US6173704B1
Expired / Lapsed
US
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Exhaust gas purification system of internal combustion engine
Assignee: Honda Motor Co Ltd
•
Filing: 1998-08-13
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Granted: 2001-01-16
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Expires: 2018-08-13
Abstract
Abstract A system for purifying exhaust gas of an internal combustion engine 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. An EGR mechanism is provided for recirculating a part of the exhaust gas to an intake system of the engine, and is controlled such that a ratio of unsaturated and/or aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is at or above a predetermined value. The EGR mechanism is further controlled such that oxygen concentration in the exhaust gas is below a prescribed value. An injection timing mechanism is controlled for the same purpose. With this arrangement, the system improves the NOx purification rate of the catalyst.
Inventors
- 👤 Isao Komoriya
- 👤 Ken Ogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:10
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/0025; F02D41/0047; F02D41/0065; F02D41/0072; B; B01; B01D; B01D53/00; B01D53/34; B01D53/74; B01D53/86; B01D53/8696; B01D53/90; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9431; B01D53/9495; F02D41/02; F02D41/021; F02D41/0235; F02D41/14; F02D41/1438; F02D41/1473; F02D41/1475; B01D2251/00; B01D2251/20; B01D2251/208; F01; F01N; F01N2330/00; F01N2330/06; F02D41/1444; F02D41/1454; F02D41/1456; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12; Y02T10/40
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
171 words
A system for purifying exhaust gas of an internal combustion engine 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, comprising: an EGR mechanism for recirculating a part of the exhaust gas to an intake system of the engine; an EGR control means for controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value; and an injection timing control means for controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 2
Independent Claim
171 words
A system for purifying exhaust gas of an internal combustion engine 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, comprising: an EGR mechanism for recirculating a part of the exhaust gas to an intake system of the engine; an EGR control means for controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value; and an injection timing control means for controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 3
Dependent Claim
47 words
A system according to claim 1 , further including: an air/fuel ratio determining means for determining a desired air/fuel ratio to be supplied to the engine, wherein said injection timing control means controls the timing of fuel injection in response to at least the desired air/fuel ratio.
Claim 4
Dependent Claim
98 words
A system according to claim 2 , wherein said injection timing control means compares the desired air/fuel ratio with a predetermined air/fuel ratio and, when the desired air/fuel ratio exceeds the predetermined air/fuel ratio in a direction leaner than a stoichiometric air/fuel ratio, controls the timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 5
Dependent Claim
18 words
A system according to claim 1 , wherein the catalyst is a selective-reduction type nitrogen oxide reduction catalyst.
Claim 6
Dependent Claim
32 words
A system according to claim 4 , wherein the catalyst is composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance).
Claim 7
Dependent Claim
122 words
A system according to claim 5 , further comprising: an air/fuel ratio control means for controlling an air/fuel ratio to be supplied to the engine to a value leaner than a stoichiometric air/fuel ratio; and an injection timing control means for controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that the fuel injection is effected to avoid a period during which an intake valve and an exhaust valve are open in order that a ratio of unsaturated hydrocarbon concentration, aromatic either one of hydrocarbon concentration, and a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 8
Dependent Claim
18 words
A system according to claim 6 , wherein the catalyst is a selective-reduction type nitrogen oxide reduction catalyst.
Claim 9
Dependent Claim
32 words
A system according to claim 7 , wherein the catalyst is composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance).
Claim 10
Independent Claim
201 words
A system for purifying exhaust gas of an internal combustion engine 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, comprising: an EGR mechanism for recirculating a part of the exhaust gas to an intake system of the engine; an EGR control means for controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value; and: an injection timing control means for controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value and wherein said ERG control means further controls the EGR mechanism in accordance with a predetermined characteristic such that oxygen concentration in the exhaust gas is below a prescribed value.
Claim 11
Independent Claim
201 words
A system for purifying exhaust gas of an internal combustion engine 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, comprising: an EGR mechanism for recirculating a part of the exhaust gas to an intake system of the engine; an EGR control means for controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value; and: an injection timing control means for controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value and wherein said ERG control means further controls the EGR mechanism in accordance with a predetermined characteristic such that oxygen concentration in the exhaust gas is below a prescribed value.
Claim 12
Dependent Claim
47 words
A system according to claim 9 , further including: an air/fuel ratio determining means for determining a desired air/fuel ratio to be supplied to the engine, wherein said injection timing control means controls the timing of fuel injection in response to at least the desired air/fuel ratio.
Claim 13
Dependent Claim
98 words
A system according to claim 10 , wherein said injection timing control means compares the desired air/fuel ratio with a predetermined air/fuel ratio and, when the desired air/fuel ratio exceeds the predetermined air/fuel ratio in a direction leaner than a stoichiometric air/fuel ratio, controls the timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 14
Dependent Claim
47 words
A system according to claim 11 , further including: an air/fuel ratio determining means for determining a desired air/fuel ratio to be supplied to the engine, wherein said air/fuel ratio control means controls the timing of fuel injection in response to at least the desired air/fuel ratio.
