Hybrid Aircraft Propulsion Assembly With Reversible Electric Coupling
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Solution Overview
Problem
Existing propulsion systems for twin-engine or multi-engine aircraft require a large number of electrical machines, some with excessive power outputs, leading to an unsatisfactory architecture that is not optimized for efficiency and simplicity.
Innovation Solution
A propulsion system for hybrid aircraft featuring at least one first and second gas turbine, each with a gas generator and a free turbine, coupled to a main rotor via coupling means, and two reversible electric machines that can alternate between directions of rotation to perform various functions, including starting and restarting gas generators, supplying power to the main rotor, and ensuring redundancy, while minimizing the number of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing propulsion systems use multiple electrical machines with high power outputs to perform starting, standby, and power supply functions, then reliability and functionality are improved, but device complexity and overall mass increase
Solution Approach 1:
The patent applies multi-functionality by enabling a single reversible electric machine to perform multiple functions: acting as a starter for the gas generator, serving as a standby power source, and functioning as a generator during flight. The machine can rotate in two directions to differentially engage with either the gas generator or main rotor, allowing one component to replace what traditionally required four separate electrical machines, thereby reducing complexity while maintaining reliability
Solution Approach 2:
The patent merges multiple functions into a single reversible electric machine. By combining the starter, standby, and generator functions into one unified component that can operate in motor and generator modes with bidirectional rotation, the system consolidates what would traditionally require multiple separate machines, directly addressing the contradiction between reliability and device complexity
2Adaptability or versatility
If existing propulsion systems use multiple electrical machines with high power outputs to perform starting, standby, and power supply functions, then functionality is improved, but overall mass increases
Solution Approach 1:
The reversible electric machine serves multiple operational functions including starting the gas generator, providing standby power, and generating electricity during flight. By designing one machine to perform what traditionally required four separate machines, the patent significantly reduces the overall mass of the propulsion system while preserving full operational versatility
Solution Approach 2:
The patent merges starter, standby, and generator functions into a single reversible electric machine, eliminating the mass of multiple high-power machines. The bidirectional rotation capability allows one component to replace multiple components, directly reducing overall mass while maintaining adaptability
3Reliability
If one gas turbine is kept in standby mode for rapid restart capability, then flight safety is improved, but fuel consumption increases
Solution Approach 1:
The patent implements preliminary action by maintaining one gas turbine in standby mode with its gas generator already primed and capable of immediate ignition. The reversible electric machine can quickly restart the standby turbine if needed, ensuring rapid response to power failures. This pre-positioned readiness improves safety while the electric machine's efficiency helps mitigate the fuel consumption penalty of maintaining standby capability
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
The system simplifies the architecture by reducing the number of electrical machines, ensuring redundancy, and optimizing fuel consumption by maintaining one gas turbine in standby mode, allowing rapid restarts and internal hybridization, thus enhancing flight safety and reducing overall mass.
Implementation Method 1
each capable of being coupled to the gas generator of the first gas turbine and the second gas turbine respectively, via a first switchable coupling means, and of being each coupled to the main rotor via a second switchable coupling means
Implementation Method 2
fresh air entering the gas turbine is compressed by the compressor's rotation before being sent to a combustion chamber where it is mixed with fuel. The exhaust gases from combustion are then expelled at high speed
Implementation Method 3
A first expansion occurs in the gas generator's turbine, during which it extracts the energy necessary to drive the compressor. The gas generator's turbine does not absorb all the kinetic energy of the exhaust gases; the excess kinetic energy corresponds to the gas flow generated by the gas generator
Data Source
Figure 1
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AI summary
A propulsive assembly (100) for a multi-engine hybrid aircraft, comprising a first and a second gas turbine (10, 20) each having a gas generator (12, 22) and a free turbine (11, 21), a main rotor (62) coupled to the free turbine (11, 21) via a first and a second main coupling means (51, 52), a first and a second reversible electric machine (30, 40) each coupled to the gas generator (12, 22) via a first deactivatable coupling means (31, 41), and each coupled to the main rotor (62) via a second deactivatable coupling means (32, 42), the first deactivatable coupling means (31, 41) being activated when the electric machines (30, 40) rotate in a first direction of rotation, and the second deactivatable coupling means (32, 42) being activated when the electric machines (30, 40) rotate in a second direction of rotation opposite to the first direction of rotation.