Windage Cover Structure for Ring Gear Fastener Shear Losses
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Solution Overview
Problem
In gas turbine engines, the lubrication fluid centrifuged outwardly due to high rotational speeds interferes with the rotation of fasteners in the power gearbox, leading to shear losses and reduced efficiency, particularly at interrupted bolted flange geometries.
Innovation Solution
A windage cover, either 'L' shaped or with spring-like features, is implemented to cover the fasteners coupling the ring gear assembly to the output shaft, providing radial and axial retention without using fasteners, thereby reducing shear losses and maintaining assembly integrity under centrifugal forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fasteners are used to couple the ring gear assembly to the output shaft, then assembly integrity is maintained, but shear losses increase due to lubrication fluid interference with fastener rotation
Solution Approach 1:
The patent extracts the fasteners from the system by using a windage cover that shields the fastener locations, removing the source of shear losses while maintaining assembly integrity through alternative retention methods
Solution Approach 2:
The windage cover acts as an intermediary element that covers the fasteners and prevents lubrication fluid from reaching them, thereby eliminating the harmful interaction between fluid and fastener rotation
2Reliability
If the windage cover is retained using fasteners, then the cover is securely attached, but the number of fasteners increases adding complexity
Solution Approach 1:
The patent replaces the mechanical fastening system with a centrifugal retention system where the windage cover is held in place by centrifugal force generated during rotation, eliminating the need for additional fasteners
Solution Approach 2:
The windage cover utilizes the rotational motion of the gearbox itself to generate centrifugal force that retains the cover in place, allowing the system to secure itself without additional fastening components
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 windage cover effectively reduces shear losses and maintains assembly integrity by providing a radial shield and axial preload, enhancing the efficiency and reliability of the gearbox operation by minimizing the interaction between lubrication fluid and fasteners.
Implementation Method 1
The integral lip of the output shaft is configured to retain radially the windage cover during rotation of the output shaft
Implementation Method 2
the lubrication fluid centrifuged outwardly due to high rotational speeds
Data Source
AI summary
A windage cover for a plurality of fasteners coupling a ring gear assembly to an output shaft. The windage cover includes a clip retention member abutting an integral cover shell of the output shaft, and a foot portion configured to be inserted into a pilot groove between an integral lip and an arm portion of the output shaft. The windage cover also includes a wall portion connected to the foot portion, the wall portion being retained at one end of the wall portion by the clip retention member. The windage cover is configured to cover the plurality of fasteners.