# US 8,788,180 B2 · EGR control system 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 8,788,180 B2 - Document ID: US8788180B2 - Status: Granted - Kind: B2 - Application number: 13/388,835 - Filed: 2009-08-06 - Published: 2012-05-31 - Granted: 2014-07-22 - Earliest claimed: 2009-08-06 - Assignees: Toyota Jidosha Kabushiki Kaisha - Applicants: Yasuyuki Irisawa - Inventors: Yasuyuki Irisawa - Web page: https://patentgrep.com/patent/US8788180B2 ## CPC - F02D 41/0055: {Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus} - F02M 26/44: in which a main EGR passage is branched into multiple passages - F02M 26/49: Detecting, diagnosing or indicating an abnormal function of the EGR system - F02B 2075/125: {Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber} - F02D 13/0215: {changing the valve timing only} - F02D 41/0065: {Specific aspects of external EGR control (constructional details of EGR system F02M26/00)} - F02D 2041/001: {for engines with variable valve actuation} - F02D 2041/227: {Limping Home, i.e. taking specific engine control measures at abnormal conditions} - F02M 26/47: the characteristics being temperatures, pressures or flow rates - F02M 26/50: Arrangements or methods for preventing or reducing deposits, corrosion or wear caused by impurities (arrangement or layout of EGR passages with means for cleaning or treating the recirculated gases F02M26/35; protection of EGR valves from damage F02M26/74) - 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 - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An object of the present invention is to suppress the dispersion of EGR gas amount between cylinders when the stuck open state arises in an EGR valve in an EGR apparatus for an internal combustion engine in which an EGR passage is branched on an intake system side into a plurality of EGR branch pipes, and the respective EGR branch pipes are connected respectively to intake branch pipes provided for the respective cylinders. In the present invention, if the EGR valve is stuck open, the exhaust pressure is reduced in an exhaust system of the internal combustion engine, while suppressing an amount of decrease in a driving force of a vehicle which carries the internal combustion engine within an allowable range. ## Claims ### Claim 1 An EGR control system for an internal combustion engine, wherein: the internal combustion engine comprises: a plurality of cylinders; a plurality of intake branch pipes which are formed by branching an intake passage and which are connected to the plurality of cylinders respectively; and an EGR apparatus which has an EGR passage for making communication between an exhaust system and an intake system of the internal combustion engine and which has an EGR valve for controlling an amount of EGR gas allowed to flow through the EGR passage, wherein: the EGR passage is branched into a plurality of EGR branch pipes on a side of the intake system, the respective EGR branch pipes are connected to the plurality of intake branch pipes respectively; and the EGR valve is arranged on an upstream side along a flow of the EGR gas as compared with a branched portion of the EGR passage, the EGR control system for the internal combustion engine further comprises: stuck open state judging unit which judges whether or not the EGR valve sticks in a valve open state; and exhaust pressure reducing unit which reduces an exhaust pressure in the exhaust system of the internal combustion engine, while suppressing an amount of decrease in a driving force of a vehicle which carries the internal combustion engine within an allowable range, if it is judged by the stuck open state judging unit that the EGR valve sticks in the valve open state. ### Claim 2 (depends on 1) The EGR control system for the internal combustion engine according to claim 1, further comprising: an exhaust variable valve mechanism which controls a valve opening timing of an exhaust valve of the internal combustion engine, wherein: the exhaust pressure reducing unit reduces the exhaust pressure by retarding the valve opening timing of the exhaust valve within a range until arrival at a bottom dead center of an exhaust stroke by the exhaust variable valve mechanism. ### Claim 3 (depends on 2) The EGR control system for the internal combustion engine according to claim 2, wherein: the exhaust variable valve mechanism is such a mechanism that when the valve opening timing of the exhaust valve is changed, a valve closing timing of the exhaust valve is also changed in accordance therewith; the EGR control system for the internal combustion engine further comprises an intake variable valve mechanism which controls a valve opening timing of an intake valve of the internal combustion engine; and the valve opening timing of the intake valve is retarded by the intake variable valve mechanism when the exhaust pressure reducing unit retards the valve opening timing of the exhaust valve by the exhaust variable valve mechanism. ### Claim 4 (depends on 3) The EGR control system for the internal combustion engine according to claim 3, wherein: the intake variable valve mechanism is such a mechanism that when the valve opening timing of the intake valve is changed, a valve closing timing of the intake valve is also changed in accordance therewith; and an amount of retard is decreased