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	Exhaust aftertreatment components have become essential parts of new engine emission control technologies.
	Graph showing regeneration temperature control during speed-load transient operation. The DOC outlet temperature overshoot/ undershoot rate was effectively controlled to about 10 percent under challenging transient speed-load operations.

Diesel emission standards are becoming ever increasingly stringent. It is impossible to meet the emissions legislations by merely relying on the diesel engine technology itself. Exhaust aftertreatment components have become essential parts of new engine emission control technologies. Diesel particulate filters (DPFs) are the most effective control technology for particulate matter (PM) reduction.

Engineers at Southwest Research Institute (SwRI) initiated this program to find a way to control active DPF regeneration temperature at a desired level during engine transient conditions.

Approach

Filters physically capture diesel particulates to prevent their release to the atmosphere. However, soot accumulated inside the filters will increase engine backpressure and result in engine performance deterioration. Therefore, when soot accumulation reaches a certain level, removal of soot becomes necessary to maintain proper engine performance.

The process of removing soot from the DPF is defined as “regeneration.” In order to achieve reliable and robust filter regeneration, the aftertreatment system must have active regeneration capability, which requires sophisticated control strategies. Controlling the diesel oxidation catalyst (DOC)  outlet temperature/DPF inlet temperature at a desired value during engine transient conditions is one of the most challenging tasks in the overall control strategies.

Five representative engine test modes were selected to cover the operating scope of the engine and broad exhaust mass flow change range. Under the five respective modes, the dynamics of the temperature control system were thoroughly analyzed and characterized.

Outcome

The First Order Time Delay (FOTD) model was found effective to represent the dynamics of the temperature control system. Nonlinear compensation and gain scheduling techniques enhanced the transient response performance. A transient control scheme was implemented and tested under speed-load transient cycles at the engine test cell. The DOC outlet temperature overshoot/undershoot rate was effectively controlled to about 10% under challenging transient speed-load operations as shown in the lower figure above.

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

| Engine and Vehicle R&D Department | Engine, Emissions & Vehicle Research Division | SwRI Home |

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.

December 28, 2012