# US 2018/0023481 A1 · Multi-spool gas turbine engine architecture > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0023481 A1 - Document ID: US20180023481A1 - Status: Published application - Kind: A1 - Application number: 15/384,959 - Filed: 2016-12-20 - Published: 2018-01-25 - Earliest claimed: 2016-07-19 - Assignees: Pratt & Whitney Canada Corp. - Applicants: Pratt & Whitney Canada Corp. - Inventors: Guy LEFEBVRE - Web page: https://patentgrep.com/patent/US20180023481A1 ## 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) - B64D 27/10: of gas-turbine type (jet aircraft B64D27/16) - B64D 35/04: characterised by the transmission driving a plurality of propellers or rotors - F01D 5/026: {Shaft to shaft connections} - F01D 15/12: Combinations with mechanical gearing (driven by multiple engines F01D13/00) - F01D 25/18: Lubricating arrangements (of machines or engines in general F01M) - F02C 3/08: the compressor comprising at least one radial stage (F02C3/10 takes precedence) - F02C 3/10: with another turbine driving an output shaft but not driving the compressor - F02C 3/107: with two or more rotors connected by power transmission - F02C 3/113: with variable power transmission between rotors - F02C 3/145: {the combustion chamber being in the reverse flow-type} - F02C 6/206: {the vehicles being airscrew driven} - F02C 7/06: Arrangements of bearings (bearings F16C); Lubricating ({of turbo machines F01D25/18; of machines or} engines in general F01M) - F02C 7/32: Arrangement, mounting, or driving, of auxiliaries - F02K 3/06: with front fan - F16H 57/0495: {with fixed gear ratio} - F05D 2220/32: in gas turbines - F05D 2220/323: for aircraft propulsion, e.g. jet engines - F05D 2220/324: to drive unshrouded, low solidity propeller - F05D 2220/329: in helicopters - F05D 2230/70: Disassembly methods - F05D 2230/72: Maintenance - F05D 2240/61: Hollow - F05D 2250/36: in inner-outer relationship, e.g. shaft-bearing arrangements - F05D 2260/31: Retaining bolts or nuts - F05D 2260/36: by a form fit connection, e.g. by interlocking - F05D 2260/40: Transmission of power - F05D 2260/4031: as in toothed gearing - F05D 2260/40311: of the epicyclical, planetary or differential type - F05D 2260/98: Lubrication - Y02T 50/40: Weight reduction - 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) - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - 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 multi-spool gas turbine engine comprises a low pressure (LP) spool and a high pressure (HP) spool independently rotatable about a central axis. The LP pressure spool has an LP compressor and an LP turbine. The HP spool has an HP turbine and an HP compressor. An accessory gear box (AGB) is drivingly connected to the HP spool. The LP compressor is disposed axially between the HP compressor and the AGB. A gear train drivingly couples the LP compressor to the LP turbine. The gear train is integrated to the AGB. ## Claims ### Claim 1 A reverse flow gas turbine engine comprising: a low pressure (LP) spool and a high pressure (HP) spool rotatable independently of one another about an engine axis; the LP spool comprising an LP turbine, an LP compressor and an LP shaft drivingly connected to the LP turbine, the LP turbine disposed forward of the LP compressor relative to a direction of travel of the engine; the HP spool comprising an HP turbine, an HP compressor and an HP shaft drivingly connecting the HP turbine to the HP compressor, the HP compressor disposed forward of the LP compressor and in fluid communication therewith, the HP turbine disposed aft of the LP turbine and in fluid communication therewith; an accessory gear box (AGB) drivingly connected to the HP spool, the LP compressor disposed axially between the HP compressor and the AGB, and a gear train drivingly coupling the LP shaft to the LP compressor, the gear train disposed aft of the LP compressor. ### Claim 2 (depends on 1) The reverse flow gas turbine engine defined in claim 1, wherein the gear train coupling the LP shaft to the LP compressor and the AGB share a common housing. ### Claim 3 (depends on 1) The reserve flow gas turbine engine defined in claim 1, wherein the LP shaft extends axially through a central bore of the LP compressor and projects axially aft of the LP compressor. ### Claim 4 (depends on 3) The reverse flow gas turbine engine defined in claim 3, wherein the LP shaft extends into the AGB. ### Claim 5 (depends on 3) The reserve flow gas turbine engine defined in claim 3, wherein the gear train is disposed in the AGB and is drivingly coupled to an aft end of the LP shaft. ### Claim 6 (depends on 1) The reverse flow gas turbine engine defined in claim 1, wherein the gear train is a dual gear train comprising first and second drive inputs to the LP compressor. ### Claim 7 (depends on 5) The reverse flow gas turbine engine defined in claim 5, wherein the gear train comprises first and second sets of gears, the LP shaft being drivingly coupled to both said first and second sets of gears for driving the LP compressor. ### Claim 8 (depends on 1) The reverse flow gas turbine engine defined in claim 1, wherein the LP shaft is a one piece shaft having a power turbine shaft portion extending forwardly of the LP turbine and a LP compressor shaft portion extending rearwardly from the LP turbine to a location aft of the LP compressor. ### Claim 9 (depends on 8) The reverse flow gas turbine engine defined in claim 8, wherein the LP shaft extends centrally through the HP shaft, and wherein the LP shaft is supported