-21siSO,855 @for-la doiigid46rableidUtance-@l*ymd-froin beat-.., t,r$,n=itted _ frC=" the ''ei&AuA @as @ well sA from mechaniewl abrasion duef @to bendiw of the cable '@';tomake!cbupliligbonnections.@L-.1tis-furthernoW.L @that the@@ kalihg., -washer ti -, ma'y be - integrall@, 5@ fdrmed -with 'the sloev6@ @21 tiiough the separate@ fro 'con stru6ti6n JiL' pvefciftbli6%@ m@ I a@n@ stan dpoint It -is furthef @t@o'be;xmderstwd that the term rubb dr@ a;i3@ rd6rrtng: to @;l the. I tubularl protecting- 10 slee ve and seaiing disc is intended to refer to L rubb er and the various compounds havi ng properties somewhat simflar to natural rubb er and generauy referred to in the art iLs "synt hetic rubber." 13 Tho ugh pi-eferred forms of the invention have bee n illustrated and described other forms and modi fications wiR become apparent to those WH ed in the art as fauing within the scope of t-he invention as defined by the appended claims. 20 I claim. 1. A moisture proof terminal construction for igniti on cables of the character used in conjunction with shielded L spark plugs having a grounded shiel dmg sleeve projec#ng from the plug body; 25 com prising an annular thimble of a rigid insulatin g material having a substanti&Uy closed lowe r end provided with a cortact adapted to engage the central electrode of the spark plug, said cont act being adapted to be electricauy connect- 30 ed to the cable conductor, a resilient sealing wo,s her seated on the bottom of said thimble and adapted to tight-"y encompass the conductor of said cable and to abut the end face of the ingill -t-i-o-p and protective covering thereof in 35 seali ng relation, and a tubular sleeve of rubber or like mat;erial surrounding said cable, the end face of said sleeve also en aging, said washer in 9 seali ng relation and the said tubular shield tightl y engaging the interior walls of said thim- 40 ble in sealinp. relation, said tubular sleeve extending along said cable from the said thimble a dis tanc e sufficient to prevent contact between said cabl e and any of the smeldmg elements of the awo ciated spark plug. 2. A terminal construction for high tension cabl es of the character employed *ith shielded spar k plugs having grounded tubular shielding elem ents extending from the body of the plug; com prising a tubular rubber thimble adapted to 50 enco mpass the exterior of the cable for a length equa l to or greater than the length of the shielding elements of the associated spark plug, the said thimble abutting the end face of the insulation and protective covering of the.cabl6 in seal- 55 ing relation and sealingly encompassing the projecti ng portion of the cable conductor, an insulatiri g ferrule made of a rigid insulating material bavi ng a substantiauy closed end provided with a contact adapted to be electrically connected to 60 the cable conductor, said ferrule being adapted to be forced onto said cable o-ver the end portion of said tubular rubber thim'ole and the contact ther eon being adapted to engage the central spar k plug electrode when the ferrule and cable 65 are inserted in assembled relation into the shielding elements of the plug. 3. A moisture proof terminal construction for high tension shielded spark: Plug cables of the e.ha racter in which the electrical conductor Is To surr ounded by insulation made of rubber or the iike and covered by a brilided fabric material coat ed with a water PrOOlIng mzterw; COMPrising a tubular sleeve made of a resiuent water proo f iusul&WW materw baving a length 75 equiLltoorgreaterthanthe%lengthottheshielding. elements of an associated spark plug, Wd sleeve being slipped-, M Lover sead cable to surround @ ther, termiinal @.md thermf La resilient sealing., washer @ adapted Lto .@: t@;@tiY. @ encompass the projectingi portion - of . the:, cable conductor and@:to itbut the md faces of @the cable Insulation @protective covering L=d said slftve, a rigid fer;@l; Df insulating. material:having a substantially clored end provided with.,an electrical emtact,@ Wd @ ferrule being: fqrced L onto tJ@e end of :mid 'cable. over-. the tubular sleeve until the seaung washer is comprelsed agabut the closed end of the ferrule, and anelectrical connection between said contact and the conductor in said cable. 4. The structure as claimed in claim 3, including a second tubular sleeve surrounding Wd first named sleeve the lower end of which engages the upper end of the said ferrule, and a radiauy extending annular sealing washer integrauy formed with said second sleeve and serving as a packing seal for the junction of the spark plug smeld %,ith other cable shielding elements. 