US2029570A - Spark plug - Google Patents

Description

LHIYIINI URUQO Lf LDLHUI'- SPARK PLUG Uriginal Filed Dec. 3U, 1932 R. Y. ,mn u mm 'Vil T A, T 'a A w KY., A. m ff@ A Patented Feb. 4, 1936 A PLUG Armen A. man. )am m El.

-ApplicationIieeenilaer 8l.

Renewed 1982, dal No. 3,455

In: 1. nomma (cru-eil /J *Jrg This invention relates to spark plugs and is directed more particularly tothe provisions of .podtive means for the elimination of detrimental inductance and the transformation of the en g ergy thus usuallywastedintoashower of capacity discharges.

In a conventional type of spark plug, after the initial capacity discharge, the spark gap becomes ionized and loses a greate;l portion of its resist- 1o ance and in consequence a low voltage arc is established across the gap. This arc continues until all the energy of the spark is spent. 'I'he ignition of a charge in the automotive engine depends almost entirely umn the capacity component of the discharge across the gap and if this component lfails to ignite the charge the inductance component is much too low a voltage to cause such ignition. As a matter of fact, the inductance component is not only of negligible zo consequencegso far as ignition is concerned, but is detrimental in thatitproduces a considerable amount of heat. It lowers the =resistance to erosion of the material used as distributor points and electrodes, and under severe conditions may cause the electrodes to become so highly heated that they remain incandescent and cause preignition. 'nre object of the present invention is primarily the conversion of the inductance component of the spark into a series of high voltage capacity discharges. 'I'his is accomplished by the introduction of a series of minute air gaps in the spark circuit, herein termed the transformer. 'I'he resistance of the transformer requires higher voltage than the ionized spark gap would require.

Therefore, as soon as the induction arc is established, the circuit is cut off by the transformer. During this no-spark (infinitesimal time) period.

the ionization of the spark plug gap is lost, and

4o the voltage in the spark circuit has to rise again to a value necessary to re-ionize the gap. This cycle vof operation is continued until all the energy of the spark generator for that period is spent.

The result is a shower of high voltage capacity 45 dischargesinsteadofasmallcapacity discharge and a large inductance arc.

It has been heretofore suggested to incorporate in an ignition 'circuit a so-called transformer or transformer element. for the purpose of utilizing -50 the desirable and essential characteristics of the capacity component, and to eliminate the undesirable qualities of the inductive or heat oomponent. These prior suggestions, however, have invariably depended upon the employment of a 55 laminated structure composed of alternate plies or laminatiom of conductive and di-electric ma terial arranged in the form. of superimposed washers after'the manner of a condenser. These prior devices have depended for their operation upontheionisationofairinthegapsbetween g the successive spaced apart conductive washers. and experience with these types of devices has conclusively shown that they are inemclent, unreliable and susceptible to wide variations in operation. In other words, these devices'operate 10 in an atmosphere of air and air mustbe present in order to provide for the ionization which is essential to their operation. Continued oxidation of the parts accordingly takes place and pitting or erosion prevailsto amarked degree. 'u

It is the purpose of this invention, among other objects, to provide means which will be uniform and unchanging in its operation for long periods, means which will not require the presence of air for its eiiicient operation. and means which is, as 20 a matter of fact, hermetically sealed in an airtight compartment to insure its uniform, constant and unfallingjpperatlon.

In one of its preferred practical forms, the invention consists in incorporating in the ignition 2s circuit a body of pulverulent or granular material which material consists of a combination of conductive and non-conductive substances admixed with' one another, so that the granules or particles pf the one substance are separated or spaced so by the granules or particles of the other substance. This body of pulverulent or granular material, packed under pressure in a hermetically sealed chamber. is incorporated or included in the ignition circuit and may conveniently be in- 35v corporated within a chamber-formed in the plug by packing the material'under pressure within such chamber or by enclosing it within a cartridge contained within the chamber. The particular materials which I -prefer to use in the 40 manner of their employment will be hereinafter more fully explained. i

A further object of the invention is to increase the power factor, and therefore the power available in the ignition circuit through the introduction of an ohmic resistance. When the pul- 'veruient material is packed in the chamber, as

stated, thereisbound tobeacertainamountof entrained air. 'Ihis air constitutes. initially, a variable resistance. After the initial operation of the circuit. this air becomes ionized and becomes negligible and as the chamber is sealed, it is thereafter constant in character. 'Ihe metallic parti-` cle of the mixture are4 slightly oxidized during this ionization of the air and thereby attain a 6d sfr" 2 aasvo constant and unchanging state having a slightly higher resistance than the metal itself. The resultant material does not change. Through the use of the material in its constant operating form.

