# US 7,407,369 B2 · Gas turbine engine blade tip clearance apparatus and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,407,369 B2 - Document ID: US7407369B2 - Status: Granted - Kind: B2 - Application number: 11/253,235 - Filed: 2005-10-17 - Published: 2006-06-29 - Granted: 2008-08-05 - Earliest claimed: 2004-12-29 - Assignees: United Technologies Corporation - Inventors: Frederick M. Schwarz; J. Walter Smith - Web page: https://patentgrep.com/patent/US7407369B2 ## CPC - F01D 11/122: {with erodable or abradable material (blades having cutting or grinding tips F01D5/20)} - F01D 11/22: by mechanically actuating the stator or rotor components, e.g. moving shroud sections relative to the rotor - F01D 21/04: responsive to undesired position of rotor relative to stator {or to breaking-off of a part of the rotor}, e.g. indicating such position - F04D 29/052: Axially shiftable rotors (F04D29/051 takes precedence {; control by creating a by-pass F04D27/0246}) - F16C 23/06: Ball or roller bearings - F05D 2260/403: through the shape of the drive components - F16C 2360/23: Gas turbine engines - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS - 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 zero running clearance system for gas turbine engines includes a gas turbine engine compressor having one or more first rotor assemblies and one or more first stator assemblies disposed adjacent the one or more first rotor assemblies; a gas turbine engine turbine having one or more second rotor assemblies and one or more second stator assemblies disposed adjacent the one or more second rotor assemblies; one or more shroud segments having blade seal surfaces disposed radially outside of the tips of blades of both the first and second rotor assemblies and a clearance distance extending between the blade tips and blade seal surfaces; and, an actuator selectively operable to axially move the first and said second rotor assemblies to alter the clearance distance. ## Claims ### Claim 1 A zero running clearance system for gas turbine engines, comprising: one or more first rotor assemblies of a gas turbine engine compressor rotatable around an axially extending rotational axis, each first rotor assembly having a plurality of blades with each blade having a tip; one or more first stator assemblies of said gas turbine engine compressor disposed adjacent said one or more first rotor assemblies; one or more first shroud segments having blade seal surfaces disposed radially outside of said one or more first rotor assemblies; one or more second rotor assemblies of a gas turbine engine turbine rotatable around said axially extending rotational axis, each second rotor assembly having a plurality of blades with each blade having a tip; one or more second stator assemblies of said gas turbine engine turbine disposed adjacent said one or more second rotor assemblies; one or more second shroud segments having blade seal surfaces disposed radially outside of said one or more second rotor assemblies; wherein said blade tips and said blade seal surfaces have mating geometries and a clearance distance extending between said blade tips and said blade seal surfaces; and an actuator selectively operable to axially move said first rotor assemblies and said second rotor assemblies to alter said clearance distance; wherein said actuator includes a screw thread device, wherein said screw thread device is mounted such that both said first rotor assemblies and said second rotor assemblies move axially in unison when at least a portion of the screw thread device rotates. ### Claim 2 (depends on 1) The zero running clearance system of claim 1, wherein said screw thread device includes a threaded engagement between a member disposed movable relative to said one or more first rotor assemblies and second rotor assemblies. ### Claim 3 (depends on 1) The zero running clearance system of claim 1, wherein said screw thread device comprises a ball screw assembly. ### Claim 4 (depends on 3) The zero running clearance system of claim 3, wherein said ball screw assembly includes a rotatable first member, and a second member attached to said one or more first rotor assemblies and second rotor assemblies. ### Claim 5 (depends on 1) The zero running clearance system of claim 1, wherein said gas turbine engine compressor comprises a low pressure compressor and a high pressure compressor, and wherein said actuator is selectively operable to axially move a plurality of first rotor assemblies within said high pressure compressor. ### Claim 6 (depends on 1) The zero running clearance system of claim 1, wherein said gas turbine engine turbine comprises a low pressure turbine and a high pressure turbine, and wherein said actuator is selectively operable to axially move a plurality of second rotor assemblies within said high pressure turbine. ### Claim 7 (depends on 1) The zero running clearance system of claim 1, wherein said gas turbine engine compressor comprises a low pressure compressor and a high pressure compressor, and wherein said actuator is selectively operable to axially move a plurality of first rotor assemblies within said low pressure compressor. ### Claim 8 (depends on 1) The zero running clearance system of claim 1, wherein said gas turbine engine turbine comprises a low pressure turbine and a high pressure turbine, and wherein said actuator is selectively operable to axially move a plurality of second rotor assemblies within said low pressure turbine. ### Claim 9 (depends on 1) The zero running clearance system of claim 1, wherein said actuator is selectively operable to axially move in unison said first rotor assemblies and said second rotor assemblies. ### Claim 10 (depends on 1) The zero running clearance system of claim 1, further comprising one or more sensors for sensing said clearance distance. ### Claim 11 (depends on 1) The zero running clearance system of claim 1, wherein said one or more first stator assemblies and said one or more second stator assemblies are each cantilevered. ### Claim 12 A method for controlling blade tip clearance within a gas turbine engine, comprising: providing a compressor having one or more first rotor assemblies, each first rotor assembly having a plurality of blades with each blade having a blade tip, one or more first stator assemblies disposed adjacent said one or more first rotor assemblies, and a shroud having one or more blade seal surfaces disposed radially outside of said one or more first rotor assemblies, wherein said blade tips in each of said one or more first rotor assemblies has a mating geometry with at least one of said one or more blade seal surfaces, and a clearance distance extending between said blade tips and said blade seal surfaces; providing a turbine having one or more second rotor assemblies, each second rotor assembly having a plurality of blades with each blade having a blade tip, one or more second stator assemblies disposed adjacent said one or more second rotor assemblies, and said shroud having one or more blade seal surfaces disposed radially outside of said one or more second rotor assemblies, wherein said blade tips in each of said one or more second rotor assemblies has a mating geometry with at least one of said one or more blade seal surfaces, and a clearance distance extending between said blade tips and said blade seal surfaces; providing an actuator selectively operable to axially move said one or more rotor assemblies relative to said shroud said actuator includes a screw thread device disposed in connection with the one or more rotor assemblies; and axially moving said one or more first rotor assemblies and second rotor assemblies relative to said shroud using said screw thread device to alter said clearance distance. ### Claim 13 (depends on 12) The method of claim 12, further comprising the steps of: providing a desired clearance distance extending between said blade tips and said blade seal surfaces for a given set of operating conditions; sensing an actual clearance distance extending between said blade tips and said blade seal surfaces; comparing said desired clearance distance to said sensed actual clearance distance to determine a difference value; and axially moving in unison said one or more first rotor assemblies and second rotor assemblies relative to said shroud using said actuator in a direction that decreases said difference value. ### Claim 14 (depends on 12) The method of claim 12, wherein axially moving comprises axially moving said one or more first rotor assemblies and second rotor assemblies in unison. ### Claim 15 (depends on 12) The method of claim 12, wherein one or more first stator assemblies and said one or more second stator assemblies are each cantilevered.