Regeneration Control System For Exhaust Filter And Method

Abstract

A regeneration control system for an exhaust filter in an internal combustion engine system includes a first sensing mechanism for monitoring an exhaust flow resistance of the exhaust filter, and a second sensing mechanism for monitoring an attenuation of electromagnetic energy transmitted through the exhaust filter. The regeneration control system further includes an electronic controller coupled with the sensing mechanisms and configured to output a filter regeneration command responsive to an amount of particulate matter trapped within the exhaust filter. The electronic controller is further configured to weight data from the first and second sensing mechanisms in determining the amount of particulate matter. Weighting of the data may be responsive to an operating state of the internal combustion engine system. Related methodology is also disclosed.

What is claimed is: 
     
         1 . A method of operating an internal combustion engine system comprising the steps of:
 operating the internal combustion engine system in a first operating state at an earlier time, and in a second operating state at a later time;   trapping particulate matter in exhaust produced by the internal combustion engine in each of the first and second operating states within an exhaust filter;   receiving data from a first sensing mechanism monitoring exhaust flow resistance through the exhaust filter, and from a second sensing mechanism monitoring attenuation of electromagnetic energy transmitted through the exhaust filter, in each of the first and second operating states;   commanding a first regeneration of the exhaust filter in the first operating state at a time determined using a first relative weighting of the data from the first and second sensing mechanisms; and   commanding a second regeneration of the exhaust filter in the second operating state at a time determined using a second relative weighting of the data from the first and second sensing mechanisms that is different from the first relative weighting.   
     
     
         2 . The method of  claim 1  wherein the first operating state includes a lower soot loading state of the exhaust filter, and the second operating state includes a higher soot loading state of the exhaust filter. 
     
     
         3 . The method of  claim 2  further comprising the steps of:
 determining the time of the first regeneration responsive to satisfaction of a first regeneration suitability criterion in the lower soot loading state; and 
 determining the time of the second regeneration responsive to satisfaction of a second regeneration suitability criterion in the higher soot loading state. 
 
     
     
         4 . The method of  claim 3  wherein the first regeneration suitability criterion includes an engine speed parameter, an engine load parameter, a temperature parameter, or a machine travel parameter. 
     
     
         5 . A regeneration control system for an exhaust filter in an internal combustion engine system comprising:
 a first sensing mechanism configured to monitor an exhaust flow resistance of the exhaust filter;   a second sensing mechanism configured to monitor an attenuation of electromagnetic energy transmitted through the exhaust filter;   an electronic controller coupled with each of the first and second sensing mechanisms, the electronic controller being configured to output a filter regeneration command responsive to an amount of particulate matter trapped within the exhaust filter;   the electronic controller being further configured to receive a signal indicative of a change in an operating state of the internal combustion engine system from a first operating state to a second operating state; and   the electronic controller being further configured to weight data from the first and second sensing mechanisms to a first relative extent in determining the amount of particulate matter in the first operating state; and   the electronic controller being further configured to weight data from the first and second sensing mechanism to a second relative extent in determining the amount of particulate matter in the second operating state.   
     
     
         6 . The system of  claim 5  wherein the operating state of the internal combustion engine system includes a relative soot loading state of the exhaust filter. 
     
     
         7 . The system of  claim 6  wherein the electronic controller is further configured to weight the data such that data from the second sensing mechanism is used at least predominantly if the exhaust filter is in a lower soot loading state, and such that data from the first sensing mechanism is used at least predominantly if the exhaust filter is in a higher soot loading state. 
     
     
         8 . The system of  claim 7  wherein the electronic controller is configured to determine whether a first regeneration suitability condition is satisfied if the exhaust filter is in the lower soot loading state, and whether a second, different regeneration suitability condition is satisfied if the exhaust filter is in the higher soot loading state. 
     
     
         9 . The system of  claim 8  wherein the first regeneration suitability condition includes at least one criterion other than the amount of particulate matter trapped within the exhaust filter. 
     
     
         10 . The system of  claim 9  wherein the at least one criterion includes an engine speed parameter, an engine load parameter, a temperature parameter, or a machine travel parameter. 
     
     
         11 . The system of  claim 5  wherein:
 the first sensing mechanism includes a first sensor exposed to a pressure of exhaust within an exhaust conduit of the internal combustion engine system at a location upstream of the exhaust filter and a second sensor exposed to a pressure of exhaust within the exhaust conduit at a location downstream of the exhaust filter; and 
 the second sensing mechanism includes a transmitter configured to transmit electromagnetic energy through the exhaust filter, and a receiver configured to sense a strength of the transmitted electromagnetic energy after having been attenuated in response to trapped soot within the exhaust filter. 
 
     
     
         12 . An exhaust filter system for trapping particulates in an internal combustion engine system comprising:
 an exhaust filter including a housing having an inlet configured to connect with an exhaust conduit of an internal combustion engine, an outlet, and a filter medium positioned within the housing, the exhaust filter being configured to trap particulates in exhaust from the internal combustion engine; and   a regeneration control system including a first sensing mechanism for monitoring an exhaust flow resistance of the exhaust filter, a second sensing mechanism for monitoring an attenuation of electromagnetic energy transmitted through the exhaust filter, and an electronic controller coupled with the first and second sensing mechanisms;   the electronic controller being configured to determine a value indicative of an amount of particulate matter trapped within the exhaust filter and to output a filter regeneration command responsive to the determined value, and wherein the electronic controller is further configured to weight data from the first sensing mechanism and data from the second sensing mechanism to different relative extents in determining the value, responsive to an operating state of the internal combustion engine system.   
     
     
         13 . The system of  claim 12  wherein the electronic controller is further configured to weight the data such that data from the second sensing mechanism is used at least predominantly if the exhaust filter is in a lower soot loading state, and data from the first sensing mechanism is used at least predominantly if the exhaust filter is in a higher soot loading state. 
     
     
         14 . The system of  claim 13  wherein the first sensing mechanism includes a first pressure sensor exposed to a pressure of exhaust at a location upstream the inlet, and a second pressure sensor exposed to a pressure of exhaust at a location downstream the outlet. 
     
     
         15 . The system of  claim 14  further comprising the exhaust conduit, and a diesel oxidation catalyst positioned within the exhaust conduit at a location downstream the first pressure sensor and upstream the inlet. 
     
     
         16 . The system of  claim 13  wherein the second sensing mechanism includes a transmitter configured to transmit electromagnetic energy through the exhaust filter, and a receiver configured to sense a strength of the transmitted electromagnetic energy after having been attenuated in response to trapped soot. 
     
     
         17 . The system of  claim 16  wherein the transmitter is configured to transmit a band of electromagnetic frequencies less than about 2 GHz. 
     
     
         18 . The system of  claim 12  further comprising a third sensing mechanism coupled with the electronic controller, and wherein the electronic controller is further configured to determine regeneration suitability of the exhaust filter responsive to data from the third sensing mechanism. 
     
     
         19 . The system of  claim 18  wherein the third sensing mechanism includes at least one of an engine speed sensor and an engine load sensor.