# US 10,371,029 B2 · Exhaust gas control apparatus 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 10,371,029 B2 - Document ID: US10371029B2 - Status: Granted - Kind: B2 - Application number: 15/827,242 - Filed: 2017-11-30 - Published: 2018-06-14 - Granted: 2019-08-06 - Earliest claimed: 2016-12-09 - Assignees: Toyota Jidasha Kabushiki Kaisha - Applicants: Toyota Jidosha Kabushiki Kaisha - Inventors: Tetsuya Sakuma; Yoshihisa Tsukamoto - Web page: https://patentgrep.com/patent/US10371029B2 ## CPC - F01N 3/2013: {using electric or magnetic heating means} - F01N 3/0814: {combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts} - F01N 3/2066: {Selective catalytic reduction [SCR]} - F01N 9/00: Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) - F01N 11/00: Monitoring or diagnostic devices for exhaust-gas treatment apparatus - F01N 11/002: {the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus} - F01N 13/009: {having two or more separate purifying devices arranged in series} - F01N 2240/16: an electric heater, i.e. a resistance heater - F01N 2260/04: for regeneration or reactivation, e.g. of catalyst - F01N 2550/02: Catalytic activity of catalytic converters - F01N 2550/03: of sorbing activity of adsorbents or absorbents - F01N 2560/06: the means being a temperature sensor - F01N 2570/14: Nitrogen oxides - F01N 2610/02: the substance being ammonia or urea - F01N 2900/1602: Temperature of exhaust gas apparatus - F01N 2900/1621: Catalyst conversion efficiency - Y02T 10/12: Improving ICE efficiencies - Y02T 10/40: Engine management systems - 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) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An exhaust gas control apparatus for an internal combustion engine includes: an SCR catalyst including transition metal ions for reducing NOX in exhaust gas with NH3 as a reducing agent; detection means for detecting temperature of the SCR catalyst; and a heater configured to heat the SCR catalyst. When NOX does not flow into the SCR catalyst, and the temperature detected by the detection means is below a first temperature that is a temperature causing exhibition of valence recovery of transition metal ions, the heater is controlled such that the SCR catalyst is heated up to a first temperature or above and that the SCR catalyst is maintained at or above the first temperature for a prescribed period so as to achieve valence recovery of the transition metal ions put in a deteriorated state. ## Claims ### Claim 1 An exhaust gas control apparatus for an internal combustion engine, the exhaust gas control apparatus comprising: a selective catalytic reduction catalyst disposed in an exhaust passage of the internal combustion engine, the selective catalytic reduction catalyst including transition metal ions for reducing NOX in exhaust gas with NH3 as a reducing agent; a heater configured to heat the selective catalytic reduction catalyst; and an electronic control unit configured to detect temperature of the selective catalytic reduction catalyst, and execute recovery processing when NOX does not flow into the selective catalytic reduction catalyst and the temperature of the selective catalytic reduction catalyst is below a first temperature that is a temperature causing exhibition of valence recovery of the transition metal ions, the recovery processing being processing of controlling the heater so as to heat the selective catalytic reduction catalyst up to the first temperature or above and to maintain the selective catalytic reduction catalyst at or above the first temperature for a prescribed period. ### Claim 2 (depends on 1) The exhaust gas control apparatus according to claim 1, wherein the electronic control unit is configured to execute the recovery processing with shutdown of the internal combustion engine as a trigger. ### Claim 3 (depends on 2) The exhaust gas control apparatus according to claim 2, wherein the electronic control unit is configured to control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to or above the first temperature and below a second temperature, the second temperature being a temperature that causes exhibition of NH3 oxidation. ### Claim 4 (depends on 3) The exhaust gas control apparatus according to claim 3, wherein the electronic control unit is configured to control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to or above the first temperature and below the second temperature, when the temperature of the selective catalytic reduction catalyst upon the shutdown of the internal combustion engine is below a third temperature, and control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to or above the second temperature, when the temperature of the selective catalytic reduction catalyst upon the shutdown of the internal combustion engine is equal to or above the third temperature, and the third temperature is a temperature below the second temperature, the third temperature causing exhibition of NH3 desorption. ### Claim 5 (depends on 1) The exhaust gas control apparatus according to claim 1, wherein the electronic control unit is configured to execute the recovery processing when the temperature of the selective