| 摘要 |
<P>PROBLEM TO BE SOLVED: To surely release NOx from an NOx absorbing agent while reducing the amount of added fuel and the amount of energy applied to the fuel. <P>SOLUTION: In a case that NOx is to be released from the NOx absorbing agent in an NOx occlusive reduction type catalyst 24 disposed in an engine exhaust passage, the fuel is added from a fuel adding device 31 so as to make the air fuel ratio of exhaust gas flowing into the NOx absorbing agent temporarily rich. The fuel adding device 31 is designed such that the fuel can be added to the engine while applying voltage to the fuel. In a case that NOx is to be released from the NOx absorbing agent, first, fuel addition with DC voltage application is conducted. In a case that it is judged that the fuel added at that time is not effectively utilized for NOx releasing action and it is judged that the amount of discharged fuel exceeds an allowed upper limit, the amount of energy applied to the fuel is increased and then the fuel addition with DC voltage application is conducted. In a case that it is judged that the fuel added at that time is not effectively utilized for the NOx releasing action, it is switched to fuel addition with superposed voltage application. <P>COPYRIGHT: (C)2009,JPO&INPIT |
