US5357749A
Expired / Lapsed
US
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Apparatus for controlling exhaust concentration
Assignee: Hitachi Ltd
•
Filing: 1992-05-14
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Granted: 1994-10-25
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Expires: 2012-05-14
Abstract
Abstract A NOx reducing catalyst can most efficiently remove both NOx and HC when concentrations of NOx and HC in exhaust have a specified relationship between them. For this purpose, an apparatus is adapted to control the concentrations of NOx and HC at an upstream of a catalyst to have a specified relationship. Sensors for detecting the concentration of NOx and HC are arranged at an upstream side of the catalyst. Additionally, a device for levelling a quantity of HC discharge is disposed to suppress variation thereof.
Inventors
- 👤 Minoru Ohsuga
- 👤 Toshimichi Minowa
- 👤 Nobuo Kurihara
- 👤 Yoshishige Ohyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:51
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/2006; F01N3/2046; B; B01; B01D; B01D53/00; B01D53/30; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9445; B01D53/9495; F01N3/2013; F01N3/22; F01N3/222; F01N3/24; F01N3/28; F01N3/2882; F01N3/2889; F01N3/2892; F01N9/00; F02; F02B; F02B31/00; F02D; F02D35/00; F02D35/0015; F02D35/0046; F02D41/00; F02D41/0025; F02D41/0047; F02D41/005; F02D41/0052; F02D41/006; F02D41/02; F02D41/14; F02D41/1438; F02D41/1444; F02D41/1459; F02D41/146; F02M; F02M69/00; F02M69/08; F02P; F02P5/00; F02P5/04; F02P5/145; F02P5/15; F02P5/1502; G; G01; G01N; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0011; G01N33/0014; G01N33/0027; G01N33/0036; G01N33/0037; G01N33/0047; F01N2240/00; F01N2240/02; F01N2260/00; F01N2260/02; F01N2260/024; F01N3/30; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12; Y02T10/40
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
120 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to the internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a range where the concentration of the HC is greater than that of the NOx.
Claim 2
Independent Claim
120 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to the internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a range where the concentration of the HC is greater than that of the NOx.
Claim 3
Dependent Claim
27 words
A method according to claim 1, wherein said step of controlling the HC concentration includes a step of controlling the ignition timing of the internal combustion engine.
Claim 4
Dependent Claim
31 words
A method according to claim 1, wherein said step of controlling the HC concentration includes a step of supplying a controlled amount of secondary air upstream of the NOx reducing catalyst.
Claim 5
Independent Claim
111 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range not greater than 1.0.
Claim 6
Independent Claim
111 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range not greater than 1.0.
Claim 7
Dependent Claim
27 words
A method according to claim 4, wherein said step of controlling the HC concentration includes a step of controlling the ignition timing of the internal combustion engine.
Claim 8
Dependent Claim
31 words
A method according to claim 4, wherein said step of controlling the HC concentration includes a step of supplying a controlled amount of secondary air upstream of the NOx reducing catalyst.
Claim 9
Independent Claim
111 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range not less than 0.7.
Claim 10
Independent Claim
111 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range not less than 0.7.
Claim 11
Dependent Claim
27 words
A method according to claim 7, wherein said step of controlling the HC concentration includes a step of controlling the ignition timing of the internal combustion engine.
Claim 12
Dependent Claim
31 words
A method according to claim 7, wherein said step of controlling the HC concentration includes a step of supplying a controlled amount of secondary air upstream of the NOx reducing catalyst.
Claim 13
Independent Claim
125 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range between a first predetermined value not less than 1.0 and a second predetermined value not greater than 0.70.
Claim 14
Independent Claim
125 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range between a first predetermined value not less than 1.0 and a second predetermined value not greater than 0.70.
Claim 15
Dependent Claim
27 words
A method according to claim 10, wherein said step of controlling the HC concentration includes a step of controlling the ignition timing of the internal combustion engine.
Claim 16
Dependent Claim
31 words
A method according to claim 10, wherein said step of controlling the HC concentration includes a step of supplying a controlled amount of secondary air upstream of the NOx reducing catalyst.
Claim 17
Independent Claim
141 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range of values where the concentration of the HC is greater than that of the NOx; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range in response to the comparison.
Claim 18
Independent Claim
141 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range of values where the concentration of the HC is greater than that of the NOx; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range in response to the comparison.
