Claims
- 1. A method of controlling an exhaust gas system of an internal combustion engine which operates mainly under a lean condition, which system comprises a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst; said method comprising the steps of:
- (a) switching temporarily the operation condition of said internal combustion engine into a stoichiometric condition or a rich condition so that the nitrogen oxide adsorbed to said nitrogen oxide reducing catalyst is detached or decomposed when an output of the nitrogen oxide sensor reaches a predetermined level,
- (b) returning the operational condition back to a lean condition when an electromotive force, or a pumping current of a first pumping cell, of the nitrogen oxide sensor reaches a predetermined level.
- 2. A method of controlling an exhaust gas system of an internal combustion engine which operates mainly under a lean condition, which system comprises a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst; said method comprising the steps of:
- (a) injecting a fuel upstream of said nitrogen oxide reducing catalyst so that the nitrogen oxide adsorbed to said nitrogen oxide reducing catalyst is detached or decomposed when an output of the nitrogen oxide sensor reaches a predetermined level, and
- (b) returning the operational condition back to a lean condition when an electromotive force, or a pumping current of a first pumping cell, of the nitrogen oxide sensor reaches a predetermined level.
- 3. A method of detecting deterioration of a catalyst usable for an exhaust gas system of an internal combustion engine which operates mainly under a lean condition; said system comprising a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst characterized in that deterioration of the catalyst is detected based on a length of a period between the step (a) and the step (b) in claim 1.
- 4. A method of detecting deterioration of a catalyst usable for an exhaust gas system of an internal combustion engine which operates mainly under a lean condition; said system comprising a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst characterized in that deterioration of the catalyst is detected based on a length of a period between the step (a) and the step (b) in claim 2.
- 5. A method of detecting deterioration of a catalyst/adsorption means, usable for an exhaust gas system of an internal combustion engine which operates mainly under a lean condition; said system comprising a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst, characterized in that deterioration of the catalyst is detected based on a length of a period between the step (a) and the step (b) in claim 1.
- 6. A method of detecting deterioration of a catalyst/adsorption means, usable for an exhaust gas system of an internal combustion engine which operates mainly under a lean condition; said system comprising a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst, characterized in that deterioration of the catalyst is detected based on a length of a period between the step (a) and the step (b) in claim 2.
Priority Claims (2)
Number |
Date |
Country |
Kind |
8-161219 |
Jun 1996 |
JPX |
|
9-139022 |
May 1997 |
JPX |
|
Parent Case Info
This is a continuation of application Ser. No. 08/876,285 filed Jun. 16, 1997, now U.S. Pat. No. 5,953,907.
US Referenced Citations (6)
Non-Patent Literature Citations (1)
Entry |
"Evaluation of NOx Storage Catalysts as an Effective System for NOx Removal from the Exhaust Gas of Leanburn Gasoline Engines"; M.S. Brogan et al. |
Continuations (1)
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Number |
Date |
Country |
Parent |
876285 |
Jun 1997 |
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