EP0616115A1
Expired / Lapsed
EP
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Exhaust gas purifying apparatus and method for internal combustion engine
Assignee: Hitachi Ltd
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Filing: 1994-03-08
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Granted: —
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Expires: 2014-03-08
Abstract
Abstract An apparatus is provided for purifying an exhaust gas discharged from an internal combustion engine (8), which comprises a first exhaust gas passage including a nitrogen oxide removing catalyst (14) and a three way catalyst (15), a second exhaust gas passage including the three way catalyst, valve means (16) for selectively directing the exhaust gas to the first and second exhaust gas passages, and means (18) for controlling the valve means so as to direct the exhaust gas to the first exhaust gas passage to thereby pass the exhaust gas through the nitrogen oxide removing catalyst and the three way catalyst in the same order when the temperature of the nitrogen oxide removing catalyst is within a hydrocarbon adsorbing range of temperature thereof while the engine is warming up and to the second exhaust gas passage to thereby pass the exhaust gas through the three way catalyst when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range of temperature thereof.
Inventors
- 👤 Osamu Kuroda
- 👤 Takahiro Tachi
- 👤 Miho Saito
- 👤 Toshio Ogawa
- 👤 Noriko Watanabe
- 👤 Akira Kato
- 👤 Hiroshi Miyadera
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 09:01
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/0807; F01N3/0828; F01N3/0835; B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9495; F01N13/00; F01N13/009; F01N3/0871; F01N3/0878; F01N2240/00; F01N2240/18; F01N2250/00; F01N2250/12; F01N2410/00; F01N2410/12; F01N2570/00; F01N2570/14; F01N3/10; F01N3/18; F01N3/20; F02; F02B; F02B1/00; F02B1/02; F02B1/04; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
162 words
An apparatus for purifying an exhaust gas discharged from an internal combustion engine (8), comprising a first exhaust gas passage including a nitrogen oxide removing catalyst (14) and a three way catalyst (15), a second exhaust gas passage including the three way catalyst (15), valve means (16) for selectively directing the exhaust gas to the first and second exhaust gas passages, and means (18) for controlling the valve means so as to direct the exhaust gas to the first exhaust gas passage to thereby pass the exhaust gas through the nitrogen oxide removing catalyst and the three way catalyst in the same order when the temperature of the nitrogen oxide removing catalyst is within a hydrocarbon adsorbing range of temperature thereof while the engine is warming up and to the second exhaust gas passage to thereby pass the exhaust gas through the three way catalyst when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range of temperature thereof.
Claim 2
Dependent Claim
44 words
An apparatus according to claim 1, further comprising means for judging whether or not the engine is warming up after starting and means for judging whether or not the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range of temperature thereof.
Claim 3
Dependent Claim
32 words
An apparatus according to claim 2, wherein the warm-up judging means comprises means (9, 20) for detecting the temperature of either one of cooling water for the engine and the exhaust gas.
Claim 4
Dependent Claim
91 words
An apparatus according to claim 3, further comprising means (11) for detecting an air to fuel ratio of the engine to determine in which region of a rich, lean or stoichiometric region the air to fuel ratio is after completion of the warm-up of the engine, the valve means controlling means controlling the valve means so as to direct the exhaust gas to the second exhaust gas passage in association with the air to fuel ratio detecting means when the air to fuel ratio is in the rich and stoichiometric regions.
Claim 5
Dependent Claim
50 words
An apparatus according to claim 4, wherein the valve means controlling means controls the valve means so as to direct the exhaust gas to the first exhaust gas passage in association with the air to fuel ratio detecting means when the air to fuel ratio is in the lean region.
Claim 6
Dependent Claim
52 words
An apparatus according to claim 5, wherein the valve means controlling means controls the valve means so as to direct the exhaust gas to the second exhaust gas passage when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range of temperature thereof while the engine is warming up.
Claim 7
Dependent Claim
31 words
An apparatus according to claim 6, wherein the valve means controlling means compares the detected temperature of either one of the cooling water and the exhaust gas with a predetermined value.
Claim 8
Dependent Claim
40 words
An apparatus according to claim 7, wherein the nitrogen oxide removing catalyst temperature judging means comprises means (17, 20) for detecting the temperature of either one of the nitrogen oxide removing means and the exhaust gas at an outlet thereof.
Claim 9
Dependent Claim
37 words
An apparatus according to claim 8, wherein the valve means controlling means compares the detected temperature of either one of the nitrogen oxide removing means and the exhaust gas at the outlet thereof with a predetermined value.
