US2334203A

US2334203A - Spark plug

Info

Publication number: US2334203A
Application number: US420625A
Authority: US
Inventors: Henry K King
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-11-27
Filing date: 1941-11-27
Publication date: 1943-11-16
Anticipated expiration: 1960-11-16

Description

Nov. 16, 1943. H. K. KING SPARK PLUG Filed Nov. 27, 1941 IN V ENTOR Patented Nov. 16, 1943 UNITED STATES PATENT OFFICE SPARK PLUG Henry K. King, Bethesda, Md. v ApplicationNovember 27,1941, Serial No. 420,625

19Claims. (o1. res-169) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) My invention relates in general to spark plugs and has particular reference to'spark plugs utilizing a series of spark gaps as distinguished from the more conventional plug having only a single gap.

It has long been common practice to manufacture different types of plugs'for different fields of application. These can be divided in general in v to two classes. tively low temperatures require a hot plug, i. e., a plug designed to operate at a high temperature to prevent oil deposit thereon which otherwise would tend ot cause the plug to misiire, commonly referred to as fouling. n the other hand, engines which operate at relatively high temperatures require a cold plug, 1. e., a plug designed to operate at a low'temperature to prevent preignition which otherwise would tend to cause the plugto fire ahead of time.

In modern high powered combustion engines,

such'as for example those used onaircraft, it has long been a problem to design a spark plug which will give satisfactory performance throughout extremes in operating temperature conditions of the engine. When the engine is operating at'full power, its temperature is of course at a maximum and hence there is a tendency towards preignition of the plug, but when the engine is operating at minimum power its temperature is obviously also at a minimum and thus there is a tendency towards fouling.

It is therefore a broad object of my invention Engines which operate at rela-- to provide an improved spark plug for acombustion engine which will maintain a substantially uniform temperature and thereby'render satisfactory service throughout extremes in operating temperatures of the engine.

A specific object of my invention is to provide a spark plug having gaps in series in which I the base member forming the outer electrode is spaced from the outermost intermediate electrode to form a chamber therebetween to permit entry tailed description ac's theattached draw- With respect to the drawingin which like reference numerals indicate like parts;

Fig. 1 is a vertical section of a spark plug illustrating a preferred embodiment of my inven tion, and

Fig. 2 is abotto mplan view of the plug shown m Fig. 1.

With reference now in particular to 1, my

improved spark plug contains an inner or central metallic electrode 1 which is taperedslightly and cylindrical in contour; The'uppe'r portion of electrode I is made hollow so that this sec-.- tion will-have a relatively low heat conducting. capacity. This feature. of construction prevents overheating of the top of the plug which other wise might cause damage ,to the high voltage lead (not illustrated) which is attached to the top of electrode l in any well known manner.

- Surrounding electrode I are a plurality of

sleeves

3 and 5 made of any good conductive metal which form intermediate electrodes. These sleeves are also tapered to the contour of the centralelectrode and are electrically separated from each other and from the central electrode by means of

tapered sleeves

2 and 4 which may be made from any suitable non-conductor such as, for example, sheet mica, and preformed to size if desired. 4

Insulating sleeves

2 and 4 may extend for substantially the entire length of the central electrode l to increasethe gas sealing qualities of the plug.

Intermediate sleeve electrodes

3 and 5 terminate, however, at substantially the juncture between the hollow and solid portions of the central electrode. To fill the'space above these intermediate electrodes,iinsulating sleeves l and 8, also tapered and preformed if desired,'are positioned between

insulating sleeves

2 and 4, and 4 and 8 respectively.

An annular metallic member 9 having a frus'toconical shouldered portion I0 is provided for holding the alternately arranged electrode sleeves and insulating sleeves firmly in position with respect to the central electrode. Being tapered, the sleeves will of course be heating.

A shell H is provided for receiving the electrodes and contains an upper female threaded cylindrical portion 12 for receiving a cylindrical shielding member I3. A.lower male threaded tightened further upon and an outwardly flared portion formed on the central electrode I.

