US2521714A - Filament support structure - Google Patents

Description

F. D.. GOODCHILD FILAMENT SUPPORT vSTRUCTURE Sept. l2, 1950 Filed Nov. 29, `A1.7947

ATTO

Patented Sept. 12, 195()` :ru-,amour surronfns'raucroer signor to International Standard 'ElectricGorporation, New York, N.1Y.,ay corporation fof "Delaware jf Application .November 29, 1,941.7, Np..-

In Greatritain October' lt, 1346;@

' Section 1, Public' Law yAugustS, 19M

HPatr-:nt expires Uctoherilgi--l ancianas. (ci. 25m-27.5,)

"The present invention relates to supporting means for nlaments which are adaptedio be heated by means of electric current passed therefthrough and is directed towards means for preventing distortion of vthe filament. orl filaments carried` by the said supportingrneans due to unequal thermal, expansion-of Dartslthereoi. lIn

particular the invention is concerned with supporting means which comprise. rodsy which sup*- port the rfilament wire or Wires and which are o f unequal length. i

Heating' filaments and :the supportingmeans therefor are used to a large extent inelectricy lamps and in electron discharge devices. fIn many of these, ltheiilanflents are carried. by means oftrods which, also supply. the heating current. According tc the general: oonstructional iorrnk of the device ofywhich. the mament and its supports form a part, these rods maynot all, be of the same length with the consequence that there is aiterldency' for 'them to be subject todifierent It'hermal elongations WithA lconsequent distortion of the filamentl Wires. It is usually. easierto, compensate' for equal thermaldistortions thanjkfor unequal expansions. or` contractions atjthe filament. ends f 'the' rods. .AltlrioughV here and carryingy supporting rodsjicr one set ornament wires',`a` thin lmetallcdisc attached to said' outer tube near its junction withY said vitreous member throughout theV` description whichuiollows attenl tion will be directedtowards the case, of a fllament structure for an 'electron dischargedevice, the present invention is not limited inits `application to-such devices.

"The present invention consists in a .supporting meansA for filament or filaments adapted to`A be heated by means of electric current passed there- `through and comprisingtiilament supporting rods of unequal length in which said rodsr are secured torigid transverse members'atvsubstantially equil distant distances from; their filament ends and are supported atithe' ends remote ,from they lamenttbinmeans, flexiblyv positioningsaid vrods of unequal length in relation to each other, said rigid transversemembers beinghlocked together to prevent differential thermal extension of said rods with `respect to lonel another atvtheirr` filament ends.

As applied-:to a'particiular embodiment to be described the invention provides a lamentsup- .porting means for a high power .electron-,discharge .device .comprising a pair of Atubes oi conducting Imaterial, one concentrically within thefothels for supplying v.current to said. ,iIam-ent, said... tubes beinghermetically sealeditoeither. end of abarrel t shaped member of vitreousmaterial which sur- :rou-nds said; inner tube and forms a continuation of said outer tube, a first platform of conducting material mounted-upon said inner tube at right angleslthereto and at .ftheend thereof whichf-is tial th'ermal expansion' of saidfrods is prohibitedl -on thel'rfilament sideov said platforms and may be takenfup at the other` ends ofthe sets ci rods byvirtue fof'v thefffiex-ibilityj ofY said thin i metallic vdisc.

lTheinventioirwill now bedescribed by way of example'in a particular` embodiment for ahigh .power-electron discharge device as illustrated in the: accompanyingdrawing invvhichFigj lA is a 'sketch ofthe filament support and'Fig'. 2 a sketch foffadetailthe'reof.' A

lili'gs l@ of fthe' drawing'. l'fu'rstrates alainent supporting'v structurewhich is carried in an lectron *discharge i device' byf-'means securing the'fl outer tube i oa pair of concentric tubularcurrent K4conductors to the' envelope lofv the device. vThe r`tube: l isfprovidedfat itslower end with av ared A;cone"'2*to which is sealed a barrel shaped mem'- .berf 3 of glass@ orf similar vitreous material; "The inner tubularconductor1` 5' is similarly sealedv 'to the-othxer end-ot memberi3 at 5r-`and carriesva platform 6 upon a member closing the "end ofthe tube t. This general form' ofconstructionis descri-bedr4 more fully andfisl claimed i in U; Si Patent -'Non2-,4(i5;359, issued" March' 29;:1'949yt0 T. Gibson0 entitled Current lead-inseal' for electric :vacuum-'tubes andilthe like. *The platform 6,- Y which is ofcoppernhasxbrazed?to "its corners n ccnpersupportfrods g1; Attire; upper end ontnem- 'ben t. a thinciilulardiscf, 8:- of copperzis braze'd'fto the outer tube l and carriesthree copper rodsr i secured thereto by adjusting col-lansffland. nuts luf on theundersideof disc. E'Ihe-{rodsfl-H and 9 t lie.: atythe corners of`v aregularfhexagon centered ,on and. at .right angles Ito the aX-isofthestructure. rods haver extensions 1- and 9.5 respectively. Tlieseiextension r pieces, a'reV v ofs molybdenum f and dit i into irecesses inthe ends l o f-,Yi'the' copperercds url'ierefftheyare :heldbymeansnfy grub screws/fl l. nodsj l4 and-1@'passf-thrcughfholes inffthe .ccrnerso theirespectivefplatforms Yl-and "lf3, which# are of niokeLl and-to `which` the `rodsare bra-Zed. v- Theirodsl hand 9! vcontinue f upfintortlfie @tubular anode l-(not shown) of ;the' dischangevdeyvice and terminate .on further plat-formsfl; and -`i5;:respectively. A number ors. filament anchors I 6 and I 1 yfit onto the respective platforms I4 and I 5. In the embodiment illustrated there are nine such anchors attached to each platform. An,-

