US5473887A
Expired / Lapsed
US
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Exhaust purification device of internal combustion engine
Assignee: Toyota Motor Corp
•
Filing: 1992-10-02
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Granted: 1995-12-12
•
Expires: 2012-10-02
Abstract
Abstract An NO x absorbent (18) is disposed in an exhaust passage of an internal combustion engine and the exhaust gas is constantly made to circulate through the NO x absorbent (18) during the operation of the engine. The NO x absorbent (18) absorbs the NO x when the air-fuel ratio of the exhaust gas flowing into the NO x absorbent (18) is lean and releases the absorbed NO x when the air-fuel ratio of the exhaust gas flowing into the NO x absorbent (18) becomes the stoichiometric air-fuel ratio or rich. In the majority of the engine operation region, the lean air-fuel mixture is burned in the combustion chamber (3), and the NO x generated at this time is absorbed into the NO x absorbent (18). The air-fuel ratio of the exhaust gas flowing into the NO x absorbent (18) is periodically made the stoichiometric air-fuel ratio or rich, and the NO x absorbed in the NO x absorbent (18) is released, and simultaneously reduced.
Inventors
- 👤 Shinichi Takeshima
- 👤 Kiyoshi Nakanishi
- 👤 Satoshi Iguchi
- 👤 Toshiaki Tanaka
- 👤 Yasushi Araki
- 👤 Shinya Hirota
- 👤 Kiyoshi Kobashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:58
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F02; F02D; F02D41/00; F02D41/02; F02D41/021; F02D41/0235; F02D41/027; F02D41/0275; B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/9422; F01N13/00; F01N13/009; F01N13/0093; F01N3/0807; F01N3/0828; F01N3/0842; F01N3/101; F01N2240/00; F01N2240/18; F01N2390/00; F01N2390/02; F01N2430/00; F01N2430/06; F01N2610/00; F01N2610/03; F01N3/0871; F02B; F02B1/00; F02B1/02; F02B1/04; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
167 words
An exhaust purification device of an internal combustion engine including an exhaust passage and means for controlling an air-fuel ratio of exhaust gas from the engine, comprising an NO x absorbent disposed within the exhaust passage, wherein the NO x absorbent absorbs NO x included in the exhaust flowing into the NO x absorbent when the air-fuel ratio control means makes the air-fuel ratio of the exhaust gas flowing into the NO x absorbent lean and releases an absorbed NO x when an oxygen concentration in the exhaust gas flowing into the NO x absorbent is lowered, and wherein, at all times while the engine is running, the exhaust gas continuously flows into the NO x absorbent so that the NO x absorbed in the NO x absorbent while the air-fuel ratio of the exhaust gas flowing into the NO x absorbent is lean is released from the NO x absorbent when the oxygen concentration of the exhaust gas flowing into the NO x absorbent is lowered.
Claim 2
Dependent Claim
167 words
An exhaust purification device of an internal combustion engine including an exhaust passage and means for controlling an air-fuel ratio of exhaust gas from the engine, comprising an NO x absorbent disposed within the exhaust passage, wherein the NO x absorbent absorbs NO x included in the exhaust flowing into the NO x absorbent when the air-fuel ratio control means makes the air-fuel ratio of the exhaust gas flowing into the NO x absorbent lean and releases an absorbed NO x when an oxygen concentration in the exhaust gas flowing into the NO x absorbent is lowered, and wherein, at all times while the engine is running, the exhaust gas continuously flows into the NO x absorbent so that the NO x absorbed in the NO x absorbent while the air-fuel ratio of the exhaust gas flowing into the NO x absorbent is lean is released from the NO x absorbent when the oxygen concentration of the exhaust gas flowing into the NO x absorbent is lowered.
Claim 3
Dependent Claim
46 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein the air-fuel ratio control means operates to release NO x absorbed in the NO x absorbent by making the air-fuel ratio of the exhaust gas flowing into the NO x absorbent rich.
Claim 4
Dependent Claim
50 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein the air-fuel ratio control means operates to release NO x absorbed in the NO x absorbent by making the air-fuel ratio of the exhaust gas flowing into the NO x absorbent substantially the stoichiometric air-fuel ratio.
Claim 5
Dependent Claim
88 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein the air-fuel ratio control means maintains the air-fuel ratio of the exhaust gas flowing into the NO x absorbent lean for a first predetermined time and decreases the oxygen concentration in the exhaust gas flowing into the NO x absorbent for a second predetermined time so as to release the NO x from the NO x absorbent, wherein the first predetermined time is at least 50 times as long as the second predetermined time.
Claim 6
Dependent Claim
41 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein NO x is absorbed into the NO x absorbent when the air-fuel ratio of the exhaust gas flowing into the NO x absorbent is more than 18.0.
