US6089017A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exhaust gas purification system of internal combustion engine
Assignee: Honda Motor Co Ltd
•
Filing: 1998-08-13
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Granted: 2000-07-18
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Expires: 2018-08-13
Abstract
Abstract An engine exhaust gas purification system having a catalyst in an exhaust system of the engine, said catalyst reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state. In the system, engine operating parameters, including at least an engine speed and an engine load, are determined and catalyst temperature is determined, and air/fuel ratio is controlled in response to the detected parameters and the determined catalyst temperature, thereby enabling the catalyst to purify NOx in its optimum temperature characteristic range to achieve enhanced NOx constituent purification performance in an oxidizing environment. Alternatively, the air/fuel ratio is controlled in the stoichiometric or richer direction when the catalyst temperature is high, thereby protecting the catalyst from being damaged. The catalyst is a selective-reduction type nitrogen oxide reduction catalyst.
Inventors
- 👤 Ken Ogawa
- 👤 Isao Komoriya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:11
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/74; B01D53/86; B01D53/8696; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9431; B01D53/9495; F; F02; F02D; F02D41/00; F02D41/02; F02D41/021; F02D41/0235; F02D41/14; F02D41/1438; F02D41/1444; F02D41/1446; F02D41/24; F02D41/2406; F02D41/2425; F02D41/2429; F02D41/2451; F02D41/2454; F02D41/2461; F02D2200/00; F02D2200/02; F02D2200/04; F02D2200/0406; F02D2200/08; F02D2200/0802; F02D2200/0804; F02D2200/70; F02D2200/703; F02D41/0025; F02D41/0047; F02D41/1454; F02D41/1456
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
184 words
A system for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide carrier and iridium borne on the carrier as an active species and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising: engine operating condition detection means for detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; catalyst temperature determining means for determining a temperature of the catalyst; and air/fuel ratio controlling means for controlling an air/fuel ratio, to be supplied to the engine in response to at least one of the detected parameters and the determined temperature of the catalyst, to a value in a lean direction when the determined temperature of the catalyst is within a predetermined range, and to a value in a rich direction, which is not more than a stoichiometric air/fuel ratio, when the determined temperature of the catalyst is outside of the predetermined range.
Claim 2
Independent Claim
184 words
A system for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide carrier and iridium borne on the carrier as an active species and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising: engine operating condition detection means for detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; catalyst temperature determining means for determining a temperature of the catalyst; and air/fuel ratio controlling means for controlling an air/fuel ratio, to be supplied to the engine in response to at least one of the detected parameters and the determined temperature of the catalyst, to a value in a lean direction when the determined temperature of the catalyst is within a predetermined range, and to a value in a rich direction, which is not more than a stoichiometric air/fuel ratio, when the determined temperature of the catalyst is outside of the predetermined range.
Claim 3
Dependent Claim
44 words
A system according to claim 1, wherein said air/fuel ratio control means controls the air/fuel ratio to a value in a rich direction not more than a stoichiometric air/fuel ratio when the determined temperature of the catalyst is not less than a predetermined temperature.
Claim 4
Dependent Claim
35 words
A system according to claim 1, wherein said catalyst temperature determining means determines the temperature of the catalyst by calculating the temperature based on at least one of the detected parameters and the air/fuel ratio.
Claim 5
Dependent Claim
46 words
A system according to claim 3, wherein said catalyst temperature determining means calculates the temperature of the catalyst based on at least a specific heat, a heat transfer coefficient and an exhaust temperature determined based on an engine speed, an engine load and the air/fuel ratio.
Claim 6
Dependent Claim
25 words
A system according to claim 1, wherein said catalyst temperature determining means determines the temperature of the catalyst by detecting the temperature through a sensor.
Claim 7
Independent Claim
174 words
A system for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising: engine operating condition detecting means for detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; catalyst temperature determining means for determining a temperature of the catalyst; discriminating means for discriminating whether an air/fuel ratio to be supplied to the engine is controlled to a value in a lean direction; catalyst temperature comparing means for comparing the temperature of the catalyst with a reference temperature; and lean air/fuel ratio inhibiting means for inhibiting the air/fuel ratio to be controlled in the lean direction when the temperature of the catalyst is not less than the reference temperature.
Claim 8
Independent Claim
174 words
A system for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising: engine operating condition detecting means for detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; catalyst temperature determining means for determining a temperature of the catalyst; discriminating means for discriminating whether an air/fuel ratio to be supplied to the engine is controlled to a value in a lean direction; catalyst temperature comparing means for comparing the temperature of the catalyst with a reference temperature; and lean air/fuel ratio inhibiting means for inhibiting the air/fuel ratio to be controlled in the lean direction when the temperature of the catalyst is not less than the reference temperature.
Claim 9
Dependent Claim
35 words
A system according to claim 6, wherein said catalyst temperature determining means determines the temperature of the catalyst by calculating the temperature based on at least one of the detected parameters and the air/fuel ratio.
Claim 10
Dependent Claim
46 words
A system according to claim 7, wherein said catalyst temperature determining means calculates the temperature of the catalyst based on at least a specific heat, a heat transfer coefficient and an exhaust temperature determined based on an engine speed, an engine load and the air/fuel ratio.
Claim 11
Dependent Claim
25 words
A system according to claim 6, wherein said catalyst temperature determining means determines the temperature of the catalyst by detecting the temperature through a sensor.
