METHOD FOR ESTIMATING SOOT LOADING IN A DIESEL PARTICULATE FILTER, AND ENGINE AND AFTERTREATMENT SYSTEM

• US 20110162352A1
• Filed: 09/10/2008
• Published: 07/07/2011
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: AB Volvo
• Original Assignee: MACK Trucks Incorporated (AB Volvo)
• Inventors: Svensson, Kenth I., Tai, Chun
• Granted Patent: US 8,646,257 B2
• Time in Patent Office: Days
• US Class Current: 60/297
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• 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 2240/14 a fuel burner
• CPC Class Codes: F01N 2240/16 an electric heater, i.e. a resistance heater
• CPC Class Codes: F01N 2550/04 Filtering activity of particulate filters
• CPC Class Codes: F01N 2560/08 the means being a pressure sensor
• CPC Class Codes: F01N 2560/14 having more than one sensor of one kind
• CPC Class Codes: F01N 2900/0418 using integration or an accumulated value within an elapsed period
• CPC Class Codes: F01N 2900/16 said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
• CPC Class Codes: F01N 2900/1606 Particle filter loading or soot amount
• CPC Class Codes: F01N 3/025 using fuel burner or by adding fuel to exhaust
• CPC Class Codes: F01N 3/027 using electric or magnetic heating means
• CPC Class Codes: F01N 9/002 of filter regeneration, e.g. detection of clogging
• CPC Class Codes: F01N 9/005 using models instead of sensors to determine operating characteristics of exhaust systems, e.g. calculating catalyst temperature instead of measuring it directly
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for estimating soot loading of a diesel particulate filter includes establishing a soot loading model for estimating soot loading of a nominal diesel particulate filter, adjusting the soot loading model for a subject filter to account for differences between the nominal filter and the subject filter, and estimating soot loading of the subject filter using the adjusted soot loading model. An engine with a diesel particulate filter is also provided.

Claims

1. A method for estimating soot loading of a diesel particulate filter, comprising:

establishing a soot loading model for estimating soot loading of a nominal diesel particulate filter;

adjusting the soot loading model for a subject filter to account for differences between the nominal filter and the subject filter; and

estimating soot loading of the subject filter using the adjusted soot loading model.

2. The method as set forth in claim 1, comprising initiating an active regeneration cycle when the estimated soot loading of the subject filter exceeds a predetermined level.

3. The method as set forth in claim 1, wherein the soot loading model estimates soot loading as a function of pressure drop across the nominal filter.

4. The method as set forth in claim 3, comprising monitoring pressure drop across the subject filter to obtain at least one pressure drop measurement and estimating soot loading of the subject filter as a function of the at least one pressure drop measurement.

5. The method as set forth in claim 1, comprising determining differences between the nominal filter and the subject filter based on a de-greened nominal filter and a de-greened subject filter.

6. The method as set forth in claim 5, comprising determining differences between the nominal filter and the subject filter based on a new subject filter.

7. The method as set forth in claim 5, comprising determining differences between the nominal filter and the subject filter after active regeneration of the subject filter.

8. The method as set forth in claim 1, wherein establishing the model comprises establishing a first curve of nominal pressure drop across the nominal filter versus volume flow rate, the method comprising defining a second curve of measured pressure drop values across the subject filter versus volume flow rate through the subject filter, and wherein adjusting the soot loading model comprises multiplying values on the second curve by a factor such that the second curve approximates the first curve.

9. The method as set forth in claim 8, wherein the adjusted soot loading model estimates soot loading as a function of the measured pressure drop across the subject filter.

10. The method as set forth in claim 1, wherein establishing the model comprises establishing nominal pressure drop across the nominal filter at a plurality of volume flow rates, the adjusting step comprises measuring pressure drop across the subject filter at the volume flow rates and multiplying the measured pressure drops at the volume flow rates by a factor such that the measured pressure drops across the subject filter approximate values of the nominal pressure drop at the volume flow rates.

11. The method as set forth in claim 10, wherein the estimating step comprises multiplying a measured pressure drop at a volume flow rate by a factor corresponding to the volume flow rate to obtain an adjusted pressure drop, and comparing the adjusted pressure drop to a nominal pressure drop at the volume flow rate.

12. The method as set forth in claim 1, wherein an error (E(t)) of the soot loading model for the subject filter at time t equals

E(t)=sum(X(t)−

Xbar)/T,

where time t=0, 1, 2, . . . , T

X(t) is a calculated value for soot loading of the subject filter at a given filter condition,

Xbar is a calibrated value for soot loading of the nominal filter at the given filter condition, and at time T, the offset value Z(t) by which the calculated value X(t) can be offset to provide the estimated value Xa(t) for soot loading is represented by the equation;

Z(t)=Z(t−

1)+G*[E(t−

1)−

Z(t−

1)]

where G is a factor corresponding to reliability of soot loading data between time t=0 and time t=T, and the estimated value Xa(t) for soot loading of the subject filter is represented by the equation Xa(t)=X(t)−

Z(t).

13. The method as set forth in claim 1, wherein the soot loading model determines soot loading as a function of pressure drop across at least part of the nominal filter.

14. The method as set forth in claim 13, wherein the soot loading model is adjusted for the subject filter by multiplying w_wall by a factor so that the equation accurately calculates zero soot loading in the subject filter.

15. The method as set forth in claim 13, wherein the soot loading model is adjusted for the subject filter by multiplying k_wall by a factor so that the equation accurately calculates zero soot loading in the subject filter.

16. A diesel engine with an exhaust aftertreatment system, comprising:

a subject diesel particulate filter;

a controller, the controller comprising a soot loading model for estimating soot loading of a nominal diesel particulate filter, the controller being adapted to adjust the soot loading model for the subject filter to account for differences between the nominal filter and the subject filter, and being adapted to estimate soot loading of the subject filter using the adjusted soot loading model.

17. The diesel engine with exhaust aftertreatment system as set forth in claim 16, wherein the subject filter is a catalyzed filter.

18. The diesel engine with exhaust aftertreatment system as set forth in claim 16, comprising a heater for active regeneration of the subject filter.

19. The diesel engine with exhaust aftertreatment system as set forth in claim 18, comprising a sensor for sensing at least one condition of the subject filter and sending a signal to the controller to initiate active regeneration in response to the signal.

20. The diesel engine with exhaust aftertreatment system as set forth in claim 19, wherein the at least one condition is at least one of pressure drop, fuel consumption, distance traveled, and operating time.