscrew 35 and condenser terminal 28..
  • The. condenser stack 25 in its casing 26 with clamp applied as shown in Fig. 9, is now subjecti ed to aprocess of pre-heating preliminary to the embedding operation.
  • the temporary head 29 is open at its top save for the cross member 30 (Fig. 10), and has ,onlyside walls to constitute an.u.p-' ward extension of the side walls of -casing 26.
  • the process of pro-heating consists in pouring hot; wax throughsaid head down into the space in casing 26 around the condenser 25, until'both casing and head'are filled; and thereafter, and while this parafiin is in the casingandhead the heat of a Bunsen burner fiame'is applied to the bottom of the casing (similarlyto Fig. 5) for the purpose of cooperating in heating thoroughly the casing and condenser 25, this latter being done by playing the gas flame around the exterior of the casing.
  • This gas flame may be applied to the casing prior to the pouring in of the paratlin, but if that be done care should be taken that such application be not caress-ire on account of the-possibility of overheating and carbonizing the parafiin'sheath or marginal paratiin around the condenser, and of melting the soldered connections of the condenser sections, which should not be heated as high as 150 C.
  • the hot parafiin in the casing serves to thoroughly heat the condenser itself, thereby condenser is thoroughly heated and itsseud para'ffin liquefied, the hezitingbath ofparafiin 1S pourecl out oflt'he easing head 29, by an inuersion ofthe en reejgpa-rntus ofiFij 9
  • Fig, 12 isone ql ithesides oi; the assembly and ntwhich the series connections are made and from which. pnejeetthevzs pntar iilg in;
  • wire consists n-eterably of piano steel wire and is wound tightly arounclthis assembly, as shownin Fig-'12;
  • This heating bath is prel'irninziny to a further coin-j pression, but it also servesto drive out of'and' oil from the condenser any or moisture Whichmey ha ve been'introduced into. the marginal sincethe production ofthe condenser from theniaierial steek or since the air and moisture were first-previously washed out from the materiel-stack. Pf the eohl'compression j'ust preyi'ous to ,thlis heating bath be omitted. i. c. ifthe condenser be subjected-to the healing bath without, being under.
  • the Yzilne may be lost 01 the advantages of the originnlliot comprcssion of the material-stack, ii 0., the sub-, stnntiul washin out oi. 'fl.l1',.U)'ol moisture from between the sheets in the interior oflhe stzn-k.v
  • olfrthis heating bnlh, all the pornfii'n )fltl'clllililllllg in and about the eondenser (and ,ztt this stage there is.
  • the ermenent small-clamp 4'5 is turther thghtenei, to maintain the compression at. tained the large clamp or press, which at this stage should have been set for about one thousand pounds per square inch of active area of the overlapping portions of the foil sheets in the centre of the condenser.
  • Such increase of compression and the further tight ening of the permanent clamp are permitted when at this stage there is any paraiiin remaining inside the stack as between the sections, such paraffin being of course soft as the result of the heating bath.
  • the condenser is removed from the large clamp or press.
  • the top lead 40 (Fig. l5) may be connected to the condenser terminal 28 (Figs. 12 and 15), the latter being centered through ,the opening in the head 29 of Fig. 9, in order to center the condenser of Fig. 12 in the easing 26 of Fig. 9.
  • the vacuum treatment need not be applied to the stack for more than a -few minutes, because it does no good save while the stack is hot and its marginal wax is liquefied or soft, the obj ect of the vacuum treatment being to remove air and moisture from the liquid or softmarginal wax in preparation for the process next to be effected, of enveloping the stack in hot. paraffim for eventual cooling and embedment.
  • the maintenance of the vacuum around the stack until the latter is submerged in the parailin serves to prevent the entrapping of any air or gaseous vapor in any portions of the final embedding parallin, which may be so close to the condenser as to permit electrical losses or breakdowns in service due to such air or moisture.
  • the hot embedding parafiin is being flowed into the exhausted space around the con-- denser, the air or vapor which may have been in the marginal paratlin of the condenser and which has been removed therefrom by the vacuum and attenuated and distributed through the vacnous space in the tank is prevented by the continuation of the vacuum from being concentrated or entering again into the marginal wax.
  • tank 6 condenser is, desired these processes o f yapnnm and filling-in embedding .parefl n While under vacuum are extremely important.
  • An equalizer pipe-6 3 is connected between the wax reservoir 511411111 the tank 46. Its
  • anytillip fitter tlielilfiowingparaliin has s bmerged he C ndens n -its easing. the vacn ni treatment can be terminated by] e lo.
  • Valve fl-is opened inpipe (the end of which is open toithe atmosphere), in order to causeatmospheric pressure to force paraffi i reniaining'in pipes 419 against-therednced helcl i tie le t reservoir 51 above tank 46.1 llnis; the m a fin may flow by gravity 'f en ese -Y0i. f 51f to the condenser x,caminfgs 151,6, "i rtefl pr Ct-iv 0f the ai pr ssiu-eln the lett r? HID" *iplaee i new;
  • the air blast may be directed against the desired lower portions of casing 26 by means of flexible tubing 57.
  • the npper part of the liquid paratlin bodyfin casing 26 andhead29 may be and has beensuccessfiilly in practice, heated as by-peuringin additional hotpal-at fin f om.
  • Fig, 14 is represented in dottcdlines the condenser with all of the temporary clam ping apparatus of Fig. 9, including the leaf sp r ing 3'(j but whenthe permanent spring ela 1 np of -,Fig. 12is used,.such temporary apparatus willnot be used, and the appai atus subjected to the cooling treatment of Eig. 14 will consist simply of the condenser casing 26 containingcondenser 25 in ifs'spr'ing clamp 45 of Fig.12, and thetcmpora yhead 29, heatingcoil-58, and any of the described means for abstracting heat from thelowerlportion of the liquid paraffin in the condensercasing, and adding heat to the top.
  • the permanentcmbedding paraffin in the casing (as distinguished from the temporary paraffin in the temporary head 29) is made substantially solid. and voids otherwise tending to become fixed in the upper part of casing 26, in the neighborhood of the upper or high potential end of the condenser, are caused to be established, if anywhere, in the temporary paraffin in the temporary head 29.
  • head 29 in connection with the repeated addilion of hot mraffiu to compensate for the shrinkage during cooling, prevents the formation of a final depression in the paraffin in the top of casing 26, so that the final cooling of the top of the paraffin in the casing results in a uniform mass of paraffin free from any lines of cleavage which might exist in the parafiin in the casing if it were allowed to solidify with a depression in its top surface and if after solidification additional paraffin were added to fill up the depression.
  • the paraffin commences to silidify at the bottom of the casing andat lower portions along the sides of the casing and the sides of the stack resting on the bottom-of the casing 26, the rest of the paraffin in the casing26 and head29'remaining liquid.
  • the solidification extends h1gher.up from thebottom of the casing and still higher up inside the sides thereof and along the sides of the condenser, so that the remaining liquid paraffin is U-shaped in cross-section around the condenser.-
  • the liquefied r mainder at all times bears down u on and against .the upwardly moving sur aces of solidification and directly follows up the shrinkage or contraction at such surfaces accompanying the solidification, to the end of preventing voids or cracks.
  • the surfacesof solidification drive upwardly any remauent air or moisture, not only to the upper part-of the casing 26, but up into the head 29. If'the head 29 be sufficiently high to contain a sufficient volume of paraffin, then all the air and moisture as well as voids finally forming near the upper surface of the paraflin will be contained wholly within the head, so that when later the temporary wax in the head 29 is cut off, there will be left no voids, air holes or depressions in the upper part of the casing in the vicinity of the condenser.
  • this cooling operation involves specifically the ap lication of heat (as in the preferred form) to the paraffin in the head 29, such application of heat may be discontinued after assurance is obtained by observatirm that solidification has been COlllph-ted of all the paraffin within the casing 26. It is to be understood that this cooling operation is conducted under at least atmospheric pressure, so that the atmosphere has access to the top of the molten paraffin in head 29, in order to assist in the cooling process in respect of the prevention of voids in the paraffin in casing 26.
  • this air or gas pre sure o top f the molten paraffin body may be greatly increased above atmospheric pressure, this increased pressure being advan tageously as high as 1-50 pounds, which can be maintained until complete solidification has been eflected.
  • the effect of such increased pressure is to com press any voids or bubbles in the pa rafiin. thereby making their effect less deleterious.
  • the condenser in its filled casing may be left in ianlr- 16 of Fig. 13 for the execution of the cooling process, and con'lprcsscd air from asuitable pump may be introduced into the tank 46 hy'way'of valve 52.
  • the application of additional wasinto the head 29 during the cooling process may be effected by way of the pipes'49'irom the paraflin reservoir 51, in which case, of course, the paraffin in reservoir 5-1 shouldbe subjected to at least tl'iesa'megas pressure as-that of the tank 46 by way of val-ve-645, in-order to permit the inflow of paraflin intotank 46.
  • a construction may be provided whereby the application of a coyei to the top of the casing' will serve in any well lmown manner to compress the condenscriiithe cas ing.
  • a permanent small clamp as in Fig.' 12
  • any suitable cover '60 is applied to the top of the casing over the embedding parafiin.
  • the modified form of small permanent clamp in the casing which is shown in Fig. 15, comprises a' U shaped steel yoke 59 which elnbraces'the condenser.
  • the U cnd is insulatedfrom the condenser as by a: stack of mica sl1cets 62. Two of these clamps are disposedsymmetrically on the condenser. The two ends of each clan'ip are entered by adjusting screws 61 which pass up through a steel spring plate 43* (common to both clan'ips), whereby plate 43"? is flexed to apply the desired compression.
  • Mica stat-E662 is placed on top of insulating'plate' (3ft (as of balielit'e) which in turn rests onf metal plate 27 which transmits the pressure of Insulating the clamps 59 to the condenser. plate 66' insulates the lead from the top of the condenser)
  • the condenser terminal 28 is'soldered atits bottom to the upper end of strip lead 40.
