# US 2014/0155219 A1 · Turbine engine gearbox > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0155219 A1 - Document ID: US20140155219A1 - Status: Published application - Kind: A1 - Application number: 14/174,878 - Filed: 2014-02-07 - Published: 2014-06-05 - Earliest claimed: 2012-01-31 - Assignees: United Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Michael E. McCune; Ahmet Kahraman - Web page: https://patentgrep.com/patent/US20140155219A1 ## CPC - 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) - F01D 15/12: Combinations with mechanical gearing (driven by multiple engines F01D13/00) - F02K 3/04: the plant including ducted fans, i.e. fans with high volume, low pressure outputs, for augmenting the jet thrust, e.g. of double-flow type - F02K 3/072: with counter-rotating {, e.g. fan} rotors - F16H 1/28: with gears having orbital motion - F16H 1/46: Systems consisting of a plurality of gear trains each with orbital gears, {i.e. systems having three or more central gears} - F16H 57/0006: {Vibration-damping or noise reducing means specially adapted for gearings (devices for varying tension of belts, ropes or chains with damping means F16H7/0829; toothed members with construction providing vibration damping F16H55/14; reducing vibrations or noise of the gearbox casing F16H57/028; suppression of vibrations or noise of gear selectors F16H59/0208; control of hydrostatic fluid gearing preventing or reducing vibrations or noise F16H61/4183)} - F05D 2260/40311: of the epicyclical, planetary or differential type - 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 gas turbine engine comprises a fan, and a fan drive turbine rotor. The fan drive turbine drives the fan through a gear reduction. The gear reduction includes at least two double helical gears in meshed engagement. Each of the at least two double helical gears are disposed to rotate about respective axes, and each have a first plurality of gear teeth axially spaced from a second plurality of gear teeth by a spacer. Each of the first plurality of gear teeth has a first end facing the spacer and each of the second plurality of gear teeth has a first end facing the spacer. Each first end of the first plurality of gear teeth is circumferentially offset from each first end of the second plurality of gear teeth. ## Claims ### Claim 1 A gas turbine engine comprising: a fan; a fan drive turbine rotor to drive the fan through a gear reduction; and the gear reduction including at least two double helical gears in meshed engagement, each of the at least two double helical gears disposed to rotate about respective axes, and each of the at least two double helical gears having a first plurality of gear teeth axially spaced from a second plurality of gear teeth by a spacer, wherein each of the first plurality of gear teeth has a first end facing the spacer and each of the second plurality of gear teeth has a first end facing the spacer, with each first end of the first plurality of gear teeth being circumferentially offset from each first end of the second plurality of gear teeth. ### Claim 2 (depends on 1) The gas turbine engine as set forth in claim 1, wherein the fan drive turbine for driving a compressor rotor, along with the fan through the gear reduction. ### Claim 3 (depends on 2) The gas turbine engine as set forth in claim 2, wherein the first plurality of gear teeth are offset from the second plurality of gear teeth by a circumferential offset distance of about 25% to about 75% of the circumferential offset. ### Claim 4 (depends on 3) The gas turbine engine as set forth in claim 3, wherein the gear reduction includes an epicyclic gear system. ### Claim 5 (depends on 4) The gas turbine engine as set forth in claim 4, wherein the gear reduction is an epicyclic gear system that includes a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun gear and ring gear. ### Claim 6 (depends on 2) The gas turbine engine as set forth in claim 2, wherein the gearbox includes an epicyclic gear system. ### Claim 7 (depends on 6) The gas turbine engine as set forth in claim 6, wherein the gear reduction is an epicyclic gear system that includes a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun gear and ring gear. ### Claim 8 (depends on 2) The gas turbine engine as set forth in claim 2, wherein a gear ratio of the gear reduction being greater than or equal to about 2.5:1. ### Claim 9 (depends on 1) The gas turbine engine as set forth in claim 1, wherein there are two additional turbine rotors, with one of the two additional turbine rotors driving a