Particulate matter sensing device for controlling and diagnosing diesel particulate filter systems

An exhaust gas processing system of an internal combustion engine, comprising:

• a diesel particulate filter;
• a heating device positioned upstream from said diesel particulate filter for regenerating said diesel particulate filter;
• a PM sensor including a first particulate filter piece positioned in between a first electrode and a second electrode receiving an incoming exhaust gas flow, a second particulate filter piece positioned in between a third electrode and said second electrode receiving an exhaust gas flow which passes through said first particulate filter piece, an impedance measurement circuit electrically connected to said first electrode, said second electrode and said third electrode, generating a first impedance sensing signal indicative of an impedance in between said first electrode and said second electrode and a second impedance sensing signal indicative of an impedance in between said third electrode and said second electrode, and a sensor controller adapted to provide a PM sensing signal indicative of a particulate matters amount in said incoming exhaust gas flow in response to said first impedance sensing signal and said second impedance sensing signal;
• and
• a filter regeneration controller for regenerating said diesel particulate filter by operating said heating device in response to at least said PM sensing signal generated from said PM sensor.

A diagnostic control apparatus for detecting PM emission issues in an exhaust gas processing system of an internal combustion engine, comprising:

• a diesel particulate filter;
• a first PM sensor positioned downstream from said diesel particulate filter including a first particulate filter piece positioned in between a first electrode and a second electrode receiving an incoming exhaust gas flow, a second particulate filter piece positioned in between a third electrode and said second electrode receiving an exhaust gas flow which passes through said first particulate filter piece, an impedance measurement circuit electrically connected to said first electrode, said second electrode and said third electrode, generating a first impedance sensing signal indicative of an impedance in between said first electrode and said second electrode and a second impedance sensing signal indicative of an impedance in between said third electrode and said second electrode, and a sensor controller adapted to provide a first PM sensing signal indicative of a particulate matters amount in said incoming exhaust gas flow in response to said first impedance sensing signal and said second impedance sensing signal, and adapted to start a sensor regeneration process, in which said second electrode in said PM sensor is resistively heated for deposited PM, in response to said PM sensing signal;
• and
• a diagnostic controller configured to determine and indicate a PM emission issue in said exhaust gas processing system in response to at least said first PM sensing signal generated in said first PM sensor.