| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the failure diagnosis accuracy of the combustor located upstream of the catalyst of the internal combustion engine. SOLUTION: If the catalyst temperature is greater than the combustor temperature when the combustor temperature and the catalyst temperature are compared while the combustor is in operation, the temperature gradientΔT1(= catalyst temperature - combustor temperature)is calculated as the temperature gradient resulting from incomplete combustion (S1 through S4). On the other hand, CO, HC, and H2 concentration inside the mixing chamber of exhaust and secondary air are calculated based on the exhaust air fuel ratio and exhaust flow rate and the secondary air flow rate. From this, the temperature increase gradientΔT2 of the exhaust temperature at complete combustion in the catalyst is calculated. The proportionΔT1/ΔT2 is defined as proportion UBR not burned in the combustor. When UBR is greater than a predetermined value A, failure indicator lamp is indicated as well as storing it as a quantitative diagnosis result of the degree of abnormality (S9 through S12).</p> |
