| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an element electrode of an oxygen sensor arranged on an exhaust passage of an engine from being poisoned by carbon. <P>SOLUTION: When a fuel injection amount (target air-fuel ratio) is increased relative to a stoichiometric amount and the engine is controlled to the rich side, in order to protect the engine or to keep an engine performance, a voltage is applied between an atmospheric side electrode 12 and an exhaust side electrode 13 of the oxygen sensor 1. When the voltage is applied between the electrodes of the oxygen sensor 1 in this way, forced pumping of oxygen ions by the atmospheric side electrode 12 is started, and the pumped oxygen ions are moved toward the exhaust side electrode 13. When oxygen ions are moved to the exhaust side electrode 13, carbon on the electrode surface is burned (oxidized) by catalytic action of the exhaust side electrode (platinum electrode) 13. Thus, poisoning caused by carbon on the exhaust side electrode 13 can be suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT |
