# US 7,610,753 B2 · Exhaust gas purification apparatus for internal combustion engine and method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,610,753 B2 - Document ID: US7610753B2 - Status: Granted - Kind: B2 - Application number: 10/332,239 - Filed: 2002-04-17 - Published: 2005-04-07 - Granted: 2009-11-03 - Earliest claimed: 2001-04-19 - Assignees: Nissan Motor Co., Ltd. - Inventors: Yasuhisa Kitahara - Web page: https://patentgrep.com/patent/US7610753B2 ## CPC - F02D 41/0055: {Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus} - F01N 3/023: using means for regenerating the filters, e.g. by burning trapped particles - F01N 3/035: with catalytic reactors - F01N 3/0842: {Nitrogen oxides} - F01N 9/002: {of filter regeneration} - F02D 41/0245: {by increasing temperature of the exhaust gas leaving the engine} - F02D 41/029: {the exhaust gas treating apparatus being a particulate filter} - F02D 41/1439: {characterised by the position of the sensor} - F02D 41/1441: {Plural sensors} - F02D 41/405: {with post injections} - F01N 3/0814: {combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts} - F01N 3/0821: {combined with particulate filter} - F01N 2250/02: filtering and catalytic conversion - F01N 2250/12: absorption or adsorption, and catalytic conversion - F01N 2250/14: absorption or adsorption, and filtering - F01N 2430/085: at least a part of the injection taking place during expansion or exhaust stroke - F01N 2570/04: Sulfur or sulfur oxides - F01N 2570/10: Carbon or carbon oxides - F01N 2570/12: Hydrocarbons - F01N 2570/14: Nitrogen oxides - F02B 29/04: Cooling of air intake supply - F02B 37/00: Engines characterised by provision of pumps driven at least for part of the time by exhaust - F02B 37/24: by using pumps or turbines with adjustable guide vanes - F02D 41/0002: {Controlling intake air} - F02D 2200/0802: Temperature of the exhaust gas treatment apparatus - F02D 2200/0812: Particle filter loading - F02M 26/05: High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor - Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters - Y02T 10/12: Improving ICE efficiencies - Y02T 10/40: Engine management systems - 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) - 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) - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract According to the present invention, there is disposed in an exhaust passage of an internal combustion engine a filter that traps particulate matter In an exhaust gas, and a catalyst with a three-way function is carried on the filter. At the filter regeneration, by controlling such as an injection amount of post injection, an air-fuel ratio of the exhaust gas at an outlet of the filter is controlled to a stoichiometric ratio, and also by controlling such as an intake air throttle valve, an oxygen concentration of the exhaust gas at an inlet of the filter is controlled. Hence, at the filter regeneration, the particulate can be reliably burned and removed, and at the same time, NOx in addition to HC and CO can be purified. ## Claims ### Claim 1 An exhaust gas purification apparatus for an internal combustion engine, comprising: a filter disposed in an exhaust passage and arranged in fluid communication with the internal combustion engine, that traps particulate matter in exhaust gas in the exhaust passage; a three-way catalyst, carried on the filter; and a control unit, wherein the exhaust passage is shaped such that all of the exhaust gas always passes through the filter and the three-way catalyst before exiting from the exhaust passage, and wherein the control unit is configured to simultaneously perform regeneration of the filter to remove accumulated particulate matter and to purify the three-way catalyst, by controlling at least one engine operating parameter related to combustion of the internal combustion engine, such that exhaust gas flowing out of the internal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio. ### Claim 2 (depends on 1) An exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the control unit controls the air-fuel ratio of the exhaust gas at the outlet of the filter by controlling at least one of post injection amount, post injection timing, exhaust gas recirculation, and intake air throttling. ### Claim 3 (depends on 1) An exhaust gas purification apparatus for an internal combustion engine according to claim 1, further comprising: an NOx trap catalyst disposed in the exhaust passage, that traps NOx when the air-fuel ratio of the exhaust gas is lean, and eliminates and purifies the trapped NOx when the air-fuel ratio is the stoichiometric ratio or rich. ### Claim 4 (depends on 1) An exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein, at times other than during regeneration of the filter, the control unit assumes that the air-fuel ratio of the exhaust gas at the outlet of the filter is equivalent to an air-fuel ratio of the exhaust gas inside the filter. ### Claim 5 (depends on 1) An exhaust gas purification apparatus for an internal combustion engine according to claim 1, further comprising a filter temperature detector positioned downstream of the filter, wherein the filter temperature detector is positioned to contact the exhaust gas before the exhaust gas encounters a junction or other components in the exhaust passage. ### Claim 6 (depends on 1) An exhaust gas purification apparatus for an internal combustion engine according to claim 1, further comprising an oxygen concentration sensor positioned downstream of the filter, wherein the oxygen concentration sensor is positioned to contact the exhaust gas before the exhaust gas encounters a junction or other components in the exhaust passage. ### Claim 7 (depends on 1) An exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the control unit further controls an oxygen concentration of the exhaust gas at an inlet of the filter during the regeneration of the filter. ### Claim 8 (depends on 7) An exhaust gas purification apparatus for an internal according to claim 7, wherein the control unit controls the oxygen concentration of the exhaust gas at the inlet of the filter based on an amount of the particulate matter trapped in the filter. ### Claim 9 (depends on 7) An exhaust gas purification apparatus for an internal combustion engine according to claim 7, further comprising: a filter temperature detector that detects a filter temperature, wherein, during the regeneration of the filter, the control unit increases the oxygen concentration of the exhaust gas at the inlet of the filter when the filter temperature is below a predetermined value. ### Claim 10 (depends on 7) An exhaust gas purification apparatus for an internal combustion engine according to claim 7, further comprising: a filter temperature detector that detects a filter temperature, wherein, during the regeneration of the filter, the control unit lowers the oxygen concentration of the exhaust gas at the inlet of the filter when the filter temperature during the regeneration exceeds predetermined value. ### Claim 11 (depends on 7) An exhaust gas purification apparatus for an internal combustion engine according to claim 7, wherein the control unit controls the oxygen concentration of the exhaust gas at the inlet of the filter by at least one of intake throttling, main injection amount, main injection timing, post injection amount, post injection timing, and exhaust gas recirculation. ### Claim 12 An exhaust gas purification apparatus for an intemal combustion engine, comprising: a filter disposed in an exhaust passage arranged in fluid communication with the internal combustion engine, that traps particulate matter in exhaust gas in the exhaust passage; a three-way catalyst, carried on the filter; and control means for simultaneously performing regeneration of the filter to remove accumulated particulate matter and for purifying the three-way catalyst, by controlling at least one engine operating parameter related to combustion of the internal combustion engine, such that exhaust gas flowing out of the internal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio; wherein the exhaust passage is shaped such that all of the exhaust gas always passes through the filter and the three-way catalyst before exiting from the exhaust passage. ### Claim 13 An exhaust gas purification method for an exhaust gas purification apparatus for an internal combustion engine, wherein the exhaust gas purification apparatus comprises: a filter disposed in an exhaust passage arranged in fluid communication with the internal combustion engine, that traps particulate matter in exhaust gas in the exhaust passage, a three-way catalyst carried on the filter, and a control unit, wherein the exhaust passage is shaped such that all of the exhaust gas always passes through the filter and the three-way catalyst before exiting from the exhaust passage, the method comprising: simultaneously performing regeneration of the filter to remove accumulated particulate matter and purification of the three-way catalyst, by controlling at least one engine operating parameter related to combustion of the internal combustion engine, such that exhaust gas flowing out of the intemal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio. ### Claim 14 (depends on 13) A method according to claim 13, further comprising: detecting an exhaust gas pressure at an inlet side of the filter. ### Claim 15 (depends on 13) A method according to claim 13, further comprising: detecting an exhaust gas temperature at an outlet side of the filter. ### Claim 16 (depends on 13) A method according to claim 13, wherein the step of maintaining comprises detecting at least one of an exhaust gas pressure at an inlet side of the filter, an oxygen concentration in the exhaust gas at an outlet side of the filter, and an exhaust gas temperature at an outlet side of the filter, and outputting a command signal from the control unit to (i) a fuel injection valve to control fuel injection quantities and timing, (ii) an opening angle command signal to the intake throttle valve, or (iii) an opening angle command signal to an EGR control valve. ### Claim 17 (depends on 13) A method according to claim 13, wherein the step of maintainihg comprises detecting a temperature of the filter, and lowering the exhaust gas oxygen concentration at the inlet of the filter if the temperature of the filter exceeds a predetermined value. ### Claim 18 (depends on 13) A method according to claim 13, wherein the step of maintaining comprises detecting an oxygen concentration at the filter outlet, and controlling the concentration by sending a command signal from the control unit to change post injection timing, intake throttling, or post injection amount. ### Claim 19 (depends on 13) A method according to claim 13, further comprising: detecting a temperature of the filter, and increasing the oxygen concentration in exhaust gas at the inlet of the filter if the temperature is below a predetermined value. ### Claim 20 (depends on 13) A method according to claim 13, further comprising purifying HG, CO and NOx within the filter. ### Claim 21 (depends on 13) A method according to claim 13, further comprising: detecting an oxygen concentration in the exhaust gas at an outlet side of the filter. ### Claim 22 (depends on 21) A method according to claim 21, wherein the oxygen concentration detection step is performed at a location downstream of the filter before the exhaust gas flowing from the filter encounters a junction or other components in the exhaust passage. ### Claim 23 (depends on 13) A method according to claim 13, further comprising: detecting a temperature of the filter. ### Claim 24 (depends on 23) A method according to claim 23, wherein the temperature detection step is performed at a location downstream of the filter before the exhaust gas flowing from the filter encounters a junction or other components in the exhaust passage. ### Claim 25 A control unit for an exhaust gas purification system, comprising: a sensor input; and a signal output; wherein the control unit is configured to simultaneously perform regeneration of a filter to remove accumulated particulate matter and to purify of a three-way catalyst, by controlling at least one engine operating parameter related to combustion of an internal combustion engine, such that exhaust gas flowing out of the internal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio; wherein the exhaust gas purification system comprises an exhaust passage shaped such that all of the exhaust gas always passes through the filter and the three-way catalyst before exiting from the exhaust passage. ### Claim 26 A control method for an exhaust gas purification system of an internal combustion engine provided with a filter in an exhaust passage thereof and a three-way function catalyst on the filter, comprising: simultaneously performing regeneration of the filter to remove accumulated particulate matter and purification of the three-way catalyst, by controlling at least one engine operating parameter related to combustion of the internal combustion engine, such that exhaust gas flowing out of the internal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio; wherein the exhaust passage is shaped such that all of the exhaust gas always passes through the filter and the three-way function catalyst before exiting from the exhaust passage.