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With a goal to meet 2010 heavy-duty emission standards with minimal engine-out NOx, Southwest Research Institute (SwRI) engineers applied sliding mode control methods to high-EGR (exhaust gas recirculation) diesel engines.
The airflow-dominant fueling of these engines — where fuel follows air — simultaneously resulted in combustion stability and managed pollutant production at the source. However, engineers also knew from the start that the torque response of these engines would suffer if the air supply was insufficient.
Because sluggish torque performance could result, particularly in the case of a turbocharged engine where the air supply and the fueling are inherently interdependent, the challenge was to find a natural, built-in cross-coupling between the air and the EGR actuators.
Engineers followed a systematic method to design a sliding mode controller to achieve a high-performance, low-emission diesel engine. Because another challenge existed — differences in engine models — one of the key features of the method used was that it took into account the differences in engine models, and as a result, no particular model of turbocharger was needed. Good torque response, along with reasonable NOx spike and low opacity, was achieved with the method.
The method was verified via constant-speed up and down torque transients. Pedal up-transients from an idle condition to maximum torque were achieved in approximately two seconds. NOx spikes were controlled to double the steady-state levels. No noticeable opacity spikes were observed. These results compared favorably to data obtained from engine under its stock control, which had NOx spikes of four times the steady-state levels and opacity spikes of 35 percent or greater.
For more information about our powertrain control capabilities, or how you can contract with SwRI, please contact Jayant Sarlashkar at jsarlashkar@swri.org or (210) 522-5506.
powertraincontroltech.swri.org
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| Engine and Vehicle R&D Department | Engine, Emissions & Vehicle Research Division | SwRI Home | |
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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions. |
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December 28, 2012 |
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