US5778667A
Expired / Lapsed
US
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Method and a device for purifying combustion exhaust gas
Assignee: Toyota Motor Corp
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Filing: 1997-06-16
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Granted: 1998-07-14
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Expires: 2017-06-16
Abstract
Abstract In the present invention, the No. 1 cylinder of an engine is connected to a first exhaust passage and the No. 2 to No. 4 cylinders are connected to a second exhaust passage. A three-way catalyst and a NO X absorbent are disposed in the first and second exhaust passage, respectively. A denitrating catalyst is disposed in a common exhaust passage to which the first and second exhaust passage merge. The NO X absorbent absorbs NO X when the No. 2 to No. 4 cylinders are operated at a lean air-fuel ratio, and is regenerated, i.e., releases and reduces the absorbed NO X when the No. 2 to No. 4 cylinders are operated at a rich air-fuel ratio. However, NO X , without being reduced, is released from the NO X absorbent during a short period at the beginning of the regenerating operation. In the present invention, the No. 1 cylinder is operated at a rich air-fuel ratio during the short period at the beginning of the regenerating operation in order to produce NH 3 at the three-way catalyst. Therefore, when NO X without being reduced is released from the NO X absorbent and flows into the denitrating catalyst on the common exhaust passage, NH 3 produced at the three-way catalyst is also supplied to the denitrating catalyst. Thus, NO X released from the NO X absorbent at the beginning of the regenerating operation is reduced at the denitrating catalyst by NH 3 produced at the three-way catalyst.
Inventors
- 👤 Yukio Kinugasa
- 👤 Takaaki Itou
- 👤 Naoto Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:38
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/206; F01N3/2066; F01N3/2073; B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9481; B01D53/9495; F01N13/00; F01N13/009; F01N13/011; F01N3/0807; F01N3/0828; F01N3/0842; F01N3/0871; F01N3/2053; F01N9/00; B01D2251/00; B01D2251/20; B01D2251/206; B01D2251/2062; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/9418; B01D53/9445; B01D53/945; F01N2240/00; F01N2240/25; F01N2250/00; F01N2250/12; F01N2610/00; F01N2610/02; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12; Y02T10/40
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
271 words
A method for purifying combustion exhaust gas comprising: a step for contacting an exhaust gas having a lean air-fuel ratio with a NO X absorbent to cause the NO X absorbent to absorb NO X in the exhaust gas, wherein said NO X absorbent absorbs NO X in an exhaust gas when an air-fuel ratio of an exhaust gas is lean and releases the absorbed NO X when an air-fuel ratio of an exhaust gas becomes rich and wherein said NO X absorbent releases the absorbed NO X without reducing it during a short period after an air-fuel ratio of an exhaust gas is changed from a lean air-fuel ratio to a rich air-fuel ratio and releases the absorbed NO X after reducing it to N 2 and H 2 O after said short period has lapsed; a step for causing the air-fuel ratio of the exhaust gas contacting said NO X absorbent to be a rich air-fuel ratio in order to make the NO X absorbent release the absorbed NO X ; a step for supplying NH 3 to the exhaust gas after it contacts said NO X absorbent during said short period in which the NO X absorbed in the NO X absorbent is released without being reduced; and a step for contacting the exhaust gas after NH 3 is added with a NO X purifying means which reduces NO X in the exhaust gas by reacting the NO X with NH 3 in the exhaust gas to, thereby, reduce the NO X released from the NO X absorbent in said short period by said NO X purifying means.
Claim 2
Independent Claim
271 words
A method for purifying combustion exhaust gas comprising: a step for contacting an exhaust gas having a lean air-fuel ratio with a NO X absorbent to cause the NO X absorbent to absorb NO X in the exhaust gas, wherein said NO X absorbent absorbs NO X in an exhaust gas when an air-fuel ratio of an exhaust gas is lean and releases the absorbed NO X when an air-fuel ratio of an exhaust gas becomes rich and wherein said NO X absorbent releases the absorbed NO X without reducing it during a short period after an air-fuel ratio of an exhaust gas is changed from a lean air-fuel ratio to a rich air-fuel ratio and releases the absorbed NO X after reducing it to N 2 and H 2 O after said short period has lapsed; a step for causing the air-fuel ratio of the exhaust gas contacting said NO X absorbent to be a rich air-fuel ratio in order to make the NO X absorbent release the absorbed NO X ; a step for supplying NH 3 to the exhaust gas after it contacts said NO X absorbent during said short period in which the NO X absorbed in the NO X absorbent is released without being reduced; and a step for contacting the exhaust gas after NH 3 is added with a NO X purifying means which reduces NO X in the exhaust gas by reacting the NO X with NH 3 in the exhaust gas to, thereby, reduce the NO X released from the NO X absorbent in said short period by said NO X purifying means.
