US2286515A

US2286515A - Spark plug and method of making the same

Info

Publication number: US2286515A
Application number: US356240A
Authority: US
Inventors: Semon H Stupakoff
Original assignee: SPARK KING CORP
Current assignee: SPARK KING Corp
Priority date: 1940-09-11
Filing date: 1940-09-11
Publication date: 1942-06-16
Anticipated expiration: 1959-06-16

Description

` June 16, l942 s. H. sTuPAKol-'F SPARK PLUG AND METHOD yOF MAKING THE SAME -Filed sept. 11, 1940 Z6 J4 33 )l gemela J7. S'upakoff jup ATTORNEY- l INVENTOR y making of the od is the use in special relationto the glass, of al metal or alloy whose coeilicient of thermal ex.

Patented June is, i942 Semon Il. Stupako, Pittsburgh, Pa., assigner to The Spark'liing Comration, New

York, N. Y.,

a corporation of Delaware Application September 11, v194:0, Serial No. 356,240 18 Claims.' (Cl. 123169) tion pertains is that wherein an electrode-carry-4 ing main outer metal body or jacket and through which is extended the central electrode, is separated from the latter by an insulator made of a material, such as glass, which has a coemcient of thermal vexpansion lower than the metal of which the jacket is made.

In U. S. patent to me No. 2,103,759, there is disclosed a method of employing a material like glass, instead of porcelain or the like, for the insulator.l A feature of said methpanslon can be matched to glass, such, for instance, as the' alloy Kovar. As explained in my U. 8. Patent No. 2,103,759 Kovar is an alloy of the type disclosed in U. S. Patent No. 1,942,260, and this alloy is commercially available under the trade-mark Kovan The use of a material like glass for the insulator but in a different way than as explained in said patent, and of a metal or alloy like Kovar substantially according t'o. the teachings of said patent so far as is concerned the useful functioning of said metaivwhen encircled by glass and when interpody between the jacket and glass, is the basis of the present invention. (Hereinafter, for brevity, Kovar merely will be mentioned and claimed, but then as inclusive of Kovar or the like, that is. of any metal or alloy having a coefficient of thermal expansion which can be matched to glass; likewise for brevity, glass. merely will be mentioned and claimed, but then as inclusive of any suitable transparent material. A transparent material for the insulator is highly desirable,

- for the reason that when the insulator is transparent one can determine by the light which diffuses upwardly through the insulator just how the cylinder is firing without removing the plus from the engine.)

In the-particularway described in detail in said patent as the then recommended procedure in carrying out the method forming the subjectmatter thereof, the glass insulator is a preformed tubular one, and the auxiliary member, made of Kovar, is of ring form'. l In carrying out the present invention, a Kovar member in this form is still preferred; but the insulator is a solid mass 'of glassy cast in situ, in the metal jacket, for instance as taught in U.- S. Patent No. 1,731,280 to Warren, and preferably thus cast after preassemand hereinafter also,

bly of the Kovar member and the jacket in such manner that at least a part of said member is extended into the interior of the jacket, so that the molten glass entered into the jacket solidiiles in part against the metal of the jacket and in part against a portion of the Kovar member in the jacket.

Thereby' the very important objects are obtained of effecting a large reduction in the cost of manufacture of a plug made in accordance with the aforesaid patent to me while retaining important advantages thereof, this because the glass insulator is cast in place in the jacket; and of providing mechanically a much sturdier plus, thisr because the insulator is a solid block of glass instead of a fragile tube.

By the present invention, as in said patent to me, the Kovar member is preferably non-.integral with the jacket and is permanently fused, as by thermal coefilcient has been successfully used, to provide not only welding, to the jacket, so as to set up a permanent gas-tight seal between vthe jacket and the Kovar member; but by the present invention the Kovar member is preferably wholly contained in the jacket when thus -joined thereto, thereby to have said member completely embedded in` the glass insulator.

In carrying out the present invention, thereby to provide a, solid glass insulator instead of a tubular one as recommended in said patent to me, a'borosilicated glass having about the same as called for by said patent a gas-tight plug but a very inexpensive and rugged one having suillciently high resistance to thermal shock and enough electrical resistance between its jacket and its central electrode to warrant its adoption in service.

