| 摘要 |
PURPOSE:To raise the heat resistance of a sheathed glow plug as well as reduce the cost of production by forming the projection of a fitting metal for the sheathed tube of a heating tube to be used for preheating of Diesel engine from a heat-resistant metal outer layer and an iron-based alloy inner layer. CONSTITUTION:A glow plug consists of a cylindrical fitting metal 1 with a fitting screw 101 and a heating tube 2. The heating tube 2 is provided with a sheathed metal tube 3 whose tip 31 is closed, a bar-like metal center electrode 4 inserted along the center of the sheathed metal tube 3, and a coiled heating wire 5 connecting between the tip 41 of the center electrode 4 and the tip bottom 30 of the sheathed tube 3 filled with an electrically insulating ceramic powder 6. In this case, in the sheathed tube 3, the projection from the fitting metal 1 is formed of a heat-resistant metal outer layer 32 of Ni- or Co-based alloy and a metal inner layer 33 of an iron-based alloy, whereby attaining the expected purposes. |
