Patent ID: 8171781
Filing Date: 2012-05-08
Classification: F01N,Y02T

Abstract:
1. An abnormality diagnosis apparatus for an NOx catalyst, comprising: NOx catalyst provided in an exhaust passage of an internal-combustion engine; measurement means for measuring an index value regarding an NOx clarification capacity of the NOx catalyst; and abnormality determination means for determining an abnormality of the NOx catalyst based on an index value measured by the measurement means at a timing at which the NOx catalyst has a relatively-low activation level and an index value measured by the measurement means at a timing at which the NOx catalyst has a relatively-high activation level, wherein, the timing at which the NOx catalyst has a relatively-low activation level consists of a first timing, the timing at which the NOx catalyst has a relatively-high activation level consists of a second timing having a higher catalyst activation level than that of the first timing and a third timing having a higher catalyst activation level than that of the second timing, and the abnormality determination means determines, when a change amount between an index value measured at the first timing and an index value measured at the second timing is equal to or lower than a predetermined value, an abnormality of the NOx catalyst based on a change amount between the index value measured at the first timing and an index value measured at the third timing.