5 the power factor is increased according to the formula expressed as follows:-

Ps-:EI O

where Pzpower Y 1 n=v01tsze -I=current =the angle of phase difference cos e=power factor Exhaustlve experiments have shown that certain requisites are essential to highest enlciency. E. g., the condenser chamber should be absolutely ain-tight. T'his essential for the reason that the process of oxidation should be limited to a value desired. Otherwise, the voltage of the spark generator may rise to a higher value than that for which it is designed. For this reason, double sealing is resorted to. 'Die powder mixture is preferably nrst sealed in a cartridge before placing it in the transformer chamber and the chamber is thereafter sealed. 'lhe cross sectional area of the condenser should be of a magnitude so that the current density will not raise the temperature of the metallic parts to a value close to its fusion temperature. The percentage of conducting material to the insulating material and the pressure put on the mixture should be limited to a value so that the aggregate sum of the air gaps will not be any more than .010 inch. The best results are obtained within the range of .006 to .009 inch. The specic gravity of the insulating material and the conducting material should be as close to each other as possible, so

that (under the engine vibration) the possibility of separation of conducting particlesfrom in- .iisulating particles be eliminated. A variation of 5% in the speclnc gravity of the two materials has proven tobe permissible, by actual test, but a greater difference cannot be depended upon.

' 55 Features of the invention, other than those specified, will be apparent from the hereinafter detailed description and claims when read in con- `iunctiorri with the accompanying drawing.

The accompanying drawing illustrates different practical embodiments of the invention, but

the constructions therein shown are to be understood as illustrative, only, and not as defining the limits of the invention. v

Figure l shows the preferred form of spark 5 plug'embodying this invention, the plug being shown in central vertical section.

FigureZ isafragmentalsectionofapliig showing a modified doubled seal form of the invention.

Figure 3 is a central section through a cartridge embodying the construction of Figure 2.

.'Ihe plug shown in Figures l and 2 embodies an insulating element i which may be conveniently of porcelain. This insulating element is 1s mounted witliinaznetallicshelllinwl'iichitisl conventionaliambnutt. Mathe dedelectrodeoftheignition circuit orinsulatedelectrode. Inthe showingofl'ig.l.theporcelainismadecfsub stantiallythesamesineandshapeasisconven- 5 tionallythecase. uttheupperportionishol- 15 ce. the screw I, with copper gasket Il, into a suitable ceramic cement. i. e., drous cement, prior to being screwed into plaoeduringtheassemblyoftheplugpartsand theshank Ilofthebindingpostissimilarlygo dipped into In the form of the invention shown in Pig. i, the pulverulent or granular material to which I havereferredismerelypacked intothischam ber, so as to entirely fill the chamber between the screw! andtheshankll. Whentheshankgo Il is screwed into the plug. it applies pressure to and packs this material tightly and precludes the material from jarring about, so that in eifect the material constitutes a tightly packed mass. `In'thestructureofl"igure3,thematerialis 35 contained within a cartridge comprising a cylindrical body Il of insulating material such for example as mica.- 'nie ends of the body are closed by metal caps l2 and the said material is contained l'within the resulting enclosure. The 45 cartridge is either hermetically sealed in any suitable way as by a peripheral coating of ceramic material Il, as shown in Figure 3, or left unsealed andplacedin asealedplugchamber as shown inll'igure2,sothatthebottomcap I2 of thecar 45 tridge seats on the head' of the screw l, while electrical current is adapted to be carried from the shank Il to the upper cap I2 of the cartridge through a small compression spring Il. The chamber may be hermetically sealed through the 56 use of ceramic cement or in any other suitable way as hereinbefore stated.

Two examples of the manner in which the material may be incorporated in the ignition circuit have been given. but I wish it understood that 55 the invention is not limited to these specific features and that said material may be incorporated in the ignition circuit in other ways without defrom the invention.

