# US 2014/0190149 A1 · Air-fuel ratio control apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190149 A1 - Document ID: US20140190149A1 - Status: Published application - Kind: A1 - Application number: 14/149,178 - Filed: 2014-01-07 - Published: 2014-07-10 - Earliest claimed: 2013-01-09 - Assignees: Ngk Spark Plug Co., Ltd. - Applicants: NGK Spark Plug Co., Ltd. - Inventors: Kenichiro UMEMOTO; Shuichi HANAI; Koji NAGURA - Web page: https://patentgrep.com/patent/US20140190149A1 ## CPC - F01N 3/20: specially adapted for catalytic conversion (F01N3/22 takes precedence) - F01N 11/007: {the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus} - F02D 41/064: {at cold start (F02D41/067 takes precedence)} - F02D 41/1441: {Plural sensors} - F02D 41/1454: {the characteristics being an oxygen content or concentration or the air-fuel ratio} - F02D 41/1494: {Control of sensor heater} - F01N 2550/02: Catalytic activity of catalytic converters - F01N 2560/025: for measuring or detecting O2, e.g. lambda sensors - F01N 2560/14: having more than one sensor of one kind - F01N 2560/20: Sensor having heating means - 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) - 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) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract When an internal combustion engine (1) is determined to be in a low-temperature start state (an affirmative determination is made in S120), an air-fuel ratio control apparatus (10) controls the temperature of a downstream detection element (17) of a downstream gas sensor (15) to a downstream target temperature by driving a downstream heater (16) of the downstream gas sensor (15) (S170), and feedback-controls the air-fuel ratio of exhaust gas based on the output of the downstream gas sensor (15) (S190). When the engine (1) is determined not to be in the low-temperature start state (a negative determination is made in S120), the air-fuel ratio control apparatus (10) drives an upstream heater (25) of an upstream gas sensor (22) and feedback-controls the air-fuel ratio of exhaust gas based on the output of the upstream gas sensor (22) (S270). ## Claims ### Claim 1 An air-fuel ratio control apparatus comprising: a catalyst provided in an exhaust passage of an internal combustion engine; an upstream gas sensor which is provided in the exhaust passage to be located on the upstream side of the catalyst and which includes a detection element and an element heating heater; a downstream gas sensor which is provided in the exhaust passage to be located on the downstream side of the catalyst and which includes a detection element and an element heating heater; heater control means for controlling the heating states of the element heating heater of the upstream gas sensor and the element heating heater of the downstream gas sensor; and air-fuel ratio control means for controlling exhaust air-fuel ratio on the basis of an output from at least one of the upstream gas sensor and the downstream gas sensor, the air-fuel ratio control apparatus further comprising: start state determination means for determining whether or not the internal combustion engine is in a low-temperature start state, wherein the heater control means controls the temperature of the detection element of the downstream gas sensor to a predetermined downstream target temperature using the element heating heater of the downstream gas sensor when the start state determination means determines that the engine is in the low-temperature start state, and the heater control means controls the temperature of the detection element of the upstream gas sensor to a predetermined upstream target temperature using the element heating heater of the upstream gas sensor when the start state determination means determines that the engine is not in the low-temperature start state; the air-fuel ratio control means feedback-controls the exhaust air-fuel ratio based on the output of the downstream gas sensor when the start state determination means determines that the engine is in the low-temperature start state and the detection element of the downstream gas sensor becomes active, and the air-fuel ratio control means feedback-controls the exhaust air-fuel ratio based on the output of the upstream gas sensor when the start state determination means determines that the engine is not in the low-temperature start state and the detection element of the upstream gas sensor becomes active; and the downstream target temperature is a temperature which is lower than the upstream target temperature and at which the detection element of the downstream gas sensor becomes active, and at which the detection element of the downstream gas sensor does not break due to water adhesion. ### Claim 2 (depends on 1) The air-fuel ratio control apparatus as claimed in claim 1, further comprising catalyst deterioration determination means for determining whether or not a change period of the output of the downstream gas sensor satisfies a predetermined catalyst deterioration condition when the exhaust air-fuel ratio is controlled by the air-fuel ratio control means based on the output of the downstream gas sensor, the catalyst deterioration determination means determining that the catalyst is in a deteriorated state when the change period satisfies the catalyst deterioration condition, and determining that the catalyst is in an undeteriorated state when the change period does not satisfy the catalyst deterioration condition. ### Claim 3 (depends on 1) The air-fuel ratio control apparatus as claimed in claim 1, wherein the detection element of the upstream gas sensor is a plate-shaped oxygen detection element whose output changes linearly in accordance with the oxygen concentration of exhaust gas; and the detection element of the downstream gas sensor is an oxygen detection element which has a bottomed tubular shape and whose output changes abruptly near the theoretical air-fuel ratio.