US2105791A

US2105791A - Ignition shielding

Info

Publication number: US2105791A
Application number: US550076A
Authority: US
Inventors: Joseph J Mascuch
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-07-11
Filing date: 1931-07-11
Publication date: 1938-01-18
Anticipated expiration: 1955-01-18

Description

, Jan. 18, 1938. J. J. MAscucH ,7

IGNITION SHIELDING Filed July 11, 1931 6 Sheets-Sheet l INVENTOR 7555a? J/V/Isc'ucw l5 ATTORNEY Jan. 18, 1938. J MASCUCH 2,105,791

IGNITION SHIELDING Filed July 11, 1931 6 Sheets-Sheet 2 INVENTOR Ms ATTORNEY J. J. MASCUCH IGNITION SHIELDING Filed July 11 Jan. 18, 1938.

1931 6 Sheets-Sheet 3 INVENTOR 4 JESEPH JT/VAscz/cfi 6 ATTORNEY 1938. .1. J. MASCUCH IGNITION SHIEL DING Filed July 11, 1931 6 Sheets-Sheet 4 R O T N E V m vTosfP/v J Mas cuc /r 5 6 lf/S ATTORNEY Jan. 18, 1938. J MASCUCH 2,1Q5,791

IGNITION SHIEL DING Filed July 11, 1951 6 Sheets-Sheet 5 INVENTOR 6 :I/V/ISLl/C'l/ f/l ATTORNEY Jan. 18, 1938. J. J. MAscucH' IGNITION SHIELDING Filed July 11, 1931 6 Sheets-Sheet 6 INVENTOR JZJSEPH TIN/950110 H15 ATTORNEY Patented Jan. 18, 1938 UNITED STATES PATENT OFFICE IGNITION SHIELDING Joseph J. Mascuch, Newark, N. J. Application July 11, 1931, Serial No. 550,076

20 Claims.

This invention relates to means for shielding the ignition system of internal combustion engines and is a continuation in part of application Serial No. 394,618, filed September 23rd, 1929.

One object of the invention is to provide a conduit system for ignition which will completely isolate, electrically, the ignition system of an internal combustion engine.

When internal combustion engines using electrical ignition systems are used in proximity to radio receiving apparatus, there is a radiation of electrical waves from the ignition system, which radiation causes interference with the reception of radio equipment.

By properly surrounding with a conductive casing, allof the parts of the ignition system through which high frequency currents pass and grounding the said conducting casing, it is possible to dissipate the energy of the electrical radiations directly to ground, thereby preventing the aforesaid interference. It is an object of this invention to provide a conductive casing or shielding for the entire ignition system of internal combustion engines, whereby interference to radio communication and equipment installed in proximity to the engine will be eliminated.

This invention is applicable to all types of combustion engines and particularly to engines on units such as aeroplanes, motor boats, automobiles, submarines, etc. For the purpose of illustrating and describing the invention only its application to a radial aeroplane engine is shown. However, this is not to be construed as a limitation of the uses of the invention. The invention 35 may also be used on stationary engines.

In order to provide an effective shielding means it isnecessary to shield the low and high tension conductors, the starting and switch circuits, the spark plugs, magnetos, distributors, generator,

49 and battery, or any other means forthe production and distribution of electrical energy that may be used. All of the electrical equipment is insulated. The shielding is accomplished by enclosing all of the electrical equipment in highly 5 conductive casings or shields which are grounded or bonded to the engine and fuselage of the aeroplane so that any electrical radiation will be absorbed and grounded by the shields.

Due to the extreme conditions under which an 50 aeroplane engine operates it is necessary, in order to have an effective shield, that the ignition system be protected from the possibility of failure due to outside interference. A short circuit or break in any part of the ignition system will 65 cause most serious damage. Oil, water or gaso-,

line will deteriorate the insulating material, at. first permitting corona. discharges and eventually resulting in a total breakdown of the insulation, thereby causing the necessity for the replacement of the defective conductor. Therefore, an- 5 other object of the invention is to provide a shielding means for the ignition system which will prevent water oil, gas or other detrimental foreign substances from reaching the conductors or other parts of the ignition system, and which, 10 by enclosing the entire system in a fireproof casing will minimize the risk of fire caused by short circuits, resistance flashes and sparking.

