# US 11,306,669 B1 · System, apparatus, and method for controlling an engine system to account for varying fuel quality > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,306,669 B1 - Document ID: US11306669B1 - Status: Granted - Kind: B1 - Application number: 17/121,783 - Filed: 2020-12-15 - Granted: 2022-04-19 - Earliest claimed: 2020-12-15 - Assignees: Caterpillar Inc. - Applicants: Caterpillar Inc. - Inventors: Christopher F. Gallmeyer; Geetika Dilawari; Shawn M. Damm; Shivangi Wagle; Hannes Marscheider - Web page: https://patentgrep.com/patent/US11306669B1 ## CPC - F02D 19/10: peculiar to compression-ignition engines in which the main fuel is gaseous - F02D 41/0025: {Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures} - F02D 19/061: {by controlling fuel injectors} - F02D 19/0628: {Determining the fuel pressure, temperature or flow, the fuel tank fill level or a valve position} - F02D 41/0027: {the fuel being gaseous (non-electrical control F02D19/02)} - F02D 41/1446: {the characteristics being exhaust temperatures} - F02D 41/1461: {of the exhaust gases emitted by the engine} - F02D 2200/08: Exhaust gas treatment apparatus parameters - F02D 2200/0802: Temperature of the exhaust gas treatment apparatus - Y02T 10/30: Use of alternative fuels, e.g. biofuels - 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 A system, apparatus, and method for controlling an engine system can provide fuel reactivity compensation control for an engine of the engine system. The control can include controlling pilot fuel quantity supplied to an engine based on a pilot fuel offset value; and controlling air-to-fuel ratio (AFR) for the engine based on an AFR control trim value. A NOx error value can be used to generate one of the pilot fuel offset value or the AFR control trim value, and an exhaust temperature error value can be used to generate the other of the pilot fuel offset value or the AFR control trim value. ## Claims ### Claim 1 An engine control system for a dual fuel engine comprising: a nitrous oxide (NOx) sensor configured to sense NOx generated from operation of the dual fuel engine; and an engine control module (ECM) configured to control, in real time, pilot fuel quantity and air-to-fuel ratio (AFR) for the operation of the dual fuel engine, wherein the ECM includes a NOx controller and an exhaust temperature controller to perform fuel reactivity compensation, wherein the NOx controller is configured to generate, according to closed-loop control, a NOx error signal based on a comparison of an actual NOx signal from the NOx sensor and a desired NOx signal generated from a mapping operation of the NOx controller based on engine speed and engine load as inputs, wherein the exhaust temperature controller is configured to generate, according to closed-loop control, an exhaust temperature error signal based on a comparison of an actual exhaust temperature signal and a desired exhaust temperature signal generated from a mapping operation of the exhaust temperature controller based on the engine speed and the engine load as inputs, wherein one of the NOx controller and the exhaust temperature controller is configured to generate an additive pilot fuel offset signal and the other of the NOx controller and the exhaust temperature controller is configured to generate a multiplicative AFR control trim signal, and wherein the ECM is configured to output, at the same time, a pilot fuel quantity control signal generated from additive trimming according to the generated additive pilot fuel offset signal, and an AFR control signal generated from multiplicative trimming according to the generated multiplicative AFR control trim signal to decrease the NOx error signal and maintain the actual exhaust temperature signal within a predetermined, load-dependent exhaust temperature range. ### Claim 2 (depends on 1) The engine control system according to claim 1, wherein the NOx controller generates the additive pilot fuel offset signal using the NOx error signal, and wherein the exhaust temperature controller generates the multiplicative AFR control trim signal using the exhaust temperature error signal. ### Claim 3 (depends on 2) The engine control system according to claim 2, wherein the desired NOx signal is generated according to a first mapping operation of a first control module having the engine speed and the engine load as inputs, and wherein the desired exhaust temperature signal is generated according to a second mapping operation of a second control having the engine speed and the engine load as inputs. ### Claim 4 (depends on 1) The engine control system according to claim 1, wherein the NOx controller generates the multiplicative AFR control trim signal using the exhaust temperature error signal, and wherein the exhaust temperature controller generates the additive pilot fuel offset signal using the NOx error signal. ### Claim 5 (depends on 4) The engine control system according to claim 4, wherein the desired NOx signal is generated according to a first mapping operation of a first control module having engine speed and engine load as inputs, and wherein the desired exhaust temperature signal is generated according to a second mapping operation of a second control module having the engine speed and the engine load as inputs. ### Claim 6 (depends on 1) The engine control system according to claim 1, wherein the ECM is configured to output the pilot fuel quantity control signal to control an amount of liquid fuel supplied to the dual fuel engine. ### Claim 7 (depends on 1) The engine control system according to claim 1, wherein the ECM is configured to output the AFR control signal to control an AFR of air and gaseous fuel provided to the dual fuel engine. ### Claim 8 (depends on 1) The engine control system according to claim 1, wherein the additive pilot fuel offset signal is provided as feedback in said one of the NOx controller or the exhaust temperature controller. ### Claim 9 (depends on 1) The engine control system according to claim 1, wherein the multiplicative AFR control trim signal is provided as feedback in said other of the NOx controller or the exhaust temperature controller. ### Claim 10 A method of providing fuel reactivity compensation control for a dual fuel engine comprising: controlling, using control circuitry, pilot fuel quantity supplied to the dual fuel engine for operation of the dual fuel engine based on a generated pilot fuel offset signal; and controlling, using the control circuitry, air-to-fuel ratio (AFR) for the operation of the dual fuel engine based on a generated AFR control trim signal, wherein a NOx error value is used to generate one of the pilot fuel offset signal or the AFR control trim signal, and an exhaust temperature error value is used to generate the other of the pilot fuel offset signal or the AFR control trim signal, wherein the NOx error value is generated from a comparison of an actual NOx value from a NOx sensor and a desired NOx value produced from a first mapping operation based on engine speed and engine load as inputs, and wherein the exhaust temperature error value is generated from a comparison of an actual exhaust temperature value and a desired exhaust temperature value produced from a second mapping operation based on the engine speed and the engine load as inputs. ### Claim 11 (depends on 10) The method according to claim 10, further comprising determining an operating condition of the dual fuel engine and switching between which of the NOx error value and the exhaust temperature error value is used to generate the pilot fuel offset signal and the AFR control trim signal, respectively, responsive to the determined operating condition meeting a predetermined parameter. ### Claim 12 (depends on 10) The method according to claim 10, wherein said controlling the pilot fuel quantity includes generating a pilot fuel quantity control value having a pilot fuel offset value associated with the generated pilot fuel offset signal as an addend, and wherein said controlling the AFR includes generating an AFR control value having an AFR control trim value associated with the AFR control trim signal as a multiplier. ### Claim 13 (depends on 10) The method according to claim 10, further comprising maintaining each of the NOx error value and the exhaust temperature error value to within respective predetermined ranges by said controlling the pilot fuel quantity and said controlling the AFR at the same time during the operation of the dual fuel engine. ### Claim 14 (depends on 10) The method according to claim 10, wherein the NOx error value is determined according to a first mapping operation having engine speed and engine load as inputs, and wherein the exhaust temperature error value is determined according to a second mapping operation having the engine speed and the engine load as inputs. ### Claim 15 A non-transitory computer-readable storage medium having stored thereon instructions that, when executed by one or more processors, cause the one or more processors to perform an engine control method comprising: controlling pilot fuel quantity supplied to an engine based on a generated pilot fuel offset value; and controlling air-to-fuel ratio (AFR) for the engine based on a generated AFR control trim value, wherein a NOx error value is used to generate one of the pilot fuel offset value or the AFR control trim value, and an exhaust temperature error value is used to generate the other of the pilot fuel offset value or the AFR control trim value, wherein said controlling the pilot fuel quantity includes generating a pilot fuel quantity control value having the generated pilot fuel offset value as an addend, and wherein said controlling the AFR includes generating an AFR control value having the generated AFR control trim value as a multiplier. ### Claim 16 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein the NOx error value is generated based on a comparison of actual NOx from a NOx sensor and desired NOx determined from a mapping operation having engine speed and engine load as inputs. ### Claim 17 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein the exhaust temperature error signal is generated based on a comparison of an actual exhaust temperature signal and a desired exhaust temperature signal determined according to a mapping operation having engine speed and engine load as inputs. ### Claim 18 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein the engine control method further comprises maintaining each of the NOx error value and the exhaust temperature error value below respective predetermined thresholds by said controlling the pilot fuel quantity and said controlling the AFR at the same time during the operation of the engine. ### Claim 19 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein the pilot fuel offset signal and the AFR control trim signal are provided separately as feedback for said controlling the pilot fuel quantity and said said controlling the AFR.