Spark plug



sept. l 11, 1923. J. ANDERSON SPARK PLUG Filed Nov. 4, 1919 Wl Tf1/E 8858 Wwf A TTRNEYS Patented Sept. ll, 1923. UNITED STATES JOHN ANDERSON, OF CHARLESTON, WASHINGTON. SPARK PLUG. Application led November 4, 1919. Serial No. 335,620. To aZZ 'whom t may concern: Be it known that I, JOHN ANDERSON, a citizen of the United States, and a resident of Charleston, in the countyl of Kitsap and State of Washington, have invented a new and Improved Spark Plug, of which the following is a full, clear, and exact description. v This invention relates to improvements in spark plugs, an object of the invention being to providel a leak-proof spark-plug which will have an all metal outer shell or surface and which can be readily ,assembled and taken apart as occasion may require. A further object is to provide a spark plug which is in the nature of an improve ment over the structure illustrated in my pending application filed August 16, 1919, and given Serial Number 317,989. With these and other objects in View the invention consists in certain novel features of construction, and combinations and arrangements of parts, as will be more fully hereinafter described and pointed out in the claim. In the accompanying drawings- Figure 1 is a view in longitudinal section illustrating a preferred embodiment of my invention; Figures 2 and 3 are similar views illustrating modifications; and Figure 4 is an enlarged view illustrating one of the metal covered asbestos gaskets. Referring particularly to Figure 1, 1 rep resents the body of my improved spark plug which is externally screw threaded at its inner end, as shown at 2, for attachment to the engine cylinder and is of two internal diameters forming an annular shoulder 3. 4 represents the core of the plug which may be of porcelain or any other suitable material and this core fits the interior of the body 1 and is provided with an annular shoulder 5 adjacent the shoulder 3, and a gasket 6 is provided between the shoulders 3 and 5 to render the juncture tight. The lower end of the bore 4 has a central recess 7 having a rounding taper and an outer tapering wall 8 so that the lower end of the core is sharp and is tapered externally as shown at 9, to prevent the accumulation of carbon thereon. The core 4 has a longitudinal central bore receiving a stem 10, the latter having a rounded head 11 located within the recess 7 and a gasket 12 is positioned between the head 11 which is rounded as shown and the inner end of the recess 7 so as to render the juncture gas tight. The upper end of the core 4 extends slightly above the end of body 1 and a gasket 13 lits around the core and is located against the end of the body. A pair of perforated disks 14, preferably of asbestos, are positioned against the end of the core 4 and above the gasket'13, and a nut 15 is screwed to the threaded upper end 16 o f stem 10 and serves to clamp the parts above described together. A metal top cap 17 having its lower end cupped is provided and is made with cen; tral screw threaded recesses 18 and 19 in its vlower and upper ends respectively with sufli- Ceives the screw threaded upper end 16 of v stem 10 and a gasket 20 is interposed between the cap 17 and the nut 15. A concave-convex centrally perforated spring 21 is positioned around the stem 10 within the cup of the cap and between the cap 17 and the nut 15 and exerts pressure on these parts acting as a nut lock and a compression member to hold all of the parts rigid after adjustment. The upper recess 19 receives a binding post 22 for the attachment of the necessary circuit wire. The term gasket is use d in a broad sense to cover any material, such as asbestos, which will be heat-proof and pressure-proof and, if desired, I may utilize a metal covered gasket such as indicated, but I do notl Wish to be limited in this particular. Referring to Figure 2, the body 23 is of two 'internal diameters, but the large-r internal diameter is at thetop instead of at the lower endl of the plug asin Figure 1, and this larger internal diameter is screw threaded for the reception of a threaded nipple 24 which serves to clamp anannular enlargement 25 on the core 26, and a gasket 27 is interposed between the enlargement 25 and the shoulder of the body. A small nut 28 is screwed onto the upper end of the stem with a gasket 29 interposed between the stem and the upper end of the core 26, and a spring 30 similar to the spring 21 .is interposed between the nut 28 and a cap 31 and within the cup of the cap. Gaskets 32 are located between the end of the cap and the nipple 24. In other respects, the construction is like the preferred form as above described. In Figure 3 I illustrate a modification of my invention in which the structure is very similar to Figure 1 except that a porcelain disk 33 is positioned between the cap 34 and the body 35 with interposed gaskets 36 and 37. rllhe stems 10 of all the forms of my invention have electric terminals 38 which are spaced from terminals 39 secured to the body so as to-form spark gaps, but the invention, of course, is not limited to any particular arrangement of terminals. t will be noted that with all forms of my improved plug the stems 10 are rendered gas tight by reason of the lower gaskets 12 and the upper gaskets clamped by the nuts. The space between the core and the body is rendered gas tight by reason of the gaskets located at the shoulders of the, core and also at the upper end of the core and these parts are clamped together by nuts independent of the cap nut, although the cap nut further facilitates the clamping action and is so constructed by reason of its recessed ends that no continuous passage of gas can be had general form and arrangement of parts dev scribed without departing from the invention, and hence I do not limit myself to the precise details set forth but consider myself at liberty to make such changes and alterations as fairly fall within the spirit and scope of the appended claim. v I claim A spark plug, comprising in'combination, a shell, an insulator within the shell, a stem electrode extending centrally and longitudinally of the insulator, a cap carrying wire connecting means upon its upper face and having its lower. face formed with a recess to provide a seat for the cap about the edge thereof, and the roof of the recess being formed with a threaded central bore adapted for receiving the upper end of the electrode, packing interposed between the seat of cap and the shell, and a spring washer carried upon the upper end of the electrode adapted for engaging the roof of the recess in the cap and thereby to hold the cap against turning movement. JOHN ANDERSON.



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