Hybrid Electric Fan Drive for Independent Speed Control
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Solution Overview
Problem
Existing gas turbine engines face challenges in efficiently adjusting fan speed without affecting the speed of the drive turbine and low pressure compressor, leading to operational complications and constraints.
Innovation Solution
Incorporating a first and second clutch assembly between the electric motors and the geared architecture, allowing independent control of fan speed through electric motor assemblies, decoupling the fan speed from the low pressure turbine and geared architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fan speed is adjusted by changing the drive turbine speed, then the fan efficiency is improved, but the low pressure compressor operation becomes complicated and constrained
Solution Approach 1:
The patent divides the drive system into two independent pathways: (1) the traditional turbine-driven pathway that drives the low pressure compressor, and (2) a new electric motor-driven pathway that drives the fan through a gearbox. This segmentation allows the fan speed to be controlled independently via the electric motor without affecting the low pressure compressor operation, thereby resolving the contradiction between improving fan efficiency and maintaining simple compressor operation
Solution Approach 2:
The patent introduces an electric motor as an intermediary device between the power source and the fan. This electric motor acts as a mediator that decouples the fan drive from the turbine drive, allowing independent control of fan speed while the turbine continues to drive the low pressure compressor without complications
2Productivity
If the low pressure compressor speed is changed to adjust fan speed, then the fan performance is improved, but the device complexity increases
Solution Approach 1:
The electric motor assembly serves multiple functions: it acts as a starter motor during engine startup, operates as a drive motor for the fan during normal operation, and can function as a generator during regenerative braking or energy recovery. This multi-functionality justifies the added complexity by providing versatile operational capabilities without requiring separate systems for each function
3Use of energy by moving object
If a geared architecture is used between the fan and drive turbine, then both can operate closer to optimal speeds, but the mechanical linkage still couples their speed changes
Solution Approach 1:
The electric motor assembly serves as an intermediary that decouples the mechanical linkage between the turbine and fan. By introducing this intermediate device, the system maintains the beneficial geared architecture for speed optimization while eliminating the constraint of coupled speed changes, as the electric motor can independently control fan speed regardless of turbine speed
Data Source
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AI summary
A gas turbine engine includes a fan section (22) including a plurality of fan blades (42), a first electric motor assembly (72) that provides a first drive input for driving the fan blades (42) about an axis (A), a turbine section (28), and a geared architecture (48) driven by the turbine section (28) and coupled to the fan section (22) to provide a second drive input for driving the fan blades (42), and a second electric motor assembly (74) is coupled to rotate the geared architecture (48) relative to a fixed structure (36) to control a speed of the fan blades (42) provided by a combination of the first drive input and the second drive input.