US2518844A - Spark plug - Google Patents

Description

Aug. 15, 1950 Filed Jan. 15, 1949 Patented Aug. 15, 1950 UNITED STATES PATENT OFFICE SPARK PLUG Guy r. Wetzel, Park Ridge, 111.

Application January 15, 1949, Serial No. 71,158

1 This invention relates to spark plugs and constitutes an improvement over the invention disclosed in my copending application, Serial No,- 22,157, filed April 20, 1948, now abandoned.

The spark plugs of said copending application and of the. present application include certain standard elements such as a grounded shell and insulated ignition electrode and a grounded electrode, together with one or more auxiliary electrodes which are also grounded. n

One of the objects of the present invention is one of the 3 Claims. Cl. 123-169) frequency discharge the spark occurs more readily and propagates faster through the combus tion mixturel Another object ofthe invention-is the provision of grounded electrodes as referred to, arranged in a novel manner so as to give asfree a path as possible to the ionized gas caused by the high ,frequency discharge in the combustion mixture, and as a consequence thereof rapid propagation .of

combustion is accomplished; as a corollary to this object, the grounded electrodesare. arranged so that there is a minimum of shielding of the spark,

in the spark gap with the result that the spark or flame propagates rapidly through the combustion mixture.

A further object is the provision of groundedi electrodes which are flat with narrow edges and are so arranged that the narrow edges are disposed adjacent the insulated electrode so that frequency discharge have thespark and the high greater eficiency.

A still further object of the invention the provision of flat grounded electrodes so arranged as to create a greater turbulence of the combus: tion mixture due to their positioning withtheir flat sides facing in the directions of normal move- Another object ofthe invention is the provi 5O sion of two or more grounded electrodes so ar-F ranged that one of them cooperates with the insulated electrode for causing a spark and the 0th er groundedelectrode produces a' high frequency ment of currents of the mixture.

discharge, and with the further provision that the two grounded electrodes more or less, alternatelybecome the ignition and-auxiliary electrodes respectively. r

A still further object of the invention is th provision of a spark plug for carrying out the objects referred to above which can be produced by ordinary manufacturing methods and without the necessity of extreme accuracy.

Still another object is the provision of a spark plug by means of which'cleaner firing action is accomplished as well as easier starting of the engine whether hot or cold.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my device whereby the objects contemplated are attained as hereinafter more fully set forth, pointed out in the claimsand illustrated in the accompanying drawings in which: I

Figure l is an elevational view of the spark plug embodying the present invention;

Figure 2 is an enlarged view of thelower part of Figure 1 with-a portion thereof shown in section;

Figure 3 is a bottom view of Figure 2;

Figure 4 is a view taken on line 4-4 of Fig ure 2;

Figure 5 is an enlarged detailed view of the electrodes graphically illustrating the actionbetween the electrodes;

showing-a modified form of grounded electrodes.

Referring now in detailto the drawings, the reference numeral l2 indicates generally a spark plug which forthe most part is astandardplug.-

" The details of-construction of the main part of grounded'with the frame of the engine.

spark plug includes ancentral ignition electrode. Hi which is insulated bymeansof an insulator I8,

an automobile.

the'lplug need not be dwelt upon except to point out that 'the plugincludes a. metallic shell [4 adapted to be threaded into a spark plug opening in an engine. The shell 14 is thereby. electrically- The from the shell I4 and is provided with a terminal 2 0 .for connection with the ignition circuit of The gr'ounded electrodes are designatedby the numerals Z4 and 26; The grounded electrodes 24 and 26 are substantially identical with each other and each comprises a fiat relatively thinstrip of material. The material of the grounded electrodes is any preferred alloy adapted for the purpose. The electrodes 24 and 26 may be connected in any suitable manner to the shell l, the latter having as usual an annular lower end. One way of securing the electrodes 24 and 26 to the shell l4 consists in electrically welding the electrodes thereto as illustrated in Figure 2. Thus, there is an electrically grounded connection between; the electrodes and. the shell. It will be understood that other means may be employed for securing the electrodes 24 and '26.

The grounded electrodes 24 and 26 are then bent toward each other as illustrated in the van ous figures. The discharge ends of theelectrodes are then twisted so that the fiat sides thereof are disposed vertically or in, planes extending longitudinally of the insulated electrode [6. The spark plug will at times be referred to as having a lower end, but it will be understood that this expression refers to vertical: positioning of the plug, and. is. to be interpreted according to therel'ativeposition in which the spark plug will be inserted in the engine.