  • the condenser terminals may be brought out through the casing "in any desirable or well-known manner-as (Fig. 15) the high potential terminal 28 through'an opening in insulating cover and one terminal (that of low potential) may be constituted" by the metal casing 26 itself. pursuant to the common practice.
  • the foil sheets' mayhave some de gree of resiliency with-out resulting inbreaking down the hermetical sealing by the marginal she'atli' parafiinfespecially if the stack in 'th'e earl ta'ge's of the process have a sufficient thickness ofn ai g'iual sheath to prevent expansion "of the stack' (laterally with respect to the stack), and this may be obtained if necessary by suitable dipping in the paraffin bath fort-he purpose ofohtaining such substantial thickness of the marginal paraffin.
  • ⁇ Vhenevcr compression or clamps are refcrred to herein, such compression is to be understood to he the highest mechanical compression which is practicable to be applied on the soft lead-foil sheets, and this in practice is about 1,000 pounds or more per square inch of the active area of'each mica sheet, i. 0., that part of the mica sheet which lies betwecn theovcrlapping 'foil sheets, this being a pressure which amounts to about 'a ton or more on the entire end surface of an ordinary condenser 3"lliig'h by 2 long by 1%" wide.
  • I claim l The method of making an electrical condenser stack of non-porous dielectric sheets and metal sheets which consists in first coating the active non-porous surfaces of the sheets, prior to stacking them together, with a dielectric detergent liquid; thereafter stacking the sheets; and thereafter employing the detergent layers between the sheets in the stack to Wash out air or mo sture from he tween the sheets, by squeezing the sheets together when the detergent layers are liquid, thereby forcing out said layers with any entrained air or moisture from between adjacent sheets and permitting the non-porous surfaces of adjacent pairs of sheets, so freed of air and moisture between them, to lie together in intimate surface contact with one another in the stack.
  • the method of making an electrical condenser stack of non-porous dielectric sheets and metal sheets which consists in cansing the non-porous surfaces of adjacent stack sheets to adhere together temporarily during the stacking operation. by first coating the active non-porous surfaces of individual sheets, prior to stacking them together, with a normally solid dielectric detergent in hot tut) moltei'i condition, and then stacking such sheets together before said coatings on the facing surfaces of pairs of adjacent sheets being stacked together have cooled and solidilied; and, subsequent to such stackin em ploying the detergentlayers to wash out air or moisture from betnveen the stack-sheets, by squeezing the stack-sheets together when the detergent layers are in heated liquid condition thereby forcing out said layers with any entrained air or moisture from between adjacent sheets and causing the non-porous surfaces of adjacentsheets, so freed of air and moisture between them, to be squeezed together in intimate surface contact with one anotherin the stack.
  • an electrical-condenser comprising, a stack of non-porous dielectric sheets and metal sheets enclosed in a casingwhich consists in first coating the active non-porous surfaces of sheets, prior to stacking them together,-with a normally soliddielectric deter ent in hot molten condition; thereafter stac ing the sheets, thereafter Washing out air or moisture from betweenthe non-porous stack sheets by squeezing them together when the detergent layers between them are in liquid condition thereby forcing out said detergent, with any entrained air or ltlt) moisture, from between adjacent sheets and causing the non-porous surfaces thereof, so freed of air and moisture between them to be squeezed into intimate surface contact with one another in the stack; said squeezed-out detergent forming in a thin dielectric sheath around the edges of the sheets and the sides of the stack; continuing said squeezing.
  • an electrical condenser comprising a stack of non-porous dielectric sheetsand metal sheets enclosed in a casing which consists in first coating the active nonporous surfaces of the sheets, prior to stacking them together, with a normally solid dielectric detergent in hot molten condition; thereafter stacking the sheets; thereafter washing out air or moisture from between the non-porous sheets of the stack by squeezing-the stack sheets together when the detergent layers between them are in liquid condition, thereby forcing out said layers and any entrained air or moisture from between adjacent sheets; continuing such squeezing until the squeezed-out detergent dielectric has cooled and solidified in a sheath around the edges of the sheets and sides of the stack having the ability to hold the sheets in their intimate surface contact caused by the squeezing out of the detergent, air and moisture; discontinuing the squeezing operation when said dielectric sheath has cooled and solidified to hold the sheets in their intimate surface contact; placing the stack in a casing proportioncd relative to the stack to provide
  • An electrical condenser comprising a stack of sheets of non-porous dielectric and metal sheets and a casing enclosing such stack and proportioned thereto to provide a space between the sides of the stack and the casing, said space being filled partially with a sheath of normally solid dielectric material around the stack, leaving their surfaces in intimate contact with one another; and said space being further filled with a comparatively thick mass ofnormally Solid dielectric material; said two masses of dielectric material being solidified together and constitutingv a permanent embedment of the stack in the casing; and means holding the stack under high mechanical compression in the casing, thereby maintaining the intimate surface. contact of the stack-sheets during the solidification ofthe entire mass of dielectric in the space between the stack and easing.
  • an electrical condenser comprising a stack of non-porous dielectric sheets and metal sheets enclosed in a casing proportioned to provide a space between stack and casing, which consists in first coating the active non-porous surfaces of the sheets, prior to stacking them together, with a. dielectric detergent liquid; thereafter stacking the sheets, forming layers of detergent between the sheets; thereafter sqncezing out the detergent layers, when in liquid condition, together with any entrained air or moisture, from between the sheets.
  • the method of producing mica and foil sheet condensers having clean active surfaces of the sheets, and keeping the same clean which consists in building a stack of such sheets each first coated with molten parafiin before stacking, and keeping the growing stack warm and the coatings therebysoft during the stacking operation; subjecting such stack, with liquid paraffin layers between the sheets, to high mechanical compression, thereby squeezing out said layers with any entrained air or moisture and causing the sheets to lie in intimate surface contact with one another; placing such stack into a permanent casing and under high mechanical compression therein, with the edges of the stack sheets spaced from the casing; and filling such space with hot molten )araflin.

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  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Drying Of Solid Materials (AREA)

Description

March 26, 1929. G. w. PICKARD ELECTRICAL CONDENSER AND PROCESS Original Filed May 12 1920 6 Sheets-Sheet 1 I avwemkoz merPic/baml 81 flfglttowm March 26, 1929. G. w. PICKARD ELECTRICAL CONDENSER AND PROCESS Original Filed May 12. 1920 6 Sheets-Sheet 2 3140c 'wfoz Gre enlmf WkiltierHc/Eard @513 GHQ: 11c 1 March 26, 1929. 6. w. PICKARD 1,706,816
ELECTRICAL CONDENSER AND PROCESS Original Filed May 12. 1920 6 Sheets-Sheet 3 Gitenleqf Wfiiiiz'er Retard March 26, 1929. G. w. PICKARD ELECTRICAL CONDENSER AND PROCESS Original Filed May 12 1920 6 Sheets-Sheet 4 WWW W1 March 1929' G. w. PICKARD ELECTRICAL CONDENSER AND PROCESS Original Filed May 12. 1920 6 Sheets-Sheet 5 saux mu gave "for March 26, 1929. G. w. PICKARD ELECTRICAL CONDENSER AND PROCESS Original Filed May 12. 1920 6 Sheets-Sheet 6 Patented Mar. 26, 1929.
arren srarss.
GREENLEAF \VBSITTIER PiCKARD,"OF NEWTON CENTER, MASSACHUSETTS}'ASSIGNOR 'TO WIRELESS SPECIALTY APP'AEA us CORPOR TION E, NEW YORK.
COMPANY, 0E BOSTON, MASSACHUSETTS, A
' EL CTRICAL CONDENSER AND PROCESS.
A ucauonmeama 12, 1920, Serial is. $86,919. Renewed February '26, 1927.
- This inventionrela tes.to improvements in processes. and apparatus for manufacture of electrical condensers of thesheet type and f more particularlyofthe type wherein mica is used for the dielectriesheets. .-;;The' object of theinvention is to obtain ran improved condenser ofjthe -she et;type, which-comprises a stack-consisting as nearly ,aspossible}; of {only -;alternately-disposed sheets of mica;-andfmetal foil in permanently intimatecontaet with each other, the -inte rior of the stack betWjeenthe sheetsbeing freed as nearly as possible of air, moisturev the latter. being ,heated; i
and all materialscther than. the mica and foil sheets. tl1emselves, .themica. andg. .foil sheets hav ng .noth1 1 1g whatsoever;between.
them when th;e; .obj.cct of. the invention: is
coinpletely-.- attained. The :foils adapt-ed for. gmy, pr oeesses are-preferably SQf.l3 fiIld.IlQl1- j resilient so that;.asthe nesult ot the execue .ti n .ot e.prec ssjth yrare l t me 901111 .tact with themicasheets; their surfaces ill-j. id estaeketshe b ng e f number of... the selections got. the; material- ..smck led l' t d fi em'e'eehifaces anaqgnnieetd tbg etlier m ser'ies .to coni ,mois ture and vvaa Iand-sealed; from the ,out-. 5' side, atmosphere. ;'I here f ore I prefer. lead s i .(se t m s k ew s ii f ,trad e') ,falthou h not only. maytherebe used:
1- s tzm t l; tQi-J jl iQ L P-PQT .tlii lter puahz to be sufficiently non-resilient,-.but,.tl1e foils Q themselves may .have some, degree of resili- 1 :ence althoughg that is not g$0' desirable,
.-.char:1cterg ofgsuchfoil sheets, they exert no tcndcncyto force ,theshccts apart after they have been compressed together, and the rcsultantcondensers Wlll consist of mica and foil sheets compressed .into persistently intinulie Contact with each" other without any mzl. lantial intervention. ofwan whichlms tion of the process of construction as an agent for washing, out air and moisture from I betr on the sheets. The condenser is -permanently compressed mechanically to main- -15 tain the above COIlClltlOIl. and to the same end permanently embedded in a mass of suitablev paraffin; the. condenser prior tozsuch ,cmbedding being sulnected to the highest practicable. compression, so. that ,the. treat 5e ment during manufacture and the permanent compressing and embedding I serve respec tively to eliminate froinand prevent re-entry intothe interior :of the stack of materials foreign. to the mica and fo lgsheel's.
