Patent ID: 7319208

Claim:
A control device for a glow plug, the glow plug comprising a resistance heater extending axially of the glow plug, including a resistive heating element that has a ratio R1000/R20 of electrical resistance R1000 at 1000° C. to electrical resistance R20 at 20° C. of 6 or larger and being mounted in an engine block with a front end portion of the resistance heater and at least part of the resistive heating element protrudingly located in an engine combustion chamber, the control device being configured to control energization of the resistance heater in a steady control mode to adjust electrical power supplied to the resistance heater in such a manner as to keep a resistance of the resistance heater within a predetermined range, the resistance heater including a cylindrical sheath tube having a closed front end to which the resistive heating element is connected and an inrush current limiting resistor connected in series with the resistive heating element so as to reduce an inrush current through the resistive heating element, and the inrush current limiting resistor having a smaller ratio R1000/R20 of electrical resistance R1000 at 1000° C. to electrical resistance R20 at 20° C. than that of the resistive heating element.