Variable Spacer Reactor for Thermal Stress Reduction
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Solution Overview
Problem
In railroad vehicle reactors, the difference in linear expansion coefficients between the coil and the support frame causes thermal stress, leading to increased compression forces on the coil, which can reduce its reliability over time due to vibrations and temperature changes.
Innovation Solution
The reactor design incorporates a variable spacer with a first member and a second member, where the second member has a lower linear expansion coefficient, allowing it to adjust its length in response to temperature changes, thereby reducing the load on the coil by accommodating thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the coil is fixed to the support frame, then the coil is secured against vibrations, but thermal stress causes compression force on the coil due to difference in linear expansion coefficients
Solution Approach 1:
The spacer is designed with a variable length in the central axis direction that changes based on temperature. As temperature increases, the spacer lengthens to accommodate the thermal expansion of the coil, thereby maintaining a constant distance between adjacent unit coils and preventing compression forces on the coil insulation.
Solution Approach 2:
The spacer acts as an intermediary element between adjacent unit coils. It absorbs the dimensional changes caused by thermal expansion through its variable length mechanism, thereby mediating the interaction between coils and preventing direct compression contact that would harm the insulation.
2Ease of manufacture
If ferrous materials are used for the support frame and bolt, then material cost and ease of machining are improved, but the linear expansion coefficient differs from the coil material
Solution Approach 1:
The spacer's length parameter is made variable to compensate for the mismatch in linear expansion coefficients between the ferrous support frame and the aluminum/copper coil. This allows the system to maintain dimensional stability despite using cost-effective ferrous materials for the support structure.
3Stability of the object's composition
If the coil is insulated and fixed to reduce vibration load, then vibration resistance is improved, but thermal stress from temperature rise creates compression force
Solution Approach 1:
The spacer length in the central axis direction is designed to vary with temperature, increasing as temperature rises. This variable length mechanism compensates for thermal expansion of the coil, preventing the generation of compression forces that would otherwise occur when the coil expands against fixed insulation and support structures.
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 design effectively reduces the load on the coil due to thermal stress and vibrations, enhancing the long-term reliability of the reactor by minimizing thermal stress and maintaining optimal alignment between the coil and support frame.
Implementation Method 1
the linear expansion coefficient of the second member is less than the linear expansion coefficient of the first member... allowing it to adjust its length in response to temperature changes, thereby reducing the load on the coil by accommodating thermal expansion and contraction
Data Source
AI summary
A coil includes unit coils wound around a central axis and adjacent to each other with a space therebetween in a central axis direction. A reactor includes a pair of support frames and one or more spacers, the support frames facing each other in the central axis direction across the coil. The spacers are disposed between adjacent unit coils or between the support frame and the coil. At least one of the spacers is a variable spacer that includes a first member and a second member, the first member having one end face which has a recess, and the second member including a fitting portion to be fitted into the recess of the first member in the central axis direction. The linear expansion coefficient of the second member is less than the linear expansion coefficient of the first member.