US2325718A - Low current igniter - Google Patents

Description

Aug. 3, 1943. TOEPFER 2,325,718

LOW CURRENT IGNITER Filed July 15, 1941 fig. 1. /9

WITNESSES: INVENTOR flc/OdOh f7 Bap/er ATTORNEY 7 6f; the pojol t'o' efiect ignitioni e The apparatus shown in Fig. 1 comprises a V hollowdouble walled-cylindrical shell'5 provided with the usual inlet and .outletttubes, l and}; e through which a cooling'fiuid, such'as'water, is supplied. The shellfi may be composed of a If-the ignitron-is connected to'analternating current sourcejand receives an ignition impulse -.in each alternate half period, as is the usual arrangement, the next ignition impulseoccurs before themercury, returns to its original position and either the mercury is again blown out the ring or the impulse fails even 'to startan arc.

the bottom of In accordance with my invention, I provide an i'gnitron having an ignition electrode whose tip I plurality ofspaced-turns of a wire of a material {which is wetted by the pool. The; distance be: tween the coil and the electrode; and the's'p'acingj. H betweensuccessiveturns oi thcoil is suchjthat' themeni'scus of the mercury between the coil and the electrode is substantially changed by capillary action; As a result ofthe change in .terial such as glass. A cobalt-nickel-iron alloy" 7 sold .underthe trade-name of Kovar may be used 4 i i-o .gis, encircled by a coil. The coilis formed of a:

' to advantage for this purpose. 7 such as Corning G-7 AJ is sealed to thealloy ii; anda cup-shaped shell 2| of the alloy is A ring ii of glass sealed to the upper rim of the glass '59. A rod- 23 eta suitable conducting .material extends a through the center' ofthe cup Zl into the shell 5 and carries at the end within the shell a block v -Zhof thematerial, such as nickel or carbon; which functions as the anode.

l;'end*ofi,tlie'- cylinder 5 adisk ZTis welded to the:

: ie 'erte it is'provided with an'eyelet' 29 of the alloy" through which'a glass exhausting tube 3| is the surface of the mercury, the current required a p ior'ignition' issubstantially smaller thanin the v 1 f absence of the ring; lf'thejmerciiry vapor pressure begins-f to force the'jmer'cury betweenthe coil aridthe electrodeidownw'ard, the space between the turns permits the vapor pressure to 7 clear a pathther'ethrough whereby the cathode spot'rnay escapetofthe space above the surf-ace f'The use of the'coil instead of a solid ring has the'additional advantage of reducing the care i necessaryin positioning the encircling member cwvith' respectto the level oi the "pool, When a 1 solid ring-is usedythe top'of'the ring must be low enough to' permit the ions toescape readily,

" When a coil is used, the'ions'may escape through the first space between tu'rns which is above; the

: mercury.

Although I; prefer to' use a coil, a ring having a plurality of openings therethrough may be employed; -The-size shape, and disposition of the openingsmust be such'thatthe ring may effect asubst'antial 'chang'ein'the meniscus of the-pool 7 whereby the required ignition current issu bstan tially lower than in theabsen'ce of the ring 'lhesnovel features that 'I consider characteristic of my invention' are set forth v'vithp'a'rticu'.

lairity in jthe claims. The invention itseifyhowever," both as to its organization 'and'itsmethocl of operation, together withY'additional objects and advantages thereofgwillbest be understood from the following description of specificembodiments when read in accompanying drawing,j in which:

-Figure' l is :a view in section showing: an ignitron in accordance with the preferred embodimentoi my invention; I Y

FigfiZ' is an enlarged view" of the tip of I the ignition electrode illustrating a preferred em- ,bodiinont of my inventiomf' Fig.3 is an enlargedview'illustrating a modie ficatio 'of my invention; and

Fi 4 is an enlarged View illustrating'a perfo rated ring which may-besubstituted I for the coil suitable etallio 'substancesuch' as steel; Near connection "with the On one side of its center the disk.

sealed. On the other side of the center of the:

disc another alloy eyelet 33 is provided and v j through'it a glass sleeve 35 extends.

thesleeve 35 an alloyrod 31 bent at right angles; at the end within the shell 5 is sealed. At its:

' horizontalendthe" rod 31 is-bent again at-righit an les, and an ignition electrode 39 formedof! a;

rod o'famaterial such as boron carbidecn's'ilijoon carbide, is secured thereto.

' A coil d i formed of "a'pluralityof 'spacedturns j of a wire encircles thetip of the electrode rod;

The wireis m ee r a material which is;

wetted by mercury, such 'as tungsten, molylodenum or other metals havingahigh melting; point. The ends la-and; of the wire extend; on 'eachside of thecoil ll and are secured to a supporting member ll by'a pair. of insulators A96 and The supporting member 'fil in turn, is secured to the r0d3! by a pair of nuts 53Vand55.