^ The invention will be more clearly understood from the following description, when taken in connection with the accompanying drawing, which illustrates embodiments of the invention.y

as now preferred, but it will be understood that this drawing and description are merely by way of illustration, since the scope of protection con- I templated ls to be taken from `the claims appended.

Insaid drawing: Fig. 1 shows, in side elevation, one form of larged scale, a Kovar ring member which is in the form of an eyelet.

Fig. is a vertical sectional view, taken through a means for molding the glass insulator.

Fig. 6, partially broken away at the top, is a View similar to Fig. 3, showing a different embodiment.

Fig. 7 is a view similar to Fig. 6, showing still another embodiment.

Referring to the construction illustrated in Figs. 1 through 4, I0 designates the metal jacket, having a head portion II polygonally shaped for engagement by a wrench, and a threaded extension I2 to be entered-in a cylinder of the engine. A central electrode I4 has its main length, this length marked I5' and made of Kovar, ,encased in an insulator II which is a solid mass of glass cast in situ, so as to iill the interior of the jacket down to a point some distance above the bottom of the latter, and so as to extend up above the top of the jacket as a substantially conical extension the flat top of which lies against the underside of a disk I1 which is integral with a threaded stud I8 for taking a nut-like terminal I9. i

The central electrode I4 is shown as made up of three separate pieces, these being the said main length I5 of Kovar, an upper iitment including the disk I1 and the stud I8v of any suitable metal or alloy less expensive than 4Kovar, and a lower sparking tip 20 of any suitable metal or alloy better adapted than Kovar to constitute a sparking point. 'I'hese three pieces which here make up the central electrode are permanently joined into a unitary structure, as by welding the squared oi upper end of the part |5 to the disk I1, and the squared off lower end of' the ggrt I5 to the squared off upper end of the tip Any suitable type of electrode for sparking coaction with the central electrode can be provided, such as the one shown at 2|, projected from the inner end of the threaded extension I2 of the jacket.

The hollow within the jacket I 0, which extends from end to end thereof, is annularly flatly shouldered at 22, and on this shoulder is seated a Kovar eyelet 23.' The eyelet is positioned on the shoulder 22 so that the horizontal flange 'of the eyelet rests on said shoulder, and this frange is Welded to the shoulder. Since in the form of the invention now being described the entirety of. the eyelet will be embedded in the glass as soon as the insulator is castl in place in the jacket, welding of the horizontal flange of the eyelet to the shoulder 22 will be performed before the glass insulator is cast. The welding is continuous all around the eyelet.

Referring to Fig. 5, the jacket I0, .having welded therein the eyelet 23, is shown as held in obtained when the glassis flowed into the jacket' `of the plugin a direction such that the glass moves therein along a path causing it to be a mold including

separable parts

24 and 25, es-

tablishingA between them a cavity 26 shaped at its extreme left end to receive the disc I 1 and the stud is of the centrai electrode u. The op-L posite endof this cavity is shaped to receive a metal plug 21. To the left of the location for this plug, the cavity 28 is shaped to receive the jacket I0, and to the left of the location for the jacket, the cavity is shaped to form the conical extension of the insulator beyond the jacket. The

end of the plug 21 adjacent to the jacket is reduced in diameter to nt snugly within yet readily removably from the interior of the jacket, and the plug has an annular shoulder -28 to abut against the inner end of parts are arranged as illustrated. 'Ihis reduced end of the plug 21 has a cylindrical recess 29 for seating the sparking end of the central electrode I4. The cavity 26 furthermore is so shaped, relative to the shaping of the jacket I0, that with the mold part 24 removed, and with the plug inserted in the jacketl and the center electrode linserted in the plug, this temporary assembly of jacket, 'plug andcenter electrode can be laid in the part of the cavity 26 formed in the mold part 25 in such way as to insure maintenance of such assembly' and to settle the center electrode in the jacket coaxial with the latter and at the same time in a way to locate a round opening 30 in the jacket, normal to one of the flat faces of. its

- Wrench-taking vpart I I as indicated in Fig. 1, in 'registry with' a molten glass supply port 3| in patent is owned by the assignee hereof, who is' 'also the assignee of the aforesaid patent to-me.