In order for a shielding system to be practical it must be constructed so that it may be easily 15 applied to an engine and constructed so that parts thereof may be removed or replaced without the necessity of dismounting the engine and removing the entire shielding means. In the past, shields applied to aeroplane engines have been 20 placed on the rear of the engine and have not been built in sections. In order to either apply or service the shielding system it has been necessary to practically dismount the engine and the shielding means. Therefore, another object of 25 the invention is to provide a shielding system which may be easily and quickly applied to the front of the engine behind the propeller, without the necessity of disturbing the engine, and which may be made in sections so that any part may be easily and quickly removed and another part substituted without removing the entire shielding means. By placing the shielding means immediately behind the propeller it is subject to blast of the propeller which prevents the accumulation of oil, water, or other detrimental foreign substances on the shields. A furtherobject of the invention is to make the jointsor connections of such sections thoroughly water and oil proof so that no moisture or other detrimental agents can get into the shielding means.

A further object of the invention is to provide a main manifold from which sub-conduits lead to the individual spark plugs and magnetos. In the .past, in shielding the conductors it has been common practice to directly shield each lead from the magneto to the spark plug, thereby in-' creasing the capacitance between the ignition conductor and ground, thereby reducing the intensity of the spark, resulting in a loss of power or failure of the compressed charge to ignite, thereby charging the exhaust manifold with an explosion maximum which subsequently explodes in the manifold, greatly increasing the fire hazard. Since theisdmary wiring of the magnetos is grounded and the shielding is grounded,

the greater the length of the shielding the more.

resistance will be set up in the magnetos. If this resistance rises to a point where the magnetos are not strong enough to overcome it, the engine will miss. By using a single main manifold for all the wires the capacitance of the shielding system is decreased and the resistance in the magnetos materially reduced.

Where rigid shielding is used the vibration causes rapid wear and abrasion of the insulating materials of the conductors. As soon as the insulation is damaged electrical emanations are released therefrom-with resultant loss of power and efficiency. Therefore, a further object of the invention is to provide flexible conduits to the spark plugs and magnetos so that the harmful effects of vibration will be minimized. This insures longer wear and less likelihood of breakdown. Where rigid shielding is used the vibration causes the shielding to crystallize and break. By using flexible shielding this danger is eliminated.

In high tension conductors it is essential that the outer surface of the insulating material be smooth and that the conductor be kept free from kinks or sharp bends at which points charges of high potential may build up. In case the smooth 5 or lacquered surface of the insulation becomes damaged at points or sharp bends, the accumulated charge will create a corona discharge from the rough or fuzzy points, thereby gradually deteriorating the entire insulating material and causing a complete break-down of the insulation at this point, resulting in a short circuit. By making ,the inside of the conduits smooth, the lacquer finish of the conductors is not damaged when they are drawn through the conduits. It is therefore a' further specific object of the invention to provide a shielding means wherein the inner surface of the conduits will be smooth and wherein the outlets from the main conduit will be curved so that sharp bends and kinks in the conductors will be impossible. By making the conduits larger than the conductors an air gap will be left in the conduit around the conductors. This air gap increases the insulation and also prevents, to a certain extent, wear andabrasion of the conductors.

At high altitudes or under other conditions of low atmospheric pressure, at which time the conduction of the surrounding air is very much greater than the conduction of the compressed gas between the gap of the spark plug points, there is danger of the ignition current flashing over or sparking to a. nearby grounded conductor and natural sparking outlet at spark plug points. It is standardpractice to maintain a distance of at least A;ths of an inch between any uninsulated conductor carrying ignition current from any grounded part. In providing a shielding means for the spark plug, it would be necessary to use a large and bulky grounded conductor to enclose the spark plug, unless other insulating means is provided. It is therefore a further specific ob- J'ect of this invention to provide a shielding means of moderate size for the spark plug which will provide a distance of at least ths of an inch between all uninsulated parts carrying high tension ignition current from surrounding grounded parts. Changes of temperature will cause condensation of moisture on the insulating body of the spark plugs and snow, water or ice which may leak through the shielding means and gather on the insulated body of the spark plug will cause a short circuit and make it extremely difficult to start the engine without first wiping off all mois ture from the insulated body of the spark plug and spark plug leads. It is therefore a. further specific object of this invention to provide a waterproof and air tight shielding means for the spark plugs.

The invention consists of the construction, combination and arrangement of parts as herein illustrated, described and claimed.

