Seal Lip Protrusion Structure for Garter Spring Retention
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Solution Overview
Problem
The disengagement of a garter spring from an annular groove in sealing devices, particularly in fluororubber materials, is a common issue during transportation and assembly, leading to potential damage and limitations in manufacturing processes.
Innovation Solution
A sealing device with a suppression part comprising protrusion parts and release grooves on the seal lip, which support and restrain the garter spring, preventing its disengagement and reducing undercut regions during mold release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the region where the garter spring is supported by the annular groove is increased to prevent disengagement, then the garter spring retention is improved, but the manufacturing process becomes more limited due to undercut parts during mold release
Solution Approach 1:
The annular groove is segmented into multiple sections: a first section with a larger radius of curvature for garter spring support, and a second section with a smaller radius of curvature to avoid undercut parts. This segmentation allows the groove to simultaneously provide adequate spring retention while maintaining manufacturability during mold release.
Solution Approach 2:
Different sections of the annular groove are given different local geometric properties. The first section has a larger radius of curvature specifically where the garter spring contacts the groove, while the second section has a smaller radius of curvature to facilitate mold release. This local differentiation resolves the contradiction between spring retention and manufacturing ease.
2Reliability
If fluororubber material is used for the sealing device body, then the chemical resistance and durability are improved, but the material is prone to cracking and disengagement of the garter spring during assembly
Solution Approach 1:
The radius of curvature parameter of the annular groove is optimized to be larger in the first section, which reduces stress concentration on the fluororubber material during assembly. This parameter change accommodates the lower crack resistance of fluororubber while maintaining the chemical resistance benefits of the material.
3Reliability
If the annular groove is designed with a large supported region for the garter spring, then the garter spring disengagement is prevented, but the undercut part increases causing seal lip damage during mold release
Solution Approach 1:
The annular groove is divided into functional sections: the first section provides adequate spring support, while the second section is designed with smaller radius to prevent undercut parts that would damage the seal lip during mold release. This segmentation resolves the contradiction between spring retention and prevention of seal lip damage.
Data Source
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AI summary
Provided is a sealing device that can suppress the disengagement of a garter spring from an annular groove. The sealing device includes a suppression part configured to suppress protrusion of a garter spring 300 out of an annular groove 221 in a case where the garter spring 300 is deformed when the sealing device 10 is attached to a shaft 20. The suppression part has a plurality of protrusion parts 222 provided at intervals in a circumferential direction in an outer peripheral surface of a seal lip 220 on a lip leading end side, the protrusion parts protruding toward a root side of the seal lip 220. The suppression part also has a support surface supporting the garter spring 300 along an outer peripheral surface thereof, the support surface being provided in a surface of the protrusion parts 222 on the root side when viewed in a cross section obtained by cutting the seal lip 220 along a plane that includes a central axis of the shaft 20.