Stator Support Radial Cut Reduces Hoop Stress
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Solution Overview
Problem
Electric machines in aircraft, such as starter/generators, face challenges in thermal expansion and contraction due to heating and cold soak cycles, leading to hoop stress issues that affect their operational reliability and efficiency.
Innovation Solution
A stator support design with a split support ring featuring radial cuts, allowing for increased radial displacement and reduced hoop stress, is integrated into the electric machine assembly. This design includes a core with conductive radial elements and insulators to form windings, and a heat conductive material frame and outer case for efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a continuous support ring is used in the stator support, then structural strength is improved, but thermal stress and hoop stress increase during heating and cold soak cycles
Solution Approach 1:
The support ring is divided into separate segments by introducing radial cuts, allowing each segment to independently expand and contract thermally while maintaining overall structural integrity. This segmentation reduces thermal stress and hoop stress during heating and cold soak cycles.
Solution Approach 2:
The structural parameters of the support ring are modified by introducing radial cuts that allow controlled radial displacement. This changes the mechanical behavior of the ring from rigid to flexible, enabling it to accommodate thermal expansion and contraction without excessive stress buildup.
2Manufacturing precision
If the support ring is made rigid to maintain structural integrity, then manufacturing precision is improved, but thermal expansion and contraction are restricted
Solution Approach 1:
The rigid continuous ring is segmented into multiple sections separated by radial cuts. Each segment maintains precise manufacturing tolerances while the gaps between segments allow for thermal expansion and contraction, providing both structural integrity and thermal adaptability.
Solution Approach 2:
The support ring transitions from a static rigid structure to a dynamic structure that can adapt its configuration in response to thermal conditions. The radial cuts enable the ring to flex and adjust radially during thermal cycling while maintaining overall structural integrity.
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 solution enhances the thermal management of electric machines by enabling a larger range of thermal conditions, reducing stress and improving operational reliability and efficiency during heating and cold soak cycles.
Implementation Method 1
a heat conductive material frame and outer case for efficient heat transfer
Implementation Method 2
allowing for increased radial displacement and reduced hoop stress... enabling a larger range of thermal conditions
Data Source
AI summary
A stator support 40 for an electric machine 10 includes a radial cut 70 in a support ring 46 that releases hoop stress in the support ring 46 and enables more radial displacement during heating and cold soak cycles in the stator 12, 16, thereby allowing a larger range of thermal conditions for the electric machine 10.