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US 10,914,253 B2Granted
Internal combustion engine cylinder air-fuel ratio imbalance detection and controls
AssigneeCummins Inc.
InventorsAvra Brahma, Yongsoon Yoon
Life of this patent
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Abstract
A system for detecting and controlling air-fuel ratio imbalance conditions between cylinders of an internal combustion engine having a plurality of cylinders is disclosed.
Claims17
A method for diagnosing an air-fuel ratio (AFR) imbalance condition during operation of an internal combustion engine, comprising:
- determining one or more monitoring conditions are met to enable detection of an AFR imbalance condition;
- in response to one or more enable conditions being met, filling a buffer with a plurality of inputs to use in a sliding discrete fourier transform (SDFT) analysis, the plurality of inputs including a sensed output lambda in an exhaust flow from one or more cylinders of the internal combustion engine;
- determining SDFTs at various frequency components including cycle frequency and its harmonics;
- determining a group energy from the determined SDFTs;
- determining a monitoring parameter in response to a mean value of the group energy around the cycle frequency during the monitoring period;
- and
- comparing the monitoring parameter to a pre-defined threshold and if the monitoring parameter is greater than the threshold, declare a fault relating to the AFR imbalance or otherwise declare an AFR imbalance pass.
4 more elements
An electronic control apparatus for diagnosing an air-fuel ratio (AFR) imbalance condition during operation of an internal combustion engine, comprising:
- an electronic controller configured to:
- determine one or more monitoring conditions are met to enable detection of an AFR imbalance condition of the internal combustion engine;
- in response to one or more enable conditions being met, fill a buffer with a plurality of inputs to use in a sliding discrete fourier transform (SDFT) analysis, the plurality of inputs including a sensed output lambda in an exhaust flow from one or more cylinders of the internal combustion engine;
- determine SDFTs at various frequency components including cycle frequency and its harmonics;
- determine a group energy from the determined SDFTs;
- determine a monitoring parameter in response to a mean value of the group energy around the cycle frequency during the monitoring period;
- and
- compare the monitoring parameter to a pre-defined threshold and in response to the monitoring parameter being greater than the pre-defined threshold, declare a fault relating to the AFR imbalance or otherwise declare an AFR imbalance pass.
5 more elements
Dependencies are inferred from the claim text.