# US 12,759,694 B2 · Methods and apparatus to control propeller pitch in dual acting propellers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,759,694 B2 - Document ID: US12759694B2 - Status: Granted - Kind: B2 - Application number: 18/525,315 - Filed: 2023-11-30 - Published: 2024-10-31 - Granted: 2026-10-13 - Earliest claimed: 2023-04-28 - Assignees: GE Avio S.r.l. - Applicants: Ge Avio S.R.L - Inventors: Diego Di Leo; Giuseppe Cervelli; Paolo Altamura - Web page: https://patentgrep.com/patent/US12759694B2 ## CPC - B64C 11/385: {comprising feathering, braking or stopping systems} - B64C: AEROPLANES; HELICOPTERS ## Abstract Methods, apparatus, systems, and articles of manufacture are disclosed to control propeller pitch in dual acting propellers. An example propeller control system comprising: a piston including a piston rod; a first valve connected to the piston rod via a first piston line and a second piston line, wherein the first valve selectively allows, based on an input signal, hydraulic fluid to transfer to the piston via the first piston line and the second piston line, wherein the first valve is a three-state valve; and an independent valve connected to the piston rod via a third piston line, wherein the independent valve selectively allows, based on an input signal, hydraulic fluid to transfer to the piston via the third piston line and wherein the independent valve operates independently of the first valve. ## Claims ### Claim 1 A propeller control system comprising: a coarse chamber; a fine chamber; a piston separating the fine chamber and the coarse chamber, the piston including a piston rod; and a first valve connected to the piston rod via a first piston line and a second piston line, wherein the first valve is configured to selectively allow hydraulic fluid to transfer to at least one of (a) the coarse chamber through the piston via the first piston line or (b) the fine chamber through the piston via the second piston line, wherein the first valve is a three-state valve, wherein, when the first valve is in a fine line blockage state, the first valve is configured to block the hydraulic fluid from the fine chamber from transferring to a drain and allow the hydraulic fluid to transfer to the coarse chamber. ### Claim 2 (depends on 1) The propeller control system of claim 1, further includes a propeller dome having an interior to house the piston wherein the piston defines a first side and a second side within the interior and wherein the first side defines the coarse chamber and the second side defines the fine chamber, and wherein the coarse chamber is larger than the fine chamber, and the fine chamber is separated from the coarse chamber with a seal. ### Claim 3 (depends on 1) The propeller control system of claim 1, wherein the first valve has the fine line blockage state, the fine line blockage state includes: a first valve line connected to the first piston line of the piston rod via a first port to transfer hydraulic fluid to a first side of the piston; and a second valve line disconnected from the second piston line of the piston rod. ### Claim 4 (depends on 1) The propeller control system of claim 1, wherein the first valve has a nominal state, the nominal state includes: a second valve line connected to the first piston line of the piston rod via a second port to transfer hydraulic fluid to a first side of the piston; and a third valve line connected to the second piston line of the piston rod via a third port to transfer hydraulic fluid to a second side of the piston. ### Claim 5 (depends on 1) The propeller control system of claim 1, wherein the first valve has a feather state, the feather state includes: a first valve line connected to the first piston line of the piston rod via a first port to transfer hydraulic fluid to a first side of the piston; and the second piston line of the piston connected to the drain via a third port to transfer hydraulic fluid from a second side of the piston. ### Claim 6 (depends on 1) The propeller control system of claim 1, further including a second valve configured to selectively allow hydraulic fluid transfer to the first valve. ### Claim 7 (depends on 1) The propeller control system of claim 1, further including an independent valve connected to the piston rod via a third piston line, wherein the independent valve is configured to selectively allow the hydraulic fluid to transfer to the piston via the third piston line and wherein the independent valve operates independently of the first valve, wherein the independent valve is connected to the third piston line of the piston rod to transfer hydraulic fluid, wherein the hydraulic fluid is transferred with respect to a pitch lock mechanism to prevent a plurality of blades from moving towards fine direction. ### Claim 8 (depends on 1) The propeller control system of claim 1, wherein a controller sends a signal to the first valve to operate in the fine line blockage state, a nominal state, or a feather state. ### Claim 9 A variable pitch propeller assembly comprising: a plurality of blades rotatable about an axial direction; a coarse chamber; a fine chamber; a piston separating the fine chamber and the coarse chamber, the piston including a piston rod; and a propeller control system including a first valve to selectively, based on an input signal, transfer hydraulic fluid to the coarse chamber via a first piston line of the piston rod and block the hydraulic fluid from the fine chamber from transferring to a drain via a second piston line of the piston rod, wherein the first valve is a three-state valve. ### Claim 10 (depends on 9) The variable pitch propeller assembly of claim 9, wherein the first valve has a fine line blockage state, the fine line blockage state includes: a first valve line connected to the first piston line of the piston rod via a first port to transfer hydraulic fluid to a first side of the piston; and a second valve line disconnected from the second piston line of the piston rod. ### Claim 11 (depends on 9) The variable pitch propeller assembly of claim 9, wherein the first valve has a nominal state, the nominal state includes: a second valve line connected to the first piston line of the piston rod via a second port to transfer hydraulic fluid to a first side of the piston; and a third valve line connected to the second piston line of the piston rod via a third port to transfer hydraulic fluid to a second side of the piston. ### Claim 12 (depends on 9) The variable pitch propeller assembly of claim 9, wherein the first valve has a feather state, the feather state includes: a first valve line connected to the first piston line of the piston rod via a first port to transfer hydraulic fluid to a first side of the piston; and the second piston line of the piston connected to the drain via a third port to transfer hydraulic fluid from a second side of the piston. ### Claim 13 (depends on 9) The variable pitch propeller assembly of claim 9, further including a second valve to selectively allow, based on a signal, hydraulic fluid transfer to the first valve. ### Claim 14 (depends on 9) The variable pitch propeller assembly of claim 9, further includes a propeller dome to house the piston wherein a first side of the piston defines the coarse chamber and a second side of the piston defines the fine chamber, wherein the coarse chamber is larger than the fine chamber, and the fine chamber is separated from the coarse chamber with a seal. ### Claim 15 (depends on 9) The variable pitch propeller assembly of claim 9, wherein the propeller control system further includes an independent valve to transfer hydraulic fluid to a third line of the piston rod, wherein the independent valve operates independently of the first valve, wherein the independent valve transfers hydraulic fluid with respect to the third line of the piston rod to a pitch lock mechanism to prevent the plurality of blades from moving towards fine direction. ### Claim 16 (depends on 9) The variable pitch propeller assembly of claim 9, wherein a controller sends a signal to the first valve to operate in a fine line blockage state, a nominal state, or a feather state.