Apparatus, system, and method for estimating particulate consumption

• US 20070056273A1
• Filed: 09/15/2005
• Published: 03/15/2007
• Est. Priority Date: 09/15/2005
• Status: Active Grant

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Wills, J.
• Granted Patent: US 7,562,524 B2
• Time in Patent Office: Days
• US Class Current: 60/297
• CPC Class Codes: F01N 11/002 the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• CPC Class Codes: F01N 3/0231 using special exhaust apparatus upstream of the filter for producing nitrogen dioxide, e.g. for continuous filter regeneration systems [CRT]
• CPC Class Codes: F01N 9/002 of filter regeneration, e.g. detection of clogging
• CPC Class Codes: F02B 37/00 Engines characterised by provision of pumps driven at least for part of the time by exhaust
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An apparatus, system, and method are disclosed for robustly estimating soot oxidation rates on a particulate filter. The invention uses empirically measured soot consumption rates as defined boundary rates, and operates between those rates using theoretical relationships between soot consumption and various operating conditions. The invention may also operate outside the defined boundaries by extrapolating the theoretical relationships beyond the defined boundary. The invention thereby overcomes the inflexibility of empirical modeling by allowing reasonable estimates at points that are not explicitly measured, and it overcomes the sensitivity of theoretical models to non-idealities that are experienced in real applications.

Claims

1. An apparatus for estimating particulate consumption in a particulate filter, the apparatus comprising:

an empirical boundary conditions module, the empirical boundary conditions module configured to store boundary soot consumption rates corresponding to defined operating conditions;

a defined relationships module, the defined relationships module configured to store relationship information between a plurality of potential operating conditions and the boundary soot consumption rates;

a condition index module, the condition index module configured to determine a condition index value according to current operating conditions and the stored relationship information; and

a final output value module, the final output value module configured to combine the condition index value with the boundary soot consumption rates to determine a final output value of current soot consumption rate.

2. The apparatus of claim 1, wherein the boundary soot consumption rates comprise soot consumption rates via oxidation.

3. The apparatus of claim 1, wherein the boundary soot consumption rates comprise soot consumption rates via noxidation.

4. The apparatus of claim 2, wherein the soot consumption rates via oxidation on the particulate filter comprise an oxidation high rate and an oxidation low rate, the defined operating conditions comprise particulate filter temperature, O₂ mass fraction, and soot loading on the particulate filter, the plurality of potential operating conditions comprise particulate filter temperature, O₂ mass fraction, and soot loading on the particulate filter, and the stored relationship information comprises a plurality of soot consumption ratios, the ratios comprising the soot consumption rate associated with each of the plurality of potential operating conditions divided by the difference between the oxidation high rate and the oxidation low rate.

5. The apparatus of claim 4, wherein the oxidation low rate equals zero.

6. The apparatus of claim 3, wherein the soot consumption rates via noxidation on the particulate filter comprise a noxidation high rate and a noxidation low rate, the defined operating conditions comprise particulate filter temperature, NO₂ mass flow rate, and soot loading on the particulate filter, the plurality of potential operating conditions comprise particulate filter temperature, NO₂ mass flow rate, and soot loading on the particulate filter, and the stored relationship information comprises a plurality of soot consumption ratios, the ratios comprising the soot consumption rate associated with each of the plurality of potential operating conditions divided by the difference between the noxidation high rate and the noxidation low rate.

7. The apparatus of claim 4, wherein the condition index value comprises a normalized value on a scale from a low value to a high value, the low value for the condition index value corresponds to the oxidation low rate, the high value for the condition index value corresponds to the oxidation high rate, and the final output value module is configured to linearly interpolate between the oxidation low rate and the oxidation high rate for a condition index value between the low value and the high value.

8. The apparatus of claim 7, wherein the final output value module is further configured to linearly extrapolate below the oxidation low rate for condition index values below the low value, and linearly extrapolate above the oxidation high rate for condition index values above the high value.

9. The apparatus of claim 6, wherein the condition index value comprises a normalized value on a scale from a low value to a high value, the low value for the condition index value corresponds to the noxidation low rate, the high value for the condition index value corresponds to the noxidation high rate, the final output value module is configured to linearly interpolate between the noxidation low rate and the noxidation high rate for condition index values between the low value and the high value, and wherein the final output value module is further configured to linearly extrapolate below the noxidation low rate for condition index values below the low value, and linearly extrapolate above the noxidation high rate for condition index values above the high value.

10. A signal bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations to estimate the rate of particulate consumption in a particulate filter, the operations comprising:

storing boundary soot consumption rates determined according to defined operating conditions;

storing relationship information between a plurality of potential operating conditions and the boundary soot consumption rates;

determining a condition index value determined according to current operating conditions and the stored relationship information; and

combining the condition index value with the boundary soot consumption rates to produce a final output value of soot consumption rate.

11. The signal bearing medium of claim 10, wherein the boundary soot consumption rates comprise soot consumption rates via oxidation, the soot consumption rates via oxidation comprise an oxidation high rate and an oxidation low rate, the defined operating conditions comprise particulate filter temperature, O₂ mass fraction, and soot loading on the particulate filter values, the plurality of potential operating conditions comprise a range of particulate filter temperature, O₂ mass fraction, and soot loading on the particulate filter, and wherein the stored relationship information comprises a plurality of soot consumption ratios, the ratios comprising the soot consumption rate associated with each of the plurality of potential operating conditions divided by the difference between the oxidation high rate and the oxidation low rate.

