Spark plug for internal combustion engine

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SPARK PLUG FOR INTERNAL Spark plug electrodes made of an oxidation resistant tita COMBUSTION ENGINE nium compound dispersed in a noble metal containing matrix are taught by Kanemitsu Nishio et al. in U.S. Pat. No.

FIELD OF INVENTION 4,427,915 issued on Jan. 24, 1989, which is another example of tackling the problem of Spark erosion due to oxidation. It

This invention is related to Spark plugs utilized in internal is noted, however, that the Spark plug electrodes described in combustion devices, Such as automotive engines and Similar U.S. Pat. No. 4,427,915 are likely to be costly to manufac devices combusting hydrocarbon containing fuel. ture.

BACKGROUND OF THE INVENTION In another approach to improving Spark plug performance, the likelihood of formation of carbonaceous

Internal combustion engines running on hydrocarbon deposits and oxidation on and between Sparking Surfaces is fuels usually require a Spark plug to trigger combustion. reduced by injecting hydrogen gas, oxyhydrogen gas, oxy Spark plugs are understood to be essentially comprised of gen or atomized water into the Spark gap between the two electrodes Separated by an insulator and Some form of electrode Surfaces. There are other known methods for a Support Structure which can be air-tightly fitted in a 15 introducing gases Such as hydrogen, utilizing injection combustion engine, Such that the two electrodes are devices, for Supplementing the fuel combustion efficiency of immersed in the atmosphere of the combustion engine. The an internal combustion engine. A device for introducing electrodes are at different electrical potentials, most often the hydrogen and oxygen gases into the Spark gap is described electrode in contact with the engine housing acts as ground in U.S. Pat. No. 4,343,272 issued to A. C. Buck on Aug. 10, and the potential of the central electrode is periodically 1982. One of the attendant difficulties in this approach is that raised to a higher potential, thereby generating a Spark, injection of the gases needs to be carefully Synchronized however, a reversed polarity of the applied potential is also with engine operation, furthermore Separate gas containers possible. The Spark dissociates and activates the molecules need to be accommodated. All in all, gas injection through of the gas located in the gap between the respective Surfaces a nozzle operated in conjunction with a Spark plug requires of the electrodes, thereby creating a plasma of activated gas 25 a fairly complex System.

atoms or radicals, which then ignites the air and hydrocarbon It is noted that engines designed to run on only hydrogen containing fuel mixture in the combustion engine. It should as fuel, generated by heating metal hydrides are also known, be clear from the foregoing that to ensure that the combus but Such Systems do not require conventional Spark plugs, tion device is working Satisfactorily, it is of importance that and at any rate, hydrogen engines represent a completely the Spark gap width between the electrode Surfaces is different approach to the problem.

essentially kept constant, the electrode Surfaces are clean, A process utilizing LaNish in a Spark plug is described the electrodes are separated by adequate insulation, and in in SU 1368936, issued in the former Soviet Union on Jan. the absence of electrically conducting Surfaces detrimental 23, 1988, to Kudryash et al. The role of the metal hydride is to plasma generation. To meet these requirements the build to provide nascent hydrogen diffusing through a ceramic up of deposits on the electrode Surfaces and on the adjacent 35 oxide barrier into the Spark gap to enhance ionization when insulator Surfaces, as well as Surface layers of oxidation the Spark is struck. However, nascent or atomic hydrogen in products of the electrode materials are to be avoided, all of amounts which is Sufficient to have a notable effect on the which are likely to lead to misfiring and/or irregular firing of efficiency of ignition in the Spark plug is generated only the Spark plug. It is known that over-heating of the electrode when the engine is hot. Moreover, the atomic hydrogen is Surfaces can lead to oxidation and Spark erosion, on the other 40 likely to recombine in the Spark gap to molecular hydrogen hand, under-heating may lead to carbonaceous deposit for before it can be utilized for increasing the Spark plug mation. Such deposits are frequently encountered in the efficiency. The spark plug of SU 1368936 requires a separate course of operating conventional Spark plugs, and are usu heater to generate hydrogen from the hydride when the ally formed by build-up of soot, pyrolytic carbon or high engine is cold. The hydrogen is generated as the engine and melting point hydrocarbons Such as waxes, which in turn 45 the Spark plug attached to it, attain Sufficiently high may be the consequence of incomplete combustion, tem temperature, and not limited to instances of ignition of the perature variations within the engine, fuel mixtures having fuel mixture. In other words, a substantial portion of the inadequate composition, and Such like. The above deposits hydrogen generated by the metal hydride is not used in the are particularly deleterious, affecting adversely the firing of Sparking Step, thus the hydrogen Source is likely to get the Spark plug electrodes and hence the combustion of the 50 exhausted early in the life of the Spark plug. lean fuel-air mixtures which is often utilized nowadayS. The object of the present invention is to utilize a metal Oxidation and Spark erosion of the electrode Surfaces will hydride for enhancing the efficiency and control of hydro also undermine the efficiency and lifespan of the Spark plug. carbon fuel ignition in a Spark plug without relying on Furthermore, misfiring of a Spark plug may result in the engine heat or without a need for an additional heater and a production of nitrous oxides, as well as oxidation of Some 55 ceramic oxide barrier to be incorporated in the Spark plug. fuel additives which may then result in toxic by-products STATEMENT OF THE INVENTION leading to undesirable and noxious components in the exhaust gases. An improved Spark plug to be utilized in conjunction with There have been several known methods to improve the been a hydrocarbon fuel burning internal combustion engine has performance of Spark plugs. One of Such developments have 60 found. The improved Spark plug is comprising: been modifications made to Spark plug geometry. Such i) two electrodes spaced from one another by a Spark gap, modifications are described, for example, in U.S. Pat. No. wherein one of Said the electrodes comprises an elec 4.015,160 issued to Lara et al. On Mar. 29, 1977. Other trically conducting metal hydride; attempts have been directed to improving ionization in the ii) an insulator member separating said electrodes from gas phase by changing the geometry of the Spark gap in a 65 one another, particular manner, Such as for example, described in U.S. iii) a housing Supporting said electrodes and said insulator Pat. No. 3,911,307 issued to Goto et al. on Oct. 7, 1975. member, Said housing adapted to be mounted within

