| 摘要 |
PURPOSE:To make a current value subject to on-off control smaller and a control circuit into being simplified in structure, by connecting a heating unit elemet being small in a resistance thermal coefficient to a resistance element being large in that coefficient in series, while lowering an upward rate in time of a rise in heating temperature. CONSTITUTION:A glow plug 3 is connected with a heating unit element 3a being small in a resistance thermal coefficient and a resistor element 3b being extremely large in a positive resistance thermal coefficient in series. At normal temperature, since a resistance value of the resistor element 3b is small, for example, becoming about 0.5OMEGA in the value, but when a heating part comes to a temperature of 900 deg.C or so, the resistance value comes to about 0.8OMEGA, that is, in proportion as a temperature rise in the heating part, the resistance value grows large whereby the upward trend is weakened with the temperature rise, coming into saturation. With this constitution, building up in the glow plug can be more speedier even if a large current is made to flow into the plug and, what is more, there can get through with one transistor element alone, thus a driving circuit can be simplified in structure. |
