Compliant Joint Drive Assembly for Dielectric Torque Isolation
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Solution Overview
Problem
In actuated ball valves, particularly in aircraft water supply systems, there is a need for a dielectric barrier to prevent electrical faults from the motor end from being transmitted to the metal ball shaft, while maintaining torque transmission, especially when the ball shaft is jammed or frozen, to avoid damage and ensure safe operation.
Innovation Solution
A dielectric insert is positioned between the drive shaft and the driven shaft, shaped to form an insulating layer with engagement features on both shafts, providing a dielectric barrier and ensuring torque transfer through a cross-shaped sleeve or cross-piece configuration, which can withstand short torque peaks and accommodate misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric barrier is introduced between the drive shaft and driven shaft, then electrical isolation is improved, but torque transmission capability deteriorates
Solution Approach 1:
A dielectric insert is introduced as an intermediary component between the drive shaft and driven shaft. This insert provides electrical isolation while still enabling torque transmission through its mechanical engagement features (keys, splines, or gear teeth) that transfer rotational force across the dielectric barrier.
Solution Approach 2:
The dielectric insert is made from composite materials or molded compounds that combine electrical insulation properties with sufficient mechanical strength to transmit torque. These materials allow the component to simultaneously provide electrical isolation and mechanical force transmission.
2Strength
If the ball shaft is made of metal to satisfy durability standards, then strength is improved, but electrical conductivity increases causing fault transmission
Solution Approach 1:
The drive train is segmented into separate components: a metal drive shaft for durability, a dielectric insert for electrical isolation, and a metal driven shaft for strength. This segmentation allows each component to be optimized for its specific function while preventing harmful electrical transmission.
Solution Approach 2:
The dielectric insert serves as a mediator between the metal drive shaft and metal driven shaft, allowing both to maintain their metal construction for durability while the insert blocks electrical fault transmission between them.
3Reliability
If a dielectric insert is added to the drive train, then electrical isolation is improved, but device complexity increases
Solution Approach 1:
Multiple functions are merged into the dielectric insert: electrical insulation, torque transmission through engagement features, and mechanical coupling between shafts. This consolidation reduces the need for separate components for each function, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The dielectric insert is designed as a multi-functional component that simultaneously provides electrical isolation and mechanical torque transmission, making it a universal element that addresses multiple requirements with a single component rather than requiring separate elements for each function.
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 dielectric insert effectively isolates the electric motor from the ball shaft, preventing electrical faults and ensuring reliable torque transmission, even under resistance, while maintaining the structural integrity and safety standards required for metal components.
Implementation Method 1
a dielectric insert arranged to be positioned between the drive shaft and the driven shaft, the insert assembly comprising a body of dielectric material shaped to form an insulating layer and configured to engage, respectively, with a first shaped engagement feature on the drive shaft and a second shaped engagement feature on the driven shaft
Data Source
AI summary
A torque transfer assembly comprising a drive shaft and a driven shaft and a dielectric insert arranged to be positioned between the drive shaft and the driven shaft, the insert assembly comprising a body of dielectric material shaped to form an insulating layer and configured to engage, respectively, with a first shaped engagement feature on the drive shaft and a second shaped engagement feature on the driven shaft, in torque transfer engagement, the insulating layer providing a dielectric barrier between the drive shaft and the driven shaft.