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Said internal combustion engine whereby Said elec The metal hydrides utilized in the present Spark plug are trodes and Said internal combustion engine are capable often readily produced by heating the metal or metal alloy in of coordinated operation; and wherein one of Said a hydrogen atmosphere. At any rate, the method of produc electrodes is adapted to be connected to an electrical tion of suitable metal hydrides is beyond the scope of the energy Source and the other of Said electrodes is con present invention.

nected to ground. FIG. 1a shows Schematically a conventional Spark plug, BRIEF DESCRIPTION OF THE DRAWINGS where reference numeral 1 represents a metallic housing or FIG. 1a shows a Spark plug of the present invention, body, which Supports the Spark plug electrodes and fits into having a metal tubing packed with a metal hydride as one of the engine compartment in the usual manner. Electrode 4 is the electrodes.

attached to the housing 1. Electrode 4 and the housing may be made of the same metal, or different metals. It is usual but

FIG. 1b shows the cross-section of the metal hydride not necessary, that the housing and the electrode in contact electrode. with the housing are at ground potential. The other electrode FIG. 2 is a Schematic diagram of the Spark plug of the 5 of the Spark plug is constructed of a metal tubing 11 packed present invention having one electrode made of a metal 15 with a metal hydride 12, Such as for instance, titanium hydride connected to and Supported by a metal housing. hydride or copper-manganese hydride. Tubing 11 is most The preferred embodiments of the invention will be conveniently made of copper or an alloy of copper, but other described below with reference to the drawings. metals of high electrical conductivity and appropriate AS has been discussed above, Spark plugs are devices mechanical Strength may also be used. Insulator ring 2 is designed to initiate ignition of the fuel mixture in the engine fitted air-tightly into housing 1, enclosing metal conductor compartment by providing ionization or plasma in coordi tubing 11. The Spark gap is indicated by reference numeral nated operation with the Stroke of an internal combustion 6. As shown, in this embodiment electrode 5 is connected to engine. Ionization or plasma is generated by Striking a Spark battery 7, thereby it can be Subjected to an electrical poten between the electrodes of the Spark plug. The present tial. The application of an electrical potential to electrode 5 invention is not concerned with the geometry of the Spark 25 is coordinated by conventional means with the working of plug or the Spark gap, only with the composition of the the combustion engine. FIG. 1b depicts the cross-section of material of which at least one of the electrodes is con electrode 5 in the direction of arrows 3, showing metal Structed. tubing 11 packed with metal hydride 12. The metal hydride There are several metals which are known to be able to may be compacted as metal hydride particles into the tubing incorporate hydrogen in their structure. The hydrogen may 11, or the metal or metal alloy particles may be packed form a Stoichiometrically defined compound or alloy with tightly in a non-hydride forming metal tubing and Subse the metal, or may be dissolved or occluded in the Structure quently heated in a pressurized hydrogen containing atmo of the metal in an ordered or disordered configuration. In the sphere. Other methods for encasing metal hydride are also following discussion metal hydride is understood to mean acceptable, as long as the evolution of atomic hydrogen both metal-hydrogen compounds, and hydrogen dissolved 35 coincident with the generation of Spark can proceed in the or/and occluded in a metal and forming Stable or meta-stable Spark gap.

