Cryocooler Cold Head Mounting Structure for Stable Thermal Contact
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Solution Overview
Problem
The thermal contact between a cryocooler and a sleeve deteriorates over time due to the repeated maintenance process, leading to increased cooling temperatures and decreased efficiency, especially when an indium sheet is used for improved thermal contact.
Innovation Solution
A mounting structure and method that maintains thermal contact between the cryocooler and the sleeve by using a cold head accommodation sleeve to form an airtight region, with an inter-flange distance adjustment mechanism and a flange fastening mechanism to ensure physical contact under controlled thermal resistance, eliminating the need for an indium sheet and maintaining reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an indium sheet is used to improve thermal contact between the cold head and the sleeve, then the thermal contact is improved, but the thermal contact deteriorates over time due to repeated maintenance processes
Solution Approach 1:
The invention removes the indium sheet from the thermal contact interface between the cold head and the sleeve. By eliminating this intermediate material, the patent achieves direct thermal contact that maintains stable thermal properties over repeated maintenance cycles, solving the problem of thermal contact deterioration over time
Solution Approach 2:
The invention employs a flange fastening mechanism with adjustable pressing contact pressure that can be dynamically tightened to maintain optimal thermal contact. This dynamic adjustment capability ensures that thermal contact stability is preserved even after repeated maintenance operations, addressing the reliability-duration contradiction
2Ease of repair
If the cold head is heated to room temperature for maintenance work, then the maintenance work can be carried out, but the cooling target must be re-cooled which increases time required
Solution Approach 1:
The invention divides the system into separable components - the cold head can be detached from the sleeve via the flange connection mechanism. This segmentation allows the cold head to be independently heated for maintenance while the cooling target remains in place and can be quickly re-cooled by simply reattaching the cold head, significantly reducing the time loss
Solution Approach 2:
The flange fastening mechanism acts as an intermediary that enables easy separation and reconnection of the cold head. This mediator allows maintenance personnel to access the cold head for heating and servicing without permanently disconnecting the cooling system, facilitating quick re-assembly and rapid re-cooling of the target
3Reliability
If the pressing contact pressure between the cold head-side cooling stage and the sleeve-side cooling stage is increased to improve thermal contact, then the thermal resistance decreases, but the mechanical stress on the components increases
Solution Approach 1:
The invention optimizes the pressing contact pressure to a specific parameter range that achieves the desired thermal contact quality (thermal resistance below threshold) while staying within the mechanical stress limits of the components. This parameter optimization resolves the contradiction between thermal performance and mechanical strength
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 allows for long-term satisfactory thermal contact between the cryocooler and the sleeve, even after repeated maintenance, by managing the pressing contact pressure and thermal resistance, thus maintaining cooling efficiency and preventing thermal contact deterioration.
Implementation Method 1
The flange fastening mechanism fastens the cold head-side flange to the sleeve-side flange so that the cold head-side cooling stage is pressed against the sleeve-side cooling stage with a pressing contact pressure designated to bring the cold head-side cooling stage and the sleeve-side cooling stage into thermal contact with each other under thermal resistance equal to or smaller than a threshold
Implementation Method 2
a cold head accommodation sleeve that is installed in the vacuum vessel so as to form an airtight region isolated from an ambient environment between the cold head and the cold head accommodation sleeve
Data Source
AI summary
There is provided a mounting structure for mounting a cryocooler cold head on a vacuum vessel. The cold head includes a cold head-side cooling stage and a cold head-side flange. The mounting structure includes a cold head accommodation sleeve installed in the vacuum vessel and including a sleeve-side cooling stage which comes into thermal contact with the cold head-side cooling stage by coming into physical contact with the cold head-side cooling stage, and a sleeve-side flange to be coupled to the cold head-side flange, an inter-flange distance adjustment mechanism configured to adjust a distance between the sleeve-side flange and the cold head-side flange so that the cold head-side cooling stage and the sleeve-side cooling stage are physically brought into contact with each other or brought into a contactless state therebetween, and a flange fastening mechanism configured to fasten the cold head-side flange to the sleeve-side flange.