Propeller Shaft Support Assembly for Turbo Propeller Engine
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Solution Overview
Problem
Increasing the bearing span in turbo propeller engines to reduce load transmission to the housing results in increased engine length, which negatively impacts performance.
Innovation Solution
A support assembly for the propeller shaft with bearings positioned on opposite sides of the gearbox, allowing for an increased bearing span without extending the engine length, utilizing a planetary gear train and strategically placing bearings to counteract radial and axial load components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the bearing span is increased to reduce load transmission to the housing, then the load on the housing is reduced, but the overall length of the gas turbine engine increases
Solution Approach 1:
The patent positions the second bearing on the opposite side of the gearbox rather than extending it forward, utilizing the axial space behind the gearbox to increase the bearing span in the axial direction without increasing the engine's overall length. This dimensional repositioning allows the bearing span to be extended while maintaining a compact engine footprint.
Solution Approach 2:
The second bearing is nested within the existing engine structure by positioning it between the housing and the gearbox component, effectively utilizing the space already allocated for the gearbox. This nesting approach allows the bearing to be positioned optimally for load reduction without requiring additional external space that would increase engine length.
2Strength
If the bearing span is increased to reduce housing load, then the structural load is reduced, but the engine length and complexity increase
Solution Approach 1:
The second bearing positioned on the opposite side of the gearbox serves multiple functions: it supports the propeller shaft, reduces load on the housing, and is integrated with the gearbox structure. This multi-functional positioning reduces the need for separate support structures, thereby limiting the increase in device complexity despite the increased bearing span.
Solution Approach 2:
The patent combines the second bearing with the existing gearbox structure, merging the support function into the already-present component. This integration approach allows the bearing to be positioned optimally for load reduction while avoiding the need for separate, additional support structures that would increase overall system complexity.
Data Source
AI summary
A turbo propeller engine comprises a housing circumferentially extending around a longitudinal axis and disposed around a gearbox. The turbo propeller engine includes a propeller outside of the housing and a shaft surrounded in part by the housing and extending along the longitudinal axis. The shaft has a front end and a rear end. The propeller is mounted to the front end. The rear end is in a driven engagement with an output of the gearbox. The shaft is rotatably supported by a first bearing and by a second bearing separated from the first bearing by an axial distance along the longitudinal axis. The first and second bearings are disposed on opposite sides of the gearbox. The first bearing is disposed between the shaft and the housing, the second bearing is disposed between the housing and a component of the gearbox to rotatingly support the component of the gearbox.