Seal Groove and Backup Ring Geometry to Prevent O-Ring Cracking
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Solution Overview
Problem
Conventional seal structures experience damage, such as cracks, in the O-ring due to high pressure application, as the O-ring is pressed against a harder backup ring, leading to deformation and potential breakage.
Innovation Solution
A seal structure design featuring a seal groove with a low-pressure side groove bottom that converges towards the second seal surface, and a backup member with an abutment surface aligned with this groove bottom, preventing gaps and deformation by allowing the backup member to rotate along the groove bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a backup ring made of harder material than the O-ring is used to support the O-ring, then the O-ring is supported and positioned, but the O-ring deforms and may crack when high pressure is applied
Solution Approach 1:
The patent changes the geometric parameters of the seal groove, specifically creating a curved bottom surface with a radius of curvature that matches the backup ring. This parameter change allows the backup ring to rotate along the curved surface rather than being forced into a gap, preventing O-ring deformation and cracking while maintaining support strength
Solution Approach 2:
The patent applies curvature to the bottom surface of the seal groove, forming an arc-shaped path that the backup ring can follow. This curved geometry enables the backup ring to rotate smoothly under pressure without creating stress concentration points that would cause O-ring damage
2Force
If the O-ring is pressed against the backup ring under high pressure, then sealing force is maintained, but the O-ring moves into the gap between the backup ring and groove bottom causing deformation
Solution Approach 1:
The curved bottom surface of the seal groove provides a continuous arc-shaped contact path for the backup ring. When sealing force is applied, the backup ring rotates along this curved surface instead of being forced into a sharp-cornered gap, preventing O-ring shape deformation while maintaining effective sealing force
3Ease of manufacture
If a conventional seal groove with sharp corners is used, then manufacturing is simple, but the backup ring creates gaps that cause O-ring deformation under pressure
Solution Approach 1:
The patent modifies the groove geometry parameters by replacing sharp corners with a curved bottom surface defined by a specific radius of curvature. This parameter change eliminates gap formation while remaining manufacturable through standard machining processes, thereby maintaining ease of manufacture while improving seal integrity
Data Source
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AI summary
A seal structure, wherein a seal groove (1G) has: a high-pressure side groove bottom (1Ga) on the high-pressure side at a certain distance from the second seal surface (2a); and a low-pressure side groove bottom (1Gb) continuing the high-pressure side groove bottom (1Ga) on the low-pressure side, wherein the low-pressure side groove bottom (1Gb) becomes closer to a second seal surface (2a) in a direction from the high-pressure side groove bottom (1Ga) toward the low-pressure side, wherein a sealing member (10) is disposed between the high-pressure side groove bottom (1Ga) and the second seal surface (2a), a backup member (20) is disposed between the low-pressure side groove bottom (1Gb) and the second seal surface (2a), and the backup member (20) has an abutment surface (20c) on a side opposite the low-pressure side groove bottom (1Gb), the abutment surface (20c) having a shape along the low-pressure side groove bottom (1Gb).