# US 8,769,962 B2 · Multi-circuit buffer system for a gas turbine engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,769,962 B2 - Document ID: US8769962B2 - Status: Granted - Kind: B2 - Application number: 13/362,349 - Filed: 2012-01-31 - Published: 2013-08-01 - Granted: 2014-07-08 - Earliest claimed: 2012-01-31 - Assignees: United Technologies Corporation - Applicants: Jorn A. Glahn; William K. Ackermann; Clifton J. Crawley; Philip S. Stripinis - Inventors: Jorn A. Glahn; William K. Ackermann; Clifton J. Crawley; Philip S. Stripinis - Web page: https://patentgrep.com/patent/US8769962B2 ## CPC - F02C 6/08: the gas being bled from the gas-turbine compressor - F01D 25/18: Lubricating arrangements (of machines or engines in general F01M) - F01D 25/183: {Sealing means} - F02C 7/12: Cooling of plants (of component parts, see the relevant subclasses, e.g. F01D; cooling of engines in general F01P) - F02C 7/14: of fluids in the plant {, e.g. lubricant or fuel (F02C7/185 takes precedence)} - F05D 2260/601: using an ejector or a jet pump - 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) - 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 includes a buffer system that includes a first circuit and a second circuit. The first circuit can communicate a first buffer supply air to a first portion of the gas turbine engine and the second circuit can communicate a second buffer supply air to a second portion of the gas turbine engine. ## Claims ### Claim 1 A gas turbine engine, comprising: a buffer system that includes a first circuit that communicates a first buffer supply air to a first portion of the gas turbine engine and a second circuit that communicates a second buffer supply air to a second portion of the gas turbine engine, wherein said first buffer supply air and said second buffer supply air address different pressure requirements of separate bearing compartments to contain lubricant within said separate bearing compartments; wherein said first buffer supply air and said second buffer supply air do not share a common source of air within the engine; wherein said first circuit includes a first bleed air supply, a second bleed air supply and a valve; and wherein said second circuit includes a first bleed air supply, a second bleed air supply, a valve and a conditioning device. ### Claim 2 (depends on 1) The gas turbine engine as recited in claim 1, wherein said first portion of the gas turbine engine includes a component subject to low pressure requirements and said second portion of the gas turbine engine includes a component subject to high pressure requirements. ### Claim 3 (depends on 1) The gas turbine engine as recited in claim 1, wherein said first portion and said second portion are separate bearing compartments of the gas turbine engine. ### Claim 4 (depends on 1) The gas turbine engine as recited in claim 1, comprising at least one controller in communication with each of said first circuit and said second circuit. ### Claim 5 (depends on 1) The gas turbine engine as recited in claim 1, wherein said first buffer supply air addresses low pressure requirements in at least one of a front bearing compartment and a rear bearing compartment, and said second buffer supply air addresses high pressure requirements in a mid-engine bearing compartment. ### Claim 6 A gas turbine engine, comprising: a compressor section; a combustor in fluid communication with said compressor section; a turbine section in fluid communication with said combustor; a buffer system including a first circuit that supplies a first buffer supply air and a second circuit that supplies a second buffer supply air; wherein said first buffer supply air and said second buffer supply air do not share a common source of air within the engine, wherein said first circuit addresses a component subject to a first pressure requirement of the gas turbine engine with said first buffer supply air to contain lubricant within said component; and wherein said second circuit addresses a second component subject to a second pressure requirement of the gas turbine engine that is different from said first pressure requirement with said second buffer supply air to contain lubricant within said second component; wherein said first circuit includes a first bleed air supply, a second bleed air supply and a valve; and wherein said second circuit includes a first bleed air supply, a second bleed air supply, a valve and a conditioning device. ### Claim 7 (depends on 6) The gas turbine engine as recited in claim 6, wherein the gas turbine engine is a high bypass geared aircraft engine having a bypass ratio of greater than about six (6). ### Claim 8 (depends on 6) The gas turbine engine as recited in claim 6, wherein the gas turbine engine includes a low Fan Pressure Ratio of less than about 1.45. ### Claim 9 (depends on 6) The gas turbine engine as recited in claim 6, wherein said first circuit provides a first pressure to the component subject to the first pressure requirement and said second circuit provides a second pressure to the second component subject to the second pressure requirement. ### Claim 10 (depends on 9) The gas turbine engine as recited in claim 9, wherein the component subject to the first pressure requirement and the second component subject to the second pressure requirement are separate bearing compartments of the gas turbine engine. ### Claim 11 (depends on 6) The gas turbine engine as recited in claim 6, comprising at least one controller in communication with each of said first circuit and said second circuit for governing augmentation of buffer supply air for at least one of the first circuit and the second circuit. ### Claim 12 (depends on 6) The gas turbine engine as recited in claim 6, wherein said first buffer supply air and said second buffer supply air maintain a minimum pressure delta across the component subject to the first pressure requirement and the second component subject to the second pressure requirement. ### Claim 13 (depends on 11) The gas turbine engine as recited in claim 11, comprising a sensor that detects a power condition of the gas turbine engine and communicates a signal to said controller to command modulation of a valve between the first bleed air supply and the second bleed air supply of at least one of said first circuit and said second circuit. ### Claim 14 A method of cooling a portion of a gas turbine engine, comprising: addressing a component subject to a first pressure requirement of the gas turbine engine with a first buffer supply air from a first circuit of a buffer system to contain lubricant within the component; and addressing a second component subject to a second pressure requirement of the gas turbine engine that is different from the first pressure requirement with a second buffer supply air from a second circuit of the buffer system to contain lubricant within the second component, the first buffer supply air and the second buffer supply air do not share a common source of air within the engine; wherein said first circuit includes a first bleed air supply, a second bleed air supply and a valve; and wherein said second circuit includes a first bleed air supply, a second bleed air supply, a valve and a conditioning device. ### Claim 15 (depends on 14) The method as recited in claim 14, wherein the second component subject to the second pressure requirement is located separate from the component subject to the first pressure requirement. ### Claim 16 (depends on 14) The method as recited in claim 14, comprising the step of: identifying a power condition of the gas turbine engine prior to the steps of addressing. ### Claim 17 (depends on 16) The method as recited in claim 16, comprising the step of: communicating low pressure bleed air supplies as the first buffer air supply and the second buffer air supply in response to identifying a high power condition; and communicating high pressure bleed air supplies as the first buffer air supply and the second buffer air supply in response to identifying a low power condition. ### Claim 18 (depends on 14) The method as recited in claim 14, comprising the step of: cooling the second buffer supply air prior to the step of addressing the second component subject to the second pressure requirement. ### Claim 19 (depends on 14) The method as recited in claim 14, including augmenting one of the first buffer air supply and the second buffer air supply with an ejector. ### Claim 20 (depends on 17) The method as recited in claim 17, wherein the high power condition includes one of a takeoff condition, a climb condition and cruise condition. ### Claim 21 (depends on 17) The method as recited in claim 17, wherein the low power condition includes one of a ground operation condition, a ground idle condition and a flight idle condition. ### Claim 22 A gas turbine engine, comprising: a buffer system that includes a first circuit that communicates a first buffer supply air to a first portion of the gas turbine engine and a second circuit that communicates a second buffer supply air to a second portion of the gas turbine engine, wherein said first buffer supply air and said second buffer supply air address different pressure requirements of separate bearing compartments to contain lubricant within said separate bearing compartments; and wherein each of said first circuit and said second circuit include at least two bleed air supplies, and said at least two bleed air supplies of said first circuit are completely separate from said at least two bleed air supplies of said second circuit.