US1570320A - Spark plug and method of making same - Google Patents

Description

Patented Jan. 19, 1926.

UNITED STATES.

ALBERT E. SEREWICZ,

0F CHICAGO, ILLINOIS.

SPARK PLU'G. AND METHOD OF MAKING- SAME.

Application le October 27, 1919. Serial No. 333,751.

To all whom t may concern.'

' Be it known that I, ALBERT E/SEREWICZ, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Spark Plugs and Methods of Making Same, of which the following is a specification.

. This invention relates to spark plugs such as are used in internal combustion engines, and a method of making them, and among the objects of my invention are to' so improve upon the structure as to reduce the possibility of. short circuit; .to reduce the possibility of breaking the insulation; to produce a new plug and a corresponding new method Y`of manufacture; to improve upon the construction of spark plugs in general l; and to secure such further and incidental objects and advantages as will later more fully appear.

In most prior spark plugs, the insulator, passing through 'the shell by which the plug is mounted in the engine, extends above the top of the shell and is therefore exposed in such a manner that it is easily broken accidentally. Furthermore, it is exposed to cold drafts of air and to accidental splashing of water, as when it is necessaryto raise the hood out of doors during a rain, and it is therefore likely to be cracked from one of these causes. Also, with the electrode projecting above the top of the insulator, one is likely to vget shocks'by accidentally touching the electrode, and this is obviated by having this part terminate within a hollow in the end of the insulator so that it is impossible to touch the electrode when the same is live, except by using some tool and making a definite purposeful effort to do it. It has been common, though not universal practice, to secure the insulatonwithin the shell by means of a detachable ring y or gland engaging screw threads iny or on the shell. The cutting of the threads on the shell and Aring or gland is ex uensive, and furthermore, insulators are lo ten cracked by the glands being screwed in too tightly. I have obviatedthis by my new method of manufacture. v

When the `firing point, usually connected to the shell, is ut lnto a'hole drilled longitudinallyinto t e e'ndJof the .shell and then bent Vover into proximityc to the central electrode, an entirely .Separate Operation is involved in the drilling of the hole in the shell, it being necessary to remove the shell from the machine in which the threads are cut and put it into another, in which thc hole is drilled. This I have obviated by drilling the hole transversely through the edge of the shell, which can bedone while the shell is being held stationary in the machine in which the threads are cut.

In the accompanying drawing, showing my invention, Fig., l is a longitudinal section of a completed plug provided with a central y electrode adapted to receive any ordinary snap connector.

Fig. 2 is a longitudinal section of a completed shell before the insulator has been applied, and 1Eig. 3 shows a plug, partly in elevation and partly in longitudinal section, provided with a central electrode having its external end screw-threaded for attachment of a screw-threaded connector.

Referring more in detail to the drawing, in which'A represents the shell, B the insulator, C the central electrode, and D the connector adapted to engage ythe external end of the electrode, 1 represents the wrench. Harige of. the shell A, and 2 the screw-threaded end, common in structures of this character. 3 is a shoulder formed within the shell, against which rests any suitable gasket 4 to cushion the insulator and form a tight joint between the shell and the insulator. 5 is a iange on the insulator B adapted to press against the gasket l and to be engaged by an inwardly flexed art 6 of the shell A, the upper and lower aces of this flange being preferably inclined outwardly, although this is not necessary.

The insulator B is made hollow at its outer end, as shownat 7, and within this hollow, preferably near its inner end, is the end 8 of the central electrode C, the shaft of which is molded in to the body of the insulator so that it is held rmly therein, and leaves no opportunity for the escape of gases between'the-.electrode and the insulator. As shown in Fi 1, this end 8 is provided with a ball whic may be engaged by av spring connecten', This terminal or outer end 8 may be made in various forms to adapt it for use with any of the several standard forms of connector. It is shown in Fig. 3 that this end, instead of having a ball, may be screw-threaded and therelos ufacture is very useful lmore, since there is a flange and the end of fore may have a screw-threaded connector secured thereto, as shown at 10. In the latter case,'the conductor 11 Y asses down through a hollow in an insulating member, and has it inner end spread out so that when the connector D, carrying the sleeve lO, is screwed into place, intimate contact will be caused between the end of the conductor 11 and the end of electrode C.