Ring iframe exi tfid between th e sheet's during the eziecu-f The invention consists injc'ertain of the stepsof the processes described herein and ,in certain .combintion's of {such-steps, in the [improved condenser itselLT-and in certain features of apparatus mp1oyed, ,au s' will Figl (i is. an: elevation showy g} lthe' coins .pr e'ssio n of the material-stackin the pressafter removal from the bath .of
. Fig. .7,is ,elevationof part of u etmaterial-stack .which .has been. selected there from. for use in or as a. condens eij staclc Fig' 8 s an'; e1 ev,auoa or assem led condenser stac'k fmf condenser consisting. of a or'E eiicjaia n' mba-baaga em anthe end b ea aw- Qwing. ,to the;soft inertpor. non-resilient .,dotted.lines, Fig.19) a s in serted in todts perinanent container or casing, the: condenser an, d casing being highly, .comp ressecltogether ;in a spring press inFig. 9-,{anda temporary ialsehead beingi sec u redlto the top .of the casing. f
, Fig. 11 isla detail offlthe leafv spring forming apart of the press oi Fig.9. l
Figfli is an elevation showings form of permanent spring clamp ,for the condenser.
F ig.. 13 diagrammatic planoflappm ratus involving a vacuuin tank in. which is inserted-the apparatus of Fig. 9. and "a wax -reservoir or paraffin tank connected by pipes to the vacuum tank for the purpose of filling thecondenser easing with embedding, paraflin.
Fig. 14: is an elevation of appa-rtaus employed in the special process of cooling the embedding .parafi in in the'condens r casing.
' Fig. 15 is an elevation, partly in section, of the condenser casing of Fig. l.0.containing the einbeclment and condenserpwith casing coi er in place.
. While aiiy ltiiid -o t wart o'i Tsiniila r Int (lethal may be employed in this inventioinneverthe less parufiin vax is very highly preferable as being specially adapted to the gnoeesses and product hereof. Also a small percentage (say five per cent more or less) of carnauba wax or waxes possessing'similar properties is mixed with the paraffin. The addition of the carna ub a vim the "melting point of the mixture and when cooled provides a ha'rilet niiitelrial ferth'e condenser "eir'ihediiieiit. This "specification of "wait refers to the wax used iii 'aIl the steps "ot the 'j'roc'esses. wherever tfefeiite is 'liere rha'ftdit0 parafih1"a ltine,it is'f'to be "undei'stood as 'ip'r'eferably inclfitlingthcsitiall perc'enti-i ir'eot car- 'Tiiiiibi wax. The waxilsc d in all the proi. sscs hereof is preterably ie-watery iirmn moisture-as by'heatingitto froin 100 centit rdde'toism "C. M The condenset'stnatle by 'tlie pi'ocesse ereare "n'i'oi'e' 'ii-rtichlarly atlaptetl fbi use "iintlc'ncdntliti 'it is fiflrptiititht that there shall be miniih'urti el'e'ctiicallb'sses in the condetise'r in ervice's: itii'atliotelegraph 'tthhitiitt'ers 61 iii "powct lines, laboratory standards antl theli'ke Tlieeontleii'ser seek, in any case, may be employed as a unit in any "desired way,6r it Iniiybeconstructed in sections whielFnuiy be girtihped ih'serVi'ce in any desired reldtionfbfsrie's, parallel or seriesparallel, or the eond'fis'r' ftiay bec iinstriicted intofs'ect ionspermanently connected i'n'sel' ics, 'zis in the radio telegraph transmitting use e ite-i t'he coil(liifsr is not oiil constructed withseetieti's iiisi lat etl fremcne' another; at their end faces, the well-k iiown way, but the sections are "permanently connected in series in the well-known manner via foils projecting frtimthe'stack-sides.
Inkpre'pai'atiiihforthejprocesses, the sheets of'niica and toihare' 'cut to whatei-er sizes Iii'ayhe desired rm a particular design of coudehser, 'i'hdfoil sheets beiiiig usually longer and harrowerthan the mica sheets as in the culinary sheet condenser. The toil sheets are wlled to be perfectly flat, and the mica. sneets are tested, dried. and stored ih'air-tiigiht coutainers to await execution ofthe processes-1. As the first process, allthe sheets, of both mien-end foil, arec'oa'ted with the pai'allin 'which'serves lati asail'el'crfJeht for-hashing riiitziir and inoistiite 'troin hetween the assemhled sheets,later steps being: employed for the purpose of squeezing outthis paraliin fi-mn hetu'een'the slieetst'o the gr atest poss ble eiztentwith the View o f"l"e:ivin.9; a condenser stack consisting only of the sheets of mica an'dloil, preferably freed frbniall the par'afiin whichhas been temporarily niployed for the purpose of Was-inn} out the other undesired foi eig ji in:iteriiils,"i. air and nioisone. This bearish-may be donehy treiiting the loosely-assembled sheets' to a heth oi hot paraflin; but the greatly preferred process is that o' t separatelycoating each sheet with the parafiin, this being done preferably While the process ofbuilding up the material-stack out of the separate sheets is being effected, this preterenee beiiifg' due'to the 'tactthat the sheets udien ivet ii'ithpai'a'fiinaie "much more conveniently held together at this stage of the processes than when dry. At this stage, thest'ac'k i's'called 'the material-stack because it constitutes the material out of which the dvtittia'l condenser 's'tac'k (or simply condenser) is tob'e' made as by sele'ct'ing'a sufiicieht "length 'or Inegths of the 'iuateriahstack 'ithichh'as or liave electrical capacity suitable for the condenser.
Fig. 1, in "elevation, shows the building stand consisting of horizerital metal plate 1, two eerie-a1passa e-the rear. each-of these posts being-eat away at-8 to alihe'and guide he sheets of '1ni'ca=tlurinf1 the'operation of building the material-stack,and four legs l'a'reprovided on the bottom 1.
Figs. 2 and. 3 show the building stand of Fi 1' inserted in a waxing tray'5, the latter bciiifi heated by a. very mall lhinseh burner -6 (Fig.3) tofkeep simpl warm the paraflin intlie tray. Ilhstbetore each sheet of In'icaor foil is'plac'ed first on top of thebase 1 and then on top of oneanother alternately, the operator dips eachsu'ch sheet inthe paraffin in tray '5- and then places it onthe growing stack shown'in Figs? and 3. 'As stated, the
cut away portions of posts 2 aline the mica sheets 7'asishewn in Fig. 2. Then'ontop 0t each coated niiba sheet ispla'ced a co'ated foil sheet as8,'the tirst foilsheetb'eing'placed say so thatits leftfiroj'ectsto the left (it the mica sh'et 7, but at its right it does not extend to 'tl'ieedgc Git-he inicasheet 'i. Then another coated r'n'ica sheet-is placed exactly on topof the first foil sheet 7. heing alined therewith by the cut away portions 3 of the 'posts Then the 'ne'xt. coated foil sheet as 9 is'placed on top of the lasti'nica. sheet llut extending to the right beyond the mica sheet and at its left not. extend ing to the left end of the mica sheet. As'the operator puts each foil sheet in place, she cana'iid should ol'rservc Whether any air bubble is entrained in the parailin (due possibly to incomplete dipping), and it there be, or preferably in ever ease,'she su'ioeths down (squeegees) each foil to squeeze out the air. Likewise, in pet-ting each dipped mica sheet in place, she prcsses it dawn on the coated foil sheet beneath it, for the same purpose of squeezingout air. Thus the material-stack is built up ofalternated sheets of mica and toil, while the si1cce's sive'f0il sheets are placed so as to'eritend respectively at opposite ends of the stack and overlap one another (although separated'by a mica sheet) in the central part (lift 1B'illfiSiOfltllG mica sheets in the stack. "lhehott oin "1 of the building stand (Figs. 1 and 2)"is set down in the body of liquid paratfin in tray 5, so that it is heated by the parafkept warm, i. e., both by the Warm coatings I on the respective sheets and by the heat conducted from the warm parafiin in tray by the metal base 1 and metal'posts 2and conducted upwardly'by the growing stackjitself. This maintenance of warming. during building assists in keeping #down unnecessary thickness of; the :coating paraffin 1 between sheets (due to theincreasing tendency of the 1 growing stack to squeeze out excess pa'raflin. by gravi-ty)-' and-also assists in tending to av'oid 'theentrapping of air'inlthe stack at this stage (due to the tendency togreater intimacy of the sheets and theconsequent tendenc'y fto cause-the liquid parafin to wash out --air' and moisture from between the sheets rather than to permit entrance or entrapping betweenthe 'sheets).""-If the material-stack during the'building operation becomes insufficient-ly Warm, orif it hardens'as appears to the operators eye, she may spoon up parafiin from tray-5 and pour it over the material stack from{ti'me to time fo'r'thef purpose of keeping warm andsoft the paraffin between the-sheets. J: ;.:a p
Tli'e "material-stack may be bu1lt-completely undera bath-of l'pa'rafiin, but as described above it is usuallybuilt-in atmosphere with its lower end "in heat; conducting relationwith'the parafin intrayfi, which causes less exposure of the'ope'rators fingers to the heated Y paraflina lt' is i immaterial that the small corner's or edgesof the .sheets which are held in'gthe operators fingers during the dipping operation be not-coated with the paraffin, for the dipping and building operations'leave suflicicnt paraifin' on thefsheet's s0 that-inthe building operation itself and espe cially during the subsequent squeezing or washing out operation the entire surfaces of the sheets are washed of air and moisture hy the outgoing-paraflin, it not being the object of the invention to retain-any paraffin permanently on the sheets. 'Ihe'temperature of the parafiin in building tray 5 during the coating and building operation 'is'about centigrade, i. e., about the temperature the operators fingers will conveniently stand.
