With the start of Euro 6d regulations, gasoline particulate filters (GPF) have become standard equipment in European vehicles with gasoline-direct-injection engines. GPFs will also be broadly applied to meet the upcoming China 6 regulations. An existing challenge with GPFs is accurate soot load detection to manage the pressure loss across the exhaust system and to protect the GPFs from soot overload, which could potentially cause damage as result of uncontrolled soot oxidations. Systems with the GPF located in the under-floor position have a higher potential risk of soot overload due to lower temperatures, which can result in higher soot accumulation rates.
The accuracy of existing soot estimation methods such as evaluation of the pressure drop of the soot-loaded GPF or model-based balancing of soot accumulation versus soot oxidation rates are sensitive to transient operating condition of a vehicle. Identifying an alternative method for accurate monitoring of the soot-loading state of a GPF is highly beneficial and could help to improve protection and soot management strategies for GPFs significantly.
In this contribution, we will evaluate the application of RF-Sensors for on-board soot monitoring of GPFs operated on test vehicles. We will discuss the sensitivity of the RF-Signal to different soot types, non-uniformity in soot distribution, as well as the impact of different operating conditions like the transient GPF temperature.