The RF-DPFTM diesel particulate filter sensor provides a direct, real-time measurement of filter soot and ash levels by utilizing the filter housing as an RF resonant cavity. Monitoring the response of specific cavity resonant modes allows for the measurement of the following filter-related parameters:
1. Direct measurement of filter soot levels
2. Direct measurement of filter ash levels
3. Determination of the material spatial distribution
Real-time measurement of the DPF loading state using the RF-DPFTM sensor enables feedback control and optimization of the filter regeneration process and management of the aftertreatment system. Improved sensing and control of these processes provide cost savings and accelerates development times for OEM customers, while delivering additional fuel savings and extended component life to end users.
Results of fleet testing on a heavy-duty truck platform has shown the potential to decrease regeneration duration and extend the time between regenerations. The tests used the stock OEM controls but monitored DPF loading levels directly using the RF-DPFTM. Figure 1 shows two repeated regeneration events (A) and (B). RF measurements indicate nearly complete soot oxidation during the first few minutes of the first regeneration (A), although the process continues much longer, with a second regeneration (B) initiated with an nearly clean filter. Figure 2 provides additional results showing three regeneration events, each at relatively low filter soot levels.
Engine dynamometer testing and sensor benchmarking have shown good agreement with gravimetrically-determined DPF soot levels. Transient response over simulated drive cycles is also quite comparable to conventional laboratory particulate matter measurement instrumentation. Results of testing conducted at Oak Ridge National Laboratory to benchmark the RF-DPFTMsensor response with the AVL Micro-Soot sensor is shown in Figure 3. The results show good correlation between the instantaneous change in DPF soot load computed from the RF signal and the measured engine-out soot emissions from the AVL system.