5. A terminal construction for high-tension cables of the character employed with spark plugs having grounded tubxilar shielding elements extending from the body of the plug; comprising a tubular thimble of rubber or like mateiial adapted to encompass the exterior of the cable for a length equal to or greater than the length of the shielding elements of the awociateld spark plug, said thiinble abutting the end face of the insulation and protective co@;ering of the cable in seaung relation and sealingly encompassing the projecting portion of-the cable conductor, an insulating ferrule made of a rigid insulating material having a substantially closed end provided with a contact adapted to be electrically connected to the cable conductor, said ferrule being adapted to be forced on to said cable over the end portion of said thimble and a resilient tubular sleeve made of rubber or like material surrounding said thimble in sealing relation and abutting the upper end of said feriule, the upper end of said sle-eve having integrally formed therewith, an annular radially extending sealing element adapted to serve as a seal for t-he junction of the spark plug shield with other cable shielding elements. 6. In a terminal construction for high tension ignition cable for use in conjunction with @hielded spark plugs, said calile being of the character in which the electrical condiactor is surrounded by insulation of rubber or like material; comprising a rigid ferrule of in.%ill ting material having a substantiary qiosed end provided with an electrical contact, said ferrule being forced over the end of the cable, an electrical coiinection between the said contact and the cable conductor, g. resilient cylindrical tubular sleeve made of rubber or. like material encompawing the cable in sealing,relation, one end of said sleeve being placed in aoutting and seaung relation with the top of said ferrule and the upper end of said sleeve being provided with an annular integrally formed radiauy extending disc or washer adapted to serve as a packmg seal for the junction of the shielding weU of the spark plug with other cable shielding e!lements, the overall length of said tiibular sleeve being subst-antially equal to or greater than the outside diameter of the sleeve so that radial pressure exerted on the seaung washer wUl be distributed into the sleeve without necking the irotective tn-gulation of the cable.

4 2,280,855 7. In a terminal construction for a high-tension Ignition cable used In conjunction with shielded spark plugs of the character in which the electrical conductor is surrounded by ftisulation of rubber or like material and having a rigid 5 thimble of ceramic or like insulating material encompassing the end of the cable, said thiinble 1- .aving a contact thereon adapted to be electrically coimected to the cable conductor; of a moisture sealing cyundrical sleeve of rubber or like io material surrounding said cable in sealing relst.ion and positioned so as to abut the upper end of said thimble in sealing contact, said sleeve having formed thereon adjacerit its upper end, P. radially extending annular disc or washer adapted to serve as a packing seal for the shielding well of the spark plug with other cable shielding elements, said sleeve having an overah length greater than the thickness of sWd washer porti(n so as to distribute the radial stresm on the washer into the body of the vleeve to thereby reduce necking of the insulation on the cable. JOHN J. ROSE.

Patented Apr. 28, 1942 21280,855 U-NITED STATES PATENT OFF:ICE 2,280,855 SPAP-LC PLUG CABLE TERNMAL John L Rome, Dayton, Oblo Application October 15, 1941, gerw No. 415,072 7 Claims. (CL 123-169) (Granted =der the act of March 3, 1993, as April 30, 1928; 370 0. G. 757) The Invention described herein may be manu- extending the service life of the ignition cables, factured and used by or for Govemment for gov. emmental purposes, without the payment to me of any rgyalty thereon. This lnvenuon relates to improvements in the 5 cable termin.als for shielded spark phip whereby the Rfe of the high tension cables conducting the high voltage sparking current to -the plugs Is greatly extended. Shielded spark plugs as now generally used 10 on aimraft engines for Ignition purposes include in addition to the piug proper, a grounded tubular metal shield into which the upper parts of the spark plug core and central electrode project, the Inner surface of the sweld being Uned with a adt- 15 able insulating material. The spark plug cable Is formed of a central conductor aurrounded by rubber insulation which in tum,to covered by a braided fabrlc sleeve coated with lacquer to render it waterproof and to protect the rubber 20 Insulation against oxidation. The terminal end of the cable is pushed Into an snnular sleeve or thiinble i iade of "BakeRte" or ceramic lnmil ting material which is provided on ita end with a suitable contact to which the cable conductor Is con- 25 nected. The cable termin I with the aswmbled Insulating sleeve is then pushed into the tubular shield of the plug, the contact on the sleeve engaging a contact secured to the upper end of the central spark plug electrode. The spark plug 50 cable is then PuRed through a curved tubular metal elbow forming part L of the swelded plug flnd which is secured by a union nut to the threaded upper portion of the ablelding tube, the joint being sealed by a resilient rubber sealing 35 washer which encompasses the cable. The above noted elbow at Its outer end serves as a connec@ tion for the usual