EP0581279A2
Expired / Lapsed
EP
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An exhaust gas purification device for an engine
Assignee: Toyota Motor Corp
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Filing: 1993-07-29
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Granted: —
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Expires: 2013-07-29
Abstract
Abstract An engine comprising an exhaust passage having therein a NOx absorbent which absorbs the NOx when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent is lean and releases the absorbed NOx when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent becomes the stoichiometric air-fuel ratio or rich. A catalyst having an O2 storage function is arranged in the exhaust passage downstream of the NOx absorbent. When NOx is to be released from the NOx absorbent, the air-fuel ratio of the exhaust gas is made rich to an extent such that he amount of unburned HC and CO is excessive beyond an amount necessary to reduce the whole NOx. <IMAGE>
Inventors
- 👤 Satomi c/o Toyota Jidosha K. K. Seto
- 👤 Shinichi C/O Toyota Jidosha K. K. Takeshima
- 👤 Satoshi c/o Toyota Jidosha K. K. Iguchi
- 👤 Toshiaki C/O Toyota Jidosha K. K. Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 13:44
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/22; F01N3/222; F01N13/00; F01N13/009; F01N3/0807; F01N3/0828; F01N3/0842; F01N3/0871; F01N9/00; F02; F02D; F02D41/00; F02D41/02; F02D41/021; F02D41/0235; F02D41/027; F02D41/0275; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F01N2250/00; F01N2250/12; F01N2570/00; F01N2570/16; F01N3/20; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/40
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
197 words
An exhaust gas purification device for an engine having an exhaust passage, said device comprising: an NO x absorbent arranged in the exhaust passage and absorbing NO x when an air-fuel ratio of exhaust gas flowing into the NO x absorbent is lean, said NO x absorbent releasing absorbed NO x when said air-fuel ratio of exhaust gas becomes rich; an air-fuel ratio control means for controlling said air-fuel ratio of exhaust gas to make said air-fuel ratio of exhaust gas lean when NO x is to be absorbed in said NO x absorbent, said air-fuel ratio control means changing over said air-fuel ratio of exhaust gas from a lean air-fuel ratio to a rich air-fuel ratio and increasing a richness of exhaust gas flowing into said NO x absorbent to a predetermined richness in which the exhaust gas flowing into said NO x absorbent contains therein an excessive amount of unburned components relative to an amount necessary to reduce all of the NO x when NO x is to be released from said NO x absorbent; and unburned component oxidizing means for oxidizing the unburned components of the exhaust gas discharged from said NO x absorbent.
Claim 2
Dependent Claim
46 words
An exhaust gas purification device according to claim 1, wherein said unburned component oxidizing means comprises a catalyst arranged in the exhaust passage downstream of said NO x absorbent, and said catalyst has a function of oxidizing the unburned components by oxygen stored in said catalyst.
Claim 3
Dependent Claim
15 words
An exhaust gas purification device according to claim 2, wherein said catalyst contains cerium therein.
Claim 4
Dependent Claim
41 words
An exhaust gas purification device according to claim 1, wherein said unburned component oxidizing means comprises a secondary air supply device for feeding a secondary air into the exhaust passage downstream of said NO x absorbent to oxidize the unburned components.
Claim 5
Dependent Claim
34 words
An exhaust gas purification device according to claim 4, wherein said secondary air supply device feeds the secondary air into the exhaust passage during the time said air-fuel ratio of exhaust gas is rich.
Claim 6
Dependent Claim
44 words
An exhaust gas purification device according to claim 4, wherein an oxidizing catalyst is arranged in the exhaust passage downstream of said NO x absorbent, and said secondary air is fed into the exhaust passage between said NO x absorbent and said oxidizing catalyst.
Claim 7
Dependent Claim
25 words
An exhaust gas purification device according to claim 1, wherein said predetermined richness is increased as a temperature of said NO x absorbent becomes high.
Claim 8
Dependent Claim
44 words
An exhaust gas purification device according to claim 1, wherein said air-fuel ratio control means gradually reduces the richness of the exhaust gas after increasing it to said predetermined richness and then maintain said air-fuel ratio of exhaust gas at the stoichiometric air-fuel ratio.
Claim 9
Dependent Claim
40 words
An exhaust gas purification device according to claim 8, wherein a time during which said air-fuel ratio of exhaust gas is maintained at the stoichiometric air-fuel ratio is made shorter as a temperature of said NO x absorbent becomes high.
Claim 10
Dependent Claim
34 words
An exhaust gas purificaTIon device according to claim 1, wherein said air-fuel ratio control means controls said air-fuel ratio of exhaust gas by controlling an air-fuel ratio of air-fuel mixture fed into the engine.
Claim 11
Dependent Claim
44 words
An exhaust gas purification device according to claim 1, wherein said NO x absorbent contains at least one substance selected from alkali metals comprising potassium, sodium, lithium, cesium; alkali earth metals comprising barium, calcium; and rare earth metals comprising lanthanum, yttrium and contains platinum.
References Cited (Backward Citations)
No citation records indexed.
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