Probe Feedthrough Sealing with Tapered Aluminum Bushing
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Solution Overview
Problem
Conventional feedthroughs face challenges in maintaining a seal due to thermal expansion and contraction, material fatigue, and physical disturbances, leading to leaks and loss of sealing function, especially when probes are made of soft materials and subjected to temperature cycling or repositioning within vacuum chambers.
Innovation Solution
A feedthrough device comprising a gland body and a seal device with a bushing made of aluminum and a washer, featuring a tapered design and a ring seal, which provides a secure seal across a vacuum chamber from atmospheric pressure to below-atmospheric pressure, using dissimilar metals to enhance reusability and sealing capabilities without the need for lubricants, and includes a channel for compliance and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal is compressed to achieve sealing function, then sealing effectiveness is improved, but the probe's cross-sectional shape is progressively reduced or modified by temperature cycling, resulting in loss of sealing function
Solution Approach 1:
The feedthrough device is divided into distinct functional segments: a rigid gland body for structural support, a compliant seal member for sealing, and a probe for signal transmission. This segmentation allows each component to perform its specific function without compromising the others, particularly protecting the soft probe from direct compressive forces that would deform its cross-section.
Solution Approach 2:
A seal member acts as an intermediary between the rigid gland body and the soft probe. This seal member absorbs the compressive forces and thermal expansion/contraction stresses, preventing direct transmission of these forces to the probe and thereby maintaining the probe's cross-sectional integrity while still achieving effective sealing.
2Reliability
If dissimilar metals are used in the seal device, then reusability and sealing capabilities are enhanced, but thermal expansion differences cause relative movement between components, degrading sealing function
Solution Approach 1:
The seal member is designed with specific material parameters (softer, more compliant) that allow it to accommodate thermal expansion differences between dissimilar metals. Its compliance enables it to maintain sealing contact despite relative movement caused by differential thermal expansion of the aluminum bushing and stainless steel gland body.
Solution Approach 2:
The seal device utilizes a composite structure combining aluminum (bushing) and stainless steel (gland body) with a specialized seal member material that bridges these dissimilar metals. This composite approach leverages the advantages of each material while the compliant seal member compensates for their thermal expansion mismatches.
3Adaptability or versatility
If a probe is repositioned or adjusted physically, then measurement or control capability is improved, but sealing function is lost due to displacement or deformation of the probe
Solution Approach 1:
The seal member is designed with dynamic compliance, allowing it to adapt its shape and position as the probe moves. This dynamic sealing capability enables probe repositioning while maintaining the seal, unlike rigid sealing arrangements that would fail upon probe displacement.
Solution Approach 2:
The seal member functions as a flexible sealing element that can deform and conform to the probe's position changes. This flexibility allows the seal to maintain its sealing function even when the probe is repositioned or adjusted within the feedthrough.
4Duration of action of stationary object
If friction is reduced to minimize wear, then component longevity is improved, but sealing effectiveness may be compromised
Solution Approach 1:
The seal member's material parameters are optimized to provide sufficient friction for effective sealing while limiting wear. Its compliance and elastic properties allow it to maintain sealing contact without requiring high friction forces, thereby reducing wear and extending component life.
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 effectively maintains a leak-tight seal during thermal processes and repositioning of probes, reducing the need for frequent component replacement and ensuring reliable sealing across a wide range of temperatures and pressures, while minimizing friction and wear.
Implementation Method 1
a seal device disposed between the gland body and a second surface of the wall body, wherein the seal device comprises: a bushing having a tapered outside diameter that contacts a tapered surface of the gland body
Implementation Method 2
A problem is that material properties of components forming the seal may change as a result of the expansion and contraction of the seal components and/or material fatigue
Implementation Method 3
components of the feedthrough and the probe, which may be a rod-shaped probe, may have different thermal expansion coefficients, or be exposed to different levels of heat, and therefore expand and contract differently
Implementation Method 4
A related problem is a loss of elasticity of components forming the seal, thereby allowing leaks to form as thermal expansion and contraction modify the seal's geometry
Data Source
Figure 1A~1C
Figure 2A~2C
AI summary
Embodiments of the disclosure provide methods and apparatus for a feedthrough. In one embodiment, a feedthrough includes a gland body having an opening formed therethrough along a longitudinal axis thereof, the gland body being adapted to mate with a threaded opening formed in a wall body at a first surface thereof, and a, seal device disposed between the gland body and a second surface of the wall body, wherein the seal device comprises a bushing having a tapered outside diameter that contacts a tapered surface of the gland body, a washer having a first surface that contacts a surface of the bushing, and a ring seal contacting a second surface of the washer and an internal surface of the wall body.