IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0833129
(2004-04-28)
|
등록번호 |
US-7275363
(2007-10-02)
|
우선권정보 |
JP-2003-166046(2003-06-11) |
발명자
/ 주소 |
- Miura,Manabu
- Kitahara,Yasuhisa
- Shirakawa,Takashi
- Yasuhara,Kousuke
|
출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
4 인용 특허 :
13 |
초록
▼
In exhaust gas purifying apparatus and method for an internal combustion engine, a degree of a performance deterioration of an NOx trap catalyst is determined on the basis of a detected air-fuel ratio variation time difference, at the performance deterioration determination of the NOx trap catalyst,
In exhaust gas purifying apparatus and method for an internal combustion engine, a degree of a performance deterioration of an NOx trap catalyst is determined on the basis of a detected air-fuel ratio variation time difference, at the performance deterioration determination of the NOx trap catalyst, the degree of the performance deterioration with at least one of correcting factors of a quantity of NOx trapped by means of the NOx trap catalyst, a reducing agent supply quantity by which a reducing agent is supplied to the NOx trap catalyst, and catalyst temperature which is a temperature of the NOx trap catalyst, and at least one of the correcting factors is reflected on the determination of the degree of the performance deterioration of the NOx trap catalyst.
대표청구항
▼
What is claimed is: 1. An exhaust gas purifying apparatus for an internal combustion engine, comprising: an NOx trap catalyst trapping NOx in the exhaust gas when an air-fuel ratio of the exhaust gas flowing thereinto is lean and discharging the trapped NOx when the air-fuel ratio of the exhaust ga
What is claimed is: 1. An exhaust gas purifying apparatus for an internal combustion engine, comprising: an NOx trap catalyst trapping NOx in the exhaust gas when an air-fuel ratio of the exhaust gas flowing thereinto is lean and discharging the trapped NOx when the air-fuel ratio of the exhaust gas flowing thereinto is rich; a rich controlling section that performs a rich control to richen the air-fuel ratio flowing into an NOx trap catalyst; a first time point specifying section that specifies a first time point at which the air-fuel ratio of the exhaust gas at an upstream side of the NOx trap catalyst has reached a first predetermined value indicating a rich air-fuel ratio; a second time point specifying section that specifices a second time point at which the air-fuel ratio of the exhaust gas at a downstream side of the NOx trap catalyst has reached a second predetermined value indicating a rich air-fuel ratio; an air-fuel ratio variation time difference detecting section that detects a time duration from the first time point to the second time point in a form of an air-fuel ratio variation time difference; and a performance deterioration determining section that determines a degree of a performance deterioration of the NOx trap catalyst on the basis of the detected air-fuel ratio variation time difference, the performance deterioration determining section determining the degree of the performance deterioration with at least one correcting factor selected from the group consisting of a quantity of NOx trapped by means of the NOx trap catalyst, a reducing agent supply quantity by which a reducing agent is supplied to the NOx trap catalyst, and catalyst temperature which is a temperature of the NOx trap catalyst, at least one of the correcting factors being reflected on the determination of the degree of the performance deterioration of the NOx trap catalyst, wherein the performance deterioration determining section determines whether the NOx trap catalyst reaches a performance deterioration level by comparing the detected air-fuel ratio variation time difference with a reference time difference having a length in time varied in accordance with a predetermined degree of the performance deterioration of the NOx trap catalyst and the reference time difference is corrected by the correcting factor. 2. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, wherein the first time point specifying section includes a section that detects the air-fuel ratio of the exhaust gas at the upstream side of the NOx trap catalyst and the second time point specifying section includes a section that detects the air-fuel ratio of the exhaust gas at the downstream side of the NOx trap catalyst. 3. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, wherein the performance deterioration determining section provides a correction factor for the NOx trap quantity when the rich control is started. 4. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, further comprising a section that determines a timing at which a regeneration of NOx in the NOx trap catalyst is carried out by discharging the trapped NOx from the NOx trap catalyst and wherein the rich control section performs the rich control when NOx is regenerated. 5. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, further comprising a section that releases a poisoning of the NOx trap catalyst by discharging a trapped sulfide compound and wherein the performance deterioration determining section comprises a section that determines the degree of the performance deterioration of the NOx trap catalyst only during an elapse of a predetermined period of time from a time at which the poisoning of the NOx trap catalyst is released. 6. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, wherein each of the correcting factors is reflected on the degree of the performance deterioration of the NOx trap catalyst. 7. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, wherein the performance deterioration determining section includes a section that detects an NOx trap quantity as a calculated value obtained by accumulating the quantity of NOx exhausted per unit time from the engine when the NOx trap quantity is the correction factor. 8. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 7, wherein the deterioration determining section includes a section that detects an intake air quantity of the engine and the NOx trap quantity detecting section detects the NOx trap quantity of the NOx trap catalyst on the basis the detected intake air quantity. 9. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 7, wherein the performance deterioration determining section includes a section that detects a concentration of NOx in the exhaust gas and the NOx trap quantity detecting section calculates the NOx trap quantity exhausted per unit of time on the basis of the detected concentration of NOx. 10. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 7, wherein the performance deterioration determining section includes a section that detects a temperature of the NOx trap catalyst and each quantity of NOx is corrected in accordance with the detected temperature when the quantity of NOx exhausted per unit time is accumulated. 11. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, wherein the deterioration determining section sets the reducing agent supply quantity per unit time at a time of a start of a rich control to be the correcting factor. 12. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 11, wherein the performance deterioration determining section includes a section that detects the air-fuel ratio of the exhaust gas at an upstream side of the NOx trap catalyst and a section that detects a reducing agent supply quantity as a calculated value based on the detected air-fuel ratio. 13. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, wherein the performance deterioration determining section determines whether the NOx trap catalyst reaches a performance deterioration level by comparing the detected air-fuel ratio variation time difference with a reference time difference having a length in time varied in accordance with a predetermined degree of the performance deterioration of the NOx trap catalyst and the reference time difference is corrected by each of the correcting factors. 14. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 6, wherein the performance deterioration determining section comprises: a reference time difference correcting section that corrects the reference time difference (ΔTcal) in accordance with each of the correcting factors as follows: ΔTcal=ΔTbase횞Hosnox횞Hosunburnt횞Hostbed, wherein ΔTbase denotes a basic fixed value of the reference time difference, Hosnox denotes a first correction factor according to the quantity of NOx trapped in the NOx trap catalyst, Hosunburnt denotes a second correction factor according to the quantity of reducing agent in the NOx trap catalyst, and Hostbed denotes a third correction factor according to the temperature of the NOx trap catalyst. 15. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 14, wherein the first correction factor of Hosnox is set to one when the trap quantity of NOx in the NOx trap catalyst indicates a predetermined value and, as the trap quantity is increased, the value of the first correction factor Hosnox becomes larger. 16. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 14, wherein the second correction factor of Hosunburnt is set to one when the supply quantity of the reducing agent to the NOx trap catalyst indicates a predetermined value and, as the supply quantity of the reducing agent becomes larger, the value of the second correction factor Hosunburnt becomes smaller. 17. An exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 14, wherein the third correction factor of Hostbed is set to one when the temperature of the NOx trap catalyst indicates a predetermined value, as the temperature becomes increased, the value of third correction factor Hostbed becomes decreased, and, when the temperature of the NOx trap catalyst becomes another predetermined value which is higher than the predetermined value, the value of the third correction factor Hostbed becomes a constant value smaller than one. 18. An exhaust gas purifying apparatus for an internal combustion engine, comprising: NOx trap catalyst means for trapping NOx in the exhaust gas when an air-fuel ratio of the exhaust gas flowing thereinto is lean and for discharging the trapped NOx when the air-fuel ratio of the exhaust gas flowing thereinto is rich; rich controlling means for performing a rich control to richen the air-fuel ratio flowing into the NOx trap catalyst means; first time point specifying means for specifying a first time point at which the air-fuel ratio of the exhaust gas at an upstream side of the NOx trap catalyst has reached a first predetermined value indicating a rich air-fuel ratio; second time point specifying means for specifying a second time point at which the air-fuel ratio of the exhaust gas at a downstream side of the NOx trap catalyst means has reached a second predetermined value indicating a rich air-fuel ratio; air-fuel ratio variation time difference detecting means for detecting a time duration from the first time point to the second time point in a form of an air-fuel ratio variation time difference; and performance deterioration determining means for determining a degree of a performance deterioration of the NOx trap catalyst on the basis of the detected air-fuel ratio variation time difference, the performance deterioration determining means determining the degree of the performance deterioration with at least one correcting factor selected from the group consisting of a quantity of NOx trapped by means of the NOx trap catalyst means, a reducing agent supply quantity by which a reducing agent is supplied to the NOx trap catalyst means, and catalyst temperature which is a temperature of the NOx trap catalyst means, at least one of the correcting factors being reflected on the determination of the degree of the performance deterioration of the NOx trap catalyst means, wherein the performance deterioration determining means determines whether the NOx trap catalyst reaches a performance deterioration level by comparing the detected air-fuel ratio variation time difference with a reference time difference having a length in time varied in accordance with a predetermined degree of the performance deterioration of the NOx trap catalyst means and the reference time difference is corrected by the correcting factor. 19. An exhaust gas purifying method for an internal combustion engine, comprising: providing an NOx trap catalyst trapping NOx in the exhaust gas when an air-fuel ratio of the exhaust gas flowing thereinto is lean and discharging the trapped NOx when the air-fuel ratio of the exhaust gas flowing thereinto is rich; performing a rich control to richen the air-fuel ratio flowing into an NOx trap catalyst; specifying a first time point at which the air-fuel ratio of the exhaust gas at an upstream side of the NOx trap catalyst has reached a first predetermined value indicating a rich air-fuel ratio; specifying a second time point at which the air-fuel ratio of the exhaust gas at a downstream side of the NOx trap catalyst has reached a second predetermined value indicating a rich air-fuel ratio; detecting a time duration from the first time point to the second time point in a form of an air-fuel ratio variation time difference; and determining a degree of a performance deterioration of the NOx trap catalyst on the basis of the detected air-fuel ratio variation time difference, at the performance deterioration determination, determining the degree of the performance deterioration with at least one correcting factor selected from the group consisting of a quantity of NOx trapped by means of the NOx trap catalyst, a reducing agent supply quantity by which a reducing agent is supplied to the NOx trap catalyst, and catalyst temperature which is a temperature of the NOx trap catalyst, at least one of the correcting factors being reflected on the determination of the degree of the performance deterioration of the NOx trap catalyst, wherein, at the performance deterioration determining, determining whether the NOx trap catalyst reaches a performance deterioration level by comparing the detected air-fuel ratio variation time difference with a reference time difference having a length in time varied in accordance with a predetermined degree of the performance deterioration of the NOx trap catalyst is made and the reference time difference is corrected by the correcting factor.
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