"The numeral '26 indicates the discharge ends of' the grounded electrodes 24 and 2G. The discharge ends are disposed adjacent each other forming a gap 3'0 therebetween. As illustrated.

the gap 30 extendslongitudinally of the insulated electrode-and this gap is relatively small or on the order of from .01 to .025; however, I do not wish to "be limited toanyexact size of gap. A comparison of Figures Z a-rid 3- will show that the discharge ends 280i the grounded electrodes have a relatively long and-a relatively short trans verse dimensionor as stated above they are gen-- erally flat and thin. V The narrow edges of the discharge ends, or the edges across the narrow dimension, are disposed adjacent the lower end of the insulated electrode 16 forming therewith a gap" as indicated at 32. The gap '32 maybe of a dimension similar to the usual sparkgapabout by very slight inaccuracies in the dimen s'ions' of theelectrodesor in the forming process. For" all practical purposes and as iiudgedby'the naked eye there is no. difference between the lengths "of-these two gaps; however, due to the fact, that {articles such as electrodes ade never perfectg there is a very slight difference in the lengthsfo'f the two gaps and this difference ,is

usually only minor.

4 Figure shows-the electrode 2.4" closer to the insulated electrode ['6 and as a resultthereofa,

spark. gap issetup between'these two electrodes.

The solid lines L34 graphically illustrate ithat a spark "takes place between the. electrodes '24 and i6. .Tl edischarge. endof .the electrode. '26 :is, spaced a greater distance fromthe insulated-elec trode, |.6.- and as. a consequence there. is no. spark created (between these. electrodes. The dotted lines '36 illustrate graphically .a. .high frequency discharge Or corona effect emitted from thegrounded electrode 26.

As pointed out in the copending application referred to above, this phenomenon is not too well known, but it is known that there is some form of discharge. The discharge is invisible to the naked eye in the dark, but I have shown that the effects of the discharge can definitely be determined.

The spark occurring across the two electrodes 24 .and 16 eventually causes. some loss of metal from the electrode 24 due to electrical erosion. This is illustrated by the cut-out portion 38. The

- upper point of the electrode 24 will then eventually be spaced at a greater distance from the There- IB which then become the ignition electrodes.

' The. electrode. 24 then becomes the auxiliary electrode. and the high frequency discharge or corona effect will be emitted from the electrode 24 as illustrated in Figure 6.

Figure? illustrates a modified form of grounded electrode. In this instance the grounded electrodw are indicated at 40 and 42. The outer ends of these electrodes are of round wire which can be inserted by a press fit in holes inthe shell of the spark plug, or electrically welded thereto. The discharge-ends of theelectrodes are flattened as illustrated at 44, and are bent toward each other as in the previous embodiment. Thus, the discharge ends of the electrodes 3 53 and are similar to and arranged in a manner similar to electrodes 2 4 and 26, but formed from diiierent shaped material.

two grounded electrodes are provided and asfar as manufacturing methods are con-- cerned' they are identical; however, either one of them may become an ignition electrode and the "other an auxiliary electrode and their relationship will be reversed from time to time.

The high freque ncy discharge enters into the immediate area or the spark gap with the result that the fuel in that area is disturbed and desirable turbulence is created in the spark zone. a 'result'of'this'action, the spark becomes more effective, and combustion of the fuel accordingly becomes more efiicient. The actionmay be compared generally with disturbing the fire and creating a 'greaterir'ont to the fire or combustion and enabling it toipropagate faster.

The arrangement of the electrodes. with their relatively narrow edges disposed adjacent the insulated electrode it and theirfiat, sides extending longitudinally thereof, provides as wide a path, as possible ,for the propagation of the comhustion caused 'by thespark with amin'imum of shielding. or blanketing. The propagation, of the spark is generally'dow nwardly and divergent, and as illustrated ill-Figure 4 it will .be-seenthat the grdunded electrode 26 presents as-small asurface as possibletoward the insulated electrode, .or in other Words as greata space or ipath as possible isarranged so that. the spark and combustion may readily propagate through .the combustion chamber. :The arrangement 'of' the-grounded electrodes is also such that thecorona eiTect or hightrequency dischargecreates. as turbulent effect. as possible'because of theiact that it is permitted t0 emergeysidewise from the immediate area of the spark as well asrd-i-rectly into the sparkgap. .The; high frequency-discharge agitates the combustion mixture-to a considerable distance with the result, that =combustiongpropagates. rapidly therethrough.