/ A-suitable cathode material 51, such -as:mer- V cury, is disposed-on the disk '21 atsuch a height that thecoil ll and the tip of therod 39 extend into it. Satisfactory--operation has been 0btained by employing a coil which-is spaced from theelectrode a distanc'elofthe ordr of ."3=to,3i l

mm., and inrwhich the spacing'b'etween -successive-turns is'of the 'order of .Z-to 1 mm: -'Al-' though I have illustrated thecoil as i for med iof 7 wire having a'circular cross-section, it is'to be understood that a coil formed ofa wire orstrip having a different cross-section may be used.

Hereinafter, the word strip is used to designate a Q 7 suitablelelongated member'such as a wire.

The ex act eifect of the coil! on the meniscus of the-mercury-SI is not knowni The ignition; electrode 38 is of a'material' which is not wetted by inercuryr Thereforegintl'ie absence of the'g coil the mercuryiis depressednear the electrode as-shown by-thedotted-line 58in Fig. 2. Since,

, the coil 4! iswetted bymercury, the surfacelofg' the cathode mercury Eltendsto' ris'eon each side;

of thecoil; .It is my theory that. the. surfacerof the mercury betweenthev coil 4| iandthe electrode, 7 39 assumes the; shape shown by thensolidilinespfil in Fig. ,2; A greater area of thesurface ;of the,'; mercuryjis then located within the boundary regionin whichthe arc discharge takes place, Consequently, a lowercurrentcauses an are disa whi h oduc s h .r u dree o ionization. r

fere nt form which may be used in place :of the 0011,41 in Figs. 11 and 2. Onerof theturnsfiiof' i tlie'electrodekt fand eachf of the remainin'g'turns' hasan" inner diameter greater than the diameter" of the portion ofthe electrode encircled thereby? The tight fitti'ng turn 65 of the coil 83 then-sup I ports 'thecoilin position about the electrode;

sfactol'y operation haslbeen obtained when- Througln Pmqiap r .w h i ici g wneregy:

10f Figs. 1 and 2.

' explainingi my invention; ceftain itheoiieshaye 7' I boundbythese theoii said cathode- Y V a 1 a t i i fi i i fll w ich w e a t ivot n mies e w d-a a2 i -a t can a that aspace'fexists therefiet een which prod s distance such that the surfaceof said cathode body. I a

substanaai -chana at a hodeoitliepooF type anuen iubneieetreo atea ctto thee t a WE by sameatheae ge m i afirade anw ssaeeemhererm dam on me devi'c com rising? a ooltypej' can i 'gnition electrodef -m a contact witliksaid' and a coi mama 1 01 a,; plurality or si ns-maximu irons awdistanee}eritheosae stee -m ni:

e)trie disenarge deviee;compnsm a h incontactiwithfsaifcathode '-said eieetfd em* ag boundary leg s; petweefi sa-ia eiecvmaewaha said J aid aie q charge to 11 in necssitatedby'the'iirior i ana bytnespififi or sure sufficient"to blowtliespot'outfth some" of G the"abrindedclairns j J f f saidcoil c'aii befbuiit upandstill en'able t'h'e "01 1" 111 Aneicthe "dischaijgefdevicje ev c'er chap-ris ng a e A r in Contact withisaidcathode,aiidia mbe 2. In an electric discharge valve of the pool matrial wl' ichds wetted] by said: if type,"andgnition electrode [and a coil; comprising-a p conta with' said ddthddefind a coil, "comprising apiiraiaym dbeniiigsfe t d i umpd 'g -m 5 4g:p 1, circlingsaid{electrodeand nav gone oi'Tm' re ten-being spaeea n dm said I" I saidcath'ode metre ng saidel ng k floi'x'i the inner; a plurality of spaced turns ofa strip of a mateu c 0 its OIItBISIIIfIICG. Said Openings being rial substance which iswettedj by saidfcathodefl 5 1 ape and disposition and said member a encircling said electrode and spaced therefrom in spac j d el ctrodes, distance such a distance such that the ignitioncurrent required 1 that Surface id vfl between i I render said device conductive is substantially member and said electrode is mod fied by cap smallerithan in the absence or said coil. 1 ary a t h b "th -i n nt equired; 4. An electric discharge device comprising a to render said device conductive is substantially a cathode of the pool type, an ignition electrode in 1 contact with said cathode, and a coil, comprissmaller than in the absence of said'lbody.

