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US 9,206,775 B2Granted
Fuel preheating using electric pump
AssigneeUnited Technologies Corporation
InventorsDavid Lloyd Ripley, Behzad Hagshenas
Life of this patent
Estimating the term…
Abstract
A fuel system for an auxiliary power unit includes a mechanical fuel pump, an electric fuel pump, and a controller. The mechanical fuel pump provides fuel flow to the auxiliary power unit and has an output dependent upon an operational speed of the auxiliary power unit. The electric fuel pump is located in flow series with the mechanical fuel pump. The controller causes the electric fuel pump to circulate and thereby warm fuel prior to start up of the auxiliary power unit.
Claims17
A fuel system for an auxiliary power unit, the fuel system comprising:
- a mechanical fuel pump for providing fuel flow to the auxiliary power unit, the mechanical fuel pump having an output dependent upon an operational speed of the auxiliary power unit;
- an electric fuel pump located in series with the mechanical fuel pump, wherein the electric fuel pump is located upstream of the mechanical fuel pump on a common fuel supply conduit, wherein the electric fuel pump is driven independently of the operational speed of the auxiliary power unit;
- a relief fuel conduit having a first end and a second end, the first end fluidly connected to the fuel supply conduit downstream of the electric fuel pump and the second end fluidly connected to the fuel supply conduit upstream of the electric fuel pump;
- a relief check valve located on the relief fuel conduit, the check valve having an open configuration for allowing fuel to flow from the first end to the second end of the relief fuel conduit;
- and
- a controller configured to cause the electric fuel pump to circulate fuel from the first end to the second end of the relief fuel circuit prior to start-up of the auxiliary power unit.
3 more elements
A fuel system for an auxiliary power unit, the fuel system comprising:
- a fuel supply conduit fluidly connecting a fuel reservoir to a combustor;
- a fuel metering unit located on the fuel supply conduit upstream of the combustor;
- a mechanical gear driven pump located on the fuel supply conduit upstream of the fuel metering unit;
- a mechanical boost pump located on the fuel supply conduit upstream of the mechanical gear driven pump;
- an electric fuel pump located on the fuel supply conduit upstream of the mechanical gear driven pump, wherein the electric fuel pump is driven independently of an operational speed of the auxiliary power unit;
- a fuel shut-off valve located on the fuel supply conduit between the fuel metering unit and the combustor, the fuel shut-off valve having an open configuration and a closed configuration;
- a relief fuel conduit fluidly connecting an outlet of the electric fuel pump to an inlet of the electric fuel pump, wherein fuel flows along the relief fuel conduit when the fuel shut-off valve is in the closed configuration;
- and
- a controller configured to command the electric fuel pump to circulate fuel through the relief fuel conduit prior to start-up of the auxiliary power unit.
6 more elements
A method for providing warmed fuel to an auxiliary power unit, the method comprising:
- providing a fuel reservoir fluidly connected to a combustor of the auxiliary power unit by a fuel supply conduit;
- providing a mechanical boost pump, a mechanical gear-driven pump, a fuel metering unit, and a shut-off valve disposed along the fuel supply conduit in flow series;
- commanding the shut-off valve to close and prevent fuel from flowing to the auxiliary power unit, wherein the shut-off valve has an open configuration and a closed configuration;
- using a controller to provide power to an electric pump and to cause the electric pump to circulate and thereby warm fuel prior to start-up of the auxiliary power unit, wherein the electric pump is located along the fuel supply conduit upstream from the mechanical gear pump and is driven independently of an operational speed of the auxiliary power unit, and wherein fuel circulates along a relief conduit fluidly connecting an outlet to an inlet of the electric pump;
- and
- commanding the shut-off valve to open and allow fuel to flow into the auxiliary power unit.
3 more elements
Dependencies are inferred from the claim text.