# US 8,543,316 B2 · Air fuel ratio control device of engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,543,316 B2 - Document ID: US8543316B2 - Status: Granted - Kind: B2 - Application number: 13/064,666 - Filed: 2011-04-07 - Published: 2011-10-20 - Granted: 2013-09-24 - Earliest claimed: 2010-04-16 - Assignees: Nikki Co., Ltd. - Applicants: Buso Takigawa; Umerujan Sawut; Tohti Gheyret - Inventors: Buso Takigawa; Umerujan Sawut; Tohti Gheyret - Web page: https://patentgrep.com/patent/US8543316B2 ## CPC - F02D 41/1446: {the characteristics being exhaust temperatures} - F02D 41/1458: {with determination means using an estimation} - 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 air-fuel ratio control device comprising a fuel supply unit, engine operation state detector, air-fuel ratio information detector, and an electronic control unit is disclosed. The electronic control unit determines a fuel injection amount which realizes a target air-fuel ratio while using engine load information by the engine operation state detector on the basis of air-fuel ratio information by the air-fuel ratio information detector, and then outputs a driving signal to the fuel supply unit, to execute feedback control mainly at an excessively rich side air-fuel ratio, characterized in that the air-fuel ratio information detector is an exhaust gas temperature sensor. ## Claims ### Claim 1 An air-fuel ratio control device comprising: fuel supply means; engine operation state detection means; air-fuel ratio information detection means; and an electronic control unit, the electronic control unit being configured to determine a fuel injection amount which realizes a target air-fuel ratio while using engine load information by the engine operation state detection means on the basis of air-fuel ratio information by the air-fuel ratio information detection means, and then output a driving signal to the fuel supply means, to execute feedback control mainly at an excessively rich side air-fuel ratio, wherein the air-fuel ratio information detection means is an exhaust gas temperature sensor, and while estimating an air-fuel ratio at this time on the basis of detected exhaust gas temperature information by a predetermined obtaining method, the air-fuel ratio is used for the control. ### Claim 2 (depends on 1) The air-fuel ratio control device according to claim 1, wherein the air-fuel ratio is obtained on the basis of the exhaust gas temperature information by use of a map or a formula beforehand obtained on the basis of the result of acquired information on an exhaust gas temperature and the air-fuel ratio at this time in a plurality of engine operation states with respect to a target engine, beforehand stored in storage means of the electronic control unit, and indicating a relation between the exhaust gas temperature and the air-fuel ratio. ### Claim 3 (depends on 2) The air-fuel ratio control device according to claim 2, wherein for the feedback control, the exhaust gas temperature during an operation at the target air-fuel ratio is estimated and calculated by two-dimensional interpolation or a polynomial approximate formula to obtain a target temperature, on the basis of engine rotation number information and a plurality of pieces of engine load information, and the feedback control is executed while regulating a fuel supply amount so that the exhaust gas temperature converges to the target temperature. ### Claim 4 (depends on 3) The air-fuel ratio control device according to claim 3, further comprising: engine temperature detection means, wherein an engine warm-up level is estimated and calculated on the basis of detected engine temperature information by one-dimensional interpolation or a polynomial approximate formula, and is add to or subtracted from the calculated target temperature, to correct the target temperature. ### Claim 5 (depends on 3) The air-fuel ratio control device according to claim 3, which calculates the exhaust gas temperature varying with the target air-fuel ratio by one-dimensional interpolation or a polynomial approximate formula, and adds or subtracts the exhaust gas temperature to or from the calculated target temperature, to correct the target temperature. ### Claim 6 (depends on 3) The air-fuel ratio control device according to claim 3, which subjects the calculated target temperature to response delay processing identified with a primary delay plus dead time system, by use of a time constant calculated on the basis of the engine rotation number information and the engine load information by two-dimensional interpolation or a polynomial approximate formula. ### Claim 7 (depends on 3) The air-fuel ratio control device according to claim 3, which judges that the engine is being warmed up to stop the execution of the feedback control, in a case where the calculated target temperature is lower than a predetermined temperature. ### Claim 8 (depends on 3) The air-fuel ratio control device according to claim 3, which judges that the engine causes an accidental fire to stop the execution of the feedback control, in a case where in the detected engine rotation number information, a rotation fluctuation is larger than a predetermined reference. ### Claim 9 (depends on 3) The air-fuel ratio control device according to claim 3, wherein the fuel supply means is an electronic control carburetor including an actuator operating type fuel flow ratio regulating section operated by the electronic control unit. ### Claim 10 (depends on 2) The air-fuel ratio control device according to claim 2, wherein the fuel supply means is an electronic control carburetor including an actuator operating type fuel flow ratio regulating section operated by the electronic control unit. ### Claim 11 (depends on 1) The air-fuel ratio control device according to claim 1, wherein for the feedback control, the exhaust gas temperature during an operation at the target air-fuel ratio is estimated and calculated by two-dimensional interpolation or a polynomial approximate formula to obtain a target temperature, on the basis of engine rotation number information and a plurality of pieces of engine load information, and the feedback control is executed while regulating a fuel supply amount so that the exhaust gas temperature converges to the target temperature. ### Claim 12 (depends on 11) The air-fuel ratio control device according to claim 11, further comprising: engine temperature detection means, wherein an engine warm-up level is estimated and calculated on the basis of detected engine temperature information by one-dimensional interpolation or a polynomial approximate formula, and is add to or subtracted from the calculated target temperature, to correct the target temperature. ### Claim 13 (depends on 11) The air-fuel ratio control device according to claim 11, which calculates the exhaust gas temperature varying with the target air-fuel ratio by one-dimensional interpolation or a polynomial approximate formula, and adds or subtracts the exhaust gas temperature to or from the calculated target temperature, to correct the target temperature. ### Claim 14 (depends on 11) The air-fuel ratio control device according to claim 11, which subjects the calculated target temperature to response delay processing identified with a primary delay plus dead time system, by use of a time constant calculated on the basis of the engine rotation number information and the engine load information by two-dimensional interpolation or a polynomial approximate formula. ### Claim 15 (depends on 11) The air-fuel ratio control device according to claim 11, which judges that the engine is being warmed up to stop the execution of the feedback control, in a case where the calculated target temperature is lower than a predetermined temperature. ### Claim 16 (depends on 11) The air-fuel ratio control device according to claim 11, which judges that the engine causes an accidental fire to stop the execution of the feedback control, in a case where in the detected engine rotation number information, a rotation fluctuation is larger than a predetermined reference. ### Claim 17 (depends on 11) The air-fuel ratio control device according to claim 11, wherein the fuel supply means is an electronic control carburetor including an actuator operating type fuel flow ratio regulating section operated by the electronic control unit. ### Claim 18 (depends on 1) The air-fuel ratio control device according to claim 1, wherein the fuel supply means is an electronic control carburetor including an actuator operating type fuel flow ratio regulating section operated by the electronic control unit.