braided metal conduit or harness through which the igniuon citble is passed. A great deal of dimculty has been experienced 40 with swelded Ignition apparatus of the character described which results from several different causes, among which are the high temperatures eidsting adjacent the plugs due to beat transmi - sion therethrough; high temperatures in the 45 shield elbows, due to the latter being in the vicinity of the engine exhaust conduits- mobiture -- --, 9 col lecting along the cable, and especially at the plug terminal; necking of -the insulation on the cable by the se&Ung washer, caugm damage to Go the lacquer protecting the fabric covering of the cable; and damage to the lwuer coating In PuUing the cable through the shidd elbow. In accordance with the present invention many of the above troubles are nitnimized thus gmtly 55 and the improvements in accordance with the invention may be attained by simple means without changing any of the standard ignition units now employed in the art. In accordance -,with--t_he invention the "Bakelite" or ceramic sleeve, or thimble, generany em-@ ployed on the terminal end of the cable is retained and the cable itself is preferably chown of a smaher outside diameter than would ordinarfly be employed with the respective terminal sleeve or thimble. A thin waued rubber tube is slipped over the cable i-oY-sFuch a length that the tube will extend at least to or beyond the outer end of the shield elbow when a&semble& AL:dat rubber washer it placed over the cable conductor at the terminal end thereof so as to &but the end of the rubber tube and braided fabric covering on the cable. The end of the cable is then forced into the conventional ter-inll thimble with the rubber washer tightly seated on the bottom thereof thus seaung the cut end of the braided covering of the Ignition cable against moisture. The protective rubber sleeve aerves to materiauy protect the ignition cable proper from damage from high temperatures both.withIn the plug shield and in the sweld elbow. and u sea g washer pressure at the junction of the plug shield and the sweld elbow, preventing necking and fracture of the lacquer coatihg on the cable. The rubber sleeve also protects the lacquer coating oxx the cable against damage while being pulaed through the sweld elbow and is further effective to protect the cable against the effects of high tempemtures In the vicinity of the shield elbow due to heat from the engine exhaust conduits. The protection of the lacquer coating on the cable at those points where the same is liable to be mechanically damaged is of great importance because damage or abrasion of the lacquer coating wiu allow moisture to enter the braid which permlts a corona discharge, causing the production of ozone which rapidly oxidizes the rubber insulation of the cable causing the same to sweu and crumble and necessitating frequent renewal of the Ignition cables. 7he principal object of the invenuon Is therefore the provision of a spark plug terrnin%Ll for ignition cables employed in conjunction with swelded plugs which provides a greater protection to the cable in-gillation in those pbrtions adjacent and within the plug swelding elements subject to high temperatures, and Insures &dequilte protection of the insiil ting cover of the

2,280,855 cable from moisture and mechanical damage or abrasion. A flirther object of the invention is the proywon of a terminal for hiih tension igriition cable employed with shielded spark plugs; com- 5 prl%ing a rigid thimble of insulating niaterial having a contact thereon adapted to be elec'@rically connected to the cable conductor, a washer of rubber or like material adapted to encompass the projecting portion of the cable 10 conductor and to abut the end face of the cable insulation in sealing relation thereto, and a sleeve of rubber or like material surrounding the cable for a length at least sufficient to prevent contact of the cable with the shielding ele- 15 ments of the spark plug and the walls of the thimble and at its lower end engaging said sealing washer in sealing relation. Other objects of the invention will appear by reference to the detailed description hereinafter 20 given and to the appended drawing in which: Fig. I is a side elevation partly in section illustrating the novel cable terminal assembled in a shielded spark plug, and; Flg. 2 is a sectional view to an enlarged scale 25 illustrattag the details of the terminal of Flg. 1; and Mg. 3 is a view simjlar to Mg. 1, luustrating a modified form of the invention. Referring now to Flgs. 1 and 2, the reference 30 numeral 1, genera indicates a conventional type of shielded spark plug employed In aircraft , engines and having a metal body 2, imulating core 13 and a central high tension electrode 4 provlded at its upper end with a contact button 5. The 35 plug is provided with the -asual grounded metal shield 6 screwed into the upper end of the spark iplug body 2 and lined with an ingill ting material such as "Bakelite" or a ceramic composition, as indicated by the reference nuineral 7. The to u.Dper end