Free Turbine Turbogenerator With Single-Coupling Reversible Machine
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Solution Overview
Problem
Existing turboshaft engines for helicopters face issues with weight, cost, and complexity due to the need for multiple electrical machines for start-up and power generation, which affect engine performance and efficiency, especially in applications with low inertia mechanisms like electrically-driven rotary wing aircraft.
Innovation Solution
A turbomachine with a simplified coupling system using a single mechanical coupling means, such as a free wheel, directly connects the electrical machine to the free turbine shaft, allowing it to drive both the gas generator and free turbine during start-up, and switches to generator mode when the gas generator becomes autonomous, optimizing weight, cost, and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple electrical machines are used for start-up and power generation, then the engine can perform both functions, but the weight, cost, and complexity increase
Solution Approach 1:
The electrical machine is designed to perform multiple functions: acting as a motor during start-up to rotate the gas generator, and as a generator during operation to produce electrical power. This multi-functionality eliminates the need for separate dedicated machines, reducing weight while maintaining adaptability
Solution Approach 2:
The patent combines the start-up motor function and power generation function into a single electrical machine integrated with the free turbine shaft, rather than using separate machines. This merging reduces the number of components, simplifies the system, and decreases overall weight
2Adaptability or versatility
If multiple electrical machines are used for start-up and power generation, then the engine can perform both functions, but the device complexity increases
Solution Approach 1:
The electrical machine serves dual purposes as both motor and generator, reducing the number of discrete components and simplifying the overall system architecture while maintaining full functional capability
Solution Approach 2:
By integrating the start-up and power generation functions into one electrical machine connected to the free turbine shaft, the patent reduces system complexity and the number of mechanical couplings required
3Ease of operation
If the electrical machine is mechanically coupled to the gas generator shaft, then it can drive the gas generator during start-up, but it cannot drive the free turbine during start-up
Solution Approach 1:
The free turbine shaft acts as an intermediary mechanical connection, allowing the electrical machine to transmit rotational force to both the gas generator (via the turbine-compressor connection) and the free turbine simultaneously, enabling dual driving capability
Solution Approach 2:
The mechanical coupling is segmented into two paths: one through the gas generator turbine-compressor connection, and another direct connection to the free turbine, allowing independent control and driving of both components
4Weight of moving object
If a simplified coupling system with a single mechanical coupling means is used, then weight and cost are reduced, but the switching between motor and generator modes must be more reliable
Solution Approach 1:
The free wheel provides automatic, dynamic switching based on rotational speed differential: when the gas generator shaft rotates faster than the free turbine shaft, the free wheel engages to couple them; when the reverse occurs, it automatically disengages. This passive dynamic mechanism ensures reliable mode transitions without adding weight
Solution Approach 2:
The free wheel mechanism automatically performs the switching function based on the relative speeds of the two shafts, requiring no external control system or additional components. The system self-regulates the mechanical coupling state based on operating conditions
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 solution reduces weight and cost while enhancing reliability and efficiency by simplifying the switching system, enabling high-power electrical generation and torque delivery without penalizing the gas generator's performance.
Implementation Method 1
The free turbine shaft is directly mechanically connected to said electrical machine during all the operating phases of the turbomachine, and the turbomachine further comprises a single mechanical coupling means configured to mechanically couple the gas generator shaft to the free turbine shaft when both shafts are rotating at substantially the same rotation speed, and to mechanically uncouple the gas generator shaft from the free turbine shaft when the rotation speed of both shafts differs
Implementation Method 2
the electrical machine is sized to drive both the gas generator and the free turbine during start-up of the turbomachine... the electrical machine (11) generates electrical power by taking mechanical power from the shaft (17) of the free turbine (12)
Implementation Method 3
the electrical machine (11) is sized to drive both the gas generator (13) and the free turbine (12) during start-up of the turbomachine (10)
Implementation Method 4
fresh air entering into the turboshaft engine is compressed due to the rotation of the compressor before being sent to a combustion chamber where it is mixed with a fuel. The gases burned during the combustion
Implementation Method 5
The operating principle is as follows: fresh air entering into the turboshaft engine is compressed due to the rotation of the compressor before being sent to a combustion chamber where it is mixed with a fuel. The gases burned during the combustion are then evacuated at high speed. There is then a first expansion in the turbine of the gas generator
Data Source
AI summary
Disclosed is a turbogenerator, in particular for an electrically-driven rotary wing aircraft, comprising a gas generator equipped with a first shaft, at least one reversible electrical machine, and a free turbine provided with a second shaft and caused to rotate by a gas flow generated by the gas generator. The second shaft is coupled to the at least one electrical machine during all phases of operation of the turbomachine, and the turbomachine further comprises a single mechanical coupling means for coupling the first mechanical shaft to the second mechanical shaft when the electrical machine is operating in motor mode and mechanically uncoupling the first mechanical shaft from the second mechanical shaft when the electrical machine is operating in generator mode.