CATALYST CONTROL DEVICE AND CATALYST DETERIORATION DETERMINING DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To enable highly accurate sulfur poisoning restoring control without putting a catalyst bed temperature into an overheated condition even when the degree of deterioration of an exhaust gas purifying catalyst for an internal combustion engine is changed.

SOLUTION: The catalyst base temperature of the exhaust gas purifying catalyst is fluctuated up and down by the intermittent supply of fuel during sulfur poisoning restoring control, and so an amplitude Ampin occurs in an exhaust temperature. The amplitude Ampin is used in detecting the degree of deterioration of the exhaust gas purifying catalyst. When that the deterioration of the exhaust gas purifying catalyst is not in progress is detected in accordance with the amplitude Ampin, a rich time Rt is set to be shorter, thus preventing the maximum value for the catalyst bed temperature from being in an overheat region. When that the deterioration is in progress is determined in accordance with the amplitude Ampin, the rich time Rt is set to be longer, thus preventing the lowering of the catalyst bed temperature and maintaining the efficiency of releasing sulfur components.

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