# US 10,119,465 B2 · Geared turbofan with independent flexible ring gears and oil collectors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,119,465 B2 - Document ID: US10119465B2 - Status: Granted - Kind: B2 - Application number: 15/182,909 - Filed: 2016-06-15 - Published: 2016-12-29 - Granted: 2018-11-06 - Earliest claimed: 2015-06-23 - Assignees: United Technologies Corporation - Applicants: United Technologies Corporation - Inventors: William G. Sheridan - Web page: https://patentgrep.com/patent/US10119465B2 ## CPC - F02C 3/107: with two or more rotors connected by power transmission - F01D 25/164: {Flexible supports; Vibration damping means associated with the bearing} - F01D 25/18: Lubricating arrangements (of machines or engines in general F01M) - F02C 7/06: Arrangements of bearings (bearings F16C); Lubricating ({of turbo machines F01D25/18; of machines or} engines in general F01M) - F02C 7/36: Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user ({F02C3/107 - F02C3/13 and} F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H) - F02K 3/06: with front fan - F16H 1/2818: {by allowing limited movement of the ring gear relative to the casing or shaft} - F16H 1/48: Special means compensating for misalignment of axes {, e.g. for equalising distribution of load on the face width of the teeth} - F05D 2220/323: for aircraft propulsion, e.g. jet engines - F05D 2230/64: using positioning or alignment devices for aligning or centring, e.g. pins - F05D 2240/35: Combustors or associated equipment - F05D 2240/54: Radial bearings - F05D 2240/60: Shafts - F05D 2250/611: undulated - F05D 2260/40311: of the epicyclical, planetary or differential type - F05D 2260/602: Drainage - F05D 2260/609: Deoiling or demisting - F05D 2260/98: Lubrication - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - 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) - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00) - F16H: GEARING - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A geared turbofan engine includes a fan rotatable about an engine axis. A compressor section compresses air and delivers the compressed air to a combustor where the compressed air is mixed with fuel and ignited to drive a turbine section that in turn drives the fan and the compressor section. A gear system is driven by the turbine section for driving the fan at a speed different than the turbine section. The gear system includes a carrier attached to a fan shaft. A plurality of planet gears are supported within the carrier. Each of the plurality of planet gears includes a first row of gear teeth and a second row of gear teeth supported within the carrier. A sun gear is driven by a turbine section. The sun gear is in driving engagement with the plurality of planet gears. At least two separate ring gears circumscribe the plurality of planet gears. Each of the at least two ring gears are supported by a respective flexible ring gear mount that enables movement relative to an engine static structure. A fan drive gear system for a gas turbine engine is also disclosed. ## Claims ### Claim 1 A geared turbofan engine comprising: a fan rotatable about an engine axis; a compressor section compressing air and delivering the compressed air to a combustor where the compressed air is mixed with fuel and ignited to drive a turbine section that in turn drives the fan and the compressor section; a gear system driven by the turbine section for driving the fan at a speed different than the turbine section, the gear system including: a carrier attached to a fan shaft; a plurality of planet gears supported within the carrier, wherein each of the plurality of planet gears includes a first row of gear teeth and a second row of gear teeth supported within the carrier; a sun gear driven by the turbine section, the sun gear in driving engagement with the plurality of planet gears; and at least two separate ring gears circumscribing the plurality of planet gears, wherein each of the at least two separate ring gears are supported by a separate flexible ring gear mount from a plurality of flexible ring gear mounts each separately attached to an engine static structure that enables movement of the at least two separate ring gears relative to the engine static structure, and wherein one of the plurality of flexible ring gear mounts includes a first axially curved section with respect to the engine axis that extends forward of the at least two separate ring gears with respect to the engine axis and another of the plurality of flexible ring gear mounts includes a second axially curved section with respect to the engine axis that extends aft of the at least two separate ring gears with respect to the engine axis and each