System for diagnosing reagent solution quality and emissions catalyst degradation

• US 20050287034A1
• Filed: 06/24/2004
• Published: 12/29/2005
• Est. Priority Date: 06/24/2004
• Status: Active Grant

• Current Assignee: Eric B. Andrews, Wills, J Stephen
• Original Assignee: Eric B. Andrews, Wills, J Stephen
• Inventors: Wills, J. Stephen, Andrews, Eric B.
• Granted Patent: US 7,067,319 B2
• Time in Patent Office: Days
• US Class Current: 422/52
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2550/03 of sorbing activity of adsorbents or absorbents
• CPC Class Codes: F01N 2550/05 Systems for adding substances into exhaust
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F02B 37/18 by bypassing exhaust from the inlet to the outlet of turbine or to the atmosphere
• CPC Class Codes: F02B 37/22 by varying cross-section of exhaust passages or air passages , e.g. by throttling turbine inlets or outlets or by varying effective number of guide conduits F02B37/24 takes precedence
• CPC Class Codes: F02B 37/24 by using pumps or turbines with adjustable guide vanes
• CPC Class Codes: F02D 41/1462 with determination means using an estimation
• CPC Class Codes: F02D 41/1465 with determination means using an estimation
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y10T 436/12 Condition responsive control
• CPC Class Codes: Y10T 436/173845 Amine and quaternary ammonium
• CPC Class Codes: Y10T 436/175383 Ammonia
• CPC Class Codes: Y10T 436/177692 Oxides of nitrogen
• CPC Class Codes: Y10T 436/179228 Both nitrogen oxide and dioxide

Abstract

A system for determining a reagent solution quality indicator includes a reagent solution source for supplying the reagent solution to an emissions catalyst configured to receive a NOx-containing gas therethrough, means for determining a flow rate of NOx reduced from the gas by the catalyst, means for determining a flow rate of the reagent solution into the catalyst, and a control circuit determining the reagent solution quality indicator as a function of the NOx flow rate and the reagent solution flow rate. The system may additionally be configured to diagnose reagent solution quality by configuring the control circuit to monitor the reagent solution quality indicator over time and produce a fault value if the reagent solution quality indicator crosses a reagent quality indicator threshold, and to diagnose the catalyst by producing another fault value if the catalyst capacity point falls outside of a catalyst capacity point threshold.

Claims

1. A system for determining a reagent solution quality indicator, comprising:

a reagent solution source for supplying the reagent solution to an emissions catalyst configured to receive a NOx-containing gas therethrough,

means for determining a NOx flow rate corresponding to a flow rate of NOx reduced from the gas by the emissions catalyst,

means for determining a reagent solution flow rate corresponding to a flow rate of the reagent solution into the emissions catalyst, and

a control circuit determining the reagent solution quality indicator as a function of the NOx flow rate and the reagent solution flow rate.

2. The system of claim 1 wherein the means for determining a NOx flow rate includes:

means for determining a flow rate of NOx entering the emissions catalyst, and

means for determining a flow rate of NOx exiting the emissions catalyst,

wherein the control circuit is configured to determine a difference between the flow rate of NOx entering the emissions catalyst and the flow rate of NOx exiting the emissions catalyst, and to determine a normalized NOx flow rate as the difference normalized to a maximum NOx flow rate value.

3. The system of claim 2 wherein the control circuit is configured to determine a normalized reagent solution flow rate as the reagent solution flow rate value normalized to a maximum reagent solution flow rate value.

4. The system of claim 3 wherein the control circuit is configured to determine the reagent solution quality indicator as a slope of the normalized NOx flow rate and the normalized reagent solution flow rate over time.

5. The system of claim 1 further including an internal combustion having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust gas,

and wherein the emissions catalyst is coupled to the exhaust manifold such that the engine exhaust gas flows therethrough.

6. A method of determining a reagent solution quality indicator, comprising:

determining a NOx flow rate corresponding to a flow rate of NOx reduced from a NOx-containing gas passing through an emissions catalyst,

determining a reagent solution flow rate corresponding to a flow rate of the reagent solution into the emissions catalyst, and

determining the reagent solution quality indicator as a function of the NOx flow rate and the reagent solution flow rate.

7. The method of claim 6 wherein the act of determining a NOx flow rate includes:

determining a flow rate of NOx entering the emissions catalyst,

determining a flow rate of NOx exiting the emissions catalyst,

computing a difference between the flow rate of NOx entering the emissions catalyst and the flow rate of NOx exiting the emissions catalyst, and

determining the NOx flow rate as the difference normalized to a maximum NOx flow rate value.

8. The method of claim 7 wherein the act of determining a reagent solution flow rate includes normalizing the reagent solution flow rate to a maximum reagent flow rate value.

