GB627607A - Improvements in or relating to low tension sparking plugs - Google Patents

Abstract

627,607. Sparking plugs. SMITS, W. B. Dec. 4, 1946, Nos. 35963 and 35964. Convention dates, Dec. 14, 1945, and Jan. 26, 1946. [Class 7 (iv)] In a low-tension sparking-plug comprising, in combination, an outer housing, electrodes mounted in the housing and separated from one another by a member of electrically insulating or semi-conductive material on the surface of which the igniting spark is produced, there is provided a, leading-in insulator through which extends a conductor electrically connected to at least one electrode, the remaining electrodes being connected together and to the housing, the electrodes being sintered or fused to one another thus together forming a single unit or insert member which is accommodated in the housing. Mounted in the body 1 of the sparking plug, Figs. 1a, 1b, are annular-outer and central electrodes 2, 3 respectively. These electrodes 2, 3, which are stated to be of a hard heat-proof metal such as manganese steel or the material known by the Registered Trade Mark of " Stellite " or a conductive sinterable material such as steel known by the Registered Trade Mark of " Widia " or tungsten carbide, have an insulating or semiconductive separating member 4 between them. The separating member 4 may be hardened by and joined to the electrodes by sintering or fusing. In a modification, two annular-concentric electrodes are provided around the central electrode ; each annular electrode is insulated from the other and the three electrodes and two separating members are made from sinterable material ; the whole being united by sintering. This unit or insert member is then mounted in the plug body. In a further modification, Figs. 4a, 4b, an insulator or semi-conductor 13 has annular grooves formed on the inner surface in which is placed, in powder form, sinterable metal constituting electrodes 14, 15, that are joined to the member 13 by sintering. Conductors 16, 17, connect the electrodes 14, 15, to the terminal (not shown) and the plug body 18 respectively. The member 13 is provided with a packing member 19, and a heat proof packing material 20, is interposed between these parts so closing the channels through which the electrical conductors 14, 15 are taken. The shape of the electrodes is such that the distance between them is a minimum when measured along the active plug surface. The Specification as open to inspection under Sect. 91 relates also to the insert member being assembled by pressing or melting. This subjectmatter does not appear in the Specification as accepted.