Claim 7
Dependent Claim
50 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein the NO x absorbent contains at least one substance selected from alkali metals comprising potassium, sodium, lithium, or cesium, alkali earth metals comprising barium or calcium, rare earth metals comprising lanthanum and yttrium and contains platinum.
Claim 8
Dependent Claim
26 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein the NO x absorbent comprises a composite oxide of barium and copper.
Claim 9
Dependent Claim
73 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein the air-fuel ratio control means controls the air-fuel ratio of an air-fuel mixture formed in an engine combustion chamber so that the absorption of NO x into the NO x absorbent and the release of NO x from the NO x absorbent are controlled by controlling the air-fuel ratio of the air-fuel mixture formed in the engine combustion chamber.
Claim 10
Dependent Claim
74 words
An exhaust purification device of an internal combustion engine according to claim 8, wherein said air-fuel ratio control means makes the air-fuel ratio of the air-fuel mixture formed in the combustion chamber lean when the NO x should be absorbed into the NO x absorbent and makes the air-fuel ratio of the air-fuel mixture formed in the combustion chamber is not lean when the NO x should be released from the NO x absorbent.
Claim 11
Dependent Claim
59 words
An exhaust purification device of an internal combustion engine according to claim 9, wherein the internal combustion engine comprises a gasoline engine and said air-fuel ratio control means controls the absorption of NO x into the NO x absorbent and the releasing of NO x from the NO x absorbent by controlling the fuel amount supplied to the engine.
Claim 12
Dependent Claim
55 words
An exhaust purification device of an internal combustion engine according to claim 10, wherein said air-fuel ratio control means maintains the air-fuel ratio of the air-fuel mixture formed in the combustion chamber at almost a constant lean air-fuel ratio of more than 18.0 when the NO x should be absorbed into the NO x absorbent.
Claim 13
Dependent Claim
59 words
An exhaust purification device of an internal combustion engine according to claim 10, further comprising memory means which stores in advance the amount of fuel determined in accordance with the operation state of the engine, said air-fuel ratio control means determines the amount of fuel supplied to the engine based on the fuel amount stored in said memory means.
Claim 14
Dependent Claim
105 words
An exhaust purification device of an internal combustion engine according to claim 10, further comprising memory means which stores in advance the basic fuel amount determined in accordance with the operation state of the engine and an air-fuel ratio sensor which is provided in the exhaust passage of the engine and detects the air-fuel ratio of the exhaust gas flowing in the exhaust passage, said air-fuel ratio control means corrects the basic fuel amount so that the air-fuel ratio of the exhaust gas becomes the target air-fuel ratio by a feedback correction coefficient varied in accordance with the output signal of said air-fuel ratio sensor.
Claim 15
Dependent Claim
133 words
An exhaust purification device of an internal combustion engine according to claim 13, wherein said air-fuel ratio control means corrects the basic fuel amount so that the air-fuel ratio of the exhaust gas becomes the target air-fuel ratio by the feedback correction coefficient when the NO x should be absorbed into the NO x absorbent and, at the same time, corrects said feedback correction coefficient by a learning coefficient so that said feedback correction coefficient fluctuates around a reference value, and said air-fuel ratio control means fixes the feedback correction value to said reference value when the NO x should be released from the NO x absorbent and, at the same time, determines the amount of fuel to be supplied to the engine based on the learning coefficient and the basic fuel amount.
Claim 16
Dependent Claim
92 words
An exhaust purification device of an internal combustion engine according to claim 9, wherein the internal combustion engine comprises a diesel engine equipped with a fuel injector which injects the fuel into the combustion chamber and a throttle valve disposed in the intake passage of the engine; and said air-fuel ratio control means controls the absorption of NO x into the NO x absorbent and the releasing of NO x from the NO x absorbent by controlling the amount of injection from the fuel injector and the opening degree of throttle valve.
Claim 17
Dependent Claim
42 words
An exhaust purification device of an internal combustion engine according to claim 15, wherein said air-fuel ratio control means increases the injection amount and decreases the throttle valve opening degree when the NO x should be released from the NO x absorbent.
Claim 18
Dependent Claim
93 words
An exhaust purification device of an internal combustion engine according to claim 1, further comprising air-fuel ratio control means which controls the air-fuel ratio of the exhaust gas discharged from the engine combustion chamber and flowing into the NO x absorbent in the exhaust passage of the engine, and the absorption of NO x into the NO x absorbent and the releasing of NO x from the NO x absorbent are controlled by controlling the air-fuel ratio of the exhaust gas flowing into the NO x absorbent by said air-fuel ratio control means.
Claim 19
Dependent Claim
79 words
An exhaust purification device of an internal combustion engine according to claim 17, wherein said air-fuel ratio control means makes the air-fuel ratio of the exhaust gas flowing into the NO x absorbent lean when the NO x should be absorbed into the NO x absorbent, while makes the air-fuel ratio of the exhaust gas flowing into the NO x absorbent the stoichiometric air-fuel ratio or rich when the NO x should be released from the NO x absorbent.
