Apparatus and method for detecting failure of exhaust gas sensor
First Claim
1. An apparatus for detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold of an engine, the apparatus comprising a control unit configured to:
- select from outputs of the exhaust gas sensor a first output having a local maximum amplitude value;
select from outputs of an air-fuel sensor a second output having a local maximum amplitude value, the air fuel ratio sensor disposed upstream of the catalyst converter;
determine a ratio between the local maximum amplitude value of the first output and the local maximum amplitude value of the second output; and
detect the failure of the exhaust gas sensor based on the ratio.
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Accused Products
Abstract
An apparatus for detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold is provided. The apparatus comprises a control unit. The control unit determines a ratio between an amplitude value of a first output of the exhaust gas sensor and an amplitude value of a second output of an air-fuel ratio sensor. The air fuel ratio sensor disposed upstream of the catalyst converter. The control unit detects a failure of the exhaust gas sensor based on the ratio. In one embodiment, a statistical process using a successive least squares method is applied to the ratio. The control unit detects a failure of the exhaust gas sensor based on the statistically processed ratio. In another embodiment, the statistical process is applied to both the output of the exhaust gas sensor and the output of the air-fuel ratio sensor. The control unit detects a failure of the exhaust gas sensor based on a ratio between the statistically processed outputs of the exhaust gas sensor and the air-fuel ratio sensor.
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Citations
38 Claims
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1. An apparatus for detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold of an engine, the apparatus comprising a control unit configured to:
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select from outputs of the exhaust gas sensor a first output having a local maximum amplitude value;
select from outputs of an air-fuel sensor a second output having a local maximum amplitude value, the air fuel ratio sensor disposed upstream of the catalyst converter;
determine a ratio between the local maximum amplitude value of the first output and the local maximum amplitude value of the second output; and
detect the failure of the exhaust gas sensor based on the ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold of an engine, the apparatus comprising a control unit configured to:
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determine a ratio between an amplitude value of a first output of the exhaust gas sensor and an amplitude value of a second output of an air-fuel ratio sensor, the air-fuel ratio sensor disposed upstream of the catalyst converter; and
detect the failure of the exhaust gas sensor based on the ratio, wherein the control unit is further configured to sample outputs of the exhaust gas sensor;
identify from the samples obtained from the exhaust gas sensor a first sample having a local maximum amplitude value;
select samples in the vicinity of the first sample;
sample outputs of the air-fuel ratio sensor;
identify from the samples obtained from the air-fuel sensor a second sample having a local maximum amplitude value;
select samples in the vicinity of the second sample; and
determine the ratio based on a first set of samples and a second set of samples, the first set of samples including the first sample and the selected samples in the vicinity of the first sample, the second set of samples including the second sample and the selected samples in the vicinity of the second sample. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold of an engine, the method comprising the steps of:
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selecting from outputs of the exhaust gas sensor a first output having a local maximum amplitude value;
selecting from outputs of an air-fuel sensor a second output having a local maximum amplitude value, the air fuel ratio sensor disposed upstream of the catalyst converter;
determining a ratio between the local maximum amplitude value of the first output and the local maximum amplitude value of the second output; and
detecting the failure of the exhaust gas sensor based on the ratio. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A method for detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold of an engine, the method comprising the steps of:
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determining a ratio between an amplitude value of a first output of the exhaust gas sensor and an amplitude value of a second output of an air-fuel ratio sensor, the air-fuel ratio sensor disposed upstream of the catalyst converter; and
detecting the failure of the exhaust gas sensor based on the ratio, wherein the step of determining a ratio further comprises the steps of sampling outputs of the exhaust gas sensor;
identifying from the samples obtained from the exhaust gas sensor a first sample having a local maximum amplitude value;
selecting samples in the vicinity of the first sample;
sampling outputs of the air-fuel ratio sensor;
identifying from the samples obtained from the air-fuel sensor a second sample having a local maximum amplitude value; and
selecting samples in the vicinity of the second sample; and
determining the ratio based on a first set of samples and a second set of samples, the first set of samples including the first sample and the selected samples in the vicinity of the first sample, the second set of samples including the second sample and the selected samples in the vicinity of the second sample.
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29. A computer program stored on a computer readable medium for use in detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold of an engine, the computer program comprising:
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program code for selecting from outputs of the exhaust gas sensor a first output having a local maximum amplitude value;
program code for selecting from outputs of an air-fuel sensor a second output having a local maximum amplitude value, the air fuel ratio sensor disposed upstream of the catalyst converter;
program code for determining a ratio between the local maximum amplitude value of the first output and the local maximum amplitude value of the second output; and
program code for detecting the failure of the exhaust gas sensor based on the ratio. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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38. A computer program stored on a computer readable medium for use in detecting a failure of an exhaust gas sensor disposed downstream of a catalyst converter in an exhaust manifold of an engine, the computer program comprising:
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program code for determining a ratio between an amplitude value of a first output of the exhaust gas sensor and an amplitude value of a second output of an air-fuel ratio sensor, the air-fuel ratio sensor disposed upstream of the catalyst converter; and
program code for detecting the failure of the exhaust gas sensor based on the ratio, wherein program code for determining a ratio further includes program code for sampling outputs of the exhaust gas sensor;
program code for identifying from the samples obtained from the exhaust gas sensor a first sample having a local maximum amplitude value;
program code for selecting samples in the vicinity of the first sample;
program code for sampling outputs of the air-fuel ratio sensor;
program code for identifying from the samples obtained from the air-fuel sensor a second sample having a local maximum amplitude value;
program code for selecting samples in the vicinity of the second sample; and
program code for determining the ratio based on a first set of samples and a second set of samples, the first set of samples including the first sample and the selected samples in the vicinity of the first sample, the second set of samples including the second sample and the selected samples in the vicinity of the second sample.
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Specification