Hybrid-Electric Shaft Coupler for Safe Mode Switching
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Solution Overview
Problem
Hybrid-electric propulsion systems face challenges in balancing and shifting power between electric machines and gas turbine engines, as well as safely coupling and decoupling these components for efficient operation and safety.
Innovation Solution
A coupler mechanism is introduced to selectively mechanically couple and decouple the propulsor, power turbine, and electric machine shafts, allowing for smooth transitions between different operational modes by synchronizing speeds and torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gas turbine engine and electric machine are integrated in a hybrid-electric propulsion system, then system efficiency and power flexibility are improved, but operational complexity and safety risks increase due to the need to balance and shift power between components
Solution Approach 1:
A coupler mechanism is introduced as an intermediary device between the gas turbine engine and electric machine shafts. This coupler enables controlled mechanical coupling and decoupling of the two power sources, simplifying power balancing operations by providing a dedicated interface for torque transmission and isolation, thereby reducing operational complexity while maintaining system efficiency
Solution Approach 2:
The system employs dynamic switching capabilities where the coupler can be selectively engaged or disengaged based on operational requirements. This allows the propulsion system to dynamically adjust power distribution between the gas turbine and electric machine, enabling flexible operation across different flight conditions while maintaining simplicity through on-demand coupling/decoupling
2Adaptability or versatility
If the electric machine is mechanically coupled with the gas turbine engine for power sharing, then power flexibility is improved, but safety risks increase due to potential failures in coupling/decoupling these components
Solution Approach 1:
The coupler serves as a safety intermediary that provides controlled mechanical connection and disconnection between the gas turbine and electric machine. This dedicated coupling mechanism includes controlled engagement/disengagement features that reduce the risk of accidental coupling/decoupling events, thereby enhancing safety while maintaining power flexibility
Solution Approach 2:
The system incorporates fail-safe features and controlled coupling/decoupling mechanisms that prepare for potential failures in advance. The coupler design includes features that prevent catastrophic failures by providing controlled separation paths and protection against unintended engagement, cushioning against safety risks before they can manifest
3Reliability
If permanent disconnection is used for component separation, then safety is improved, but system efficiency decreases due to the need for complex repairs and reassembly
Solution Approach 1:
The coupler enables reversible mechanical coupling and decoupling of the gas turbine and electric machine shafts. This dynamic connection allows components to be separated when needed for safety or maintenance, then reconnected without permanent damage or complex repairs, thereby improving ease of repair while maintaining safety through controlled separation
Data Source
AI summary
A propulsion assembly includes a first torque source coupled with a first shaft and a second torque source coupled with a second shaft. A coupler selectively couples the first and second torque sources. When the first and second torque sources are coupled via the coupler, in response to a command to decouple the first torque source, an unloading operation is performed to decrease the torque output provided by the first torque source to a threshold, and when reached, the first shaft is decoupled from the coupler. When the first torque source is coupled with the coupler but the second torque source is not, in response to a command to couple the second torque source, a speed matching operation is performed to increase the speed of the second shaft to match a speed of the first shaft, and when the speeds are matched, the second shaft is coupled to the coupler.