US1234757A - Sparking plug. - Google Patents

Description

A. E. HEATH.

SP'ARKING PLUG.

APPLICATION mm nov. 29. |915.

Patented July 31, 1917.

f STATES ARTHUR ERNEST HEATH, 0F LQNDON, ENGLAND.

BPARKING PLUG.

Bpeeication of Letters Patent Patented July 3l 191 7.

Application led November 29, 191,8. Serial No, 134,091,

To all whom it 'may concern.'

Be it known that ARTHUR Enb'nsr HEATH, a subject of the King'of Great Britain, residin at London, England, has invented certain new and useful Improvements in. Sparking Plugs, of which the following isA a specific-ation. The object of myinvention is to construct a sparking plug for internal conibustion enines in which the central electrode is peri ectly insulated from the metal body or casing, an air space is provided within the metal body or casingr and in some cases the metal body and other parts may be provided with holes to allow of a current of air passing through the air space for keeping the central electrode cool.

, According to my invention I construct the sparkin plug from a tubular metal body forme with an enlargement or chamber at one end and asmaller chamber at the other eudand with a contraction or neck between the two, an electrode having a 'screw thread atene end and an enlargement or shoulder at the other, an insulator surrounding part of the electrode and having one vportion of larger diameter than the other or fitting the smaller chamber and obtaining a seating against the contraction or neck in the metalV body, an'air space within the larger chamber the cap and the walls of the casing surrounding same being provided or not with holes to allow of a circulation of air within the air space, a sparking point on the central electrode or on a ring hold to lthe metal body by, turningover the end, nuts engaging the central electrode for securing the cap and electrode and :the bottom insulator to the metal body, und a cup shaped insulating cap having its-tubular portion o-V sitioned within the enlargement or cham er' of the metal body and acting as an insulating apron between the metal body and the i central electrode.

My invention will be iclearly understood from the following description aided by the annexed drawings in whih:-

Figure ljista sectional elevation of a sparking plug constructed according to my invention.

Fig. '2 is a plan of same. y Fi 3 is a similar view to Fig 1 but showing e insulator held in place y the center electrode I and the` metal body and cup shaped insulator provided with means for allowing of a passage of 'air through the air space for cooling pur'roscs, and with the sparking point carried by the central electrode instead of by a washer as in Fig. 1./

Fig. Lvlis an elevation of Fig. 3,

According to my inventiond form the tubular metal body o of the plug with an enlargement or chamber b at'its top or rear end, and its bottom or front end c, which is screw threaded in the usual way for screwing the plug into the cylinder, is formed with a contraction o1 neck a in the forni of a beveled valve seating in its bore situate between the chamber b in the^enlai-ged top end o the plug andthe. borein the smaller bottom end,

The porcelain or other insulator e which surrounds or partly incloses the conductor or center electrode f, is formed of two diameters, the larger end4 of the insulator o fitting within the bore of the front end of the metal body a, to the contraction or neck' The open end of the enlarged chamber b i in the metal 'body o is closed by an insulator cup shaped cap y with its tubular portion h Iextending within the body or shell of the i' metal body a, this extension h acting as an insulating apron between the shell or metalA body a of the trede j.A

The cap y has a central hole i for the passage of the screw threaded end of the plug and the 'central elecelectrode, and the insulator cap g is secured in position at the top end of the metal body a by a nut j and washers k on the threaded end of the conductor or electrode f. The

bottom or front end of the electrode f is formed with an enlarged head Z, so that by tightening the nut y' on the electrode f the insulator e can be drawn into the bore of the metal body a and pressed firmly against the contracted seating al in a gas tight manner, l the insulator e may also be secured and held firm in the plug by means or' a washer m bearing on the outer edge, the end of the metal body a of the plug beingspun over to receive and retain the washer m and insuintox' e in place, the washer carrying the sparking point n as in Fig. 1 or I may form the sparking point on the central electrode, as in Fig. 3, in which case the washer is dispcnsed with.

g is a' nut und 1' is a spring washer encircling the cloctrodo f the nut' l] securely fixing the insulator c to the 'electrodo f.

, j* 1s u terminal nut for connecting the usual wres'to tho electrode.

By this construction of plug, the whole of the parts are misil cleaned, und the enlarged chamber b provi es an air space surrounding the end of theinsulator und a, portion of the conductor so that the heat ofthe metal body of the plug is not communicated to the relain' insulator at that part, and to u'ther insure the cooling of the electrode f. and insulator o especially when such a plug is used with aviation and exceptionallyhot engines Iprovic'le holes a in the metal casing a and holes t in the cap g for allowingA of a free crenlation'of air in the spab and between'the cap and the electrode and insulator e and tov further enhance this cooling I provide fins u'oii' the 'metal body a so that' the rush of'air'will assist in the coo1ing.

' maat I claim is:-

unginos comprising; :i tubular metal body :i0

foi-mcd with :m opper cnlni'gcrl chamber und :i lower smaller vhnnilmr with :i con'- trzuztocl neck hoLWcQn the two chambers, au, insulator of tubular form und of materially' less dnnotcr than the upper'chnmber and 35 }',r joc.ting into the latter` the lower portion of the insulator being enlarged and snugly Afitting n. portion of tho woll of the Smaller chamber, :in iusulntiugrcupjshnpetl'cnp fitted into the. upperend of the metal body and de- 40 pending into the chamber around the upper end of the said insulator, and :m electrode extending through thc insu|:xto r nml 'upl' minllythrough the cup-shaped insulating cap, the upper portion of tlie electrode being' -15 scre\vthre;ulel and oumiged 'by n n'ut witlil Tui iu the cup of the said cap und alsoibyf'n upper nut having coperative bearing l\ vitl1"' thertop 'of the cap",' `a' sparkngpoint being

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