In the accompanying drawings, forming part hereof, is illustrated a form of embodiment of 'the invention, in which drawings similar reference characters designate corresponding parts, and in which:

Figure l is a front elevation of a radial aircraft engine, showing the application of the in vention thereto;

Figure 2 is a fragmentary detail in side elevation showing one conduit to the spark plug on the rear side of the engine;

Figure 3 is a rear elevation of a shielding sys tem, showing the main manifold with the flexible conduits extending therefrom;

Figure 4 is a fragmentary detail in elevation, partly in section, showing the connection between the parts of the main manifold;

Figure 5 is a rear elevation of a coupling means to the magneto, showing part of the magneto covers;

Figure 6 is a side elevation, partly in section, of the couplings shown in Figure 5;

Figure 'I is a fragmentary detail, partly in section, showing the method of attaching the main manifold to the crankcase;

Figure 8 is a composite plan view, partly in section, showing one outlet from the main manifold and one type of shielded spark plug;

Figure 9 is a front elevation, partly broken away, of a spark plug shield;

Figure 10 is a vertical section taken approximately on line l0|0 of Figure 9, looking in the direction indicated by the arrows;

Figures 11 and 12 are fragmentary details showing the method of holding the conduits to the engine;

Figure 13 is a horizontal section on line l3-l3 of Figure 12, looking downward;

Figure 14 is an enlarged detail, partly broken away, showing the structure of the flexible conduit; and,

Figures 15 and 16 are diagrammatic plan views of modified systems of wiring showing the use of a junction box.

Referring to the drawings 2|, d8Sigliat8S the crankcase of an aircraft engine having radial cylinder blocks 22 extending therefrom. The cylinder blocks 22 carry push-rod casings 23 and the propeller 24 is carried on the center of the crankcase 2|. Disposed on the crankcase 2| is a two-piece manifold 25. The manifold 25 may be of any shape or contour desired to fit any particular engine, such as oval, straight, round, etc. The manifold 25 is here shown as being made in two parts but it may be made in one or several parts as necessity or efficiency dictates. The manifold 25 consists of a metallic tube having closed ends, and having a smooth interior and a metal gasket 29 is disposed between the two sections to insure a tight closure and to insure a good electrical contact. It will be borne in mind that all connections in this invention must be both liquidproof and made .so as to form a continuous electrical conductor.

The manifold 25 is secured to the crankcase 2| by means of brackets 30. The brackets 30 may be disposed at any point around the manifold 25. The brackets 39 are silver-soldered to the manifold 25. While the brackets 30 may be secured to the manifold 25 in any suitable manner it has been found that the use of silver solder is more efllcient, giving a stronger bond for the weight of solder used and leaving a smooth surface to prevent the accumulation of dirt, etc.- The brackets 30 are provided with openings 3| through which studs 32 are disposed to hold the manifold 25 to the crankcase 2|, as best shown in Figure-7.

Disposed around the manifold 25, on the outside thereof, are outlets 33, for the purpose of leading the ignition wires to the spark plugs. The outlets 33 may be made as a part of the manifold 25 but also may be made separately and silver-soldered to the manifold 25. The outlets 33, as 'best shown in Figure 8, comprise a tubular body 34, the center line of which extends outward at right angles to the manifold 25.

The manifold end of each member 34 is flared outward on one side at 35. 'The opposite side 36 describes a longer curve before reaching the manifold 25. The purpose of this curved section 36 is essary in the ignition wire when passing from the manifold 25 through the outlet 33. An ad-- ditional advantage of the curved portion 36 is that it indicates in which direction a wire will run in the manifold 25, thus assisting in arranging the proper assemblage of the ignition wires. The other end of the tubular member 34 is provided with a screw-threaded section 31. On the inside, adjacent the outer end, the member 34 is provided with a beveled face 38 for the purpose hereinafter described.

The ignition wires or conductors 39 are encased in insulation 40 and pass from the manifold 25 through the outlet 33 to the spark plugs. Disposed around the conductors 39 between the outlets 33 and the spark plugs are conduits 4| The conduits 4| are secured to the outlets 33 by means of interiorly screw-threaded collar nuts 42.

The conduit 4| is fabricated from three layers of material, as best shown in Figure 14, the inner layer. being formed of a single continuous strip of metal 44 spun upon itself to produce a flexible housing for the conductors 39 andinsulation .40. The strip 44 may be made of any suitable metal but is preferably made of aluminum. The Strip 44, in cross-section is substantialiy the shape of a block letter S and is so spun as to provide oppositely disposed interlocking flanges 45. When the strip 44 is spun a packing 46 is introduced between the flanges 45.

The packing 46 may be asbestos and is saturated with graphite to insure a good conducting element through the strip 44-. when the inner conduit has been spun as described air spaces 43 are left between the flanges 45, thus leaving room for flexing the conduit 4|.

