# US 11,905,841 B1 · Buffer air method and system for a bearing compartment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,905,841 B1 - Document ID: US11905841B1 - Status: Granted - Kind: B1 - Application number: 18/105,632 - Filed: 2023-02-03 - Granted: 2024-02-20 - Earliest claimed: 2023-02-03 - Assignees: Rtx Corporation - Applicants: Raytheon Technologies Corporation - Inventors: Jorn A. Glahn; Collin P. Fitzgerald; Gregory M. Dooley - Web page: https://patentgrep.com/patent/US11905841B1 ## CPC - F01D 25/22: using working-fluid or other gaseous fluid as lubricant - F01D 11/04: using sealing fluid, e.g. steam - F01D 25/125: {of bearings} - F01D 25/16: Arrangement of bearings; Supporting or mounting bearings in casings (bearings per se F16C) - F01D 25/183: {Sealing means} - F02C 6/08: the gas being bled from the gas-turbine compressor - F02C 7/06: Arrangements of bearings (bearings F16C); Lubricating ({of turbo machines F01D25/18; of machines or} engines in general F01M) - F05D 2220/32: in gas turbines - F05D 2240/50: Bearings - F05D 2240/55: Seals - F05D 2260/60: Fluid transfer - F05D 2260/605: Venting into the ambient atmosphere or the like - 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) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A method of operation is provided during which buffer air flows into a buffer cavity in a turbine engine. The buffer cavity surrounds a bearing compartment in the turbine engine. Leakage air flows across a buffer seal device in the turbine engine. The buffer air and the leakage air are combined to provide combined air. The combined air is vented to a pressure sink such that: a pressure of the buffer air within the buffer cavity is maintained at or below a maximum buffer air threshold during operation of the turbine engine; and a flowrate of the leakage air across the buffer seal device is maintained at or above a minimum leakage air threshold during the operation of the turbine engine. ## Claims ### Claim 1 A method of operation, comprising: flowing buffer air into a buffer cavity in a turbine engine, the buffer cavity surrounding a bearing compartment in the turbine engine; flowing leakage air across a buffer seal device in the turbine engine; combining the buffer air and the leakage air to provide combined air; and venting the combined air to a pressure sink such that a pressure of the buffer air within the buffer cavity is maintained at or below a maximum buffer air threshold during operation of the turbine engine; and a flowrate of the leakage air across the buffer seal device is maintained at or above a minimum leakage air threshold during the operation of the turbine engine. ### Claim 2 (depends on 1) The method of claim 1, wherein the combined air is vented to the pressure sink through a valve. ### Claim 3 (depends on 2) The method of claim 2, wherein the valve is configured as a discrete position valve. ### Claim 4 (depends on 2) The method of claim 2, wherein the valve is configured as a variable position valve. ### Claim 5 (depends on 2) The method of claim 2, further comprising controlling operation of the valve using an electronic control system for the turbine engine. ### Claim 6 (depends on 2) The method of claim 2, further comprising: monitoring an operational parameter of the turbine engine; and controlling operation of the valve based on the operational parameter. ### Claim 7 (depends on 1) The method of claim 1, wherein at least some of the combined air is vented to the pressure sink throughout the operation of the turbine engine. ### Claim 8 (depends on 1) The method of claim 1, wherein the leakage air flows across the buffer seal device from a high pressure cavity in the turbine engine to a low pressure cavity in the turbine engine; the buffer air is combined with the leakage air in the low pressure cavity; the low pressure cavity surrounds the buffer cavity; and the high pressure cavity surrounds the low pressure cavity. ### Claim 9 (depends on 8) The method of claim 8, wherein a low pressure cavity wall in the turbine engine includes a sidewall and an endwall; the sidewall is radially between and forms the low pressure cavity and the high pressure cavity; the endwall projects radially inward from the sidewall, and the endwall is axially between and forms the low pressure cavity and the high pressure cavity; and the buffer seal device seals a gap between the endwall and a rotating structure in the turbine engine. ### Claim 10 (depends on 8) The method of claim 8, wherein at least one of the buffer cavity is radially adjacent the bearing compartment; the low pressure cavity is radially adjacent the buffer cavity; or the high pressure cavity is radially adjacent the low pressure cavity. ### Claim 11 (depends on 8) The method of claim 8, wherein at least one of the buffer cavity axially overlaps the bearing compartment; the low pressure cavity axially overlaps the buffer cavity; or the high pressure cavity axially overlaps the low pressure cavity. ### Claim 12 (depends on 8) The method of claim 8, wherein a diffuser plenum in the turbine engine surrounds the high pressure cavity; and a combustor in the turbine engine is disposed within the diffuser plenum. ### Claim 13 (depends on 8) The method of claim 8, wherein the high pressure cavity is radially inboard of a core flowpath within the turbine engine. ### Claim 14 (depends on 1) The method of claim 1, wherein a bearing compartment wall in the turbine engine includes a sidewall radially between and forming the bearing compartment and the buffer cavity; a first endwall projecting radially inward from the sidewall, the first endwall axially between and forming the bearing compartment and the buffer cavity; and a second endwall projecting radially inward from the sidewall, the second endwall axially between and forming the bearing compartment and the buffer cavity. ### Claim 15 (depends on 1) The method of claim 1, wherein a bearing compartment wall in the turbine engine is disposed between and forms the bearing compartment and the buffer cavity; each of a plurality of bearing seal devices in the turbine engine seal a respective gap between the bearing compartment wall and a rotating structure in the turbine engine; and the bearing compartment is disposed axially between the plurality of bearing seal devices. ### Claim 16 (depends on 1) The method of claim 1, wherein both the buffer cavity and the bearing compartment are formed by a stationary structure and a rotating structure in the turbine engine. ### Claim 17 An assembly for a turbine engine, comprising: a stationary structure forming a bearing compartment, a buffer cavity, a low pressure cavity and a high pressure cavity, the buffer cavity outboard of the bearing compartment, the low pressure cavity outboard of the buffer cavity, and the high pressure cavity outboard of the low pressure cavity; a vent line fluidly coupled with the low pressure cavity, the low pressure cavity configured to direct leakage air from the high pressure cavity and buffer air from the buffer cavity into the vent line as low pressure air; a valve fluidly coupled with and downstream of the vent line; and a control system configured to signal the valve to control venting of the low pressure air from the low pressure cavity through the vent line such that a pressure of the buffer air within the buffer cavity is maintained at or below a maximum buffer air threshold; and a flowrate of the leakage air across the buffer seal device is maintained at or above a minimum leakage air threshold. ### Claim 18 (depends on 17) The assembly of claim 17, wherein the valve is configured as one of a two-position valve and a variable position valve.