Advanced engine control

Abstract

A method for controlling an internal combustion engine to maintain a predetermined combustion efficiency, comprises: measuring the concentration of CO in an engine-out emission; determining whether the measured concentration of CO is above or below a target CO concentration for the engine under the operating conditions in use; and if the concentration of CO is above the target CO concentration, adjusting one or more engine and / or combustion parameters so as to reduce the concentration of CO in the engine-out emission, and if the concentration of CO is below the target CO concentration, adjusting one or more engine and / or combustion parameters so as to increase the concentration of CO in the engine-out emission; wherein the target CO concentration is determined on the basis of a correlation with indicators of combustion efficiency under known engine operating conditions. Exhaust gas recirculation (EGR) is one such engine and / or combustion parameter. A method for controlling an internal combustion engine to obtain an engine-out emission level of NOx within a predetermined concentration range is also described. The methods may be implemented by an engine control unit.

Description

FIELD OF THE INVENTION[0001]This invention relates to methods for controlling an internal combustion engine to control combustion stability and / or reduce engine-out nitrogen oxides (NOx) emissions. In particular, the invention relates to methods for using the measurement of carbon monoxide (CO) in the engine-out emissions to control combustion stability and / or indicate the level of NOx in the engine out emissions.BACKGROUND OF THE INVENTION[0002]Current emissions legislation in, for example, the US and Europe, set strict limits on the acceptable levels of polluting gases that are tolerated in the exhaust gas emissions of compression ignition engines; and engines using lean burn (oxygen rich) combustion, including diesel and gasoline direct injection engines. However, future legislation is set to pose a far more serious challenge to the manufacturers of such engines.[0003]To overcome the challenge of reducing exhaust gas emissions, intense research and development is necessary in the...

AI Technical Summary

Benefits of technology

[0039]Accordingly, in a third aspect of the invention there is provided a method for controlling an internal combustion engine to obtain an engine-out emission level of NOx within a predetermined concentration range, the method comprising: measuring the concentration of CO in an engine-out emission; calculating the concentration of NOx in said engine-out emission based on a correlation with the measured concentration of CO; determining whether the calculated concentration of NOx for the engine under the operating conditions in use is above a predetermined concentration level; and where the calculated concentration of NOx is above the predetermined concentration level, operating one or more after-treatments to reduce the concentration of NOx in said engine-out emission to a level no greater than said predetermined concentration level.

[0043]Accordingly, a fourth aspect of the invention provides a method for controlling an internal combustion engine to obtain an engine-out emission level of NOx within a predetermined concentration range, the method comprising: measuring the concentration of CO in an engine-out emission; calculating the concentration of NOx in said engine-out emission based on a correlation with the measured concentration of CO; determining whether the calculated concentration of NOx for the engine under the operating conditions in use is within the predetermined concentration range; and where the calculated concentration of NOx is outside of the predetermined concentration range, adjusting one or more engine and / or combustion parameters so as to achieve an engine-out emission level of NOx within the predetermined concentration range; and operating one or more after-treatments to reduce the concentration of NOx in said engine-out emission.

Problems solved by technology

Typically, the known engine operating conditions include engine speed and load, which can affect combustion parameters and hence, engine-out emissions.

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