GB749382A - Improvements in or relating to ignition plugs - Google Patents

Abstract

749,382. Sparking plugs. K.L.G. SPARKING PLUGS, Ltd. July 8. 1954 [June 10, 1953], No. 16023/53. Class 7(4) In a sparking plug capable of operating in a temperature of about 1200‹C. comprising a metal carrier 18, Fig. 1. a ceramic insulator 10, a pair of electrodes 14, 15 in the insulator, the electrodes being of platinum or platinum alloy, which is capable of working at the required temperature, the operative electrode ends and the adjacent part of the insulator are the only parts of the plug, which, in operation are exposed to the above temperature: The cylindrical alumina insulator 10 houses the two parallel electrodes wires 14, 15 that extend to the active face of the insulator, which face is provided with a coating of semi-conducting material as disclosed in Specification 724,016. In a modification, the insulator 19 Fig. 2, which encloses a central electrode wire 22, is formed with an annular recess 23 that is occupied by a loop 27 of the second electrode wire, the remainder of the wire lying in a surface channel 24 which extends from the recess to the end of .the insulator that is located in the carrier 18. The semi-conducting coating may be omitted and the ends of the wires may be either flush with the active end of the insulator giving a fixed gap or protrude therefrom to enable the air gap to be adjusted by bending the electrode ends.