US2047302A - Spark plug - Google Patents

Description

' .July 14, 1936. c. A. XA-RDELL SPARK PLUG Filed Feb. 20, 1934 luv w;

Patented July 14, 1936 PATENT OFFICE SPARK PLUG Charles A. We, mm. N. Y., assignor of one-half to Charles Coupe, Utica, N. Y.

Application February 20, 1934, Serial No. 712,238 6 Claims. (Cl. 123-169) In spark plugs now generally in use with internal combustion engines the main electrode extending through the central porcelain element of the plug consists of a wire of high heat resistance 5 but of low conductivity for the passage of the electric current. While it is desirable that the spark plug should have a high current strength this current strength is largely reduced by the high current resistance of these heat resisting l electrodes. Also, owing to the high heat resulting from the low electrical conductivity of these electrodes, they -are liable to burn out .or become rapidly deteriorated by pitting or otherwise.

This invention has for its object to produce a 15 spark plug which will afford a high current strength but which will not be liable to burn out or become pitted or otherwise deteriorated and thus it will have great durability and long, emcient life. To this end, according to the present 20 invention, the main electrode of the spark plug,

which extends through the central porcelain element of the plug, consists of a wire having a heat resisting core of low electrical conductivity, said core being cased or covered with a heat-resisting 25 laminated casing of high electrical conductivity. This laminated casing or covering will preferably be of copper or silver, and a heat resisting cement of graphite with a binder, although powdered carbon or a suitable powdered metal of high elec- 30 trical conductivity may be used in the cement if desired.

To transfer heat from the main electrode through the central porcelain element of the outside shell of the plug a gasket or gaskets of cop- 3 per will preferably be interposed between said porcelain element and said outside shell, thus somewhat cooling said main electrode, and reducing any tendency of its burning out.

In the accompanying drawing Fig. 1 is a ver- 40 tical section of a spark plug embodying the present invention.

Fig. 2 is an enlarged fragmentary section of the main electrode.

Referring to the drawing, l2 denotes the outer 45 shell or body of the spark plug having a threaded part I! to enable it to be screwed in working position, as usual. This shell or body I2 is of copper alloy of high heat transfer value or high heat conductivity, this alloy being preferably of about 50 80% copper with the balance of zinc, tin, lead and a small percentage of silver. The proportions of this alloy may, of course, be varied somewhat to vary the heat transfer value thereof.

The central insulating porcelain element I3 is 55 secured intheshell or body I: bya nut M which will preferably be of a copper alloy similar to said shell or body l2. Interposed between the lower part of the shell or body I! and the central porcelain element is is a copper gasket or ferrule I! of considerable length and a smaller 5 gasket I6 is preferably also interposed between the lower end of the nut i4 and the said porcelain body. These gaskets make air-tight joints at the places where they are located and serve to transfer heat from the porcelain body to the outer 10 parts.

Extending through the porcelain element I3 is a main electrode l'l consisting of a core ll of low electrical conductivity but which is of a high heat resisting alloy of nickel and chromium. This core has a. coating or casing l8 of copper outside of which is a coating or casing I! of silver, thus afiording a laminated construction of high electrical conductivity and high heat resistance. These elements i8 and I9 arein contact with each other, as clearly shown in Fig. 2. This laminated electrode is secured in the porcelain member by a heat resisting cement 20 of high electrical conductivity and high heat resisting quality, said cement being preferably of graphite with a suitable binder although powdered carbon or a suitable powdered metal may be used instead of the graphite. This main electrode is provided at its upper part with a screw-threaded part 2i by which it is affixed in the porcelain element ii in suitable relation to the auxiliary electrode 22 carried by the shell or body l2.

From the foregoing it will be apparent that the improved construction affords a spark plug comprising a main electrode having a heat resisting core of low electrical conductivity but with a laminated casing of high electrical conductivity and a high heat resisting character and from which more or less heat is conducted through the central porcelain body to the outer parts of the plug, thus tending to cool said main electrode somewhat and thereby extending its life.

Having thus described my invention I claim and desire to secure by Letters Patent:

1. A spark plug having a main electrode comprising a heat resisting core of low electrical conductivity covered by a laminated heat-resisting covering or casing of high electrical conductivity.

2. A spark plug having a main electrode comprising a heat-resisting core of low electrical conductivity covered by a laminated heat-resisting covering or casing of high electrical conductivity, said laminated covering or casing consisting of a layer of copper next said core and eiicioaed in a layer of silver.

3. A spark plug having a main electrode comprising a heat-resisting'core of low electrical conductivity covered by a laminated heat-resisting covering or casing of high electrical conductivity, said spark plug comprising a non-conducting element and a heat-resisting cement 01. high electrical conductivity and by which said electrode is secured in said element.

4. A spark plug having a main electrode comprising a heat resisting core of low electrical conductivity covered by a laminated heat-resisting covering or casing of high electrical conductivity,

said laminated covering or casing consisting oi. a layer of copper next said core and enclosed in a layer of silver, said spark plug comprising a nonconducting element and a heat-resisting cement of high electrical conductivity and by which said electrode is secured in said element.

5. A spark plug comprising an outer shell or body of a copper alloy, a porcelain element, a

copper alloy nut to secure said porcelain element in said shell or body, and a main electrode having a laminated casing extending through said porcelain element.

6. A spark plug comprising an outer shell or body or copper alloy, a porcelain element, a copper alloy nut to secure said porcelain element in said shell or body, and a main electrode having a laminated casing extending through said porcelain element, said spark plug also comprising a long copper gasket or ferrule interposed between said porcelain element and said outer shell or body.

CHARLES A. XARDELL.

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