US2286918A

US2286918A - Spark plug shielding

Info

Publication number: US2286918A
Application number: US481766A
Authority: US
Inventors: Joseph J Mascuch
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-09-13
Filing date: 1930-09-13
Publication date: 1942-06-16
Anticipated expiration: 1959-06-16

Description

Junelfi, 1942. J. J. MAscucH SPARK PLUG SHIELDIHG Filed Sept. 13, 1930 M W a u 0.

INVENTOR.

H B. U E. m i H m. E. JY B AT RNEY.

Patented June 16, 1942 UNITED I STATES PATENT oFFrcE SPARK k Applicatlzi 481,788

18 Claims.

This invention relates to spark plug shielding and has for an object to protect spark plugs as used on internal combustion engines and to shield such plugs against electronic emissions thereby preventing interference with radio apparatus. Other objects or the invention will be understood from the following specification and the accompanying drawing, selected to show my invention in several forms, and in which, Fig. 1 is a sectional elevation of an engine cylinder with a spark plug and connection shielded according to this invention, Fig. 2 is a modified construction alternative to Fig. l with the engine cylinder sectioned, Fig. 3 is a form of sheet metal shield for the spark plug, partly sectioned to show the interior construction.

The use of radio apparatus in the vicinity of internal combustion engines requires the spark plug connections to be enclosed with a metallic casing which is grounded to prevent interference with the radio set. It has also been found that spark plugs as used on airplane engines when in high altitudes lose some of their insulating qualitiesv due to the rarifled air in which they are operating, which condition is remedied in the present invention by placing the spark plug in a hollow vessel filled with transformer oil and provided with a. suitable cap to retain the contents. This hollow vessel may be screwed into the engine head and provided with exterior fins for cooling the contents.

Air cooled aviation engines in particular are subject to local hot spots in the combustion chambers which limit the usable compression ratio and therefore the power output. For example, there is usually a high temperature zone at the spark plugs and adjacent combustion chamber wall, particularly in the case of plugs located on the leeward side of an air cooled cylinder head.

The present invention provides additional radiating means for such points without change in the present standardized dimensions of the plugs, which should remain interchangeable between various engine designs.

According to the present invention, an extenslon in intimate thermal union with the cylinder head is disposed about the spark plu to form a base for the application of a substantially increased number and area of cooling fins.

In the preferred form shown in the drawing the extension is indicated as being conveniently formed integral with the usual spark plug hole bushing and comprises an enlarged cylindrical extension surrounding the plug and provided with a plurality of integral annular radiating fins.

This cooling element is preferably made of material of high thermal conductivity, 1. e., a material characterized by a relatively small temperature gradient, whence it will be seen that the bushing into which the spark plug is screwed will be substantially reduced in temperature, with a corresponding reduction in the temperature of the spark plug itself and of the surrounding cylinder wall.

The stem of the spark plug is connected through an elbow with the conductor in a novel manner which admits of quick replacement and insures complete metallic shielding.

Referring to the drawing, II is a. sectioned view of the engine cylinder head which is provided with cooling fins I 2 and a sleeve IS. The spark plug, which is of the usual commercial type, is indicated at H and the conductor from the spark plug is indicated at IS.

The shield in Fig. 1 comprises the hollow con- I tainer l6 which is screwed into the engine head at H and is provided with the cooling fins IS. The threaded base of the spark plug l 4 is screwed into the container it at l9. In this construction the spark plug is removed with the container.

