# US 12,215,590 B2 · Method for checking bleed-off valve closing point > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,215,590 B2 - Document ID: US12215590B2 - Status: Granted - Kind: B2 - Application number: 17/828,837 - Filed: 2022-05-31 - Published: 2023-11-30 - Granted: 2025-02-04 - Earliest claimed: 2022-05-31 - Assignees: Pratt & Whitney Canada Corp. - Applicants: Pratt & Whitney Canada Corp. - Inventors: Louis Duranleau-Hendrickx - Web page: https://patentgrep.com/patent/US12215590B2 ## CPC - F01D 21/003: {Arrangements for testing or measuring (for measuring vibrations G01H)} - F02C 6/08: the gas being bled from the gas-turbine compressor - F02C 9/18: by bleeding, bypassing or acting on variable working fluid interconnections between turbines or compressors or their stages {(F02C3/113 takes precedence)} - F04D 27/0207: {by bleeding, bypassing or recycling fluids (influencing the boundary layer by an uncontrolled bleeding of the working fluid F04D29/681)} - F05D 2260/606: Bypassing the fluid - F05D 2260/80: Diagnostics - F05D 2260/83: Testing, e.g. methods, components or tools therefor - F05D 2270/101: Compressor surge or stall - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - 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) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A method for checking a closing point for a bleed-off valve for a gas turbine engine includes determining a modulation characteristic curve for the bleed-off valve, determining a nominal closing point value for the bleed-off valve on the modulation characteristic curve, operating the gas turbine engine and increasing an engine power of the gas turbine engine until the gas turbine engine parameter reaches a predetermined testing value, and determining a bleed-off valve measured value and a gas turbine engine measured value when the gas turbine engine parameter reaches the predetermined testing value. The gas turbine engine measured value is different than the nominal closing point value. The method further includes determining an extrapolated closing point value and checking the closing point for the bleed-off valve by comparing the bleed-off valve measured value or the gas turbine engine measured value to the extrapolated closing point value. ## Claims ### Claim 1 A method for checking a closing point for a bleed-off valve for a gas turbine engine, the method comprising: determining a modulation characteristic curve for the bleed-off valve, the modulation characteristic curve is a function of a bleed-off valve parameter and a gas turbine engine parameter; determining a nominal closing point value for the bleed-off valve on the modulation characteristic curve, the nominal closing point value is a value of the gas turbine engine parameter; operating the gas turbine engine and increasing an engine power of the gas turbine engine until the gas turbine engine parameter reaches a predetermined testing value; determining a bleed-off valve measured value of the bleed-off valve parameter and a gas turbine engine measured value of the gas turbine engine parameter when the gas turbine engine parameter reaches the predetermined testing value, the gas turbine engine measured value is different than the nominal closing point value; determining, using the modulation characteristic curve, an extrapolated closing point value of the gas turbine engine parameter based on the bleed-off valve measured value; and checking the closing point for the bleed-off valve by comparing the gas turbine engine measured value to the extrapolated closing point value, where the extrapolated closing point value is a value of the gas turbine engine parameter. ### Claim 2 (depends on 1) The method of claim 1, wherein the step of determining the modulation characteristic curve includes determining an altitude and an inlet air temperature for the gas turbine engine, the modulation characteristic curve based, at least in part, on the altitude and the inlet air temperature. ### Claim 3 (depends on 1) The method of claim 1, wherein the bleed-off valve parameter is a bleed-off valve outlet pressure. ### Claim 4 (depends on 1) The method of claim 1, wherein the gas turbine engine parameter is an engine speed of the gas turbine engine. ### Claim 5 (depends on 1) The method of claim 1, wherein the predetermined testing value is an engine operating limit for the gas turbine engine. ### Claim 6 (depends on 5) The method of claim 5, wherein the nominal closing point value is outside of the engine operating limit for the gas turbine engine. ### Claim 7 (depends on 1) The method of claim 1, wherein the predetermined testing value is a non-limiting value. ### Claim 8 (depends on 1) The method of claim 1, further comprising adjusting the closing point for the bleed-off valve if the gas turbine engine measured value is outside of a predetermined tolerance range of the extrapolated closing point value. ### Claim 9 (depends on 1) The method of claim 1, wherein the gas turbine engine includes a compressor section which defines a portion of a core flow path through the gas turbine engine; the bleed-off valve is in fluid communication with the core flow path within the compressor section via a pressure relief line; and the step of operating the gas turbine engine includes regulating a pressure of core gas within the compressor section by bleeding core gas from the core flow path with the bleed-off valve. ### Claim 10 (depends on 9) The method of claim 9, wherein the bleed-off valve is in fluid communication with the core flow path within an intermediate stage of a compressor of the compressor section. ### Claim 11 A method for checking a closing point for a bleed-off valve for a gas turbine engine, the method comprising: determining a modulation characteristic curve for the bleed-off valve, the modulation characteristic curve is a function of a bleed-off valve outlet pressure of the bleed-off valve and an engine speed of the gas turbine engine; operating the gas turbine engine and increasing an engine power of the gas turbine engine until the engine speed reaches a predetermined testing value; determining a bleed-off valve measured value of the bleed-off valve outlet pressure and a gas turbine engine measured value of the engine speed when the engine speed reaches the predetermined testing value; determining an extrapolated closing point value of the engine speed based on the bleed-off valve outlet pressure, the extrapolated closing point value corresponds to the engine speed of the modulation characteristic curve at the bleed-off valve measured value of the bleed-off valve outlet pressure; and checking the closing point for the bleed-off valve by comparing the gas turbine engine measured value to a predetermined tolerance range of the extrapolated closing point value. ### Claim 12 (depends on 11) The method of claim 11, wherein the step of determining the modulation characteristic curve includes determining an altitude and an inlet air temperature for the gas turbine engine, the modulation characteristic curve based, at least in part, on the altitude and the inlet air temperature. ### Claim 13 (depends on 11) The method of claim 11, further comprising adjusting the closing point for the bleed-off valve if the gas turbine engine measured value is outside of the predetermined tolerance range of the extrapolated closing point value. ### Claim 14 (depends on 11) The method of claim 11, further comprising determining a nominal closing point value for the bleed-off valve on the modulation characteristic curve, the nominal closing point value is a value of the engine speed, the gas turbine engine measured value is less than the nominal closing point value.