During the building operation, in case the eventual condenser is to consist of a number of separate sections, temporary section separators of metal or any other desired material may be inserted 'as a convenient method of separating the sections in the materialstack, particularly if during the building operation pains are taken to insure that each section has the same electrical capacity, as by using material of uniform thickness for the :mica sheets and byinserting the temporary ing at substantially separators or markers above the same number of mica sheets for each section.
After the imiterial-stack is built to the capacity of the building stand of Figs. 1, 2 and :5, it is allowed to cool therein sufficiently to permit convenient handling without impairing the unitary character of the stack consisting of the sheets temporarily held in alinement by the paraliin coatings, and then transferred to the so-called pressing frame shown in Fig. 4. .This frame consists of a substantial metal base 10 with four upright metal posts 11 at the four corners thereof. Each of the four posts 11 is provided with cut away portions 12 like the cut away portions 3 of the posts 2 of Fig. l, to aline the four corners of the mica sheets in the stack. When the n'iaterial-stack is inserted in this pressing frame, the foil sheets project out-at bothends of the stack between the vertical posts 11, the cut away portions 12 of the posts 11 serving to hold all the mica sheets in alinement as stated. After the materialstackis inserted in this pressing frame, a plate 10' with four holes for the four posts 11 is slipped down over. the said posts and upon the top of the stack. On plate 13 is placed a plate 13 between the posts 11, to serve in a later step as a temporary compressing member on the stack, the base 10 of the pres. g'framc. This plate 13 has a central depression 13 for use in manner to be described later.
The next step consists in inserting the pressing frame containing the material stack into a bath of hot-molten paraffin in a temporary container 14 (Fig. 5). During this bath, the container is heated by the flame of an'ordinary Bunsen burner 15. In this step, the paraflin coatings on the sheets which yet remain as thin layers licti-x'a-en sheets in the material stack are completely liquefied. This heating bath is maintained for about twenty minutes, the temperature of the parafiin hol35 C. iiy the time the material-stack is thoroughly iwahwl, some of the moisture remaining with the parailin between the sheets inside the stack becomes vaporized and escapes from the stuck into the bath. Such moisture that which may have been entrapped in the coating parafiin during the dipping and building operation when the parafiin was not at so high a temperature as in this bath, i. e., being then preferably less than 100 C.
Upon completion of the treatment of the material-stack in the heating hath, it is subjected to the highcs; practicable mechanical compression, by some such means as that shown in Fig. 6. This is a very important step in the process. It results in substantially completing the squeezing out of the thin paraffin layers between the sheets and thereby washing out from the interior of co-operatively with F ig. 7 where 21.and 22-indicate the respective bunches of foil ends at the opposite ends of being particularly adapted forl.a sectional .condenser. The single section of Fig. 7 however, may be permanently =clamped and used as a .complete. condenser, forits air-tight conditionwith mica and foil sheets closely compressed together. adapts itfor such final use; In the assembly of ig 8. are provided. insulating barriersorseparators 23 between 4 the-sections. These may be mica sheets.
ease temporary markers have beenused for the. sections j in; building the inaterial-stack, these insulators23 simply replace such mar kers.. In the assembly of Fig. 8 also, the sectionsare electrically connected. together by connections 24, .in the manner. long practiced for producing a. sectional "condenser (as shown), and, of course, .as. usual, theseparators 23 project onlyat one end of the con:
denser where the sections are at different po tentials .and require insulation from'on'e-aib other and where there are 110 connections between the sections. In practice, these connec 'tions 24. are constituted simply-by" soldering together, adjacent bunches fo'f 'toiliends. At
this point, if ny processes have been care: fully. followed, the condition of each section willbe thesameas the condition of the com:
"pleted material-stack, i. e., each section isin such conditionihatit might be used alone as a condenser. v Thesubsequ'ent .treatrnentf of the assembled sectional condenser-of, Fig. 8 (to be described in connection with Figs. 9 and 10) isthat simply-which is. desirable to put the assembly into the same said condition as is each section and. also to insure the maintenanceof such condition as by a permanent embedding in p'arafiin. p y f Y In Figs. 9 and' lO (elevation and plan respectively) is'shown part of the apparatus for such further treatment, and in Fig. 11 is shown a detail of the leaf spring employed.
In Figs. 9 and 10, the condenserstack 25, shown in dotted lines in Fig 9, has been inserted in its final metal casing 26. At this stage, the condenser has placedon its top its final stud plate 27. (Fig. 8), with high potential terminal or stud 26' mounted therewith and projecting upwardly, and conducting strip leads 41 connected to the foil-hunches of oppositepotential staclesections as in Figs.
12 and 15. On top of the casing 26 is secured by screws a temporary head 29, provided;
with a cross piece 30, (Fig 10) having a central opening up through which projects the stud terminal 28. This serves to center the condenser 25 in its casing 26; and this temporary head 29 ser'ves'to receive the parleaf spring 37, as shown in Fig. l1.
afiin which is afterwards filled in around the condenser in its casing. Theentire casing 26 is mounted in the press shown in Fig. 9, said press consisting of top and bottom plates 31 and. 32, held together by bars 33 and 34 threaded at their ends and provided with nuts which hold the frame together. At the .center of the top member 31 is a screw 35 which extends down through a threaded hole in top plate 31, and'is provided with asuitable handle 36. 1 In series between the clamp screw 35 and the condenser terminal 28 is inserted a This spring consists of two-leaves bolted together at their ends and drilled with the central holes 38 and 39 to receive respcctively'the clampscrew 35 and condenser terminal 28..
. Thereupomby handle 36 thecondenser 25 is clamped against the bottom of its casing 26, which restson the bottom plate 32 of the press. This spring clamping is an importantf'unction which will be referred to. This clamp is shown in side ele atien in Fig. 14:. By-mea'ns of the clamping in thispress, the same highest practicable coi'npr'ession is ob tained on the assembled condenser as'was ini tially obtained by the clamping of the materialestack 6) and as was maintained on the material-stack and on its sections after rcmoval .of theclamp from the material-stack. In other wo'rds, by means of the clamp of Figs. 9 andil the sections of the assembly are now compresed together with the highest practicable mechanical compression. The. condenser stack 25 in its casing 26 with clamp applied as shown in Fig. 9, is now subjecti ed to aprocess of pre-heating preliminary to the embedding operation. As shown in Figs. 9 and 10', the temporary head 29 is open at its top save for the cross member 30 (Fig. 10), and has ,onlyside walls to constitute an.u.p-' ward extension of the side walls of -casing 26.
The process of pro-heating consists in pouring hot; wax throughsaid head down into the space in casing 26 around the condenser 25, until'both casing and head'are filled; and thereafter, and while this parafiin is in the casingandhead the heat of a Bunsen burner fiame'is applied to the bottom of the casing (similarlyto Fig. 5) for the purpose of cooperating in heating thoroughly the casing and condenser 25, this latter being done by playing the gas flame around the exterior of the casing. This gas flame may be applied to the casing prior to the pouring in of the paratlin, but if that be done care should be taken that such application be not caress-ire on account of the-possibility of overheating and carbonizing the parafiin'sheath or marginal paratiin around the condenser, and of melting the soldered connections of the condenser sections, which should not be heated as high as 150 C. I I
The hot parafiin in the casing serves to thoroughly heat the condenser itself, thereby condenser is thoroughly heated and itsseud para'ffin liquefied, the hezitingbath ofparafiin 1S pourecl out oflt'he easing head 29, by an inuersion ofthe en reejgpa-rntus ofiFij 9 The condenser noiv readyifor its final parafiin-embedinent in: its c'q' sing, in an instnnce wliene the ca sing, .to he provided with acovenserying piartof'a inennsto per nanentlyconipresjsjthe condenser within the ens ing.
clamp small enou to enter t he jfi nal conense as g, sneer; ndepen e t O f the .cl singe si Permit ie use 9f", permanentclg np' 'in res l ent form,, s ueh relkefihm n j SPJQXiilQlfok; he G9 edenser .1 foi-en liasheeni l, i c j st abort)? desqr 'tied,tlwtiislusih P r a ,spiii'ng clampiisjt i b enn l eli o t e condenser emerges-teeny t i laeeg he s'em cl'fcolil'fit 'penesi ym ae' iusukitiaigcoinn e s onlblhc'k 12,311M1i 1!. b ttom.
com pressing block 4.3 i 1f ijc1rmeybQ. oifmetall. The to p insulilt-ihg block lzgi'n ybe of; l; i,te or :1 Li y other suitable, insulator; which will, withstzuid the trealnncntiin'hot parnflihnniltl 1c 11 i gh; mechanical, compression involivcd'in n: y p rocesses, The fuont of the condenser 25 shown.
