An improved glow plug having a resistive surface film heater.

摘要

A glow plug (10) having a hollow cylindrical metal shell (12), an axial electrical terminal (36), and a heater member (20) protruding externally from the shell. The heater member (20) has a surface film heater element (24) disposed on at least one surface of an electrically nonconductive cylindrical substrate (22). Electrical connections between the heater element (24), the shell and the axial electrode are made by conductive surface films (56, 58). A first conductive surface film (56) disposed on the external surface of the cylindrical substrate (22) makes electrical contact with the shell (12). A second conductive surface film (58) disposed on the internal surface of the cylindrical substrate (22) makes electrical contact with the axial electrical terminal (36). The heating element (24) is preferably a transition metal surface film which catalytically reacts with the air/fuel mixture to enhance combustion at lower temperatures. The thermal response time of the surface film heater element (24) from ambient to an operating temperature exceeding 800 is less than 5 seconds.