GB479606A - Spark plug shielding apparatus - Google Patents

Abstract

479,606. Two-part couplings. GENERAL MOTORS CORPORATION. Aug. 14, 1936, No. 22413. Convention date, Aug. 21, 1935. [Class 38 (i)] [Also in Group XXVII] Slotted shields 26 for suppressing high frequency emission from engine ignition systems extend to the conductor harness and are formed rigidly with the sparking plug casing 14. They may consist of materials of different thermal conductivity, part being of stainless steel or nickel-chrome and the remainder of copper or aluminium. A skeleton of hard material, such as steel, may be used around which softer metal is diecast. Six bars and slots of equal total width constitute the best shield. Slots may be formed at the junction of the plug casing proper with the shield, or in the cap member supporting the cable harness in the end of the shield. The outer part of the plug insulation is surrounded by an insulating sleeve 32 which also encloses a flanged sleeve 33 screwing on to the retaining cap 25. A further insulating sleeve 35 lies within the sleeve 32 and bears on the disc 36. In a modification, Fig. 8, a cap 61 mounted on the outer end of the casing 60 is integral with a metal sheath 63 lined with insulation 64 which is in threaded engagement with the outer part of the plug insulation. Metal bosses 103 in the side of a cup 100, 104 are engaged by the spring - pressed stem 101. The conduit 40 may be straight, curved or angular: It may be provided with heatdissipating ribs, and the sheathing 51, Fig. 4, may be supported on a disc 49 clamped between the layers of mica insulation at the outer part of the plug. Two other coupling arrangements are shown in Figs. 3 and 6.