Hermetic Sealing Device Thread Curvature
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Solution Overview
Problem
Hermetic sealing devices with stepped threads suffer from instability due to angle changes and increased risk of dust infiltration and oil leakage, as the stepped design narrows the space between the shaft and the sealing lip, allowing dust to enter and compromise sealability.
Innovation Solution
A hermetic sealing device with a thread that features a large curve on the atmosphere side sliding surface, connecting a low projecting section to a high projecting section, where the thread height gradually increases and widens from the lip tip, forming a linear ridge line, eliminating angle instability and maintaining a consistent space with the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stepped thread design is used to maintain sealability during wear, then the thread height increases to strengthen the pumping effect, but the space between the shaft and sealing lip becomes narrow, increasing dust infiltration risk
Solution Approach 1:
The atmosphere side sliding surface is formed with a large curve (arc shape) instead of straight lines or stepped surfaces. This curved surface allows the thread height to gradually increase from the lip tip toward the base, maintaining sealability during wear while avoiding the creation of narrow spaces that would trap dust particles.
Solution Approach 2:
The thread height parameter is varied continuously along the atmosphere side sliding surface, transitioning from lower height at the lip tip to higher height at the base. This gradual parameter change ensures that the thread maintains contact with the shaft during wear while the curved surface geometry prevents dust accumulation zones.
2Power
If a stepped thread with angle changes is used, then the pumping effect is strengthened, but angle instability occurs and dust guidance increases
Solution Approach 1:
The large curve (arc) formed by the atmosphere side sliding surface creates a smooth, continuous transition in the thread geometry. This curved configuration eliminates abrupt angle changes while maintaining the progressive increase in thread height, thereby preserving pumping effect without creating unstable angle transitions that would guide dust.
3Reliability
If thread height is increased to compensate for wear, then sealability is maintained, but the space between component surfaces is reduced, allowing dust entry
Solution Approach 1:
The arc-shaped atmosphere side sliding surface creates a gradual, curved transition zone that increases thread height while maintaining adequate clearance between the sealing lip and shaft. The curvature distributes the height increase over a larger area, preventing the formation of narrow gaps where dust could accumulate.
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 design enhances seal stability by preventing dust infiltration and maintaining seal integrity, as the linear ridge line and curved surface prevent dust guidance and ensure consistent sealing performance even with wear, significantly extending the time to oil leakage.
Implementation Method 1
a pumping effect achieved by the thread projection
Implementation Method 2
an oil seal with a screw
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
[Configuration] In a hermetic sealing device provided with a thread on an atmosphere side sliding surface of a sealing lip that is in sliding contact with a rotating shaft, the atmosphere side sliding surface of the sealing lip is formed into a large curve that passes a sealing lip tip and recedes from a surface of a component with which the lip is in sliding contact towards the atmosphere side. A thread with a triangular cross-section is formed connecting the lip tip to a projecting section of a predetermined height formed at a required position distant from the lip tip. A ridge line of a thread peak of the thread is formed linearly. A thread is formed on the atmosphere side sliding surface, configured such that the height of the thread peak gradually increases away from the lip tip. [Effect] Because the ridge line of the thread peak is linear, a space between the shaft and the sealing lip can be maintained. As a result, risk of infiltrating dust being guided to a contacting section of the sealing lip tip can be suppressed, and leakage caused by dust becoming caught in the sealing lip can be prevented.