| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control system of an engine capable of supplying a proper quantity of urea-water solution, by accurately estimating a ratio of NO<SB POS="POST">2</SB>/NOx. <P>SOLUTION: This exhaust emission control system includes: a PM (particulate matter) deposit quantity estimating section 82 for calculating an estimate QPM of a PM deposit quantity in a DPF (diesel particulate filter), an NOx quantity estimating section 81 for calculating an estimate of an NOx quantity in exhaust gas between the DPF and a selective reduction catalyst within an exhaust pipe; an exhaust temperature sensor for detecting the exhaust temperature T<SB POS="POST">DPF</SB>on the downstream side of the DPF; an NO<SB POS="POST">2</SB>/NOx ratio estimating section 83 for calculating an estimate RNO2 of the NO<SB POS="POST">2</SB>/NOx ratio of the exhaust gas between the DPF and the selective reduction catalyst within an exhaust system based on an estimate QPM of the PM deposit quantity, an estimate NOX<SB POS="POST">HAT</SB>of the NOx quantity and the exhaust temperature T<SB POS="POST">DPF</SB>; and an injection quantity determining section 84 for determining a urea-water solution injection quantity by a urea-water solution injection unit based on the estimate NOX<SB POS="POST">HAT</SB>of the NOx quantity and the estimate RNO2 of the NO<SB POS="POST">2</SB>/NOx ratio. <P>COPYRIGHT: (C)2012,JPO&INPIT |