9. The method of claim 8 wherein the act of determining the reagent solution quality indicator includes determining a slope of normalized values of the NOx flow rate and the reagent solution flow rate over time.

10. A system for diagnosing reagent solution quality, comprising:

a reagent solution source for supplying the reagent solution to an emissions catalyst configured to receive a NOx-containing gas therethrough,

means for determining a reagent solution quality indicator as a function of a flow rate of NOx reduced from the gas by the emissions catalyst and a flow rate of the reagent solution into the emissions catalyst, and

a control circuit monitoring the reagent solution quality indicator and producing a fault value if the reagent solution quality indicator crosses a reagent quality indicator threshold.

11. The system of claim 10 wherein the control circuit is configured to produce the fault value only if the reagent solution quality indicator has extended beyond the reagent solution quality indicator value for a predefined time period.

12. The system of claim 10 further including an indicator lamp,

and wherein the control circuit is configured to activate the indicator lamp if the reagent solution quality indicator crosses the reagent quality indicator threshold.

13. The system of claim 12 wherein the control circuit is configured to activate

the indicator lamp only if the reagent solution quality indicator has extended beyond the reagent solution quality indicator value for a predefined time period.

14. The system of claim 10 further including an internal combustion having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust gas,

and wherein the emissions catalyst is coupled to the exhaust manifold such that the engine exhaust gas flows therethrough.

15. The system of claim 14 wherein the control circuit is configured to command a derate of the engine if the reagent solution quality indicator crosses the reagent quality indicator threshold.

16. The system of claim 15 wherein the control circuit is configured to command a derate of the engine only if the reagent solution quality indicator has extended beyond the reagent solution quality indicator value for a predefined time period.

17. The system of claim 14 wherein the control circuit is configured to command a shut down of the engine if the reagent solution quality indicator crosses the reagent quality indicator threshold.

18. The system of claim 17 wherein the control circuit is configured to command a shut down of the engine only if the reagent solution quality indicator has extended beyond the reagent solution quality indicator value for a predefined time period.

19. The system of claim 14 wherein the control circuit is configured to command activation of an auxiliary emissions control device if the reagent solution quality indicator crosses the reagent quality indicator threshold.

20. The system of claim 13 wherein the control circuit is configured to command activation of the auxiliary emissions control device only if the reagent solution quality indicator has extended beyond the reagent solution quality indicator value for a predefined time period.

21. The system of claim 10 wherein the reagent solution quality indicator threshold is a poor reagent solution quality threshold and the fault value is a poor reagent solution quality flag,

and wherein the control circuit is configured to set the poor reagent solution quality flag if the reagent solution quality indicator crosses the poor reagent solution quality threshold.

22. The system of claim 21 wherein the control circuit is configured to set the poor reagent solution quality flag only if the reagent solution quality indicator extends beyond the poor reagent solution quality threshold for a predefined time period.

23. The system of claim 10 wherein the reagent solution quality indicator threshold is a failed reagent solution quality threshold and the fault value is a failed reagent solution quality flag,

and wherein the control circuit is configured to set the failed reagent solution quality flag if the reagent solution quality indicator crosses the failed reagent solution quality threshold.

24. The system of claim 23 wherein the control circuit is configured to set the failed reagent solution quality flag only if the reagent solution quality indicator extends beyond the failed reagent solution quality threshold for a predefined time period.

25. The system of claim 10 wherein the reagent solution quality indicator threshold is a high reagent solution quality threshold and the fault value is a high reagent solution quality flag,

and wherein the control circuit is configured to set the high reagent solution quality flag if the reagent solution quality indicator crosses the high reagent solution quality threshold.

26. The system of claim 25 wherein the control circuit is configured to set the high reagent solution quality flag only if the reagent solution quality indicator extends beyond the high reagent solution quality threshold for a predefined time period.

27. The system of claim 10 wherein the control circuit is configured to produce a reagent solution change value if the reagent solution quality indicator changes by more than a change threshold.

28. The system of claim 27 wherein the control circuit is configured to produce the reagent solution change value only if the reagent solution quality indicator changes by more than the change threshold for a predefined time period.

29. A method of diagnosing reagent solution quality, comprising:

determining a reagent solution quality indicator as a function of a flow rate of NOx reduced from a NOx-containing gas passing through an emissions catalyst and a flow rate of the reagent solution into the emissions catalyst, and

monitoring the reagent solution quality indicator, and

producing a fault value if the reagent solution quality indicator crosses a reagent quality indicator threshold.

30. The method of claim 29 wherein the act of producing a fault value includes producing the fault value only if the reagent solution quality indicator extends beyond the reagent quality indicator threshold for a predefined time period.

