Seal Lip Thread Geometry for Early Screw Pumping Without Leakage
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Solution Overview
Problem
Conventional sealing devices with thread protrusions for screw pumping effect face issues of leakage during high-speed rotation due to gaps created by step-like design, and the screw pumping effect is not fully exhibited before sliding wear occurs.
Innovation Solution
The sealing device features a seal lip with first and second inclined surfaces equipped with thread protrusions, where the sidewalls of these protrusions are parallel to the shaft's center axis before sliding wear, eliminating gaps and enabling early-stage screw pumping effect without leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If thread protrusions are designed with a step structure to contact the shaft surface early, then the screw pumping effect is exhibited from an early stage, but gaps are created that cause fluid leakage during high-speed rotation
Solution Approach 1:
The patent applies curvature by replacing the conventional step structure with an inclined surface that gradually transitions from the base to the tip of the thread protrusion. This curved/inclined geometry eliminates the abrupt step gap while maintaining contact with the shaft surface, thereby preventing fluid leakage during high-speed rotation while still enabling early-stage screw pumping effect.
2Reliability
If thread protrusions are spaced away from the shaft surface to prevent gap formation, then leakage is inhibited, but the screw pumping effect is not fully exhibited in the early stage
Solution Approach 1:
The inclined surface provides a gradual transition that maintains continuous contact with the shaft surface without creating gaps. This curved geometry enables the thread protrusions to engage the shaft surface early in the rotation cycle, fully exhibiting the screw pumping effect from the outset while preventing fluid leakage through the elimination of step gaps.
3Productivity
If thread protrusions contact the shaft surface immediately, then screw pumping effect is maximized early, but high-speed rotation causes fluid to scatter through created gaps
Solution Approach 1:
The inclined surface of the thread protrusions eliminates the step structure that creates gaps during high-speed rotation. The gradual curvature allows the protrusions to maintain stable contact with the shaft surface, maximizing screw pumping efficiency while preventing fluid scattering that would otherwise occur through gap formation at high rotational speeds.
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 minimizes gaps between thread protrusions and the shaft, suppressing leakage and allowing the screw pumping effect to be exhibited from the outset, even before sliding wear occurs.
Implementation Method 1
thread protrusions that exhibit a screw pumping effect on an inclined surface of a lip end of a seal lip
Data Source
AI summary
Provided is a sealing device capable of exhibiting a screw pumping effect in an early stage while inhibiting leakage of a fluid to be sealed by providing thread protrusions. A second inclined surface is provided with a plurality of first thread protrusions that cause a fluid to be sealed to flow toward a region to be sealed when the seal lip rotates in one direction relative to a shaft, and a plurality of second thread protrusions that cause the fluid to be sealed to flow toward the region to be sealed when the seal lip rotates in another direction relative to the shaft. In a state before progress of sliding wear on the seal lip, a sidewall of each of the first thread protrusions on a side facing the region to be sealed and a sidewall of each of the second thread protrusions on the side facing the region to be sealed are both designed to be parallel to a center axis line of the shaft in a state in which the seal lip is in contact with a surface of the shaft.