Sealing Device With Opposing Thread Ridges
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Solution Overview
Problem
Conventional sealing devices with thread ridges on the seal lip experience leaks due to scraping actions during the rotation of a rotating body, as the oblique thread ridges on one side cause a slight scraping action on the oil film, leading to potential leakage.
Innovation Solution
The sealing device features a lip-edge portion fitted into the inner circumference surface of a rotating body, with first and second thread ridges extending obliquely in opposite directions, and a circumferential ridge intersecting them, which initiates forward and reverse screw-pump actions to push back and return fluid, effectively preventing leaks by directing the fluid along the circumferential ridge back to the sealed space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oblique thread ridges are formed on the seal lip to achieve screw-pump action, then sealing performance is improved, but scraping action on the oil film increases causing potential leakage
Solution Approach 1:
The thread ridge is segmented into multiple ridges (first thread ridge and second thread ridge) with different orientations. The first thread ridge has an oblique angle for screw-pump action, while the second thread ridge has a smaller oblique angle to reduce scraping. This segmentation allows each ridge to perform its specific function without the harmful effects of a single aggressive ridge.
Solution Approach 2:
Different portions of the seal lip are given different ridge configurations. The first thread ridge portion provides strong screw-pump action where needed, while the second thread ridge portion provides reduced scraping action. This local differentiation of ridge properties resolves the contradiction between effective sealing and minimal harmful scraping.
2Ease of manufacture
If thread ridges are made with constant width and height to simplify manufacturing, then ease of manufacture is improved, but scraping action increases causing leaks
Solution Approach 1:
The ridge structure is divided into multiple segments (first and second thread ridges) with different geometric parameters. This segmentation allows each ridge to be optimized for its specific function while maintaining manufacturability through standardized formation processes for each ridge type.
Solution Approach 2:
The first and second thread ridges are designed with asymmetric properties - different oblique angles and orientations. This asymmetry enables each ridge to perform its specific function (strong screw-pump vs. reduced scraping) while both can be manufactured using consistent processes, balancing manufacturing ease with functional reliability.
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 prevents leaks by using the circumferential ridge to dam and redirect fluid, ensuring that oil is pushed back to the sealed space, regardless of the rotating direction, thereby maintaining effective sealing functionality.
Implementation Method 1
both of the first thread ridges 104 and the second thread ridges 105 attain screw-pump action in a forward direction to the rotation of the rotating shaft 200
Implementation Method 2
the lip-edge portion 101 of an inner diameter of the seal lip 100, fitted into the inner circumference surface of a housing, not shown in the drawing, closely fitted to be able to slide on an outer circumference surface of a rotating shaft 200
Data Source
AI summary
A sealing device with a lip edge portion 2a and a sealing-space-opposite-side conical surface 2b whose diameter increases from the lip edge portion 2a toward a sealing space B opposite side is formed on an inner peripheral surface of a seal lip 2, and a first thread ridge 21 that obliquely extends in a given direction with respect to a circumferential direction, a second thread ridge 22 that obliquely extends in a direction opposite to the direction in which the first thread ridge 21 obliquely extends, and a circumferential ridge 23 that extends in the circumferential direction while intersecting the first thread ridge 21 and the second thread ridge 22 are formed on the sealing-space-opposite-side conical surface 2b.