Integrated Accessory Gearbox Layout for Compact Turbine Engine Starting
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Solution Overview
Problem
The existing aircraft turbomachines face challenges in reducing the axial footprint of the accessory relay box, which is often too large for installation in compartments like the inter-vein or blower compartments.
Innovation Solution
Integrating the gearbox and freewheel for the turbomachine starter into the accessory relay housing, reducing the axial footprint by incorporating these components within the casing, and optimizing the shaft line and pinion configuration to balance load distribution and reduce space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the accessory relay box is equipped with a starter, gearbox, and freewheel as separate components, then the functional requirements are met, but the axial footprint becomes too large for installation in turbomachine compartments
Solution Approach 1:
The patent merges the starter, gearbox, and freewheel into a single integrated accessory relay box assembly. The starter motor (132) is positioned within the housing (102) with its pinion gear (134) directly engaged with the gearbox input shaft. The freewheel (124) is integrated into the same housing structure, receiving input from the gearbox output shaft. This consolidation eliminates the need for separate mounting brackets and support structures, reducing the overall axial footprint while maintaining all required functions.
Solution Approach 2:
The patent employs a nested arrangement where the starter motor (132) is positioned within the housing (102) space, and its pinion gear (134) nests into engagement with the gearbox input shaft. The freewheel (124) is nested within the same housing structure, with its drive shaft (126) receiving input from the gearbox output shaft. This nesting approach allows multiple components to occupy overlapping or adjacent spatial volumes, minimizing the external bounding box dimensions, particularly in the axial direction.
2Area of stationary object
If the accessory relay box is reduced in axial size, then installation space is freed, but the mechanical load distribution and component integration become more challenging
Solution Approach 1:
The patent segments the accessory relay box into distinct functional modules housed within a single housing (102). The starter motor (132) is positioned in a first region with its pinion gear (134) engaged with the gearbox input shaft. The gearbox (120) occupies a central region, with its output shaft driving the freewheel (124) in a second region. This segmentation allows each component to be optimized and potentially pre-assembled separately, then integrated into the final assembly, simplifying manufacturing while achieving compact dimensions.
Solution Approach 2:
The housing (102) serves multiple functions simultaneously: it provides structural support for all components, acts as a mounting bracket for the starter motor (132) and freewheel (124), serves as a protective enclosure, and facilitates load distribution through its rigid structure. The gearbox (120) serves dual purposes as both a speed reduction mechanism and a torque transmission element to the freewheel (124). This multi-functionality reduces the number of separate parts needed, easing manufacturing and assembly.
Data Source
Figure 1~2A
Figure 2B~3
Figure 4~5
AI summary
Accessory gearbox (50) for an aircraft turbine engine, comprising:• - a casing (52), • a reduction gear (62) and a freewheel (62) which are permanently integrated into the casing, the accessory gearbox being configured to interface with a starter (54) of the turbomachine that is intended to start up the turbomachine, the reduction gear and the freewheel being dedicated to the starter of the turbomachine.