# US 10,871,140 B1 · Systems and methods for reducing engine torque utilizing split lambda fueling > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,140 B1 - Document ID: US10871140B1 - Status: Granted - Kind: B1 - Application number: 16/657,823 - Filed: 2019-10-18 - Granted: 2020-12-22 - Earliest claimed: 2019-10-18 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Michael Scott Christensen; Aakash Puntambekar; Douglas Raymond Martin; Adam Joseph Krach; John Eric Rollinger - Web page: https://patentgrep.com/patent/US10871140B1 ## CPC - F02P 5/045: {combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02)} - F02P 5/1504: {with particular means during a transient phase, e.g. acceleration, deceleration, gear change (during starting F02P5/1506)} - F02D 37/02: one of the functions being ignition - F02D 41/0082: {per groups or banks (F02D41/0087 takes precedence)} - F02D 41/1446: {the characteristics being exhaust temperatures} - F02P 5/1512: {with particular means concerning an individual cylinder} - F02D 41/021: {Introducing corrections for particular conditions exterior to the engine (conjoint control of vehicle sub-units for propelling the vehicle B60W30/18)} - F02D 41/023: {in relation with the gear ratio shifting (conjoint control for improving gear change B60W30/19)} - F02D 2250/21: during a transition between engine operation modes or states - Y02T 10/40: Engine management systems - F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00) - 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 Methods and systems are provided for cycle-to-cycle torque reductions under exhaust component temperature constraints. In one example, a method may include, responsive to a torque reduction request, introducing a lambda split between two sets of cylinders over a plurality of engine cycles while maintaining an average of stoichiometry between the two sets of cylinders, and, responsive to reaching a lambda split threshold, introducing differentially delayed ignition timing in both sets of cylinders. In this way, fast torque reduction may be provided while maintaining a globally stoichiometric air-fuel ratio, thereby decreasing vehicle emissions, and reducing heat-related degradation to exhaust components. ## Claims ### Claim 1 A method, comprising: responsive to a torque reduction request while an exhaust temperature is greater than a threshold, operating an engine with a first number of cylinders enriched and a second number of cylinders enleaned, exhaust gas from both the first number and the second number producing a stoichiometric air-fuel ratio at a downstream catalyst, and adjusting spark timing in the first number of cylinders before adjusting spark timing in the second number of cylinders. ### Claim 2 (depends on 1) The method of claim 1, wherein the first number of cylinders includes a same number of cylinders as the second number of cylinders, and operating the engine with the first number of cylinders enriched and the second number of cylinders enleaned includes: determining a maximum air-fuel ratio difference for operating the first number of cylinders enriched and the second number of cylinders enleaned; and enriching the first number of cylinders and enleaning the second number of cylinders over one or more engine cycles until the maximum air-fuel ratio difference is reached, the stoichiometric air-fuel ratio maintained at the downstream catalyst each of the one or more engine cycles. ### Claim 3 (depends on 2) The method of claim 2, wherein adjusting the spark timing in the first number of cylinders before adjusting spark timing in the second number of cylinders includes, responsive to reaching the maximum air-fuel ratio difference, retarding a first spark timing in the first number of cylinders while maintaining a second spark timing in the second number of cylinders until a balanced torque output between the first number of cylinders and the second number of cylinders is achieved. ### Claim 4 (depends on 3) The method of claim 3, wherein adjusting the spark timing in the first number of cylinders before adjusting spark timing in the second number of cylinders further includes, responsive to the balanced torque output, further retarding the first spark timing while also retarding the second spark timing to a lesser degree and maintaining the balanced torque output until the torque reduction request is met. ### Claim 5 (depends on 1) The method of claim 1, wherein the first number of cylinders includes a first half of a total number of cylinders in the engine and the second number of cylinders includes a second half of the total number of cylinders in the engine. ### Claim 6 (depends on 1) The method of claim 1, wherein the torque reduction request includes one of a driver tip-out event and a transmission gear shift event. ### Claim 7 (depends on 1) The method of claim 1, wherein the exhaust temperature is a temperature of the downstream catalyst, and the exhaust gas temperature threshold is a threshold temperature of the downstream catalyst. ### Claim 8 (depends on 1) The method of claim 1, wherein the exhaust temperature is a temperature of a turbine positioned upstream of the downstream catalyst, and the threshold temperature is a threshold temperature of the turbine. ### Claim 9 (depends on 1) The method of claim 1, wherein operating the engine with the first number of cylinders enriched and the second number of cylinders