Electromagnetic Coupling for Gas Turbine Torque Transfer
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Solution Overview
Problem
Current systems for transferring torque between coaxial spools in gas turbine engines face challenges such as weight, reliability, and operational flexibility issues, particularly when dealing with the wide rotational speed range of lower pressure spools, which are not compatible with electrical power generation requirements, especially at idle conditions.
Innovation Solution
An electro-magnetic coupling system with a first rotor carrying magnetic flux-producing formations, a second rotor with interpoles to modulate magnetic fields, and a stator with electrical winding coils that can generate a second magnetic field to transfer torque between spools, allowing for compact design and high power density, with the ability to engage or disengage torque transfer as needed and operate as an electrical generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If mechanical gearing is used to transfer torque between spools, then torque transfer capability is improved, but weight and device complexity increase
Solution Approach 1:
The patent replaces the mechanical gearing system with an electro-magnetic coupling system consisting of a first rotor, second rotor, and stator with electrical winding coils. This substitution eliminates the need for physical gears and shafts, thereby reducing weight and device complexity while maintaining torque transfer capability through magnetic field interaction between the rotors and stator.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary to transfer torque between the first rotor and second rotor. The first rotor produces a magnetic field that interacts with the second rotor through the stator, enabling torque transfer without direct mechanical contact. This intermediary approach reduces mechanical complexity and weight compared to traditional gear systems.
2Power
If power is extracted from lower pressure spool, then power availability is improved, but generator mass increases due to wide speed range
Solution Approach 1:
The patent uses the electro-magnetic coupling system to control and adjust the operational parameters of the lower pressure spool, enabling it to operate at speeds compatible with electrical generator requirements. By modulating the magnetic fields and controlling the interaction between rotors, the system can extract power while maintaining speed within acceptable ranges, thereby avoiding the need for an oversized generator.
Solution Approach 2:
The electro-magnetic coupling system serves multiple functions: it transfers torque between spools, enables power extraction from the lower pressure spool, and simultaneously controls speed compatibility for generator operation. This multi-functionality eliminates the need for separate speed control mechanisms and oversized generator design, reducing overall system mass.
3Power
If fixed gear ratio is used between lower pressure spool and generator, then power extraction is enabled, but device complexity and mass increase
Solution Approach 1:
The patent replaces the fixed gear ratio mechanical system with a controllable electro-magnetic coupling system. The interaction between the first rotor, second rotor, and stator allows for flexible power extraction without the need for fixed mechanical gearing. This substitution reduces device complexity by eliminating gears, shafts, and associated mounting structures while enabling power extraction through magnetic field control.
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 provides efficient torque transfer and electrical power generation with high power density, addressing the compatibility issues with wide speed ranges and enabling operation at multiple engine conditions without significant mass increase, thus enhancing engine operability and flexibility.
Implementation Method 1
the first rotor carries a plurality of magnetic flux-producing formations which produce a first magnetic field
Implementation Method 2
the stator carries a plurality of electrical winding coils which are energisable to generate a second magnetic field
Implementation Method 3
the second rotor carries an arrangement of interpoles which modulate the first and second magnetic fields such that the modulated fields interact to transfer torque between the spools
Data Source
Figure 1~2
Figure 3~4
AI summary
An electro-magnetic coupling system for transferring torque between a pair of coaxial spools of a gas turbine engine is provided. The system includes a first rotor rotatable with one of the spools, a second rotor rotatable with the other of the spools, and a stator. The first and second rotors and the stator are coaxial with each other. The second rotor operably couples the first rotor and the stator. The first rotor carries a plurality of magnetic flux-producing formations which produce a first magnetic field. The stator carries a plurality of electrical winding coils which are energisable to generate a second magnetic field. The second rotor carries an arrangement of interpoles which modulate the first and second magnetic fields such that the modulated fields interact to transfer torque between the spools.