| 摘要 |
During running, should no torque be required, engine ignition is cut and purging is initiated. Preferred features: During running, efficiency of the (three-way) adsorption catalyst (6) is evaluated, with respect to NOx emission reduction. A table gives catalyst NOx saturation in terms of catalyst temperature. Purging is initiated when this efficiency falls below a set threshold, with the ignition cut as described. Once efficiency exceeds a set value in terms of measured catalyst temperature, purging is stopped. NOx saturation is evaluated, commencing by measuring the current NOx storage during weak running. A table gives the maximum quantity which can be absorbed as a function of catalyst temperature and quantity of NOx in the exhaust gases. The quantity stored is drawn from a further table linking exhaust and engine NOx output in terms of catalyst temperature. During purging, NOx decrement is tracked. Purging is stopped when the catalyst efficiency rises above a threshold predetermined from successive purges. Catalyst efficiency is measured by comparison between engine (1) and exhaust outlet measurements of NOx. Purging is stopped when engine ignition is on. Mixture enrichment results from fuel injection under pressure. With indirectly injected engines, enrichment takes place in the combustion chamber. With directly injected engines, enrichment takes place in the combustion chamber or the exhaust. |