if the EGR valve, which sticks in the valve open state, has a small opening degree as compared with if the EGR valve, which sticks in the valve open state, has a large opening degree, when the valve opening timing of the intake valve is retarded by the intake variable valve mechanism. ### Claim 5 (depends on 1) The EGR control system for the internal combustion engine according to claim 1, further comprising: air-fuel ratio control unit which controls an air-fuel ratio of an air-fuel mixture of the internal combustion engine, wherein: the exhaust pressure reducing unit reduces the exhaust pressure by raising the air-fuel ratio of the air-fuel mixture of the internal combustion engine by the air-fuel ratio control unit as compared with a reference air-fuel ratio which is an air-fuel ratio to be provided in a normal state. ### Claim 6 (depends on 5) The EGR control system for the internal combustion engine according to claim 5, wherein the air-fuel ratio is controlled within a low range if the opening degree of the EGR valve which sticks in the valve open state is not more than a first predetermined opening degree and if the opening degree is not less than a second predetermined opening degree which is larger than the first predetermined opening degree, as compared with if the opening degree is larger than the first predetermined opening degree and smaller than the second predetermined opening degree, when the exhaust pressure reducing unit raises the air-fuel ratio of the air-fuel mixture of the internal combustion engine as compared with the reference air-fuel ratio by the air-fuel ratio control unit. ### Claim 7 (depends on 5) The EGR control system for the internal combustion engine according to claim 5, wherein the larger the opening degree is, the higher the air-fuel ratio is, if the opening degree of the EGR valve which sticks in the valve open state is smaller than a predetermined opening degree, while the larger the opening degree is, the lower the air-fuel ratio is, if the opening degree of the EGR valve which sticks in the valve open state is not less than the predetermined opening degree, when the exhaust pressure reducing unit raises the air-fuel ratio of the air-fuel mixture of the internal combustion engine as compared with the reference air-fuel ratio by the air-fuel ratio control unit. ### Claim 8 (depends on 1) The EGR control system for the internal combustion engine according to claim 1, further comprising: an intake variable valve mechanism which controls a valve closing timing of an intake valve of the internal combustion engine; and air-fuel ratio control unit which controls an air-fuel ratio of an air-fuel mixture of the internal combustion engine, wherein: the exhaust pressure reducing unit reduces the exhaust pressure by retarding the valve closing timing of the intake valve by the intake variable valve mechanism, if an opening degree of the EGR valve which sticks in the valve open state is not more than a predetermined opening degree; and the exhaust pressure reducing unit reduces the exhaust pressure by raising the air-fuel ratio of the air-fuel mixture of the internal combustion engine by the air-fuel ratio control unit as compared with a reference air-fuel ratio which is an air-fuel ratio in a normal state, if the opening degree of the EGR valve which sticks in the valve open state is larger than the predetermined opening degree. ### Claim 9 (depends on 8) The EGR control system for the internal combustion engine according to claim 8, wherein: the predetermined opening degree is a first predetermined opening degree; and the air-fuel ratio is lowered if the opening degree of the EGR valve which sticks in the valve open state is not less than a second predetermined opening degree as compared with if the opening degree is smaller than the second predetermined opening degree, when the opening degree of the EGR valve which sticks in the valve open state is larger than the first predetermined opening degree, and the exhaust pressure reducing unit raises the air-fuel ratio of the air-fuel mixture of the internal combustion engine as compared with the reference air-fuel ratio by the air-fuel ratio control unit. ### Claim 10 (depends on 1) The EGR control system for the internal combustion engine according to claim 1, wherein: the vehicle, which carries the internal combustion engine, further includes a motor as a driving source; and the exhaust pressure reducing unit reduces the exhaust pressure by decreasing an intake air amount of the internal combustion engine, and the amount of decrease in the driving force of the vehicle is suppressed within the allowable range by increasing an output of the motor. ### Claim 11 (depends on 1) The EGR control system for the internal combustion engine according to claim 1, wherein: the plurality of cylinders are divided into those which are included in a plurality of cylinder groups; the EGR passage is connected on a side of the exhaust system to the exhaust system which corresponds to only a part of the cylinder group or groups of the plurality of cylinder groups; and the exhaust pressure reducing unit reduces the exhaust pressure in the exhaust system to which the EGR passage is connected, if it is judged by the stuck open state judging unit that the EGR valve sticks in the valve open state.