31. The method of claim 29 further including activating an indicator lamp if the reagent quality indicator crosses the reagent quality indicator threshold.

32. The method of claim 31 wherein the act of activating an indicator lamp includes activating the indicator lamp only if the reagent solution quality indicator extends beyond the reagent quality indicator threshold for a predefined time period.

33. The method of claim 29 further including an internal combustion engine having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust, the emissions catalyst coupled to the exhaust manifold so that the engine exhaust flows therethrough,

and wherein the method further includes derating the engine if the reagent quality indicator crosses the reagent quality indicator threshold.

34. The method of claim 33 wherein the act of derating the engine includes derating the engine only if the reagent solution quality indicator extends beyond the reagent quality indicator threshold for a predefined time period.

35. The method of claim 29 further including an internal combustion engine having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust, the emissions catalyst coupled to the exhaust manifold so that the engine exhaust flows therethrough,

and wherein the method further includes shutting down the engine if the reagent quality indicator crosses the reagent quality indicator threshold.

36. The method of claim 35 wherein the act of shutting down the engine includes shutting down the engine only if the reagent solution quality indicator extends beyond the reagent quality indicator threshold for a predefined time period.

37. The method of claim 29 further including an internal combustion engine having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust, the emissions catalyst coupled to the exhaust manifold so that the engine exhaust flows therethrough,

and wherein the method further includes activating an auxiliary emissions control device if the reagent quality indicator crosses the reagent quality indicator threshold.

38. The method of claim 37 wherein the act of activating an auxiliary emissions control device includes activating the auxiliary emissions control device only if the reagent solution quality indicator extends beyond the reagent quality indicator threshold for a predefined time period.

39. The method of claim 29 wherein the reagent solution quality indicator threshold is a poor reagent solution quality threshold and the fault value is a poor reagent solution quality flag,

and wherein the act of producing a fault value includes setting the poor reagent solution quality flag if the reagent solution quality indicator crosses the poor reagent solution quality threshold.

40. The method of claim 39 wherein the act of setting the poor reagent solution quality flag includes setting the poor reagent solution quality flag only if the reagent solution quality indicator extends beyond the poor reagent solution quality threshold for a predefined time period.

41. The method of claim 29 wherein the reagent solution quality indicator threshold is a failed reagent solution quality threshold and the fault value is a failed reagent solution quality flag,

and wherein the act of producing a fault value includes setting the failed reagent solution quality flag if the reagent solution quality indicator crosses the failed reagent solution quality threshold.

42. The method of claim 41 wherein the act of setting the failed reagent solution quality flag includes setting the failed reagent solution quality flag only if the reagent solution quality indicator extends beyond the failed reagent solution quality threshold for a predefined time period.

43. The method of claim 29 wherein the reagent solution quality indicator threshold is a high reagent solution quality threshold and the fault value is a high reagent solution quality flag,

and wherein the act of producing a fault value includes setting the high reagent solution quality flag if the reagent solution quality indicator crosses the high reagent solution quality threshold.

44. The method of claim 43 wherein the act of setting the high reagent solution quality flag includes setting the high reagent solution quality flag only if the reagent solution quality indicator extends beyond the high reagent solution quality threshold for a predefined time period.

45. The method of claim 29 further including producing a reagent solution change value if the reagent solution quality indicator changes by more than a change threshold.

46. The method of claim 45 wherein the act of producing a reagent solution change value includes producing the reagent solution change value only if the reagent solution quality indicator changes by more than the change threshold for a predefined time period.

47. A system for diagnosing an emissions catalyst having a NOx-containing gas passing therethrough, comprising:

a reagent solution source for supplying the reagent solution to the emissions catalyst,

means for determining a reagent solution flow rate corresponding to a flow rate of the reagent solution into the emissions catalyst,

means for determining a NOx flow rate corresponding to a flow rate of NOx reduced from the gas by the emissions catalyst, and

a control circuit determining a catalyst capacity point, beyond which a reaction capacity of the emissions catalyst is exceeded, as a function of the NOx flow rate and the reagent solution flow rate, the control circuit producing a fault value if the catalyst capacity point falls beyond a predefined catalyst capacity threshold.

48. The system of claim 47 wherein the control circuit is configured to monitor the catalyst capacity point and produce the fault value only if the catalyst capacity point falls beyond the predefined catalyst capacity threshold a sufficient number of times over a predefined time period.

49. The system of claim 47 further including an indicator lamp,

and wherein the control circuit is configured to activate the indicator lamp if the catalyst capacity point falls beyond the predefined catalyst capacity threshold.

50. The system of claim 47 further including an internal combustion engine having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust gas,

and wherein the emissions catalyst is coupled to the exhaust manifold such that the engine exhaust gas flows therethrough.

