Air-fuel ratio control apparatus for engine
OwnerYasuo Hirata, Hisashi Iida +1inventors
InventorsYasuo Hirata, Hisashi Iida, Noriaki Ikemoto
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Abstract
An engine has an upstream catalyst and a downstream catalyst in an exhaust system. An air-fuel ratio control apparatus has an oxygen sensor that outputs signal indicative of an oxygen storage amount in the downstream catalyst. The apparatus has an air supply device for supplying the air into upstream the downstream catalyst. When the signal of the oxygen sensor indicates a shortage of the oxygen storage amount in the downstream catalyst, the air supply device is activated to supply the air to the downstream catalyst. Thus, the downstream catalyst can recover the oxygen storage amount sufficient to keep its catalysis.
Claims9
An air-fuel ratio control apparatus for an engine comprising:
- a first catalyst disposed in an exhaust passage of the engine;
- a second catalyst disposed in the exhaust passage downstream the first catalyst;
- an air-fuel ratio sensor disposed in the exhaust passage upstream the first catalyst;
- second catalyst condition detecting means for detecting a condition of the second catalyst;
- feedback control means for controlling an air-fuel ratio to maintain a detected air-fuel ratio by the air-fuel ratio sensor in a target air-fuel ratio by using a feedback control method, the target air fuel ratio being set in accordance with an output of the second catalyst condition detecting means;
- and
- oxygen storage recovery means for recovering an oxygen storage in the second catalyst when the second catalyst condition detecting means outputs a predetermined level.
Dependencies are inferred from the claim text.