# US 9,752,519 B2 · Method of controlling an exhaust recirculation gas system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,519 B2 - Document ID: US9752519B2 - Status: Granted - Kind: B2 - Application number: 14/516,410 - Filed: 2014-10-16 - Published: 2015-04-16 - Granted: 2017-09-05 - Earliest claimed: 2013-10-16 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: Alberto Vassallo; Stefano Pellegrino; Salvatore Sannino - Web page: https://patentgrep.com/patent/US9752519B2 ## CPC - F02D 41/005: {according to engine operating conditions} - F02D 41/0007: {for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12)} - F02D 41/0065: {Specific aspects of external EGR control (constructional details of EGR system F02M26/00)} - F02M 26/02: EGR systems specially adapted for supercharged engines - 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 - F02M 26/06: Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor - F02M 26/14: in relation to the exhaust system - F02D 41/1445: {the characteristics being related to the exhaust flow} - F02D 41/1446: {the characteristics being exhaust temperatures} - F02D 2200/0406: Intake manifold pressure - F02D 2200/0414: Air temperature - F02D 2200/0418: Air humidity - 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) - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A method of controlling an exhaust gas recirculation system of an internal combustion engine is disclosed. The engine includes a compressor, an intake manifold, an after-treatment system, a low pressure EGR system and a high pressure EGR system. The method temporarily adjusts a low pressure EGR ratio, keeping constant a total EGR rate, after verifying at least one among compressor parameters, after-treatment system parameters or intake manifold parameter. ## Claims ### Claim 1 A method of controlling an exhaust gas recirculation system for an internal combustion engine of the type having a high pressure loop coupled between an exhaust manifold and an intake manifold and a low pressure loop coupled between a point downstream from an after-treatment system and the intake manifold, the method comprising: verifying an operating parameter for a compressor surge condition is within a predetermined operating range and controlling an EGR valve to adjust a low pressure EGR ratio within a desired emission stability range while maintaining a constant total EGR rate based on verification of the operating parameter to recirculate exhaust gas from the low pressure loop and the high pressure loop wherein the LP-EGR ratio is computed as follows: LP-EGR ratio=LP-EGR rate/(LP-EGR rate+HP-EGR rate); wherein the total EGR rate is computed as follows: total EGR rate=LP-EGR rate+HP-EGR rate) and wherein LP-EGR rate is a gas flow rate through the low pressure EGR system and HP-EGR rate is a gas flow rate through the high pressure EGR system. ### Claim 2 (depends on 1) The method according to claim 1, wherein said operating parameter comprise at least one of a compressor pressure ratio (Beta_cmp), a compressor inlet humidity (RH_comp_in), and a compressor outlet temperature (T_comp_out). ### Claim 3 (depends on 2) The method according to claim 2, further comprising verifying an after treatment system parameter comprising at least one of an exhaust gas temperature (T_LNT) and an exhaust gas space velocity (SV_LNT). ### Claim 4 (depends on 3) The method according to claim 3, further comprising verifying an intake manifold temperature (T_int_man). ### Claim 5 (depends on 2) The method according to claim 2 further comprising increasing the low pressure EGR ratio (LP-EGR ratio) when the low pressure EGR ratio (LP-EGR ratio) is lower than a maximum low pressure EGR ratio (LP-EGR ratio_max) and the compressor pressure ratio (Beta_cmp) is higher than a maximum compressor pressure ratio (Beta_cmp_max) and the compressor inlet humidity (RH_comp_in) is lower than maximum compressor inlet humidity (RH_max) and the compressor outlet temperature (T_comp_out) is lower than a maximum compressor outlet temperature (T_max). ### Claim 6 (depends on 4) The method according to claim 4 further comprising decreasing the low pressure EGR ratio (LP-EGR ratio) when the low pressure EGR ratio (LP-EGR ratio) is higher than a minimum low pressure EGR ratio (LP-EGR ratio_min) and the exhaust gas space velocity (SV_LNT_opt) is higher than an