Rotor Axial Retaining Structure for Coil Head Thermal Expansion
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Solution Overview
Problem
Rotatory electric machines with wound rotors face issues of uncontrollable thermal expansion leading to coil head displacement and potential structural damage, either from excessive movement or restricted space, which can cause coil slumping.
Innovation Solution
An axial retaining device with a substantially flat base and resilient elements is integrated into the rotor, allowing controlled freedom for axial displacement of the coil head during expansion, utilizing lashing straps and insulating composite materials to absorb movement and maintain coil integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid structural limiter is used to constrain coil head expansion, then the coil head displacement is controlled, but the space for thermal expansion becomes insufficient causing structural damage to the rotor
Solution Approach 1:
The patent applies the dynamics principle by replacing the rigid structural limiter with a resilient member that provides dynamic, adaptable constraint. The resilient member can deform elastically under thermal expansion forces, allowing the coil head to expand while maintaining controlled displacement. This dynamic response prevents structural damage while accommodating thermal growth, resolving the contradiction between displacement control and structural integrity.
Solution Approach 2:
The patent utilizes parameter changes by employing a resilient member with specific elastic properties that change under thermal loading. The resilient member's stiffness and deformation characteristics are designed to accommodate thermal expansion parameters while maintaining mechanical constraint. This allows the system to adapt its mechanical properties based on thermal conditions, preventing both excessive displacement and structural damage.
2Temperature
If no structural limitation is provided for coil head expansion, then the coil head has freedom to expand thermally, but the coil head moves excessively in the axial direction causing turns of the coil to slump
Solution Approach 1:
The patent applies the intermediary principle by introducing a resilient member as a mediator between the coil head and the rigid rotor structure. This resilient member serves as a buffer that allows thermal expansion while preventing excessive axial movement. The intermediary absorbs the contradiction between thermal freedom and positional stability, maintaining coil turn integrity while accommodating temperature-induced expansion.
3Stability of the object's composition
If a rigid structural limiter is used to constrain coil head expansion, then the coil head displacement is controlled, but the device complexity increases due to additional structural components
Solution Approach 1:
The patent applies the flexible shell principle by using a resilient member that functions as a flexible constraint element. This resilient member provides the necessary mechanical constraint in a simplified form compared to rigid structural limiters. The flexible nature of the resilient member allows it to accommodate thermal expansion while maintaining positional control, reducing overall device complexity while achieving the desired stability.
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 axial retaining device effectively manages axial expansion, preventing coil slumping while maintaining structural integrity by providing controlled displacement and resilience to absorb thermal expansion, ensuring stable operation of the rotatory electric machine.
Implementation Method 1
at least one resilient member attached to a face of the substantially flat base facing in a direction opposite to said one of the two coil head regions. The at least one resilient element is in contact with the corresponding support disc
Implementation Method 2
The operation of the electric machine causes a rise in temperature of the assembly, which, in turn, can lead to thermal expansion of the coil head
Data Source
AI summary
A rotor for a rotary electric machine is provided, with a pack of plates mounted on a shaft, in which said pack of plates has two coil head regions, the rotor having at least one axial retaining device positioned in one of the two coil head regions; the axial retaining device includes a substantially flat base positioned in said one of the two coil head regions and at least one resilient element fastened to a face of the substantially flat base oriented in a direction opposite said one of the two coil head regions.