| 摘要 |
PURPOSE:To miniaturize a heating wire coil, to prevent the obstruction of the formation of vortex flow in a combustion chamber approximately and to increase mechanical strength against vibration, impact, etc. by using a W alloy wire rod in a specific composition having specific resistance larger than that of a pure W wire rod, which has been employed, as a heating wire for a ceramic heater. CONSTITUTION:A hating wire coil 12 is miniaturized by using a W alloy, in which at least one kind or more of rhenium (Re), thorium (Th) or zirconium (Zr) are added to W, as a wire rod having specific resistance (10muOMEGA-cm<3> or more) larger than that (5.0muOMEGA-cm<3>) of a pure tungsten (W) wire rod. Accordingly, a heater section 10' is formed in small size so that an outer diameter D (a long diameter on the heater section, a section thereof does not take a true circle but takes a shape similar to an oval) extends over approximately 4.0mm. or less and projecting size (l) from the nose surface of a metallic outer cylinder 11 treble or less as large as the outer diameter D. |