enleaned produces a lower torque output than operating the first number of cylinders and the second number of cylinders at stoichiometry. ### Claim 10 A method, comprising: reducing engine torque over a plurality of engine cycles by increasing a difference between a rich air-fuel ratio (AFR) of a first set of engine cylinders and a lean AFR of a second set of engine cylinders and adjusting a first spark timing in the first set of cylinders prior to adjusting a second spark timing in the second set of cylinders, exhaust gas from the first set and the second set producing a stoichiometric mixture and remaining below a temperature threshold each engine cycle. ### Claim 11 (depends on 10) The method of claim 10, wherein increasing the difference between the rich AFR of the first set of engine cylinders and the lean AFR of the second set of engine cylinders occurs over a first portion of the plurality of engine cycles until a maximum difference is reached. ### Claim 12 (depends on 11) The method of claim 11, wherein the maximum difference is determined based on engine speed and load. ### Claim 13 (depends on 11) The method of claim 11, wherein adjusting the first spark timing in the first set of cylinders prior to adjusting the second spark timing in the second set of cylinders occurs during a second, remaining portion of the plurality of engine cycles. ### Claim 14 (depends on 10) The method of claim 10, wherein adjusting the first spark timing in the first set of cylinders prior to adjusting the second spark timing includes retarding the first spark timing in the first set of cylinders without adjusting the second spark timing in the second set of cylinders until a first torque output of the first set of cylinders is equal to a second torque output of the second set of cylinders, and then further retarding the first spark timing while also retarding the second spark timing while maintaining the first torque output equal to the second torque output. ### Claim 15 (depends on 10) The method of claim 10, wherein the threshold temperature is one of a threshold temperature of an emission control device and a threshold temperature of a turbocharger turbine. ### Claim 16 A system, comprising: a spark ignition engine including a plurality of cylinders; and a controller with computer readable instructions stored in non-transitory memory that, when executed during engine operation, cause the controller to: during a first condition, reduce engine torque by retarding spark timing by a same amount in every cylinder of the plurality of cylinders; and during a second condition, reduce engine torque by operating a first set of the plurality of cylinders at a rich air-fuel ratio and a second set of the plurality of cylinders at a lean air-fuel ratio while retarding spark timing differently in the first set and the second set. ### Claim 17 (depends on 16) The system of claim 16, further comprising an emission control device coupled in an exhaust passage, and wherein operating the first set of the plurality of cylinders at the rich air-fuel ratio and the second set of the plurality of cylinders at the lean air-fuel ratio produces a stoichiometric air-fuel ratio at the emission control device. ### Claim 18 (depends on 17) The system of claim 17, further comprising a turbocharger, including a turbine coupled in the exhaust passage upstream of the emission control device, and wherein the first condition includes a temperature of both the emission control device and an inlet of the turbine being less than a threshold and the second condition includes the temperature of at least one of the emission control device and the inlet of the turbine exceeding the threshold. ### Claim 19 (depends on 18) The system of claim 18, further comprising a first exhaust manifold coupled to the first set of the plurality of cylinders and a second exhaust manifold coupled to the second set of the plurality of cylinders, the first exhaust manifold separate from the second exhaust manifold upstream of the inlet of the turbine. ### Claim 20 (depends on 16) The system of claim 16, wherein the instructions that cause the controller to reduce engine torque by operating the first set of the plurality of cylinders at the rich air-fuel ratio and the second set of the plurality of cylinders at the lean air-fuel ratio while adjusting spark timing differently in the first set and the second set include further instructions stored in non-transitory memory that, when executed, cause the controller to: determine a maximum difference between the rich air-fuel ratio and the lean air-fuel ratio based on engine speed and load; increase the difference between the rich air-fuel ratio and the lean air-fuel ratio cycle-by-cycle until the maximum difference is reached; responsive to the difference between the rich air-fuel ratio and the lean air-fuel ratio reaching the maximum difference, retard the spark timing in the first set of the plurality of cylinders only until a balanced torque output between the first set of the plurality of cylinders and the second set of the plurality of cylinders is achieved; and responsive to achieving the balanced torque output, further retard the spark timing in the first set of the plurality of cylinders while also retarding the spark timing in the second set of the plurality of cylinders at different rate to maintain the balanced torque output until a desired reduced engine torque is met.