Trapped soot estimator

摘要

A diesel engine (10) has an exhaust system (16) containing a diesel particulate filter (18) for trapping soot passing through the exhaust system as the engine operates. A trapped soot estimator (30) estimates soot trapped in the diesel particular filter by repeatedly executing an algorithm that calculates a data value for total soot trapped using Kalman filter processing (48) whose gain is controlled by at least one engine operating parameter.

主权项

1. A diesel engine system comprising:
a diesel engine which emits soot during its operation; an exhaust system comprising a diesel particulate filter disposed downstream from the diesel engine for trapping soot passing through the exhaust system as the diesel engine operates; a processor-based control system for estimating soot trapped in the diesel particulate filter as the diesel engine operates, wherein the processor-based control system is configured: a) to process data values for a current engine speed and a current engine torque for selecting from a steady-state soot estimation table containing data values of steady-state soot correlated with data values for the engine speed and the engine torque, a current data value for steady-state soot entering the diesel particulate filter, and for selecting from a transient soot estimation table containing data values of transient soot correlated with data values for the engine speed and the engine torque, a current data value for transient soot entering the diesel particulate filter; b) to calculate a current data value for a feed-forward instantaneous soot estimate by weighting the current data value for steady-state soot and the current data value for transient soot as a function of changing engine operation, summing the weighted data values and subtracting a current data value for trapped soot being burned off by natural regeneration; c) to repeatedly update a data value for a total soot estimate of soot trapped in the diesel particulate filter by adding to an existing data value for the total soot estimate the result of integrating a current data value for feed-forward instantaneous soot over a length of time since a prior or update while also correcting the data value for the total soot estimate by calculating a current data value for soot error between a current total soot estimate and a data value for trapped soot based on a current exhaust flow rate and a current differential pressure across the diesel particulate filter and processing the current data value for soot error by a Kalman filter processing gain; wherein the Kalman filter processing gain is controlled by at least one parameter related to engine operation; and d) to initiate regeneration of the diesel particulate filter when the data value for the total soot estimate reaches a predetermined value, thereby increasing a temperature of the diesel particulate filter to burn off soot trapped in the diesel particulate filter to reduce the impedance of the exhaust flow through the diesel particulate filter.