Claim 3
Independent Claim
298 words
A device for purifying a combustion exhaust gas comprising: a NO X absorbent disposed on an exhaust gas passage, said NO X absorbent absorbs NO X in an exhaust gas when an air-fuel ratio of an exhaust gas is lean and releases the absorbed NO X when an air-fuel ratio of an exhaust gas becomes rich and wherein said NO X absorbent releases the absorbed NO X without reducing it during a short period after the air-fuel ratio of the exhaust gas is changed from a lean air-fuel ratio to a rich air-fuel ratio and releases the absorbed NO X after reducing it to N 2 and H 2 O after said short period has lapsed; NO X purifying means disposed on the exhaust gas passage downstream of the NO X absorbent and for reducing NO X in an exhaust gas by reacting it with NH 3 ; air-fuel ratio adjusting means for adjusting the air-fuel ratio of the exhaust gas flowing into the NO X absorbent to a lean air-fuel ratio in order to make the NO X absorbent absorb NO X in the exhaust gas and for adjusting the air-fuel ratio of the exhaust gas flowing into the NO X absorbent to a rich air-fuel ratio in order to make the NO X absorbent release the absorbed NO X ; and a NH 3 supply means for supplying NH 3 to the exhaust gas in the exhaust gas passage at the portion between the NO X absorbent and the NO X purifying means during said short period in which the NO X absorbed in the NO X absorbent is released without being reduced, whereby the NO X purifying means reduces the NO X released from the NO X absorbent without being reduced during said short period.
Claim 4
Independent Claim
298 words
A device for purifying a combustion exhaust gas comprising: a NO X absorbent disposed on an exhaust gas passage, said NO X absorbent absorbs NO X in an exhaust gas when an air-fuel ratio of an exhaust gas is lean and releases the absorbed NO X when an air-fuel ratio of an exhaust gas becomes rich and wherein said NO X absorbent releases the absorbed NO X without reducing it during a short period after the air-fuel ratio of the exhaust gas is changed from a lean air-fuel ratio to a rich air-fuel ratio and releases the absorbed NO X after reducing it to N 2 and H 2 O after said short period has lapsed; NO X purifying means disposed on the exhaust gas passage downstream of the NO X absorbent and for reducing NO X in an exhaust gas by reacting it with NH 3 ; air-fuel ratio adjusting means for adjusting the air-fuel ratio of the exhaust gas flowing into the NO X absorbent to a lean air-fuel ratio in order to make the NO X absorbent absorb NO X in the exhaust gas and for adjusting the air-fuel ratio of the exhaust gas flowing into the NO X absorbent to a rich air-fuel ratio in order to make the NO X absorbent release the absorbed NO X ; and a NH 3 supply means for supplying NH 3 to the exhaust gas in the exhaust gas passage at the portion between the NO X absorbent and the NO X purifying means during said short period in which the NO X absorbed in the NO X absorbent is released without being reduced, whereby the NO X purifying means reduces the NO X released from the NO X absorbent without being reduced during said short period.
Claim 5
Independent Claim
376 words
A device for purifying an exhaust gas from an internal combustion engine having a plurality of cylinder groups, each of the cylinder groups consists of one or more cylinders, said device comprising: a first exhaust gas passage connected to one cylinder group of the engine; a second exhaust gas passage connected to another cylinder group of the engine; a common exhaust gas passage to which the first and the second exhaust gas passages merge; a NH 3 generating means disposed on the first exhaust gas passage for converting at least a part of NO X in an exhaust gas to NH 3 when an air-fuel ratio of an exhaust gas is a rich air-fuel ratio; a NO X absorbent disposed on the second exhaust gas passage, said NO X absorbent absorbs NO X in an exhaust gas when an air-fuel ratio of an exhaust gas is lean and releases the absorbed NO X when an air-fuel ratio of an exhaust gas becomes rich and, wherein said NO X absorbent releases the absorbed NO X without reducing it during a short period after the air-fuel ratio of the exhaust gas is changed from a lean air-fuel ratio to a rich air-fuel ratio and releases the absorbed NO X after reducing it to N 2 and H 2 O after said short period lapses; NO X purifying means disposed on the common exhaust gas passage and for reaction NO X with NH 3 in an exhaust gas to, thereby, reduce NO X in the exhaust gas; a first air-fuel ratio adjusting means for operating the cylinder group connected to the second exhaust gas passage at a lean air-fuel ratio in order to make the NO X absorbent absorb NO X in the exhaust gas, and operation the same at a rich air-fuel ratio in order to make the NO X absorbent release the absorbed NO X ; a second air-fuel ratio adjusting means for operating the cylinder group connected to the first exhaust gas passage at a rich air-fuel ratio during said short period in which the NO X absorbed in the NO X absorbent is released without being reduced to, thereby, reduces the NO X released from the NO X absorbent by said NO X purifying means.