The material to which I have referred is desigso nated generally in the drawing by the reference character I4. As herelnbefore stated, this maferial may be either granular or pulverulent or a. combination thereof and I am aware that a wide variety ot substances may be employed in this 05 connection. For the purpose of illustration. however, and by way of example, I have found that the conductive material employed may be granulated or powdered duraluminum. This material has c nigh melting point and is not readily 7 oxidized. The conductive material employed should have a relatively high melting point. should be a material which does not readily oxidizeandonewhoseoxide doesncthavearesistu' UKUbb mar tumor.

acaasvo ance which materially varies from the resistance of the metal itself.

The non-conductive material should be a materialwhichwillnotreadilyoxidisaamaterial which is a good non-conductor, one which has substantially constant characteristics and which will not deteriorate over long periods. It is possibleandinlomecasesmaybedesirableto employ a mixture of different metals or conductive materials and a mixture of a plurality of nonconductive materials. However, by way of example and for the purpose of illustration, I may state that I have found a mixture of powdered duraluminum and powde ca gm with structures embodying the presont invention. as hu'einbefore described, has conclusively demonstrated the high eiiiciency for the purposesstated. Theharmfuleffccts oftheinductance component in the ignition circuit is eliminatedoratleastreducedtosuchsmallproportions that it is a negligible quantity. while the capacity component is enhanced to an astonishins decree- An important practical advantage of the pres ent invention resides in its manufacturing econon ,w en esepow ces mies,asthepresentinventionmaybeincorporat iowuered'r crsiearrrm aire nixeil, ed in plus structure without appreciable aamltlilnmlubtsn'llllmmmn. It is #10ml esential to have the substances which enter into Furthermore. the plug when completely fabrithis mixture of substantially the same or relacated has been found to function emciently over tively close speciilc gravity, so that they will not protracted periods without any apparent loss or tend to separate or stratify under vibration. If drop in emciency and a noticeable lengthening these specific gravities are widely divergent. say of the life of the electrodes has been noted as more than 5%, the heavier will tend to settle to evidenced by the relatively slow erosive effects the bottom. while the lighter will be displaced which generally result from overheating. and rise to the top of the mass, whereas accord- The foregoing detailed description sets forth ing to the present invention, it is necessary for Y the invention in its preferred practical form, but maximum eillciency that the admixture of the the invention is to be understood as fully comparticles or granules be such that said mixture is mensurate with the appended claims. substantially uniform throughout and that the I am aware that aside from the means which particles of the conductive material be substan- Iv have described the present invention includes tially uniformly spaced in relatively close spaced a novel method which also forms part of this vinrelation with interposed particles of non-conducvention. tive material serving the spacing function. While Having thus fully described the invention. what I have referred to mica and duraluminum I claim as new and desire to secure by Letters productive of satisfactory practicfreslits, I am tent is: aware that other substances may be used without l. In an assembly of the character described, departing from this invention. .ChmmiLnl for an ignition circuit including a body of matter example, has given a very satisfactory performcomprising a mixture of finely divided conducance when a ixed with For these reative and non-conductive materials interspersed sons, and without a mpfing here to specify all with respect to one another in the body, said the dierent conductive materials and all the conductive and non-conductive materials being different granular materials that may be emof substantially the same speciiic gravity. ployed, I wish it understood that the examples 2. In an assembly of the character described, given are illustrative of equivalent materials that an ignition circuit including a body of matter may be used in the carrying out of this invention. comprising a mixture of finely divided conduc- In the foregoing detailed description. I have tive and non-conductive materials interspersed referred to a mixture of powdered duraluminum with respect to one another in the body, a herand powdered mica as giving very good results metically sealed walled chamber enclosing said and have stated that where they are tov be assobody of matter, said body being firmly packed ciated as specified, the conductive and di-electric pulverulent materials should be of substantially non-conductive materials being of substantially the same or very close to the same specic gravthe same specific gravity. ity so as to preclude separation or stratification 3. A spark plug provided therein with a herunder vibration. I have further found, that the metically sealed chamber, a conductive member present invention also consists in adding to these extending from said chamber to the ignition gap materials, if desired, a suitable binder which will of the plug, a second conductive member also form these materials into a composite homogeleading from said chamber and adapted for elecnous mass. This binder must be of a material trical connection with an ignition-lead, the adwhich will not break down or disintegrate unjacent ends of said members being spaced apart der the electrical discharge which must necesat the chamber, and a bodv of matter enclosed sarily pass therethrough. For example, I have within the' chamber and embodying a mixture found that the granulated or pulverulent mateof conductive and non-conductive materials of rial specified maybe mbe substantially the same specific gravity in pulgim, cement, plaster o1' paris or t@ like with an verulent or granular form with the particles of within said chamber, and theconductive and v ma van Wmmm.