in: 'a plurality of spaced turnsof a strip of a I athOde 0f t e pbo type. an ign tion electrode v substance which iswetted by said cathode, 'en-n' in contact with saidcathode, saidlele ctrode being circling said electrode and spaced therefrom a'j Y of thetype that produces ignition by reason of between said coil andsaid electrode is modified 1 ar re o tween said electrodeand said ionization caused by an arc discharge 'in the by capillary actionwhereby the ignitionfcurrent" e} and a rin of a aterial which is required to render" said device conductive is sub wetted by Said cathode gnc rc ng said electrode stantially smaller than in thelabsence of saidnjgjand having; a plura lity of openingstextending fromits inner surfaceto tits outersurfacejsaid 5. An electricvdischarge device: mmpnsmg; openings being of a size, shape and disposition-to cathode of the pool type, an ignition electrode 1 permitja cathode spot produced by, saidarc dis:

in contact with said cathode, and aacoiLiormed charge to therethrough before a cathode of a plurality of spacedturns of a stripof a, subfvapor pressure sufiicient to blow the spot but the bottomroi said i s can be builtup, s id o en n s also'beingof such size-shape and disposition and said ring being spaced from said'electrode such a distancethat the ignition current required to rendersaid. device Qonductive is substantially smaller than in e bs n o sa d. em r- 1 H 12., An electric discharge device compris ga cathode of. the pool type,; an ignitionelecti'ode ineontactwiih said cathode, said electrode being of the type that produces ignition by reason oi ionization .,.c,aused ;by an [arc discharge5in the 1 boundary region between said electrode and said ';cathode,, and airing of. a material Which is wetted by; said cathode encirclin saidelectrode and having apluralitygof openings extending fromf its inner surf ace t 0. it outer surface said open- 1 i s e n of asize. ha e a d QS i D tQ p omit some o f the ions producedby said are dise charge to pass therethrough beifcre a cathode .membe An. e i s ha e ev ce c m ri ins a cath ode of thepool type, an ignition electrode in contact with said cathode, saidjelectrode being of thentypel that produces ignition by reason. of

ionization caused by an arc discharge in the .boundaryre gion between said eleotrodeand said I cathode, and a member of a material which is yvetted by said cathode encircling said'electrode and having, a plurality of openings extending from its inner surface to itsbutersurface, said member being spaced from said electrode a distance of the order oi .3 to 3 millimeters; said openings being of' such size, shape and disposi:

, tion to permitsoine oi the ions produced by-said arc discharge to. pass, therethrough beiore said ,arcldischarge can build upa cathode vapor pres} sure sufiicient to blow the arcout the bottom of said encircling member and still enable said mem; .ber to effectfa substantial modification oi the sujijfaoelof said cathode by capillary action, whereby the ignition current required to render the device conductive is substantially smaller I thanlinthe absence oisaid member. H :14, In'cQmbination an ignition electrode for cathode of the pool type, an ignitionelectrode s member encircling said electrode and formed of one ormore openings from its inner surface to a, discharge 'device oi the pool type comprising aired of a substance suitable m'r ignition pur-,

poses, said rod having atip adapted for immer sion in a pe r, and a coil encircling said tip'and formed of aplurality of. spaced turns ofa strip of material which is Wetted by the material of which apool is composed. I v

, 15,111 combination,anignition electrode for ,a dischargedevi'ce of the pool'typecompri'sih'g a I r'o df'ofa substance suitable forfignition purposes and'aboil encirclingsaid" rod 'an'dforme'd of a plurality of spaced turns: of a fstrip which "is wetted by the materialiof which a pool is'com posed, one of, said turnsl fitting' tightly about the end of saidrod and eachof the remaining turns having an-inner diameter greater than the di ameter of thep ortion of the rod encircled thereby, said tightly fitting turn supportingsaid coil in position with the spacebetween'the' rod'and the encircling turns being no greater than 3 millimeters. f ,16. In combination, anignitionelectrode' for a discharg device of the 15001 type comprising. a rod of asubstance suitable for ignition purposes, anda'niember or" a'substancelwhichis vvetted by the material ofWhichfa'pooi iscomhosed, encirclingfsaid' rod and spaced therefrom a distance ofzthe order of 3th 3 millimeters, said member having one or more openings extending from its innerjsurface'to-its outer surface. 7 v

17. An electric discharge'device comprising "a having a tip' immersed in said cathode, and a a material which is vvetted by said cathode with its outer surface, said member having an ,end

portion, with anfirine j' surface fitting tightly about the tip of saidfelectrode Itof'supportthe member thereon'with therer'nain'der. of the inner surface of said member spaced from said electrode T 1' '18.}Anelectric discharge device comprising a cathode of the pool type, anignition rod having an end immersed insaid cathode, and av coil encircling san -0d endand formed of a plurality of .turns of a strip which is Wetted by said cathode, one of; said turns fitting tightly about saidend and supporting the coil position with each of the remaining turns having an inner diameter greater than the diameter of the portionof the rod encircled thereby.

ADOLPI-I Hi TOEPFE

Images