# US 2021/0340928 A1 · Method of Controlling an Engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0340928 A1 - Document ID: US20210340928A1 - Status: Published application - Kind: A1 - Application number: 17/286,183 - Filed: 2019-10-15 - Published: 2021-11-04 - Earliest claimed: 2018-10-17 - Assignees: Perkins Engines Company Limited - Applicants: Perkins Engines Company Limited - Inventors: Adam Stubbs; Kane Lok; Chris Burgess - Web page: https://patentgrep.com/patent/US20210340928A1 ## 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 41/062: {for starting (F02D41/061 takes precedence)} - F02D 41/1454: {the characteristics being an oxygen content or concentration or the air-fuel ratio} - F02D 41/2403: {using essentially up/down counters} - F02D 2200/60: said parameters being related to the driver demands or status - F02D 2200/606: Driving style, e.g. sporty or economic driving - Y02T 10/12: Improving ICE efficiencies - 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 This disclosure relates to a method of controlling an engine and more particularly for controlling the transition between operating modes of an internal combustion engine such as between an economy mode and a performance mode. The method comprising the steps of determining a current fuel-air ratio at which the engine is operating and comparing it with a predetermined fuel-air ratio limit. The time duration for which the current fuel air-ratio is below the fuel-air ratio limit is determined and compared with a predetermined waiting time threshold value. A count is triggered, which is based on a difference between the current fuel-air ratio and the fuel-air ratio limit when the engine is operating at a current fuel-air ratio which is below the fuel-air ratio limit and this is compared with an intensity threshold value. The operating mode is shifted from the performance mode to the economy mode when both the time duration and the count exceed the waiting time threshold value and the intensity threshold value respectively. The operating mode is automatically shifted back to the performance mode when the current fuel-air ratio reaches or exceeds the fuel ratio limit. The method alternatively comprises using the air-fuel ratio, instead of the fuel-air ratio, and the switch from performance mode to economy mode only occurs when the current air-fuel is above a predetermined air-fuel limit and it remains above the predetermined air-fuel limit until two other predetermined thresholds have been reached. ## Claims ### Claim 1 A method for automatically shifting an operating mode of an internal combustion engine between an economy mode and a performance mode comprising the steps of: determining a current fuel-air ratio at which the engine is operating; comparing the current fuel-air ratio to a predetermined fuel-air ratio limit; determining a time duration for which the current fuel-air ratio is below the fuel-air ratio limit and comparing the time duration to a predetermined waiting time threshold value; providing a count based on a difference between the current fuel-air ratio and the fuel-air ratio limit when the engine is operating at a current fuel-air ratio which is below the fuel-air ratio limit and comparing the count with an intensity threshold value; shifting the operating mode of the engine from the performance mode to the economy mode when both the time duration and the count exceed the waiting time threshold value and the intensity threshold value respectively; and shifting the operating mode of the engine from the economy mode to the performance mode when the current fuel-air ratio reaches or exceeds the fuel-air ratio limit. ### Claim 2 A method for automatically shifting an operating mode of an internal combustion engine between an economy mode and a performance mode comprising the steps of: determining a current air-fuel ratio at which the engine is operating; comparing the current air-fuel ratio to a predetermined air-fuel ratio limit; determining a time duration for which the current air-fuel ratio is above the air-fuel ratio limit and comparing the time duration to a predetermined waiting time threshold value; providing a count based on a difference between the current air-fuel ratio and the air-fuel ratio limit when the engine is operating at a current air-fuel ratio which is above the air-fuel ratio limit and comparing the count with an intensity threshold value; shifting the operating mode of the engine from the performance mode to the economy mode when both the time duration and the count exceed the waiting time threshold value and the intensity threshold value respectively; and shifting the operating mode of the engine from the economy mode to the performance mode when the current fuel-air ratio reaches or falls below the air-fuel ratio limit. ### Claim 3 (depends on 1) A method as claimed in claim 1 in which the time duration and the count are reset to zero when the operating mode of the engine is shifted from the economy mode to the performance mode. ### Claim 4 (depends on 1) A method as claimed in claim 1 in which the time duration and count are set to zero when the engine is started and the shift from the performance mode to the economy mode is prohibited until the engine has satisfied predetermined start-up condition checks. ### Claim 5 (depends on 1) A method as claimed in claim 1 wherein the step of providing the count comprises determining the difference repeatedly such that the count is cumulative. ### Claim 6 (depends on 5) A method as claimed in claim 5 wherein determining the difference repeatedly is performed at a consistent predetermined time interval. ### Claim 7 (depends on 1) A method as claimed in claim 1 further comprising performing start-up condition checks and, in the event that a start-up condition check fails, maintaining the operating mode of the engine in the performance mode. ### Claim 8 (depends on 1) An engine system comprising: an internal combustion engine having at least two operating modes comprising an economy mode and a performance mode; at least one sensor providing at least one output signal according to at least one operating parameter of the engine; and a controller configured to receive said at least one output signal from the at least one sensor and to determine the current fuel-air ratio of the engine from said at least one output signal; wherein a predetermined fuel-air ratio limit, a predetermined waiting time threshold and a predetermined intensity threshold are stored in the controller and the controller is programmed to shift the operating mode of the engine between the economy mode and the performance mode according to the method of claim 1. ### Claim 9 (depends on 8) An engine system according to claim 8 wherein the at least one sensor comprises a fuel-air ratio sensor configured to provide the fuel-air ratio of the engine. ### Claim 10 (depends on 2) An engine system comprising: an internal combustion engine having at least two operating modes comprising an economy mode and a performance mode; at least one sensor providing at least one output signal according to at least one operating parameter of the engine; and a controller configured to receive said at least one output signal from the at least one sensor and to determine the current air-fuel ratio of the engine from said at least one output signal; wherein a predetermined air-fuel ratio limit, a predetermined waiting time threshold and a predetermined intensity threshold are stored in the controller and the controller is programmed to shift the operating mode of the engine between the economy mode and the performance mode according to the method of claim 2. ### Claim 11 (depends on 10) An engine system according to claim 10 wherein the at least one sensor comprises an air-fuel ratio sensor configured to provide the air-fuel ratio of the engine. ### Claim 12 (depends on 8) An engine system according to claim 8 wherein the at least one sensor comprises an oxygen sensor, wherein the operating parameter of the engine comprises a measure of oxygen within the engine. ### Claim 13 (depends on 8) An engine system according to claim 8 further comprising an engine control unit. ### Claim 14 (depends on 13) An engine system according to claim 13 wherein the engine control unit comprises the controller.