in Fig, 12 isone ql ithesides oi; the assembly and ntwhich the series connections are made and from which. pnejeetthevzs pntar iilg in;
u a sflifl; i'Fig- 8-. To. thelotlier twinned fiat sides of the ondenser, e lthje, sides formed vo,f.the edges. ofthe. miizfiishefets, 12).,m1e placed sgacing blocks Miami 4A of? insulating material s'imilzir to, thahoftop insulating, block These s de. sulat ng hloeks44 and e lt seme to, 'keep thestack in al'inement and also to fill the space'beneatl'i the high compression of the press before the $9 the P f i ting- 2 anflfii), f m s top nd the top block 42 zind to provide surfaces over which pass the wire 45, which constitutes the resilient clamp. This, wire consists n-eterably of piano steel wire and is wound tightly arounclthis assembly, as shownin Fig-'12;
while the assembly is maintained under the highest practicable, mechanical compression as-in any suitable temporary clamp or press,
such as aiC-clzunp, n visa, or any other suitable form of press, such, for exn'niple, :isthat shown in Fig, (3. While the assembly is under, such compression, the wire 45 is wound withflits turns tigl'itlj larou'nd the assembly audits ends fastened; securely to inein'tiiin same is ren'iov edi'Tfhe'eileot"oi the windhig;
I V, l i I M A off'thiswire45is cuinul zitivqeach tti rn'ilddin g lee insta e, hem Yer, w i sn; the corn. ,de'nser 18,110 beplovifded with aperinancnt to the efliect of the others inserYi-ng to increase the, tension on the assembly; The insulating; members 42, 44: and A l serve-t0 insulate the wire $5 from the and p revent electricnli connection between 'the two e nds of the stack whi'clr'are efo'ppo'site potential The com: prc ssion on, the stack is, of course, longitudinalihetween the top insul'a't ing plnteego-11d the bottom, eonipression jp lnte 43;. above compression fliectcdWVhile the j'contler iser is cold; .l'hereuponthe condenser, with its sn nll' elgn np applied, be 1-e1noved, 'fi oin the large press'i 'nditlr'oroughly heated, in a. bath of, parafljn ,at' about:13 5 C.' for about twenty minutes the result being .to thereby hent the condenser and liquef-j the marginal, ara-fin IL andiabout the condenser. This heating bath is prel'irninziny to a further coin-j pression, but it also servesto drive out of'and' oil from the condenser any or moisture Whichmey ha ve been'introduced into. the marginal sincethe production ofthe condenser from theniaierial steek or since the air and moisture were first-previously washed out from the materiel-stack. Pf the eohl'compression j'ust preyi'ous to ,thlis heating bath be omitted. i. c. ifthe condenser be subjected-to the healing bath without, being under. sirbstnntin l compression, then the Yzilne may be lost 01 the advantages of the originnlliot comprcssion of the material-stack, ii 0., the sub-, stnntiul washin out oi. 'fl.l1',.U)'ol moisture from between the sheets in the interior oflhe stzn-k.v As the result olfrthis, heating bnlh, all the pornfii'n )fltl'clllililllllg in and about the eondenser (and ,ztt this stage there is. very little, if-ztny, parafiin left inside the condenser) is lixpi'eli'ed'. The hot staclnyetsznl ahurVshercafter under compression, is then removed fro n'..tl i e heatig both end. returned to the P i lIl clfe i ijpv 0.1- erbor pr y the coin lressioiris egnin applied, but to a degree higher, than, when, the conclenscr was cold. lThijle under the high compression of the press the ermenent small-clamp 4'5 is turther thghtenei, to maintain the compression at. tained the large clamp or press, which at this stage should have been set for about one thousand pounds per square inch of active area of the overlapping portions of the foil sheets in the centre of the condenser. Such increase of compression and the further tight ening of the permanent clamp are permitted when at this stage there is any paraiiin remaining inside the stack as between the sections, such paraffin being of course soft as the result of the heating bath. Upon the tighte n ing up (or rewinding) of the small permanent clamp, the condenser is removed from the large clamp or press. This operation,which is the final operation on the condenser stacl-z itself, has resulted in yet more completely squeezing out any paratlin remaining between the sheets in the condenser and therefore in washing out any remaining air or moisture vapor within such parafiin. After the application of any such permanent spring clamp as in Fig. 12, the assembly of Fig. 12, which is the final complete condenser in an electrical sense, is placed in the casing 26 of Fig. 10, together with the temporary head 29 for the pre-heating preliminary to final embedding, which already has been described in connection with Figs. 9 and 10; but the clamping appa ratus in Fig. 9 will not be needed now because the wire to of F ig. 12 already serves to provide the high resilient compression of the leaf spring clamp apparatus of Fig. 9. However. the top lead 40 (Fig. l5) may be connected to the condenser terminal 28 (Figs. 12 and 15), the latter being centered through ,the opening in the head 29 of Fig. 9, in order to center the condenser of Fig. 12 in the easing 26 of Fig. 9.
lVhether there be used in the process first above described in connection with Figs. 9 and 10, the condenser of 9 with the temporary leaf spring 37, or the condenser of Fig. 19. with a permanent resilient clamp as 45, for example, the effectof the. resilient compression during the healing bath in the casing 26 of Fig. 9 will he the same, i. 0., when the condenser cxpands during the process of preheating in the paraliin bath in the casing at; of Fig. 9. the. resilient chimp will yield to prevent dcl'ormatiou of or injury to the stack, and at all times t'lurcnitcl during the. process (and tlnrren'ller in servi e in the case of the permanent clamp of Fig. 12) the springciainp will yieid during the lli the cox-ling to conform to the length of flu sla k and at all times uniformly exert the desired uniform high compression.
'lhcreupon, in the case oi the condenser of Fig. 9 or the condenser ol- Fig. 12, after the prc-lurating bath of parail'in of Figs. 9 and 10 is poured oil from the casing 26, the assembly of the casing, condenser and spring clamp (i. 0.. either the temporary leaf spring clamp of Fig. 9 or the permanent sgring clamp of Fig. 12) is inserted in the apparatus of Fig. 13 for the purpose of being subjected to the production of the permanent embedment of the condenser in hot parafiin preliminary to the final stage of cooling. For this purpose one or more-of such assemblages (two as shown in Fig. 13) are placed in-tank 46, which is used primarily as avacuum tank, tube 47 I ed the preceding parafiin heating bath and a while the stack is yeta-s hot as possible, and the subjection to the vacuum treatment should also be effected immediately. This vacuum should be a fairly higlrvaeu'um of the order of a few millimeters, atpreferably not much higher pressure than 3 millimeters. The vacuum treatment need not be applied to the stack for more than a -few minutes, because it does no good save while the stack is hot and its marginal wax is liquefied or soft, the obj ect of the vacuum treatment being to remove air and moisture from the liquid or softmarginal wax in preparation for the process next to be effected, of enveloping the stack in hot. paraffim for eventual cooling and embedment.
All this time thestack is under the abovedescribed mechanical compression of either the leaf spring 37 of Fig. 9 or the permanent spring clamp 45 of Fig. 12. I
\Vhile the vacuum is yet applied to the condensers in the tank 4 6, hot paraflin for the permanent embedding is flowed in around the condenser in each casing until not only is the stack completely submerged in the paraffin, but the head 29 also,(Fi g. 9). ontop of the casing above thelsta'ek is completely filled with the hot'parafiin', so that a fluid head of molten parafiin is established above that part of the filler which lies in the vicinity of the insulating portion of the casing and of the neighboring metal parts of the casing and high potential terminal. The maintenance of the vacuum around the stack until the latter is submerged in the parailin serves to prevent the entrapping of any air or gaseous vapor in any portions of the final embedding parallin, which may be so close to the condenser as to permit electrical losses or breakdowns in service due to such air or moisture. \Vhile the hot embedding parafiin is being flowed into the exhausted space around the con-- denser, the air or vapor which may have been in the marginal paratlin of the condenser and which has been removed therefrom by the vacuum and attenuated and distributed through the vacnous space in the tank is prevented by the continuation of the vacuum from being concentrated or entering again into the marginal wax. Thus, the 'inflowiug parafiin from pipes 49, branching from pipe 50, connected to paratlm reservoir 51, can, upon entering the condenser casings, merge with the hot. marginal condenser parafiin freed of air and moisture, the incoming parafiin having been also freed of air and inois ion Ill)
eser oi 51. tank 6 condenser is, desired these processes o f yapnnm and filling-in embedding .parefl n While under vacuum are extremely important. I
An equalizer pipe-6 3 is connected between the wax reservoir 511411111 the tank 46. Its
function-is to make theg'as pressure on wax in rcser-vrnrfil atwall tunes equal to tha t -1n tank 46, the reservoir 5ibeingpifoyidedwith an air-tightcover-'65. Then rega rdless o2 any application Qf'vacnn n (or-air pressnre) to;tan k 21-6., the. pein'ifml wil fle fi' em, we t atfect ngitliepperation'of'my-lprocesses.fl""
voir 7 51 into' the cond a $6 uml i Y i t hea g ven. by
tinsel n if? Vacuum v :ibnal nl t equ liz r Din G3ft 63' out of service desired, .v'alvefil being then turned to open the reservoir ,61
to the-atmosphere. The other or norinal posiion of valve si nply pl aces 1n co nm nny cation with one anotherthe lair-spaces n At anytillip fitter tlielilfiowingparaliin has s bmerged he C ndens n -its easing. the vacn ni treatment can be terminated by] e lo. .i 1ig f al e 1 in thel uheft th f vacuum ,i lp, a d by, th qpeein eat-fli k e c' iwl e 1211 thePiP atlt er sli ii em:
em. du ing the, p'ana fi fill es fl e -e i1.'enent or .vap or .which has cerneffrom the stack or innrjcating'withthe outside air.
incidentally fro rn the inflowing plarefiing,
tank 4 6 on account of the greatly rediieed pressure on the parai'fin-due to the acunni,
will haverisen up through the hotparaflin in the condenser easing topointsat or near its surface, where it .n ay exist in the form of foam or iroth justbelow the surface. Thereupon these bubbles jnstbenea-th the surface will-break through the surface and disappear in thespaee in the tank. Therefore; it is preferable not to shut off the main paratiin valve 53 until afterthis frothhas disappeared and. therefore until aller both the casiru and the head 29 are completely filled with paraffin Sllbbiillltlilli) freed of air. Prelerably also the wire 52 is not opened to let the outside air intotanli d6 nntil eifter saidfilling has been completed.
After main paraffin valve 53 has been closed, and hefor e'blceder alve 52 is opened,
and 'before paralfin has solidified in pipes.
