# US 9,038,801 B2 · Clutch with pressure sustaining system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,038,801 B2 - Document ID: US9038801B2 - Status: Granted - Kind: B2 - Application number: 13/524,538 - Filed: 2012-06-15 - Published: 2013-12-19 - Granted: 2015-05-26 - Earliest claimed: 2012-06-15 - Assignees: Hamilton Sundstrand Corporation - Applicants: Dean A. Norem; Alex Rak; Timothy P. Walgren; Raymond N. Weyl; Ricky D. Reimers; Charles E. Long - Inventors: Dean A. Norem; Alex Rak; Timothy P. Walgren; Raymond N. Weyl; Ricky D. Reimers; Charles E. Long - Web page: https://patentgrep.com/patent/US9038801B2 ## CPC - F16D 25/02: with means for actuating or keeping engaged by a force derived at least partially from one of the shafts to be connected - F16D 25/0638: with more than two discs, e.g. multiple lamellae - B64D 35/00: Transmitting power from power plants to propellers or rotors; Arrangements of transmissions - F16D 2048/0218: {Reservoirs for clutch control systems; Details thereof} - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT ## Abstract An assembly includes an output shaft, an input shaft with an internal reservoir, and a clutch. The clutch is adapted to selectively engage and couple the input shaft to the output shaft. The clutch has a pressure chamber that communicates with the reservoir of the input shaft. The reservoir has a sufficient volume to provide the pressure chamber with a fluid pressure adequate to maintain engagement of the clutch during an interruption of a fluid supply to the input shaft and clutch. ## Claims ### Claim 1 An assembly comprising: an output shaft; an input shaft having an internal reservoir; a balance pressure chamber having a first fluid inner radius which is fixed during operation; and a clutch adapted to selectively engage and couple the input shaft to the output shaft, the clutch comprising: an actuation pressure chamber that communicates with the reservoir of the input shaft, wherein the actuation pressure chamber has a second fluid inner radius which is variable during operation; and one or more passages that communicate fluid generally radially outward from the reservoir to the actuation pressure chamber, wherein the one or more passages include one or more axial bleed orifices connecting the one or more passages to a plenum axially overlapping with a plurality of clutch plates and radially between the clutch plates and the reservoir; and wherein in operation during an interruption of a fluid supply to the input shaft the second fluid inner radius is located radially inward of the first fluid inner radius such that during the interruption of the fluid supply to the input shaft a centrifugal head pressure of the actuation pressure chamber is greater than a centrifugal head pressure of the balance pressure chamber, and wherein the reservoir has a sufficient volume to maintain the second fluid inner radius radially inward of the first fluid inner radius such that the actuation pressure chamber is provided with a fluid pressure adequate to maintain engagement of the clutch-during an interruption of a fluid supply to the input shaft. ### Claim 2 (depends on 1) The assembly of claim 1, wherein the one or more bleed orifices are sized to provide the actuation pressure chamber with a fluid pressure adequate to maintain engagement of the clutch during the interruption of fluid to the input shaft and clutch. ### Claim 3 (depends on 1) The assembly of claim 1, wherein one or more radial orifices connect the plenum to the reservoir. ### Claim 4 (depends on 1) The assembly of claim 1, wherein a duration of interruption is less than about 6 seconds. ### Claim 5 (depends on 1) The assembly of claim 1, wherein the clutch comprises a rotating transfer coupling that extends from and has portions integral with the input shaft. ### Claim 6 (depends on 1) The assembly of claim 1, wherein the clutch includes a piston that linearly moves to vary a size of the actuation pressure chamber in response to changes in fluid pressure. ### Claim 7 (depends on 6) The assembly of claim 6, wherein the piston acts as a pressure actuator to contact the clutch plates together to transfer torque from the input shaft to the output shaft. ### Claim 8 An aircraft comprising: an airframe; a drive system supported by the airframe, wherein the drive system comprises: an output shaft; an input shaft having an internal reservoir; a balance pressure chamber having a first fluid inner radius which is fixed during operation; and a clutch adapted to selectively engage