compositions with the metal under consideration. Typically Another embodiment of the improved Spark plug is shown such metal hydrides will include titanium hydride, nickel on FIG. 2. Like numerals indicate like elements of FIG. 1a. hydride, copper-nickel hydride, copper-manganese hydride, Electrode 8 may be made of the same metal as housing 1, or titanium-zirconium hydride or a similar transition metal 40 it may be a different metal or alloy. Electrode 9 is made of alloy hydride which may be regarded as a chemical an hydride of an hydride forming metal or an alloy of Such, equivalent, and palladium which readily dissolves, occludes which is Supported in electrical contact with housing 1. The or absorbs hydrogen reversibly. The hydrogen can be surfaces of electrodes 8 and 9 are spaced from one another released either from the bulk of the metal hydride or from by Spark gap 6. It is convenient to first make the metal of the Surface of the metal hydride under certain circumstances. 45 electrode 9 into the required shape, and Subsequently Subject All the metal hydrides referred to above are electrical the metal of the desired configuration and shape to hydri conductors. dation at high temperature in a pressurized hydrogen con It has been found that if one of the Spark plug electrodes taining atmosphere. Other methods known to the technically incorporates a metal hydride, Such as those discussed above, skilled to obtain an electrically conductive metal hydride of nascent or atomic hydrogen may be generated when the 50 the desired shape and configuration may also be used. electrode is Subjected to an electrical potential difference or The advantages of the above described Spark plug for connected to an electrical power Source, Such as a battery. It internal combustion engines include that it can be assembled is an important feature of the invention that the metal from conventional Spark plug elements and that the metal hydride utilized is stable enough not to release hydrogen hydride bearing electrode may also be readily and relatively naturally at the working temperature of the Spark plug, that 55 inexpensively produced. Furthermore, the nascent or atomic is at the normal running temperature T of the engine. In hydrogen is generated within the body of the electrode or by other words, the threshold temperature T, at which the desorption from the electrode Surface, only when the Spark metal hydride Starts to release hydrogen in notable amounts, electrodes are Subjected to an electrical potential difference, is higher than the working temperature of the internal that is, only when activation of the gas in the Spark gap is combustion engine: T>T. Furthermore, the hydride in the 60 required. Thus the reservoir of atomic hydrogen within the present invention is required to be an electrical conductor electrode of the Spark plug of the present invention is not under the working conditions of the Spark plug. Most metal readily depleted. Furthermore, the energy required to oper hydrides retain the hydrogen atom in the interstitial positions ate the Spark plug may be reduced, Since the energy required of the metal lattice, thus the metal hydride usually has a wide to yield atomic hydrogen under the operative conditions of composition range and hence, it will be able to emanate 65 the present invention is notably less than the energy con hydrogen in a relatively wide Span of applied electrical Sumed in the dissociation of hydrogen molecules of con potential. ventional Spark plugs.

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The embodiments of the invention in which an exclusive titanium-zirconium hydride and alloys thereof, and occluded property or privilege is claimed are defined as follows: hydrogen containing palladium metal. 1. An improved Spark plug for utilization in conjunction 3. An improved Spark plug for utilization in conjunction with a hydrocarbon fuel burning internal combustion engine, with a hydrocarbon fuel burning internal combustion engine, comprising: 5 comprising:

two electrodes Spaced from one another by a Spark gap, two electrodes Spaced from one another by a Spark gap, each electrode being adapted to be connected to a pole each being adapted to be connected to a pole of an of an electrical energy Source, wherein one of Said electrical energy Source, wherein one of Said electrodes electrodes comprises an electrically conducting metal is made of a hydrided metal capable of forming an hydride packed into a non-hydride forming metal tub electrically conducting hydride; ing in electrical contact with Said one of Said elec an insulator member Separating Said electrodes from one trodes; another, and a housing Supporting Said electrodes and Said insulator an insulator member Separating Said electrodes from one member, Said housing adapted to be mounted within another, and 15 Said internal combustion engine, whereby said elec a housing Supporting Said electrodes and Said insulator trodes and Said internal combustion engine are capable member, Said housing adapted to be mounted within of coordinated operation;

Said internal combustion engine whereby Said elec wherein one of Said electrodes is adapted to be connected trodes and Said internal combustion engine are capable to a first pole of the electrical energy Source and the of coordinated operation; other of Said electrodes is connected to a Second pole of wherein one of Said electrodes is adapted to be connected the electrical energy Source. to a first pole of the electrical energy Source and the 4. An improved Spark plug as claimed in claim 3, wherein other of Said electrodes is connected to a Second pole of Said metal capable of forming an electrically conducting the electrical energy Source. hydride is Selected from the group consisting of titanium, 2. An improved Spark plug as claimed in claim 1, wherein 25 nickel, copper-manganese alloy, copper-nickel alloy, Said electrically conducting metal hydride is Selected from titanium-zirconium alloy and palladium. the group consisting of titanium hydride, nickel hydride, copper-manganese hydride, copper-nickel hydride, k k k k k