Claim 15
Dependent Claim
98 words
A system according to claim 12 , wherein said air/fuel ratio control means compares the desired air/fuel ratio with a predetermined air/fuel ratio and, when the desired air/fuel ratio exceeds the predetermined air/fuel ratio in a direction leaner than a stoichiometric air/fuel ratio, controls the timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 16
Independent Claim
148 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine is in an oxidizing state, comprising the steps of: recirculating a part of the exhaust gas to an intake system of the engine; and controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value and controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 17
Independent Claim
148 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine is in an oxidizing state, comprising the steps of: recirculating a part of the exhaust gas to an intake system of the engine; and controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value and controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 18
Dependent Claim
35 words
A method according to claim 14 further including: determining a desired air/fuel ratio to be supplied to the engine; and controlling the timing of fuel injection in response to at least the desired air/fuel ratio.
Claim 19
Dependent Claim
92 words
A method according to claim 14 , comparing the desired air/fuel ratio with a predetermined air/fuel ratio and, when the desired air/fuel ratio exceeds the predetermined air/fuel ratio in a direction leaner than a stoichiometric air/fuel ratio, controlling the timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 20
Dependent Claim
110 words
A method according to claim 14 , further comprising the steps of: controlling an air/fuel ratio to be supplied to the engine to a value leaner than a stoichiometric air/fuel ratio; and controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that the fuel injection is effected to avoid a period during which an intake valve and an exhaust valve is open in order that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 21
Dependent Claim
36 words
A method according to claim 17 , further including: determining a desired air/fuel ratio to be supplied to the engine; and controlling the timing of fuel injection in response to at least the desired air/fuel ratio.
Claim 22
Dependent Claim
92 words
A method according to claim 18 , comparing the desired air/fuel ratio with a predetermined air/fuel ratio and, when the desired air/fuel ratio exceeds the predetermined air/fuel ratio in a direction leaner than a stoichiometric air/fuel ratio, controlling the timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 23
Dependent Claim
18 words
A method according to claim 17 , wherein the catalyst is a selective-reduction type nitrogen oxide reduction catalyst.
Claim 24
Dependent Claim
19 words
A method according to claim 14 , wherein said method is a computer program embodied on a computer-readable medium.
Claim 25
Dependent Claim
110 words
A method according to claim 21 , further comprising the steps of: controlling an air/fuel ratio to be supplied to the engine to a value leaner than a stoichiometric air/fuel ratio; and controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that the fuel injection is effected to avoid a period during which an intake valve and an exhaust valve is open in order that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 26
Independent Claim
173 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine is in an oxidizing state, comprising the steps of: recirculating a part of the exhaust gas to an intake system of the engine; and controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value and controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value; wherein the ERG mechanism is controlled in accordance with a predetermined characteristic such that oxygen concentration in the exhaust gas is below a prescribed value.
Claim 27
Independent Claim
173 words
A method of purifying exhaust gas of an internal combustion engine having a catalyst in an exhaust system of the engine is in an oxidizing state, comprising the steps of: recirculating a part of the exhaust gas to an intake system of the engine; and controlling the EGR mechanism in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value and controlling a timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value; wherein the ERG mechanism is controlled in accordance with a predetermined characteristic such that oxygen concentration in the exhaust gas is below a prescribed value.
Claim 28
Dependent Claim
36 words
A method according to claim 23 , further including: determining a desired air/fuel ratio to be supplied to the engine; and controlling the timing of fuel injection in response to at least the desired air/fuel ratio.
Claim 29
Dependent Claim
92 words
A method according to claim 24 , comparing the desired air/fuel ratio with a predetermined air/fuel ratio and, when the desired air/fuel ratio exceeds the predetermined air/fuel ratio in a direction leaner than a stoichiometric air/fuel ratio, controlling the timing of fuel injection to be supplied to the engine in accordance with a predetermined characteristic such that a ratio of unsaturated hydrocarbon concentration, aromatic hydrocarbon concentration, or a combination of unsaturated and aromatic hydrocarbon concentration to nitrogen oxide concentration in the exhaust gas is greater than or equal to a predetermined value.
Claim 30
Dependent Claim
18 words
A method according to claim 23 , wherein the catalyst is a selective-reduction type nitrogen oxide reduction catalyst.
Claim 31
Dependent Claim
32 words
A method according to claim 26 , wherein the catalyst is composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance).
Claim 32
Dependent Claim
32 words
A method according to claim 27 , wherein the catalyst is composed of a heat resistant inorganic oxide substrate (monolith) and iridium borne on the substrate (monolith) as an active material (substance).
References Cited (Backward Citations)
EP0496526A1
Cited
EP0503882A1
Cited
US5357749A
Cited
US5571763A
Cited
US5487268A
Cited
US5326735A
Cited
US5402641A
Cited
US5613481A
Cited
US5768887A
Cited
JPH08309186A
Cited
US5950595A
Cited
US5848580A
Cited
US5988151A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-01-16 | 2004-07-17 | 2005-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-01-16 | 2008-07-17 | 2009-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-01-16 | 2012-07-17 | 2013-01-16 | $7700.00 | Window Closed / Lapsed |