optimal exhaust gas space velocity (SV_LNT_opt) and the intake manifold temperature (T_int_man) is lower than a maximum intake manifold temperature (T_int_max) and a compressor pressure ratio (Beta_cmp) is lower than a maximum compressor pressure ratio valve (Beta_cmp_max). ### Claim 7 (depends on 4) The method according to claim 4, further comprising increasing the low pressure EGR ratio (LP-EGR ratio) when the low pressure EGR ratio (LP-EGR ratio) is lower than a maximum low pressure EGR ratio (LP-EGR ratio_max), and the exhaust gas temperature (T_LNT) is higher than a maximum exhaust gas temperature (T_LNT_max) and the compressor inlet relative humidity (RH_comp_in) is lower than a maximum compressor inlet relative humidity (RH_max) and the compressor outlet temperature (T_comp_out) is lower than a maximum compressor outlet temperature (T_max). ### Claim 8 (depends on 1) An internal combustion engine comprising a compressor, an intake manifold, an after-treatment system, a low pressure EGR system and a high pressure EGR system, wherein control of said low pressure EGR system and said high pressure EGR system is performed by using a method according to claim 1. ### Claim 9 (depends on 1) A non-transitory computer readable medium comprising a computer-code suitable for performing the method according to claim 1. ### Claim 10 (depends on 9) A computer program product on which the non-transitory computer readable medium according to claim 9 is stored. ### Claim 11 (depends on 9) A control apparatus for an internal combustion engine, comprising an electronic control unit, a data carrier associated to the electronic control unit and a non-transitory computer readable medium according to claim 9 stored in a memory system. ### Claim 12 A method of controlling an exhaust gas recirculation system for an internal combustion engine of the type having a high pressure loop coupled between an exhaust manifold and an intake manifold and a low pressure loop coupled between a point downstream from an after-treatment system and the intake manifold, the method comprising: verifying, in an electronic control unit, operating parameters for a compressor surge condition, the after-treatment device and the intake manifold are within a predetermined operating range; and controlling an EGR valve with the electronic control unit, to adjust a low pressure EGR ratio within a desired emission stability range while maintaining a constant total EGR rate based on verification of the operating parameters to recirculate exhaust gas from the low pressure loop and the high pressure loop wherein the LP-EGR ratio is computed as follows: LP-EGR ratio=LP-EGR rate/(LP-EGR rate+HP-EGR rate); wherein the total EGR rate is computed as follows: total EGR rate=(LP-EGR rate+HP-EGR rate) and wherein LP-EGR rate is a gas flow rate through the low pressure EGR system and HP-EGR rate is a gas flow rate through the high pressure EGR system. ### Claim 13 A exhaust gas recirculation system for an internal combustion engine comprising: an exhaust gas recirculation system including: a high pressure loop configured to be coupled between an exhaust manifold and an intake manifold of an internal combustion engine; a low pressure loop configured to be coupled between a point downstream from an after-treatment device and the intake manifold of the internal combustion engine; and an EGR valve operable to recirculate exhaust gas from a low pressure loop and a high pressure loop an electronic control unit and a computer program product stored in non-transitory computer readable medium having a computer-code operable with the electronic control unit to verify an operating parameter for a compressor surge condition is within a predetermined operating range; and control the EGR valve to adjust a low pressure EGR ratio within a desired emission stability range while maintaining a constant total EGR rate based on verification of the operating parameter to recirculate exhaust gas at a low pressure EGR ratio and at a total EGR rate; wherein the LP-EGR ratio is computed as follows: LP-EGR ratio=LP-EGR rate/(LP-EGR rate+HP-EGR rate); wherein the total EGR rate is computed as follows: total EGR rate=(LP-EGR rate+HP-EGR rate) and wherein LP-EGR rate is a gas flow rate through the low pressure EGR system and HP-EGR rate is a gas flow rate through the high pressure EGR system.