Claim 10
Dependent Claim
24 words
An apparatus according to claim 9, wherein the air to fuel ratio detecting means compares the detected air to ratio with a predetermined value.
Claim 11
Dependent Claim
73 words
An apparatus according to claim 1, wherein the second exhaust gas passage constitutes part of a main exhaust gas passage (12) extended from the engine, the main exhaust gas passage has a bypath exhaust gas passage (13) provided upstream from the three way catalyst, and the nitrogen oxide removing catalyst is provided in the bypath exhaust gas passage so as to form the first exhaust gas passage together with the three way catalyst.
Claim 12
Dependent Claim
36 words
An apparatus according to claim 1, wherein the first exhaust gas passage further includes a hydrocarbon adsorbent (22) other than the nitrogen oxide removing catalyst, the hydrocarbon adsorbent being provided upstream from the three way catalyst.
Claim 13
Dependent Claim
91 words
An apparatus according to claim 12, further comprising means (11) for detecting an air to fuel ratio of the engine to determine in which region of a rich, lean or stoichiometric region the air to fuel ratio is after completion of the warm-up of the engine, the valve means controlling means controlling the valve means so as to direct the exhaust gas to the second exhaust gas passage in association with the air to fuel ratio detecting means when the air to fuel ratio is in the rich and stoichiometric regions.
Claim 14
Dependent Claim
77 words
An apparatus according to claim 12, wherein the second exhaust gas passage constitutes part of a main exhaust gas passage (12) extended from the engine, the main exhaust gas passage has a bypath exhaust gas passage (13) provided upstream from the three way catalyst, and the nitrogen oxide removing catalyst and the hydrocarbon adsorbent are provided in the bypath exhaust gas passage so as to form the first exhaust gas passage together with the three way catalyst.
Claim 15
Dependent Claim
24 words
An apparatus according to claim 14, wherein the valve means controlling means is provided at a downstream end of the bypath exhaust gas passage.
Claim 16
Independent Claim
93 words
An apparatus for purifying an exhaust gas discharged from an internal combustion engine (8), comprising a nitrogen oxide removing catalyst (14) through which the exhaust gas is passed, a three way catalyst (15) through which the passed exhaust gas is passed, a bypath exhaust gas passage (13) which is so provided as to penetrate the nitrogen oxide removing catalyst to thereby pass the exhaust gas through the bypath exhaust gas passage and the three way catalyst in the same order, and valve means (16) for opening and closing the bypath exhaust gas passage.
Claim 17
Dependent Claim
19 words
An apparatus according to claim 16, further comprising a hydrocarbon adsorbent (22) which the bypath exhaust gas passage penetrates.
Claim 18
Independent Claim
186 words
A method of purifying an exhaust gas discharged from an internal combustion engine (8) provided with a first exhaust gas passage including a nitrogen oxide removing catalyst (14) and a three way catalyst(15), and a second exhaust gas passage including the three way catalyst, the method comprising the steps of judging whether or not the engine is warming up after starting, judging whether or not the temperature of the nitrogen oxide removing catalyst exceeds a hydrocarbon adsorbing range of temperature thereof, and directing the exhaust gas to first exhaust gas passage to thereby pass the exhaust gas through the nitrogen oxide removing catalyst and the three way catalyst in the same order when the temperature of the nitrogen oxide removing catalyst is within the hydrocarbon adsorbing range of temperature thereof while the engine is warming up and to the second exhaust gas passage to thereby pass the exhaust gas through the three way catalyst when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range of temperature thereof in association with the warm-up judging means and the nitrogen oxide removing temperature judging means.
Claim 19
Dependent Claim
36 words
A method according to claim 18, wherein the first exhaust gas passage further includes a hydrocarbon absorbent (22) other than the nitrogen oxide removing catalyst, the hydrocarbon adsorbent being provided upstream from the three way catalyst.
Claim 20
Dependent Claim
84 words
A method according to claim 18, further comprising the step of detecting an air to fuel ratio of the engine to determine in which region of a rich, lean or stoichiometric region the air to fuel ratio is after completion of the warm-up of the engine, the exhaust gas directing step directing the exhaust gas to the second exhaust gas passage in association with the air to fuel ratio detecting means when the air to fuel ratio is in the rich and stoichiometric regions.
Claim 21
Dependent Claim
43 words
A method according to claim 20, wherein the exhaust gas directing step directs the exhaust gas to the first exhaust gas passage in association with the air to fuel ratio detecting means when the air to fuel ratio is in the lean region.
References Cited (Backward Citations)
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JPH03141816A
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EP0460542A2
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US5051244A
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FR2686375A1
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