US1406810A - Spark plug - Google Patents

Description

J. M. ATWATER.

SPARK PLUG.

-APPLlCATl0N FILED APR. 29, 1920.

Patented Feb. 14, 1922.

L/i I u sp ark STATES- PATENT OFF-ICE.

30111? M. ,ATWATER, OF CHICAGO, ILLINOIS.

SPARK JPLUG.

Specification of Letters Patent.

Patented Feb. 14, 1922.

application filed-April 29, 1920. Serial No. 377,668.

the constantly changing character thereof,

its reluctance to vaporizing, and for many other reasons is called upon to perform heroic service in order to function properly,

.nd regulerly. It is an acknowledged fact hetrarely, if ever, do spark plugs function at their best for any length of time. Even when initially inserted, the average spark plug functions so poorly-as to be accountable, in a large measure, for the pobrfuel economy-end low engine eliiciency, so often obtaining.

It is an object of my inventionto provide plug; construction which, in operation, shell pro iuce e spark better adapted to ignite the fuel in an internel combustion engine, and which shall function regularly and coi'isistcntly in such manner.

1ft else an object of my invention to proulug construction which, in ion, s produce a spark of great th, thus enehling it to function propnder sue! adverse conditions as are de-r provided with fuel that is d'iflicult ute, and under numerous other conditions inin'iiczil to the proper functioning of a. spark plug: as heretofore constructed.

Another object of my invention is to pro vide a spark plugconstruction which when once conditioned in n predetermined manner .alilapted to ensure the best results shall maintain. this desired status against the innumersble conditions tending to destroy or alter this predete mined ind desired status.

Again provide be u s ii-l plug" construction which bination of the named objects, together with others that will I appear hereinafter, are

- with in on oil saturated cylinder, in it object of my invention to be necessary to produce a condition adapted to ensure the best functioning with a. predetermined engine and its complen'ientary electrical system, or as'may be necessary after a. long period of use.

Other objects of my invention are to provide a spur: plug construction that can be manufactured and assembled quickly, and at low cost, and which shall be of a. form conveniently adapted for use in standard internal combustion engines.

My invention consists generally in the form, arrangement, construction and compzirts whereby the above attainable; and my lnvention will be more readily understood by reference to the accompanying drawings which illustrate the preferred embodiment thereof.

In said drawings:

Fig. 1, is a central sectional view of a spark plug construction embodying my invention; and

l ig. 2, is a view of certain of the parts thereof disassembled, but arranged in the order of assembly.

The shape, form, and configuration of the spark plug parts may var I through a wide range and the particular form and arrangement shown in the drawings should, therefore, be considered as by way of illustration and not by way of limitation.

Referring now to Fig. 1, 2 is a metallic shell provided with screw threads 3 so that it may be screwed to the engine cylimler inwell-known manner.

lain insulator which shell 2, in the present instance, being held against H, gas-tight packing washer 5. by means of a threaded bushing 6, which open ates against a seat washer 7 which, in turn, engages the shoulder 9 of the porcelain insulator. 10, is the side electrode which is permanently allixed to the metallic shell 2. There is no particular novelty in the ports thus far described other than the porcelain part 4, and they have been shown only for the purpose of better illustrating the manner iniwhich the partsconstituting the invention function.- I