I'he lower cylindrical screw portion H of shell H receives the assembly of electrode and insulating sleeves and is spaced from the outer sur face of electrode sleeve by the particular construction of member 9 and insulatingjsleeve 6 to form a gas chamber 22 therebetween. The bot- "tom 'of portion I4 is turned inwardly. at v23 as 4 shown to form a gas nozzle 24 whereby the gases of combustion which .enter the chamber upon the compression stroke of the engine may be su b sequently dr'awn outwardly from .the' chamber with'a' high'velocity to render the gap selfcleaning.

' The hot gases circulating in chamber 22 also maintain the outer surface of electrode 5 at an elevatd temperature which is suflicient. to prevent fouling between this electrode and the inner wall of the lower portion M- of shell ll.

=It will -be noted that the intermediate sleeve electrodes 3 and {terminate at substantially the juncture between the hollow andsolid portions of'el'ectrode I, which juncture is formed substant-iallyatthe top of member 9 By providing a ;"coristruc'tion of thistype, that portion of the plug above-the intermediate electrodes 3 and 6 will ha've a-relatively lowheat' conductivity with f theresult that the greater part of the heat in the plug which will riserapidly from .the' spark area because of the highly conductive heat path prog vided bythe'metallic electrodes 3 and-5 and solid electrode 5 will be ;driven outwardly therefrom substantially a transverse'direction across a relatively high conductive heat path comprising member 9,'shell II and gasket H to theengine 7 block l5. This rapid dissipation of heat generated is effective to prevent local overheating of the electrodes in the area adjacent the-spark high temperatureoperating conditions.

' *The'operation of my improved plug is as follows: High voltage is supplied in any well known manner as from a spark coil, one side of which temperatures; paratively low, the plug will not .foul between is grounded, through a suitably insulated conducto'r to the-top of the centralelectrode I. .Since one side of the spark coil'isgrounded, as is also the engine block 15, an arc will be formed between the central electrode 1 and electrode 3 from whence it will jump to electrode and then to-b'ase portion [4.

Becapitulating, it will be evident that the structure which hasbeen described"- is a distinctive and meritorious advance in the art in that it'pro- -vides' a spark plug which-will render'satisfactory operation over extreme differentials in operating When thewtemp'erature is com- 1 "theouter electrode and intermediate electrode, "particularly-at the upper part of the chamber '22, where fouling is mostlikely to occur;- the gas action into and'out of chamber 22 across ,noz "zle"2'4-' renders the plugself-cleaning; and the highly conductive heat path furnished by the central and intermediate electrode assembly serves to prevent local overheating of the electrodes in the area adjacent the spark gap when the operating temperature is high to thereby minimize possibilities for preignition.

In conclusion, it will be evident to those skilled in the art that various changes may be made in "the form, details of'construction and arrangement of parts herein described without departing from the spirit and scope of my invention. I therefore desire it to be understood that only such limitations as are imposed by the prior art shall be placed upon the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

' Having now fully described my invention, what .I claim is:

1. In a spark plug utilizing spark discharge .4 between a plurality of gaps in series, the combination comprising an inner electrode, at least one sleeve of conductive material constituting an intermediate electrode, the bottom edge of said conductive sleeve forming an annulus coplanar with the bottom edge of said inner electrode, means for insulating said inner and intermediate electrodes from each other, and a hollow base portion forming an outer electrode, the inner' wall of said base portion being spaced fromthe exterior surface of the outermost intermediate electrode to form a chamber therebetween.

2. The combination of claim'l wherein the chamber has a reduced cross-sectional area at the spark path between the intermediate electrode and the outer electrode to form a gas nozzle. I

, 3. In a spark plug utilizing spark discharge between a plurality of gaps in series, the combination comprising an inner electrode, at least one annular sleeve of conductive material ar- ""pathand will thereby 'prevent preignition under ranged coaxially therewith and forming an intermediate electrode, an annular sleeve of nonconductive material for insulating said inner and intermediate electrodes from each other, and a tubular male threaded base portion disposed coaxiallywith said electrodes forming the outer electrode, the inner wall of said base portion being spaced from the exterior surface of the outermost intermediate electrode to form a gas ,chamber therebetween for rendering the spark gap self-cleaning, said chamber having a, relatively small area adjacent the spark path and a substantially greater area thereabove.

