US2226414A

US2226414A - Spark plug

Info

Publication number: US2226414A
Application number: US295266A
Authority: US
Inventors: Kapp Fred
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-09-16
Filing date: 1939-09-16
Publication date: 1940-12-24
Anticipated expiration: 1957-12-24

Description

DBC. 24, 1940. F, KAPP 2,226,414

SPARK PLUG Filed Sept. 16, 1939 v INVENTOR.

FRED K PP ATTO Patented Dec. 24, 1940 UNITED sTATEs PATENT OFFICE 3 Claims.

This invention relates to improvements in spark plugs for internal combustion engines of the type having a central electrode which extends through a passage provided in a porcelain or equivalent ceramic material insulator, which insulator is secured in place within a metallic outer shell or casing having a second electrode arranged in sparking relation to the inner end of said central electrode, and the principal object of the invention is toprovide certain improvements in and relating to the central electrode structure and its relation to the insulating member, whereby there is provided a spark plug which, after severe use, will remain gas-tight and will fire at high working pressures in modern high compression automobiles, trucks, tractors, and other types of motors at every ignition cycle.

A further object of the invention is to produce the hottest possible spark and, at the same time, .gsuring a perfect combustion in the iiring chamr. A further object of theinvention is to provide an insulated central electrode equipped with three compression seals, thus forming a gastight spark plug insulator.

An additional object of the invention is to provide a spark plug having a V-type ground and a central electrode, said V-type ground providing two top spark surfaces wherein the spark functions to heat ilrst, said central electrode serving to split the supplied spark for two parellei channels, thus keeping the spark alive longer and producing a hotter spark for better combustion.

of this speciilcation and in which like numeralsare employed to designate like mrts throughout the Same,

iiexible cemented arresting ring and the short flattened one-half turn twisted. knurled and grooved portion of the central electrode;

Fig. 3 is a horizontal section through the ring, the view being taken on the line 3-3 of Fig. 1;

ywhole the grounded or shell electrode.

. Fig. 4 is a similar sectional view taken on the line 4 4 of Fig. 1; andv Fig. 5 is a plan view of the asbestos ring that forms part 'of my invention.

In the accompanying drawing wherein for the 5 purpose of illustration is shown a preferred embodiment of my invention, the numeral 1 designates a hollow metallic vshell or casing of a spark plug adapted to receive therein an insulated core 8. the detailed construction of which lil will be hereinafter described. The said casing has its lower portion externally threaded as at 9 to engage an opening in the cylinder of an internal combustion engine, while its upper portion is formed with an angular head I0, whichl can be engaged by a wrench for attaching the plug in place. The numeral il indicates a gland nut that has threaded connection withinternal threads i2 oi the angular head I0 of the spark plug casing. The said nut serves to retain in 20 place the insulated core 8 after it has been fitted in the hollow casing l.

Extending through the bore i3 of the insulated core is the primary or central electrode, designated as a whole by the reference character A, 25 while the referencecharacter B designates as a As illustrated tol advantage in Fig. i, it will be noted that the upper end of'the electrode is threaded as at it and receives thereon -a nut i5 utilized in 3G fastening it to one oi the current wires of the ignition system. Integrally formed with the centrai electrode is a flange i8 and an enlarged head l1, the latter adapted to be received in the en- 'larged bore II of the core, while interposed be- 35 tween said flange and the upper end I8 of the insulated core is a pair of gaskets-one of aluminum, as indicated by the numeral I9, and the other of asbestos material, as indicated by the numeral 20. In my years of practical experience with spark plugs, I have-"found, by examining old and new plugs to ascertain the reason for failure, that the main reason for loss of edectiveness has been the `absence oi' a proper compression seal around 45 the'central electrode, whereby the heat escaped outside o the central electrode through the top seal gasket and the upper insulated opening, thus causing'a loosening of the cement which is applied on the plain central electrode surface, which loosening action has been occasioned by the escaping compression and heat.4 Accordingly, the

' .cement has'lost its binding strength when it has become too hot.

It is for this reason that I have eiiected the assembly of the aluminum gasket .I9 and the asbestos gasket 20; and by virtue of the construction employed, the asbestos gasket is pressed to the top of the insulated opening by the alu- 5 mlnum gasket i9, and an effective compression seal is realized.

Spaced from the head il and secured to the central electrode A is a small flexible ring 2l that is preferably fastened throughthe center l of the shaft of the electrode and wound around one complete turn. This ring functions to hold the cement 22 while the latter is soft and when assembled to the insulator body, the ring acts as a stop for the cement. Accordingly, when the l cement has become hard and dry, a gas-tight safety seal is assured, which, to my knowledge, does not exist in any other type of spark plug.

