US3872338A - Spark plug - Google Patents

Abstract

A spark plug in which the points are covered by a non-conducting material and in which a space between the non-conducting material constitutes the spark gap for ignition of a fuel mixture. In certain embodiments of the invention the spark plug has electrodes constructed and arranged to produce a plurality of sparks during each firing cycle of the plug.

Description

United States Patent 1 1 1111 3,872,338 Wax 1 1 Mar. 18, 1975 541 SPARK PLUG 3,017,532 1/1962 Talmey .3313/141 1 T 41 [76] Inventor: Bernard Wax, 38 Highland Ave., 3 538 372 970 m0 X Succasunna, NJ. 07876 FOREIGN PATENTS OR APPLICATIONS 2 Filed; July 23 197 714,756 9/1931 France 313/130 [21] Appl' 38l758 Primary ExaminerAlfred I... Brody Attorney, Agent, or Firm-Rudolph J. .lurick [52] US. Cl 313/130, 313/123, 313/141 [51] lltt. Cl H01! 13/20, HOIt 13/46 57 ABSTRACT [58] held of Search ..313/118,141,13(),128,

38/141 130, 131; 123/169 E, 169 EL A spark plug 111 which the points are covered by n 169 P 169 PA 169 PB 169 PH non-conducting material and in which a space hctween the non-conducting material constitutes the [56] References Cited spark gap for ignition of a fuel mixture. In certain embodiments of the invention the spark plug has elec- UNITED STATES PATENTS trodes constructed and arranged to produce a plurality 1,872,778 8/1932 McDougul 123/169 EL of Sparks during each firing cycle f the plug 2,028,749 l/1)36 .Iuhr ct n1 313/14l.l X 2,981,860 4/1961 Suter 313/131 R 2 Claims, 7 Drawing Figures r l I, 1 I I l SPARK PLUG BACKGROUND OF THE INVENTION In use, the electrodes of a spark plug are subjected to electric and chemical erosion which not only limits the useful life of the plug but, also, necessitates frequent cleaning of the electrode tips and adjustment of the spark gap length. Various arrangements have been proposed to overcome this problem.

US. Pat. No. 2,391,455, issued Dec. 25, 1945 to Franz R. Hensel discloses a spark plug in which the electrodes are made of various metal compositions having a high tensile strength and increased resistance to gaseous attack at high temperatures.

US. Pat. No. 1,515,866, issued Nov. 18, 1924 to L. F. Martin, discloses spark plug electrodes having tips plated with a metal having a high heat conductivity and providing a non-oxidizable surface.

The arrangements heretofore proposed for solving the problem of erosion of spark plug electrodes result in varying degrees of improved operating results as they are directed to decreasing the rate at which erosion takes place. However, they do not completely solve the problem as the spark for ignition of the fuel mixture jumps directly between two metal surfaces or points.

In a spark plug made in accordance with this invention, the ends of the electrodes across which the spark is generated are encased in a high temperature, nonconducting material, thereby eliminating electric and chemical erosion of the electrode ends, which results in a long operating life.

SUMMARY OF THE INVENTION A spark plug having electrodes for connection to a source of ignition voltage, the electrodes having spaced tips imbedded in an electrical insulating material. An air gap is provided in the insulating material, which gap constitutes the spark .gap for ignition of a fuel mixture. 7

In specific embodiments of the invention, the spark plug includes more than two electrodes having tips imbedded in an insulating material, thereby to provide a plurality of sparks during each firing cycle of the plug.

An object of this invention is the provision of spark plug having electrodes constructed and arranged to eliminate erosion thereof during use.

An object of this invention is the provision of a spark plug in which the spark for ignition of a fuel mixture is generated across an air gap defined by spaced nonconducting materials.

An object of this invention is the provision of a spark plug having electrodes for providing a plurality of sparks during each firing cycle of the plug, each of the electrodes having tips covered with non-conducting material.

The above-stated and other objects and advantages of the inventionwill become apparent from the following description when taken with the accompanying drawings. It will be understood, however, that the drawings are for purposes of illustration and are not'to be construed as defining the scope or limits of the invention, reference being had for the latter purpose to the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like reference characters denote like parts in the several views:

FIG. 1 is a sideelevational view'ofaesinglegap spark plug made inaccordance with onerenibodiment of this invention, certain parts being ShbWIlin. section;

FIG. 2 is a fragmentary cross-sectionalviewshowing a single gap spark plug made in'zaecordance' with' another embodiment of this invention;

FIG. 3 is abottom-plan view showinga'itwo-gap spark plug made in accordance with another embodiment of this invention, certain'partsbeingbroken away;

FIG. 4 is a fragmentary, crossssectional'view taken along the line 4--4'-of FIG. 3;

FIG. 5 is a fragmentary, .cross-sectiona l view of a three-gap spark'pluglmade in accordance with another embodiment of this invention;

FIG. 6- isabottom'plan view'of a two-gap spark plug made in accordance with still anotherembodiment of this invention; and

FIG. 7 is-'asfragmentary, cross sectional view taken along the line 77 o'f'FlG. 5';

DESCRIPTIONOF" PREFERREDEMBODIMENTS from the exposedtip'of the cent'ergelectrode. Thespacing between these two electrodesconstitutes the normal air gap across whichasparkisgeneratedifor igni tion of a fuel mixture. Inaccordance with-this invention, the center electrode tip is encased in a nonconductingcoatingridentifiedtby the numeral'17. Sirnilarly, all'or amajorportionofthe ground'electrode 16' is encased in a non cond'ucting:coatingddentified'by the numeral 18. The non-conducting! coatings may be formed by applying a 'ceramicpaste or'ah'igh temperature glass'over the electrodetips. In either case, the coating material is subjected 'to suitabl'e high temperature, thereby'to fusethe materialto th'e'electrodes. The two coatings are spaced apart'toform arr-air gap ('a); When a voltage of suitable magnitude is: applied to the spark plug, a'spark will jump 'from thezcenter electrode 13, through the insulatorcoatin'gi;1 7',:across the air gap (a), through the insulator coatingfilfiitand 'to the ground electrode 16. The insulator-coatings, whichmay be relatively thin,prev'ent chemical'and electrical erosion of the electrode points.

