# US 2008/0184701 A1 · Exhaust Gas Purifying Device for Internal Combustion Engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0184701 A1 - Document ID: US20080184701A1 - Status: Published application - Kind: A1 - Application number: 11/794,199 - Filed: 2006-05-01 - Published: 2008-08-07 - Earliest claimed: 2005-05-19 - Assignees: Toyota Jidosha Kabushiki Kaisha - Inventors: Kenji Katoh; Shigemasa Hirooka - Web page: https://patentgrep.com/patent/US20080184701A1 ## CPC - F01N 3/0814: {combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts} - F01N 3/2073: {Means for generating a reducing substance from the exhaust gases} - F01N 13/009: {having two or more separate purifying devices arranged in series} - F01N 13/0093: {the purifying devices are of the same type} - F01N 13/0097: {the purifying devices are arranged in a single housing} - F01N 13/011: {having two or more purifying devices arranged in parallel} - F02D 41/0275: {the exhaust gas treating apparatus being a NOx trap or adsorbent} - F01N 2240/30: a fuel reformer - F01N 2560/02: the means being an exhaust gas sensor - F01N 2560/024: for measuring or detecting hydrogen H2 - F01N 2560/026: for measuring or detecting NOx - F02D 2041/147: {the characteristics being a hydrogen content or concentration of the exhaust gases} - F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16) - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) ## Abstract An NOX occluding and reducing catalyst 7 is arranged in an exhaust gas passage 2 of an engine 1 so as to occlude, reduce and purify NOX contained in an exhaust gas. An H2 sensor 33 is arranged in the exhaust gas passage on a downstream side of the NOX occluding and reducing catalyst 7 and a hydrogen component concentration of the exhaust gas is detected. When an amount of NOX occluded in the NOX occluding and reducing catalyst is increased to a predetermined value, an electronic control unit (ECU) 30 of the engine operates the engine at a rich air-fuel ratio, and a regenerating operation, by which a rich air-fuel ratio exhaust gas is supplied to the NOX occluding and reducing catalyst, is executed so as to reduce and purify NOX which is occluded in the NOX occluding and reducing catalyst. At the time of executing the regenerating operation, when the H2 sensor 33 detects hydrogen components in the exhaust gas, ECU 30 finishes the regenerating operation. Due to the foregoing, it is possible to accurately judge the time for terminating the regenerating operation of the NOX occluding and reducing catalyst. ## Claims ### Claim 1 An exhaust gas purifying device for an internal combustion engine comprising: an NOX occluding and reducing catalyst disposed in an exhaust passage of an internal combustion engine, the NOX occluding and reducing catalyst occluding NOX contained in exhaust gas by one of the absorption and the adsorption or by both the absorption and the adsorption when an air-fuel ratio of the exhaust gas flowing into the catalyst is lean, and reducing and purifying the occluded NOX with a reducing component contained in the exhaust gas when an air-fuel ratio of the exhaust gas is a stoichiometric air-fuel ratio or a rich air-fuel ratio; and an H2 sensor disposed in at least one of the exhaust gas passages on the inlet side and the outlet side of the NOX occluding and reducing catalyst for detecting a hydrogen component concentration of the exhaust gas, wherein the exhaust gas purifying device executes a regenerating operation in which the exhaust gas of a rich air-fuel ratio or a stoichiometric air-fuel ratio is supplied to the NOX occluding and reducing catalyst for a predetermined period of time when the NOX occluding and reducing catalyst is to reduce and purify the NOX occluded in the NOX occluding and reducing catalyst and, during the regenerating operation, the exhaust gas purifying device controls the air-fuel ratio of the exhaust gas flowing into the NOX occluding and reducing catalyst based on the hydrogen component concentration, in the exhaust gas, detected by the H2 sensor. ### Claim 2 (depends on 1) An exhaust gas purifying device for an internal combustion engine according to claim 1, wherein the H2 sensor is arranged in an exhaust gas passage on an outlet side of the NOX occluding and reducing catalyst, and at the time of executing the regenerating operation, a time for terminating the regenerating operation is judged according to a hydrogen component concentration in the exhaust gas detected by the outlet side H2 sensor. ### Claim 3 (depends on 1) An exhaust gas purifying device for an internal combustion engine according to claim 1, wherein the H2 sensor is arranged in at least an exhaust gas passage on the outlet side of the NOX occluding and reducing catalyst, the regenerating operation includes operations for first supplying the exhaust gas of a rich air-fuel ratio to the NOX occluding and reducing catalyst and then supplying the exhaust gas of a stoichiometric air-fuel ratio to the NOX occluding and reducing catalyst and, the time at which the exhaust gas air-fuel ratio is switched from the rich air-fuel ratio to the stoichiometric air-fuel ratio is determined in accordance with the hydrogen component concentration detected by the outlet side H2 sensor. ### Claim 4 (depends on 1) An exhaust gas purifying device for an internal combustion engine according to claim 1, wherein the H2 sensor is arranged in an exhaust gas passage on the inlet side of the NOX