Патент USA US2134946код для вставки
Nov. 1, 1938. R. T. HURL‘EY 2,134,946 . I RADIO SHIELDING MEANS Filed Nov. 2, 1935 ‘ 2 Sheets-Sheet vl 1N VENTOR. K M _ ATTORNEY. Nov. _l, 1938. " R. T. HURLEY 2,134,946 RADIO SHIELDING MEANS Filed Nov. 2, 1935 2 Sheets-Sheet 2. IN VENTOR. ATTORNEY. Patented Nov. 1, 1938 2,134,946 , UNITED STATES PATENT OFFICE 2,134,946 RAD“) SHIELDING MEANS Roy T. Hurley, Dobbs Ferry, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware . Application November 2, 1935, Serial No. 47,963 14 Claims. (01. 241-5) This invention relates to electrical apparatus. whereby servicing of the same is rendered easy and more particularly to means for shielding and convenient and an effective continuous screen electric circuits such as, forexample, the ignition is insured. circuit of a radial aircraft engine. One of the objects of the present invention is to provide a novel ignition harness for an internal combustion engine whereby electrical radiation from the ignition circuit thereof is substantially eliminated. I - A still ‘further object is to provide a novel electrical radiation screen for an electrical con- .5 ductor which‘ is ?exible, moisture proof and heat resisting and which has a high resistance to penetration by gasoline, oil and the like and a high resistance to abrasion, thus rendering the It is well-known that electrical radiations from the high tension oscillating circuits employed in same durable and dependable. the operation of internal combustion engines in terfere with radio reception in the vicinity of said engine, such as in an airplane, and render the reception of signals, course indicating beams, and the. like either ‘impossible or inaccurate. for screening the electrical radiations ofthe ig nition circuit of an internal combustion engine Means have accordingly been heretofore provided for screening the ignition circuits of engines by enclosing the various live parts thereof in metal current conducting casings and connecting the latter to each other and to ground for the purpose of avoiding any substantial radiations. The as semblies or harnesses heretofore provided have _ Another object is to provide a novel harness which is simple in construction and of light weight, yet durable, effective and dependable in 15 service. > , The above and further objects and novel fea tures of the invention will more fully appear from the following detail description, when taken in connection with the accompanying drawings. 20 It is to be expressly understood, however, that the - not, however, been entirely satisfactory, since the drawings are for the purpose of illustration only and are not designed as a de?nition of the limits of the invention, reference for this latter purpose same have not beenv dependable for long periods being primarily had to the appended claims. of service and the servicing of the same has been In the drawings, wherein like reference char acters refer to like parts throughout the several inconvenient and difficult, comparatively slight repairs requiring the use of a large number of tools and a considerable amount of time and views, 25 ' Fig. l is a diagrammatic front view of a radial engine illustrating a portion of the shielding har- , 30 labor by skilled mechanics. Furthermore, the radio shielding apparatuses heretofore‘ provided ness comprehended by the present invention; which are at all practical have been such as to subject the ‘insulation of the ignition cable to ‘Fig. ,2 is a perspective view showing. the rear of said engine with the novel harness installed deterioration by gasolinaheat, oil and moisture, thereon; and in many instances to abrasion, thusreducing the life and dependability of the circuit as well as the effectiveness of the screen. Fig. '3 is a perspective view illustrating one 35 type of magneto shield which “may be employed in It is accordingly another object of the invention to provide a novel ignition harness for screening an internal combustion engine ignition-circuit which is so constructed that the same may be readily and easily installed on and removed from the engine as a unit, said harness being further adapted for installation so that necessary repairs to the circuit or harness can be readily and quick ly made without removing the entire harness and without removing or disturbing adjustments of other engine parts. ' _ Still another object of the invention is to pro vide novel means for effectively screening elec trical radiations emanating from a current carry ing conductor. - A further object is to provide a novel Joint for connecting the individual parts of radiation screening means for