US2273651A - Spark plug - Google Patents

Description

M. H. LUDE Feb, 17,v 1942.

SPARKPLUG Filed Sept. 2e, 1940 lm; AI

fn deff/fr: Maw J7( wie u -Patented Feb. 17, 1942' 2,273,651 SPARK PLUG Max H. Lude, Greenville, lll., assigner to Thoma. & Gould Sales Company, St. Louis, Mo., a rm composed of Walter C. Thoma and Herman C.

Gould Application September 26, 1940, Serial No. 358,398 cclaims. (el. 12a- 169) This invention relates to spark plugs.

Objects of the invention are to provide an improved spark plug having a metallic shell adapted to be screwed-into a threaded hole opening into the combustion space of an internal combustion engine, and having a side electrode attached to its inner end and enclosing a central insulating body having a center electrode projecting beyond each end thereof, and means for securing said insulating body in said shell in either one of two positions to place either of said vcenter electrodes in cooperative relationship to the side electrode; to form said shell with means or passages through which air may be circulated to cool the spark plug and particularly said insulating body by currents or blasts of air driven through said passages by the usual fan mounted adjacent to the engine; to provide an insulation holder having an adjustable terminal for engaging the electrode on the outer end of said insulating lbody which is also in electrical communication with the center electrode that is in cooperative relationship with the side electrode; to provide means for venting or passing air through said insulation holder outwardly beyond the shell to cool the same and the parts contained therein; to provide novel center electrodes extending beyond opposite ends of the central insulating body and in electrical communication or contact with each other whereby the spark plug may be made to function properly irrespective of reversal of its position in the shell; to provide the central insulating body with `a novel formationof insulating shoulders affording more surface to transfer heat therefrom; to provide a terminal attaching screw adjustably mounted in the insulation holder whereby the position of said attaching screw may be varied or changed as required by the dimensions of the electrode in the central insulating body; and to provide suitable sealing gaskets arranged in a novel relationship between the elements of the spark plug to render the same completely impervious and leakproof.

Another object of the invention is to provide an improved central"insulating body having duplicate center electrodes extending from its opposite ends and'also having a non-blistering type of glaze on its end portions that are exposed to the combustion forces within the engine so as toprolong and extend the life of the spark plug, and also to provide blunt or rounded ends on the central insulating body to avoid spreading by compression, as sometimes occurs in spark plugs having concavities in the inner ends of the insulating elements supporting the center electrode.

Other objects will appear from the following description, reference being made to the annexed drawing, in which- Fig'. 1 is a side elevation of a spark plug embodying the present invention.

Fig. 2 is a longitudinal sectional view of the spark plug.

Fig. 3 is a side elevation of the reversible central insulating body having a center. electrode extending beyond each end thereof.

The metallic shell I is formed with an externally threaded end 2 which is adapted to be screwed into a threaded hole opening into the combustion space of an internal combustion engine. A side electrode 3 is attached to the inner end of the shell. The shell is formed with a circumferential shoulder 4 which is arranged to engage and compress a sealing gasket or Washer 5 against the engine body to provide a leak-proof joint. 'Ihe outer end 6 of the shell is polygonal and is adapted to be engaged by a wrench or the like to attach and detach the spark plug. The

shell is formed with a series of passages l through shoulder I3 in the shell and against the inner shoulder l0, thereby forming a leakproof seal.

In this assembly, a sealing gasket or washer Il seats-against the outer shoulder lI I. y

Electrodes I5 and I6 are embedded within the central msumting body and project beyond oppo-` site ends thereof so that, vwhen the spark plug is assembled, one of said electrodes extends slightly beyond the inner end of the shell adjacent to the outer electrode 3 in position to cooperate therewith vwhen enerized. The two electrodes, l5 and i6 are in electrical contact with each other by a telescoping joint I1, and each of saidelectrodes hasan enlarged circumferential flange or head I8 on its outer end. The ends I9 of the central insulating body are substantially iiat or blunt, as distinguished from the present practice of forming the yinner end of the insulation element supporting the single center electrode slightly hollow or concave. Forming the ends blunt or hat avoids spreading oi vthe insulation body around the center electrode by compression within the combustion chamber of the engine. These insulating elements may be made oi any suitable material, such as porcelain or glass or fiber. vThe ends are formed with a non-glistening type of glaze, as distinguished from the enamel type of glaze in order to cooperate with the shoulders lll and II to transfer or dissipate heat from the spark plug when in use A hollow tapered insulating element 2U extends into the outer end of the shell, encloses the outer end portion of the insulating body bearing the center electrode, and seats against the sealing gasket or washer I4. A clamping gland or nut 2l encloses and is attached to the inner end of the element 20 and screws into the internally threaded outer end of the shell, thereby clamping all of the parts rigidly in assembled cooperative relationship. The element 20 may be formed with a number of air passages 22 to permit flow of air therethrough to assist in cooling the spark plug. The nut orl gland 2| is formed with a wrench engaging polygonal portion 2l to facilitate attachment and detachment thereof.