anhydrous liquid which acts as a bingenang said materials interspersed with respect to oneic.

forms the element into a. suaily-Eonolithic another, said body being packed within the form. This binder holds the particles together, chamber to have electrical contact with said precludes relative movement of the particles and conductive members.

provides a constant or uniform path for the cur- 4. In an assembly of the character described. rent which path is unchangeable in its characa spark plug provided therein with a walled ter. When an appropriate binder is employed as chamber, a conducting member leading from the stated. it is not essential that the di-electric and chamber to the ignition gap of the plug, a second conductive materials be of substantially the same conducting member leading from the chamber specific gravity because when embedded, inabindand adapted for connection with an ignition lead,

eras stated, they cannot move or stratify. Consesaid conducting members being spaced apart at 75 is i.

the chamber. a hermeticaliy sealed cartridge within-said chamber,saidcartrldge having conducting terminals and a non-conductive intermediatewalhtheterminalsoithecartridgebeingeiectricallyconnectedwiththesaidrespecdve eonductingmemberaandabodyotmatterhermetically sealed within said cartridge and in contact with the terminals thereof. said body ci matter comprising a mixture ot pulverulent or granulated conductive and non-conductive materiaiatheparticlesoiwhichareinterspersed withrespecttooneanother.

5.In an assemblyoithecharacterdeserihed,

'.gsparkplugprovidedthereinwithawalled chamber, a conducting member leading from the chamber to the ignition gap oi the plug, a second conducting member leading from the chamber and adapted for connection with an ignition lead, said conducting members being spaced apart at the chamber, a cartridge within saidchamber, said cartridge having conducting terminals and a non-conductive intermediate wall, the terminals o! the cartridge beingelectricslly connected with the said respective conducting members, and a body oi matter enclosed within said cartridge and in contact with the terminals thereof. said body of matter comprising a mixture oi pulverulent or granulated conductive and non-conductive materials ci substantially the same speciiic gravity. the particles of which are interspersed with respect to one another.

6. In an assembly o! the character described, a spark plug provided therein with a walled chamber, a conducting member leading trom the chamber to the ignition gap oi the plug, a second conducting member leading from the chamber and adapted i'or connection with an ignition lead. said conducting members being spaced apart at the chamber, a hermetieally sealed cartridge within said chamber, said cartridge having conducting terminals and a non-conductive intermediate wall, Ithe terminals of the cartridge being electrically connected with the said respective conducting members, and a body oi' matter enclosed within said cartridge and in contact with the terminals thereof, said body of matter comprising a mixture oi pulverulent or granulated conductive and non-conductive materials oi substantially the same speciiic gravity, the particles of which are interspersed with respect to one another.` l Y '1. Aspark plug embodying an insulating element provided therein with a chamber having a threaded open end and from the base o! which a passage extends to the inner end o! the insulating element, said passage being threaded adjacent`the chamber, a central electrode member having a threaded portion, said member extending through said passage and having threaded engagement with the threads thereof, a gasket coo l with said central electrode member to form a tight joint between said member and 8.Inanassembiyoithecharacterdescribed. asparkplugprovidedthereinwithawalled chamberzaconductingmemberleadingiromthe chambertotheignition gap oitheplug,asecondcmductingmemberieadingiromthechsml=ber and adapted for connection with an ignition rmediatewallbridgingthespacebetweensaidend walls and spacing them apart to form between the end walls and within the intermediate wall a closed chamber, a body of matter enclosed within said cartridge and in electrical contact with the conductive end walls thereof, said body oi matter comprising a mixture of pulverulent or granulated conductive and non-conductive materials.

10. A transformer for ignition circuits embodying a cartridge comprising conductive end walls forming terminals, and a non-conductive intermediate wall bridging the space between said end wallsandspacingthemaparttoiormbetween the end walls and within the intermediate wall a closed chamber, a body of matter enclosed within said cartridge and in electrical contact with the conductive end walls thereof, said body oi matter comprising a mixture oi pulveruient or 'granulated conductive and non-conductive materials, and an impervious sealing material sealing the joints between the end walls and the intermediate wall to hermetieally seal the interior oi the cartridge.

ARMEN A. KASARJIAN.

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