With this construction the inside surface 41 of the conduit 4| is made perfectly smooth so that when the conductors 39 with the insulation 49 are drawn through the conduit 4|, the lacquer finish on the insulation 40 will not be damaged. Even though the conduit 4| be bent or flexed the to eliminate the sharp bend otherwise nec-.

side thereof.

inner surface 41 will still be smooth and thus preserve the insulation 40. As pointed out heretofore if the insulation 40 is damaged in any way a loss in efficiency in-th ignition system will result. The inside of the conduit 4| is larger than the conductor 39 with its insulation 40. This leaves an air gap inside the conduit M which greatly increases the insulating qualities and prevents abrasion of the insulation 40.

Disposed around the inner conduit formed by the strip 44 is a jacket or casing of braided wire 49. Many types of wire may be used but it has been found highly successful to use a braiding of fine-gauge tinned copper wire. On the outside of the conduit 4| is braided a protective casing or armor 49 composed of strips of metal or flat wire. The function of the armor 49 is to both protect the conductor 39 and act as an electrical conductor. Therefore, many types of armor may be used. However, it has been found that for flexibility, durability, strength and lightness, an armor made of phosphor bronze ribbon is highly successful. With this construction a continuous electrical bond is made between the layers of the conduit 4|.

Disposed on each end of each conduit 4| is a ferrule 59. The outer end of the ferrule 50 is crimped or spun against the armor 49 to hold the strips of the armor 49 from movement and to insure a good electrical contact. The center portion of the ferrule 50 is formed into an outwardly extending flange 52 by means of bending the ferrule 50 upon itself. The inner end 53 of the ferrule 50 covers the ends of the armor 49, the braid 48 and the strip or inner conduit 44', and is turned inwardly in the conduit 4|. The inner end 53 is pressed against the inside 41 of the conduit 4| so as to eliminate any raw edges and to present a smooth orifice for the conductor 39.

Disposed around the insulation 40 of the conductor 39 is a conical rubber washer 54. When a conduit 4| is connected to an outlet 33 the washer 54 strikes the beveled face 38 of the outlet 33 and the flange 5290f the ferrule 59 presses against the opposite face of the washer. The collar nut 42, when screwed onto the threads 31, forces the flange 52 against the washer 54, the conical face of which is forced against the beveled face 38 of the outlet 33 and makes a waterproof connection. When the washer 54 is thus held under pressure it holds the insulation 40, of the conductor 39 to the center of the outlet 33, thus preventing any possible friction against the inner wall of the outlet 33. the washer 54 being compressed by the nut 42 the washer 54 exerts a pressure against the nut 42 and acts as a lock-washer to hold the nut firmly in place so that the nut 42 cannot become loosened from vibration. This same effect is produced on all outlets where a conical washer 54 is used.

As shown in Figures 1 and 2 some of the condults 4| are shorter than others, for the reason that one set of conduits 4| must lead around the cylinder blocks 22 to the spark plugs on. thefar In order to retain the conduits 4| in position clips .55 and 55 are used, as best shown in Figures 11, 12 and 13. The clips 55 areused to hold the conduits 4| to the push-rod casings 23 and comprise a single strip of spring metal, the center portion 58 of which is bent upon itself to surround the conduit 4 A bolt 59 having a nut 60 is disposed through conduit 4|.to hold the the clip 55 adjacent the bent portion 59 securely At the same time on the conduit. The opposite portions of the clip 55 are curved as shown at 6| to surround the push-rod casings 23 and the ends 62 are flared or turned outward. With this construction, when it is desired to remove the conduit 4|, it is only necessary to pull the conduit 4| and the spring clip 55 will bend sufliciently to release the push-rod casings 23. In replacing the conduit 4| the flared ends 62 will force the clip 55 open so that it may be easily slipped on and off of the push-rod casing 23.

The clips 56 are used to hold the conduit 4| to one of the cooling fins 51 of the cylinder block 22. The clip 56 comprises a single strip of spring metal bent upon itself at 63 to surround the conduit 4|, with the ends 64 adjacent one cooling fin 51. A bolt 65 passes through the end 64 and the fin 57 and is secured by a nut 66. In removing the conduit 4| it is necessary only to remove the bolt 65, allowing the clip 56 to remain on the conduit 4|.

From the outlets 33 the conductors 38 surrounded by the conduits 4| lead to the spark plugs of the motor. If a shielded spark-plug such as shown in Figures 3 and 8 is used the conductor 39 is attached to the plug 6'! and the conduit 4| connected to the shielding of the plug. However, it is common to use ordinary unshielded spark plugs 68 and for this purpose a shield is provided to be used with such unshielded plugs, as best shown in Figures 9 and 10. The hereinafter described shield is made so that it may be used with any standard make of unshielded plug without the necessity of changing the shielding means.

