The Effect of Mounting Orientation of Resistive Particulate Matter Sensor on Signal Behavior

Particulate Matter (PM) sensors are required to monitor the diesel particulate filters (DPF) malfunction. The resistive PM sensor concept is widely chosen for this purpose due to its functionality, costs and durability. The output signal of resistive PM sensor for interpreting and processing for diagnosing DPF status is significantly affected by the exhaust velocity and soot concentration in the vicinity of sensor sensing element. Theoretically, during the regeneration of PM sensor, no new accumulation of particles is possible. Even after the regeneration, PM cannot immediately be accumulated again, because of thermal inertia, the PM sensor requires a certain time for the thermalization of the sensor element by the exhaust gas. During the regeneration phase and the subsequent cooling phase, PM sensor is insensitive with respect to a possibly present soot concentration, but the choking phenomena of PM sensor can be observed, when soot depositing rate reaches a threshold value.