by at least one bearing mounted in an internal cavity disposed between the HP compressor and the LP compressor and radially inwardly of an annular gas path between the HP compressor and LP compressor. ### Claim 10 (depends on 9) The reverse flow gas turbine engine defined in claim 9, wherein the HP shaft comprises a first shaft section projecting aft of the HP compressor and a second shaft section projecting axially through the LP compressor into the AGB, and wherein a gear is disposed in the internal cavity to drivingly connect the first shaft section to the second shaft section. ### Claim 11 (depends on 10) The reverse flow gas turbine engine defined in claim 10, wherein the gear is a bevel gear having a rotation axis perpendicular to the engine axis. ### Claim 12 (depends on 1) The reverse flow gas turbine engine defined in claim 1, comprising a split casing including first and second separable casing sections having an interface between the HP compressor and the LP compressor to provide access to an internal cavity disposed radially inwardly of an annular gaspath between the LP and HP compressors, the internal cavity housing at least one bearing supporting the LP shaft. ### Claim 13 (depends on 12) The reverse flow gas turbine engine defined in claim 12, wherein the HP shaft has a first shaft section projecting aft of the HP compressor and a second shaft section projecting axially through the LP compressor into the AGB, and wherein the first and second shaft sections are drivingly connected by a bevel gear housed in the internal cavity, the at least one bearing being disposed between said first and second shaft sections of the HP shaft. ### Claim 14 (depends on 1) The reverse flow gas turbine engine defined in claim 1, wherein the AGB has an input axis coaxial to the engine axis. ### Claim 15 (depends on 14) The reverse flow gas turbine engine defined in claim 14, wherein the HP shaft extends axially through a central bore of the LP compressor and project axially aft of the LP compressor in driving engagement with the AGB. ### Claim 16 A multi-spool gas turbine engine comprising: a low pressure (LP) spool; a high pressure (HP) spool, the LP spool and the HP spool rotatable independently of one another about a central axis, the LP pressure spool comprising an LP compressor and an LP turbine, the HP spool comprising an HP turbine and an HP compressor; an accessory gear box (AGB) drivingly connected to the HP spool, the LP compressor disposed axially between the HP compressor and the AGB, and a gear train drivingly coupling the LP compressor to the LP turbine, the gear train disposed on an AGB facing side of the LP compressor. ### Claim 17 (depends on 16) The multi-spool gas turbine engine defined in claim 16, wherein the LP spool comprises an LP shaft extending axially from the LP turbine through a central bore of the LP compressor and in driving engagement with the gear train. ### Claim 18 (depends on 17) The multi-spool gas turbine engine defined in claim 17, wherein the LP compressor has a hollow compressor shaft portion extending concentrically about the LP shaft on the AGB facing side of the LP compressor, the hollow compressor shaft portion being drivingly connected to the LP shaft by the gear train. ### Claim 19 (depends on 18) The multi-spool gas turbine engine defined in claim 18, wherein the HP spool comprises a HP shaft drivingly connected to the HP turbine and extending axially though the central bore of the LP compressor between the LP shaft and the hollow compressor shaft portion of the LP compressor, the HP shaft being drivingly connected to the AGB. ### Claim 20 (depends on 19) The multi-spool gas turbine engine defined in claim 19, wherein the LP shaft extends into the AGB axially beyond the HP shaft and the hollow compressor shaft portion of the LP compressor. ### Claim 21 (depends on 20) The multi-spool gas turbine engine defined in claim 20, wherein the HP shaft ends axially between the hollow compressor shaft portion of the LP compressor and the LP shaft. ### Claim 22 (depends on 19) The multi-spool gas turbine engine defined in claim 19, wherein the HP shaft comprises first and second shaft sections drivingly coupled by a bevel gear disposed in a cavity between the HP compressor and the LP compressor radially inwardly of a gas path between the HP and LP compressors. ### Claim 23 (depends on 22) The multi-spool gas turbine engine defined in claim 22, wherein at least one bearing is provided in the cavity between the first and second shaft sections of the HP shaft, the at least one bearing supporting the LP shaft. ### Claim 24 (depends on 17) The multi-spool gas turbine engine defined in claim 17, wherein the gear train is a dual gear train comprising first and second sets of gears respectively disposed on opposed lateral sides of the LP shaft to provide first and second drive inputs to the LP compressor. ### Claim 25 (depends on 22) The multi-spool gas turbine engine defined in claim 22, wherein the cavity is defined by first and second casing sections having a mounting interface disposed between the HP compressor and the LP compressor, the first and second casing sections being separable to provide access to said cavity. ### Claim 26 (depends on 16) The multi-spool gas turbine engine defined in claim 16, wherein the engine is an aircraft engine having a reverse flow configuration including an air inlet disposed aft of the LP compressor along a direction of travel of the aircraft engine, and wherein the AGB is disposed aft of the air inlet.