of the plurality of flexible ring gear mounts include an opening in communication with a gutter that directs captured oil to an oil collection system. ### Claim 2 (depends on 1) The geared turbofan engine as recited in claim 1, wherein the sun gear includes a first set of gear teeth that meshes with the first row of gear teeth, and a second set of gear teeth that meshes with the second row of gear teeth. ### Claim 3 (depends on 1) The geared turbofan engine as recited in claim 1, including a first bearing assembly forward of the gear system supporting a forward portion of the fan shaft and a second bearing assembly aft of the gear system. ### Claim 4 (depends on 1) The geared turbofan engine as recited in claim 1, wherein the carrier and the fan shaft comprise an integral structure. ### Claim 5 (depends on 1) The geared turbofan engine as recited in claim 1, wherein the compressor section includes a low pressure compressor driven by the fan shaft at a speed common to the fan. ### Claim 6 (depends on 1) The geared turbofan engine as recited in claim 1, wherein oil is transported by one or more tubes to the oil collection system. ### Claim 7 (depends on 1) The geared turbofan engine as recited in claim 1, wherein each of the plurality of flexible ring gear mounts has equal stiffness to accommodate earner torsional wind up and reduce misalignment within the gear system. ### Claim 8 (depends on 7) The geared turbofan engine as recited in claim 7, wherein the plurality of flexible ring gear mounts enable the at least two separate ring gears to flex in a radial direction and an angular direction with respect to an engine centerline and are five (5) to ten (10) times stiffer in a torsional direction with respect to the engine centerline as compared to a stiffness in one of the radial direction and the angular direction. ### Claim 9 (depends on 1) The geared turbofan engine as recited in claim 1, wherein each of the plurality of planet gears is supported by one of a ball bearing, a roller bearing, a tapered roller bearing and a journal bearing. ### Claim 10 A fan drive gear system for a gas turbine engine, the fan drive gear system comprising: a carrier supporting a plurality of planet gears, wherein each of the plurality of planet gears includes a first row of gear teeth and a second row of gear teeth supported within the carrier; a sun gear driven by a turbine section, the sun gear in driving engagement with the plurality of planet gears; and at least two independent sets of ring gear teeth circumscribing the plurality of planet gears, each of the at least two independent sets of ring gear teeth are engaged with a corresponding one of the first row of gear teeth and the second row of gear teeth, wherein each of the at least two independent sets of ring gear teeth are supported by a respective flexible ring gear mount from a plurality of flexible ring gear mounts, that enables movement relative to an engine static structure, wherein one of the plurality of flexible ring gear mounts includes a first axially curved portion with respect to an engine centerline forward of the at least two independent sets of ring gear teeth with respect to the engine centerline, and another of the plurality of flexible ring gear mounts includes a second axially curved portion with respect to the engine centerline aft of the at least two independent sets of ring gear teeth with respect to the engine centerline, and each of the plurality of flexible ring gear mounts include an opening in communication with a gutter that directs captured oil to an oil collection system. ### Claim 11 (depends on 10) The fan drive gear system as recited in claim 10, wherein the sun gear includes a first set of gear teeth that meshes with the first row of gear teeth, and a second set of gear teeth that meshes with the second row of gear teeth. ### Claim 12 (depends on 10) The fan drive gear system as recited in claim 10, including a first bearing assembly forward of the fan drive gear system supporting a forward portion of a fan shaft and a second bearing assembly aft of the fan drive gear system. ### Claim 13 (depends on 12) The fan drive gear system as recited in claim 12, wherein the carrier and the fan shaft comprise an integral structure. ### Claim 14 (depends on 10) The fan drive gear system as recited in claim 10, wherein the plurality of flexible ring gear mounts enable the at least two independent sets of ring gear teeth to flex in a radial direction and an angular direction with respect to the engine centerline and are five (5) to ten (10) times stiffer in a torsional direction with respect to the engine centerline compared to a stiffness in one of the radial direction and the angular direction.