Dual pump fuel delivery for an aircraft

A dual pump fuel delivery system for an aircraft includes a fixed displacement fuel pump including an inlet and an outlet. The fixed displacement fuel pump is configured to supply a first portion of a fuel demand for the aircraft. A variable displacement fuel pump including an inlet portion and an outlet portion includes a selectively adjustable pump actuator configured to supply a second portion of the fuel demand. The second portion is variable. A fuel demand sensor operates to detect a selected fuel demand. A control member is operatively connected to the fuel demand sensor and the variable displacement fuel pump. The control member being configured to operate to adjust the variable displacement fuel pump to output the second portion of the fuel demand to satisfy the selected fuel demand.

BACKGROUND

Exemplary embodiments pertain to the art of aircraft and, more particularly, to a dual pump fuel delivery system for aircraft.

Aircraft typically employ a fixed displacement pump to deliver fuel to combustors. The fixed displacement pump is sized to deliver a fuel flow that satisfies a peak flow demand operating condition such as takeoff. In other than peak flow demand operating conditions, a portion of fuel needed to satisfy demand is passed to the combustor while the remaining portion of the fuel is bypassing the combustors to serve other purposes.

BRIEF DESCRIPTION

Disclosed in accordance with a non-limiting example, is a dual pump fuel delivery system for an aircraft including a fixed displacement fuel pump including an inlet and an outlet. The fixed displacement fuel pump is configured to supply a first portion of a fuel demand for the aircraft. A variable displacement fuel pump including an inlet portion and an outlet portion includes a selectively adjustable pump actuator configured to supply a second portion of the fuel demand. The second portion is variable. A fuel demand sensor operates to detect a selected fuel demand. A control member is operatively connected to the fuel demand sensor and the variable displacement fuel pump. The control member being configured to operate to adjust the variable displacement fuel pump to output the second portion of the fuel demand to satisfy the selected fuel demand.

Additionally, or alternatively, in this or other non-limiting examples, the first seal member includes a pressure regulating valve (PRV) fluidically connected between the fixed displacement fuel pump and the variable displacement fuel pump, the PRV including a bypass outlet configured to deliver a bypass fuel flow from the first portion of the fuel flow and the second portion of the fuel flow to one of the inlet and the inlet portion.

Additionally, or alternatively, in this or other non-limiting examples, the first seal member includes the control member comprises a first control member operatively connected to the PRV and a second control member operatively connected to the pump actuator.

Additionally, or alternatively, in this or other non-limiting examples, the first seal member includes the control member is operatively connected to the PRV.

Additionally, or alternatively, in this or other non-limiting examples, the first seal member includes the bypass outlet of the PRV is operatively connected to the pump actuator.

Additionally, or alternatively, in this or other non-limiting examples, the first seal member includes the control member includes a control input coupled to the outlet and the outlet portion, a first control output connected to the control member and a second control outlet connected to the pump actuator.

Additionally, or alternatively, in this or other non-limiting examples, the first seal member includes the control member comprises an electro-hydraulic servo valve (EHSV).

Also disclosed in accordance with a non-limiting example is an aircraft engine system including a compressor portion including a number of compressor stages, a turbine portion, a combustor fluidically connected to the compressor portion and the turbine portion, and a dual pump fuel delivery system connected to the combustor assembly. The dual pump fuel delivery system includes a fixed displacement fuel pump including an inlet and an outlet. The fixed displacement fuel pump is configured to supply a first portion of a fuel demand for the aircraft. A variable displacement fuel pump including an inlet portion and an outlet portion includes a selectively adjustable pump actuator configured to supply a second portion of the fuel demand. The second portion is variable. A fuel demand sensor operates to detect a selected fuel demand. A control member is operatively connected to the fuel demand sensor and the variable displacement fuel pump. The control member being configured to operate to adjust the variable displacement fuel pump to output the second portion of the fuel demand to satisfy the selected fuel demand.

