GB737117A - Improvements in or relating to spark plugs - Google Patents

Abstract

737,117. Sparking plugs. JET IGNITION CO., Inc. Jan. 30, 1953 [Jan. 31, 1952], No. 2709/53. Class 7(4). In a sparking plug comprising a body 11, Fig. 1, containing an ignition chamber 13 open at one end, a pair of electrodes 20, 15c having opposed convex faces axially arranged within the chamber to provide a spark gap, and an electrode head, comprising, for example, a disc 15a, a baffle plate 15b and the earth electrode 15c, closing the chamber 13 and providing one or more passages such as ports 17 in the disc 15a opening into helical channels between the helical baffles on the plate 15b, arranged to cause gas to swirl about the axis of the electrodes and to draw a spark laterally away from the axis, the portion of each channel opening into the chamber is arranged out of line with the associated port 17. Between the lower part of the insulator 10 and the adjacent portion of the body 11 is formed an annular clearance 12 which leads into the cylindrical chamber 13. The electrode 15c which differs in size from the centre electrode 20 is forced into the central opening of the disc 15a and so locates the baffle plate 15b over a stem 15d projecting from the disc 15a ; the latter is then forced into an enlarged bore 16 in the lower end of the body 11. The ports 17 are inclined and have a smaller cross-section than the helical channels. After assembly the disc 15a and plate 15b are copper brazed together. In a modification, the chamber 13, Fig. 4, communicates with the exterior by tangentially disposed bores 26 in the disc 25 which approximate to the turns of a helix each of which open into one of a number of inclined ports 27 of smaller cross-section than the bores 26 ; the ports 27 are extended to comprise pockets 28 which retard the entrance of burnt gases into the chamber 13. In a further modification, the earth electrode of Fig. 1 has a small bore connecting the ignition chamber directly with the engine cylinder. In a final modification, the earth electrode of Fig. 4 has an axial and a joining radial bore that connects the spark gap with the inner end of the ignition chamber.