Patent ID: 9163539
Filing Date: 2015-10-20
Classification: F01N,F02D,F02M,Y02T

Abstract:
1. A reducing agent supply apparatus comprising: a pump for sucking up and pumping liquid reducing agent stored in a tank; a reducing agent injection valve for injecting the liquid reducing agent to within an exhaust gas passageway of an internal-combustion engine; a reducing agent supply passage for guiding the liquid reducing agent pumped from the pump to the reducing agent injection valve; a reducing agent return passage connected between the reducing agent supply passage and the tank; and a pressure sensor for detecting reducing agent pressure within the reducing agent supply passage, wherein 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, wherein the reducing agent supply apparatus also comprises: a passage throttle valve provided on the reducing agent return passage and having an opening controlled according to a change in an operation amount of the reducing agent injection valve; and a pump controller for feedback-controlling output of the pump based on a difference between the reducing agent pressure and the target pressure, wherein the passage throttle valve is configured to normally open at a predetermined basic opening; when the operation amount of the reducing agent injection valve sharply increases, temporarily decreases the opening of the passage throttle valve; and, when the operation amount of the reducing agent injection valve sharply decreases, temporarily increases the opening of the passage throttle valve.