Formed on the shaft of the electrode is a knurled member 23 that is of a substantially fiat one-half turn twisted form, provided with a knurled surface as at 2l and barbs as at 25, which member 23: retains the cement absolutely tight on its roughened surfaces and the inner insulator wall and presents, when subjected to a 25 light twist, a vibration on its upper end. It will be observed, at the same time, that even if .the top terminal is broken on', there is still assured a gas-tight compression seal, and the spark plug will continue to fire as long as the damaged part makes the contact with the remaining part of the central electrode in the spark plug insulator.

As disclosed to advantage in Fig. 1, the numeral 2B indicates the threaded portion of the central electrode A that is threadedly secured to l the lower insulator shoulder of the spark plug insulator. The numeral 21 indicates a gland nut gasket interposed between the lower end of the gland nut and the annular upper outer shoulder 28 of the casing 1, while the numeral 29 indicates the plug seat or shoulder on which is positioned a sealing and cooling gasket 30.

I wish to herewith supplement the features of construction of the plug, as above described, with a statement of facts relative to the reason for devising said construction.

'I'he plain electrode system does not carry enough binding cement to produce the desired effect around its axis, and, therefore, when subjected to higher temperature and severe service,

will loosen up, even on some new spark plugs. Most of the engines manufactured have increased compression pressures, but the fact remains that spark plug failures, mainly, current leakage under high working pressures, have not been brought under satisfactory control. The provision made in this invention will eliminate central electrode overheating and current and compression leakage through the medium of the spark plug central electrode around the spark plug insulator,

e0 thus resulting in longer plug life.

It is a well-known fact that spark plugs that leak compression and current become hotter. The said leakage throws the plug out of its proper heat range, and the electrode under' these conditions deteriorates faster, swells up in diameter, and `causes insulator firing tip breakage that sometimes results in costly engine wear and loss of power.

Mechanical characteristics of a spark plug vary with the type of motor and service conditions in which they are used. While a spark plug insulator may show satisfactory results under a cool test, nevertheless, it is liable to leak when hot under compression. Coolcompression tests are i not sufficient. The leakage for a new spark plug shall not exceed a iixed'maximum. The resistance path from the central electrode to the metal body of a spark plug shall not be less than a predetermined minimum. My particular plug conforms in every respect to the Federal specifica- 5 tion for spark plugs.

I wish to further point out that plain central electrodes in the liquid cement, when subjected to heat and severe conditions, do not give enough binding strength to maintain a safe compression l0 seal. I have, accordingly, proposed in the present invention to produce a gas-tight spark plug central electrode wherein asafe compression seal will be maintained.

The most serious trouble in all spark plugs is 15 spark plug leakage; and, accordingly, the'rst gas-tight compression seal in a spark plug should be provided as close as possible to the spark plug insulator lower shell seat and shell inside the gasket for faster dissipation of the heat from the 20 central electrode and insulator firing tip. This I have accomplished by the provision of the sealing and cooling gasket 30.

Likewise, in the present invention the danger of the loosening 'of the cement binding that 25 causes plug overheating is reduced to a minimum, fast electrode deterioration is eliminated, and every effort has 'been expended to produce a plug, by the construction employed, that will not be thrown out of balance, and loss of power and 30 poor motor performance will not be experienced.

I have, accordingly, provided a new spark plug central electrode with three gas-tight compression safety seal features, which plug is economical to manufacture, and wherein outside moisture is 35 prevented from reaching the operative parts of the spark plug. Further, the new flexible wire cement stopper positioned around the upper central electrode shaft serves to hold the cement While soft and when assembled to the insulator body safe in its proper intended second compression safety sealing place, and, accordingly, when dry and hard, a gas-tight second compression safety seal is assured, which, to my knowledge, is not found in any other spark plug.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and that various changes relative to `the material, size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention orthe scope of the subjoined claims.

Having thus described my invention, I claim:

1. In a spark plug equipped with a metallic housing having a ground electrode provided therein and an insulating member positioned within said housing, of a central electrode having a portion thereof threadedly secured within said insulating member, means carried by said electrode adapted to cooperate with cement positioned within said insulator to effect a compression seal, said means comprising a ring carried by said central electrode, and a distorted member formed integral with saidl electrode and having a barbed and lserrated surface, said central 65 electrode being threaded throughout a portion of its length.

2. In a spark plug equipped with a metallic housing having a ground electrode provided therein and an insulating member positioned in said go housing, of a central electrode having a portion thereof threadedly secured within said insulating member, means carried by said electrode adapted to cooperate with cement positioned within said insulating member to eil'ect a compression seal, f

sulating xnember, the cooperating threads providing a primary compression seal, and means formed integral with said central electrode including a distorted barbed portion capable of cooperating with cement positioned within said insulator and adhering to said distorted barbed portion to effect a supplemental compression seal.

FRED KAPP.