The spark plug shield (as best shown in Figures 9 and 10) is designated generally as 68 and comprises an open-bottomed cup 10 adapted to surround the spark plug 68. The cup '10 may be made longer or shorter to accommodate various types of unshielded plugs 68. The cup 16 is provided with an inwardly tapered bottom portion 1| so that it may be easily seated on'the cylinder head of the engine. minates in an inturnedannular flange 12.- The flange i2 is adapted to abut the lower skirt ofthe plug 68. A copper washer 13 may be secured inside the cup 10 above the flange 12 so as to insure sealing contact of the plug 68 with the cylinder head of the engine. The cup." is made suificiently large to allow a socket wrench to be used to screw the plug'68 firmly into place. When the plug 68 is screwed into place the cup 16 will be rigidly held thereabout, and in electrical contact with the engine. On the upper edge of the cup 10 an annular projecting flange i4 is provided by bending the metal upon itself and a supporting shoulder 15 is formed by bending the metal of the cup 70 outward and downward. Before the end T6 of the cup 10 is turned inward as shown in Figure iii an annular L-shaped band of steel or other metal is placed in the housing formed by bending the cup 10 and the end 16 is then bent inward to hold the ring 11 in place. With this construction a firm foundation is provided for the shoulder with the use of the least possible material so as to reduce the weight. w

Disposed over the. cup 10 is a cap 18 formed or moulded of dielectric material such as Bakelite. The cap 18 iselectro-plated or otherwise covered with metallic foil or other conductive means 18 to protect the cap 18 and also to serve as an electrical conductor. On the lower end of the cap 16 is formed an annular depending flange with a recess 8| adjacent thereto. A special compound washer 82 is disposed in the recess 8| so that The tapered portion Ii ter-' when the cap 18 is disposed on the cup I8 the flange 14 on the cup 18 will ride against the washer 82 to make a moisture-proof seal. At the same time the depending flange 80 on the cap I8 will be in electrical contact with the shoulder 15 on the cup 16. A re-lnforcing member 83 is disposed in the top of the moulded cap 18.

On one side of the cap 16 is disposed a screwthreaded bushing 84 the inner face of which is beveled as shown at 85 to receive the tapered face of a conical washer 54. The portion of the cap I8 adjacent the conical washer 54 is also beveled so that the washer 54 will make a sealing contact against the cap 18 and the bushing 84. The usual collar nut 42 is used to hold the conduit 4| to the bushing 84.

Through the center of the bushing 84 and through the cap 18 is an opening 86 to accommodate the conductor 38 with the insulation 46. The opening 86 is made at an angle to the spark plug 68 so that the conductor 38 and conduit 4| will not be bent between the outlet 33 on the manifold 25 and the spark plug shield 68. The conductor 38 is usually made of strand wire and the ends of the strands of the conductor 38 are formed into one piece by solder 81, for the purpose hereinafter shown.

Set in the moulded cap 18 immediately above the spark plug 68 is an interiorly screw-threaded bushing 88. A screw 88 is disposed through the bushing 88 and is provided with a sharp point 88. The point 80 of the screw 88 is adapted to be forced through the insulation 40 and make contact with the conductor 38. The ends of the conductor 38 being held together by the solder 8'I the point 88 will spread the strands of wire as it is forced through and will insure a good electrical contact.

Carried by the lower end of the screw 88 is a coil spring 8|. The upper end of the coil spring 8| may be soldered to the screw 88 and the lower end of the spring 8| is-adapted to make contact with the stem of the spark plug 68.

The cap 18 being formed of dielectric material such as Bakelite, a short dependent skirt 82 is provided adjacent the upper portion oi the spark plug 68 and a second longer skirt 88 isiprovided adjacent the wall of the cup 16'. The skirt 82 serves as a container for the spring 8|.

The

skirts

82 and 83 are adapted to .prevent high tension flashes from the spark plug 68 to the cup 10. In flying at high altitudes in rare fled air these flashes will occur very frequently unless some means such as the skirts described are used to prevent them. With the spark plug shielding means here described it has been found very successful to fill the spaces in the cup 18, designated generally as 88, with a petroleum jelly. This is made possible by reason of the fact that the cup 16 and the cap I8 are entirely moisture-proof and will retain the petroleum jelly therein. By this method the flashes from the plug to the cup 16 are eliminated and a cooling means is aiforded for the spark plug.

