US 2457973 A
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Jam 4, 1949,. I B 2,457,973
IONIZING MEANS AND METHOD 70F IONIZATION Filed Aug. 31, 1945 INVENTOR.
BY mom ATTORN EYS Patented Jan. 4, 1949 UNITED STATE omzmo MEANS AND METHOD or IONIZATION Marietta Blau, New York, N. Y., assignor to InternationaLRare Metals Refinery, Inc., New, York, N. Y., a corporation of New York f Application August 31,1945, Serial No. 613,809.
My invention relates to a new and improved method and to new and improved means for decreasing the breakdown or firing potential which is required to produce an electric discharge or an ionization current.
The invention applies particularly to reducing the breakdown or firing potential which is required in order to pass a spark through the gap between the electrodes of a spark plug. However, the invention is not limited to this purpose.
According to my invention, I locate a cell which produces ionizing material close to the spark gap which is provided between the two firing electrodes of saidspark gap. I also provide a third or auxiliary electrode which is biased to a selected negative potential. This third electrode is insulated from the firing electrodes and it is located close to the spark gap. Some of the material emanated from the cell is collected and concentrated upon this third or auxiliary electrode. In this manner, I can collect upon the negatively charged third electrode, one or more certain ionizing decay products of radium, such as radium A, radium B and radium C, andother members of the series, depending upon the length of time during which the emanations are collected. I can use any radio-active material, which produces ionizing material. The collected ionizing material can include other radium products upto and including radium D. Some of the important active products which I desire to collect are radium A and radium C, which have the most intense alpha ray emission, with consequent intense ionizing action. The ionizing material, which can consist of a single ionizing ingredient or a plurality thereof, is collected sufiiciently close to the air in said gap, to ionize the air in said gap. By thus using said collected active deposit, as radium C, the spark plug will fire, even if its points are fouled.
I thus provide a very active ionizing source which is useful whenever it is desired to lower the discharge potential through any ionizable atmosphere, irrespective of the pressure of said ionizable atmosphere.
Other objects of my invention will be stated in the annexed description and drawing, which illustratesa preferred embodiment thereof.
6 Claims. (01. 315- 111) 2 grounded. The auxiliary firing electrode 2 is also grounded. By inducing alternating current at suitable high voltage in the coil S, the spark is produced between the firing electrodes I and2, in the usual manner. These firing electrodes I and 2 are made of any suitable metal or alloy. Other well-known details of the spark plug and of the ignition system are not illustrated, since thesame are well-known per se. The firing electrode l extends through and it is fixed to the insulating core 4 of the spark plug to the metal cap I, and the firing electrode 2 is connected in the usual manner to a metal shell which isfixed to said core 4.
The third or auxiliary electrode 3 is madeof any suitable metal or alloy, such as nickel. It need not be made of radio-active material. This auxiliary electrode 3 also extends through and it is fixed to said insulating core 4. One end of this auxiliary electrode 3 is connected to the negative terminal of a, source of biasing potentiahwhich is represented by the battery B. The positive terminal of the battery B is grounded through wire 8 and through a variable resistor R. The circuit between the positive terminal of battery B and the ground may include a variable inductor as well as a variable resistor.
The invention is not limited to any specific example which is stated herein. However, in order to provide certain practical working information, it is noted that the negative biasing potential whichis impressed upon the auxiliary terminal 3 can be between voltsvolts, in the case of an ordinary spark plug. The electrode 3 is not grounded, save through the bat tery B.
A radium cell C is supported in close proximity to the firing electrodes l and 2, and also in close proximity to theauxiliary electrode 3. As an example, the distance between the cell C and the tip of the auxiliary electrode 3, can be from. 1 mm. to 2 mm.
In this embodiment, the cell C is shown as being embedded in and fixed to the insulating core 4 of the spark plug. The radium cell C can be of any type. As an example, the cell C may be of the porcelain type, and it may have a filling of Hahn mixture.
This Hahn mixture is a well known mixture of radium or radium salt, with iron oxide. Since this mixture is well known per se, further description thereof is not required. especially as the invention is not limited to any particular type of radiation cell. Such cell is permeable to the radon which is produced in said cell, it itcontains radium or a radium compound.
gap which is located between thetipsof electrodes.