In the FIG. 2 embodiment-of theinventiomthe lower endof'the center electrode20 isencasedin-the-conical portion 15 of the insulating: core of .the spark plug and the ground electrode 21 is covered with a nonconducting coating.2-2. The-air-gap 'tb") "constitutes the spark gap 'for ignition of th'e fuel mixturei A double-gap sparkplug is shown in FIGS. 3 and 4-. Here, the conical core portion 15 has two, cylindrical projections 24 and Z-S'eXtendingtherefi'om; The lower portion of the center electrode 26-is offsetwith 'atip 27 encased within the projection-24l Th'e-neutral'electrode comprises a metalpiece 28 encased withinthe'projection 25. The ground electrode 29 is'encased -in a nonconducting-coating 30. When the plug is'fired, two

sparks, in series, jump across the air gaps (c) and (d).

A triple-gap spark plug made in accordance with this invention is shown in FIG. 5. In this arrangement, the conical portion 15, of the core 10, has a helical groove 32 formed in the peripheral surface thereof. A first, generally-helical neutral electrode 33 is positioned in the helical groove and has a tip 34 spaced from the tip 35 of the center electrode, said tips 34 and 35 being encased within non-conducting coating 36 and 37, respectively. A second neutral electrode 38 is positioned in the helical groove. One end of the neutral electrode 38 is spaced from the end of the neutral electrode 33, and the other end of the neutral electrode 38 is spaced from the ground electrode 39 welded to the threaded portion 12 of the spark plug case. The portions of the neutral electrodes 33 and 38 which are disposed in the helical groove are covered with a ceramic paste as indicated by the reference numerals 40 and 41, which paste is then heat cured and maintains these electrodes in fixed position on the supporting core. portion 15. It will be noted that the ceramic paste extends somewhat beyond the proximate ends of the two neutral electrodes. More specifically, these proximate ends of the neutral electrodes are completely encased with the ceramic but the ceramic is parted to form the air gap (e). That end of the neutral electrode 38 which is proximate to the ground electrode 39 also is completely encased in the ceramic. When a firing voltage is applied to the spark plug, three sparks, in series, will jump across the air gaps (f), (e) and (g).

FIGS. 6 and 7 show a two-gap spark plug made in accordance with another embodiment of this invention. A neutral electrode 43 is imbedded in a tubular member 44 made of a ceramic or a high temperature glass, said member 44 including a radially-extending leg 45 which is cemented in a diametrical slot formed in the end of the core 46. The center electrode 47 has a tip 48 extending toward the neutral electrode, which tip is encased within a non-conducting coating 49. The ground electrode 50 is welded to the threaded portion 12 of the spark plug shell and has a tip spaced from the neutral electrode, said tip being encased in a nonconducting coating 51. in this particular construction, the two spark gaps (h) and (i) are well spaced from each other. Also, the spark gaps lie on opposite sides of the tubular member 44 which serves as a combustion deflector. When the spark plug is installed on an internal combusion engine, initial ignition of the compressed fuel mixture takes place at the spark gap (h).

Although measured in milliseconds, some period of time is required for combustion to take place in those areas of the fuel mixture which are remote from the point of initial ignition. The spacing of the spark gaps and the action of the deflector provide a sufficient time delay so that an ignitable fuel mixture is present at the spark gap (1) when the second spark occurs across such gap. The net result is a more complete combustion of the fuel which provides increased power to the piston of the engine with a corresponding reduction in pollutants exhausted into the atmosphere.

The coating of the electrode tips with a high tempe rature non-conducting material eliminates chemical and electrical erosion of the tipsQwhereby the electrodes may be made of an inexpensive base metal. Also, accumulated carbon deposits on the non-conductor surfaces can be removed easily and does not necessitate a re-adjustment of the effective spark gap length, as is the case when the eroded surface is removed from the tips of conventional electrodes.

Having now described the invention what I desire to protect by letters patent is set forth in the following claims:

l. A spark plug comprising,

a. a core of insulating material carried by a metal shell,

b. a main electrode carried by said core,

c. a ground electrode connected to said shell and having an end portion spaced from an end portion of the main electrode d. a non-conducting ceramic material covering the said end portion of the ground electrode, and

e. a non-conducting ceramic material covering the said end portion of the main electrode and spaced from the covering on the end portion of the ground electrode.

2. A spark plug as recited in claim 1, wherein the said non-conducting material is a high temperature glass.

Claims (2)

1. A spark plug comprising, a. a core of insulating material carried by a metal shell, b. a main electrode carried by said core, c. a ground electrode connected to said shell and having an end portion spaced from an end portion of the main electrode to form a spark gap d. a non-conducting ceramic material covering the said end portion of the ground electrode, and e. a non-conducting ceramic material covering the said end portion of the main electrode and spaced from the covering on the end portion of the ground electrode.

2. A spark plug as recited in claim 1, wherein the said non-conducting material is A high temperature glass.

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