vThe terminal 2l is screwed into a threaded hole in the outer end of the element 2li in order to effect electrical contact with the outwardly extended center electrode l5 or IB, depending upon the position of the insulating body Il within the shell. When either of the center electrodes becomes burnt or otherwise shortened, the spark plug may .be taken apart and the insulating body 8 reversed to place the damaged electrode at the outer end and the undamaged electrode at the inner end. The terminal element 24 may then be screwed further into the member 20 to effect electrical contact with the shortened or damaged electrode adjacent thereto. A flange or shoulder 25 is formed on the terminal 2l in position to permit longitudinal adiustment of said terminal as described, and still support the attached wire. A nut 2B is screwed on the threaded outer end of the terminal 2l to hold the wire clamped against the shoulder 2l.

The electrodes l5 and I6 are preferably cemented within the body 8 and held in rigid relationship therein by liquid porcelain cement or other attaching means.l

It should now be apparent that this invention constitutes an improved spark plug attaining all of its intended objects and purposes in a highly emcient, economical and satisfactory way. 'I'he 4spark plug may be made and sold at permissible,

cost and will endure substantially twice as long as spark plugs of standard construction having a single non-reversible and non-'replaceable center electrode. The invention may be varied x within the scope of equiv lent limits without de'-r and principle thereof.

tion, an insulating body removably mounted inA said shell, center electrodes projecting beyond the ends of said insulating body and adapted to cooperate with said outer electrode, means for supporting said insulating body inV alternativepositions in said shell in which either selected se of said center electrodes is adjacent 'to said against. said body, and a terminal adjustably4 supported by said element and adapted to engage the outer one oi said center electrodes.

f2. A spark plug comprising a metallic shell having an outer electrode attached to its inner end, a pair of oppositely extended center electrodes, an insulating body for supporting said center electrodes in alternative positions in which either selected one of said center electrodes is adjacent to said outer electrode and the other center electrode extends outwardly, an insulating element for clamping said body in said shell, a wire attaching terminal mounted in said element and insulated thereby from said shell and having electrical contact with said center electrode that extends outwardly, and means for conducting air through said shell for cooling the spark plug.

3. A spark plug comprising a metallic shell having an outer4 electrode attached to its inner end, a removable and replaceable insulating body supported in said shell, a pair of center electrodes extendingl .beyond the opposite ends of said insulating body, means for supporting said insulating body in alternative positions in said shell in which either selected one of said center electrodesis adjacent to said outer electrode. an insulating element engaging said body, a terminal attaching member adjustably suported by said element and insulated thereby'from said shell and having electrical contact with the outer one of said center electrodes, and a clamping gland engaged with said shell andsaid insulating element and holding said element and said body in rigid engagement with each other.

4. A spark plug comprising a metallic shell having an outer electrode attached to its inner end, a removable and replaceable insulating body supported in said shell, a pair of center electrodes extending beyond the opposite ends of said insulating body, means for supporting said insulating body in alternative positions in said shell in which either selected one of said center electrodes is adjacent to said outer electrode, an insulating element engaging said body, a terminal attaching member adjustably supported by said element and insulated thereby fromv said shell and having electrical contact with the outer one of said center electrodes, a clamping gland engaged with said shell and said insulating element and holding said element and said body in rigid engagement with each other, -and means for conducting air through said shell about said insulating body.

5. A spark plug comprising a metallic shell having an outer electrode attached to its inner end, a removable and replaceable insulating body supported in said shell, a pair of center electrodes extending beyond the opposite ends of said insulating body, means for supporting said insulating body in alternative positions in said shell in which either selected one of said center electrodes is adjacent to said outer electrode, an insulating elementengaglng said body, a terminal attaching member adjustably supported by said element and insulated thereby from said shell and having electrical contact with the, outer one of said center electrodes, a clamping gland engaged with said shell and said insulating element and holding said body and said element in rigid engagement with each other, and means for conducting air about the outer one of said inner electrodes.

6, A spark plug comprising a metallic shell having an outer electrode attached to its inner end, a removable and replaceable insulating body supported in said shell, a, pair of center electrodes extending beyond the ODPQSite .ends

'of' said insulating bodyand having'V electrical contact with each other within said body, means for supporting said insulating body in alternative positions in said shell to hold either selected one of said center electrodes adjacent to said outer electrode and to hold` the `other center "through out of communication with the interior v of said shell, a terminal attaching member ad justably supported by said element and having velectrical contact with the outer one of said center electrodes, and a clamping gland screwed in the outer end of said shell and holding said insulating .element and .said body in rigid relationship with each other and also in rigid relationship with said. shell,

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