Concept for Diesel Particulate Filter monitoring based on BOSCH Particulate Matter Sensor (PMS)

Abstract

The use of Diesel Particulate Filters (DPF) for vehicle emission reduction is currently state of the art. In the early stages of development, the DPF systems were designed to be located under the vehicle body. The next step of development was a challenge for the packaging as the DPF was to be located near to the turbocharger (e.g. as a closed coupled system with Diesel Oxygen Catalyst DOC). The advantage of these kind of systems is the improved thermal behavior to reach the necessary temperatures for DPF regeneration compared to underbody systems.

Today the development of DPF systems is influenced by adding an additional feature: The converting of nitrogen oxide (NOx). For this requirement, dosing of the reductant liquid (AdBlue®) upstream of the DPF and a special coating on the surface of the DPF is necessary. The result is the strong reduction of particulate emissions AND nitrogen oxide (NOx) at the same time.

The requirements for certification of an engine or vehicle with those systems are constantly increasing. One of the criteria needed to fulfil the legal requirements is the On Board Diagnostics (OBD). The OBD-System has to detect a defective DPF if the emissions with this defect are above a limit value. These limits are constantly decreasing and this leads to a new focus of development to achieve a conforming monitoring concept for the detection of a defective DPF. One solution is the use of the PMSensor, which will be described in this article.

The functional principle of the PM-Sensor will be described at the beginning with special focus on the PM-Sensor component. Based on these fundamentals, the monitoring concept for the filtering performance of the DPF will be shown.