low pressure compressor rotor, and a second of the additional turbine rotors driving a high pressure compressor rotor. ### Claim 10 (depends on 9) The gas turbine engine as set forth in claim 9, wherein a gear ratio of the gear reduction being greater than or equal to about 2.3:1. ### Claim 11 (depends on 9) The gas turbine engine as set forth in claim 9, wherein the gear reduction includes an epicyclic gear system. ### Claim 12 (depends on 11) The gas turbine engine as set forth in claim 11, wherein the gear reduction is an epicyclic gear system that includes a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun gear and ring gear. ### Claim 13 (depends on 1) The gas turbine engine as set forth in claim 1, wherein the gear reduction includes an epicyclic gear system. ### Claim 14 (depends on 13) The gas turbine engine as set forth in claim 13, wherein the first plurality of gear teeth and the second plurality of gear teeth about each double helical gear are disposed at a helix angle relative to an axis. ### Claim 15 (depends on 14) The gas turbine engine as set forth in claim 14, wherein the helix angle is between about 30-35°. ### Claim 16 (depends on 13) The gas turbine engine as set forth in claim 13, wherein a gear ratio of the gear reduction being greater than or equal to about 2.3:1. ### Claim 17 (depends on 1) The gas turbine engine as set forth in claim 1, wherein the fan drive turbine further driving a compressor rotor, with the compressor rotor also being driven through the gear reduction by the fan drive turbine rotor. ### Claim 18 (depends on 17) The gas turbine engine as set forth in claim 17, wherein the gear reduction includes an epicyclic gear system. ### Claim 19 (depends on 18) The gas turbine engine as set forth in claim 18, wherein the gear reduction is an epicyclic gear system that includes a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun gear and ring gear. ### Claim 20 (depends on 1) The gas turbine engine as set forth in claim 1, wherein a gear ratio of the gear reduction being greater than or equal to about 2.3:1. ### Claim 21 A method of designing a gas turbine engine comprising: providing a fan; providing a fan drive turbine rotor to drive the fan through a gear reduction; and the gear reduction including at least two double helical gears in meshed engagement, each of the at least two double helical gears disposed to rotate about respective axes, and each of the at least two double helical gears having a first plurality of gear teeth axially spaced from a second plurality of gear teeth by a spacer, wherein each of the first plurality of gear teeth has a first end facing the spacer and each of the second plurality of gear teeth has a first end facing the spacer, with each first end of the first plurality of gear teeth being circumferentially offset from each first end of the second plurality of gear teeth. ### Claim 22 (depends on 21) The method as set forth in claim 21, wherein the fan drive turbine for driving a compressor rotor, along with the fan through the gear reduction. ### Claim 23 (depends on 22) The method as set forth in claim 22, wherein the first plurality of gear teeth are offset from the second plurality of gear teeth by a circumferential offset distance of about 25% to about 75% of the circumferential offset. ### Claim 24 (depends on 23) The method as set forth in claim 23, wherein the gear reduction includes an epicyclic gear system. ### Claim 25 (depends on 24) The method as set forth in claim 24, wherein the gear reduction is an epicyclic gear system that includes a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun gear and ring gear. ### Claim 26 (depends on 22) The method as set forth in claim 22, wherein the gearbox includes an epicyclic gear system. ### Claim 27 (depends on 26) The method as set forth in claim 26, wherein the gear reduction is an epicyclic gear system that includes a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun gear and ring gear. ### Claim 28 (depends on 22) The method as set forth in claim 22, wherein a gear ratio of the gear reduction being greater than or equal to about 2.5:1. ### Claim 29 (depends on 21) The method as set forth in claim 21, wherein there are two additional turbine rotors, with one of the two additional turbine rotors driving a low pressure compressor rotor, and a second of the additional turbine rotors driving a high pressure compressor rotor. ### Claim 30 (depends on 29) The method as set forth in claim 29, wherein a gear ratio of the gear reduction being greater than or equal to about 2.3:1.