| 摘要 |
<p>PURPOSE:To prevent deterioration of a battery by providing an energization control means which is constituted to carry a current to an electric heater when the degree of catalyst purifying performance is below a necessary value and stop current-carrying to the electric heater when the degree of catalyst purifying performance exceeds a necessary value. CONSTITUTION:An exhaust emission control device for an internal combustion engine comprises an air-fuel ratio fluctuation comparing means 19 to compare the air-fuel ratio fluctuation of a place situated upper stream from a catalyst 12 and that of a place situated downstream therefrom; a degree of deterioration of catalyst deciding means 20 to decide the degree of deterioration of of a catalyst based on the comparing result; and a degree of purification deciding means 24 to decide the degree of catalyst purifying performance by a necessary current-carrying time deciding means 23 to decide an energizing time necessary to an electric heater 13 and an air-fuel fluctuation comparing means 19 from a detecting voltage value of a battery, an engine cooling water temperature, and a decision value of the degree of deterioration of a catalyst. Based on information of the deciding means, energization to the electric heater 13 is controlled by an energization control means 25. This constitution eliminates a fear of a catalyst being heated to temperature more than a necessary temperature from the degree of purification performance of an electric heating type catalyst and prevents deterioration of the electric type heating catalyst.</p> |