The cap 18 is held onto the cup 18 by means of a spring bail 84 the ends of the bail 84 being disposed through the shoulder 15 and the ring 11. In screwing the spark plug 88 into position the cup 10 will be turned around and the bail 84 will not always be in proper position to hold down the cap 18. Therefore, a series of openings 85 are provided so that the bail 84 may be placed in any desired position. The ring 1'! acts as a bearing for the bail 84 and prevents the distortion of the openings 85 by the.bail 84. At the top of the ball 94 is provided a ball 96 which is free to rotate on the bail 94. When the cap 18' With this construction the bail 94 will at all times hold the cap 18 firmly on the cup 10 but will allow the cap I9 to be quickly removed at any time.

In aircraft practice dual ignition systems are often used.. Therefore, two magnetos 99 and I are provided to supply electrical impulses to their respective series of spark plugs. In order that the wires from the' spark plugs may lead to the magnetos, outlets IM and I02 are provided on the manifold 25. These outlets MI and I02 are similar tothe outlets 33 except that they are much larger in that several wires have to pass therethrough. These outlets may be placed at any point on the manifold 25, depending upon the type of motor used and the contour of the manifold 25. From the outlets IOI and I02 conduits I03 and I04 lead to the two magnetos. The conduits I03 and I04 are similar in construction to the conduits 4I but are made larger to-accommodate more wires. The magnetos 99 and I 00 are usually located behind the engine so that the conduits I03 and I04 lead from the manifold 25 over the engine and are held to the engine by clips I05 similar in construction to the clips 56. The conduit I03 terminates in an elbow I06 on the magneto 99 and the conduit I04 terminates in an elbow I01 on the magneto I00.

Since the mode of connecting the conduits I03 and I 04 to the outlets IOI and I02 is the same as the connection between the conduits I03 and I04 and the elbows I06 and I01 only the connection to the elbow I01 will be described. This connection is best shown in Figures 5 and 6. A ferrule I08 is disposed over the end of the conduit I04 and has its inner end I 09 turned inside of the. conduit I04 so as to present a smooth interior surface for the conductors 39. A collar H0 is secured by braising or other means on the ferrule I08. A collar nut I I l is provided on the conduit I04 similar to the collar nuts 42 heretofore described. The elbow I0! is provided with screwthreaded neck II2 onto which the collar nut III is screwed. I

A rubber gasket I I3 is disposed in the elbow I01 where said elbow I01 enlarges to form the neck ing a moisture-proof joint. .At the same time the ferrule I09, the collar H0 and the nut III acting on the neck II2, continue the electrical circuit desired. The elbow I0! is provided withan annular projecting shoulder I I4 near its lower end, from which shoulder II4 depends an annular flange II5. Two-piece covers II6 are provided to cover'the. exposed portions of the magnetos 99 and I00. The lower end III of the elbow I01 extends into the upper part of the two-piece covers H6 and is provided with an annular groove H8. The upper part of the covers H6 is provided with bosses II9 from which projects a flange II9a. The flange II9a interlocks with the flange II5 on the shoulder II4 of the elbow I01, making a moisture-proof enclosure. Disposed through the bosses II9 are bolts I20 operating with nuts I2I to hold the two-piece covers l|6 firmly together. On one cover plate H6 is The ferrule I08 is forced against the gasket I I3 and is held in place by the nut I I I, thus makdisposed aboss I22 which carries a set-screw The set-screw I23 projects into the groove -IIO on the elbow I01 and prevents the removal of the elbow I01 from the cover plates II6.

Inasmuch as the magnetos on various types of engines, may be in various positions, the groove H8 is annular so that the elbow I01 may be placed in the cover plates II6 from anyposition. Disposed on the inside of each cover plate H6 is a leaf-spring I24 secured at one end to the cover plates II6 by rivets or other suitable means I25. When the cover plates I I6 are forced against the magnetos 99 and I00 the springs I24 will hold the cover plates II6 under tension and thus reduce. vibration and wear.

The elbow I0I is provided with several outlets I26. These outlets I26 are similar to the outlets 33 on the manifold 25. Conduits I21 lead from the outlets I26. The conduits/I21 are similar in construction to the conduits 4|, but are made slightly larger so that one or more Wires may be carried therethrough. The conduits I21 are provided with ferrules 50 and collar nuts 42 and the connections to the outlets I06 are the same as the connections to the manifold 25 heretofore described. One conduit I21 leads to the starting or booster magneto I28 and another conduit I2I leads (to the switch I29. As shown in Figures 15 and 16 the conduits I2'I may lead to the junction box I30. The junction box I30 is formed of a piece of seamless metal tubing and is provided with outlets I3I similar to the outlets 33 heretofore described. The ends of the conduits I21 that enter the starting magneto I 28 and the switch I29 may be made with merely a ferrule I32 adapted to be frietionally held in'place by clamps I I33 on the switch I29 and the magneto I28. This construction is optional but inasmuch as the switch I29 and. the magneto I28 are usually mounted on the instrument panel of the aeroplane, there is very little danger of these terminals becoming wet and they are not subject to the strain that the other connections heretofore described are subjected to.