49, Valve fl-is opened inpipe (the end of which is open toithe atmosphere), in order to causeatmospheric pressure to force paraffi i reniaining'in pipes 419 against-therednced helcl i tie le t reservoir 51 above tank 46.1 llnis; the m a fin may flow by gravity 'f en ese -Y0i. f 51f to the condenser x,caminfgs 151,6, "i rtefl pr Ct-iv 0f the ai pr ssiu-eln the lett r? HID" *iplaee i= new;
'Il drtaizit in'anycaisew he're' 'i erl-t i hav t e 1 d holosteric,i. effreed fofell. birds I lhi s"p1:oc css" consists ein ffcertaiii reatr nent xirliieh" is applied daring ofthepiraf fi'n inside the casing- 26nndhead.a29; This treatment consists; fgenerally speaking, in li y egi h He e d n i mifi emi bottorn ;np\i ards '1; "e; the bottoni more "theitop zill "a, p q ive'i enne- E l s ay'rhmfi e either y "("1)"e treizfi n f etfi 'th' 1 tom without nythin to the topparal';
o lpwa s lb wmfi mp rt f r- 3*) y ab an i, iii ti t m"e' i 1m h p ly g he;
;Si eny; we latter isP'r'ef 'rabIe' f r'beonpi fof "time and n'e li t tlo 'e the s i e ii tibn of the ;process. In pract1ee,jthe "last or preferable manner has heenleffeictedhy i n. sorting the condensereas'ing 26 inv a shalle W pan or tray 55 Containii g nater, which may be renewed from tinie'to time; or (consists of water circulation. Alternatively and preferably, an air blast; from blower 56 1nay be directed againstthe lower portions of the sides and the b ottorn of casing 26 in the absence of Water tray 55. The air blast may be directed against the desired lower portions of casing 26 by means of flexible tubing 57. And, as part of said preferred .manner of ex ecuting the process of gradual cooling from the bottom upwards, the npper part of the liquid paratlin bodyfin casing 26 andhead29 may be and has beensuccessfiilly in practice, heated as by-peuringin additional hotpal-at fin f om. tim to imelwhk'h," ind d, i useful also to con pensetefor the shrinkage of the parattin in the casing as its contracts due to its-temperature being lowered and to its solidification. 'The heating is elfected eddi: tionally, when desirei hy neans ota removable eloctrical heating coil 58 mounted circ mferentially around head 29; or alternatively with'such coil the flame of a Bunsen burner maybe played around the walls of head '29. and around the upper part of casing :26. I
In Fig, 14 is represented in dottcdlines the condenser with all of the temporary clam ping apparatus of Fig. 9, including the leaf sp r ing 3'(j but whenthe permanent spring ela 1 np of -,Fig. 12is used,.such temporary apparatus willnot be used, and the appai atus subjected to the cooling treatment of Eig. 14 will consist simply of the condenser casing 26 containingcondenser 25 in ifs'spr'ing clamp 45 of Fig.12, and thetcmpora yhead 29, heatingcoil-58, and any of the described means for abstracting heat from thelowerlportion of the liquid paraffin in the condensercasing, and adding heat to the top.
The importance ofthis cooling treatmentgradually from the bottom upwards, particularly in connection with the head 29 on top of easing 26,: or of. the equivalent of this pro s's'is due to the fact that the cooling of paraffin or any substantial equivalent waxes whichpcanbe used for these condensers is accompanied bya large decrease in volume, suclrthat without this process an ordinary ornniform cooling from all sides would resultgjirst the cooling. of an exterior shell and the?cooling and contraction of the i11- tei'iorfvv hich would result in the formation of interior voids or cracks, which, in turn, might be filled with gases or vapors which had been entrained'jnthe paraffin or with atmosphere drawn urn-om outside the paraffin; and such ordinary processof solidification or freezing would result, as ordinarily, in the driving away from the surfaces of solidification towa rd the' central liquefied portions of all foreign materials, this central portion in the casingof a condenser being the stack itself, from which it is extremely desirable that all such foreign materials be removed as far as possible. With my process of cooling gradually from the bottom upwardly, the above action is avoided and on the contrary the surfaces of solidification, gradually moving upwardly, drive. before them all such foreign materials and, not only that, but force them up beyond the vicinity of the upper or high potential end of thecondcnscr and out of the casing 26 entirely further up into the paraflin contained in the head 29. Hence, the permanentcmbedding paraffin in the casing (as distinguished from the temporary paraffin in the temporary head 29) is made substantially solid. and voids otherwise tending to become fixed in the upper part of casing 26, in the neighborhood of the upper or high potential end of the condenser, are caused to be established, if anywhere, in the temporary paraffin in the temporary head 29. Also, the use of head 29 in connection with the repeated addilion of hot mraffiu to compensate for the shrinkage during cooling, prevents the formation of a final depression in the paraffin in the top of casing 26, so that the final cooling of the top of the paraffin in the casing results in a uniform mass of paraffin free from any lines of cleavage which might exist in the parafiin in the casing if it were allowed to solidify with a depression in its top surface and if after solidification additional paraffin were added to fill up the depression.
Upon the application of this solidification process, the paraffin commences to silidify at the bottom of the casing andat lower portions along the sides of the casing and the sides of the stack resting on the bottom-of the casing 26, the rest of the paraffin in the casing26 and head29'remaining liquid. As this cooling process iscontinued (which may be severalhours, depending upon the size of the condenser and depending upon the particular meansfor cooling and heating employed, the air blast above described being more efficient than the water cooling), the solidification extends h1gher.up from thebottom of the casing and still higher up inside the sides thereof and along the sides of the condenser, so that the remaining liquid paraffin is U-shaped in cross-section around the condenser.- Thus, as the solidification gradually extends upwardly, the liquefied r mainder at all times bears down u on and against .the upwardly moving sur aces of solidification and directly follows up the shrinkage or contraction at such surfaces accompanying the solidification, to the end of preventing voids or cracks. .-Meanwhile, as stated above, the surfacesof solidification drive upwardly any remauent air or moisture, not only to the upper part-of the casing 26, but up into the head 29. If'the head 29 be sufficiently high to contain a sufficient volume of paraffin, then all the air and moisture as well as voids finally forming near the upper surface of the paraflin will be contained wholly within the head, so that when later the temporary wax in the head 29 is cut off, there will be left no voids, air holes or depressions in the upper part of the casing in the vicinity of the condenser. In instances when the execution of this cooling process involves specifically the ap lication of heat (as in the preferred form) to the paraffin in the head 29, such application of heat may be discontinued after assurance is obtained by observatirm that solidification has been COlllph-ted of all the paraffin within the casing 26. It is to be understood that this cooling operation is conducted under at least atmospheric pressure, so that the atmosphere has access to the top of the molten paraffin in head 29, in order to assist in the cooling process in respect of the prevention of voids in the paraffin in casing 26. If desired, this air or gas pre sure o top f the molten paraffin body may be greatly increased above atmospheric pressure, this increased pressure being advan tageously as high as 1-50 pounds, which can be maintained until complete solidification has been eflected. The effect of such increased pressure is to com press any voids or bubbles in the pa rafiin. thereby making their effect less deleterious. For this purpose, the condenser in its filled casing may be left in ianlr- 16 of Fig. 13 for the execution of the cooling process, and con'lprcsscd air from asuitable pump may be introduced into the tank 46 hy'way'of valve 52. Also, the application of additional wasinto the head 29 during the cooling process may be effected by way of the pipes'49'irom the paraflin reservoir 51, in which case, of course, the paraffin in reservoir 5-1 shouldbe subjected to at least tl'iesa'megas pressure as-that of the tank 46 by way of val-ve-645, in-order to permit the inflow of paraflin intotank 46.
Throughout the above paraffin embedding process and'ever'since-the condenser stack has been assembled,- it has'beenunder the highest practicable mechanical compression either by way of atemporary rigid'clamp, a temporary spring clamp or a permanent spring clamp adapted to be received'w'iththe'staclt into the final condenser casing. If thefclamp be a temporary el'ainpas illustrated in Figs. 9 and 14, it isre'move'd upon the complete solidification of-the embedding parafiih; but when such temporary clamp is employed and duly removed, it sliould'be replaced with the clamp which is to be permanently assembled with the condenser in service, as soonas possible after the removal of the temporary clamp; for even although the embedding paraffin be completely solidified before the removal of the temporary clamp, such solid paraffin is liable to cold flow and, therefore, is liable to permit expansion of the stack under heating conditions which may be encountered in service. andthis-should never be permitted. For this reason, it is preferable, as stated above,- to employ some such form of pern'ia-nent' cl'amp as that illustrated in Fig. 12. or anot her form of springclan'ip such as that. shown in my application, Serial No. 292,126, filed April 23, 1919; of which the present application is a continuation-in part, and such permanent clamp should be applied to the condenser at'the-earliest possible stage in the process, even at the stage when the stack has been treated to the parafiin bath as in Fig. 5, just before it is subjected to the washing out processillustrated in Fig. 6.
\Vith' further reference to Fig. 14'. After thesolid-ification of parafiin is completed, the head 29 is removed from the casing and from the paraflin in the head above the casing, this removal being readily permitted upon the applicatioirof heat from removable heater 58 cr'of a gasfiame tothe outside of the walls of head 29; Then, by means of a long knife applied to the condenser any suitable meansof permanently clamping it in its casing; for
example, a construction may be provided whereby the application of a coyei to the top of the casing' will serve in any well lmown manner to compress the condenscriiithe cas ing. Preferably, however, as when a permanent small clamp (as in Fig.' 12) is em ployedin the processes, such permanent'clam'p (as '59, Fig. is left on thecond'enser in the casing and any suitable cover '60 is applied to the top of the casing over the embedding parafiin. The modified form of small permanent clamp in the casing, which is shown in Fig. 15, comprises a' U shaped steel yoke 59 which elnbraces'the condenser. The U cnd is insulatedfrom the condenser as by a: stack of mica sl1cets 62. Two of these clamps are disposedsymmetrically on the condenser. The two ends of each clan'ip are entered by adjusting screws 61 which pass up through a steel spring plate 43* (common to both clan'ips), whereby plate 43"? is flexed to apply the desired compression. Mica stat-E662 is placed on top of insulating'plate' (3ft (as of balielit'e) which in turn rests onf metal plate 27 which transmits the pressure of Insulating the clamps 59 to the condenser. plate 66' insulates the lead from the top of the condenser) The condenser terminal 28 is'soldered atits bottom to the upper end of strip lead 40. l
The condenser terminals may be brought out through the casing "in any desirable or well-known manner-as (Fig. 15) the high potential terminal 28 through'an opening in insulating cover and one terminal (that of low potential) may be constituted" by the metal casing 26 itself. pursuant to the common practice.
