# US 11,994,079 B2 · Split cycle engine control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,079 B2 - Document ID: US11994079B2 - Status: Granted - Kind: B2 - Application number: 18/210,871 - Filed: 2023-06-16 - Published: 2023-10-19 - Granted: 2024-05-28 - Earliest claimed: 2019-02-26 - Assignees: Dolphin N2 Limited - Applicants: Dolphin N2 Limited - Inventors: Nick Owen; Andrew Atkins; Anoop Selvaraj - Web page: https://patentgrep.com/patent/US11994079B2 ## CPC - F02D 41/0007: {for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12)} - F02D 41/021: {Introducing corrections for particular conditions exterior to the engine (conjoint control of vehicle sub-units for propelling the vehicle B60W30/18)} - F02B 29/04: Cooling of air intake supply - F02B 33/44: Passages conducting the charge from the pump to the engine inlet, e.g. reservoirs - F02D 13/0215: {changing the valve timing only} - 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 41/401: {Controlling injection timing (F02D41/402 takes precedence)} - F02B 33/22: with pumping cylinder situated at side of working cylinder, e.g. the cylinders being parallel - F02B 37/18: by bypassing exhaust {from the inlet to the outlet of turbine or to the atmosphere} - F02D 19/12: peculiar to engines working with non-fuel substances or with anti-knock agents, e.g. with anti-knock fuel - F02D 35/025: {by determining temperatures inside the cylinder, e.g. combustion temperatures} - F02D 37/00: Non-electrical conjoint control of two or more functions of engines, not otherwise provided for - 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 41/064: {at cold start (F02D41/067 takes precedence)} - F02D 2041/001: {for engines with variable valve actuation} - F02D 2200/021: Engine temperature - F02D 2200/023: Temperature of lubricating oil or working fluid - F02D 2400/00: Control systems adapted for specific engine types; Special features of engine control systems not otherwise provided for; Power supply, connectors or cabling for engine control systems - Y02T 10/12: Improving ICE efficiencies - Y02T 10/40: Engine management systems - 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) - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract The split cycle engine of the present disclosure comprises a compression cylinder (10) accommodating a compression piston (12), a combustion cylinder (20) accommodating a combustion piston (22), a recuperator (35) arranged to exchange heat between exhaust fluid (95) from the combustion cylinder and working fluid being supplied from the compression cylinder to the combustion cylinder via a crossover passage (30). A controller is configured to control operation of the engine based on an indication of a temperature of at least one of a material of the recuperator and the working fluid in the crossover passage. ## Claims ### Claim 1 A split cycle internal combustion engine comprising: a compression cylinder accommodating a compression piston; a combustion cylinder accommodating a combustion piston; a recuperator arranged to exchange heat between exhaust fluid from the combustion cylinder and working fluid being supplied from the compression cylinder to the combustion cylinder; and a recuperator bypass passage selectively operable to enable at least some fluid to avoid flowing through the recuperator. ### Claim 2 (depends on 1) The split cycle internal combustion engine of claim 1, further comprising a controller configured to control usage of the recuperator bypass passage based on an indication of at least one operating parameter of the engine. ### Claim 3 (depends on 2) The split cycle internal combustion engine of claim 2, wherein said at least one operating parameter of the engine comprises a temperature of at least one of: (i) a material of the recuperator, and (ii) the working fluid to be supplied to the combustion cylinder. ### Claim 4 (depends on 2) The split cycle internal combustion engine of claim 2, wherein in the event that the indication of the operating parameter exceeds a threshold criterion, the controller is configured to control operation of the recuperator bypass passage to reduce a temperature of the recuperator and/or a temperature of the working fluid to be supplied to the combustion cylinder. ### Claim 5 (depends on 4) The split cycle internal combustion engine of claim 4, wherein controlling operation of the recuperator bypass passage to reduce a temperature of the recuperator comprises controlling operation of the recuperator bypass passage to reduce an average temperature of the fluid flowing through the recuperator. ### Claim 6 (depends on 4) The split cycle internal combustion engine of claim 4, wherein controlling operation of the recuperator bypass passage to reduce a temperature of the recuperator comprises at least one of: (i) increasing the amount of exhaust fluid from the combustion cylinder which bypasses the recuperator, and (ii) decreasing the amount of working fluid from the compression cylinder which bypasses the recuperator. ### Claim 7 (depends on 4) The split cycle internal combustion engine of claim 4, wherein controlling operation of the recuperator bypass passage to reduce a temperature of the working fluid to be supplied to the combustion cylinder comprises at least one of: (i) increasing the amount of exhaust fluid from the combustion cylinder which bypasses the recuperator, and (ii) increasing the amount of working fluid from the compression cylinder which bypasses the recuperator. ### Claim 8 (depends on 2) The split cycle internal combustion engine of claim 2, wherein in the event that the indication of the operating parameter does not satisfy a threshold criterion, the controller is configured to control operation of the recuperator bypass passage to increase a temperature of the recuperator and/or a temperature of the working fluid to be supplied to the combustion cylinder. ### Claim 9 (depends on 8) The split cycle internal combustion engine of claim 8, wherein controlling operation of the recuperator bypass passage to increase a temperature of the recuperator comprises controlling operation of the recuperator bypass passage to increase an average temperature of the fluid flowing through the recuperator. ### Claim 10 (depends on 8) The split cycle internal combustion engine of claim 8, wherein controlling operation of the recuperator bypass passage to increase a temperature of the recuperator comprises at least one of: (i) decreasing the amount of exhaust fluid from the combustion cylinder which bypasses the recuperator, and (ii) increasing the amount of working fluid from the compression cylinder which bypasses the recuperator. ### Claim 11 (depends on 8) The split cycle internal combustion engine of claim 8, wherein controlling operation of the recuperator bypass passage to increase a temperature of the working fluid to be supplied to the combustion cylinder comprises at least one of: (i) decreasing the amount of exhaust fluid from the combustion cylinder which bypasses the recuperator, and (ii) decreasing the amount of working fluid from the compression cylinder which bypasses the recuperator. ### Claim 12 (depends on 2) The split cycle internal combustion engine of claim 2, wherein the controller is configured to control operation of the recuperator bypass passage to control an amount of heat exchange occurring in the recuperator based on the indication of at least one operating parameter of the engine. ### Claim 13 (depends on 2) The split cycle internal combustion engine of claim 2, wherein the controller is configured to control operation of the recuperator bypass passage to reduce a temperature of a material of the recuperator in the event that the indicated parameter is a temperature which exceeds an upper threshold value. ### Claim 14 (depends on 2) The split cycle internal combustion engine of claim 2, wherein the controller is configured to control operation of the recuperator bypass passage to reduce an amount of heat-induced damage inflicted on the recuperator. ### Claim 15 (depends on 14) The split cycle internal combustion engine of claim 14, wherein controlling operation of the recuperator bypass passage based on the indication of the temperature comprises: in the event that the indicated temperature exceeds an upper threshold value, controlling operation of the recuperator bypass passage to reduce a temperature of the recuperator to reduce an amount of heat-induced damage inflicted on the recuperator. ### Claim 16 (depends on 1) The split cycle internal combustion engine of claim 1, wherein the recuperator bypass passage comprises: (i) a first passage for working fluid supplied from the compression cylinder, and (ii) a second passage for exhaust fluid from the combustion cylinder; and wherein the recuperator bypass passage comprises: a compressed fluid bypass passage for the working fluid supplied from the compression cylinder to bypass the first passage, and/or an exhaust fluid bypass passage for the exhaust fluid from the combustion cylinder to bypass the second passage. ### Claim 17 (depends on 1) The split cycle internal combustion engine of claim 1, wherein the recuperator bypass passage is arranged to enable recuperator bypass on both sides of the recuperator. ### Claim 18 (depends on 2) The split cycle internal combustion engine of claim 2, wherein the controller is configured to control opening and/or closing times of an exhaust valve of the combustion cylinder based on the obtained indication. ### Claim 19 A split cycle internal combustion engine comprising: a compression cylinder accommodating a compression piston; a combustion cylinder accommodating a combustion piston; a recuperator arranged to exchange heat between exhaust fluid from the combustion cylinder and working fluid being supplied from the compression cylinder to the combustion cylinder; a turbine arranged to be driven by the exhaust fluid flowing from the combustion cylinder to the recuperator; and a turbine bypass passage selectively operable to enable at least some of the exhaust fluid to flow to the recuperator without driving the turbine. ### Claim 20 A method of operating a split cycle internal combustion engine, the split cycle internal combustion engine comprising: a compression cylinder accommodating a compression piston; a combustion cylinder accommodating a combustion piston; a recuperator arranged to exchange heat between exhaust fluid from the combustion cylinder and working fluid being supplied from the compression cylinder to the combustion cylinder; and a recuperator bypass passage selectively operable to enable at least some fluid to avoid flowing through the recuperator; wherein the method comprises: obtaining an indication of at least one of: (i) a temperature associated with the combustion cylinder, and (ii) a temperature associated with the recuperator; and controlling use of the recuperator bypass passage based on the indicated temperature.