Lubrication Fluid Heating for Cold-Weather Hybrid Propulsion Batteries
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Solution Overview
Problem
Batteries in hybrid electric propulsion systems for aircraft perform poorly in cold weather due to reduced chemical reaction rates, necessitating larger or additional batteries, which increases weight and reduces system attractiveness.
Innovation Solution
A lubrication system that includes a pump to circulate engine lubrication fluid to both the battery and electric motor, providing thermal energy to maintain them above a temperature threshold, using either an electric heating element or the motor's frictional heat to warm the gearbox lubrication fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of batteries is increased or bigger batteries are used to provide sufficient electrical power in cold weather, then the power performance is improved, but the weight increases
Solution Approach 1:
The system performs preliminary heating action on the batteries before they are needed for full power operation in cold weather. The lubrication system heats the batteries in advance during engine operation, so when electrical power is needed, the batteries are already at optimal temperature and can deliver full power without requiring additional battery capacity or weight.
Solution Approach 2:
The patent introduces a lubrication system as an intermediary thermal management system. This lubrication system, already present for engine lubrication, is used as a heat transfer medium to warm the batteries. This intermediary approach allows efficient heat transfer from the engine to the batteries without requiring direct thermal contact or additional heating equipment.
2Power
If the number of batteries is increased or bigger batteries are used to provide sufficient electrical power in cold weather, then the power performance is improved, but the system complexity increases
Solution Approach 1:
The lubrication system serves multiple functions: it provides lubrication for the engine and simultaneously serves as a thermal management system for heating the batteries. This multi-functionality eliminates the need for separate heating equipment, reducing system complexity while ensuring batteries can deliver sufficient power in cold weather.
Solution Approach 2:
The system uses the engine's own operational heat as a resource to warm the batteries. The lubrication system circulates warm oil from the engine to the batteries, allowing the system to self-regulate temperature without requiring external power sources or complex control systems. The batteries are heated by waste heat that would otherwise be lost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Maintains battery and electric motor efficiency and capacity by keeping them above zero degrees Celsius, reducing the need for additional batteries and weight penalties.
Implementation Method 1
A lubrication system that includes a pump to circulate engine lubrication fluid to both the battery and electric motor, providing thermal energy to maintain them above a temperature threshold
Implementation Method 2
using either an electric heating element or the motor's frictional heat to warm the gearbox lubrication fluid
Implementation Method 3
using either an electric heating element or the motor's frictional heat to warm the gearbox lubrication fluid
Data Source
AI summary
A hybrid electric propulsion system includes a gearbox, an electric motor operably coupled to the gearbox, a battery operably coupled to the electric motor to power the electric motor, and an engine lubrication system. The engine lubrication system includes a tank that holds an engine lubrication fluid. The engine lubrication system includes a pump that is configured to pump the lubrication fluid from the tank toward one or both of the battery and the electric motor through a supply line to maintain one or both of the battery and the electric motor above a threshold temperature.