Claim 12
Independent Claim
174 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; and controlling an air/fuel ratio, to be supplied to the engine in response to at least one of the detected parameters and the determined temperature of the catalyst, to a value in a lean direction when the determined temperature of the catalyst is within a predetermined range, and to a value in a rich direction, which is not more than a stoichiometric air/fuel ratio, when the determined temperature of the catalyst is outside of the predetermined range.
Claim 13
Independent Claim
174 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; and controlling an air/fuel ratio, to be supplied to the engine in response to at least one of the detected parameters and the determined temperature of the catalyst, to a value in a lean direction when the determined temperature of the catalyst is within a predetermined range, and to a value in a rich direction, which is not more than a stoichiometric air/fuel ratio, when the determined temperature of the catalyst is outside of the predetermined range.
Claim 14
Dependent Claim
38 words
A method according to claim 10, controlling the air/fuel ratio to a value in a rich direction not more than a stoichiometric air/fuel ratio when the determined temperature of the catalyst is not less than a predetermined temperature.
Claim 15
Dependent Claim
29 words
A method according to claim 10, determining the temperature of the catalyst by calculating the temperature based on at least one of the detected parameters and the air/fuel ratio.
Claim 16
Dependent Claim
40 words
A method according to claim 12, calculating the temperature of the catalyst based on at least a specific heat, a heat transfer coefficient and an exhaust temperature determined based on an engine speed, an engine load and the air/fuel ratio.
Claim 17
Dependent Claim
19 words
A method according to claim 10, determining the temperature of the catalyst by detecting the temperature through a sensor.
Claim 18
Independent Claim
151 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active species and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; discriminating whether an air/fuel ratio to be supplied to the engine is controlled to a value in a lean direction; comparing the temperature of the catalyst with a reference temperature; and inhibiting the air/fuel ratio to be controlled in the lean direction when the temperature of the catalyst is not less than the reference temperature.
Claim 19
Independent Claim
151 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reduction type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active species and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; discriminating whether an air/fuel ratio to be supplied to the engine is controlled to a value in a lean direction; comparing the temperature of the catalyst with a reference temperature; and inhibiting the air/fuel ratio to be controlled in the lean direction when the temperature of the catalyst is not less than the reference temperature.
Claim 20
Dependent Claim
29 words
A method according to claim 15, determining the temperature of the catalyst by calculating the temperature based on at least one of the detected parameters and the air/fuel ratio.
Claim 21
Dependent Claim
40 words
A method according to claim 16, calculating the temperature of the catalyst based on at least a specific heat, a heat transfer coefficient and an exhaust temperature determined based on an engine speed, an engine load and the air/fuel ratio.
Claim 22
Dependent Claim
19 words
A method according to claim 15, determining the temperature of the catalyst by detecting the temperature through a sensor.
Claim 23
Dependent Claim
180 words
A computer program embodied on a computer-readable medium for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reducing type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; and controlling an air/fuel ratio, to be supplied to the engine in response to at least one of the detected parameters and the determined temperature of the catalyst, to a value in a lean direction when the determined temperature of the catalyst is within a predetermined range, and to a value in a rich direction, which is not more than a stoichiometric air/fuel ratio, when the determined temperature of the catalyst is outside of the predetermined range.
Claim 24
Dependent Claim
180 words
A computer program embodied on a computer-readable medium for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reducing type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; and controlling an air/fuel ratio, to be supplied to the engine in response to at least one of the detected parameters and the determined temperature of the catalyst, to a value in a lean direction when the determined temperature of the catalyst is within a predetermined range, and to a value in a rich direction, which is not more than a stoichiometric air/fuel ratio, when the determined temperature of the catalyst is outside of the predetermined range.
Claim 25
Dependent Claim
158 words
A computer program embodied on a computer-readable medium for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reducing type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; discriminating whether an air/fuel ratio to be supplied to the engine is controlled to a value in a lean direction; comparing the temperature of the catalyst with a reference temperature; and inhibiting the air/fuel ratio to be controlled in the lean direction when the temperature of the catalyst is not less than the reference temperature.
Claim 26
Dependent Claim
158 words
A computer program embodied on a computer-readable medium for purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine, said catalyst being a selective-reducing type nitrogen oxide reduction catalyst composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance) and reducing nitrogen oxide when exhaust gas generated by the engine is in an oxidizing state, comprising the steps of: detecting parameters, including at least an engine speed and an engine load, indicative of operating conditions of the engine; determining a temperature of the catalyst; discriminating whether an air/fuel ratio to be supplied to the engine is controlled to a value in a lean direction; comparing the temperature of the catalyst with a reference temperature; and inhibiting the air/fuel ratio to be controlled in the lean direction when the temperature of the catalyst is not less than the reference temperature.
References Cited (Backward Citations)
US5158063A
Cited
US5357749A
Cited
US5487268A
Cited
US5326735A
Cited
US5402641A
Cited
EP0591744A1
Cited
US5501074A
Cited
US5544639A
Cited
US5609023A
Cited
US5613360A
Cited
JPH07259625A
Cited
US5678402A
Cited
JPH07305647A
Cited
US5661972A
Cited
US5950419A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-07-18 | 2004-01-17 | 2004-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-07-18 | 2008-01-17 | 2008-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-07-18 | 2012-01-17 | 2012-07-18 | $7700.00 | Window Closed / Lapsed |