4-, represents at porcels positioned in the all The porcelain element 4, as here shown, is provided with a long lower central opening 11, which merges with a larger opening 12, and which, in turn, merges into a still larger opening '13 that extends to the top 14.- of the porcelain element. The openings 11 and 12, as here shown, are of smooth cylindrical form whereas ,the opening 13 is provided with screw threads 13. 15 represents what 1 term the lower central electrode and it is preferably cylindrical in form and of a size slightly smaller than the opening 11, thus providing an annular intervening space 16. To the upper end or" the lower central electrode 15 I permanently secure a member 17 which member will hereinafter be termed a shell. The lower central electrode 15 is preferably formed of a hard tough metal such as a nickel manganese alloy whereas I prefer to form the shelLot a relatively soft metal such as brass. have, by expel-L mentation and research, learned that it is essential to the functioning of the device that the union between the shell and the lower central electrode shall be a gas-tight union. it is also essential. that the parts shall be accurately aligned in order that the proper positioning of the lower central electrode shall take place and its desired spaced relation to the wall of the porcelain insulator be assured. To thesecnds, I prefer to reduce the upper end otjhe electrode 1:). as indi catcd at 12), thus providing a seat 90 against which the element 17 can be forced. The lower part/of the shell 17, in turn, is provided with a central opening 18 of considerable length. The relative sizcs of the opening 17 and the upper reduced portion 19 of the electrode l5 are such that the shell 17 can be shrunk upon the reduced port-ion 19, as indicated. Thus a nice aligmncnt ot' the parts is sccurcd and a gas-tight joint etl'ected. last it be thought thatcxpansion of the parts, due to the temperature conditions prevailing in usc, would cause this joint to leak, I wish to state that the electrode 15 projecting as it does into the zone of the most intense heat is raised to a considcrable higher temperature than that of the shell 17 so that the conditions met with in use not only tend not to destroy the gastight joint, but they actually result in the tightening of this joint, due to the grcatcr expansion of the electrode portion 19. The upper portion of the shell 17 is provided with a, chamber 20 and into this chamber depends what I term the upper central electrode 21 extending into close proximity to the upper end of the lower electrode 15 thus providing a small gap 22.

Due to different conditions prcvailingin difi'erent internal con'ibustion engines or inthe same internal combustion engine because of the changing character of the electrical ignition system, as well as changing con- -and bv turnin (litions which take place because of ordinary wear and tear, I find it desirable to provide means for adjusting the spaced relationof the upper and lower electrodes, 1. e. toprovide means for varying the size of the gap, 22. To this end, 1 thread the upper part of the upper electrode, 21, as indicated at 23, and mount it. in the internally threaded bushing 2-4;. Thus by turning the electrode, 21, in one direction the gap can be increased g it in the opposite direction can be decreased.

For the purpose of securely locking the upper electrode in place, I provide a lock nut The bushing 24: is likewise externally threaded as indicated at 26 for coaction with the threads 13 of the porcelain opening- 13. By this means the upper electrode assembly, i. e. electrode proper .21, bushing Zl and the parts carried thereby, can be screwed into the porcelain element 4.

It is a purpose at iny'inyention to establish and maintainin'tho chamber 20 of the shell 17 a predetermined conditioner status. It is not necessary to detail the precise character or status to be maintained in the space 20, but sutlice it to say that having determined upon the condition which will lend the bestresults, I desire to maintain that condition or status against alteration or va riation. I might state generally that the function of the spaced relation of the upper and lower electrodes forming the-gap 22 is to increase the voltage of the spark that will jump'the gap 27 formed between the lower cnds oi the lower central electrode and the side electrode. At the same time, in building up this'voltage condition extreme care must be cxerciscd to avoid imposing upon other parts of the electric or ignition of an internal combustion engine of forces that would destroy or injure them. Thus, for example in a modern automobile ignition system care must be taken to avoid puncturing the com-lcnser and where a coil is used to avoid injuring the coil.

()n the other hand, it the desired results are to be attained the voltage conditions nee cssary are relatively high. Thus it becomes an important matter, indeed, after having determined that condition which is sutlicient on one hand to secure the desired spark at the gap 27 and to avoid injuring other parts of the ignition system, to maintain that pre dctcrmined desired condition or status. Que oi the most necessary precautions to this end is that of avoiding the seepage of the dead gas from thecngine cylinder up throu 'h the spark plug and into the chamber 20. it has been the commonpractise to secure the cen tral clcctrodc in place by means of cement and while such cement is presumed to be impclvious to the passage of gases therethrough, in practise, it is found to be porous 'to a certain extent, and, in fact, to an extent 'sulator surrounding said such that unless other means he provided would permit seepage of gas into the space surrounding the gap .22 and hence after a time destroy, alter or modify tl'iat de sired condition initially set up in that space. I prevent the possibility of the occurrence of such a result by the provision of ashell 17 which, as already described, is united to the electrode in such a manner as absolutely to insure a gas-tight joint, under all conditions. The upper end of the shell 17 is open and is provided with an outwardly extending flange portion 28 which rests upon a seat 29 provided in the porcelain insulator. For the purpose of closing the open end of the shell 17, I provide an insulator plug 30. This insulator plug is very tightly pressed against the top of the shell 17 by means of the threaded bushing 26, i. e. as the threaded bushing 26 is screwed into the porcelain insulator it forces the insulator plug 30, very tightly against the shell.

