Toroidal Gearbox Layout for Compact Gas Turbine Accessory Drives
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Solution Overview
Problem
Existing gas turbine engine gearboxes face challenges in achieving a compact configuration that efficiently packages within the limited space between the engine core and nacelle, while ensuring effective mounting and accessibility of accessory drive components.
Innovation Solution
A gearbox configuration with all shaft portions parallel to each other and multiple drive gears in the same plane, where accessory drive components like air turbine starters, deoilers, and pumps are mounted on parallel surfaces, and driven by a common gear set including bevel gears, allowing for perpendicular orientation and reduced external line lengths, enhancing packaging and accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional gearbox configurations are used, then the gearbox can be mounted on the engine, but the space between the core nacelle and engine core is not efficiently utilized
Solution Approach 1:
The patent transitions from conventional linear or radial gear arrangements to a toroidal (doughnut-shaped) configuration where gears are arranged in a circular pattern around a central axis. This dimensional reorganization allows the gearbox to efficiently utilize the annular space between the engine core and nacelle, transforming the available three-dimensional space into a compact functional layout that reduces overall volume while maintaining accessibility.
Solution Approach 2:
The gearbox employs a curved toroidal housing with gears arranged in a circular arc rather than straight lines. This curvature allows the gearbox to conform to the annular mounting space, creating a compact configuration that fits within the curved boundaries of the engine-nacelle interface while reducing the bounding box volume compared to linear arrangements.
2Ease of operation
If accessory drive components are mounted on the gearbox, then drive operations are achieved, but service accessibility becomes difficult
Solution Approach 1:
The gearbox design segments the accessory drive components by mounting them on the external perimeter of the toroidal housing rather than embedding them within the gear train. This segmentation allows technicians to access and service individual components (such as fuel pumps, hydraulic pumps, and generators) from the outside of the gearbox assembly without disassembling the entire unit, thereby improving maintenance accessibility while preserving the compact toroidal form factor.
Solution Approach 2:
The toroidal housing itself serves as an intermediary structure that carries accessory drive components on its outer surface. This intermediate mounting surface allows components to be positioned away from the internal gear mechanisms while remaining structurally integrated with the gearbox, providing both compact packaging and external accessibility for servicing.
3Length of moving object
If external lines are routed traditionally, then connections are made, but line lengths are excessive
Solution Approach 1:
The patent merges the accessory drive component locations with the toroidal gearbox structure, positioning components on the housing perimeter in close proximity to their corresponding engine interfaces. This spatial merging allows external fluid and electrical lines to be routed directly from the gearbox perimeter to engine components, significantly reducing line lengths compared to traditional remote mounting arrangements while simplifying the overall routing geometry.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3C
AI summary
A gearbox (64) for a gas turbine engine (20) includes a housing (74) that includes a cavity (92) provided between opposing first and second mounting surfaces (76, 78). An input gear shaft is coupled to a drive gear (96, 98, 100). The drive gear (96, 98, 100) is connected to first and second shaft portions (114, 116) that respectively extend to the first and second mounting surfaces (76, 78). The first and second shaft portions (114, 116) and the drive gear are (96, 98, 100) coaxial with one another.