Thermal-Contracting Card Rack for Cryogenic Clamping
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Solution Overview
Problem
Current circuit card rack systems face challenges in maintaining uniform clamping force and low thermal resistance at cryogenic temperatures, particularly due to the limitations of wedgelock systems which require same-material components, are complex, expensive, and prone to malfunction, leading to uneven clamping force and reduced thermal transfer.
Innovation Solution
A circuit card rack system with laterally oriented clamping slots made from temperature-contractible materials, where a predetermined temperature differential is applied to reduce the slot's longitudinal dimension, exerting compressive force on the circuit card, allowing for self-tightening and uniform contact pressure without the need for pre-tightening, and enabling different material combinations for improved thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If wedgelocks are used to maintain circuit cards in a card rack, then clamping force can be provided, but the system requires multiple small shims or wedges adding complexity and the wedgelocks are extremely expensive
Solution Approach 1:
The patent removes the complex wedgelock mechanism entirely and replaces it with a simple thermal expansion-based clamping system. The card rack uses a temperature-contractible material that naturally expands when cooled to provide clamping force, eliminating the need for multiple wedges, shims, and adjustment mechanisms.
Solution Approach 2:
The patent replaces the mechanical wedgelock system with a thermal-mechanical system. Instead of using mechanical wedges to provide clamping force, the system uses the thermal expansion properties of a temperature-contractible material that expands when cooled to cryogenic temperatures, automatically providing uniform clamping force without mechanical adjustment components.
2Force
If wedgelocks are used to maintain circuit cards in a card rack, then clamping force can be provided, but multiple wedgelocks are needed which increases cost significantly
Solution Approach 1:
The patent merges the clamping function into the card rack structure itself. Instead of using separate wedgelocks at discrete locations, the entire card rack is made from a temperature-contractible material that provides continuous clamping force along the entire card slot when cooled, eliminating the need for multiple discrete clamping components.
Solution Approach 2:
The temperature-contractible card rack serves multiple functions simultaneously: it provides structural support, thermal conduction, and clamping force. The single component performs what previously required multiple specialized components (wedgelocks, shims, mounting structures), reducing both quantity and complexity.
3Force
If wedgelocks are used to maintain circuit cards in a card rack, then clamping force can be provided, but there are local high/low clamping force areas along the length of the card slot
Solution Approach 1:
The patent creates uniform clamping force distribution by making the entire card rack structure from a temperature-contractible material. This ensures that every point along the card slot experiences the same thermal expansion and clamping force when cooled, eliminating local variations that occur with discrete wedgelocks at specific locations.
Solution Approach 2:
The patent provides continuous clamping force along the entire length of the card slot through the thermal expansion of the temperature-contractible material. Unlike discrete wedgelocks that create intermittent clamping at specific points, the continuous material expansion ensures uniform and continuous contact pressure throughout the entire card-rack interface.
4Force
If wedgelocks are used to maintain circuit cards in a card rack, then clamping force can be provided, but thermal transfer between modules and card rack is reduced due to noncontiguous placement
Solution Approach 1:
The patent creates a continuous thermal pathway by making the entire card rack from a temperature-contractible material that maintains continuous contact with the circuit card. This eliminates the thermal breaks created by discrete wedgelocks, allowing efficient heat conduction from the card through the entire length of the rack structure.
Solution Approach 2:
The patent uses a temperature-contractible material with appropriate thermal conductivity properties to achieve both mechanical clamping and thermal conduction functions simultaneously. The material composition is selected to provide the desired thermal performance while maintaining the clamping force through thermal expansion at cryogenic temperatures.
5Temperature
If same-material components are used for card rack and module to achieve desired thermal conductivity, then thermal performance is improved, but material selection is limited
Solution Approach 1:
The patent changes the thermal state parameter by using a temperature-contractible material that exhibits different dimensional properties at different temperatures. This allows the card rack to be made from materials optimized for cryogenic performance while the thermal expansion behavior at low temperatures provides the clamping force, decoupling the thermal conductivity requirement from the clamping mechanism requirement.
Solution Approach 2:
The patent enables different material combinations by using a temperature-contractible material for the card rack structure that can be paired with various card materials. The thermal expansion properties of the rack material provide clamping force independent of the card material, allowing optimization of each component for its specific function while maintaining good thermal contact.
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 system achieves consistent and efficient clamping force and enhanced thermal performance by utilizing thermal expansion of the clamping slot to maintain circuit cards, reducing the need for multiple wedgelocks and ensuring uniform contact pressure across the card slot, while allowing for different material combinations to improve thermal conductivity.
Implementation Method 1
A predetermined temperature differential is applied to the clamping slot to reduce a longitudinal dimension of at least a portion of the clamping slot. A compressive force is exerted on the portion of the clamped side region which is located longitudinally within the clamping slot, via thermal expansion of the clamping slot.
Implementation Method 2
The clamping slot is at least partially formed from a temperature-contractible material. A compressive force is exerted on the portion of the clamped side region which is located longitudinally within the clamping slot, via thermal expansion of the clamping slot.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A method of maintaining a circuit card in a card rack and a circuit card rack system are disclosed. A card rack including a laterally oriented clamping slot is provided. The clamping slot is at least partially formed from a temperature-contractible material. A circuit card having a clamped side region is provided. At least a portion of the clamped side region is inserted into the clamping slot. A predetermined temperature differential is applied to the clamping slot to reduce a longitudinal dimension of at least a portion of the clamping slot. A compressive force is exerted on the portion of the clamped side region which is located longitudinally within the clamping slot, via thermal expansion of the clamping slot.