Claim 19
Dependent Claim
27 words
A method according to claim 13, wherein said step of controlling the HC concentration includes a step of controlling the ignition timing of the internal combustion engine.
Claim 20
Dependent Claim
31 words
A method according to claim 13, wherein said step of controlling the HC concentration includes a step of supplying a controlled amount of secondary air upstream of the NOx reducing catalyst.
Claim 21
Independent Claim
137 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range of values where the NOx/HC value is not greater than 1.0; and controlling, in response to the comparison, the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range.
Claim 22
Independent Claim
137 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range of values where the NOx/HC value is not greater than 1.0; and controlling, in response to the comparison, the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range.
Claim 23
Dependent Claim
27 words
A method according to claim 16, wherein said step of controlling the HC concentration includes a step of controlling the ignition timing of the internal combustion engine.
Claim 24
Dependent Claim
31 words
A method according to claim 16, wherein said step of controlling the HC concentration includes a step of supplying a controlled amount of secondary air upstream of the NOx reducing catalyst.
Claim 25
Independent Claim
135 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range where the NOx/HC value is not less than 0.7; and controlling, in response to the comparison, the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range.
Claim 26
Independent Claim
135 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range where the NOx/HC value is not less than 0.7; and controlling, in response to the comparison, the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range.
Claim 27
Dependent Claim
27 words
A method according to claim 19, wherein said step of controlling the HC concentration includes a step of controlling the ignition timing of the internal combustion engine.
Claim 28
Dependent Claim
31 words
A method according to claim 19, wherein said step of controlling the HC concentration includes a step of supplying a controlled amount of secondary air upstream of the NOx reducing catalyst.
Claim 29
Independent Claim
144 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range between a first predetermined value not less than 1.0 and a second predetermined value not greater than 0.7; and controlling, in response to the comparison, the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range.
Claim 30
Independent Claim
144 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; detecting a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst; comparing the detected NOx/HC value with a predetermined range between a first predetermined value not less than 1.0 and a second predetermined value not greater than 0.7; and controlling, in response to the comparison, the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the detected NOx/HC value falls within the predetermined range.
Claim 31
Independent Claim
128 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; determining whether a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range where the concentration of HC is greater than that of NOx; and modifying a current air-fuel ratio to a leaner air-fuel ratio in a case where the NOx/HC has been determined to fall within the predetermined range.
Claim 32
Independent Claim
128 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; determining whether a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range where the concentration of HC is greater than that of NOx; and modifying a current air-fuel ratio to a leaner air-fuel ratio in a case where the NOx/HC has been determined to fall within the predetermined range.
Claim 33
Independent Claim
165 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; determining whether a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range where the concentration of HC is greater than that of NOx; modifying a current air-fuel ratio to a leaner air-fuel ratio in a case where the NOx/HC has been determined to fall within the predetermined range; and modifying, in a case where the NOx/Hc has been determined not to fall within the predetermined range, the current air-fuel ratio to a new air-fuel ratio which causes the NOx/HC ratio to fall within the predetermined range.
Claim 34
Independent Claim
165 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; determining whether a concentration ratio NOx/HC in the exhaust gas flowing into the NOx reducing catalyst falls within a predetermined range where the concentration of HC is greater than that of NOx; modifying a current air-fuel ratio to a leaner air-fuel ratio in a case where the NOx/HC has been determined to fall within the predetermined range; and modifying, in a case where the NOx/Hc has been determined not to fall within the predetermined range, the current air-fuel ratio to a new air-fuel ratio which causes the NOx/HC ratio to fall within the predetermined range.
Claim 35
Independent Claim
103 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the concentration of HC is greater than the concentration of NOx in the exhaust gas.
Claim 36
Independent Claim
103 words
A method of controlling the efficiency of reducing NOx in an exhaust gas issued from an internal combustion engine, by a NOx reducing catalyst disposed in an exhaust system of the internal combustion engine, through which the exhaust gas of oxidizing atmosphere passes, comprising: controlling an air-fuel mixture, supplied to internal combustion engine, at a level leaner than a theoretical air-fuel ratio, but not leaner than a lean combustion limit; and controlling the concentration of HC in the exhaust gas flowing into the NOx reducing catalyst so that the concentration of HC is greater than the concentration of NOx in the exhaust gas.
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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) | 1997-10-24 | 1998-04-25 | 1998-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-24 | 2002-04-25 | 2002-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-10-24 | 2006-04-25 | 2006-10-25 | $7700.00 | Window Closed / Lapsed |