A -f urthc v dv n ageof the. arrangementoi the grounded electrodes 24 and 26 resides in the effect they have in creating additional mechanical turbulence in the combustion mixture. The stroke of the piston and design of cylinder head sets up a turbulence or currents in the combustion chamber, and at the top thereof the combustion mixture normally travels horizontally more so than vertically. This horizontal movement results in the currents striking the flat sides of the grounded electrodes whereby a greater turbulence is set up in the gases of the combustion mixture. This is particularly true in the case of the electrode portions 28 of Figure 2 and 44 of Figure '7, although the upper portions of the electrodes 24 and 26 of Figure 2 that are secured to the shell are effective in causing turbulence in the gases travelling horizontally against their flat sides. The increase in turbulence has an advantageous effect in the propagation of the spark or flame throughout the combustion mixture as referred to above.

It will be understood that the number of the grounded electrodes need not be limited to two, but may be three Or more in number. In any case only one of the grounded electrodes will become an ignition electrode and form a spark gap with the insulated electrode.

It will be thus evident that I'have produced a novel spark plug which has a number of important advantages over conventional plugs among which are easier starting of cold engines; cleaner firing action whereby the plug will operate efiiciently under conditions which cause conventional plugs to fail because of fouling; and more effective sparking which causes the engine to run better. Because of the clean firing of the spark plug of the present invention it can be used about two numbers colder than conventional plugs.

Spark plugs embodying the present invention have been used in automobiles run over 10,000 miles with no appreciable deterioration, and the spark plug keeps much cleaner than conventional spark plugs.

It will be seen from the above that I have produced an effective spark plug which is simple to manufacture and although having numerous advantages is sufficiently like the conventional spark plug so that it can be made at low cost and therefore is a commercially practical spark plug.

While I have herein shown and described a particular embodiment of my invention, it will be understood of course that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modification or substitution of mechanical equivalents as fall within the true spirit and scope of my invention.

I claim:

1. A spark plug comprising a grounded shell, a central ignition electrode insulated from said shell, and a plurality of electrodes grounded to said shell, said grounded electrodes being rigid and fixed with respect to said shell and to said insulated electrode, the discharge ends of said grounded electrodes being bent toward each other into positions longitudinally beyond said insulated electrode, said discharge ends being fiat and having a relatively long and a relatively short transverse dimension, said long transverse dimension extending longitudinally of said insulated electrode, and said flat sides being thereby disposed in planes parallel with the longitudinal axis of said insulated electrode, said discharge ends forming a gap with said insulated electrode longitudinally beyond the latter, said discharge ends forming a relatively narrow gap between themselves in a position longitudinally beyond said insulated electrode, said discharge ends being close together and thereby forming an effectiveiy continuous flat surface of substantial transverse dimension for baflling combustion mixture flowing in directions transverse to said planes.

2. A spark plug comprising a grounded shell, a central ignition electrode insulated from said shell, and a plurality of electrodes grounded to said shell, said grounded electrodes being rigid and fixed with respect to said shell and to said insulated electrode, said grounded electrodes being of flat material having a relatively long and a relatively short transverse dimension, the ends of said grounded electrodes secured to said shell being positioned with their long transverse dimension disposed generally peripherally of said shell,

the discharge ends of said grounded electrodes being bent toward each other into positions longitudinally beyond said insulated electrode, said discharge ends being disposed with their long transverse dimension extending longitudinally of said insulated electrode, the fiat sides of said discharge ends being thereby disposed in planes parallel with the longitudinal axis of said insulated electrode, said discharge ends forming a gap with said insulated electrode longitudinally beyond the latter, said discharge ends forming a relatively narrow gap between themselves in a position longitudinally beyond said insulated electrode, said discharge ends being close together and thereby forming an effectively continuous fiat surface of substantial transverse dimension for baliiing combustion mixture flowing in directions transverse to said planes.

A spark plug comprising a grounded shell, a central ignition electrode insulated from said shell, and a plurality of electrodes grounded to said shell, said grounded electrodes being rigid and fixed with respect to said shell and to said insulated electrode, the ends of said grounded electrodes secured to said shell being of substantially round stock, the discharge ends of said grounded electrodes being bent toward each other into positions longitudinally beyond said insulated electrode, said discharge ends being fiat and having a relatively long and a relatively short transverse dimension, said long transverse dimension extendmg longitudinally of said insulated electrode, and said fiat sides being thereby disposed in planes parallel with the longitudinal axis of said insulated electrode, said discharge ends forming a gap with said insulated electrode longitudinaliy beyond the latter, said discharge ends forming a relatively narrow gap between themselves in a position longitudinally beyond said insulated electrode, said discharge ends being close together and thereby forming an efiectively continuous flat surface of substantial transverse dimension for baiiiing combustion mixture flowing in directions transverse to said planes.

GUY F. WETZEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,267,597 Schultz May 28, 1918 1,530,549 Flynt Mar. 24, 1925 1,538,870 Champion May 19, 1925 1,548,556 Schmidt Aug. 4, 1925 1,959,639 Pall-lson May 22, 1934

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