Method for determining load on particulate filter for engine exhaust, including estimation of ash content

Abstract

A method for determining the load on an internal combustion engine exhaust particulate filter optimizes filter regeneration by determining the portion of the filter load constituted by accumulated ash. In one technique, the ash load is determined by recording the lowest value of DPF load over a time or distance interval. In another technique, an estimate is made of the amount of load remaining at each of a plurality of DPF regeneration events; the amount of remaining load immediately following the regeneration event corresponds to the amount of accumulated ash in the DPF. DPF load estimation is performed using equations for laminar or turbulent flow in pipes. These equations establish a linear or quadratic relationship between the flow through the DPF and the pressure drop measured across it.