Engine control system and method with lean catalyst and particulate filter

• US 6,237,326 B1
• Filed: 08/24/1999
• Issued: 05/29/2001
• Est. Priority Date: 08/24/1999
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Russell, John David
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): TRAN, DIEM T
• Application Number:
  US09/382,363
• Time in Patent Office: 644 Days
• Field of Search: 60/295, 60/297, 60/311, 60/274, 55/DIG. 10, 55/DIG. 30, 422/177, 422/178, 95/278, 95/295, 95/283
• US Class Current: 60/274
• CPC Class Codes: B01D 53/9431 Processes characterised by a specific device
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: F01N 2430/06 by varying fuel-air ratio, e.g. by enriching fuel-air mixture
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/03 the substance being hydrocarbons, e.g. engine fuel
• 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: F01N 3/0253 adding fuel to exhaust gases
• CPC Class Codes: F01N 9/002 of filter regeneration, e.g. detection of clogging
• CPC Class Codes: F02D 2200/0812 Particle filter loading
• CPC Class Codes: F02D 41/029 the exhaust gas treating apparatus being a particulate filter
• CPC Class Codes: F02D 41/405 with post injections
• CPC Class Codes: Y02C 20/10 of nitrous oxide (N2O)
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y10S 55/30 Exhaust treatment

Abstract

A method for controlling reductant added to an exhaust of an engine having a lean NOx catalyst and a particulate filter adjusts a reductant amount during particulate filter regeneration. The method adjusts the reductant amount to account for reducing agents released from the particulate filter that are experienced by the lean NOx catalyst. In addition, management of particulate filter regeneration is based on both an estimated amount of stored particles and conditions of the lean NOx catalyst. In this way, operation of both the particulate filter and the lean NOx catalyst can be optimized. Also, termination of particulate filter regeneration is determined based on operating conditions.

Claims

1. A method for managing regeneration of a particulate filter communicating with an engine exhaust upstream of a catalyst, the method comprising:

estimating an amount of stored particulates in the particulate filter;

regenerating the particulate filter dependent upon said amount and a condition of the catalyst,

adding a first reductant amount to the exhaust when regenerating the particulate filter; and

adding a second reductant amount to the exhaust otherwise, wherein said first reductant amount is based on a quantity of released reductant from regeneration of the particulate filter.

2. The method recited in claim 1 wherein said condition is a catalyst temperature.

3. The method recited in claim 1 further comprising the steps of:

regenerating the particulate filter by increasing an exhaust temperature when said amount of stored particulates is greater than a predetermined amount; and

discontinuing said regeneration when said catalyst temperature is greater than a preselected value.

4. The method recited in claim 3 wherein said preselected value is a maximum allowable temperature without catalyst degradation.

5. The method recited in claim 1 further comprising the step of regenerating the particulate filter by increasing an exhaust temperature when said amount of stored particulates is greater than a first minimum amount and said catalyst temperature is less than a second minimum value.

6. The method recited in claim 5 wherein said second minimum value is a light off temperature above which maximum catalyst efficiency is achievable.

7. The method recited in claim 1 further comprising the steps of:

regenerating the particulate filter by increasing an exhaust temperature when said amount of stored particulates is greater than a predetermined amount; and

discontinuing said regeneration when an exhaust temperature that would be experienced during non-regeneration conditions is below a first preselected value and said stored particulate amount is below a second preselected value.

8. The method recited in claim 7 wherein said exhaust temperature represents a particulate filter temperature that would be experienced during non-regeneration conditions.

9. The method recited in claim 1 further comprising the step of regenerating the particulate filter based on said amount and a temperature of the particulate filter.

10. The method recited in claim 1 further comprising the step of regenerating the particulate filter by increasing an exhaust temperature when said amount of stored particulates is greater than a first minimum amount and said catalyst temperature is greater than a first threshold value.

11. The method recited in claim 1 wherein said catalyst is a lean NOx catalyst capable of reducing NOx in an oxygen rich environment.

12. The method recited in claim 1 wherein said first reductant amount is based on an increased catalyst temperature from heat generated by regeneration of the particulate filter.

13. A method for managing regeneration of a particulate filter communicating with an engine exhaust upstream of an emission control device, the method comprising:

estimating an amount of stored particulates in the particulate filter;

regenerating the particulate filter when said amount is greater than a first predetermined amount and based on an emission control device operating condition, wherein said regeneration further comprises;

regenerating the particulate filter when said amount of stored particulates is greater than a first predetermined amount;

regenerating the particulate filter when said amount of stored particulates is greater than a second predetermined amount and a catalyst temperature is greater than a third predetermined amount; and

regenerating the particulate filter when said amount of stored particulates is greater than a fourth predetermined amount and a catalyst temperature is greater than a fifth predetermined amount.

14. The method recited in claim 13 wherein said emission control device operating condition is a lean NOx catalyst temperature.

15. The method recited in claim 13 wherein said emission control device operating condition is an exhaust temperature.

16. The method recited in claim 13 wherein said emission control device operating condition is a particulate filter temperature.

17. The method recited in claim 15 further comprising the steps of:

discontinuing said regeneration when said catalyst temperature is greater than a first preselected value;

discontinuing said regeneration when said amount of stored particulates is less than a second preselected amount; and

discontinuing said regeneration when an exhaust temperature that would be experienced during non-regeneration conditions is below a third preselected value and said stored particulate amount is below a fourth preselected value.