and couple the input shaft to the output shaft, the clutch comprising: an actuation pressure chamber that communicates with the reservoir of the input shaft, wherein the actuation pressure chamber has a second fluid inner radius which is variable during operation; and one or more passages that communicate fluid generally radially outward from the reservoir to the actuation pressure chamber, wherein the one or more passages include one or more axial bleed orifices connecting the one or more passages to a plenum axially overlapping with a plurality of clutch plates and radially between the clutch plates and the reservoir; and wherein in operation during an interruption of a fluid supply to the input shaft the second fluid inner radius is located radially inward of the first fluid inner radius such that during the interruption of the fluid supply to the input shaft a centrifugal head pressure of the actuation pressure chamber is greater than a centrifugal head pressure of the balance pressure chamber, and wherein the reservoir has a sufficient volume to maintain the second fluid inner radius radially inward of the first fluid inner radius such that the actuation pressure chamber is provided with a fluid pressure adequate to maintain engagement of the clutch during an interruption of a fluid supply to the input shaft. ### Claim 9 (depends on 8) The aircraft of claim 8, wherein the clutch includes one or more passages that communicate fluid from the reservoir to the actuation pressure chamber. ### Claim 10 (depends on 9) The aircraft of claim 9, wherein the one or more passages include one or more bleed orifices, and wherein the one or more bleed orifices are sized to provide the actuation pressure chamber with a fluid pressure adequate to maintain engagement of the clutch during an interruption of fluid to the input shaft and clutch. ### Claim 11 (depends on 10) The aircraft of claim 10, wherein one or more radial orifices connect the plenum to the reservoir. ### Claim 12 (depends on 8) The aircraft of claim 8, wherein the clutch comprises a rotating transfer coupling that extends from and has portions integral with the input shaft. ### Claim 13 (depends on 8) The aircraft of claim 8, wherein the aircraft comprises a high speed vertical takeoff and landing (VTOL) rotary-wing aircraft. ### Claim 14 (depends on 8) The aircraft of claim 8, wherein the drive system comprises a secondary thrust system. ### Claim 15 (depends on 8) The aircraft of claim 8, wherein the fluid supplied to the input shaft and clutch comes from a lubrication system of the aircraft. ### Claim 16 An assembly comprising: an output shaft; an input shaft having an internal reservoir; a balance pressure chamber having a first fluid inner radius which is fixed during operation; and a clutch adapted to selectively engage and couple the input shaft to the output shaft, the clutch having an actuation pressure chamber that communicates with the reservoir of the input shaft via one or more passages, wherein the one or more passages include one or more axial bleed orifices in fluid communication with a plenum axially overlapping with a plurality of clutch plates and radially between the clutch plates and the reservoir, wherein the actuation pressure chamber has a second fluid inner radius which is variable during operation, wherein in operation during an interruption of a fluid supply to the input shaft the second fluid inner radius is located radially inward of the first fluid inner radius, and wherein the one or more bleed orifices and the reservoir of the shaft are sized to maintain the second fluid inner radius radially inward of the first fluid inner radius such that the actuation pressure chamber has a fluid pressure adequate to maintain engagement of the clutch during the interruption of a fluid supply to the input shaft and clutch. ### Claim 17 (depends on 16) The assembly of claim 16, wherein the clutch comprises a rotating transfer coupling that extends from and has portions integral with the input shaft. ### Claim 18 (depends on 16) The assembly of claim 16, wherein the clutch includes piston slides to vary a size of the actuation pressure chamber in response to changes in fluid pressure. ### Claim 19 (depends on 18) The assembly of claim 18, wherein the piston acts as a pressure actuator to contact the clutch plates together to transfer torque from the input shaft to the output shaft. ### Claim 20 (depends on 1) The assembly of claim 1, wherein the balance pressure chamber is circumferentially open at an inner radial end.