Composite Seal Structure for Low-Temperature Shaft Sealing
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Solution Overview
Problem
Existing seal structures using expanded graphite for low-temperature environments suffer from wear and contamination issues, while synthetic resin seals shrink at low temperatures, compromising sealing performance.
Innovation Solution
A seal structure comprising a synthetic resin first seal member with a shrinkage suppression part, such as an O-ring, and a second seal member made of expanded graphite, which has a lower shrinkage rate, is used to maintain close contact and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a gland packing made of expanded graphite is used, then sealing performance in low-temperature environments is improved, but wear and contamination occur
Solution Approach 1:
The seal structure is divided into two distinct seal members: a first seal member made of synthetic resin that contacts the shaft and provides low wear, and a second seal member made of expanded graphite that provides low-temperature sealing. Each material performs its optimal function in a segmented arrangement, resolving the contradiction between wear resistance and low-temperature performance.
Solution Approach 2:
The invention uses a composite seal structure combining two different materials (synthetic resin and expanded graphite) with complementary properties. The synthetic resin provides wear resistance while the expanded graphite provides low-temperature sealing, creating a composite system that achieves both requirements simultaneously.
2Object-generated harmful factors
If a seal ring made of synthetic resin is used, then wear and contamination are suppressed, but shrinkage occurs at low temperature
Solution Approach 1:
The seal function is segmented between two materials: synthetic resin for wear resistance and expanded graphite for low-temperature stability. The synthetic resin first seal member handles the wear-resistant function while the expanded graphite second seal member handles the low-temperature sealing function, eliminating the shrinkage problem.
Solution Approach 2:
The invention changes the material parameter (shrinkage rate) by selecting expanded graphite for the second seal member, which has a lower shrinkage rate than synthetic resin. This parameter change ensures that the sealing interface maintains contact at low temperatures despite the synthetic resin's tendency to shrink.
3Object-generated harmful factors
If the first seal member shrinks at low temperature, then a gap forms between the outer circumferential surface and the packing box, but using expanded graphite causes wear
Solution Approach 1:
The sealing system is segmented into two functional components: the first seal member made of wear-resistant synthetic resin and the second seal member made of dimensionally stable expanded graphite. This segmentation allows each material to optimize its properties without compromising the other.
Solution Approach 2:
The second seal member made of expanded graphite acts as an intermediary between the first seal member and the packing box. It compensates for the shrinkage of the synthetic resin first seal member by maintaining dimensional stability, thereby preventing gap formation while the first seal member provides wear resistance.
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 seal structure improves sealing performance in low-temperature environments by preventing wear and shrinkage, thereby enhancing the integrity of the seal.
Implementation Method 1
a shrinkage suppression part engaged with the annular groove of the first seal member and configured to suppress shrinkage of the first seal member in the radial direction at a low temperature
Implementation Method 2
an annular second seal member interposed between the first seal member and the outer sealing target surface and made of a material that has a lower shrinkage rate at a low temperature than the first seal member
Data Source
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AI summary
A seal structure (10) for sealing between a circumferential surface (2d) of a seal box (2) and an outer circumferential surface (50a) of a rotary shaft (50) that face each other includes: an annular first seal member (12) provided on a radially outer side of the outer circumferential surface (50a), having an annular groove (12a) that is open on one side in an axial direction, and made of a synthetic resin; a shrinkage suppression part (13) engaged with the annular groove (12a) of the first seal member (12) and configured to suppress shrinkage of the first seal member (12) in a radial direction at a low temperature; and an annular second seal member (14) interposed between the first seal member (12) and the outer circumferential surface (50a) and made of a material that has a lower shrinkage rate at a low temperature than the first seal member (12) and easily fits closely to the first seal member (12).