Cylinder abnormality diagnosis unit of internal combustion engine and controller of internal combustion engine
First Claim
1. A cylinder abnormality diagnosis apparatus of an internal combustion engine, comprising:
- an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas which is disposed in an exhaust confluent portion where the exhaust gases from a plurality of cylinders of the internal combustion engine merge with each other;
an air-fuel ratio estimation means for performing a cylinder air-fuel ratio estimation of estimating an air-fuel ratio of each cylinder based on a detection value of the air-fuel ratio sensor;
an abnormality diagnosis means for performing a cylinder abnormality diagnosis of determining whether each cylinder is abnormal based on an estimate result of the cylinder air-fuel ratio estimation; and
a determination means for determining whether or not an operating state of the internal combustion engine is within a specified operating range in which an estimate accuracy of the cylinder air-fuel ratio estimation increases, whereinwhen it is determined by the determination means that the operating state of the internal combustion engine is within the specified operating range, the abnormality diagnosis means performs the cylinder abnormality diagnosis.
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Accused Products
Abstract
It is determined whether an engine operating state is within a specified operating range. When the engine operating state is within the specified operating range, the air-fuel ratio of an i-th cylinder is estimated based on the detection value of the air-fuel ratio sensor, and a cylinder deviation, which is the deviation of an estimated air-fuel ratio from a reference air-fuel ratio, is computed. When this cylinder deviation becomes larger than a specified determination value, the processing of incrementing the count value of an abnormality counter is started at a point in time when a specified delay time elapses after the cylinder deviation becomes larger than the specified determination value. At a point in time when the count value of the abnormality counter becomes larger than a specified abnormality determination value, it is determined that the air-fuel ratio of the i-th cylinder is abnormal.
24 Citations
12 Claims
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1. A cylinder abnormality diagnosis apparatus of an internal combustion engine, comprising:
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an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas which is disposed in an exhaust confluent portion where the exhaust gases from a plurality of cylinders of the internal combustion engine merge with each other; an air-fuel ratio estimation means for performing a cylinder air-fuel ratio estimation of estimating an air-fuel ratio of each cylinder based on a detection value of the air-fuel ratio sensor; an abnormality diagnosis means for performing a cylinder abnormality diagnosis of determining whether each cylinder is abnormal based on an estimate result of the cylinder air-fuel ratio estimation; and a determination means for determining whether or not an operating state of the internal combustion engine is within a specified operating range in which an estimate accuracy of the cylinder air-fuel ratio estimation increases, wherein when it is determined by the determination means that the operating state of the internal combustion engine is within the specified operating range, the abnormality diagnosis means performs the cylinder abnormality diagnosis. - View Dependent Claims (2, 3, 4, 5)
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6. A controller of an internal combustion engine comprising:
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an air-fuel ratio sensor disposed in an exhaust confluent portion where exhaust gases from a plurality of cylinders of the internal combustion engine merge with each other, a sensor deterioration detection means for detecting a degree of deterioration of responsivity of the air-fuel sensor in a high load range of the internal combustion engine; a correction gain learning means for learning a correction gain relating to a decrease in an output of the air-fuel ratio sensor based on the degree of deterioration of responsivity of the air-fuel ratio sensor that is detected by the sensor deterioration detection means; and an air-fuel ratio correction means for correcting an estimated value of the air-fuel ratio of each cylinder by the use of the correction gain learned by the correction gain learning means. - View Dependent Claims (8, 9)
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7. A controller of an internal combustion engine comprising:
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an air-fuel ratio sensor disposed in an exhaust confluent portion where exhaust gases from a plurality of cylinders of the internal combustion engine merge with each other; a sensor deterioration detection means for detecting a degree of deterioration of responsivity of the air-fuel sensor for each of a plurality of learning ranges divided according to an operating state of the internal combustion engine; a correction gain learning means for learning a correction gain relating to a decrease in an output of the air-fuel ratio sensor based on the degree of deterioration of responsivity of the air-fuel ratio sensor that is detected for each of the learning ranges by the sensor deterioration detection means; and an air-fuel ratio correction means for correcting an estimated value of the air-fuel ratio of each cylinder by the use of the correction gain learned for each of the learning ranges by the correction gain learning means.
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10. A controller of an internal combustion engine comprising:
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an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas which is disposed in an exhaust confluent portion where the exhaust gases from a plurality of cylinders of the internal combustion engine merge with each other; an air-fuel ratio estimation means for estimating an air-fuel ratio of each cylinder based on a detection value of the air-fuel ratio sensor; a correction means for correcting an estimated air-fuel ratio of each cylinder that is estimated by the air-fuel ratio estimation means according to an operating state of the internal combustion engine; and an air-fuel ratio control means for controlling an air-fuel ratio of each cylinder based on an estimated air-fuel ratio of each cylinder that is corrected by the correction means. - View Dependent Claims (11, 12)
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Specification