an electrical conductor carrying out the present invention; ‘ Fig. 4 is a detail view, with parts broken away, of a manifold ring and connections therefor em ployed in carrying out the invention; 40 , Fig. 5 is a partial sectional view, with parts broken away, taken on line 5—5 of Fig. 4; Fig. 6 is a section taken on line 6-6 of Fig. 4; vFig. 7 is an enlarged sectional view of a por tion of the wall of the shielding conduit of Fig. 5; 45 Fig. 8 is an enlarged section taken on line\8—-8 of Fig. 6; ' Fig.9 is a sectional view, with parts broken away, taken on line 9-9 of Fig. 4; v ' Fig._ 10 is an end view and transverse section 50 taken on line l0—-|0 of Fig. 9; . Fig. 1-1 is a front elevation of one type of spar plug shield which‘may be employed in carrying out the invention; and, ‘ Fig. 12 is a side elevation, partly in section and 55 2 > 2,134,946 with parts broken away, of the spark plug shield of Fig. 11. ' The live parts of the oscillating circuit of the ignition system of aircraft engines, for example, radiate magnetic lines of force which rise and fall with current oscillations in the high tension circuit and which interfere materially with radio reception in the vicinity of the engine. In order to prevent such interference it becomes necessary to provide a metallic shield about all of said live parts for the purpose of intercepting said lines of force and dissipating the energy thereof in the form of electric current which may be con ducted to ground by the shield. If the shielding 15 means is to be satisfactorily effective, there must be no substantial break or opening in the shield ing system, and it is accordingly highly desirable that all live wires and current carrying parts be completely surrounded by metal when originally 20 installed and that the same be of such construc tion and materials as not to be susceptible to too rapid deterioration and frequent failure by reason 'of the elements and other conditions under} which the same are required to operate. Acord 25 ingly, the shielding harness of the present in vention, in the form illustrated, completely en closes the» two independent ignition circuits of a dual ignition radio aircraft engine wherein a set of spark plugs is mounted at the front of the 30 engine cylinders and a second set is mounted at satisfactory since sparks are apt to occur between the engine and metallic braid when the latter rubs against the former, thereby producing a fire hazard. A fabric covering is not practical be cause the same wears too rapidly, becomes oil soaked, and is apt to take fire at engine tempera tures. Furthermore, oil, gasoline and moisture penetrate the fabric and seep through the woven metallic shielding and deteriorate the rubber and shellac employed on the current carrying con ductors. Novel flexible tubing is accordingly provided for shielding the conductors between magneto shield 20 and manifold tube [5 and between the latter and spark plug shields 24, which tubing is not subject to the hazard of sparking and has a high resistance to penetration and deterioration by gasoline, oil, moisture, heat and abrasion. One form of the novel tubing is constituted by mani fold conduit N which is adapted to shield a plu rality of conductors 22 and comprises a braided metallic tube 25, such as phosphor bronze fiat braid, surrounded by a second braided tube 26 of smaller tinned copper wire. The former assists the latter in shielding the current carrying con ductors and gives su?icient rigidity to the conduit the rear thereof, each set being connected to to prevent excessive twisting and vibration there of. Surrounding said metallic tubes and in inti one of a pair of magnetos secured to the rear of mate contact therewith is a covering 21 of syn the engine. The novel ignition harness provided is so con 35 structed as to facilitate the servicing and insure .permanence of operation. In addition, the length of the cable and weight of the entire unit is minimized, all of which are important con siderations, particularly in aircraft engines. As shown, said harness comprises a pair of arcuate manifold tubes or rings [5 and 16 extending over an arc of about 120° and adapted to be secured to the front and rear, respectively, of the engine I‘! . by means of suitable brackets, not shown. 