Claim 6
Independent Claim
376 words
A device for purifying an exhaust gas from an internal combustion engine having a plurality of cylinder groups, each of the cylinder groups consists of one or more cylinders, said device comprising: a first exhaust gas passage connected to one cylinder group of the engine; a second exhaust gas passage connected to another cylinder group of the engine; a common exhaust gas passage to which the first and the second exhaust gas passages merge; a NH 3 generating means disposed on the first exhaust gas passage for converting at least a part of NO X in an exhaust gas to NH 3 when an air-fuel ratio of an exhaust gas is a rich air-fuel ratio; a NO X absorbent disposed on the second exhaust gas passage, said NO X absorbent absorbs NO X in an exhaust gas when an air-fuel ratio of an exhaust gas is lean and releases the absorbed NO X when an air-fuel ratio of an exhaust gas becomes rich and, wherein said NO X absorbent releases the absorbed NO X without reducing it during a short period after the air-fuel ratio of the exhaust gas is changed from a lean air-fuel ratio to a rich air-fuel ratio and releases the absorbed NO X after reducing it to N 2 and H 2 O after said short period lapses; NO X purifying means disposed on the common exhaust gas passage and for reaction NO X with NH 3 in an exhaust gas to, thereby, reduce NO X in the exhaust gas; a first air-fuel ratio adjusting means for operating the cylinder group connected to the second exhaust gas passage at a lean air-fuel ratio in order to make the NO X absorbent absorb NO X in the exhaust gas, and operation the same at a rich air-fuel ratio in order to make the NO X absorbent release the absorbed NO X ; a second air-fuel ratio adjusting means for operating the cylinder group connected to the first exhaust gas passage at a rich air-fuel ratio during said short period in which the NO X absorbed in the NO X absorbent is released without being reduced to, thereby, reduces the NO X released from the NO X absorbent by said NO X purifying means.
Claim 7
Dependent Claim
107 words
A device according to claim 3, wherein said second air-fuel ratio adjusting means operates the cylinder group connected to the first exhaust gas passage at a rich air-fuel ratio during a predetermined period after said first air-fuel ratio adjusting means changes the air-fuel ratio of the cylinder group connected to the second exhaust gas passage from a lean air-fuel ratio to a rich air-fuel ratio, and wherein said second air-fuel ratio adjusting means changes the air-fuel ratio of the cylinder group connected to the first exhaust gas passage from a rich air-fuel ratio to a lean or a stoichiometric air-fuel ratio when said predetermined period has lapsed.
Claim 8
Dependent Claim
170 words
A device according to claim 3, further comprising: exhaust switching means for connecting said one cylinder group to the first exhaust gas passage and the second exhaust gas passage selectively; switching control means for controlling the exhaust switching means and the second air-fuel ratio adjusting means in such a manner that: (a) when said first air-fuel ratio adjusting means operates said another cylinder group at a lean air-fuel ratio, the exhaust switching means connects said one cylinder group to the second exhaust gas passage and the second air-fuel ratio adjusting means operates said one cylinder group at a lean air-fuel ratio; and (b) when said first air-fuel ratio adjusting means changes the air-fuel ratio of said another cylinder group from a lean air-fuel ratio to a rich air-fuel ratio, the exhaust switching means connects said one cylinder group to the first exhaust gas passage and said second air-fuel ratio adjusting means switches the air-fuel ratio of said one cylinder group from a lean air-fuel ratio to a rich air-fuel ratio.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-07-13 | 2002-01-12 | 2002-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-07-13 | 2006-01-12 | 2006-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-07-13 | 2010-01-12 | 2010-07-14 | $7700.00 | Window Closed / Lapsed |