Accessory Gearbox Starter Generator Integration
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Solution Overview
Problem
Gas turbine engines require an efficient and compact starter generator assembly that can handle multiple components while minimizing weight and aerodynamic drag, with a need to contain debris and heat generated during mechanical or thermal failures.
Innovation Solution
An Integrated Starter/Generator Gearbox (ISGB) assembly that couples a starter generator with an accessory gearbox, featuring a pinion gear, drive gear, and safety disconnect, where the starter generator is oil-cooled and has a safety disconnect mechanism to prevent debris contamination, and the relative placement of machines reduces the overhung moment and weight, allowing for higher rotational speeds and power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the starter generator is integrated with the accessory gearbox, then weight and size are reduced, but debris containment and protection against contamination become more difficult
Solution Approach 1:
The assembly is segmented into distinct functional zones: the AGB housing contains the pinion gear and drive gear, while the S/G housing contains the starter generator. This segmentation allows debris from gear meshing to be contained within the AGB housing, preventing contamination of the S/G components while maintaining a compact integrated structure.
Solution Approach 2:
The AGB housing acts as an intermediary barrier between the gear train components and the starter generator. It provides physical separation and protection, allowing the integrated assembly to benefit from weight reduction while the housing prevents harmful factors (debris, heat) from affecting the S/G.
2Object-affected harmful factors
If the safety disconnect is located within the S/G housing, then protection against debris is improved, but accessibility for maintenance and repair becomes more difficult
Solution Approach 1:
The S/G housing is nested within or adjacent to the AGB housing, creating a layered protective structure. The safety disconnect is positioned within the S/G housing where it is protected by the housing walls from debris generated by the gear train, while still being accessible through designated service ports or removable housing sections.
3Power
If the relative placement of machines is optimized, then power output and rotational speed are improved, but mechanical stress and stability become more challenging
Solution Approach 1:
The pinion gear and drive gear are positioned in three-dimensional space to optimize the transmission of power while minimizing overhung moments. The S/G is mounted at a specific location and orientation relative to the gear train, allowing high rotational speeds and power output while the housing structure provides mechanical support to manage stresses.
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 assembly achieves reduced weight and size, minimizing aerodynamic drag, and effectively contains debris and heat during failures, enabling higher rotational speeds and power output while maintaining mechanical integrity and preventing oil contamination.
Implementation Method 1
The S/G mounted to the AGB is oil-cooled
Data Source
AI summary
An assembly for a gas turbine engine comprising an accessory gearbox comprising a drive gear and pinion gear and a starter/generator mechanically mounted to the accessory gearbox. The starter/generator comprising a housing and a portion of a rotatable shaft with a safety disconnect where the safety disconnect is located within the housing of the starter/generator.