Patent ID: 8793979

Claim:
A reducing agent injector controller for controlling a reducing agent injector that injects reducing agent into an exhaust gas passageway of an internal combustion engine by controlling ON/OFF of a switching device to control energization of an electromagnetic solenoid, the controller comprising: a target injection amount calculator for calculating a target injection amount of the reducing agent; a first current output signal calculator for calculating the duration of providing a first current output signal for generating a first current to be provided to the electromagnetic solenoid at the start of injection and calculating the DUTY ratio of the first current output signal; a second current output signal calculator for calculating the DUTY ratio representing the duration of providing a second current output signal for generating a second current to be provided after the first current is provided; a temperature calculator for estimating a given type of temperature within the reducing agent injector, the estimated given type of temperature being a temperature of a sliding part of a valve needle of the reducing agent injector; and an output signal corrector for correcting at least one of the first current output signal and the second current output signal based on the given type of temperature estimated; wherein when the output signal corrector corrects the second current output signal, the output signal corrector corrects the duration of providing the second current output signal based on the temperature of the sliding part; wherein one of the first current output signal and the corrected first current output signal is provided to the electromagnetic solenoid, and one of the second current output signal and the corrected second current output signal is provided to the to the electromagnetic solenoid.