I and 2. The diameter of the auxiliary electrode 3 may be from 2-4 mm. The fimportant de'cay products from the cell C will be collected "iupon the entire adjacent and exposed part of theauxiliary electrode 3. That is, if radium is .used in cell C, gaseous radon is emittedirom the cell "C,
and this radon disintegrates to produce the well known decay products radium A, B and C, and such :decay .products are collected upon the-exposed part of the auxiliary electrode 3. The
radium A and C which .are thus collected, emit I alpha rays. Optionally, the 'tip :of the auxiliary "electrode '3:may be very close to the cell C, so that there will be a maximum concentration-of the decay products upon the .tip of the auxiliary electrode 3.
I thus produce a novel and powerfulsource of ionization in very-close proximity :to the .spark gap which is locatedxbetween thetips of the firing electrodes 1 and -2. Without the auxiliary Telectrode 3, thereiis no 'such collection and concen tration of the decay products, so that the desired efiect is notproduced to any substantial extent.
By using a sufficiently intense or powerful @cell C,:I canreduce the ordinary required firing potential between the firing electrodes :1 and 2 muchas 20%;
When the internal combustion engine is-idle, there will =be a steady accumulation of the decay product orproduots upon the auxiliary electrode '3. Hence, when the engine is started, the auxiliary electrode '3 willhave its maximum'effecn just by :as
at the time when it is required .toproducequick and easy starting.
The invention is also useful in securing ,proper firing of fouled spark plugs. If 'dust or carbon collects upon the auxiliary electrode 3, thisad'oes not interfere with the proper working thereof.
As an example, the cell C may contain 120-5'0 micrograms of radium or a mass of aradiumwsalt which comprises .20-50 micrograms-of radium.
Theelectrode 2 isconnectedinthe usual :man-
ner to the 'metalshell of thersparkiplug, and :said
metal shell is grounded in the usual manner.
When the spark-producing current is: an alternating current, the central electrode l, which passes throughthe'insulating core 4, is alternately plus and minus relative to the grounded .main electrode ;2, and the grounded auxiliary electrode 3.
Hence, when electrode 1- is positive during a respective firing yperiod, *a branch "spark =may' be produced between electrodes 1 and and i8. branch current willbe sent throughwirefl, in the direction of'arrow'e. In suchcase, the potential difference between electrodes land 6 "is in series with the potential of batteryB, :and they are cumulative.
When electrode lisnegative relative 1to;ground ed electrodes'Z and 3 during thenext firing :period, the potential dilTerence between electrodes] and :3 is opposed tothe potential of batterykB. alliepending =upon therelation between the-difference zeroo'r'substantially zero, although the invention "is not limited to this feature. ui the :negativelyblased collector electrode 3 from I can thus shield the discharge current. The branch circuit of wire may have'considerable resistance or in- 1ductanceor-both in order to minimize the branch current, to substantially zero. In addition or as an alternative, the space between the tips of electrodes I and 3, may exceed the space between the itipSiOf electrodes l and ,2, thus -minimizing a branch :spark between electrodes i and .3, "or ;preventingzthe formation of such branchspark.
By preventing the formation :of- 3,.bIQII1Ch'2SDE1k and branch current the electrode :3 is subjected to a constant negative potential him :by the battery B. ,If there is a branch spark with the-re- ."sultant branchcurrent, the bias of auxiliary-electrode 3'Iwil1 vary' while the engine iswoperating.
The ignition: system m'ay :be of any type. For example, thefiring current may be supplied by a magneto.
The :ion'izabl'e gaseous filling of the space Thei-tween the electrodes I, "Z, and 3 may be air, "or .anyJgas or mixture ofgasesyora-vapor, orfa1mixtureof a vapor with-a :ga's'or gases.
The discharge :device may have a pair-ofzdischarge "electrodes, 'or any greater number-of :discharge :electrodes.