The molten glass supply port 3| is at the bottom center of a molten glass feed c up 32, served by a descending" plunger 33 carrying

compression rings

34 and 35. As the parts are shown, this plunger has descended just far enough tocause a little of the molten glass tobegin entry into port 3|. Y After setting of the glass, the plug is com', pletely made; except for, preferably, the subsequent'addition of the electrode 2|, and exceptv for breaking off the stem of glass in theopening 30 where the latter protrudes beyond the exterior of the part II of the jacket, should it so protrude after opening'of the mold and removal of the plug therefrom, and except for grinding the glass. smooth and flushl with-said part II, if such inish is desired.

Referring to the form of the invention shown in Fig. 6, the plug here4 shown is inall respects similar to the plug of Fig. 3, and'is one made as describe.' in connection with Figs. 3 and 5, except that the Kovar eyelet 23 is arranged with its neck depending, instead of upstanding as in Fig. 3. The arrangement of Fig. 6 is preferred over that of Fig. 3, as eliminating or minimizing the creation of small checks in the glass, sometimes struck head-on by an edge portion of the/Kovar member, which member is usually 'onlya few thousandths of an inch thick. It is most convenient to admit the glass through aport in the' jacket at about the location ofthe port 3U of Fig. 1, so that the glass ows in the jacket toward and past the shoulder 22 and whereas in the case of Fig. 3, the molten glass thus admitted moves in a path so as to be struck head-on by the upper edge portion of the neck of the eyelet, in Fig.y6 the -molten glass thus admitted moves in a path so as to slip freely pastsaid edge por- A tion, now at the bottom of the eyelet and close the jacket when the against a cylindrical interior of the jacket below the shoulder 22.

The form of the invention shown in Fig. 7

even better attains the advantage last discussed.

Here, it will be noted, with the Kovar member still the eyelet 23, and arranged as in Fig. 6 on.

a shoulder 22' exactly like the shoulder 22 of Fig. 6, the jacket, marked, III', hasitsinterlor so shaped that a second and lower shoulder is provided, at 22, forhaving squarely abutted thereagainst the lower edge portions of the depending neck of the eyelet, and beyond'the locus of the bottom of the eyelet this shoulder 22" is laterallydownwardly curvedr into smooth merging with the cylindrical interior wall of the jacket therebelow.

In anyform of the invention. then, due to the factzthat the Kovar member welded to the jacket is thereby fused thereto annularly ofthe jacket,

and due to the fact vthat the glass cast against.

the Kovar' member is fused thereto also annularly of the jacket, a permanent gas-tight seal is provided between the jacket andthe insulator; and due to the fact that theglass likewise is fused encirclingly of a part of the central electrode made of Kovar, a permanent gas-tight seal is `at the same time provided'between the centralelectrode and the insulator-all exactly as in the aforesaid patent to me, but according to a method of manufacture which is very much less expensive than that of said 4patent and provides a mechanically strong and rugged plug.

It is to be emphasized that while I have stressed herein the advisability of preassembly of the Kovar member and the jacket, and by welding, and in such manner that by this preassembly the Kovar member is wholly or partially extended into the interior of the jacket, it is possible that further experimentation will show that satisfactory results'can be obtained when such weld-joined preassembly is dispensed with', or when the Kovar member is wholly he-v yond one end of the jacket; that is, when the molten glass is to cast to form the insulator so as to solidify partially against the jacket and partially against the Kovar member, and thereafter, with the Kovar'member .only partially inserted in the jacket or wholly beyond an end of the same, the Kovar member is permanently fused to the jacket. As in the aforesaid patent to me stated, the terms fused or fusion" are intendv vention as defined by the claims.

