US1973884A - Carbonproof plug - Google Patents

Description

P 9 H. RABEZZANA 1,973,884

GARBONPROOF PLUG Filed Aug. 6, 1932 am ii; W9 Q 7 sorbing element 7, which as shown in the draw- 1 Prim d Sept. 1s, 1934 CARBONPROOF PLUG llector Rabeuana,

Flint, melt, Ym i.

none assignments, -to General Motors Como ration, Detroit, Mich, a corporation of-Delaian Application August 6, 1932, Serial No.- 627,684

' 4 Claims. (01. 123-169) This invention relates to ignition equipment for internal combustion engines, and'particularly to an improvement in spark plugs.

It is well recognized that the proper and elli- I cient functioning of a spark plug depends largely upon the temperature to which it is subjected during use. If a plug runs too.hot preignition troubles will result, and if it 'runs too cold, carbon or oil will deposit on the plug parts 10 and, short-circuitthe gap. To avoid fouling, 'the temperature of those portions exposed in the combustion chamber must be high enough t bur-{n away any products of combustion deposited thereon and yet below the point where preignition is likely to occur. For this reason a plug must be designed according to the type of engine it is to be used with and the temperature at which such-engine normally operates.

With these things in mindit is here proposed 20 to provide a spark plug especially adapted for a. relatively cool running engine and which em-.

bodies a heat absorbingportion having a comparatively large surface area exposed to the heat of combustion together with a restricted connection with the main body of the plug. Becauseof this arrangement, the dissipation or transference of heat taken upbythe heat absorbing portion will be retarded and at a rate to store up sufficient-heat to maintain the temperature high enough to burn away the carbon and keep the plug clean.

A better understanding of the invention will ,be vhad upon reference to the accompanying drawing, wherein, Figure 1 is aside elevation' 35. of a spark plug in operative position,v in an engine cylinder head, a portion of the head beingshown in section. Figure 2 is a vertical sectional view taken on line 2-'2 of Figure 1, and Figure Figure 2."

Referring tothe drawing, the reference numeral 1 indicates-a water cooled cylinder head of an internal combustion engine, having a combustion chamber 2. Positioned within an openl threaded skirt 3 of the outer metal shell 4, which as is usual in spark plug design encloses an iiisulator core 5 surrounding a central electrode 6.

At the lower end'of the skirt and directly ex-- posed to' the combustion chamber 2 is a heat ab'- ing, may comprise a relatively narrow ring presenting a large surface area to the heat, of com- 'bustion. This ring is connected to the main bodyof the-plug or skirt 3 by one or more re- 3 is a transverse-section taken on line 3-3 of ing through the wall of the head 1 is a screw strict/ed neck portions 8 which afford the only path for the flow of. heat absorbed by the ring 7 into the skirt 3, from whichthe heat is taken up by the head 1 and transferred to the cooling medium in the water jacket. Because of the co restricted path of heatflow and of the large surface area expos d to the heat, the temperature of the narrow ring 7 will be maintained at a considerably higher point than that of the remainder of the plug and thereby prevent the 5 accumulation of carbon deposits.

."In the manufacture of the plug, thering 7.

may be formed initially as a part of theskirt proper and laterseparated by a pair of saw kerfs cut inwardly from diametrically opposite points adjacent the inner end of the skirt.

To provide the spark gap, use is made of a side wire or grounded electrode 9 ending. in

.spaced relation to the central electrode 6, and

mounted on the underside of the ring 7, prefer ably in line with one .of the neck portions 8. By so mounting the sidewire, the heat taken up by it can be readily transferred through the neck and into the main .wall of. the skirt, so as to obviate harmful effects of too much' heat on 80, the side wire.- 7 I It will be understood that by varying the size df the heat absorbing element and its connection and relation to the 'main portion of the plug, the operating temperature thereof may be regulated in accordance with conditions of use. It will also be understood that various modifications may be made of the specific embodiment here referred to. 7 I claim: 1. A spark plug. shell having a pair -of saw kerfs cut therein adjacent its inner end from diametrically opposite points and extending throughout the major portion of the shell to afford air space insulation between the end por-,

tion and the shell with restricted neck portions therebetween, and a' grounded electrode wire mounted -on said end portion in alinement with one of said neck portions. I

2. A spark plug shell having a pair of trans- .100

verse saw kerfs cut from opposite sides thereof i immediately adjacent its inner end to aiford a narrow heat storing ring in axial alinement and integral with the main body of the shell, said saw kerfs being so 'related as to leave a bridge jacent itslinner end a saw kerf cut llO,

therebetween a restrictedf shell axis and immediately adjacent the inner end thereof to afford an opening through the wall thereof throughout a major part of its circumferential extent for breaking the heat flow path between the endmost portion and the main body of the shell.

H. RABEZZANA.

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