Dual Electric Machines in Turboprop Reduction Gears for Load Balancing
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Solution Overview
Problem
Existing turboprop engines face challenges in integrating powerful electric machines within the mechanical speed reduction gear without increasing overall dimensions, particularly in balancing loads between intermediate lines in compound reduction gear configurations.
Innovation Solution
The integration of two electric machines, each with a rotor driven by an intermediate line, distributes total electrical power across two separate lines, regulating load imbalances and maintaining compact dimensions by using parallel transmission lines within the compound reduction gear architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single powerful electric machine is integrated within the speed reduction gear, then electrical power output is improved, but the volume and overall dimensions of the reduction gear increase
Solution Approach 1:
The patent divides a single powerful electric machine into two separate electric machines with lower individual power ratings. These two machines are integrated into the speed reduction gear, collectively providing the required total electrical power output while each machine occupying less individual space, thereby resolving the contradiction between power output and volume constraints
Solution Approach 2:
The two electric machines are nested within the existing speed reduction gear structure, utilizing the available internal volume efficiently. The electric machines are positioned within the gear housing, with their rotors coupled to intermediate shafts and stators mounted on the gear casing, allowing integration without significantly increasing the overall external dimensions of the reduction gear assembly
2Reliability
If two electric machines are integrated into the speed reduction gear, then load balancing between intermediate lines is improved, but device complexity increases
Solution Approach 1:
The two electric machines serve multiple functions: they can operate independently to balance loads on different intermediate lines, can work together to provide combined electrical power output, and can function as generators during regenerative braking. This multi-functionality improves reliability and load balancing while the modular design keeps the added complexity manageable
Solution Approach 2:
The patent introduces intermediate shafts and coupling mechanisms that mediate between the two electric machines and the main power transmission path. These intermediary elements facilitate load distribution and power transfer while maintaining a structured and manageable system architecture, preventing excessive complexity
3Volume of moving object
If the stator extends radially outside the rotor, then integration within the reduction gear volume is improved, but radial dimensions of the assembly increase
Solution Approach 1:
The patent utilizes the axial dimension of the speed reduction gear by positioning the stator to extend axially beyond the rotor in certain configurations, rather than only radially. This dimensional transition allows the electric machines to fit within the available volume of the reduction gear housing while minimizing the increase in radial dimensions, accommodating the stator within the gear's axial length
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
This configuration allows for balanced power distribution between transmission lines, reducing axial dimensions and maintaining radial and axial overall dimensions, enabling efficient power injection and balancing loads without impacting the engine's size.
Implementation Method 1
each electric machine comprising a rotor and a stator... each rotor being driven in rotation respectively by a pinion of an intermediate line
Data Source
AI summary
The disclosure relates to an assembly for an aircraft turbomachine, having a speed reduction gear comprising an input pinion connected to a power shaft of the turbomachine and an output pinion connected to a propeller shaft of the turbomachine. According to the disclosure, the assembly includes two electric machines which are each configured to provide electrical power to the propeller shaft or to draw mechanical power from the propeller shaft, each electric machine comprising a rotor and a stator, the stator configured to be connected to a casing of the turbomachine. The speed reduction gear can include two substantially parallel intermediate transmission lines configured to transmit the torque from the input pinion to the output pinion, each rotor being driven in rotation respectively by a pinion of an intermediate line.