45 shielding conduits for conductors, the outer sur faces of which have been constituted by metallic braid or fabric. The former type is not wholly Referring more particularly to the shielding harness of that part of the ignition system which includes the front spark plugs, manifold ring I5 is preferably constituted by a thin, light metal tube, such as copper or bronze, which offers compara 50 tively small resistance to the flow of electric cur rent, and may be plated with nickel, chromium, cadmium or the like, if ‘desired. Said tube, in the embodiment illustrated, is made in two parts, one of which is in the form of a T-joint l8 secured to 55 the remainder of the tube by means of an in ternally threaded coupling nut l8a adapted to co operate with threads on tube portion l5. One branch of joint I8 extends rearwardly for con nection with a novel ?exible manifold conduit I! which is in turn connected in a novel manner to hereinafter appear to a two-part metallic shield 20 supported by and covering the high tension terminals of a magneto 2|. The individual cur rent carrying conductors 22 extend from a thetic rubber, which is not materially affected by gasoline, oils and other solvents of natural rub ber which is employed for insulation on con ductors 22. Said covering also has a high resist ance to heat, moisture and weather elements and is tough enough to resist abrasion brought about by movement and vibration of the conduit in con tact with the engine by reason of wind currents and other causes. By way of example, one suitable composition of synthetic rubber which may be employed in mak ing covering 21 comprises about 100% of chloro prene as a base, the chemical ‘formula of which is 10% of zinc oxide, 10% of magnesium oxide, 5% of wood resin, and 40% of soft carbonblack. The composition made in accordance with this typical formula may be extruded onto braided wire tubes 25 and 26, thus causing the same to ?ll the spaces between the strands of wire forming said tubes. Additional rigidity and resistance to twisting movements is thus given to the entire conduit without impairing the longitudinal ?exibility thereof, and relative movement of tubes 25 and 26 is obviated. Another form of the novel shielding conduit provided by this invention is illustrated in Fig. 8 wherein conduit 23 is shown as comprising a wire braided tube 28 having a covering 29 of syn thetic rubber of the character above described extruded thereon. In order .to give the conduit terminal of the magneto through manifold con duit l9, manifoldv tube l5 and thence through rigidity, (to prevent crushing the latter and to novelly constructed conduits 23, 23a and spark facilitate the insertion of current carrying con plug shields 24 to the front plugs of the engine. . ductors 22, conduits “23, 23a also include a coil Conduits 23, 23a are connected to manifold tube 70 l5 and shields 24 in a novel manner to appear hereafter. Conductors 22 may be constituted by standard copper wire insulated with natural rub ' ber, fabric and shellac in a well-known manner. In ignition harness heretofore provided, the 76 most successful units have employed ?exible spring 30 within braided tube 28, said spring be- , ing under torsional compression and exerting a radial pressure "against the inner walls of said braided tube. As noted above, the present invention, com prehends the use of a plurality of metallic mani fold tubes 15 and I 6 in lieu of the single tube ‘2,184,946 heretofore used in devices of this character and mounted on the rear of the engine, the arcuate length of said tubes-being materially reduced for the purpose of reducing the weight of the har ness and facilitating installation and servicing thereof. To further facilitate installation and servicing, novel connecting means are provided 3 shields. The inner endscf conduits 23a extend through a triangular-like coupling member or ferrule 42 (Figs. 9 and 10.) having three passages therethrough, the inner walls of which are closely engaged by .the synthetic rubber covering 29 of conduits 23a. Braided metallic tubes 28 and springs 30 of said conduits extend beyond the in combination with the shielding tubes and con ‘ ends of covering 29, are ?ared outwardly over duits whereby the harness may be readily dis the inner face of ferrule 42, and are secured 10 assembled after installation without interfering thereto. The securing means is preferably con 10 with the engine parts and without removing the stituted by soft soldering in order to permit the entire shielding unit and whereby dust and mois renewal of one of the conduits 23a without de ture are excluded therefrom. The ends of the stroying the entire three-way connection. A cir shielding conduits and novelly constructed to cular ?ange 43 is provided on the inner end of constitute part of the coupling means and to in ferrule 42, which is adapted to be held in elec 15 sure good electrical connections between the sev eral parts of the shielding harness. As