chors I6 are longer than anchors I'I so that the tops of both sets are at the same height'along" the axis of the assembly. Filment `wires IQ are Y welded to the anchors I6, II attheir *upper ends N n.partbeing of copper and the other of molyband to molybdenum angle. shaped members I9" at their lower ends. Members I 9 are secured together to form a spectron, held by center piece which has a sliding fit into a collar which may be xed to another part of the discharge device,

such as by insulating means to grid support 'rods which are not shown. In operation the discharge device is mounted vertically so that the filament wires are held in tension under gravity, equal changes in length being permitted by center piece MZIJWsliding, axially within its-supporting collar. .Providedthe expansion for eachl,of the4 s ets of .rods and wires are the same, thermal movement isl thusv taken up. The rods 'I and 9, however are not of the same length and a diffculty ispresented, particularly if say, some eighteen kilowatts -fof power are to be dissipated by the filament-,and hence the supporting rods are also correspondingly heated.- In, order to overcome this ydifficulty we lock together the twov platforms and bolt 22.l Furthermore the platforms I2 and ,I3 Vare equidistant from the lower ends of their -respectivemolybdenum rods.- AHence all the parts below-platforms ;I2 and I3are constrained to move together, while the resilience ofthe thin copper disc 8 takes up the differential extension ofthe -rods with respect to rods 'I.- In order to provide .greater iiexibilitythe disc 8 may be slotted as smhown.. '.'lhe'method of ylocking theplatforms .26 and v21 are welded to boltV 22 as shown ati28 and 29. l

j'It will be appreciatedthat in this embodiment 'the platforms I2 and I3 are provided and locked together rather than locking together lplatforms I 4 and I5 as the latter are in a region of excessively high temperature during operation of the device. At the temperatures likely to obtain in this region ceramic` insulating material Afor the locking means could be used.

Although the above description has been relatedto a particular embodiment of the invention -inan electron discharge device, it will be apparent that, as stated previously, the invention may `be applied with advantage to any filament 'sup-l porting structure wherever filament wires adaptedto be heated by electric current, are supported by rods of unequal length.

What is claimed is:

f 1. Filament support structure comprising a 'r'strigid transverse member, a, rst set of lament supporting rods of a given length each Asecured ata given distance from its filament end to saidl 'first rigid transverse member, a

second rigid transverse member locked to said first rigid transverse member and insulated therefrom, a second 'set of filament supporting rods of greater length than said given length and each secured at substantially said given distance from its filament end to said second rigid transverse member, and means adjunct said 'rst and second setsl of rods adjacent the ends remote from the filament endsffiexibly posidenum, the molybdenum part being attached t0 said filament.

3. Filament supporting means according to claim 2 in which said molybdenum parts of said rods are of substantially equal length.

4. Filament supporting means for a high power electron discharge device comprising a pair of concentric tubes of conducting material for supplying current to a filament, a member of vitreous material hermetically sealed between said concentric tubes,`a first platform of conducting material mounted upon said inner y tube at right angles thereto and adjacent the portion of saidinner tube sealed to said vitreous member, 'a` first set of filament, supporting rods mountedv on said first platform,` a thin metallic disc' attached` to said outer tube near, its junction with said vitreous member, a second setfof relatively Alonger I filament supporting, rods mounted on said disc to compensate for relativevexpansionV ,ofsaid set of longer` rods, a second 'platform secured to said rstr set of, rods atl a given distance I.from thelament ends of said first set of rods, and a thirdh platform secured to said second set of rods atsaid given distance from the filamentenfds` of said second 'set of rods, said second and third platforms being rigidly secured together yto'prevent differ-- ential thermal, expansion between the filament ends ofsaid first and' second sets.` of rods.

.5.'Filarnent supporting means according to claim 4, in which said supporting rods of unequal Ilength are Ieach in vtwo parts, secured together, the one" part being o f copper andtheother. of molybdenum, l each of 4 said molybdenumparts being of substantiallylequal 1ength,.one endof the' molybdenum part attached to saidl filament, said first, and second platformssecuredto," the molybdenum parts of. the respective of 'said rods ata point intermediatethe en ds thereof, Filament ksupporting means according to claim 4 in which said first and second platforms aresecured together by'means'jof insulating rcollars bolted together. n

7 .Filament supporting Imeans according to claim 4 in which there are six` rods, three to each set, arranged: hexagonally. y

8. Filament supporting means according yto c1aim-4 in which, there areprovided two further platforms, one to each s et of rods, secured theretoadi'acent the filament ends thereof. FRANK DOUGLAS GOODCHILD.

REFERENCES VCITED The following references are of recordin the file of this patent:

UNITED STATES PATENTS l Number Name l Date 1,965,338 Gibson et a1.` July 3, 1934 V2,226,680.71, Wheller et al.` Dec. 3l, 1940 2,317,222 `Ronci Apr. 20, 1943 2,398,608 Werner et al. v- Apr. 16, 1946 2,399,004 Crawford Apr. 23, 1946 kk2,404,042 Dailey etal. -1711 July 16,` 1946 2,419,124 Dailey Apr.'15, A1947 FOREIGN PATENTS 'Number 'Country Date

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