US1208479A - Spark-plug. - Google Patents

Description

F. CARLSON.

SPARK PLUG.

APPLICATION FILED FEB. I. 191e.

5l/Witwen@ FREIDRICK CARLSON, OlE NORTH EASTON, MASSACHUSETTS.

SPARK-PLUG.

recente.

Specification of Letters Patent.

Patented lDec. 12, 1916.

l lAppli-cation` led February '7, 1916. Serial No. 76,659.

.North Easton, in the county of Bristol and State of Massachusetts, have invented cer-- tain new and useful Improvements in Spark Plugs; and I do declare the following to be a full, clear, and exact description of the y invention, such as will enable others skilled in the art to which it appertains to make and use thesame.

This invention relates to new and useful improvements in spark plugs, and the primary object of the invention is to provide a spark plug that will be foundvery efficient in operation, and also which is pro vided with an electrode that is self cleaning and will not become in any way choked during the operation of the plug.

A further object of the invention isto provide a device of this character which is simple and durable in construction, inexpensive to manufacture, and one which will be very efficient in operation. l

With these and numerous other objects in view, myinvention consists of the novel features of construction, combination and arrangementof parts which will herein be referred to and more particularly pointed out in the specification and claim.

lin the accompanying drawing: Figure 1 is a central vertical section of my improved spark lug; Fig. 2 is a centraly vertical section of) the plug showing the electrode and core in elevation; Fig. 3 is a detailelevation of the core and electrode removed from the plug; and Fig. 4 is a bottom plan view of the plug.

lln the general construction of my spark plug, the main parts are similar to those commonly used in' devices of this character, and they comprise an outer shellor casing 1 which has its lower end 2 externally threaded as shown at 3, so that the same may be screwed into the engine cylinder. Within the lower end 2 o f the casing 1 is formeda gas chamber A, for a purpose to be hereinafter more fully described. A suitable insulating core 4 preferably made of porcelain, and having an annular enlargement 5 intermediate its ends, is adapted to be positioned in the casing1, the enlargement of the same being positioned on an internal shoulder 6 in said casing. 'llhe core 4 is held in place by a retaining nut `7 as I clearly shown in Fig. 1 of the drawing. `The central insulating core 4 has its upper end projecting from the casing 1 as is common in devices of this character, while the lower end 8 of the same is contracted, and is ter minated av predetermined distance above the lower edge of the casing in the gas chamber A. l

The insulating core 4 is provided with a central longitudinally extending electrode 'rod 9 which extends therethrough and projects from the same at either end. A metallic cap 10 and binding nut 11 are screwed onto the upper end of the rod for the usual purposes, while the lower projecting end of said rod which is designated by the numeral 12 vextends from the core within the chamber A to a point adjacent the lower end of the same. Surrounding the rod 12 at the lower end of the core 4 is a steel washer 13 which will protect the terminal of the lower end 8 of the core. Positioned on the projecting lower end 12 of the rod 9 is a steel, substantially frusto-conical shaped electrode 14, which has its upper flat top positioned' against the bottom of the washer 13, while the sloping wall 15 of the same projects downwardly until it terminates at the outer edge 16 of the base 17, which is disposed adjacent the lower end of the casing. The base 17 is rounded and has its annular outer edge 16 when in position, spaced equi-distant from the lower end of thev casing 1. The upper flat top of the electrode is of a diameter equal vto the diameterof the washer 13 and when positioned against the lower surface of the Same, its outer edge will be disposed in alinement with the vouter edge of said washer. This washer 13, owing to the fact that it is of a size corresponding to the lower extremity of the core 4 against which 1t is positioned, has its outer edge alining with the circumference of the lower end of the core, so that when assembled, these parts will be all positioned in a single arc as clearly shown in Figs. 1, 2 and 3 of the drawing. l

When the parts of this plug are assembled and the frusto-conical shaped electrode is positioned against the Lower end of the core 4 -within the gas chamber A, `it will be noticed that the extreme outer edge 16 of the same will be positioned a short distance from the lower edgey of the casing, thereby forming'a circular communicating passage between the chamber A and the cylinder which is designated by the letter X.

When this device is in operation, the spark will jump from the edge 16 of the electrode to the adjacent portion of the lower edge of 'the-casing, and a large circular spark will be created by this gap which will be ample for any purpose to which this plug may be used. As soon as the spark ignites the charge in the cylinder, an explosion will take place in the gas chamber A, and the discharge of the expanded gases through the communieating passage that is formed by the spark gap at'X, will prevent any accumulation of carbon deposits on the wall-of the electrode by preventing the adhesion of lubricating oil and subsequent carbon deposited thereon due to the burning of such oils. kThis operation will make my improved spark plug selfcleaning and'will also prevent the same becoming choked up and stopped during its operation. T his operation forms one of the most essential features of this invention, and

lthe same is brought about by the peculiar construction of the electrode, that is so connected with the lower contracted end of the core that an arc is formed thereby which upon explosion in the gas chamber will direct all of the gases downwardly with full force against the sloping wall of the electrode. This brings about the self-cleaning action that will always keep the point adin its lower end, said chamber having an opening in its upper end larger than the open lower end of the same, a continuous uninterrupted downwardly beveled edge at said lower end of the chamber, an insulating core in the casing with its lower end extending downwardly in the gas chamber through the open upper end to form an annular chamber therein, said lower end of the core being arcuately contracted and terminating a short distance from the lower edge of said chamber, a centrally disposed electrode rod in the core extending from the lower end thereof, a washer on the lower end of said rod, a substantially frusto-conical shaped electrode in the lower end of said rod having a flat top engaging said washer and its lower edge spaced equi-distant from the upper portion of the outwardly beveled lower edge of the gas-chamber to form a spark gap therebetween, the wall of said electrode being arcuately curved and merging at its upper edge into the arcuately contracted lower end of the core to increase the area of the annular gas chamber at that point, and the lower power ofthe wall of said electrode being inclined outwardly at substantially the same inclination as the beveled edge of the gas chamber, whereby upon eX- plosion of the gases in the chamber they will be directed downwardly with `flull force against the wall of the electrode and hence out through the spark gap which will keep the said gap free from carbon.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

Y FREDRICK CARLSON( Witnesses: l

ARTHUR G. CARLSON, FRANK I. KEITH.

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