shown in connection with conduit I9, said coupling means comprise a pair of ?anged metallic fer 20 rules 3i and 32, Fig. 5, the former of‘which has a tubular portion extending into the con duit and the latter a tubular portion which ex tends ‘outside of the conduit in intimate contact ' ' with covering 21. The ?anges on said ferrules extend radially and outwardly in' overlapping re lation and the end portions of braided tubes 25 and‘ 26 which extend beyond covering 21 are ?ared outwardlyv between said ?anges. Said ?ared portions and ?anges are secured together 30 by suitable means such as solder, thus forming a conduit with a clean, as distinguished from a ragged end, and insuring an effective electrical connection. A pair of internally threaded cou pling nuts 33 having inturned ?anges 34 engag 35 ing the ?ange of ferrule 32 are adapted to coop erate with threads on a branch of Tejoint l8 and an extended portion of magneto shield 2d to complete the shielding means between the magneto and the manifold tube. Upon screw 40 ing coupling nuts 33 tightly into position, the ?ange of ferrule 3! will be held in firm contact with joint'id or shield 20, as the case may be, thereby forming 'a tight joint and sure electrical connection between the shielding parts. ' A modified coupling is shown for connecting conduits 23 to manifold tube l5 wherein the inner ends of the three conduits which are shown connected to said tube intermediate the ends of the latter are provided with a pair of ?anged ferrules 3i‘: and 36 (Fig. 8) which have tubular portions that extend inside of spring 30 and out- . trical engagement with a threaded collar 44 brazed to the end of manifold tube ill by means of an internally threaded coupling nut 45 having an inwardly extending lip 46 engaging the outer face of ?ange 43. 20 One type of spark plug shieldlwhich may be employed in carrying out the invention comprises a cup-shaped body portion 41 adapted to be re movably secured to a spark plug 48 by means of a pair of collars 49 and 56 having coacting ?anges, the former of which has threaded en gagement with an opening in the bottom of body 121 and the latter a like engagement with the metallic body of spark plug 48. An opening at the top of body 41 is covered by a metallic plate ment with the edges of said opening by a ?anged ring 53, said ring being secured to the body by peeping the lower edge of the ?ange thereof 35 over an annular head on body M. For the pur pose of liberating ozone which. will be generated ‘ within body él'l during engine operation and at the same time avoiding entrance of dirt and moisture, a channel 5c is formed around said 4.0 body beneath ring 53 and has small alternate openings 55 and %_into body-4T and to atmos phere, respectively. Threaded into an opening in the side of body“ is a short tubular member 58 to which a shielded conduit 23 or 23a is adapt ed to be connected by coupling nut W in the manner above described. The means for establishing an electrical con nection between conductor 22, which extends through conduit 23, and spark plug electrode 59, 50 are preferably constituted by a pin til, an en side of covering 29, respectively. The ?anges on said ferrules overlap and have'the ?ared end of tube 28 soldered or otherwise suitably secured therebetween. An externally threaded coupling nutv 3T is adapted to threadedly engage a nipple 38 which may be permanently secured, as'by larged head portion of which is slidably mounted in a metallic cylinder 6i’, the pin being normally held in engagement with electrode 59 by a spring 62 within said cylinder. The inner end of the wire of conductor 22 is ?ared outwardly and soli means of silver brazing, over an opening in the insulating spool 64. The inner end ofcylinder wall of manifold tube l5. Nut 31 is adapted to so 56 and a plurality of layers of mica insulation 52, which plate and layers are held in engage dered to a metallic? Washer 83 molded into an Si is held in engagement with the ?ared end of 60 engage the ?ange of ferrule 36 and press the ‘ the wire of conductor 22 by an expandible lock 60 ?ange of ferrule 35 against the plane surface of an internal ?ange 39 on nipple 38, thereby form ing a tight joint and electrical connection. An interally threaded coupling-nut 40 (Fig. 12) hav--' ing an internal lip 4| for engaging the ?ange of ferrule 36 maybe employed for connecting the outer end of conduits 23 to spark plug shields 24. In the illustrated embodiment of the inven-' tion, three of the current carrying conductors 22 spring 65 adapted to coact with an internalgroove in spool M. The movement of said spool in body 41 is limited