' The inegativepotential biasirnay Ebe impressed upon auxiliary electrode 3 "by any means, zand'ithe invention is not .limited "to a :source of :unidire'c- .t'ionaland constant :potential, arrditdsznotdimited "to impressing :a -;continuous :or constant .n'cgative potential upon electrode 93..
I have described ta preferred embodiment of my invention, :butnum'erous changes and -3omis sinus and additions can "beimade without 'rdepartingifromritsiscope. i I
Iiclaimiz 1. A spark plug which has an insulating -tcore .and a pairofifiring electrodeswhich-are separated by r sspark gap, aradium :cell .ifixed to said core, said cellr;producing a gaseous .d'ecay product :of radium:which disintegrat'es ito iproducesuccessive ionizing decay products which include radium FA, :radiumlB, and radium C, said-cell:being permeable to said gas'eous decay :.product,- a conducti-ve collectorcfixedlto said core, means foriimpressing:a suflicient negative potential on said collector "to collect ionizing decay products zresulting :from the disintegration of said gaseous :decayiproduct upon thexsurface of said collectorpsaid Icolleotor being sufficlently-close to said sparki'gapitoionize the medium therein by means .ofzsaidzcoll'ected ionizingzdecayproducts.
2. :An :ionization discharge device said device comprising discharge electrodes which'areispaced by a .discharge. gap and :which areflocated in a mediumiwhich is selected from a class which is selected from. gases and vapors, saidimedium being underisufiicientpressure to providean ionizaition discharge :through saidinedium in said discharge. gapwhen. firing potential 'is:'applied to said discharge electrodes, a conductive :collector held in fixed relation relative to said discharge electrodes, a radium cell which is supported in fixed relation to said discharge electrodes and collector, said radium cell producing a gaseous decay product of radium which disintegrates to produce successive ionizing decay products which include radium A, radium B, and radium C, said cell being permeable to said gaseous decay product, means for impressing a sufiicient negative potential on said collector to collect ionizing decay products resulting from the disintegration of said gaseous decay product upon the collecting surface of said collecting electrode, said collecting surface being sufliciently close to said discharge gap to ionize the medium therein by means of said collected ionizing decay products.
3. A method of producing an ionization discharge through an ionizable medium in a discharge gap between discharge electrodes, said ionizable material being selected from a class which consists of gases and vapors and being under suiiicient pressure to produce an ionization discharge when firing potential is applied to said discharge electrodes, which consists in disintegrating radium to produce radon adjacent a conductive collector, subjecting said collector to a sufficient applied negative bias to collect ionizing decay products of said radon on the surface of said collector, and subjecting said medium in said discharge gap to the ionizing action of said collected ionizing decay products.
4. In combination with a spark plug which has an insulating core, and which also has a grounded firing electrode and an ungrounded firing electrode, which are separated by a spark gap, and which also has an ignition coil which has one end grounded and the other end connected to said underground firing electrode, a radium cell fixed to said core, said cell producing a gaseous decay product which disintegrates to produce successive ionizing decay products which include radium A, radium B, and radium C, said cell being permeable to said gaseous decay product, a conductive collector fixed to said core, a source of unidirectional biasing current, the negative terminal of said source being connected to said collector, the positive terminal of said source being grounded, said source being of sufiicient voltage to impress a sufficient negative potential on said collector to collect ionizing decay products resulting from the disintegration of said gaseous decay product upon the surface of said collector, said collector being sufiiciently close to said spark gap to ionize the medium therein by means of said collected ionizing decay products.
5. A combination according to claim 4, in which the circuit of said source has sufiicient impedance to substantially prevent any branch spark between said ungrounded electrode and said collector when a spark is produced in said spark gap by said ignition coil.
6. A combination according to claim 4, in which the space between the tip of said ungrounded electrode and the tip of said collector is sufficiently great to substantially prevent any branch spark between said ungrounded electrode and said collector when a spark is produced in said spark gap by said ignition coil.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,871,279 Rentschler Aug. 9, 1932 2,022,140 Michel Nov. 26, 1935 2,032,545 McElrath Mar. 3, 1936 2,128,457 Fairchild Aug. 30, 1938 2,254,169 Dillon Aug. 26, 1941