Dual Drive Path Generator with Shear Section
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Solution Overview
Problem
The existing dual coaxial or concentric drive shaft configuration for generators is inadequate in protecting the gearbox from mechanical failures, as the outer drive shaft is unstable and cannot adequately support the inner drive shaft, limiting its diameter and stability.
Innovation Solution
A generator arrangement with a dual drive path and a shear section that supports a hollow rotor shaft, where lubricating fluid is pressurized by centrifugal forces and used to lubricate bearings, ensuring the permanent magnet generator remains functional despite main generator failures, and includes a shear section in the drive shaft to prevent overload damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a dual coaxial drive shaft configuration is used to combine EEC PMG and main generator on a single drive pad, then the accessory drive pad count is reduced, but the outer drive shaft becomes unstable and cannot adequately protect the gearbox from mechanical failures
Solution Approach 1:
The drive shaft system is segmented into an outer drive shaft and an inner drive shaft that are mechanically independent. The outer drive shaft connects to the EEC PMG while the inner drive shaft connects to the main generator, allowing one shaft to fail without affecting the other. This segmentation resolves the contradiction by enabling both generators to share a single drive pad while maintaining independent failure paths that protect the gearbox.
Solution Approach 2:
The outer drive shaft acts as an intermediary protective element between the gearbox and the main generator. It is designed with a shear section that can fail under overload conditions, absorbing the mechanical stress and preventing damage to the gearbox and the inner drive shaft. This intermediary structure enables reliable gearbox protection while maintaining the compact dual-generator configuration.
2Stability of the object's composition
If the outer drive shaft is made stronger to support the inner drive shaft, then the structural stability improves, but the shear section strength becomes too great to adequately protect the gearbox from overload
Solution Approach 1:
The outer drive shaft exhibits local quality variation through its structured design: it has reinforced sections for structural stability and support, but also includes a deliberately weakened shear section with reduced cross-sectional area. This local quality differentiation allows the shaft to be stable enough to support the inner drive shaft while having a specific weak point that will fail first under overload, protecting the gearbox.
Solution Approach 2:
The outer drive shaft's cross-sectional parameters are changed along its length, creating a shear section with reduced dimensions compared to other portions of the shaft. This parameter change creates a controlled weak point that fails at a lower torque threshold than the rest of the shaft or the gearbox, enabling overload protection while maintaining overall structural integrity for normal operation.
3Stability of the object's composition
If the outer drive shaft is made larger to increase stability, then the support capability improves, but the inner diameter is limited by the maximum outer diameter of the inner drive shaft
Solution Approach 1:
The inner drive shaft is nested within the outer drive shaft, with the inner shaft positioned coaxially inside the outer shaft's hollow interior. This nesting arrangement allows the outer drive shaft to have a larger outer diameter for improved stability and strength without interfering with the inner drive shaft's dimensions. The hollow cross-section of the outer shaft provides structural rigidity while accommodating the inner shaft, resolving the spatial constraint.
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
Enhances the reliability of the permanent magnet generator by isolating it from main generator failures and providing effective lubrication and cooling, ensuring continuous power supply even under overload conditions.
Implementation Method 1
a lubricating fluid passes through passages in a housing of the single generator and into the hollow portion of the rotor shaft where the lubricating fluid is pressurized by the centrifugal forces resulting from rotation
Data Source
AI summary
A generator arrangement is provided in which the functionality of two typically separate electrical power generators are combined together into a single generator that forms part of a three-in-one combined multi-generator which has a dual drive path with a shear section that immunizes one of the generators (e.g., the permanent magnet generator) within the single combined multi-generator from a failure of another generator (e.g., the main generator) within the single combined multi-generator.