Additionally, or alternatively, in this or other non-limiting examples, a pressure regulating valve (PRV) fluidically connected between the fixed displacement fuel pump and the variable displacement fuel pump, the PRV including a bypass outlet configured to deliver a bypass fuel flow from the first portion of the fuel flow and the second portion of the fuel flow to one of the inlet and the inlet portion.

Additionally, or alternatively, in this or other non-limiting examples, the control member comprises a first control member operatively connected to the PRV and a second control member operatively connected to the pump actuator.

Additionally, or alternatively, in this or other non-limiting examples, the control member is operatively connected to the PRV.

Additionally, or alternatively, in this or other non-limiting examples, the bypass outlet of the PRV is operatively connected to the pump actuator.

Additionally, or alternatively, in this or other non-limiting examples, the control member includes a control input coupled to the outlet and the outlet portion, a first control output connected to the control member and a second control outlet connected to the pump actuator.

Further disclosed in accordance with a non-limiting example is a method of satisfying fuel demand in an engine of an aircraft including generating a first portion of a fuel flow in a first pump of a fuel system, generating a second portion of the fuel flow in a second pump of the fuel system, determining a fuel flow demand for the engine, sensing a combined fuel pressure of the first portion of the fuel flow and the second portion of the fuel flow, and adjusting the second portion of the fuel flow to meet the fuel flow demand.

Additionally, or alternatively, in this or other non-limiting examples adjusting the second portion of the fuel flow includes controlling a pump actuator of the second pump.

Additionally, or alternatively, in this or other non-limiting examples, controlling the pump actuator includes adjusting an output of an electro-hydraulic servo valve (EHSV) connected to the pump actuator.

Additionally, or alternatively, in this or other non-limiting examples, controlling the pump actuator includes adjusting a bypass outlet of a pressure regulating valve (PRV).

Additionally, or alternatively, in this or other non-limiting examples, adjusting the bypass outlet includes adjusting a position of the PRV with an EHSV.

Additionally, or alternatively, in this or other non-limiting examples, the method also includes creating a bypass flow from the first portion of the fuel flow and the second portion of the fuel flow by adjusting a pressure regulating valve with a first output of a flow controller and adjusting the second portion of the fuel flow by controlling the pump actuator of the second pump with a second output of the flow controller.

Additionally, or alternatively, in this or other non-limiting examples, generating the first portion of the fuel flow includes creating a steady state flow demand with the first pump.

DETAILED DESCRIPTION

An air-breathing aircraft engine system is indicated generally at5inFIG.1. Air-breathing aircraft engine system5includes a compressor portion8operatively coupled to a turbine portion10through a shaft12. A combustor assembly14is fluidically connected between compressor portion8and turbine portion10. A dual pump fuel delivery system20fluidically connects combustor assembly14with a source of fuel24. Dual pump fuel delivery system20may receive fuel directly from source of fuel24or, through a compressor stage (not shown) that creates an input pressure for the fuel.

Reference will now follow toFIG.2in describing dual pump fuel delivery system20in accordance with a non-limiting example. Dual pump fuel delivery system20includes an inlet30fluidically coupled to source of fuel24and an outlet34fluidically coupled to combustor assembly14. Inlet30is connected to a first or fixed displacement pump40and a second or variable displacement pump42having a pump actuator44. In a non-limiting example, fixed displacement pump40is sized to provide fuel to combustor assembly14during a steady-state or cruise mode of operation. During transitionary phases of flight such as take-off, landing, or altitude changes, variable displacement pump42is employed to meet an increased fuel demand.

In a non-limiting example, dual pump fuel delivery system20includes a pressure regulating valve (PRV)48coupled to fixed displacement pump40through a first outlet line52and to variable displacement pump42through a second outlet line54. Fuel flow from fixed displacement pump40in first outlet line52and fuel flow from variable displacement pump42combine in combined fuel flow line56. The combined fuel flows into PRV48through an actuator line58and a bypass inlet60. Flow flows from bypass inlet60through PRV48, to a bypass outlet62where it is returned to inlet30. Fuel entering actuator line58acts on a spool64in PRV48against a spring66to adjust an amount of bypass flow passing through PRV48as will be detailed more fully herein.