4. In a spark plug utilizing spark discharge between a plurality of gaps in series, the combination comprising an inner electrode, a plurality of annular sleeves of conductive material forming intermediate electrodes, sleeves of non-conductive material for insulating the inner electrode from the intermediate electrode nearest thereto and for insulating the intermediate electrodes from each other and a tubular base member forming the outer electrode, said base surrounding said inner and intermediate electrode assembly and being spaced therefrom to form a gas chamber between the inner wall of said base and the exterior surface of the outermost inter- -media'te electrode.

5. The combination of claim 4 characterized by the fact that the cross-sectional area of the chamber at thespark path between the outermost intermediate electrode and theouter electrode is reduced to form a gas nozzle.

6. In a spark plug utilizing spark discharge between a plurality of gaps, the combination comprising a tapered inner electrode, a plurality of tapered conductive sleeves disposed coaxially with said inner electrode and formingintermediate electrodes, said intermediate electrodes being arranged to provide a spark path thereacross normal to the longitudinal axis of said inner electrode, insulating means for electrically separating the inner electrode from the intermediate electrode nearest thereto and for electrically separating the intermediate electrodes from each other, and a tube like body member forming the outer electrode, said bodymember being disposed coaxially with said inner and intermediate electrodes and spaced therefrom to form a gas chamber between the inner wall of said body member and the exterior surface of the outermost intermediate electrode.

7. The combination of claim (i-wherein the cross-sectional area of the gas chamber at the spark path between the intermediate and outer electrode is reduced to form a gas nozzle.

8. In a spark plug utilizing spark discharge between a plurality of gaps, the combination comprising a tapered central electrode, a plurality of annular conductive sleeves of frusto-conical contour disposed co-axially with said central electrode and forming intermediate electrodes, sleeves of insulating material for separating the sleeves of conductive material surrounding said 1,1 In a spark plug, the combination comprising a tubular male threaded bas member for screw insertion into a gas chamber and serving as an outer electrode, a tapered central electrode, intermediate electrodes comprising tapered of said central and intermediate electrodes projecting downwardly into said base member and,

terminating co-planar with the bottom thereof to formseries spark gaps between central and.

outer electrodes, and an annular gas chamber the sides ofwhich are formed by the inner surcentral electrode from the intermediate electrode nearest thereto and the intermediate electrodes from each other, and a tubular base member forming the outerelectrode, said base member being disposed coaxially with said central and intermediate electrodes and spaced therefromto form the side walls of a gas chamber between the inner wall of said base member and the exterior surface of the outermost intermediate electrode, the inner diameter of said base member adjacent the spark path being such as to form a nozzle for gas entry into said chamber.

9. In a spark plug, the combination comprising a tubular base member for insertion into a gas explosion chamber and serving as an outer electrode, a central electrode, at least one'sleeve of conductive material forming an intermediate electrode, said central and intermediate electrodes projecting downwardly into said base member and terminating co-planar adjacent the bottom of said base member to form series spark gaps thereacross, insulating means for electrically separating the central from the intermediate electrodes, and a gas chamber formed by the inner surface of said base member and the outer surface of the outermost intermediate electrode.

10. In a spark plug, the combination comprising a tubular male threaded base member for screw-insertion into a gas explosion chamber and serving as an outer electrode, an inner electrode, at least one sleeve of conductive material face of said base memberand the outer surface of the outermost intermediate electrode, theyinner diameter of said base member adjacent the spark path being restricted to form a nozzle for gas entry into saidchamber.

