Starter Generator Nested Housing for Gas Turbine Accessory Gearbox
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Solution Overview
Problem
Gas turbine engines face challenges in efficiently integrating starter/generators with accessory gearboxes due to spatial limitations and high overhung moments, which affect power output and weight, particularly in aircraft applications where size and weight are critical.
Innovation Solution
The integration of a starter/generator assembly with a nested housing configuration that positions the permanent magnet generator and exciter closer to the pinion gear, reducing the overhung moment and allowing for higher rotational speeds and power output, while minimizing the assembly's size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the starter/generator is integrated with the accessory gearbox using a conventional mounting configuration, then the assembly is structurally simple and easy to manufacture, but the overhung moment is high which limits power output and increases weight
Solution Approach 1:
The patent applies nesting by placing the starter/generator assembly inside the accessory gearbox housing. The SG housing is positioned within the AGB housing such that the SG pinion gear meshes with the AGB drive gear, while the SG rotor and electromagnetic components are contained within the SG housing. This nested configuration reduces the overhung moment by positioning the SG closer to the drive gear, thereby increasing power output while managing structural complexity.
2Speed
If the permanent magnet generator and exciter are positioned farther from the pinion gear, then the assembly is easier to manufacture with standard component placement, but the overhung moment increases reducing rotational speed and power output
Solution Approach 1:
The patent applies local quality by positioning the permanent magnet generator and exciter in specific locations within the SG housing to optimize the overhung moment. The PMG and exciter are placed on the SG rotor such that their combined center of gravity, along with the armature, is positioned at a predetermined location that minimizes the overhung moment. This allows the rotor to achieve higher rotational speeds and power output while maintaining manufacturability through standardized housing and component integration.
3Power
If the starter/generator assembly is designed to minimize size and weight, then the assembly meets aircraft weight constraints, but the power output capacity is reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the physical dimensions and material properties of the starter/generator components. The SG housing and rotor are designed with specific size parameters that balance power output capacity with weight constraints. The electromagnetic components, including the permanent magnets and windings, are sized and positioned to provide the required power output while minimizing the overall assembly weight. This allows the SG to meet aircraft weight constraints while maintaining adequate power output capacity for both starting and generation functions.
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 enhances power output, reduces weight, and minimizes overhung moments, addressing spatial constraints and power requirements in gas turbine engines by optimizing the placement of components within the accessory gearbox.
Implementation Method 1
a permanent magnet generator (PMG), an exciter, and a main machine
Implementation Method 2
an exciter, and a main machine
Data Source
AI summary
An assembly for a gas turbine engine comprising an accessory gearbox comprising a drive gear and a starter/generator mechanically mounted to the accessory gearbox. The starter/generator comprising a rotatable shaft, a pinion gear carried by the shaft, a main machine carried by the shaft, a permanent magnet generator (PMG) carried by the shaft and an exciter carried by the shaft.