GB686496A - Improvements in igniter plugs for gas turbine engines - Google Patents

Abstract

686,496. Sparking plugs. GENERAL MOTORS CORPORATION. Feb. 19, 1951 [Feb. 28, 1950], No. 3922/51. Class 7 (iv). In an igniter plug for a gas turbine engine comprising a casing 2, Fig. 1, haying an aperture 10. ,in its wall and an insulator 4, Fig. 2; with a centrally disposed electrode 32 mounted in the casing, the casing and insulator are arranged in spaced relationship along a part of the length of the plug to form an air duct 52 in Communication with the aperture 10 and having converging wall portions adjacent the end thereof to provide a restricted outlet 56, adjacent the spark gap, from the air duct 52; the casing may be cylindrical and have a plurality of inturned tapered electrodes 13, Fig, 1, as well as embodying a mounting flange 6. The insulator 4, Fig. 2, has a enlarged part 18 forming two shoulders 20 and 22 by which it is secured in the plug casing through a connector 14, gaskets being interposed between the shoulders and the casing, the upper one of which is in contact with the lower edge of the connector 14. The upper portion of the insulator 4 is recessed at 30 to accommodate the ignition' lead, not shown, whilst the lower part of the insulation is tapered and spaced from the casing by the cooling air duct 52, which duct communicates at the active end of the plug with the spark gap and at an intermediate point with the radial inlet aperture 10. The centre electrode 32, Fig. 2, has a knurled part 38 engaging the bore in the insulator 4, the lower surface of which is recessed at 34 for cooling purposes; the electrode 32 is connected with a terminal 42 in the upper insulator recess 30 by a conductive element 44. In a modification, the plug casing is formed in two parts which are joined together just above the upper insulator shoulder.