CONTROL AND PROCESS SUPERVISION OF A PARTICLE FILTER SYSTEM FOR DIESEL-ENGINES

In particle filter systems for diesel engines in urban traffic, the re generation of the filter by burning off the soot is a problem. Changes in the engine operating mode during the regeneration make a controlle d combustion of the soot in the filter difficult. This paper presents a control concept with process supervision for a filter system with bu rner-assisted full-flow regeneration during engine operation. The goal of the control is to keep the mixed gas temperature in front of the f ilter at the desired value by manipulating the amount of fuel injected into the burner. The process supervision must ensure that the flame i n the burner does not go out, as otherwise unburned fuel will combust in the filter and/or emit as blue smoke; this has to be avoided. The c ontroller and the process supervision are designed based on linear and nonlinear system identification. Measurements of the controller perfo rmance made on a test engine show a good behaviour of the closed loop, even during large and rapid variations of engine load.