Process and system for controlling the mixture composition for a spark ignition otto engine with an NOx storage catalyst during a regeneration phase

• US 20030056500A1
• Filed: 08/15/2002
• Published: 03/27/2003
• Est. Priority Date: 08/16/2001
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG, Dr. Ing. H.C.F. Porsche Ag, DaimlerChrysler AG (Mercedes-Benz Group AG)
• Original Assignee: Dr. Ing. H.C.F. Porsche Ag
• Inventors: Schmeling, Ulf-Peter, Huynh, Ngoc-Hoa, Gerl, Peter, Salzer, Lorenz
• Granted Patent: US 6,871,492 B2
• Time in Patent Office: Days
• US Class Current: 60/295
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F01N 2570/14 Nitrogen oxides
• CPC Class Codes: F01N 3/0814 combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F01N 3/0885 Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps
• CPC Class Codes: F02D 2041/141 using a feed-forward control element
• CPC Class Codes: F02D 41/0275 the exhaust gas treating apparatus being a NOx trap or adsorbent
• CPC Class Codes: F02D 41/1463 of the exhaust gases downstream of exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/405 with post injections
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A process and a system are used for controlling the mixture composition for an Otto engine with an NO_x storage catalyst during a regeneration phase. The process includes controlling, to the value of one, a λ-value (λ_M) of an exhaust gas fed to the NO_x storage catalyst during a regeneration phase as a function of a λ-value (λ_K) of an exhaust gas emitted by the NO_x storage catalyst. The system includes a control device for controlling, to the value of one, a λ-value (λ_M) of the exhaust gas fed to the NO_x storage catalyst during the regeneration phase as a function of the λ-value (λ_K) of the exhaust gas emitted by the NO_x storage catalyst.

Claims

1. A process for controlling the mixture composition for an Otto engine with an NO_x storage catalyst during a regeneration phase, the process comprising controlling, to the value of one, a λ

-value (λ

_M) of an exhaust gas fed to the NO_x storage catalyst during a regeneration phase as a function of a λ

-value (λ

_K) of an exhaust gas emitted by the NO_x storage catalyst.

2. The process according to claim 1, wherein the step of controlling the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst includes controlling the λ

-value (λ

_M) such that the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst does not fall under a value of one or falls only insignificantly under a value of one.

3. The process according to claim 2, further comprising initiating the regeneration phase when an NO_x content of the exhaust gas emitted by the NO_x storage catalyst exceeds a predetermined value.

4. The process according to claim 3, further comprising terminating the regeneration phase under at least one of two conditions:

(1) when a signal of an NO_x sensor disposed behind the NO_x storage catalyst exceeds a predetermined value and (2) when a rate of change of the signal exceeds a predetermined value.

5. The process according to claim 3, further comprising terminating the regeneration phase when the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined value.

6. The process according to claim 5, further comprising controlling the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst at the beginning of the regeneration phase to a constant pilot value (λ

_REG), and starting the control of the λ

-value (λ

_K) to the value of one only after the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined intervention value (λ

_i).

7. The process according to claim 6, wherein the step of controlling the λ

-value (λ

_M) of the exhaust gas to a constant pilot value (λ

_REG) includes making a predetermined afterinjection and controlling the λ

-value of the main combustion such that the λ

-value (λ

_M) value of the exhaust gas fed to the NO_x storage catalyst assumes the constant pilot value (λ

_REG).

8. The process according to claim 7, further comprising controlling the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst according to the formula

λ

_M=λ

_REG+k*(λ

_i−

λ

_K)

wherein k is a constant.

9. The process according to claim 1, further comprising initiating the regeneration phase when an NO_x content of the exhaust gas emitted by the NO_x storage catalyst exceeds a predetermined value.

10. The process according to claim 1, further comprising terminating the regeneration phase under at least one of two conditions:

(1) when a signal of an NO_x sensor disposed behind the NO_x storage catalyst exceeds a predetermined value and (2) when a rate of change of the signal exceeds a predetermined value.