catalytic reduction catalyst is below the first temperature while fuel-cut processing of the internal combustion engine is under execution. ### Claim 6 (depends on 1) The exhaust gas control apparatus according to claim 1, further comprising: a NOX storage reduction catalyst disposed in a portion of the exhaust passage upstream from the selective catalytic reduction catalyst, the NOX storage reduction catalyst being configured to store NOX in the exhaust gas when an air-fuel ratio of the exhaust gas is a lean air-fuel ratio above a stoichiometric air-fuel ratio, and reduce, while emitting, the stored NOX when the air-fuel ratio of the exhaust gas is a rich air-fuel ratio below the stoichiometric air-fuel ratio, wherein the electronic control unit is configured to execute the recovery processing during operation of the internal combustion engine, when the air-fuel ratio of the exhaust gas flowing into the NOX storage reduction catalyst is the lean air-fuel ratio, a NOX storage amount of the NOX storage reduction catalyst is equal to or below a specified upper limit, and the temperature of the selective catalytic reduction catalyst is below the first temperature. ### Claim 7 (depends on 5) The exhaust gas control apparatus according to claim 5, wherein the electronic control unit is configured to control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to or above the first temperature and below a third temperature, the third temperature being a temperature that causes exhibition of NH3 desorption. ### Claim 8 (depends on 6) The exhaust gas control apparatus according to claim 6, wherein the electronic control unit is configured to control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to or above the first temperature and below a third temperature, the third temperature being a temperature that causes exhibition of NH3 desorption. ### Claim 9 (depends on 7) The exhaust gas control apparatus according to claim 7, wherein the electronic control unit is configured to control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to or above the first temperature and below the third temperature, when the temperature of the selective catalytic reduction catalyst upon start of the recovery processing is below the third temperature, and control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to or above a second temperature that is above the third temperature, when the temperature of the selective catalytic reduction catalyst upon start of the recovery processing is equal to or above the third temperature, and the second temperature is a temperature that causes exhibition of NH3 oxidation. ### Claim 10 (depends on 8) The exhaust gas control apparatus according to claim 8, wherein the electronic control unit is configured to control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to above the first temperature and below the third temperature, when the temperature of the selective catalytic reduction catalyst upon start of the recovery processing is below the third temperature, and control the heater such that the temperature of the selective catalytic reduction catalyst during execution of the recovery processing becomes equal to above a second temperature that is above the third temperature, when the temperature of the selective catalytic reduction catalyst upon start of the recovery processing is equal to or above the third temperature, and the second temperature is a temperature that causes exhibition of NH3 oxidation. ### Claim 11 (depends on 5) The exhaust gas control apparatus according to claim 5, wherein the electronic control unit is configured to control the heater such that in a case where an amount of gas flowing through the selective catalytic reduction catalyst during execution of the recovery processing is small, a heating amount of the selective catalytic reduction catalyst heated by the heater decreases as compared with a case where the amount of gas is large. ### Claim 12 (depends on 6) The exhaust gas control apparatus according to claim 6, wherein the electronic control unit is configured to control the heater such that in a case where an amount of gas flowing through the selective catalytic reduction catalyst during execution of the recovery processing is small, a heating amount of the selective catalytic reduction catalyst heated by the heater decreases as compared with a case where the amount of gas is large. ### Claim 13 (depends on 1) The exhaust gas control apparatus according to claim 1, wherein the electronic control unit is configured to estimate a requested recovery amount that is an amount of the transition metal ions that need valence recovery, among the transition metal ions included in the selective catalytic reduction catalyst, and execute the recovery processing such that in a case where the requested recovery amount is small, the prescribed period is shortened as compared in a case where the requested recovery amount is large. ### Claim 14 (depends on 13) The exhaust gas control apparatus according to claim 13, wherein the electronic control unit is configured not to execute the recovery processing when the estimated requested recovery amount is below a specified threshold.