It will be observed in Fig. 2 that shell A is provided with a cylindrical opening in its outer end, and that flange 9 1s connected with the body of the shell by a comaratively thin wall 6, so that when the insulator B is put into the shell and the latter; is compressed longitudinally, the wall 6 will yield inwardl and press tightly against the flange 5 o the insulator, thereby pressing it tightly against thev gasket 4, and preventing an leakage of gas between these parts. It wil also be observed) that 1n this method of manufacture, a space is left between the upper end of the insulator and the flange 9, forming the top of the plug. The groove in the outer wall of the plug is turned in such a manner as to cause the wall to flex inwardly when compressed longitudinally and flex most sharply at the ower part, the same being progressivelyv 4thickened from'the thinnest portion below to the full thickness of the flange above. In this Way a sort of metal cushion is formed whereby undue pressure caused by the press on the insulator during the assembling operation, is avoided. The flange 9, being longer than the insulator, allows a. machine to be used to compress the shell longitudinally without danger of fracturing the insulator, thereby causing a very tight fit between the insulator and its cooperating parts. This flange 9 also prevents cold air currents from striking the insulator as well as preventing water from splashing thereon from any side. Furtherace between the lie insulator, this space will serve as an air jacket for the protection of the insulator.

During the Iprocess of manufacturing the shell, a hole 13 is drilled through the in- -ner end thereof and a pin or firing point may be inserted in this vhole to extend aV suitable distance inwardly toward the eentral electrode C. After this pin 14 has been inserted, the metal of the shell is indented sulliciently to cause the in to be firmly held in place. This meth of man since it permits the drilling of the hole in the shell to be' done while the shell is held in the-machine by which the .thread is formed thereon without the necessity of an extra operation, which operation, it has been (found in practice, re-Y sults inthe breaking of numerous Vdrills because the parts are not properly held.

'As pointed out above, several advantages are secured by providing the flange 9, which extends outwardly far enough when the spark plug is completed so lthat the outer end of the insulator is entirely protected from external blows and forces. It is also a considerable advantage to have the outer end of the electrode terminating well within the outer end of the insulator and sleeve so that not only is short circuiting prevented, but. no blows can reach this electrede accidentally, thereby cracking the insulator, as is so common in cases where the electrode projects considerably beyond the end of the insulator.

It is believed that the construction and operation of my device will be obvious from the foregoing without more detailed explanation, and it is of course understood that the specific description of the structure and Alncthods set forth above may be departed from without departing from the spirit of my inventiop as set forth in this specification and the appended claims.

Having now described my invention, l claim:

l. A spark plug comprising longitudi` nally apcrtured body and flanged portions, an insulator` therein and having a flange, said body portion having a shoulder for the flange of the insulator, said body and flange portions being connected by a part which is thinner than the flange, said part`r flange connected to the said inwardly bent portion and extending outwardly beyond the end of the insulator.

A spark plug having a longitudinally apertured shell provided intermediate its ends with a shoulder, a flanged insulator .pressing against said shoulder, the said shell having a flange connected to the body thereof by a relatively thin portion flexed inwardly to press against the flange of thel insulator, thereby holding the sarle in position, said insulator having a hollow outer end terminating within the outer end of the flange and separated therefrom by an air 4. A spark plug-having a longitudinally apertured shell'provided intermediate its ends with a shoulder, ,a5 flanged insulator pressing against said shoulder, the said shell having a iange connected to the body thereof by a relatively thin portion flexed i -body portion having an internal shoulder,

inwardly to press against the flange of the insulator, thereby holding the same in position, said insulator having a hollow outer end terminating within the outer end of the flange on the shell, and separated therefrom by an air space, said insulator being providedhwith av longitudinally disposed electrode terminating inwardly near the inner extremity of the shell and terminating outwardlywithin the hollow in the end of the said insulator.

5. The method of making a spark plug i comprising forming an apertured shell with aflexible portion intermediate the ends of the shell which portion is thinnerthan the iange', placing a flanged insulator in'said shell with the flange of the insulator seated upon a shoulder formed in the shell, longitudinally compressing the shell to cause an inward flexing of the intermediate rela-V 'shoulder for the flange of the insulator.

6. A spark plug comprising an apertured an insulator located in said body portion and seated on saidshoulder, an apertured ianged portion connected to said body portion by a flexible portion which is thinner than the flange, said flexible connecting por.- tion extending inwardly into contact with insulator for forming a second shoulder therefor.

7 A spark plug comprising a shell, an insulator mounted in the shell and having its outer end terminating Within the outer end of the shell, said shell having a thin Wall portion intermediate the ends of the shell and capablewhen the shell is longitudinally compressed to flex into tight en-l gagement with the insulator.

In wit-ness whereof; I hereunto subscribe my name to this specification.

ALBERT E. SEREWICZ.

Images