occluding and reducing catalyst, and at the time of executing the regenerating operation, an air-fuel ratio of the exhaust gas flowing into the NOX occluding and reducing catalyst is controlled so that a hydrogen component concentration in the exhaust gas detected by the inlet side H2 sensor can be a predetermined target value. ### Claim 5 (depends on 4) An exhaust gas purifying device for an internal combustion engine according to claim 4, wherein the target value of the hydrogen component concentration is high at the time of starting the regenerating operation, and then the target value of the hydrogen component concentration is gradually decreased with the lapse of time. ### Claim 6 (depends on 2) An exhaust gas purifying device for an internal combustion engine according to claim 2, wherein according to the lapse of time from the start of the regenerating operation to the end of the regenerating operation which is judged according to the hydrogen component concentration in the exhaust gas detected by the downstream side H2 sensor, a degree of deterioration of the NOX occluding and reducing catalyst is judged. ### Claim 7 An exhaust gas purifying device for an internal combustion engine comprising an NOX occluding and reducing catalyst disposed in an exhaust passage of an internal combustion engine, the NOX occluding and reducing catalyst occluding NOX contained in exhaust gas by one of the absorption and the adsorption or by both the absorption and the adsorption when an air-fuel ratio of the exhaust gas flowing into the catalyst is lean and reducing and purifying the occluded NOX with a reducing component contained in the exhaust gas when an air-fuel ratio of the exhaust gas is a stoichiometric air-fuel ratio or a rich air-fuel ratio, the exhaust gas purifying device for an internal combustion engine further comprising: NOX occluding and reducing catalysts arranged in series to each other on the upstream side and the downstream side of the exhaust gas passage of the internal combustion engine; and an H2 sensor, which is arranged in series to each other in the exhaust gas passage between the upstream side NOX occluding and reducing catalyst and the downstream side NOX occluding and reducing catalyst, for detecting a hydrogen component concentration in the exhaust gas, wherein when the NOX occluding and reducing catalyst is to reduce and purify NOX occluded during a lean air-fuel ratio operation of the engine, at the time of executing a regenerating operation in which the exhaust gas of a rich air-fuel ratio or a stoichiometric air-fuel ratio is supplied to the NOX occluding and reducing catalyst for a predetermined period of time, according to the hydrogen component concentration in the exhaust gas detected by the H2 sensor, an air-fuel ratio of the exhaust gas flowing into the upstream side NOX occluding and reducing catalyst is controlled. ### Claim 8 (depends on 7) An exhaust gas purifying device for an internal combustion engine according to claim 7, wherein an NOX occlusion capacity of the upstream side NOX occluding and reducing catalyst is larger than that of the downstream side NOX occluding and reducing catalyst, an O2 storage capacity of the upstream side NOX occluding and reducing catalyst is smaller than that of the downstream side NOX occluding and reducing catalyst, and an amount of platinum components carried on the upstream side NOX occluding and reducing catalyst is larger than that carried on the downstream side NOX occluding and reducing catalyst. ### Claim 9 (depends on 7, 8) An exhaust gas purifying device for an internal combustion engine according to claim 7 or 8, wherein a time for terminating the regenerating operation is judged according to the hydrogen component concentration in the exhaust gas detected by the H2 sensor at the time of executing the regenerating operation. ### Claim 10 (depends on 7, 8) An exhaust gas purifying device for an internal combustion engine according to claim 7 or 8, wherein the device further executes a poisoning regeneration treatment in order to desorb sulfur oxide occluded in the NOX occluding and reducing catalyst together with NOX from the NOX occluding and reducing catalyst by making the air-fuel ratio of the exhaust gas flowing into the NOX occluding and reducing catalyst to be a rich air-fuel ratio and, at the same time, raising the temperature thereof and, wherein an air-fuel ratio of the exhaust gas flowing into the upstream side NOX occluding and reducing catalyst is controlled according to the hydrogen component concentration in the exhaust gas detected by the H2 sensor in the process of executing the poisoning regeneration treatment. ### Claim 11 (depends on 10) An exhaust gas purifying device for an internal combustion engine, according to claim 10, wherein a time for terminating the poisoning regeneration treatment is judged according to the hydrogen component concentration in the exhaust gas detected by the H2 sensor at the time of executing the poisoning regeneration treatment. ### Claim 12 (depends on 8) An exhaust gas purifying device for an internal combustion engine according to claim 8, wherein a degree of deterioration of the upstream side NOX occluding and reducing catalyst is judged according to a period of time from the start of the regenerating operation to the end of the regenerating operation which is judged according to the hydrogen component concentration, in the exhaust gas, detected by the H2 sensor.