The container I6 is provided with a cover 2| of insulating material which is covered on the outside with a metallic shield 22, which is preterably applied by electro-plating. This cover is made in the form of an elbow with a collar at 23 which seats on the rim of the container is end encloses the interior. The interior of the cover is formed in a hollow cone as indicated at 24 and is provided with a metallic washer at 25 centered over the stem of the spark plug and threaded to receive the screw 26. The cover 2| is held on the container l6 by means of a bail 54 carried by the container I6. e

The screw 26 clamps the coil spring 21 in place to engage the stem of the plug and is adjustable for stems of diflerent lengths. Screw 26 is provided with a tapered point as shown which penetrates the insulating wall of the conductor l5 and engages the stranded conductor 28, effectively making connection therewith. A washer is provided at 29 on the end of conductor ii to which the strands of 28 are soldered with the object of .holding the strands and insulation in place. The shank of the elbow 30 is provided with a threaded ferrule to receive the clamping nut 3| which clamps the tapered rubber washer 32 to make a waterproofed connection at the outlet. The conductor I5 is provided with a suitable metallic coating for grounding purposes. The conductor l may also be provided with a shielding conduit as shown in my co-pending application Serial No. 394,618, filed September 23, 1929.

In Fig. 2 the container for the spark plug is made of a short piece of tubing seated On the engine head and suitably secured in position. The tubing ll seats in a turned groove at 43 in the casting of the head I I and is held in place by the set screws 42 in the air cooling fins of the engine. This construction is less expensive than that shown in Fig. 1 and may be adapted to existing engine heads. The cover 2| is held in position by the bail 54.

In Fig. 3 a hollow container is preferably spun 7. A spark plug shield comprising a cup to surround the spark plug and a cap for the cup, said cup and cap being liquid-proof and said cup being adapted to be filled with a. dielectric liquid to increase the insulation of the plug.

8. A spark plug shield comprising a metallic cup to surround the plug and a'cap of dielectric material for the cup .providedwith a-collar adapted seat on said cup, ametallic cover on said cap in the form of a' thin sheath which is grounded to. said cup, and a sleeve of dielectric material betw" en said cup and the spark plug to prevent flashes from the spark plug to said cup.

from sheet stock and is held in place by the flange of the spark plug. The container 5i has a base flange at 52 which is clamped against the engine casting by the flange .of.- the spark plug. The rim is curled over at 53 to provide a seat for thecover 2| and to support the bail which holds the cover in place by spring action.

It is apparent that the hollow chamber surrounding the spark plu in Figs. 1, 2 and 3 can be filled with a suitable di-electric in liquid or plastic form to increase the insulation of the spark plug. It will be noted that the extension of the cover atv 24 into the container and below the metallic coating 22 increases thesparking distance between the stem of the spark plug and its metallic enclosure.

The invention may be applied in other forms additional to those shown.

Having thus described my invention, 1 claim:

1. A shield for a spark plug comprising a sleeve enclosing the spark plug, a cover for said sleeve comprisin a body of insulation coated with metallic foil, a collar on said cover resting on said sleeve and making electrical contact with said coating and means for securing said cover to said.

sleeve.

2. A shield for a spark plug comprising a. sleeve enclosing the spark plug, a cover for said sleeve comprising a body of insulation coated with metallic foil, a collar on said cover resting on said sleeve and making electrical contact with said coating, a. conductor outlet in said cover and means for securing said cover to said sleeve.

3. A shield for a spark plug comprising a sleeve enclosing the spark plug, a cover for said sleeve comprising a body of insulation coated with metallic foil, a collar on said cover resting on said sleeve and making electrical contact with said coating and means for securing said cover to said sleeve to make a moisture-proof closure.

. 4. A shield for a spark plug comprising a sleeve enclosing the spark plug, a cover for said sleeve comprising a body of insulation coated with metallic foil, a collar on said cover resting on said sleeve and making electrical contact with said coating, a conductor outlet in said cover and.

means for securing said cover to said sleeve so that the conductor outlet may extend in various directions from said sleeve.

5. A spark plug shield comprising a cup to surround the spark plug and a cap for the cup, said cup being adapted to be filled with a semisolid dielectric substance to increase the insula tion of the plug. I

6. A spark plug shield comprising a cup to surround the spark plug and a cap for the cup', said cup and cap being moisture-proof and said cup being adapted to be filled with a semi-solid dielectric substance to increase the insulation of the plug.

