NMR Probe Dual O-Ring Sealing for Low-Temperature Vacuum
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Solution Overview
Problem
Existing NMR measuring probes face challenges in enlarging the temperature adjustment range of temperature adjustment gases without deteriorating the vacuum degree, particularly due to the embrittlement of sealing members at low temperatures and high gas permeability at regular temperatures, which limits the lower limit of the temperature adjustment range.
Innovation Solution
The use of a dual sealing structure comprising a high-vacuum O-ring made of fluorinated rubber for regular temperatures and a low-temperature O-ring made of silicone rubber, where the low-temperature O-ring has a lower embrittlement temperature than the high-vacuum O-ring, allowing for effective sealing in both temperature regions to maintain a high vacuum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sealing member made of rubber material is used to seal the gas pipe, then assembly ease and adjustment ease are improved, but the lower limit of temperature adjustment range cannot be lowered without deteriorating vacuum degree due to embrittlement and gas permeability
Solution Approach 1:
The sealing structure is segmented into multiple sealing members with different material characteristics. The first sealing member (fluorinated rubber) provides low gas permeability for regular temperatures, while the second sealing member (silicone rubber) provides low embrittlement for low temperatures. This segmentation allows each sealing member to specialize in different temperature ranges, resolving the contradiction between assembly ease and temperature range limitation.
Solution Approach 2:
The sealing structure uses composite sealing members made from different rubber materials (fluorinated rubber and silicone rubber) with complementary properties. By combining materials with different embrittlement temperatures and gas permeability characteristics, the sealing structure achieves both ease of assembly and extended temperature adjustment range without compromising vacuum degree.
2Adaptability or versatility
If the temperature adjustment range is enlarged by lowering the lower limit, then temperature control flexibility is improved, but vacuum degree deteriorates due to sealing member embrittlement and gas permeability
Solution Approach 1:
The sealing function is segmented across multiple sealing members positioned at different locations in the sealed section. The first sealing member maintains vacuum integrity at regular temperatures through low gas permeability, while the second sealing member maintains integrity at low temperatures through low embrittlement. This segmentation enables extended temperature adjustment range while preserving vacuum degree reliability.
Solution Approach 2:
Different sealing members are positioned at specific locations within the sealed section based on their material characteristics. The first sealing member (low gas permeability) is positioned to handle regular temperature conditions, while the second sealing member (low embrittlement) is positioned to handle low temperature conditions. This local quality assignment optimizes the sealing performance across the entire temperature range without compromising vacuum degree.
3Device complexity
If a single sealing member is used to seal the gas pipe, then device complexity is reduced, but the temperature adjustment range is limited due to material embrittlement at low temperatures
Solution Approach 1:
The sealing structure is divided into multiple sealing members with distinct material properties. The first sealing member uses fluorinated rubber for low gas permeability at regular temperatures, while the second sealing member uses silicone rubber for low embrittlement at low temperatures. This segmentation increases temperature adjustment range from -40°C to -80°C or lower, outweighing the moderate increase in sealing structure complexity.
Solution Approach 2:
The sealing structure employs composite sealing members made from different rubber materials with complementary properties. By combining fluorinated rubber (low gas permeability) and silicone rubber (low embrittlement), the sealing structure achieves both simplicity and extended temperature range, resolving the contradiction between device complexity and temperature adjustment range.
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 configuration enables a broader temperature adjustment range without compromising the vacuum degree, allowing for lower sample temperatures while maintaining high vacuum conditions, thus enhancing the operational flexibility of the NMR measuring probe.
Implementation Method 1
a first sealing member (58) having characteristics for sealing the sealed section in a regular temperature region excluding a low temperature region, and a second sealing member (60) that is provided on a vacuum side or an atmosphere side to the first sealing member (58) in the sealed section and has characteristics for sealing the sealed section in the low temperature region in the temperature adjustment range
Implementation Method 2
a second sealing member (60) that is provided on a vacuum side or an atmosphere side to the first sealing member (58) in the sealed section and has characteristics for sealing the sealed section in the low temperature region in the temperature adjustment range
Data Source
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AI summary
A sample tube (50) is arranged in a sample temperature adjusting pipe, and a temperature adjustment gas is supplied. A vacuum vessel (28) is formed with the sample temperature adjusting pipe (24) and an outer wall body (26), and a detection coil (52) to be placed in a cooling state are arranged in the vacuum vessel. A sealed section between the sample temperature adjusting pipe and the outer wall body is sealed by a sealing structure. The sealing structure includes a high-vacuum O-ring (60) and a low-temperature O-ring (58). The high-vacuum O-ring has characteristics for sealing the sealed section in a regular temperature region. The regular temperature region is a temperature region excluding a low temperature region, and the low temperature region is a temperature region including a lower limit in a possible temperature adjustment range of the temperature adjustment gas. The low-temperature O-ring has characteristics for sealing the sealed section in the low temperature region.