of the tubular shield 6 is threaded as at 8 to -eceive a coupling i which se;.,ves to connect a tubulax shiel@d elbow 10 to the shield 0, the outer end of the eroow being suitably threaded to receive the coup4ug member Of a 45 weU known type of braided metal wnduit II *hich serves to electrically screen the cable between the distributor and the spark plug. The high tension cable is generally indicated by the reference numeral 14 and coml_3rises hn 50 electrical conductor 15 covered by a thick layer o@@' rubber insulation 16, which in turn is protected 'Dy an external layer of braided fabric 17 coated with lacquer which protects the braid from moisture, and if undamaged, greatly mini- 55 mizes the possibility ef corona discharge which cause.v rapid deterioration of the rubber Insulation. The spark plug terminal on the cable comprises an annular insulating sleeve or ferrule IS 60 made of "Bakelite" or of ceramic material substantially closed at Its lower end by a moulded in metal washer or disc 10 to which the cable conductor 95 is soldered or otherwise electrically connected on assembly. The disc 19 is provided a5 with a contact 20 in the form of a spiing which Is adapted to engage the contact 5 on the central spark plug electrode 4. The ferrule or sleeie I& with the closure f 9 forms a thinible which encloses the erid of the cable and is a suding :ftt in 70 the tubular shield 8. The cable f 4 inst,-ead of directly contacting the thirable 18 is separated fherelrom along the bottom face of the cable b@- a seaung washer 21 made o@* rubber or simuar thimble,and abuts the insulation 16 and cut end of the braided fabric covering 17 of the cable In water tight relation, preventing the entrance of moisture on the frayed end of the covering 17 and tightly encompassing the conductor 15 of the cable. The cable is further Insulated from the inner walls of the thimble by a tubular rubber sleeve 22 which extends along the cable for a length sufficient to pass through the shield elb6w IO into the metal conduit or shielding harness I 1. A rubber or other resilient packing washer 23 encompasses the sleeve 22 and serves as a packing seal for the coupling 9. In practice the cable 14 is chosen of a diameter slightly smaller than would otherwise be employed axid the tubular sleeve 22 made of rubber or similar material is slipped over the end of the cable, the sleeve theri being inflated with air under pressure is slipped on the cable for the desired length. The sleeve 22, cable covering 17 and insulation 16 of the cable 14 is cut. transversely and the proper length of conductor is left projecting for connection to the spring contact 20.. The rubber washer 19 is then forced over the projecting portion of the conductor and seated a&ainst the transverse end faces of -the sleeve 22 and the protective covering and insulation of the cable, and MaY be cemented to the tubular sleeve 22 to form a bondtherewith. After passing the cable through the elbow 18 the iusulating thiinble 18 is forced over the end of the sleeve 22 until the washer 21 is tightly seated on the closure member 19, the conductor 15 then being conneeted to the contact 28 and the tliimble I 8 inserted in the Plug sllield I to c.omplete the assembly. The tubular sleeve 22 protcets the lacquer coatink on the cable from mechanical damage whilt,, being puued through the shield elbow 10 and further materic-Uy protects the cable covering from the effects of h@;gh temperatures in the vicinity of the elbow IO due to heat froni the engine exhaust ftianifolds. The portion of the sleeve 22 within the thimble I 8 serves in conjunction with the washer 21 to protect the cable against any enirarice of moist@ure and further materially reduces the effects of heat transmitted from the plug body and core from. damaging the lacquer coating on the cable exterior. The sleeve 22 further serves to distribute the presqure of the sealing washer 23 so that the cable proper is not necked beneath the washer and the lacquer coating at this point is not damaged as freqiiently occurs in prior constructions. The modifled form of the irvention illustrated in P'ig. 3 is similar In all respects to the construc,tion of ngs. @ and 2 except that the ferrule or thimble I 8 is sbortened and a second tubular sleeve 24 is placed oiler the sl,-eve 22 and terminates iit itS UpPer en-d in an integrally moulded radially extending seal'mg washer 25 whicii @,erves the same func7,tion as the sealing washer 23 of Mgs. 1 and 2, but more effectively distributes the s-,alirig pressure to eliminate ne(,king of the.cable and to prevent moisture from pawiiig along the cable to the terminal connection thereof. It is to beanderstood that while the invention has beenillustrated m applied to spark plugs employing shielding elbows, t-he tprminal coistructicn i-,; equally applicable to those plilgs i-n which the ignition hamess is coupled directly to the plug shield and in such cases the tubular ,;Ieeve is made of such a length that the rable is material which seats on the bottom I I of the 75 . well protected adjacent the cou@ling member and