Preventing Soot Underestimation in Diesel Particulate Filters by Determining the Restriction Sensitivity of Soot

• US 20100313629A1
• Filed: 06/10/2009
• Published: 12/16/2010
• Est. Priority Date: 06/10/2009
• Status: Active Grant

• Current Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Original Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Inventors: Singh, Nishant
• Granted Patent: US 8,266,890 B2
• Time in Patent Office: Days
• US Class Current: 73/23.31
• 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 2900/1606 Particle filter loading or soot amount
• CPC Class Codes: F01N 3/023 using means for regenerating the filters, e.g. by burning trapped particles by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235
• CPC Class Codes: F02D 2200/0812 Particle filter loading
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method of determining a need to perform regeneration of a diesel particulate filter in a diesel engine exhaust predicts a soot load of a diesel particulate filter with a pressure change based soot load estimate based upon a pressure change across the diesel particulate filter at a first time and a second time. A restriction sensitivity for the diesel particulate filter is calculated based upon the pressure change across the diesel particulate filter at the first time and the second time. The method transitions from the pressure change based soot load estimate to a model based soot accumulation estimate of the soot load of the diesel particulate filter upon the restriction sensitivity falling below a predetermined threshold. Regeneration of the diesel particulate filter is requested after the estimated soot level reaches a preset level based upon the soot accumulation model.

Claims

1. A method of estimating a soot level within an exhaust gas particulate filter having an input and an output comprising:

generating a pressure change based soot load estimate within the exhaust gas particulate filter at a first time based upon a pressure change from an input to an output of an exhaust gas particulate filter;

generating a pressure change based soot load estimate within the exhaust gas particulate filter at the second time based upon the pressure change from the input to the output of the exhaust gas particulate filter;

calculating a restriction sensitivity of the exhaust gas particulate filter utilizing a restriction amount within the exhaust gas particulate filter at the first time and the second time and the soot load estimates within the exhaust gas particulate filter at the first time and the second time; and

selecting a model based soot load estimate for the exhaust gas particulate filter when the restriction sensitivity falls below a predetermined threshold.

2. The method of claim 1 further comprising:

measuring a pressure change between an input to an output of an exhaust gas particulate filter at a first time;

identifying a volumetric flow rate of exhaust gas at the first time;

determining the restriction amount within the exhaust gas particulate filter at the first time utilizing the measured pressure change within the exhaust gas particulate filter and the identified volumetric flow rate of the exhaust gas;

measuring a pressure change from the input to the output of the exhaust gas particulate filter at a second time;

identifying a second volumetric flow rate of exhaust gas at the second time; and

determining the restriction amount within the exhaust gas particulate filter at the second time utilizing the pressure change within the exhaust gas particulate filter and the identified second volumetric flow rate of the exhaust gas.

3. The method of claim 1 further comprising:

detecting a temperature of the exhaust gas particulate filter before determining the restriction amount within the exhaust gas particulate filter at the first time; and

restarting the method of estimating the soot level within the exhaust gas particulate filter if the temperature is outside of a predetermined range of temperatures.

4. The method of claim 1 further comprising:

detecting a temperature of the exhaust gas particulate filter before determining the restriction amount within the exhaust gas particulate filter at the second time; and

allowing T₂+T_n time to pass if the temperature at the second time is outside of a predetermined range of temperatures, wherein T₂ is the second time and T_n is additional time.

5. The method of claim 1 further comprising:

continuing the use of a pressure change based soot load estimate when the restriction sensitivity remains above a predetermined threshold.

6. The method of claim 1 further comprising:

comparing the volumetric flow rate of exhaust gas at the first time to a low flow rate limit and a high flow rate limit; and

restarting the method of estimating the soot level within the exhaust gas particulate filter if the volumetric flow rate value is not between the low flow rate limit or the high flow rate limit.

7. The method of claim 1, wherein the restriction sensitivity is determined using the following formula:

8. The method of claim 1, wherein the restriction within the exhaust gas particulate filter is determined using the following formula:

9. A method of determining a need to perform regeneration of a diesel particulate filter in a diesel engine exhaust comprising:

predicting a soot load of a diesel particulate filter with a pressure change based soot load estimate based upon a pressure change across the diesel particulate filter at a first time and a second time;

calculating a restriction sensitivity for the diesel particulate filter based upon the pressure change across the diesel particulate filter at the first time and the second time; and

transitioning from the pressure change based soot load estimate to estimating the soot load of the diesel particulate filter with a model based soot accumulation estimate upon the restriction sensitivity falling below a predetermined threshold.

10. The method of claim 9 further comprising:

requesting regeneration of the diesel particulate filter after the estimated soot level reaches a preset level based upon the soot accumulation model.

11. The method of claim 9, wherein the restriction sensitivity is determined using the following formula:

12. The method of claim 9, wherein the restriction within the exhaust gas particulate filter is determined using the following formula:

13. The method of claim 9, wherein predicting the soot load, calculating the restriction sensitivity, transitioning to the model based soot accumulation estimate, and requesting regeneration occur within a electronic control module of the diesel engine.

14. A method of selecting a soot estimation model for a diesel particulate filter comprising:

monitoring a volumetric flow rate of engine exhaust;

obtaining temperature information of the diesel particulate filter;

measuring a pressure change from an input to an output of the diesel particulate filter at a first time;

generating a pressure change based soot load estimate within the diesel particulate filter at the first time based upon the pressure change from the input to the output of an exhaust gas particulate filter;

comparing the pressure change based soot load estimate at the first time to a predetermined threshold;

selecting a model based soot load estimate for the diesel particulate filter when the pressure change based soot load estimate at the first time is above a predetermined threshold;

measuring a pressure change from an input to an output of the diesel particulate filter at a second time;

generating a pressure change based soot load estimate within the diesel particulate filter at the second time based upon the pressure change from the input to the output of an exhaust gas particulate filter;

calculating a restriction sensitivity for the diesel particulate filter utilizing the pressure change across the diesel particulate filter at the first time and a second time and the pressure change based soot load estimates within the diesel particulate filter at the first time and the second time;

selecting a model based soot load estimate for the diesel particulate filter when the restriction sensitivity is below a preset threshold.

15. The method of claim 14, wherein the restriction sensitivity is determined using the following formula:

16. The method of claim 14, wherein the restriction within the exhaust gas particulate filter is determined using the following formula:

17. The method of claim 14 further comprising:

continuing the use of a pressure change based soot load estimate when the restriction sensitivity remains above the predetermined threshold.

18. The method of claim 14 further comprising:

selecting a model based soot load estimate for the diesel particulate filter when the temperature information of the diesel particulate filter is not within an preset operating range.

19. The method of claim 14 further comprising:

selecting a model based soot load estimate for the diesel particulate filter when the volumetric flow rate of the exhaust is not within an preset operating range.

20. An exhaust gas particulate filter comprising:

an input;

an output;

a filtering element; and

at least one measurement node for obtaining an input measurement indicative of a pressure change from the input to the output of the exhaust gas particulate filter.

21. The exhaust gas particulate filter of claim 20 further comprising:

a first pressure sensor generating a pressure reading at the input; and

a second pressure sensor generating a pressure reading at the output;

wherein, the pressure reading at the input and the pressure reading at the output are utilized for the input measurement of the measurement node.