by a shoulder thereon which v - cooperates with an internal shoulder on tubular 65 member 58. If desired, a rubber washer 65 may be interposed between the ends of conduit 23 and the outer ends of members 58 and 64. The- shielding harness‘ for ‘thatportion of the 70 are led out from each end of manifold tube I5, > ignition circuit including the rear spark plugs is 70 ‘l8 through shielding conduits 23a to the indi vvidual spark plug shields 24. Conduits 2311 are substantially the same as the harness above de scribed except for minor details of desi n neces similar in construction to conduits 23, and the sitated by the particular engine construction to outer ' ends thereof are provided with similar which it is to beadapted. 75 coupling means for connection to said spark plug The manifold conduit . connecting manifold tube IE to the shield on 75 4- _ 2,184,946 magneto 2la is of course much shorter than con duit I9, but of the same construction. There is thus provided a novel radio shielding harness for the high tension shielding circuit of an internal combustion engine whereby electrical radiations and consequent interference with ra dio reception in the vicinity of the engine are eliminated. Novel shielding means for a current carrying conductor are also provided, which 10 means are so constructed as to offer high resist ance to deteriorating causes and agencies present in the operation of an internal combustion engine, thus increasing the life of the harness and de creasing the possibility of failure thereof. Said 15 means are also so constructed as to be readily installed and serviced in the ?eld as well as in extending between said ?anges in electrical con tact therewith. 4. An electrical radiation screen for an electric current carrying conductor comprising a ?exible metallic tube, a covering of synthetic rubber on said tube, a metallic ferrule surrounding said cover adjacent an end of said tube, said ferrule having an exterior annular ?ange at the outer end thereof, and means for electrically connect ing the end of said metallic tube to said ?ange. 10 5. An electrical radiation screen for an electric current carrying conductor comprising a ?exible metallic tube, a. covering of synthetic rubber therefor, a metallic ferrule at an end thereof surrounding said covering and electrically con 15 nected to said metallic tube, and a coiled me the shop. tallic spring under torsional compression within Additionally, there is provided a novel ignition harness for the ignition system of a dual igni tion engine wherein each ignition circuit is in dependently shielded so that in the event of damage to the shield of one circuit the other cir cuit may be employed singly for operating the said ?exible tube. engine without any interruption of satisfactory 25 radio reception. The invention also compre hends a novel harness wherein a single shielding conduit is passed between the,hot cylinders of the engine instead of nine conduits, as has been the practice in similar devices heretofore pro 30 vided, said single conduit being so constructed as to withstand for long periods of time the in tense heat, the action of gas, oil and other mois tures, and the wearing tendencies to which it is subjected. . Although only- one embodiment of the inven tion has been illustrated and described, it is to be expressly understood that the same is not lim ited thereto but that various changes may be made. For example, manifold tubes l5 and i8 40 may, if desired, be further divided into pairs on some types of engines to increase the facility with which the same may be serviced. Many other changes may also be made in the design and arrangement of parts illustrated, as will now be 45 apparent to those skilled in the art, without de parting from the spirit and scope of the inven tion. Reference will accordingly be had pri marily to the appended claims for a de?nition of the limits of the invention. What is claimed is: 1. A radio shield for an electric current car rying conductor comprising a ?exible metallic tube, a synthetic rubber covering on said tube, and a metallic ferrule at each'end of said tube 55 surrounding said cover, ‘the ends ofsaid tube 35 being electrically connected to said ferrules. 2. A radio shielding conduit for an electric current carrying conductor comprising a ?exible metallic tube, a synthetic rubber covering on said 60 tube, a metallic ferrule at each end of said tube surrounding said cover, the ends of said'tube being electrically connected to said ferrules, and a metallic spring under torsional compression within said metallic tube and exerting a radial ‘pressure against the walls thereof. 