# US 11,441,605 B1 · Dual-film damper > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,441,605 B1 - Document ID: US11441605B1 - Status: Granted - Kind: B1 - Application number: 17/188,249 - Filed: 2021-03-01 - Published: 2022-09-01 - Granted: 2022-09-13 - Earliest claimed: 2021-03-01 - Assignees: Pratt & Whitney Canada Corp. - Applicants: Pratt & Whitney Canada Corp. - Inventors: Mert Cevik; Philip A. Varney; Robert J. Morris; David Beamish - Web page: https://patentgrep.com/patent/US11441605B1 ## CPC - F16C 27/045: {with a fluid film, e.g. squeeze film damping} - F01D 25/164: {Flexible supports; Vibration damping means associated with the bearing} - F16F 15/0237: {involving squeeze-film damping} - F16C 19/06: with a single row or balls - F16C 2360/23: Gas turbine engines - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION ## Abstract A dual-film damper has a housing defining an annular damper fluidly connected to a source of pressurized oil. First and second damper rings are coaxially nested within the damper cavity. A first set of spacers allows for the formation of a first oil film annulus between the first and second damper rings. A second set of spacers allows for the formation of a second oil film annulus between the second damper ring and the housing. The first and second oil film annuli have a thickness-to-length ratio (T/L) selected to provide a desired damping capacity. ## Claims ### Claim 1 A dual-film damper in a gas turbine engine, comprising: a housing circumscribing an annular damper cavity around an axis and having an oil inlet connectable in flow communication with a source of pressurized oil; a first and a second damper ring coaxially nested within the annular damper cavity; a first pair of axially spaced-apart spacers positioned radially between the first and second damper rings, the first pair of axially spaced-apart spacers creating a first oil film annulus between the first and second damper rings; and a second pair of axially spaced-apart spacers radially between the second damper ring and the housing, the second set of spacers creating a second oil film annulus between the second damper ring and the housing, the second oil film annulus surrounding the first oil film annulus; each of the first and second oil film annuli having a thickness-to-length ratio (T/L) ranging from 0.0025 to 0.03. ### Claim 2 (depends on 1) The dual-film damper according to claim 1, wherein the first oil film annulus has a thickness T1, wherein the second oil film annulus has a thickness T2, and wherein T1/T2 is between 0.5 and 5. ### Claim 3 (depends on 2) The dual-film damper according to claim 2, wherein the thickness T1 of the first oil film annulus ranges from 5 mils (0.127 mm) to 30 mils (0.762 mm), and wherein the thickness T2 of the second film annulus ranges from 2.5 mils (0.0635 mm) to 45 mils (1.143 mm). ### Claim 4 (depends on 2) The dual-film damper according to claim 2, wherein the first and second oil film annuli have the same length (L). ### Claim 5 (depends on 1) The dual-film damper according to claim 1, wherein the thickness-to-length ratio (T/L) ranges from 0.0053 to 0.025. ### Claim 6 (depends on 1) The dual-film damper according to claim 1, wherein the first and second oil film annuli have the same thickness-to-length ratio (T/L). ### Claim 7 (depends on 1) The dual-film damper according to claim 1, wherein the first damper ring is an outer race of a bearing. ### Claim 8 (depends on 1) The dual-film damper according to claim 1, wherein the first and second oil film annuli have a length L ranging from 1000 mils (25.4 mm) to 1500 mils (38.1 mm) mm, and wherein the first and second oil film annuli have a thickness T ranging from 8 mils (0.203 mm) mm to 25 mils (0.635 mm). ### Claim 9 (depends on 1) The dual-film damper according to claim 1, wherein the first and second oil film annuli have a length L range from 1000 mils (25.4 mm) mm to 2000 mils (50.8 mm), wherein the first oil film annulus has a thickness T1 ranging from 5 mils (0.127 mm) to 30 mils (0.762 mm) and wherein the second oil film annulus has a thickness T2 ranging from 2.5 mils (0.063 mm) to 45 mils (1.143 mm). ### Claim 10 A dual-film damper for damping radial movement of a rotary shaft relative to a rotation axis, the dual-film damper comprising: a housing defining an oil damper cavity around the rotation axis; at most two coaxially nested damper rings including first and second damper rings disposed in the oil damper cavity; a first annulus located radially between the first and second damper rings; a second annulus located radially between the second damper ring and the housing, the second annulus encircling the first annulus; and a first and a second pair of axially spaced-apart piston rings projecting respectively radially across the first annulus and the second annulus, the first and second pairs of axially spaced-apart piston rings defining a thickness T and a length L of the first annulus and the second annulus, respectively; wherein a thickness-to-length ratio (T/L) ranges from 0.0053 to 0.025. ### Claim 11 (depends on 10) The dual-film damper according to claim 10, wherein the length L ranges from 1000 mils (25.4 mm) to 1500 mils (38.1 mm), and wherein the thickness T ranges from 8 mils (0.203 mm) to 25 mils (0.635 mm). ### Claim 12 (depends on 11) The dual-film damper according to claim 11, wherein the first annulus and the second annulus have the same length L and the same thickness T. ### Claim 13 (depends on 12) The dual-film damper according to claim 12, wherein the thickness T is equal to 16 mils (0.406 mm). ### Claim 14 (depends on 10) The dual-film damper according to claim 10, wherein the first damper ring is an outer race of a bearing. ### Claim 15 A dual-film damper for damping radial movement of a rotary shaft relative to a rotation axis, the dual-film damper comprising: a housing defining an oil damper cavity around the rotation axis; at most two damper rings including first and second damper rings disposed in the oil damper cavity, the second damper ring encircling the first damper ring; a first oil film annulus located radially between the first and second damper rings; a second oil film annulus located radially between the second damper ring and the housing; and a first and a second pair of spacer rings respectively projecting radially across the first oil film annulus and the second oil film annulus, the first and second pairs of spacer rings respectively defining a thickness T and a length L of the first oil film annulus and the second oil film annulus, wherein the length L ranges from 1000 mils (25.4 mm) to 2000 mils (50.8 mm), wherein the thickness T of the first oil film annulus ranges from 5 mils (0.127 mm) to 30 mils (0.762 mm), and wherein the thickness T of the second oil film annulus ranges from 2.5 mils (0.051 mm) to 45 mils (1.143 mm). ### Claim 16 (depends on 15) The dual-film damper according to claim 15, wherein the first oil film annulus has a first thickness T1, the second oil film annulus has a second thickness T2, and wherein T1/T2 is between 0.5 and 5. ### Claim 17 (depends on 15) The dual-film damper according to claim 15, wherein the first and second oil film annuli have a different thickness-to-length ratio (T/L). ### Claim 18 (depends on 15) The dual-film damper according to claim 15, wherein the first and second oil film annuli have the same length L. ### Claim 19 (depends on 15) The dual-film damper according to claim 15, wherein the first damper ring is an outer race of a bearing. ### Claim 20 (depends on 15) The dual-film damper according to claim 15, wherein the thickness T of the first oil film annulus is equal to the thickness of the second oil film annulus.