Patent ID: 6843218

Claim:
A glow plug energization control apparatus for controlling energization from a battery to a glow plug having a resistance heater installed in an engine when a key switch is put in an on position or a start position, the glow plug energization control apparatus comprising: a pre-glow unit for controlling the energization to the glow plug to quickly raise temperature of the resistance heater when the key switch is put in the on position; an upkeep glow unit for calculating a duty ratio Dh of a voltage waveform applied to the glow plug on the basis of a voltage value applied to the glow plug from the battery subsequently to the energization control performed by the pre-glow unit and for performing PWM control for the energization to the glow plug according to the duty ratio Dh; a cranking glow unit for calculating, in a period of a cranking started by putting the key switch in the start position during the energization control performed by the upkeep glow unit, a duty ratio Dk of a voltage waveform applied to the glow plug on the basis of a voltage value applied to the glow plug from the battery and for performing PWM control for the energization to the glow plug according to the duty ratio Dk larger than a virtual duty ratio Dhh calculated by the upkeep glow unit when it is assumed that the voltage value of the battery in a control period of the upkeep glow unit is equal to the voltage value of the battery in a control period of the cranking glow unit; and an after starting glow unit for, after the engine is started, supplying an electric power, which is lower than an electric power supplied to the glow plug by the pre-glow unit, to the glow plug to realize stable heating of the resistance heater.