11. The process according to claim 1, further comprising terminating the regeneration phase when the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined value.

12. The process according to claim 1, further comprising controlling the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst at the beginning of the regeneration phase to a constant pilot value (λ

_REG), and starting the control of the λ

-value (λ

_K) to the value of one only after the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined intervention value (λ

_i).

13. The process according to claim 12, wherein the step of controlling the λ

-value (λ

_M) of the exhaust gas to a constant pilot value (λ

_REG) includes making a predetermined afterinjection and controlling the λ

-value of the main combustion such that the λ

-value (λ

_M) value of the exhaust gas fed to the NO_x storage catalyst assumes the constant pilot value (λ

_REG).

14. The process according to claim 13, further comprising controlling the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst according to the formula

λ

_M=λ

_REG+k*(λ

_i−

λ

_K)

wherein k is a constant.

15. A system for controlling the mixture composition for an Otto engine having an NO_x storage catalyst during a regeneration phase, the system comprising a control device for controlling, to the value of one, a λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst during the regeneration phase as a function of the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst.

16. The system according to claim 15, wherein the control device controls the λ

-value (λ

_M) such that the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst does not fall under a value of one or falls only insignificantly under a value of one.

17. The system according to claim 16, wherein the control device initiates the regeneration phase when an NO_x content of the exhaust gas emitted by the NO_x storage catalyst exceeds a predetermined value.

18. The system according to claim 17, wherein the control device terminates the regeneration phase under at least one of two conditions:

(1) when a signal of an NO_x sensor disposed behind the NO_x storage catalyst exceeds a predetermined value and (2) when a rate of change of the signal exceeds a predetermined value.

19. The system according to claim 17, wherein the control device terminates the regeneration phase when the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined value.

20. The system according to claim 19, wherein the control device controls the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst at the beginning of the regeneration phase to a constant pilot value (λ

_REG), and starts the control of the λ

-value (λ

_K) to the value of one only after the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined intervention value (λ

_i).

21. The system according to claim 20, wherein the control device makes a predetermined afterinjection and controlling the λ

-value of the main combustion such that the λ

-value (λ

_M) value of the exhaust gas fed to the NO_x storage catalyst assumes the constant pilot value (λ

_REG).

22. The system according to claim 21, wherein the control device controls the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst according to the formula

λ

_M=λ

_REG+k*(λ

_i−

λ

_K)

wherein k is a constant.

23. The system according to claim 15, wherein the control device initiates the regeneration phase when an NO_x content of the exhaust gas emitted by the NO_x storage catalyst exceeds a predetermined value.

24. The system according to claim 15, wherein the control device terminates the regeneration phase under at least one of two conditions:

(1) when a signal of an NO_x sensor disposed behind the NO_x storage catalyst exceeds a predetermined value and (2) when a rate of change of the signal exceeds a predetermined value.

25. The system according to claim 15, wherein the control device terminates the regeneration phase when the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined value.

26. The system according to claim 15, wherein the control device controls the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst at the beginning of the regeneration phase to a constant pilot value (λ

_REG), and starts the control of the λ

-value (λ

_K) to the value of one only after the λ

-value (λ

_K) of the exhaust gas emitted by the NO_x storage catalyst falls below a predetermined intervention value (λ

_i).

27. The system according to claim 26, wherein the control device makes a predetermined afterinjection and controlling the λ

-value of the main combustion such that the λ

-value (λ

_M) value of the exhaust gas fed to the NO_x storage catalyst assumes the constant pilot value (λ

_REG).

28. The system according to claim 27, wherein the control device controls the λ

-value (λ

_M) of the exhaust gas fed to the NO_x storage catalyst according to the formula

λ

_M=λ

_REG+k*(λ

_i−

λ

_K)

wherein k is a constant.