In assembling the device the shell 17 is pressed into the opening 12 provided therefor, and being of soft character forms a fairly tight joint. The gases from the engine cannot possibly find their way into the chamber 20. In the first place, any gases attempting to escape upwardly must pass around innumerable turns or corners which in themselves should batlle the progress of such gases. If it were possible for gases to find their way upwardly to the point above the shell 17, they would be unable to find their way into the chamber 20, for the reason that the insulator plug 30 is very tightly clamped between the bushing 2% and the upper flanged end of the shell 17. The me chanical seal thus provided is admirably adapted to the maintenance of the predetermined condition or status in the chamber 20, and at the same time the arrangement is such that if desired relative adjustment of the upper and lower central electrodes can be very readily and conveniently made.

I claim l. A spark plug construction embodying therein an insulator element, upper and lower electrodes arranged therein and posi tioncd to form a gap therebctwcen, an impervious metallic shell positioned in said ingap and lorming a chamber adapted to exclude gases inimical to the condition desired in th space surrounding said gap, and mcans insulating said upper and lower electrodes one fronrthc other.

2. spark plug construction embodying therein an insulator clement, upper and lower clcctrodcs arranged therein and positioncd to. l'orm a gap therelmtwcen, an impclvious shell, formed of metal of softer character than that of the lower electrode, positioned in said insulator, surrounding said gap, and forming a chamber adapted to exclude gases inimical to the condition desired in the, space surrounding said gap, and m *ans insulating said upper and lower electrodes one from the other. I

3. A spark plug construction embodying therein an insulator element, upper and lower electrodes arr: iged therein and positioned to form a gap therebetween, a metallic shell initially having openings at both ends, said shell being shrunk upon the lower central electrode thereby closing one opening, and an insulator plug pressed against the other end of said shell and closing the other opening, thereby forming a chamber surrounding said gap, said chamber being impervious'to gases inimical to the condition desired in-the space surrounding said gap.

-l. A. spark plug construction embodying therein lower electrodes arranged therein and positioned to form a gap therebetween, a metallic shell initially having openings at both ends, said shell being shrunk upon the lower central elect-rode thereby closing one opening, and an insulator plug pressed against the other end of said shell and closing the other opening thereby forming a chamber surrounding said gap, said chamber being impervious to gases inimical to the condition desired in the space surrounding said gap, and a screw threaded element for torcing said insulator plug against said shell.

5. A spark plug construction embodying therein an insulator element, upper and lower electrodes arranged therein and positioncd to form a gap thercbetween, a me.- tallic shell initially having openings at both.- ends. said shell being shrunk upon the lower central electrode thereby closing one opening. and an insulator plug pressed against the other end of said shell and closing that opening thereby forming achamber surrounding said gap, said chamber being impervious to gases inimical to the condition desired in the space surrounding said gap, a screw threaded element for forcing said insulator plug against said shell, said screw threaded element being internally threaded and the upper end of said upper central clcctrodc being cxtcrnally threaded, whereby the position of said upper electrode, in said bushing can be adjusted.

o. spark plug construction embodying lhcrcin an insulator clement, upper and lower electrodes arranged therein and posilioncd to lornr a gap therebetwcen, a metallic shcll initially having openings at both ends, said shell being shrunk upon the lower central electrode thereby closing one opening. and an insulator plug pressed against the other end of said shell and closing the other opening, thereby forming a chamber surrouiuling said gap, said chamber being impervious to gases inimical to the condian insulator element, upper and tion desired in the space surrounding said gap, a screw tln'emiled. element for forcing Said lnsulahjn' plug against said shell, said screw threaded element being internally tln'ezutleclfl and the, upper end of said upper central electrode being externally threaded whereby the position of said upper electrode in said bushing can be adjusted, end means for locking said upper central elecfrode in adjusted position. 10

In testimony whereof, I have hereunto set my hand, this 22nd. day of April, A. D.

JGHN M. ATWATER.

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