Abnormality diagnosis device and control system for internal combustion engine
AssigneeDenso Corporation
InventorKuniaki Ueda
Life of this patent
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Abstract
An exhaust gas discharged from a combustion chamber of each cylinder flows near an air-fuel ratio sensor via a junction. An ECU estimates an air-fuel ratio of each cylinder based upon a sensing value of an air-fuel ratio sensor. When a variation in the air-fuel ratio among the cylinders is equal to or greater than a predetermined value, the ECU determines that an abnormality exists in the air-fuel ratio. When a quantity of the exhaust gas discharged from each cylinder is less than another predetermined value, an intake air quantity is increased and ignition timing is delayed before the determination of presence or absence of the abnormality.
Claims12
An abnormality diagnosis device of a multi-cylinder internal combustion engine having a junction where exhaust gases discharged respectively from a plurality of cylinders converge, the abnormality diagnosis device comprising:
- an air-fuel ratio sensing means provided downstream of the junction for sensing an air-fuel ratio of the exhaust gas;
- a diagnosing means for diagnosing presence or absence of an abnormality in an individual air-fuel ratio of each cylinder based upon a sensing value of the air-fuel ratio sensing means;
- a determining means for determining whether a quantity of the exhaust gas discharged from each cylinder per exhaust stroke is equal to or greater than a first predetermined value;
- and
- a prohibiting means for prohibiting the diagnosis when the determining means determines that the quantity of the exhaust gas is less than the first predetermined value.
A control system of a multi-cylinder internal combustion engine having a junction where exhaust gases discharged respectively from a plurality of cylinders converge, the control system comprising:
- an abnormality diagnosis device including an air-fuel ratio sensing means provided downstream of the junction for sensing an air-fuel ratio of the exhaust gas, a diagnosing means for diagnosing presence or absence of an abnormality in an individual air-fuel ratio of each cylinder based upon a sensing value of the air-fuel ratio sensing means, a determining means for determining whether a quantity of the exhaust gas discharged from each cylinder per exhaust stroke is equal to or greater than a first predetermined value, and a prohibiting means for prohibiting the diagnosis when the determining means determines that the quantity of the exhaust gas is less than the first predetermined value;
- and
- injectors for supplying fuel to the plurality of cylinders respectively.
Dependencies are inferred from the claim text.