Insulated Splined Shaft Coupling With Axial Position Adjustment
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Solution Overview
Problem
In aircraft engine gearboxes, the driven shaft often fails to meet the required distance for preventing electrostatic discharge from accessories to the drive shaft, necessitating adjustments in the position of the drive shaft to comply with aerospace standards.
Innovation Solution
A rotatable shaft assembly featuring a splined coupling made of electrically-insulating material, coupled with a positioning device that allows axial displacement along the axis of rotation, enabling the adjustment of the splined coupling's position to maintain the necessary distance between the drive and driven shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driven shaft position is adjusted to meet the required distance for preventing electrostatic discharge, then the electrostatic discharge prevention is improved, but the driven shaft cannot meet the standard due to its fixed position capability
Solution Approach 1:
The invention makes the previously static driven shaft position adjustable by introducing a positioning device with adjustable mechanism. The driven shaft can now be dynamically repositioned along the axial direction to achieve the required distance for electrostatic discharge prevention, transforming a fixed configuration into an adjustable one.
Solution Approach 2:
The invention separates the positioning function from the driven shaft itself by introducing an independent positioning device. This segmentation allows the driven shaft to focus on its primary function while the positioning device handles the position adjustment, enabling the driven shaft to meet the distance standard without modifying its core structure.
2Reliability
If the drive shaft position is changed to meet the required distance, then the electrostatic discharge prevention is improved, but the device complexity increases due to additional positioning mechanisms
Solution Approach 1:
The invention introduces a positioning device as an intermediary component between the drive shaft and the driven shaft. This mediator handles the position adjustment function, allowing the driven shaft to be repositioned without requiring complex modifications to the drive shaft or the overall gearbox structure, thus managing complexity effectively.
Solution Approach 2:
The positioning device is designed to perform multiple functions: it positions the driven shaft axially, maintains the required distance for electrostatic discharge prevention, and allows for adjustable repositioning. This multi-functionality reduces the need for separate components, thereby managing device complexity while achieving the reliability goal.
3Reliability
If an electrically-insulating material is used for the splined coupling, then the electrostatic discharge prevention is improved, but the manufacturing precision requirements increase for ensuring proper coupling engagement
Solution Approach 1:
The invention uses electrically-insulating material for the splined coupling to prevent electrostatic discharge. While this material choice increases manufacturing precision requirements, the positioning device compensates for any dimensional variations, ensuring proper spline engagement between the coupling and the shafts, thus balancing the trade-off between material properties and manufacturing precision.
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
This solution effectively prevents electrostatic discharge by ensuring the required distance is maintained without altering the drive shaft's position, accommodating various lengths of driven shafts and adhering to aerospace standards, thus protecting the engine components.
Implementation Method 1
a splined coupling made of an electrically-insulating material
Data Source
AI summary
A shaft assembly for an aircraft engine includes a first shaft coupled to a second shaft with a splined coupling made of an electrically-insulating material. The first and second shafts and the splined coupling are rotatable about an axis. A positioning device is mounted to the splined coupling and to the first shaft about the axis. The positioning device is displaceable along the axis relative to the first shaft to vary an axial position of the splined coupling.