I 9. The combination with an engine cylinder, a spark plug and a radio shielded cable therefor; of a shielding shell secured to the cylinder and surrounding the spark plug and having an opening therein at its outer end for the insertion and removal of the spark plug, a cap covering said outer end opening and comprising a conductor, a metallic sheath, and an insulating lining extending between theterminal'end of the spark plug and the wall .of the shielding shell, and means to engage each component part of the cap with the corresponding component parts of w shape admitting of its fitting engagement within the space between the terminal end of the spark plug and the inner wall of said shell, a metallic shielding within which the normally exposed portion of said cap is encased, a conductor means in said cap contacting with the terminaliend oi the spark plug, and means to engage each com- I.

ponent part of said cap with the corresponding component parts of the radio shielded cable.

11. The combination with an engine cylinder, a spark plug and a radio shielded cable therefor; of a shielding shell encircling the spark plug and bearing at its inner end on the engine cylinder and open at its outer end to admit of the insertion and removal of the spark pliIg,a cap covering said outer end opening-and comprising a conductor, a metallic sheath, and an-insulating lining within the embrace of which the terminal end of the spark plug is seated, and means to engage each component part of the cap with the corresponding component parts of the radio shielded cable.

12. The combination with an engine cylinder, a spark plug, and a radio shielded cable therefor; of a shielding means comprising a base member bearing on the engine cylinder, a cap detachably seated on said base to complete the enclosure of the spark plug and comprising a conductor, a metallic sheet, and an insulating lining into which the spark plug extends, and means to engage each component part of the cap with the corresponding component parts of the radio shielded cable.

13. A device for cooling the hot spot in the wall of an engine cylinder in the vicinity of the spark plug and the spark plug itself comprising an exteriorly finned metallic shell surrounding substantially the entire projecting length of the spark plug, the wall of said shell being wholly independent of and spaced from the structure of the spark plug whereby the latter may be bodily removed and withdrawn without disturbing in any way the connection between said shell and the engine cylinder.

14. A device for cooling the hot spot in the wall of an engine cylinder in the vicinity of the spark plug and the spark plug itself comprising an exteriorly finned metallic shell having an exteriorly threaded bushing and a shoulder around said bushing, both said shell and said bushing being in intimate'thermal contact with the cylinder wall; the finned portion of said shell being substantially coextensivewith the entire projecting length of the spark plug and being open at its outer end to admit of the spark plug being bodily removed and withdrawn from said shell without disturbing in any way the intimate thermal contact aforesaid, and said shell having formed therein at its inner end and within said bushing a threaded opening into which the inner end of the spark plug is screwed.

15. In a radio shield for spark plugs, a cap to cover a plug, said cap comprising a metal shell and a body of dielectric material in the shell, a lateral extension on said shell and dielectric body provided with a bore to receiv a conductor, a washer carried by the dielectric body, and a contact means disposed through said washer, the lower end of said contact means'being adapted to contact a spark plug and the upper end thereof being adapted to project into said bore to contact a conductor.

16. In a radio shield for spark plugs, a cap to cover a plug, said cap comprising a metal shell and a body of dielectric material in the shell, a lateral extension on said shell and dielectric body provided with a bore to receive a conductor, a threaded bushing carried by said dielectric body, a contact screw adapted to be inserted into the bore through the bushing for the purpose of piercing the insulation of and making contact with a conductor in the bore and a resilient contact means carried by the screw to make contact with a spark plug.

17. In a radio shield for spark plugs, a cap to cover a plug, said cap comprising a metal shell and a body of dielectric material intimately attached to said shell, said shell and body each having a. lateral extension formed with a bore to receive a conductor and a partially resilient contact means removably supported from said dielectric body, the upper end of said contact means being adapted to pierce the insulation-oi and make contact with a conductor in the bore and the lower end of said contact means adapted to extend below the dielectric body to make contact with a spark plug.

18. In combination with a spark plug and a cable therefor, a spark plug shield comprising a bushing disposed in the cylinder head around the spark plug and formed with an extension projecting above the surface of the cylinder head and surrounding the base of the spark plug and a cap disposed over the upper part of the plug and in electrical contact with the extension on the bushing.

JOSEPH J. MASCUCH.