Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Chemical analysis
Reexamination Certificate
2002-10-11
2004-08-10
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Chemical analysis
C702S024000, C073S023310, C060S276000, C060S274000, C060S285000, C123S435000, C123S677000, C123S678000
Reexamination Certificate
active
06775623
ABSTRACT:
BACKGROUND
This disclosure relates generally to diesel engines and more particularly, to systems and methods for real-time estimation of NOx in exhaust gases generated by the diesel engine.
Current production diesel engines generally do not employ any type of NOx estimation system. By omitting any meaningful real-time NOx estimation, it is possible that the diesel engine will perform sub-optimally due to the fact that other engine operational parameters cannot be dynamically adjusted due to potentially changing NOx levels that occur during the combustion process.
Current production methods of estimating NOx, if employed, are generally based upon a lookup table that can only be generated for a fully calibrated engine, i.e., once the exhaust gas recirculation (EGR), boost, fuel quantity, and timing controllers are designed. When using such techniques, real-time control of NOx is not possible because to control NOx, some of the actuators mentioned above are to be changed, thus changing the original values contained in the look up table. Moreover, the use of lookup table methods primarily involves steady state estimation of NOx. Thus, real-time estimation is not provided by these methods and the use of these methods provides an inherent source of error.
BRIEF SUMMARY
Disclosed herein is a process for providing a real-time estimation of in-cylinder NOx production rates during a combustion process in an internal combustion engine. The process comprises receiving a plurality of input values from a combustion chamber of a cylinder, wherein the input values consist essentially of a mass amount of trapped air in the combustion chamber, a mass amount of trapped fuel in the combustion chamber, a total mass of species generated within a combustion zone as a fraction of total in-cylinder mass, and a correlation value from a lookup table derived from an average NOx temperature of a combustion zone in the combustion chamber; and calculating an output signal from the plurality of input values, wherein the output signal produces a real-time estimate of the NOx production rate from the cylinder.
In accordance with another embodiment, a process for providing a real-time estimation of in-cylinder NOx production rates during a combustion process in an internal combustion engine comprises calculating an average temperature value in a combustion zone of a cylinder combustion chamber; correlating the average temperature value to a correlation value in a look-up table; and estimating the in-cylinder NOx production rate from a calculation including the correlation value, an amount of trapped air in the combustion chamber, an amount of trapped unburned fuel in the combustion chamber, and a total mass of species generated within a combustion zone as a fraction of total in-cylinder mass.
The above described and other features are exemplified by the following figures and detailed description.
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Ali Moataz
Gangopadhyay Anupam
Barlow John
Dougherty Anthony T.
General Motors Corporation
Marra Kathryn A.
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