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US5778667A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and a device for purifying combustion exhaust gas

Assignee: Toyota Motor Corp
•
Filing: 1997-06-16
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Granted: 1998-07-14
•
Expires: 2017-06-16
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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 10:00
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.

References Cited (Backward Citations)

US3810361A Cited
US3767764A Cited
US3953576A Cited
US4393031A Cited
US4321792A Cited
US4854123A Cited
US5021227A Cited
JPH05131118A Cited
US5609026A Cited
US5410873A Cited
JPH04365920A Cited
US5473887A Cited
WO1993007363A1 Cited
JPH06108827A Cited
US5367875A Cited
US5406790A Cited
US5628186A Cited
JPH06330741A Cited
US5540047A Cited
JPH084522A Cited
US5605042A Cited

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

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