Aircraft engine fuel system
First Claim
1. A fuel system for use in an aircraft engine, the fuel system comprising:
- a fuel pump for pressurizing fuel from a fuel supply, a plurality of fuel nozzles arranged in a combustion chamber, a fuel metering unit for controlling the flow of fuel from the fuel pump to the fuel nozzles,a fuel manifold fluidically connecting the fuel metering unit to the fuel nozzles, andan ecology valve fluidically connected to the fuel manifold, the ecology valve having a reservoir for temporary storage of fuel, and reservoir control means for suctioning sufficient fuel into the reservoir to prevent coking of the nozzles upon engine shutdown for temporary storage and return of the temporarily stored fuel for combustion in the next engine operating cycle.
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Accused Products
Abstract
A fuel system for a gas turbine aircraft engine including a ecology valve and a flow divider valve, both of simple and compact construction. The ecology valve is connected to the fuel manifolds supplied by the splitter valve, and serves to suction fuel from the fuel manifolds upon engine shutdown. The fuel is temporarily stored in reservoirs in the ecology valve and upon the next engine operating cycle, is returned to the manifold so that it can be burned. The splitter valve is of simplified light-weight construction and includes a single piston operated in two regions, a first for modulating primary and second flow depending on fuel pressure, and a second region for providing a fixed, port geometry determined split between the primary and secondary.
123 Citations
20 Claims
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1. A fuel system for use in an aircraft engine, the fuel system comprising:
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a fuel pump for pressurizing fuel from a fuel supply, a plurality of fuel nozzles arranged in a combustion chamber, a fuel metering unit for controlling the flow of fuel from the fuel pump to the fuel nozzles, a fuel manifold fluidically connecting the fuel metering unit to the fuel nozzles, and an ecology valve fluidically connected to the fuel manifold, the ecology valve having a reservoir for temporary storage of fuel, and reservoir control means for suctioning sufficient fuel into the reservoir to prevent coking of the nozzles upon engine shutdown for temporary storage and return of the temporarily stored fuel for combustion in the next engine operating cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An ecology valve for use in an aircraft engine fuel system, the fuel system comprising a fuel pump for pressurizing the fuel in a fuel supply, a fuel metering unit for modulating the fuel flow rate from the fuel supply to a primary and secondary set of fuel nozzles, and a primary and secondary fuel manifold fluidically connecting the fuel metering unit to the primary and secondary fuel nozzles, respectively, the ecology valve comprising:
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a valve body; a pressure actuated piston slidably disposed within the valve body and movable between an unloaded position corresponding to engine shut-down and a loaded position corresponding to engine operation, the piston having a pressure face on one side and an annular skirt on the other side; spring means for biasing the piston toward the unloaded position; the valve body cooperating with the skirt portion of the piston to create a first and second storage reservoir separated by the skirt portion and connected to the primary and secondary manifolds, respectively, translation of said piston sensing to increase or decrease the size of the respective reservoirs for accepting fuel from or returning fuel to the respective manifolds; the valve body and pressure face of the piston creating a pressure chamber fluidically connected to the fuel metering unit for responding to the pressure level in the fuel supply; and whereby movement of the piston from the loaded position to the unloaded position during engine shut-down suctions fuel from the primary and secondary manifolds to the first and second storage chambers, respectively, and movement of the piston from the unloaded position to the loaded position during engine start-up drives fuel from the first and second storage chambers to the primary and secondary fuel manifolds, respectively.
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12. A flow divider valve for use in an aircraft engine fuel system, the fuel system comprising a fuel pump for pressurizing fuel from a fuel supply, a primary and a secondary set of fuel nozzles arranged in a combustion chamber, a fuel metering unit for controlling the flow of fuel from the fuel pump to the fuel nozzles, primary and secondary fuel manifolds fluidically connecting the flow divider valve to the primary and secondary fuel nozzles, respectively, and a fuel line fluidically connecting the fuel metering unit to the flow divider valve, the flow divider valve comprising, in combination:
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a flow divider valve body and a ported piston mounted for translation therein; means biasing the ported piston to a quiescent condition in which flow to the primary and secondary manifolds is shut off; the body and ported piston establishing two operating regions for the valve; ports in the body and piston effective with the piston in the first region for modulating primary flow as a function of inlet fuel pressure; a relief valve for bypassing the piston for diverting a portion of the modulated primary flow to the secondary as a function of the pressure differential in the primary and secondary manifolds; means activated by continued piston travel from the first toward the second regions for sharply translating the piston to a final operating position in the second region; and ports in the body and piston effective with the piston in the second region for providing a fixed unmodulated split of flow through the divider valve to the primary and second manifolds. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method for ecologically regulating fuel flow in an aircraft engine fuel system, the fuel system comprising a fuel pump for pressurizing fuel from a fuel supply, a plurality of fuel nozzles arranged in a combustion chamber, a fuel metering unit for controlling the flow of fuel from the fuel pump to the fuel nozzles, and a fuel manifold fluidically connecting the fuel metering unit to the fuel nozzles, the method comprising the steps of:
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providing a temporary sump connected to the fuel manifold; suctioning sufficient fuel into the sump upon engine shut-down to prevent coking of the nozzles; temporarily storing the fuel in the sump while the engine is inoperative; and returning the stored fuel from the sump to the fuel system during the next engine start-up.
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19. A fuel system for use in an aircraft engine, the fuel system comprising:
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a fuel pump for pressurizing fuel from a fuel supply, a plurality of fuel nozzles arranged in a combustion chamber, a fuel metering unit for controlling the flow of fuel from the fuel pump to the fuel nozzles; a fuel manifold fluidically connecting the fuel metering unit to the fuel nozzles; an ecology valve fluidically connected to the fuel manifold, the ecology valve having a reservoir for temporary storage of fuel in the manifold, reservoir control means for suctioning sufficient fuel from the manifold into the reservoir upon engine shut-down to prevent coking of the nozzles and for temporary storage and return of the temporarily stored fuel to the manifold for combustion in the next engine operating cycle; the reservoir having sufficient capacity to receive and temporarily store a volume of fuel at least equal to the volume of fuel remaining in the fuel manifold upon engine shut-down; and the reservoir control means varying the volume of the reservoir to suction fuel from the manifold upon engine shut-down and for return of the fuel to the manifold upon engine start-up.
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20. An ecology valve for use in an aircraft engine fuel system, the fuel system having a fuel pump for pressurizing the fuel in a fuel supply, a fuel metering unit for modulating the fuel flow rate from the fuel supply via a manifold to a set of fuel nozzles, the ecology valve comprising:
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a reservoir connected to the fuel manifold for temporary storage of fuel; and reservoir control means for suctioning sufficient fuel into the reservoir to prevent coking of the nozzles upon engine shut-down for temporary storage and return of the temporarily stored fuel for combustion in the next engine operating cycle.
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Specification