Method and apparatus for determining accumulation in a particulate filter of an emission abatement assembly

1 . A method of operating an emission abatement assembly to remove soot from the exhaust gas of an internal combustion engine, the method comprising the steps of:

determining a pressure drop across a particulate filter,

determining an exhaust mass flow from the engine,

retrieving a limit value from a data table based on the exhaust mass flow, and

regenerating the particulate filter if the pressure drop across the filter exceeds the limit value.

2 . The method of claim 1 , wherein the retrieving step comprises querying the data table to determine the limit value from a plurality of limit values.

3 . The method of claim 2 , wherein each of the plurality of limit values corresponds to an exhaust mass flow value.

4 . The method of claim 1 , wherein the regenerating step comprises operating a fuel-fired burner to generate heat to regenerate the particulate filter.

5 . The method of claim 1 , wherein the step of determining the exhaust mass flow comprises monitoring output from a mass flow sensor.

6 . The method of claim 1 , wherein the step of determining the exhaust mass flow comprises estimating the exhaust mass flow from sensed engine operation parameters.

7 . The method of claim 1 , wherein the step of determining the pressure drop across the particulate filter comprises monitoring the output from at least one pressure sensor positioned to sense the pressure drop across the particulate filter.

8 . An emission abatement assembly for removing soot from the exhaust gas of an internal combustion engine, the assembly comprising:

a particulate filter,

a fuel-fired burner positioned upstream of the particulate filter, and

a controller configured to control the fuel-fired burner, the controller comprising (i) a processor, and (ii) a memory device electrically coupled to the processor, the memory device having stored therein a plurality of instructions which, when executed by the processor, cause the processor to:

determine a pressure drop across the particulate filter,

determine an exhaust mass flow from the engine,

retrieve a limit value from a data table based on the exhaust mass flow, and

operate the fuel-fired burner to regenerate the particulate filter if the pressure drop across the filter exceeds the limit value.

9 . The emission abatement assembly of claim 8 , wherein the plurality of instructions, when executed by the processor, further cause the processor to query the data table to determine the limit value from a plurality of limit values.

10 . The emission abatement assembly of claim 9 , wherein each of the plurality of limit values corresponds to an exhaust mass flow value.

11 . The emission abatement assembly of claim 8 , further comprising a mass flow sensor, wherein the plurality of instructions, when executed by the processor, further cause the processor to monitor output from the mass flow sensor.

12 . The emission abatement assembly of claim 8 , wherein the plurality of instructions, when executed by the processor, further cause the processor to estimate the exhaust mass flow from sensed engine operation parameters.

13 . The emission abatement assembly of claim 8 , further comprising at least one pressure sensor positioned to sense a pressure drop across the particulate filter, wherein the plurality of instructions, when executed by the processor, further cause the processor to monitor output from the at least one pressure sensor to determine the pressure drop across the particulate filter.

14 . A method of operating an emission abatement assembly to remove soot from the exhaust gas of an internal combustion engine, the method comprising the steps of:

determining a pressure drop across a particulate filter,

determining a limit value based on an exhaust mass flow from the engine, and

regenerating the particulate filter if the pressure drop across the filter exceeds the limit value.

15 . The method of claim 14 , wherein the step of determining the limit value comprises querying a data table to determine the limit value from a plurality of limit values based on the exhaust mass flow from the engine.

16 . The method of claim 15 , wherein each of the plurality of limit values corresponds to an exhaust mass flow value.

17 . The method of claim 14 , wherein the regenerating step comprises operating a fuel-fired burner to generate heat to regenerate the particulate filter.

18 . The method of claim 14 , further comprising the step of determining the exhaust mass flow from the output of a mass flow sensor.

19 . The method of claim 14 , further comprising the step of estimating the exhaust mass flow from sensed engine operation parameters.

20 . The method of claim 14 , wherein the step of determining the pressure drop across the particulate filter comprises monitoring the output from at least one pressure sensor positioned to sense the pressure drop across the particulate filter.