Abstract: A reducing agent supply apparatus includes a pump, a reducing agent injection valve, a reducing agent supply passage, a reducing agent return passage, and a pressure sensor. Injection control of the liquid reducing agent by the reducing agent injection valve is performed while the reducing agent pressure is controlled so as to be maintained at a predetermined target pressure. The reducing agent supply apparatus also includes a passage throttle valve on the reducing agent return passage, a pump control device for feedback-controlling the output of the pump based on the difference between the reducing agent pressure and the target pressure, and a passage throttle valve control device for controlling the opening of the passage throttle valve according to a change in the operation amount of the reducing agent injection valve.

Abstract: A controller and method of a reducing agent injector capable of accurately providing a required amount of ammonia to a reduction catalyst. A controller for controlling energization of an electromagnetic solenoid, including: 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 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 of providing a second current output signal after the first current is provided; a temperature calculator for estimating a temperature within 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 temperature estimated.

Abstract: A reducing agent supply apparatus that can reduce the state of large deviation of the pressure within a reducing agent supply passage from a target pressure and an exhaust gas purification apparatus including such a reducing agent supply apparatus are provided.

Abstract: [Problem] To provide a reducing agent supply apparatus abnormality diagnosis unit that can reduce the limitation on when to perform abnormality diagnosis and on the applicability of abnormality diagnosis to facilitate the implementation of abnormality diagnosis of a reducing agent supply apparatus and to provide the reducing agent supply apparatus.

Abstract: A controller and method of a reducing agent injector capable of accurately providing a required amount of ammonia to a reduction catalyst. A controller for controlling energization of an electromagnetic solenoid, including: 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 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 of providing a second current output signal after the first current is provided; a temperature calculator for estimating a temperature within 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 temperature estimated.