| 摘要 |
PURPOSE:To enable to quickly and smoothly red-heat from the tip part of a sheathed heating element so as to rapidly attain to the ignition temperature by a method wherein the gap between the coiled heating element and the inner wall surface of a metal tubing is so arranged as to gradually become smaller from the rear end to near the tip of the metal tubing. CONSTITUTION:A bar insulator 5 is moulded to the size, which can be housed in the spece inside the coil of the heating element 2, with the same material as powdered insulator 3 to be filled among the coiled heating element, for example with powdered magnesia, and yet the hardness of the moulded insulator 5 is so controlled as to gradually become harder from the rear end of an electrode shaft to near the bottom 4 of the metal tubing 1. Said bar insulator 5 is housed in the coiled heating element 2. Then the element 2 is put in the metal tubing 1 and filled with the powdered insulator 3 thereamong in the metal tubing 1. After that, said metal tubing 1 is subjected to the swaging so as to be formed as the sheathed glow plug. |
