Hybrid Electric Engine Oil Circulation With Independent Pump Control
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Solution Overview
Problem
In hybrid electric engines, reducing low spool speed to transfer power can lead to oil containment issues, limiting the amount of power transfer while maintaining sufficient lubrication.
Innovation Solution
A hybrid electric engine with an oil circulation system that includes a power source, such as a battery or super capacitor, to drive supply and scavenger pumps independently, controlling pressure differentials in bearing compartments using electric motors and controllers, ensuring adequate lubrication without relying solely on fuel combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power is transferred from low spool to high spool to slow down the fan or improve compressor stability, then power transfer capability is improved, but oil containment in bearing compartments deteriorates
Solution Approach 1:
The patent replaces the traditional mechanically coupled oil pump system with an electrically driven oil pump system. The electric oil pump is independently controlled by the controller, allowing it to maintain adequate oil pressure and containment in bearing compartments even when low spool speed is reduced for power transfer. This substitution of mechanical coupling with electrical control resolves the contradiction by decoupling oil supply from spool speed variations.
Solution Approach 2:
The patent changes the control parameter for oil pump operation from mechanical speed coupling to electrical control parameters. The controller independently adjusts the electric oil pump's operation based on bearing compartment oil pressure requirements, rather than being passively driven by spool speed. This parameter change allows maintenance of oil containment during power transfer operations that would previously cause oil starvation.
2Power
If low spool speed is reduced for power transfer, then power transfer capability is improved, but lubrication to bearings deteriorates
Solution Approach 1:
The patent replaces the mechanically coupled oil pump system with an electrically driven oil pump system. The electric oil pump is independently controlled by the controller, allowing it to maintain adequate oil pressure and containment in bearing compartments even when low spool speed is reduced for power transfer. This substitution of mechanical coupling with electrical control resolves the contradiction by decoupling oil supply from spool speed variations.
Solution Approach 2:
The controller monitors bearing compartment conditions and automatically adjusts the electric oil pump operation to maintain adequate lubrication. The system serves itself by detecting lubrication requirements and independently adjusting oil pump output without requiring mechanical coupling to spool speed, ensuring continuous adequate lubrication during power transfer operations.
Data Source
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AI summary
A hybrid electric propulsion system including: a gas turbine engine comprising a low speed spool, a high speed spool, and a combustor; a lubrication circuit comprising a bearing compartment, a supply pump, and a scavenger pump; an electric motor configured to augment rotational power of the low speed spool or the high speed spool; and a controller operable to: control the electric motor based upon a pressure differential between an interior of the bearing compartment and an exterior of the bearing compartment and to drive rotation of the low speed spool and/or the high speed spool via the electric motor responsive to a thrust command while fuel flow to the combustor is inhibited.