In a non-limiting example, dual pump fuel delivery system20includes a first control member69connected between combined fuel flow line56and PRV48and a second control member71connected between combined fuel flow line56and pump actuator44. In a non-limiting example, first control member69may take the form of a first electro-hydraulic servo valve (EHSV)74and second control member71may take the form of a second electro-hydraulic servo valve (EHSV)76.

In a non-limiting example, first EHSV74includes a first control input78connected to combined fuel flow line56and a first control output80connected to PRV48. Second EHSV76includes a second control input83connected to combined fuel flow line56and a second control output85connected to pump actuator44. As will be detailed more fully herein, first EHSV74delivers a control pressure to PRV48that cooperates with actuation pressure in actuator line58to establish a selected amount of bypass flow through spool64. Second EHSV76delivers actuation pressure to pump actuator44to establish a selected fuel output from variable displacement pump42.

In a non-limiting example, a fuel demand sensor88is connected to combined fuel flow line56. Fuel demand sensor88detects an amount of fuel pressure in combined fuel flow line56. A controller92is operatively connected to fuel demand sensor88. Controller92determines an amount of fuel demand for air-breathing aircraft engine5system, and signals first EHSV74through a first control output94and second EHSV76through a second control output96to control PRV48and pump actuator44respectively to deliver a selected fuel pressure to meet the fuel demand.

In a non-limiting example, during steady-state flight operations, fixed displacement pump40delivers fuel to combustor assembly14. Controller92signals second EHSV76to control variable displacement pump42to produce minimal fuel flow. First EHSV74shifts spool64so as to establish a selected amount of bypass flow. The selected amount of bypass flow may be equal to the minimum fuel flow from variable displacement pump42. During other stages of flight, such as take-off, landing, or altitude changes, controller92may signal second EHSV76to produce additional fuel to meet an increasing demand.

Controller92tracks fuel pressure through fuel demand sensor88and signals second EHSV76to adjust pump actuator44to meet the demand. First EHSV74controls PRV48to reduce over supply by adjusting bypass flow. In this manner, dual pump fuel delivery system20establishes a thrust specific fuel consumption amount that more closely matches actual fuel demand.

FIG.3, in which like reference numbers represent corresponding parts in the respective views, depicts dual pump fuel delivery system20in accordance with another non-limiting example. Instead of multiple control members, a single EHSV98controls both PRV48and pump actuator44. In a non-limiting example, EHSV98receives signals from controller92to adjust a position of spool64to meet fuel demand. In steady-state conditions, controller92reduces bypass flow through PRV48. Bypass flow pressure passes through a pump actuator control line100to pump actuator44.

Reduced bypass flow pressure through pump actuator control line100as established by controller92causes pump actuator44to reduce output from variable displacement pump42. As fuel demand increases and controller92increases bypass flow, pressure through pump actuator control line100increases to signal variable displacement pump42to produce additional flow. In a non-limiting example, control flow passing through EHSV98may be returned to inlet30through a control bypass flow line106.

FIG.4, in which like reference numbers represent corresponding parts in the respective views, depicts dual pump fuel delivery system20in accordance with another non-limiting example. In the non-limiting example shown, a single EHSV120is connected to PRV48and pump actuator44. EHSV120includes first control input78, a first control output130connected to PRV48and a second control output140connected to pump actuator44. As fuel demand changes, controller92signals EHSV120to produce additional fuel pressure by reducing bypass flow and increasing output from variable displacement pump42or less fuel pressure by increasing bypass flow and reducing output from variable displacement pump42. In each of the non-limiting examples described herein, dual pump fuel delivery system20establishes a thrust specific fuel consumption amount that more closely matches actual fuel demand.