Seal Device Thread Groove Static Leakage
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Solution Overview
Problem
Conventional seal devices experience static leakage when the rotating shaft stops, as the centrifugal force is eliminated, causing sealing fluid to leak from the thread groove past the seal lip, leading to inefficiencies in fluid retention.
Innovation Solution
The seal device features a thread groove with a smaller cross-sectional area in the sliding contact area and a larger cross-sectional area on the inner peripheral side, preventing fluid flow during static conditions while enhancing fluid pumping action during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thread groove is provided on the seal flange to exert fluid pumping action during rotation, then sealing performance during rotation is improved, but static leakage occurs when the rotating shaft stops
Solution Approach 1:
The thread groove is designed with varying cross-sectional area along its length, creating different local properties: a smaller cross-sectional area in the sliding contact area to prevent fluid passage when static, and a larger cross-sectional area in the inner peripheral side area to maintain effective fluid pumping action during rotation. This local differentiation resolves the contradiction between static sealing and dynamic pumping performance.
2Ease of manufacture
If the thread groove has a constant cross-sectional area, then manufacturing is simplified, but fluid pumping efficiency is reduced and static leakage increases
Solution Approach 1:
The thread groove cross-sectional area is intentionally varied along its length rather than kept constant. The smaller cross-sectional area in the sliding contact region provides better static sealing, while the larger cross-sectional area in the inner peripheral side enhances fluid pumping efficiency during rotation, overcoming the limitations of a constant cross-section design.
Solution Approach 2:
The thread groove geometry is designed to adapt to different operational states: during rotation, the larger cross-sectional area in the inner peripheral side enables effective fluid pumping, while during static conditions, the smaller cross-sectional area in the sliding contact area prevents fluid leakage. This dynamic geometric adaptation resolves the trade-off between manufacturing simplicity and pumping efficiency.
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 effectively reduces static leakage and increases fluid pumping efficiency by controlling fluid flow, ensuring better sealing performance compared to constant cross-sectional thread grooves.
Implementation Method 1
a thread groove, which exerts a fluid pumping action with a centrifugal force at the time of rotation
Implementation Method 2
a seal lip attached to an inner periphery of the shaft hole of the housing is configured to come in sliding contact with a seal flange attached to an outer periphery of the rotating shaft
Data Source
AI summary
A seal device prevents sealing fluid on the inner-machine side from leaking to the outer-machine side between a housing and a rotating shaft inserted into a shaft hole on the housing. The seal lip is attached to the inner periphery of the shaft hole to slidingly contact the seal flange attached to the outer periphery of the rotating shaft. The thread groove, which exerts a fluid pumping action when the shaft is rotating, is provided on the seal flange so as to intersect with a lip end of the seal lip. The thread groove is formed so as to have a relatively small cross-sectional area in a sliding area in the seal flange that the seal lip comes in sliding contact with and have a relatively large cross-sectional area in an inner peripheral side area located on an inner peripheral side more than the sliding area.