The above advantages of the embedding and cooling operations may be obtained, it desired, by providing a threaded opening'it) and a plug 71 therefor in the bottom of the casing for the inflowing of embedding parafiin, the casing (with its final cover applied and connection or connections made therethrough) being inverted during the filling and cooling operations, and after solidification, the bottom opening closed up. By such an operation, one may avoidthe use of the temporary head 29 (Fig. 9), for the condenser would be centered in its casing by assembly with the cover of therasing (Fig. 15) the assembled condenser and cover being applied in and to the casing; and the filling of the space in the inverted casing produces an even higher fluid'head on thefiller in the v1- cinity of the higlrpotential insulating portion of the casing than is obtained by temporary head 29 of Fig. 29. Thus, with the casing with cover applied (Fig. 15), but inverted during filling and solidification, and the high potential terminal-end of the coir denser (top Fig. 15) lvin'g in'what is temporarily the bottom of the container of liquid paraffin (Fig. 14),}1'nk1 the-supply of heat to the upper portion "of the tiller, the paraffin begins to cool at the bottom around 'the'high potential end of the "condenser, and the parafiin thereabove bears down on the upwardly extending surfaces of solidification, thereby preventingthe formation'of voids or cracks near the high'potential end; and anycra'cks' or' voids in the. paraffin 'near the lowv potentialendiof the condenser would be relativel "innocuous. "Al-so the paraffin by this met 0d is caused to adhere to the inside surface of the cover'of a casing, as the result of being applied thereto when hot and molten. This condition of the insulatingwax at the neighboring condenser/portions of high potential differenc'e a's'sists in'preventing elec'* trical' brushing, freduces the tendeney to creepage and prevents absorption" of moisture at locations where :mois'turei would produce serious resultsf H YVhen a ermanent condenser clamp is rope'rl'yfand permanentused' or the st'acli is lyicla mped'iiiside e'casing any means, it is not soj'impor'tant that the foil sheets be non iiesilient, for sucli'c lamp' at a fsufiiciently early stage inthe process willserve to main; tain the' desired intimacy of contact between mica and foil sli'eetsfwhich excludes, everything foreign from" between the 'slieets. And even when a permanent eondenserclamp be not'used, the foil sheets' mayhave some de gree of resiliency with-out resulting inbreaking down the hermetical sealing by the marginal she'atli' parafiinfespecially if the stack in 'th'e earl ta'ge's of the process have a sufficient thickness ofn ai g'iual sheath to prevent expansion "of the stack' (laterally with respect to the stack), and this may be obtained if necessary by suitable dipping in the paraffin bath fort-he purpose ofohtaining such substantial thickness of the marginal paraffin.
\Vhenevcr compression or clamps are refcrred to herein, such compression is to be understood to he the highest mechanical compression which is practicable to be applied on the soft lead-foil sheets, and this in practice is about 1,000 pounds or more per square inch of the active area of'each mica sheet, i. 0., that part of the mica sheet which lies betwecn theovcrlapping 'foil sheets, this being a pressure which amounts to about 'a ton or more on the entire end surface of an ordinary condenser 3"lliig'h by 2 long by 1%" wide.
\Vhen the word paraffin is used in the claims, it is intended as applying to any material which is the substantial equivalent of the parafiin-carnauba mixture preferred herein. As to the limitation to sheets of mica, it is to he understood that this does not exclude other materials which might be. found to be equivalent within the invention. as to the valuable properties of mica for this purpose involving its low dielectric losses, its nonporous character, its ability to be formed into thin sheets of sutiicient mechanical strength for my processes, and its high di electric constant which permits production of a high capacity condenser of small volume.
I claim l. The method of making an electrical condenser stack of non-porous dielectric sheets and metal sheets which consists in first coating the active non-porous surfaces of the sheets, prior to stacking them together, with a dielectric detergent liquid; thereafter stacking the sheets; and thereafter employing the detergent layers between the sheets in the stack to Wash out air or mo sture from he tween the sheets, by squeezing the sheets together when the detergent layers are liquid, thereby forcing out said layers with any entrained air or moisture from between adjacent sheets and permitting the non-porous surfaces of adjacent pairs of sheets, so freed of air and moisture between them, to lie together in intimate surface contact with one another in the stack.
I 2. The method of making an electrical condenser stack of non-porous dielectric sheets and metal sheets which consists in causing the sheets to {adheretogether" during the stackingloperation by'first coating their actire non-porous surfaces, prior-to stacking, with normally solid dielectric detergent in hot' inoltencondition thereafter 7 stacking the sheets't-ogether when the coating on at least one of the facing surfaces of two adjacent sheets is warm enough to cause adherence of such surfaccsi' and subsequent to stacking, employing the detergent layers between the shects in the stack to wash out air or moisture from between the sheets. b squeezing the sheets together when the detergent layers are liquid.'thcreb "forcing out said layers with any entraincf l' air or moisture from between adjacent sheets and permitting the non-porous surfaces of adjacent pairs of sheets, so freed of air and moisture between them. to lie together in'intimate surface contact with one another in the stack.
The method of making an electrical condenser stack of non-porous dielectric sheets and metal sheets which consists in cansing the non-porous surfaces of adjacent stack sheets to adhere together temporarily during the stacking operation. by first coating the active non-porous surfaces of individual sheets, prior to stacking them together, with a normally solid dielectric detergent in hot tut) moltei'i condition, and then stacking such sheets together before said coatings on the facing surfaces of pairs of adjacent sheets being stacked together have cooled and solidilied; and, subsequent to such stackin em ploying the detergentlayers to wash out air or moisture from betnveen the stack-sheets, by squeezing the stack-sheets together when the detergent layers are in heated liquid condition thereby forcing out said layers with any entrained air or moisture from between adjacent sheets and causing the non-porous surfaces of adjacentsheets, so freed of air and moisture between them, to be squeezed together in intimate surface contact with one anotherin the stack. s t H I 4.- The method of making an electrical condenser stack of non-porous dielectric sheets and metal sheets which consists in first coatingthe active-nonporous surfaces ofthe sheets, prior to'stacki-ngthem' together, with a normally. solid dielectriodetergent in hot molten condition;- thereafter stacking the sheets together; and, subsequent. to such stacking, employing the detergent layers between the sheets in the stack to wash out air or moisture from between the stack-sheets, by squeezing, the stack-"sheets together when the detergent layers are in heated liquid condition, thereby forcing outsuch layers with any entrained air or moisture from between adjacent sheets,,and causing thenon-porous surfaces of adjacent pairs-ofsheets, so freed of airand moisture between them, to be squeezed together in intimate surface contact with oneanother in the stack. w j V 5. The method of makingan electrical condenser. stack of non-porous dielectric sheets and metal sheets which consists in first coating the active noneporous surfaces of the sheets, prior to stacking them together, with a normally solid dielectric detergent in hot molten condition; thereafter stacking the sheets together; causing the coated sheets to adhere to one another during the stacking operation and preventing unnecessary thickness of detergent layers in the stack, by applying heat to the stack during its building thereby maintaining in liquid condition the detergent layers in-the growing stack, causing excess detergent material to be squeezed out from between lower earlier stacked sheets of the growing stack by the gravity of upper later stacked sheets; and, subsequent to such stacking, employing the detergent layers between the sheets to wash out air or moisture from between the stack-sheets, by squeezing the stack-sheets together when the detergentlayersare in heated liquid condition, thereby forcing out such layers with any entrained air or moisture, from between adjacent sheets and causing thenon-porous surfaces of adj acent pairs of sheets, so freed of air and moisture between them, to be squeezed together in intimate surface contact with one another in the stack.
6. The method of making an electrical condenser stack of nonporous dielectric sheets and metal sheets which consists in first coating the active non-porous surfaces of the sheets, prior to stacking them together, with a normally solid dielectricdetergent in hot molten condition; thereafter stacking the sheets; removing some of the air or moisture entrapped in the layers of detergent between the sheets by subjecting the stack toa s'uflicicntly prolonged bath in-hot molten dielectric material and thereafter squeezing the stack sheets together when the detergent layers are in liquid condition until such layers withany remaining entrained air or moisture have been forced out of the stack and formed ,into' a thin sheath of cooled andsolidified dielec-v tric material around the edges of the sheets and the sides of the stack, said solidified sheath holding the sheets together the stack in intimate surface contact with one anotherafter the removal of thedetergerit layers from between them and after the dis continuance of the squeezing out pressure.
7. The method of making an electrical condenser stack ofnon-porous dielectric sheets and metal sheets which consists in first coating the active non-poroussurfaces of the sheets, prior tostacking them to'gether, with a normally solid diel'ectric detergentin hot molten condition, thereafter stacking the sheets; thereafter washing out air or moisture from between the non-porous stacks of the resulting. stack by squeezing the stack sheets together when the detergent layers are in liquidcondition, thereby forcing out the deter out, with any entrained air or mois: turqfrom between adjacent sheets and causing the non-porous surfaces of adjacentsheets, so freed of air and moisture between them, to be; squeezed into intimate surface contact with one another in the stack; said squeezed out detergent dielectric forming in a thin dielectric sheath around the edges of the sheets and the sides of the stack; and continuing said squeezing operation until said dielectric sheath is solidified by cooling sufliciently to hold the sheets in-their intimate surface contacts independently of such squctming.