I claim:

1. A spark-plug comprising a metal jacket, a central electrode including a length of Kovar, a Kovar member permanently fused to the jacket, and a glass insulator c ast in the jacket and around said electrode length and against said member and fused to the two parts last mentioned by the setting of the glass. 1

2. A spark-plug comprising a metal jacket, a

central electrode including a length of Kovar, a

Kovar member of a composition different from that of the jacket and permanently fused to the jacket, and a glass insulator cast in the jacket and around said electrode length and against said member and fused to the two parts last mentioned by the setting of the glass.

3. A spark-plug comprising a metal jacket, a central electrode including a length of Kovar, a Kovar member at least partially extended into the interior of the jacket and permanently fused to the jacket, and a glass insulator cast in the against said member and fused to the two parts last mentioned by the setting of the glass.

4. A spark-plug comprising a metal jacket, a central electrode including. a length of Kovar, a Kovar member wholly in, the interior of the jacket and permanently fused to the jacket, and

a glass insulator cast in the jacket and around 5; A spark-plug comprising a metal jacket, said jacket having an interior shoulder, a Kovar member permanently fused at said shoulder to the jacket, a central electrode, including a length of Kovar, and a glass insulator cast in the jacket and around said electrode length and against said member and fused to the two parts last mentioned by the setting of the glass.l

6. A spark-plug comprising an electrode including a length of Kovar, a metal jacket open from end to end and through which the-elec.- trode passes, a Kovar member permanently fused to the jacket, and a solid glass body supporting the electrode and insulating it from the jacket, said glass body fused to said electrode length and to said member. l

7. A spark-plug comprising an electrode, including a length of Kovar, a metal jacket open from end to end and through which the electrode passes, a Kovar member having a flange, said flange permanently fused to the jacket, and a solid glass body supporting the electrode and insulating it from the jacket, said glass body fused to said electrode length and to said member.

8. A spark-plug comprising an electrode, including a length of Kovar, a metal jacket open from end to end and through which the electrode passes, a solid glass body supporting the electrode and insulating it from the jacket, the metal jacket carrying a thin flange member of Kovar, said flange member being joined to the jacket by permanent fusion of the metal of the flange member with the metal of the jacket, and said glass body being fused to said electrode length and to said member.

y 9. A spark-plug' comprising an electrode, including a length of Kovar, ,a metal jacket open from end to end and through which ythe elec-` larly shouldered, and said flange is permanently fused to the jacket at said shoulder:

v12. A spark-plug -as in claim 9, in which the jacket is internallyannularly shouldered, and

said flange is permanently fused to the jacket at said shoulder, said eyelet including a neck portion depending below said shoulder.

13. A spark-plug as in claim 9, in which intery mediate its ends the jacket has a higher internal annular shoulder and vva lower internal anljacket Aand around said electrode length and 7s nular shoulder, said eyelet including a neck portion dependent from said flange, said ange being permanently fused to the jacket at said higher shoulder and the rim portion at the bottom of said neck overlying said lower shoulder.

14. A spark-plug as in claim 9, in which the jacket is internally annularly shouldered, and said flange is permanently fused to the jacket at said shoulder, said eyelet including a portion downwardly offset from said flange, and the interior of the chamber being recessed below said shoulder to receive said downwardly Voiset portion.

15. The method of assembling a spark-plu k,which includes, as one step, casting a solid body of glass about a central electrode, including a length of Kovar, and within a metal jacket and against .a KovarA ring, so that, during the setting ofthe glass to form said body the glass is fused to said electrode length and to said ring, and, as another step, welding the Kovar ring to the jacket.

16. The method of assembling a spark-plug which includes, as one step, :casting a solid body of glass about a central electrode, including a length of-Kovar. and withina metal jacket and against a Kovar ring, so that, during the setting of the glass to form said body the glass is fused to said electrode'length and to said Iring, and,

as another step, welding the Kovar ring to the jacket before said casting step.

17. The method of claim 16, in which said ring includes a 'thin tubular portion open at both ends and through the interior o f which, the molten glass is ilowed longitudinally of the jacket during said casting, said tubular portion at one end terminating in an edge directed toward one end `of the jacket. and said ring being arranged in the jacket, relative tothe point of admission of the molten glass, so that the flowing glass approaches said edge after passing .through