| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve fuel economy by maximizing the frequency of lean burn execution while preventing any degradation in quality of a catalyst. SOLUTION: If a lean burn permission flag FCAT for high catalyst temperature is '0' that prohibits a lean burn operation, a catalyst temperature integrated value TCATSUM is compared with a set value KTCATSOK (S122). If the TCATSUM is found not less than the set value KTCATSOK, the flag FCAT is set to '1' (S123). If the flag FCAT is '1' that permits a lean burn operation, the catalyst temperature integrated value TCATSUM is compared with another set value KTCATSNG (S124). If the TCATSUM is found not less than the set value KTCATSNG, the flag FCAT is reset to '0' to prohibit a lean burn operation for the purpose of protecting the catalyst (S125). When the catalyst temperature exceeds its maximum possible temperature for continuous use, the lean burn operation is prohibited or permitted alternately depending on the value of the high-catalyst-temperature lean burn permission flag FCAT.</p> |
