F2008-05-073
Particle Sensor Technology for Engine Control and On Board Diagnostics
Dipl.-Phys. Univ. Manfred Weigl Sept. 4th 2007 Siemens VDO Automotive AG, Regensburg
Particle Sensor Technology for Engine Control and On-Board Diagnostics Abstract: The first step in the development of particle sensors for automotive application is, to find an appropriate definition of the measurand. The definitions for particle mass and particle count will be application specific and correlated to the measuring principles, because they are no well defined physical properties. Three different sensor applications will be highlighted: o With the implementation of electronic diesel engine management, the first particle sen-sor application was intended for the engine out emissions, to provide a feedback for engine control. The trade off between particle- and NOx-concentration could have been controlled in a closed loop. o Since legislation substantiated the OBD requirements concerning particle filter systems, a sensor downstream of the particle filter is requested for a reliable detection of system malfunctions. o Since the implementation of particle filters in diesel vehicles, methods for measuring the particle load, especially the mass of the stored carbon were requested. Sensor sys-tems for direct soot load measurement could make an essential contribution to the reli-ability of the filter systems. The sensor systems can be divided in two groups, the fast sensors and sensors which detect the agglomeration of particles on a sensor surface. In the first group are the electrostatic systems, which measure the flow of electric charge, caused by particles. These sensor systems could provide a real time signal as feedback for engine control as well as for on-board diagnostics. The second group of sensors will be usable only for failure detection in particle filter systems, because of the poor time resolution. A sensor downstream of the particle filter will not be able to provide information for use in engine control, because the filter will attenuate each impact of engine control parameters on soot below the limit of detection. A basically different sensor system is intended for measuring the soot load in particle filters. The task is a reliable measurement of the stored carbon mass to optimize regeneration cycles and to notify if ash cleaning is required. Problems and approaches concerning the above mentioned groups of sensors will be pre-sented.
This abstract is supplemented by a PDF, which can be viewed here.
Session: Sensor Systems