3. A radio shield for an electrical conductor comprising ' a ?exible metallic tube having1 a ?ared end portion, a covering of synthetic rub 70 ber for said tube, a metallicferrule surrounding said covering adjacent anend thereof, ‘a metallic spmg inside of said tube, and a ferrule extend ing into_said tube interiorly of said spring, said ferrules having overlapping exterior ?anges thereon with the ?ared end of said metallic tube 6. A radio shield for an electrical conductor’ comprising a loosely braided wire tube, a com paratively closely braided wire tube surrounding said ?rst tube, and a cover of synthetic rubber extruded onto said tubes to surround the same and fill the spaces between the strands thereof. 7. In apparatus of the character described, a 25 metallic tube having a threaded collar on an . end thereof, a ?anged ferrule having a plurality of longitudinal passages therethrough, a ?exible metallic conduit extending into each of said pas sages and secured to said ferrule, and a coupling nut adapted to threadedly engage said collar and having an internal ?ange adapted to engage the ?ange on said ferrule to hold the latter in contact with said collar. 1 8. In apparatus of the class described, a metal lic tube having a threaded portion at an end thereof, a coupling member having a plurality of passages therethrough and a ?ange adjacent one end thereof, a ?exible metallic conduit ex tending through each of said passages and se 40 cured to said member, a synthetic rubber cover ing on each of said conduits engaging the walls of said passages, and a coupling nut adapted to cooperate with said ?ange and the threaded portion of said tube to secure said member and 45 tube together and establish an electrical con tact therebetween. 9. A radio shield for an electrical conductor comprising a braided wire tube, a covering 'of synthetic rubber extruded onto said tube to sur 50 round the same and ?ll the spaces between the ‘strands thereof, and a metallic spring within said tube engaging the inner walls thereof. 10. In apparatus of the class described, a me tallic tube having an opening in the wall thereof, 55 a ?anged nipple covering said opening and elec trically secured to said tube, a ?exible metallic conduit, 9. covering of synthetic rubber on said conduit, a ferrule on an end of said conduit hav ing a ?ange, a ?ared end of said metallic con duit being in electrical contact with said ?ange, and a coupling nut threadedly engaging said nipple and adapted to hold said flange and ?ared end against said~nipple whereby a tight Joint is formed and said tube and conduit are held in electrical contact. Y 11. In a radio shielding ignition harness for an internal combustion engine, a substantially rigid metallic conduit, an internally threaded nipple extending outwardly from said conduit, 70 an internal ?ange on said nipple having a plane ~ face, a ?exible metallic tube, a ferrule having an . external ?ange surrounding said tube, and a coupling nut threadedly engaging said nipple to press a ?ared end of said ?exible tube between 75 5 , said ?anges whereby a tight joint and electrical contact is established between said conduit and tube. ‘ 12. In a radio shielding ignition harness for an internal combustion engine, a substantially rigid metallic conduit, an internally threaded nipple extending outwardly from said conduit, an internal ?ange on said nipple having a plane face, a ?exible metallic tube, a covering of syn thetic rubber on said tube, a coil spring in said tube, a ?anged ferrule surrounding the cover ing adjacent an end thereof, a ?anged ferrule 13. An electrical radiation screen for an elec tric current carrying conductor comprising a ?exible metallic tube, a metallic ferrule sur rounding said tube adjacent an end thereof, a metallic spring inside of said tube, and a ferrule 5 ‘extending into said tube'interiorly of said spring, said ferrules having overlapping exterior ?anges thereon that have electrical contact with the end of said metallic tube. 14. An electrical radiation screen for an elec 10 extending interiorly of said spring, the ?ared tric current carrying conductor comprising a ?exible metallic tube, a coiled metallic spring in side of said tube, and a metallic ferrule extend end of said ?exible tube extending between the ?anges on said ferrules, and a coupling nut' ing into said tube interiorly of said spring, said ferrule having an external ?ange electrically 15 threadedly engaging said nipple to clamp said ferrule ?anges and ?ared portion between said nut and the plane face of said nipple ?ange. connected to said tube. - ‘ ROY T. HURLEY.