| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the electric power controlling method for a discharge type exhaust emission control device. SOLUTION: In this exhaust emission control device, the exhaust gas of an internal combustion engine is purified by passing to a flow passage formed between at least a pair of discharge electrodes and applying AC high voltage between the discharge electrodes. In the device, all of pulse of the AC high voltage are applied between the discharge electrodes in high loading where an exhaust gas flow rate is maximum. In middle/low loading where the exhaust gas flow rate is lower than that of high loading, the pulse of the AC high voltage is intermittently thinned out in accordance with the exhaust gas flow rate. In such a way, power supply is lowered in accordance with the exhaust gas flow rate without lowering the applied voltage (discharge capacity) between the discharge electrodes. In the case when the exhaust gas flow rate is low, not only the probability that the exhaust gas meets with the discharge but also the exhaust gas purifying efficiency are not changed so much even if the generating ratio of the discharge is lowered by thinning out the pulse of the AC high voltage since the flow velocity of the exhaust gas passing between the discharge electrodes is lowered.</p> |
