# US 5,706,793 A · Method and system for monitoring fuel delivery of an engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,793 A - Document ID: US5706793A - Status: Granted - Kind: A - Application number: 08/786,131 - Filed: 1997-01-17 - Granted: 1998-01-13 - Earliest claimed: 1997-01-17 - Assignees: Ford Global Technologies, LLC - Inventors: Daniel V. Orzel; David Karl Bidner - Web page: https://patentgrep.com/patent/US5706793A ## CPC - F02D 41/22: Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} - F02D 41/0087: {Selective cylinder activation, i.e. partial cylinder operation (deceleration cut-off F02D41/123)} - 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 A method and system for monitoring fuel delivery to an internal combustion engine having a first and second mode of operation and controlling the engine accordingly. An oxygen content of exhaust gas emitted from the engine is sensed and a corresponding oxygen content signal is generated. Air fuel ratio correction data is determined based on the oxygen content signal. If the engine is operating in the first mode, the air fuel ratio correction data is compared to a first set of predetermined air fuel ratio correction thresholds and a first failure signal is generated based on the comparison between the air fuel ratio correction data and the first set of predetermined air fuel ratio correction thresholds. If the engine is operating in the second mode, the air fuel ratio correction data is compared to a second set of predetermined air fuel ratio correction thresholds and a second failure signal is generated based on the comparison between the air fuel ratio correction data and the second set of predetermined air fuel ratio correction thresholds. The engine is controlled based on the first and second failure signals. ## Claims ### Claim 1 A method for monitoring fuel delivery to an internal combustion engine and controlling the engine accordingly, the engine having a first and second mode of operation and emitting exhaust gas, the method comprising: sensing an oxygen content of the exhaust gas and generating an oxygen content signal; determining air fuel ratio correction data based on the oxygen content signal; if the engine is operating in the first mode, comparing the air fuel ratio correction data to a first set of predetermined air fuel ratio correction thresholds to obtain a first signal; if the engine is operating in the second mode, comparing the air fuel ratio correction data to a second set of predetermined air fuel ratio correction thresholds to obtain a second signal; and controlling the engine based on the first and second signals. ### Claim 2 (depends on 1) The method as recited in claim 1 wherein controlling the engine based on the first signal includes generating a first failure signal based on the comparison between the air fuel ratio correction data and the first set of predetermined air fuel ratio correction thresholds. ### Claim 3 (depends on 2) The method as recited in claim 2 wherein controlling the engine based on the second signal includes generating a second failure signal based on the comparison between the air fuel ratio correction data and the second set of predetermined air fuel ratio correction thresholds. ### Claim 4 (depends on 3) The method as recited in claim 3 further comprising illuminating a display in response to the first or second failure signal. ### Claim 5 (depends on 1) The method as recited in claim 1 further comprising determining if the engine is operating in the first mode or the second mode. ### Claim 6 (depends on 5) The method as recited in claim 5 wherein determining if the engine is operating in the first mode or the second mode includes determining a number of cylinders activated during operation of the engine. ### Claim 7 (depends on 1) The method as recited in claim 1 wherein determining air fuel ratio correction data includes determining a long term air fuel ratio factor and determining a short term air fuel ratio factor. ### Claim 8 (depends on 7) The method as recited in claim 7 wherein comparing the air fuel ratio correction data to the first set of predetermined air fuel ratio correction thresholds comprises: comparing the long term air fuel ratio factor to a set of predetermined minimum long term air fuel ratio correction thresholds; and comparing the long term air fuel ratio factor a set of predetermined maximum long term air fuel ratio correction thresholds. ### Claim 9 (depends on 7) The method as recited in claim 7 wherein comparing the air fuel ratio correction data to the second set of predetermined air fuel ratio correction thresholds comprises: comparing the short term air fuel ratio factor to a set of predetermined minimum short term air fuel ratio correction thresholds; and comparing the short term air fuel ratio factor to a set of predetermined maximum short term air fuel ratio correction thresholds. ### Claim 10 A system for monitoring fuel delivery to an internal combustion engine and controlling the engine accordingly, the engine having a first and second mode of operation and emitting exhaust gas, the system comprising: a sensor for sensing an oxygen content of the exhaust gas and generating a corresponding oxygen content signal; and control logic operative to determine air fuel ratio correction data based on the oxygen content signal, compare the air fuel ratio correction data to a first set of predetermined air fuel ratio correction thresholds to obtain a first signal if the engine is operating in the first mode, compare the air fuel ratio correction data to a second set of predetermined air fuel ratio correction thresholds if the engine is operating in the second mode, and control the engine based on the first and second signals. ### Claim 11 (depends on 10) The system as recited in claim 10 wherein the control logic is further operative to generate a first failure signal based on the comparison between the air fuel ratio correction data and the first set of predetermined air fuel ratio correction thresholds in controlling the engine based on the first signal. ### Claim 12 (depends on 11) The system as recited in claim 11 wherein the control logic is further operative to generate a second failure signal based on the comparison between the air fuel ratio correction data and the second set of predetermined air fuel ratio correction thresholds in controlling the engine based on the second signal. ### Claim 13 (depends on 12) The system as recited in claim 12 further comprising a display for displaying the first or second failure signal. ### Claim 14 (depends on 10) The system as recited in claim 10 wherein the control logic is further operative to determine if the engine is operating in the first mode or the second mode. ### Claim 15 (depends on 14) The system as recited in claim 14 wherein the control logic is further operative to determine a number of cylinders activated during operation of the engine in determining if the engine is operating in the first mode or the second mode. ### Claim 16 (depends on 10) The system as recited in claim 10 wherein the control logic is further operative to determine a long term air fuel ratio factor and determining a short term air fuel ratio factor in determining air fuel ratio correction data. ### Claim 17 (depends on 16) The system as recited in claim 16 wherein the control logic, in comparing the air fuel ratio correction data to the first set of predetermined air fuel ratio correction thresholds, is further operative to compare the long term air fuel ratio factor to a set of predetermined minimum long term air fuel ratio correction thresholds, and compare the long term air fuel ratio factor a set of predetermined maximum long term air fuel ratio correction thresholds. ### Claim 18 (depends on 16) The system as recited in claim 16 wherein the control logic, in comparing the air fuel ratio correction data to the second set of predetermined air fuel ratio correction thresholds, is further operative to compare the short term air fuel ratio factor to a set of predetermined minimum short term air fuel ratio correction thresholds, and compare the short term air fuel ratio factor to a set of predetermined maximum short term air fuel ratio correction thresholds. ### Claim 19 An article of manufacture for use with an engine having a first and second mode of operation and having a sensor positioned in the engine exhaust upstream of a catalytic converter for sensing an oxygen content of the exhaust gas and generating an oxygen content signal, comprising: a computer storage medium having a computer program encoded therein for causing a computer to control the engine, the computer program for determining air fuel correction data based on the oxygen content signal, comparing the air fuel ratio correction data to a first set of predetermined air fuel ratio correction thresholds to obtain a first signal if the engine is operating the first mode, comparing the air fuel ratio correction data to a second set of predetermined air fuel ratio correction thresholds to obtain a second signal if the engine is operating in the second mode, and controlling the engine based on the first and second signals.