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US 5,207,057 AGranted
Air-fuel ratio control device for an engine
AssigneeToyota Jidosha Kabushiki Kaisha
InventorNobuaki Kayanuma
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AssigneeToyota Jidosha Kabushiki Kaisha
InventorNobuaki Kayanuma
Estimating the term…
An air-fuel ratio control device for an engine having two or more cylinder groups, such as a V-type engine or a horizontally opposed engine, wherein the air-fuel ratio control device controls the air-fuel ratio of cylinder groups in accordance with the output of upstream air-fuel ratio sensors and a downstream air-fuel ratio sensor. The upstream air-fuel ratio sensors are disposed in the individual exhaust passage connected to the respective cylinders upstream of the catalyst converter. The downstream air-fuel ratio sensor is disposed in the common exhaust passage downstream of the catalyst converter. The air-fuel control device usually controls the air-fuel ratios of individual cylinder groups in accordance with the output of the respective upstream air-fuel ratio sensor. When a determination of whether or not the catalyst converter has deteriorated is required, the air-fuel ratio control device controls the air-fuel ratio of all cylinder groups in accordance with the output of either one of upstream air-fuel ratio sensors, whereby the air fuel ratio of the exhaust gas flow into the catalyst converter is changed at a predetermined frequency (period). In this condition, the air-fuel ratio control device determines whether or not the catalyst converter has deteriorated by comparing the outputs of the upstream air-fuel ratio sensor and the downstream air-fuel ratio sensor.
An air-fuel ratio control device for an engine having a plurality of cylinders divided into cylinder groups, said engine comprising, exhaust passages connected to the respective cylinder groups, a common exhaust passage with which said individual exhaust passages are merged, first air-fuel ratio sensors disposed in said individual exhaust passages to detect an air-fuel ratio of the exhaust gas, a second air-fuel ratio sensor disposed in said common exhaust passage to detect an air-fuel ratio of the exhaust gas, and at least one catalyst converter disposed upstream of said second air-fuel ratio sensor and downstream of said first air-fuel ratio sensors, said air-fuel ratio control device comprising:
Dependencies are inferred from the claim text.