Diesel Filters OBD Using a Simple Concept

On Board Diagnostic of Diesel Particulate Filters remain an important technical challenge due to the very low soot concentrations after a leaking filter. These concentration levels in the range of 5 to 20 mg/m3 are difficult to measure without relatively complex lab equipment. Various methods are being investigated to fulfill the OBD requirement in Europe and in the US including soot sensors. However they often require a complex signal processing and expensive electronics to be able to measure accurately and repeatedly the low soot concentration levels. The method described in this paper consists of a simple concept using a small detection filter located downstream the main Diesel Particulate Filter and a temperature sensor positioned at the detection filter outlet. Steady state engine bench and vehicle driven on the road and on a chassis dynamometer testing are used to demonstrate the correlation between the soot emissions after the main Diesel filter and the temperature measurements. After introducing the concept and the soot emissions measurement principle, we will show the steady state engine bench testing results, demonstrating the ability to clearly discriminate soot emissions as low as 0 mg/m3, 10 mg/m3 and 20 mg/m3. The same concept is installed on vehicle equipped with a 1.7L Diesel engine and driven on a chassis dynamometer following the Standardized European Cycle (NEUDC). Calibrated Diesel Particulate Filter Leakages of 0.006 g/km (0.004 g/mi) and 0.011 g/km (0.007 g/mi) are distinctly detected. This simple approach using existing and proven hardware such as a diesel filter and a temperature sensor is a cost effective solution to achieve the OBD requirement. No sophisticated electronics is required what makes it very robust and durable for light and heavy duty or any other Diesel application.

Presenter
Said Zidat, Katcon