The Development and Testing of an Active Particulate Regeneration System Using Model Based Control

With ever tightening vehicle emissions standards the fitment of Diesel Particulate Filter (DPF) systems will become common in the US, Europe and Japan. While in most circumstances filters may be regenerated passively there is a risk that this will not always be possible due to the low exhaust gas temperatures in certain stop-start duty cycles (such as urban buses, garbage trucks, etc.). In order to operate in such cycles active regeneration will be required.

A potential active regeneration method is to inject diesel fuel upstream of a catalyst and use the resulting exotherm from the combustion of the fuel to regenerate the particulate trap. In order for this to occur, the catalyst must be above the light off temperature, so it is necessary to understand the condition of the catalyst prior to initiating regeneration. Using diesel fuel for regeneration obviously has an impact on the fuel consumption of the vehicle so it is important to understand the soot loading of a particulate trap during operation to maximize the time between active regenerations.

This paper describes the development and testing of an active regeneration system including a catalyst, a particulate trap and a model based control system. The control system will model the soot loading and passive regeneration of the filter to allow the maximum time between active regeneration events, thus minimizing fuel penalty. The system also models the condition of the catalyst and uses this for both active and passive regeneration calculations for the particulate trap subroutine of the control algorithm.