Claim 20
Dependent Claim
45 words
An exhaust purification device of an internal combustion engine according to claim 18, wherein said air-fuel ratio control means supplies a reducing agent to the interior of the exhaust passage of the engine when the NO x should be released from the NO x absorbent.
Claim 21
Dependent Claim
22 words
An exhaust purification device of an internal combustion engine according to claim 19, wherein said reducing agent is made of a hydrocarbon.
Claim 22
Dependent Claim
33 words
An exhaust purification device of an internal combustion engine according to claim 20, wherein said hydrocarbon comprises at least one member selected from gasoline, isoctane, hexane, heptane, butane, propane, light oil, and kerosine.
Claim 23
Dependent Claim
97 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein the air-fuel ratio control means lowers the oxygen concentration in the exhaust gas flowing into the NO x absorbent during a first predetermined set-up period of time so as to release the NO x from the absorbent when a period of time during which the air-fuel ratio of the exhaust gas flowing into the NO x absorbent has previously been made lean and, during which NO x has been absorbed into the NO x absorbent, exceeds a predetermined second set-up period of time.
Claim 24
Dependent Claim
52 words
An exhaust purification device of an internal combustion engine according to claim 22, wherein said NO x releasing control means makes the air-fuel ratio of the exhaust gas flowing into the NO x absorbent the stoichiometric air-fuel ratio or rich when the NO x should be released from the NO x absorbent.
Claim 25
Dependent Claim
76 words
An exhaust purification device of an internal combustion engine according to claim 22, wherein the NO x releasing control means is provided with NO x amount estimation means for estimating the amount of NO x absorbed into the NO x absorbent, and said NO x releasing control means decides that said second set-up period has elapsed when the amount of NO x estimated by the NO x amount estimation means exceeds a preliminarily determined set-up amount.
Claim 26
Dependent Claim
51 words
An exhaust purification device of an internal combustion engine according to claim 24, wherein said NO x amount estimation means decides that the amount of NO x absorbed in the NO x absorbent exceeds said set-up amount when a cumulative value of an engine speed exceeds a preliminarily determined set-up value.
Claim 27
Dependent Claim
59 words
An exhaust purification device of an internal combustion engine according to claim 24, wherein said NO x amount estimation means decides that substantially all of the NO x absorbed in the NO x absorbent has released when the air-fuel ratio of the air-fuel mixture formed in the engine combustion chamber is not lean for a predetermined time or more.
Claim 28
Dependent Claim
24 words
An exhaust purification device of an internal combustion engine according to claim 22, wherein said second set-up period is substantially less than 20 seconds.
Claim 29
Dependent Claim
123 words
An exhaust purification device of an internal combustion engine according to claim 22, wherein said NO x releasing control means is provided with a temperature sensor for detecting a temperature of the exhaust gas flowing into the NO x absorbent, and said NO x releasing control means is provided with prohibition means which prohibits the lowering of the oxygen concentration in the exhaust gas flowing into the NO x absorbent even if the period for which the NO x is absorbed into the NO x absorbent exceeds said first set-up period when the temperature of the exhaust gas flowing into the NO x absorbent becomes lower than a limit temperature at which the NO x can be absorbed by the NO x absorbent.
Claim 30
Dependent Claim
74 words
An exhaust purification device of an internal combustion engine according to claim 28, wherein said NO x releasing control means immediately lowers the oxygen concentration in the exhaust gas flowing into the NO x absorbent when the temperature of the exhaust gas flowing into the NO x absorbent becomes higher than said limit temperature after the oxygen concentration in the exhaust gas flowing into the NO x absorbent is lowered by said prohibition means.
Claim 31
Dependent Claim
39 words
An exhaust purification device of an internal combustion engine according to claim 1, wherein a catalyst which can reduce at least the NO x is disposed in the exhaust passage of the engine downstream of the NO x absorbent.
Claim 32
Dependent Claim
20 words
An exhaust purification device of an internal combustion engine according to claim 30, wherein said catalyst comprises a three-way catalyst.
Claim 33
Dependent Claim
38 words
An exhaust purification device of an internal combustion engine-according to claim 1, wherein a catalyst which can purify the unburnt HC and CO is disposed in the exhaust passage of the engine upstream of the NO x absorbent.
Claim 34
Dependent Claim
20 words
An exhaust purification device of an internal combustion engine according to claim 32, wherein said catalyst comprises a three-way catalyst.
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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) | 1998-12-11 | 1999-06-12 | 1999-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-11 | 2003-06-12 | 2003-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-11 | 2007-06-12 | 2007-12-12 | $7700.00 | Window Closed / Lapsed |