Patent ID: 8534053
Filing Date: 2013-09-17
Classification: F01N,Y02A,Y02T

Abstract:
1. An exhaust purification apparatus for an internal combustion engine comprising: an NOx catalyst provided in an exhaust system of the internal combustion engine to selectively reduce NOx; a reducing agent inlet provided upstream of the NOx catalyst, through which a urea aqueous solution or ammonia is supplied to the NOx catalyst as a reducing agent; a first NOx sensor provided upstream of the reducing agent inlet and a second NOx sensor provided at an outlet of the NOx catalyst, each of the NOx sensors reacting both to NOx and to ammonia; and a controller configured to: wherein the predetermined temperature region is a temperature region that is equal to or higher than such a temperature that half of the reducing agent added is converted into NOx in a process where a rate at which the reducing agent is converted into NOx increases as the bed temperature of the NOx catalyst increases.