Abstract: A heating-controller controls an electric power supply from a battery to a urea-water heater based on a voltage of the battery detected by a voltage detector and an engine-state of an internal combustion engine obtained by an engine-state detector. When a voltage of the battery is low or when the internal combustion engine stops, the heating-controller prohibits the electric power supply from the battery to the urea-water heater. A urea-water adding device can avoid an excess decrease of a battery power by intermittently energizing the urea-water heater according to the engine-state of an internal combustion engine and the battery voltage VB.

Abstract: A control portion sets a total injection amount of a urea water injected from an injector to an exhaust gas, and controls to open or close the injector based on the injection amount. An injection-amount correcting portion estimates an injection characteristic of the injector from an injection-amount difference between the total injection amount and a decreased amount of the urea water in a tank, and corrects a command value of a control signal outputted to the injector based on the injection characteristic. Therefore, the injection amount is corrected by considering the individual differences or the age-related deterioration.

Abstract: A heating-controller controls an electric power supply from a battery to a urea-water heater based on a voltage of the battery detected by a voltage detector and an engine-state of an internal combustion engine obtained by an engine-state detector. When a voltage of the battery is low or when the internal combustion engine stops, the heating-controller prohibits the electric power supply from the battery to the urea-water heater. A urea-water adding device can avoid an excess decrease of a battery power by intermittently energizing the urea-water heater according to the engine-state of an internal combustion engine and the battery voltage VB.

Abstract: A control portion sets a total injection amount of a urea water injected from an injector to an exhaust gas, and controls to open or close the injector based on the injection amount. An injection-amount correcting portion estimates an injection characteristic of the injector from an injection-amount difference between the total injection amount and a decreased amount of the urea water in a tank, and corrects a command value of a control signal outputted to the injector based on the injection characteristic. Therefore, the injection amount is corrected by considering the individual differences or the age-related deterioration.