12. In a spark plugutilizing a spark discharge between a plurality of gaps'in series, the combination comprising a central electrode, said el'e'c 'trode having a lower solid portion and-an upper hollow portion, at least one sleeve of conductivematerial forming an intermediate electrode, said intermediateelectrode being terminated at substantially the juncture of the solid and hollow portions of said inner electrode, a base portion forming the outer-electrode and means for insulating said electrodes relative to each other.

1:3. In aspark plug utilizinga spark discharge betweena pluralityof gaps inseries, the combmationcomprising a centralelectrode, saidelectrode having lower solid and upper hollow por tions, at least one sleeve of conductive material forming an intermediate electrode, means for insulating said intermediate electrode from said inner electrode, said. inner and intermediate electrodes being tapered and having their bases of larger diameter projecting downwardly into said base member and terminating co-planar with the bottom edge of said base member to form series spark gaps thereacross and a gas chamber formed by the inner-surface of said base member and the outer'surface of the outermost intermediate electrode, the inner diameter of said base member adjacent the spark path being restricted vmediate and outer electrodes is reduced to arranged coaxially with said central electrode to form an intermediate electrode, said conductive sleeve being terminated at substantially the juncture between-the solid and hollow portions of said central electrode, aninsulatingsleeve disposed between said electrodes and a base portion forming the-outer electrode into which the lower portions of said central and intermediate electrodes are projected to form a series of gaps therebetween, the inner surface of said base portion being spaced from the exterior surface of the outermostintermediate electrode to form a gas chamber therebetween to render the plug self-cleaning.

14. In a spark plu the combination comprising a base member for insertion into a gas exiplosio'n'c'hamber' and serving asan outer electrode, a central electrode having a lower solid portionand an upper hollow portion, at least one intermediate electrode, the top of said intermediate electrode being terminatedsubstantiaHy adjacent the juncture-between thesolid andhol-v lowportions of said central electrode and the bottom thereoi-beingterminated co-planar with the. bottom of said base member to form, a series ,of spark gaps-between said central" and outer electrodes, means for-insulatin said central and each of said intermediate electrodes from one another, and separator means including an insulating'member for spacing theinner surface ofsaid base member from the exterior surface .oi said outermost intermediate electrode to form a chamber at the spark path betweensaid-interform 9. gasnozzle.

g to form a nozzle for gas entry into said chamber.

-16. In a spark plug the combinationcomprising a base member for insertion into a gas explosion chamber and serving as an outer electrode, a tapered central electrode, said electrode being hollow above the primary path of heat flow away therefrom and solid therebelow, at least one tapered sleeve of conductive material arranged coaxially with'said central electrodeto form an intermediate electrode, the. top end of "-said sleevebeix'ig terminated at substantiall the jun'cture between the solid and hollow portions of-said central electrode and the-bottom end thereof being terminated co-planar with. the bot- -tom end of said base member to forma series of -spark gaps, non-conductive means for insulating said central and each of said intermediate electrodes from one another for substantially their entire-lengths and: separator meansincluding a non-conductive member for spacing the inner surface of said base member from the exterior -surface of said outermost intermediate electrode to "form a gas chamber therebetween. whereby said-plug is rendered self-cleaning ing a base member for insertion into a gas explosion chamber and serving as an outer electrode', a tapered central electrode, said electrode being hollow above the primary path of heat flow away therefrom and solid therebelow, at least one tapered sleeve of conductive material arranged coaxially with said central electrode to form an intermediate electrode, the top end of said sleeve being terminated at substantially the juncture between the solid and hollow portions of said central electrode and the bottom end thereof being terminated co-planar with the bottom end of said base member to form a series of spark gaps, non-conductive sleeves for insulating said central and each of said intermediate electrodes from one another for substantially their entire lengths and separator means including a non-conductive V sleeve for spacing the inner surface of said base member from the exterior surfaceof said outermost intermediate electrode to form a gas chamber therebetween whereby said plug is rendered self-cleaning. 4

19. The combination of claim 18 characterized by the fact that the transverse sectional area of said chamber at the spark path between said intermediate and outer electrodes is reduced to form a gas nozzle.

HENRY K. KING.