As shown in the lower portion of Figure 6, the' ends 81. of the conductors 39 may be provided with indicia. By having the ends of the wires numbered it is possible toquickly assemble the wiring in the shielding means without having to check each wire to find out where it should go.

In order to have the ignition system entirely shielded it is necessary to have the magnetos and switch shielded. This is accomplished by first insulating and then enclosing the parts in a continuous metal casing. When the switch or the magnetos are secured to the frame or body of the aeroplane the casings will act as a conductor. In the ordinary magneto illustrated the operating parts are protected in the main by a" metal casing which partially serves as a shield so that it is only necessary to add the cover plates II6 to form a complete shield for the magnetos. As pointed out heretofore one of the objects of this invention is to provide a system which will decrease the resistance in the high tension conductor used. In ordinary wiring systems separate wires are run from each spark plug to each magneto and from each magneto to each starting or-booster magneto, and from each of the three magnetos to the switch. By the use of the junc-' tion box I30 the length of wire necessary to make the circuits is materially reduced. Therefore, the resistance in the wires is reduced and the ignition system will work with much greater cil'iciency.

As to the shielding p1'operties,'-it will be seen that if any electrical radiations are released anywhere between the magnetos and the spark plugs such radiations will immediately be absorbed and grounded to the engine or fuselage of the aeroplane. Similarly, any electrical radiations coming from the outside will be absorbed and grounded before they can interfere with the ignition. From the foregoing it will be seen that interference with the radio reception and equipment by the ignition systemis eliminated.

It is known in aircraft practice that there are sources of disturbance of radio reception other than that directly produced by the ignition system. Even with the generator magneto cut-offthere may be currents produced, and the broad idea of the invention described is to effectively bond and shield all of the parts so that a continuous electrical conductor is afforded between all metal parts to ground. Unless this is done there is varying resistance between moving, poorly bonded, or between rubbing or vibrating metal parts which causes interference and noises in the radio receiver. Such interference and disturbance may even be caused by the sparking of a vibrating type voltage regulator used on the generators. To effect elimination of this it is desirable and necessary to enclose in highly conductive casings all parts carrying current of any description and to properly and securely bond at intervals to the aircraft such parts in order to obtain efficient uninterrupted radio reception.

Having thus fully described the invention what is claimed as new and desired to be secured by Letters Patent is:

l. A radio shielding system for both the high system of an internal combustion engine comprising a rigid manifold to enclose a plurality of wires, flexible conduits enclosing wires from the rigid manifold to the spark plugs, conductive housings around all of the operating units of the ignition system and conduits enclosing wires interconnecting units of the ignition system, the manifold and the several conduits being electrically connected and grounded.

3. A radio shielding system for both the high and the low tension portions of the entire ignition system of an internal combustion engine comprising a rigid manifold to enclose a plurality of wires, flexible conduits enclosing wires from the rigid manifold to the spark plugs, conductive housings around all of the operating units of the ignition system, conduits enclosing wires interconnecting units of the ignition system, the manition system of an internal combustion engine 4 comprising a rigid manifold to enclose a plurality of ignition wires, flexible conduits to enclose some of the ignition wires and junction boxes connected to some of the flexible conduits.

8. A radio shielding system for both the high and the low tension portions of the entire ignition system of an internal combustion engine comprising a rigid manifold to enclose a plurality of ignition wires, flexible conduits to enclose some of the ignition wires and junction boxes connected to some of the flexible conduits to decrease the electrical capacitance of the shielding system by decreasing the length of conduits necessary to interconnect the several magnetos and switch.

9. In a radio shield for both the high and the low tension portions of the entire ignition system of an internal combustion engine, a rigid manifold and a plurality of flexible conduits to enclose all of the wires of the ignition system, said members being electrically connected but readily separable to permit replacement of one or more members.

10. In combination with a radial aviation engine provided with magnetos, spark plugs and a propeller, a radio shielding means for both the high and the low tension portions of the entire ignition system comprising a rigid manifold disposed in front of the engine behind the propeller, said manifold being adapted to enclose and shield a plurality of ignition wires, a relatively large conduit extending over the engine to enclose and shield wires between a magneto and the manifold, flexible conduits to enclose and shield wires between the manifold and the spark plugs, conductive coverings around all of theoperating units of the ignition system and flexible conduits to enclose and shield wires interconnecting the operating units of the ignition system.

