GB547119A - Improvements relating to sparking plugs for internal combustion engines - Google Patents

Abstract

547,119. Sparking-plugs. LODGE PLUGS, Ltd., HOPPS, B., and SMITHELLS, C. J. July 15, 1941, No. 8929. [Class 7 (iv)] A ceramic insulator a has a central bore b and a metal core e within the bore and in intimate contact for a substantial part of its length with the surface of the bore, this contact being effected by expansion of the core under pressure. preferably while softened by heat at a temperature below its melting point. In one form, Fig. 1, the insulator is fitted with a sparking tip c of platinum or platinum alloy, having a shoulder d, and powdered copper e is rammed into the bore b and the assembly is heated to 950‹C. in a reducing atmosphere while the core is subjected to pressure. In a modification, Fig. 3, a silver rod e is bored to receive the inner end of the sparking tip c and a bead f of conductive sealing material, such as a mixture of glass and graphite or copper, is superposed; the assembly is heated to about 900‹C and a pressure of about 2 tons per square inch applied by a plunger. The sparking tip may be secured to one end of the silver rod e before the latter is inserted in the insulator. In a further form, Fig. 7, the silver core e is tubular and a nickel electrode c has a head g abutting on the upper end of the core ; expansion of the heated core is effected by endwise pressure. In the forms shown in Figs. 1 and 7, a seal such as f, Fig. 3, may be employed. Specification 534,248 is referred to in the Provisional Specification.