12. The signal bearing medium of claim 10, wherein the boundary soot consumption rates comprise soot consumption rates via noxidation, the soot consumption rates via noxidation comprise a noxidation high rate and a noxidation low rate, the defined operating conditions comprise particulate filter temperature, NO₂ mass flow rate, and soot loading on the particulate filter, the plurality of potential operating conditions comprise particulate filter temperature, NO₂ mass flow rate, and soot loading on particulate filter, and wherein the stored relationship information comprises a plurality of soot consumption ratios, the ratios comprising the soot consumption rate associated with each of the plurality of potential operating conditions divided by the difference between the noxidation high rate and the noxidation low rate.

13. The signal bearing medium of claim 11, wherein the condition index value comprises a normalized value on a scale from a low value to a high value, the low value for the condition index value corresponds to the oxidation low rate, the high value for the condition index value corresponds to the oxidation high rate, and wherein combining the condition index value with the boundary soot consumption rates comprises linearly interpolating between the oxidation low rate and the oxidation high rate for condition index values between the low value and the high value, and linearly extrapolating below the oxidation low rate for condition index values below the low value, and linearly extrapolating above the oxidation high rate for condition index values above the high value.

14. The signal bearing medium of claim 12, wherein the condition index value comprises a normalized value on a scale from a low value to a high value, the low value for the condition index value corresponds to the noxidation low rate, the high value for the condition index value corresponds to the noxidation high rate, and wherein combining the condition index values with the boundary soot consumption rates comprises linearly interpolating between the noxidation low rate and the noxidation high rate for condition index values between the low value and the high value, and linearly extrapolating below the noxidation low rate for condition index values below the low value, and linearly extrapolating above the noxidation high rate for condition index values above the high value.

15. A method for estimating particulate consumption in a particulate filter, the method comprising:

storing boundary soot consumption rates determined according to defined operating conditions;

storing relationship information between a plurality of potential operating conditions and the boundary soot consumption rates;

determining a condition index value determined according to current operating conditions and the stored relationship information; and

combining the condition index value with the boundary soot consumption rates to produce a final output value of soot consumption rate.

16. The method of claim 15, wherein the boundary soot consumption rates comprise soot consumption rates via oxidation, the soot consumption rates via oxidation comprise an oxidation high rate and an oxidation low rate, and the defined operating conditions comprise particulate filter temperature, O₂ mass fraction, and soot loading on the particulate filter.

17. The method of claim 15, wherein the boundary soot consumption rates comprise soot consumption rates via noxidation, the soot consumption rates via noxidation comprise a noxidation high rate and a noxidation low rate, and the defined operating conditions comprise particulate filter temperature, NO₂ mass flow rate, and soot loading on the particulate filter.

18. The method of claim 16, wherein the condition index value comprises a normalized value on a scale from a low value to a high value, the low value for the condition index value corresponds to the oxidation low rate, the high value for the condition index value corresponds to the oxidation high rate, wherein combining the condition index value with the boundary soot consumption rates comprises linearly interpolating between the oxidation low rate and the oxidation high rate for condition index values between the low value and the high value, and linearly extrapolating below the oxidation low rate for condition index values below the low value, and linearly extrapolating above the oxidation high rate for condition index values above the high value.

19. The method of claim 17, wherein the condition index value comprises a normalized value on a scale from a low value to a high value, the low value for the condition index value corresponds to the noxidation low rate, the high value for the condition index value corresponds to the noxidation high rate, wherein combining the condition index value with the boundary soot consumption rates comprises linearly interpolating between the noxidation low rate and the noxidation high rate for condition index values between the low value and the high value, and linearly extrapolating below the noxidation low rate for condition index values below the low value, and linearly extrapolating above the noxidation high rate for condition index values above the high value.

20. An exhaust gas after-treatment system for determining the rate of soot consumption on a particulate filter, the system comprising:

a particulate filter configured to capture particulate matter from an exhaust gas stream;

a temperature sensor configured to estimate the particulate filter temperature;

a flow rate sensor configured to estimate the mass flow rate of exhaust through the particulate filter;

an O₂ estimator configured to estimate the mass fraction of O₂ through the particulate filter;

a soot load estimator configured to estimate the soot loading on the particulate filter; and

a controller configured to store a high rate of soot oxidation and a low rate of soot oxidation based on defined operating conditions, to store relationships between a plurality of potential operating conditions and the high and low soot oxidation rates, to determine a conditions index determined according to current operating conditions, and to combine the conditions index with the high rate of soot oxidation and low rate of soot oxidation to determine a rate of soot consumption on the particulate filter.

21. The system of claim 20, further comprising an internal combustion engine that produces exhaust gas as a byproduct of operation, wherein the internal combustion engine is fluidly coupled to the particulate filter, wherein the operating conditions of the exhaust gas aftertreatement system are influenced by the current operating conditions of the engine, and wherein the defined operating conditions of the exhaust gas aftertreatement system are influenced by the combustion related hardware characteristics of the engine.