11. In combination with a radial aviation engine provided with magnetos, spark plugs and a propeller, a radio shielding means for both the high and the low tension portions of the enti? ignition system comprising a rigid manifold di posed in front of the engine behind the propeller, said manifold being adapted to enclose and shield a plurality of ignition wires, a relatively large flexible conduit extending over the engine to enclose and shield wires between a magneto and the manifold, relatively small flexible conduits to enclose and shield wires between the manifold and the spark plugs, conductive coverings around all of the operating units of the ignition system and flexible conduits to enclose and shield wires interconnecting the operating units'of the ignition system.

12. In combination with an internal combustion engine having magnetos, booster magneto, spark plugs and switch, a radio, shielding system for both the high and the low tension portions of the entire ignition system comprising a main manifold adapted to enclose a plurality of ignitionwires, a conduit connecting a magneto and the manifold and enclosing wires therebetween, flexible conduits enclosing wires from theman'is fold to the spark plugs, shielding coverings on the magnetos, booster magneto and switch, and flexible conduits enclosing wires interconnecting the magnetos, booster magneto and switch;

13. In combination with an internal combustion engine having magnetos, booster magneto, spark plugs and switch, a radio shielding system for both the high and the'low tension portions of theentire ignition system comprising a main manifold adapted to enclose a plurality of ignition wires, a conduit connecting a magneto and the manifold and enclosingwires therebetween, flexible conduits enclosing wires from the manifold to the spark plugs, shielding coverings on the magnetos, booster magneto and switch, flexible conduits enclosing wires interconnecting the magnetos, means to connect the flexible conduits to shielding of the spark plugs.

14. In combination with an internal combustion engine having magnetos, booster magneto,

spark plugs and switch, a radio shielding system for both the high and the low tension portions of the entire ignition system comprising a main manifold adapted to enclose a plurality of ignition wires, a conduit connecting a magneto and the manifold and enclosing wires therebetween, flexible conduits enclosing wires, from the manifold to the spark plugs, shielding coverings on the magnetos, booster'magneto and switch, flexible conduits enclosing wires interconnecting the magnetos, booster magneto and switch and means to connect the flexible conduits to shielding of the spark plugs, all ofthe elements of the shielding system being connected to form a continuous shield but each element being readily separable from the others to permit replacement of individual elements.

15. In a radio shielding means i'or the ignition system of an internal combustion engine, including spark plugs, magnetos with distributor blocks and high tension cables, said shielding means comprising a metallic casing means to cover and enclose thenormally exposed distributor blocks, said casing including a rotatable elbow formation through which said cables are directed for connection with the spark plugs.

16. A radio shielding means for both the high .and low tension sides of the entire ignition system of an internal combustion engine comprising sectional, rigid manifolds -to enclose and electrically shield a plurality of ignition wires, flexible conduits connected to the manifolds to enclose one or more ignition wires leading to the spark plugs and additional flexible conduits booster magneto and switch and starting -magneto to enclose and electrically shield low tension wiring of the ignition system.

17.1A radio shielding means for both the high and low tension sides of the entire ignition system of aninternalcombustion engine comprising sectional, rigid manifolds to enclose and electrically shield a plurality ofignition wires, flexible conduits connected to the manifolds to enclose one or more ignition wires leading to the spark plugs, radio shielding on the spark plugs, and additional flexible conduits to enclose and electri- 'cally shield low tension wiring of the ignition system.

18. A radio-shielding means for both the high and lowtension sides of the entire ignition system of an internal combustion engine comprising sectional, rigid manifolds to enclose and electrically shield a plurality of ignition wires, flexible conduits connected to the manifolds to enclose one or more ignition wires leading to the spark plugs,

radio shielding on the spark plugs, said flexible conduits being connected to the shielding of the plugs and additional flexible conduits to enclose and electrically shield low tension wiring of the ignitionsystem.

19. A radio shielding means for both the high and low tensionsides of the entire ignition system of an internal combustion engine) comprising secswitches, comprising complementary cover plates to enclose the normally exposed distributor blocks of a magneto, a rotatable elbow associated with the cover plates through which ignition wires pass from the magneto, a rigid manifold to receive a plurality of wires from the rotatable elbow,

shielding means surrounding the wires between the rotatable elbow and the manifold, flared, pro- ,7 jecting outlets on the manifold through which wires extend to spark plugs, flexible conduits enclosing the wires between the manifold and spark plugs, radio shielded spark plugs, said flexible conduits being connected to the shielding qfthe plugs, metallic casings around the switcii' and and flexible conduits enclosing wires interconnecting the several magnetos and switch. Josnruauascncm