Patent ID: 7892508
Filing Date: 2011-02-22
Classification: F01N,Y02T,Y10S

Abstract:
1. An internal combustion engine exhaust gas purification apparatus, comprising: a NOx storage-reduction catalyst unit provided in an exhaust gas passage; a NOx selective reduction catalyst unit provided downstream of the NOx storage-reduction catalyst unit in the exhaust gas passage; an urea injector provided upstream of the NOx storage-reduction catalyst unit to inject urea into the exhaust gas passage; and an urea injection controller that prohibits execution of urea injection from the urea injector if at least one of a temperature of the NOx storage-reduction catalyst unit and a temperature of the NOx selective reduction catalyst unit is equal to or lower than a reference temperature, wherein the reference temperature corresponds to a catalyst temperature at and below which cyanic acid produced from urea is not converted into ammonia.