Air/fuel mixture imbalance diagnostic systems and methods
First Claim
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1. An air/fuel imbalance diagnostic system comprising:
- a filtering module that receives an oxygen signal from an oxygen sensor, that selectively samples the oxygen signal, and that generates imbalance data samples using;
a Kalman filter;
estimates of the imbalance data samples generated based on a first matrix having elements that reflect a cyclical nature of imbalance data samples of an engine cycle;
oxygen signal data generated based on samples of the oxygen signal and samples of a reference oxygen signal determined based on an average of a predetermined number of oxygen signal samples; and
estimates of the oxygen signal data generated based on a second matrix having elements that reflect respective contributions of cylinders of a cylinder bank to the oxygen signal;
wherein the oxygen sensor measures oxygen in the exhaust from the cylinders of the cylinder bank;
an imbalance determination module that determines one air/fuel imbalance (AFIM) value for the entire cylinder bank based on a variance of a plurality of the imbalance data samples;
an imbalance diagnostic module that selectively indicates that an AFIM is present in the cylinder bank based on the AFIM value; and
a cylinder identification module that, in response to the imbalance diagnostic module indicating that the AFIM is present in the cylinder bank, attributes the AFIM to one of the cylinders of the cylinder bank.
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Abstract
An air/fuel imbalance (AFIM) diagnostic system comprises a first module, an imbalance determination module, and an imbalance diagnostic module. The first module outputs imbalance data samples based on an oxygen signal provided by an oxygen sensor measuring oxygen in exhaust expelled from cylinders of a cylinder bank. The imbalance determination module determines an AFIM value based on the imbalance data samples. The imbalance diagnostic module selectively diagnoses an AFIM in the cylinder bank based on the AFIM value.
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Citations
14 Claims
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1. An air/fuel imbalance diagnostic system comprising:
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a filtering module that receives an oxygen signal from an oxygen sensor, that selectively samples the oxygen signal, and that generates imbalance data samples using; a Kalman filter; estimates of the imbalance data samples generated based on a first matrix having elements that reflect a cyclical nature of imbalance data samples of an engine cycle; oxygen signal data generated based on samples of the oxygen signal and samples of a reference oxygen signal determined based on an average of a predetermined number of oxygen signal samples; and estimates of the oxygen signal data generated based on a second matrix having elements that reflect respective contributions of cylinders of a cylinder bank to the oxygen signal; wherein the oxygen sensor measures oxygen in the exhaust from the cylinders of the cylinder bank; an imbalance determination module that determines one air/fuel imbalance (AFIM) value for the entire cylinder bank based on a variance of a plurality of the imbalance data samples; an imbalance diagnostic module that selectively indicates that an AFIM is present in the cylinder bank based on the AFIM value; and a cylinder identification module that, in response to the imbalance diagnostic module indicating that the AFIM is present in the cylinder bank, attributes the AFIM to one of the cylinders of the cylinder bank. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An air/fuel imbalance (AFIM) diagnostic method comprising:
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receiving an oxygen signal from an oxygen sensor, wherein the oxygen sensor measures oxygen in exhaust from cylinders of a cylinder bank; selectively sampling the oxygen signal; generating imbalance data samples using; a Kalman filter; estimates of the imbalance data samples generated based on a first matrix having elements that reflect a cyclical nature of imbalance data samples of an engine cycle; oxygen signal data generated based on samples of the oxygen signal and samples of a reference oxygen signal determined based on an average of a predetermined number of oxygen signal samples; and estimates of the oxygen signal data generated based on a second matrix having elements that reflect respective contributions of cylinders of a cylinder bank to the oxygen signal; determining one air/fuel imbalance (AFIM) value for the entire cylinder bank based on a variance of a plurality of the imbalance data samples; selectively indicating that an AFIM is present in the cylinder bank based on the AFIM value; and attributing the AFIM to one of the cylinders of the cylinder bank in response to the indicating that the AFIM is present in the cylinder bank. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification