# US 12,595,763 B2 · Gas turbine engine hydraulic system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,595,763 B2 - Document ID: US12595763B2 - Status: Granted - Kind: B2 - Application number: 19/096,780 - Filed: 2025-04-01 - Published: 2025-10-23 - Granted: 2026-04-07 - Earliest claimed: 2024-04-18 - Assignees: ROLLS-ROYCE plc - Applicants: ROLLS-ROYCE plc - Inventors: Adam Newman; Chloe J. Palmer; Benjamin J Keeler; Richard A Scott - Web page: https://patentgrep.com/patent/US12595763B2 ## CPC - F02C 7/224: Heating fuel before feeding to the burner - F02C 6/00: Plural gas-turbine plants; Combinations of gas-turbine plants with other apparatus; Adaptations of gas-turbine plants for special use - F02C 7/16: characterised by cooling medium - F02C 7/22: Fuel supply systems - F02C 9/40: specially adapted to the use of a special fuel or a plurality of fuels - F02C 3/22: the fuel or oxidant being gaseous at standard temperature and pressure (F02C3/28 takes precedence) - F05D 2260/213: by the provision of a heat exchanger within the cooling circuit - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A hydraulic system for a hydrogen fueled gas turbine engine. The hydraulic system comprises a closed-loop hydraulic fluid conduit, a hydrogen-hydraulic fluid heat exchanger configured to exchange heat between cryogenic hydrogen fuel and hydraulic fluid within the hydraulic fluid conduit, and a second fuel-hydraulic heat exchanger configured to exchange heat between a second, non-hydrogen fuel and hydraulic fluid in the hydraulic fluid conduit. ## Claims ### Claim 1 A hydraulic system for a hydrogen fueled gas turbine engine, the hydraulic system comprising: a closed-loop hydraulic fluid conduit; a hydrogen-hydraulic fluid heat exchanger configured to exchange heat between cryogenic hydrogen fuel and hydraulic fluid within the hydraulic fluid conduit; a second fuel-hydraulic heat exchanger configured to exchange heat between a second, non-hydrogen fuel and hydraulic fluid in the hydraulic fluid conduit; a hydrogen fuel circuit configured to flow the hydrogen fuel through the hydrogen-hydraulic fluid heat exchanger but not the second fuel-hydraulic heat exchanger; and a second fuel circuit configured to flow the non-hydrogen fuel through the second fuel-hydraulic heat exchanger but not the hydrogen-hydraulic fluid heat exchanger. ### Claim 2 (depends on 1) A hydraulic system according to claim 1, wherein the hydraulic system comprises a third fuel-hydraulic heat exchanger configured to exchange heat between a third, non-hydrogen fuel and hydraulic fluid in the hydraulic fluid conduit. ### Claim 3 (depends on 1) A hydraulic system according to claim 1, wherein the second and/or third fuel comprises kerosene and/or methane. ### Claim 4 (depends on 1) A hydraulic system according to claim 1, wherein the hydrogen-hydraulic fluid heat exchanger and second fuel-hydraulic and optional third fuel-hydraulic heat exchangers are provided in hydraulic fluid flow series. ### Claim 5 (depends on 1) A hydraulic system according to claim 1, wherein the hydraulic system comprises first and/or second fuel-hydraulic bypass lines configured to selectively bypass a respective fuel-hydraulic heat exchanger. ### Claim 6 (depends on 1) A hydraulic system according to claim 1, wherein the hydraulic system comprises a further heat exchanger configured to exchange heat between the hydraulic fluid and one or more further engine fluids. ### Claim 7 (depends on 1) A system according to claim 1, wherein the hydraulic system comprises a hydraulic pump configured to pressurise and drive hydraulic fluid flow through the hydraulic fluid conduit. ### Claim 8 (depends on 7) A system according to claim 7, wherein the hydraulic pump is provided upstream in fluid flow of the hydrogen-hydraulic fluid heat exchanger. ### Claim 9 (depends on 8) A system according to claim 8, wherein the hydraulic pump is configured to provide a total hydraulic fluid pressure within the hydrogen-hydraulic fluid heat exchanger equal to or greater than a hydrogen fuel pressure within the hydrogen-hydraulic fluid heat exchanger. ### Claim 10 (depends on 1) A system according to claim 1, wherein the hydraulic system comprises one or more hydraulically actuated actuators. ### Claim 11 (depends on 6) A system according to claim 6, wherein the hydraulic system comprises a restrictor downstream in hydraulic fluid flow of the hydrogen-hydraulic fluid heat exchanger, and upstream of the further heat exchanger. ### Claim 12 (depends on 11) A system according to claim 11, wherein the restrictor is upstream of one or more components cooled by hydraulic fluid. ### Claim 13 (depends on 12) A system according to claim 12, wherein the hydraulic system comprises a high-pressure sub-loop upstream of the restrictor and configured to provide hydraulic actuation fluid to one or more hydraulic actuators. ### Claim 14 (depends on 12) A system according to claim 12, wherein the hydraulic system comprises a high-pressure hydraulic accumulator configured to provide hydraulic fluid to the high-pressure sub-loop and to the restrictor. ### Claim 15 (depends on 6) A system according to claim 6, wherein the further heat exchanger is configured to exchange heat between hydraulic fluid and oil. ### Claim 16 (depends on 1) A gas turbine engine comprising a hydraulic system in accordance with claim 1.