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	Filtered ion signal under standard diesel combustion mode
	Characteristics of ion signal under HCCI combustion at 1250 rpm

Homogeneous charge compression ignition (HCCI) combustion offers the benefit of simultaneous reduction of oxides of nitrogen (NO_x) and particulate matter (PM), both of which are regulated by the US Environmental Protection Agency (EPA). However, HCCI combustion can become destructive if it is not properly controlled.

One of the metrics usually controlled is the so-called "start of combustion." Start of combustion can be determined from in-cylinder pressure measurement. However, a measurement is expensive. Southwest Research Institute (SwRI) investigated uses of ion-current to determine start of combustion of an HCCI engine because ion-current measurement can be significantly cheaper than that of in-cylinder pressure.

Approach

• In-cylinder ion probes (modified glow plug)

• Correlation of ion signal and combustion process (cylinder pressure)

Challenges

• Weak ion signal at light load

• High combustion noise at high load

Tools Used

• RPECS™ with high-speed DAQ

• High voltage dc/dc converter (200-3000 V) to provide bias to ion probe

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