51. The system of claim 50 wherein the control circuit is configured to command a derate of the engine if the catalyst capacity point falls beyond the predefined catalyst capacity threshold.

52. The system of claim 50 wherein the control circuit is configured to command a shut down of the engine if the catalyst capacity point falls beyond the predefined catalyst capacity threshold.

53. The system of claim 50 wherein the control circuit is configured to command activation of an auxiliary emissions control device if the catalyst capacity point falls beyond the predefined catalyst capacity threshold.

54. The system of claim 47 wherein the predefined catalyst capacity threshold is a catalyst capacity failure threshold and the fault value is an emissions catalyst failure flag,

and wherein the control circuit is configured to set the emissions catalyst failure flag if the catalyst capacity point falls beyond the catalyst capacity failure threshold.

55. The system of claim 54 wherein the control circuit is further configured to set an emissions catalyst degraded flag if the catalyst capacity point falls within the catalyst capacity failure threshold but beyond a catalyst capacity degraded threshold.

56. The system of claim 47 wherein the predefined catalyst capacity threshold is a catalyst capacity degraded threshold and the fault value is an emissions catalyst degraded flag,

and wherein the control circuit is configured to set the emissions catalyst degraded flag if the catalyst capacity point falls beyond the catalyst capacity degraded threshold.

57. The system of claim 47 wherein the catalyst capacity point corresponds to the reagent solution flow rate at which the catalyst capacity point occurs, and wherein the predefined catalyst capacity threshold is a predefined reagent solution flow rate threshold.

58. The system of claim 47 wherein the catalyst capacity point corresponds to the NOx flow rate at which the catalyst capacity point occurs, and wherein the predefined catalyst capacity threshold is a predefined NOx flow rate threshold.

59. A method of diagnosing an emissions catalyst having a NOx-containing gas passing therethrough, comprising:

determining a NOx flow rate corresponding to a flow rate of NOx reduced from the gas by the emissions catalyst,

determining a reagent solution flow rate corresponding to a flow rate of reagent solution into the emissions catalyst,

determining a catalyst capacity point, beyond which a reaction capacity of the emissions catalyst is exceeded, as a function of the NOx flow rate and the reagent solution flow rate, and

producing a fault value if the catalyst capacity point falls beyond a predefined catalyst capacity threshold.

60. The method of claim 59 wherein the act of producing the fault value includes producing the fault value only if the catalyst capacity point falls beyond the predefined catalyst capacity threshold a sufficient number of times over a predefined time period.

61. The method of claim 59 further including activating an indicator lamp if the catalyst capacity point falls beyond a predefined catalyst capacity threshold.

62. The method of claim 59 further including an internal combustion engine having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust, the emissions catalyst coupled to the exhaust manifold so that the engine exhaust flows therethrough,

and wherein the method further includes derating the engine if the catalyst capacity point falls beyond a predefined catalyst capacity threshold.

63. The method of claim 59 further including an internal combustion engine having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust, the emissions catalyst coupled to the exhaust manifold so that the engine exhaust flows therethrough,

and wherein the method further includes shutting down the engine if the catalyst capacity point falls beyond a predefined catalyst capacity threshold.

64. The method of claim 59 further including an internal combustion engine having an exhaust manifold producing the NOx-containing gas in the form of engine exhaust, the emissions catalyst coupled to the exhaust manifold so that the engine exhaust flows therethrough,

and wherein the method further includes activating an auxiliary emissions control device if the catalyst capacity point falls beyond a predefined catalyst capacity threshold.

65. The method of claim 59 wherein the predefined catalyst capacity threshold is a catalyst capacity failure threshold and the fault value is an emissions catalyst failure flag,

and wherein the act of producing a fault value includes setting the emissions catalyst failure flag if the catalyst capacity point falls beyond the catalyst capacity failure threshold.

66. The method of claim 65 further including setting an emissions catalyst degraded flag if the catalyst capacity point falls within the catalyst capacity failure threshold but beyond a catalyst capacity degraded threshold.

67. The method of claim 59 wherein the predefined catalyst capacity threshold is a catalyst capacity degraded threshold and the fault value is an emissions catalyst degraded flag,

and wherein the act of producing a fault value includes setting the emissions catalyst degraded flag if the catalyst capacity point falls beyond the catalyst capacity degraded threshold.

68. The method of claim 67 wherein the catalyst capacity point corresponds to the reagent solution flow rate at which the catalyst capacity point occurs, and wherein the predefined catalyst capacity threshold is a predefined reagent solution flow rate threshold.

69. The method of claim 59 wherein the catalyst capacity point corresponds to the NOx flow rate at which the catalyst capacity point occurs, and wherein the predefined catalyst capacity threshold is a predefined NOx flow rate threshold.