| 摘要 |
PURPOSE:To prevent a heating body from melting and cutting surely and permit the prompt temperature rise thereof by a method wherein a temperature difference between the surface temperature of the glow plug and the temperature of the heating body due to the variation of an electric source voltage as well as the elongation or shortening of a conducting time for the glow plug are permitted to maintain them in proper. CONSTITUTION:The contact 41 of first relay 4 for supplying a large current is inserted into a conducting circuit for the glow plug 3 while the relay 4 is controlled by first timer 6 changing the output time constant thereof in accordance with the input voltage thereof. A current, limited through a current limiting resistor 52, can be supplied to the glow plug 3 through the contact 51 of the second relay 5. The first timer 6 consists of first charging circuit L1, concerning the charging of a capacitor C1 for determining the time constant at all times, the second charging circuit L2, charging the capacitor C1 during a time in which the charging voltage of the capacitor C1 is not satisfying a value determined so as to become a substantially constant ratio with respect to a glow plug impressing voltage Vg, and the third charging circuit L3, charging the capacitor 1 when said voltage Vg is higher than a given value. |