8. The method of making an electrical-condenser comprising, a stack of non-porous dielectric sheets and metal sheets enclosed in a casingwhich consists in first coating the active non-porous surfaces of sheets, prior to stacking them together,-with a normally soliddielectric deter ent in hot molten condition; thereafter stac ing the sheets, thereafter Washing out air or moisture from betweenthe non-porous stack sheets by squeezing them together when the detergent layers between them are in liquid condition thereby forcing out said detergent, with any entrained air or ltlt) moisture, from between adjacent sheets and causing the non-porous surfaces thereof, so freed of air and moisture between them to be squeezed into intimate surface contact with one another in the stack; said squeezed-out detergent forming in a thin dielectric sheath around the edges of the sheets and the sides of the stack; continuing said squeezing. until said dielectric sheath has solidified by cooling sufficiently to hold the sheets in their intimate surface contact independently of the squeezing; discontinuing the squeezing; placing the dielectric-sheathed stack in an enclosing casing, spaced from the walls thereof and under high mechanical compression in the casing; softening said-dielectric sheath in the easingby. heating; subjecting the entire assembly while said sheath is soft, to vacuum; and, while continuing the application of the vacuum and the high mechanical compression, pouring hot molten normally solid dielectric as a filler into said space, thereby removing air or moisture from the sheath and maintaining the intimacy'of surface contact of the sheets when the molten filler melts the sheath and until the entire dielectric filler has solidified as an embedment of the stack.
9. The method of making an electrical condenser comprising a stack of non-porous dielectric sheetsand metal sheets enclosed in a casing which consists in first coating the active nonporous surfaces of the sheets, prior to stacking them together, with a normally solid dielectric detergent in hot molten condition; thereafter stacking the sheets; thereafter washing out air or moisture from between the non-porous sheets of the stack by squeezing-the stack sheets together when the detergent layers between them are in liquid condition, thereby forcing out said layers and any entrained air or moisture from between adjacent sheets; continuing such squeezing until the squeezed-out detergent dielectric has cooled and solidified in a sheath around the edges of the sheets and sides of the stack having the ability to hold the sheets in their intimate surface contact caused by the squeezing out of the detergent, air and moisture; discontinuing the squeezing operation when said dielectric sheath has cooled and solidified to hold the sheets in their intimate surface contact; placing the stack in a casing proportioncd relative to the stack to provide a space between stack and easing; pouring hot molten normally solid dielectric into such space thereby melting the dielectric sheath around the stack, while maintaining the stack under high mechanical compression in the casing and thereby maintaining the sheets in their intimate surface contacts after the melting of the dielectric sheath.
10. An electrical condenser comprising a stack of sheets of non-porous dielectric and metal sheets and a casing enclosing such stack and proportioned thereto to provide a space between the sides of the stack and the casing, said space being filled partially with a sheath of normally solid dielectric material around the stack, leaving their surfaces in intimate contact with one another; and said space being further filled with a comparatively thick mass ofnormally Solid dielectric material; said two masses of dielectric material being solidified together and constitutingv a permanent embedment of the stack in the casing; and means holding the stack under high mechanical compression in the casing, thereby maintaining the intimate surface. contact of the stack-sheets during the solidification ofthe entire mass of dielectric in the space between the stack and easing.
'lLThe method of making an electrical condenser stack of nonorous dielectric sheets and metal sheets whic consists in cansing the non-porous surfaces of adjacent stack sheets to adhere together during the stacking operation, by first coating them, prior to stacking, with a dielectric detergent in hot molten condition; thereafter stacking the sheets when the coatings are in adherent condition; subjecting the resulting stack to a bath in hot molten dielectric; washing out air or moisture from between the non-porous stack sheets by ,sequeezing them together when the detergent dielectric layers between the sheets are in liquid condition, the squeezed-out dielectric bein thereby formed ,into a sheath around the e( ges of the sheets and the sides of the stack, which is able to hold the sheets in intimate surface contact after discontinuance of the squeezing operation; discontinuing the squeezing operation; placing the sheathed stack in a casing proportioned to provide a space between the stack and the casing; and pouring hot molten dielectric material into said space, thereby melting said dielectric sheath, while maintaining the stack under high mechanical compression in the casing holding the sheets in intimate surface contactafter melting of the dielectric sheath and during the solidification of the dielectric in said space.
12. The method of making an electrical condenser stack of non-porous dielectric sheets and narrower and longer metal sheets, which consists in first coating the active non-porous surfaces of the sheets, prior to stacking them together, with a dielectric detergent liquid; thereafter stacking the sheets, placing the metal sheets in positions wherein those of opposite polartiy project out from different portions of the stack and elsewhere are spaced inwardly of the edges of the dielectric sheets; mechanically holding the edges of the stacked dielectric sheets to maintain them in common :ilinement in the stack while squeezing all the sheets together, thereby squeezing out the detergent layers and any entrained air or mois ture without disturbing the stacked relation of the sheets to one another by the squeezing operation.
13. The method of making an electrical condenser stack of non-porous dielectric sheets and narrower and longer metal sheets, which consists in first coating the non-porous surfaces of the sheets, prior to stacking them together, with a dielectric detergent liquid; thereafter stacking the sheets, placing the metal sheets in positions wherein those of opposite polarity project from different portions of the stack and elsewhere are spaced inwardly of the edges of the dielectric sheets; n'icchanically holding the edges of the stacked dielectric sheets to maintain them in common alinement in the stack while removing some of the moisture from the detergent layers by submerging the stack in hot molten dielectric material.
14. The method of making an electrical condenser comprising a stack of non-porous dielectric sheets and metal sheets enclosed in a casing proportioned to provide a space between stack and casing, which consists in first coating the active non-porous surfaces of the sheets, prior to stacking them together, with a. dielectric detergent liquid; thereafter stacking the sheets, forming layers of detergent between the sheets; thereafter sqncezing out the detergent layers, when in liquid condition, together with any entrained air or moisture, from between the sheets. permitting the sheets to lie together in intimate contact with one another within the stack; thereafter placing such stack in the casing with its high potential portion near an opening in the casing, the stack being held under high mechanical compression in the casing; and then pouring a hot molten mass of normally solid dielectric material into said space and maintaining a fluid head of said material acting in the vicinity of high potential portion of the stack and the casing opening, to cause holostcric solidification oi the moltcn filler in said vicinity.
15. In the art of making mica condensers, the process consisting in building a condenser stack of sheets which first have been coated with paraifin before stacking; removing some of the moisture from between the sheets and the stack by liquefying the paratlin coatings by immersing the stack in hot molten parafiin squeezing the liquid parafiin and any contained air or moisture from between the sheets of the stack by the application of high mechanical pressure across the stack ends; and cooling the stack while maintaining such squeezing-out pressure, thereby solidifying the paraffin adhering to the sides of the stack on the edges of the sheets.
16. The method of producing mica and foil sheet condensers having clean active surfaces of the sheets, and keeping the same clean, which consists in building a stack of such sheets each first coated with molten parafiin before stacking, and keeping the growing stack warm and the coatings therebysoft during the stacking operation; subjecting such stack, with liquid paraffin layers between the sheets, to high mechanical compression, thereby squeezing out said layers with any entrained air or moisture and causing the sheets to lie in intimate surface contact with one another; placing such stack into a permanent casing and under high mechanical compression therein, with the edges of the stack sheets spaced from the casing; and filling such space with hot molten )araflin.
17. The process of building mica and foil sheet condensers which consists in piling such sheets on top of one another face to face in a stack, dipping each sheetin molten paraffin before pacing it in the stack; utilizing the weight of the upper part of the growing stack to squeeze out some oft-he paraffin from between the sheets of its lower part, by keeping the sheets coatings molten during building by the. application of heat to the stack additional to the heat of the warm coatings of freshly stacked sheets; and finally solidifying the paraflin between and at the edges of the sheets thereby causing the sheets to adhere to one another and permit convenient handling of the stack in further treatment without impairin" its unitary character.
18. he process of buildin a series-sectionat high potential mica and foil sheet condenser which consists in piling such sheets on top of one another face to face in a stack, first dipping each sheet in molten paraffin before placing it in the stack; placing section selparators on top of each section of desired e ectrical capacity; utilizing the weight .of the upper part of the owing stack to squeeze out some of the para n from between the sheets of its lower part by keeping-the sheet coatings molt-on during building, by the application of heat to the stack additional to the heat of the warm coatings of freshly stacked sheets; and finally solidifying the paraffin between and at the edges of the sheets, thereby causing the sheets to adhere to one another and to permit convenient handling of the stack in further treatment without impairing its unitary character.
19. The method of making an electrical condenser stack of non-porous dielectric sheets and metal sheets which consists in first coating the active non-poror surfaces of the sheets. prior to stacking them together, with a normally solid dielectric detergent in hot molten condition; thereafter stacking the sheets; thereafter, when the layers of detergent be tween the stack sheets are cool and solid, ap plying heat to the stack to melt said layers; and, while said layers are molten, employing them to wash out air or moisture from the interior of the stack, by squeezing them out as vehicles for conveyance of entrained air or 'I O l
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2437212A (en) * 1942-12-23 1948-03-02 Frederic D Schottland Electric condenser and method for making the same
US2497066A (en) * 1944-04-14 1950-02-14 Everett D Mccurdy Method of making condensers
US2777976A (en) * 1955-05-24 1957-01-15 Sprague Electric Co High voltage capacitor
US2838797A (en) * 1954-05-06 1958-06-17 Western Electric Co Method of and apparatus for sealing electrical components in a thermoplastic
US2951002A (en) * 1951-09-28 1960-08-30 Bendix Corp Method of making an electrical condenser
US3026457A (en) * 1951-09-28 1962-03-20 Bendix Corp Electrical condenser

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2437212A (en) * 1942-12-23 1948-03-02 Frederic D Schottland Electric condenser and method for making the same
US2497066A (en) * 1944-04-14 1950-02-14 Everett D Mccurdy Method of making condensers
US2951002A (en) * 1951-09-28 1960-08-30 Bendix Corp Method of making an electrical condenser
US3026457A (en) * 1951-09-28 1962-03-20 Bendix Corp Electrical condenser
US2838797A (en) * 1954-05-06 1958-06-17 Western Electric Co Method of and apparatus for sealing electrical components in a thermoplastic
US2777976A (en) * 1955-05-24 1957-01-15 Sprague Electric Co High voltage capacitor

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