Coupling Backup Ring Retention via Segmented Female Member

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Solution Overview

Problem

In high-pressure fluid pipe couplings, the deformation of the seal ring during insertion can cause the backup ring to be dislodged from its annular groove, leading to unreliable sealing due to radial outward pressure.

Innovation Solution

The design includes a front end opening section of the female coupling member with a larger diameter than the seal ring, which engages and retains the backup ring, preventing it from being dislodged, even when the seal ring deforms and presses the backup ring outward.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the seal ring is deformed by engagement with the end opening section to effect sealing, then sealing is achieved, but the backup ring is pressed radially outward and may become dislodged from the annular groove

Engineering Contradiction:
Improvesealing reliabilityVSAvoidbackup ring position stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The male member reception hole is divided into two distinct sections: a front end opening section with a larger diameter and a rear male member reception section with a smaller diameter. This segmentation allows the backup ring to be retained in the front section while the seal ring deforms in the rear section, resolving the contradiction between achieving sealing and maintaining backup ring stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The front end opening section acts as an intermediary structure that receives and retains the backup ring during the sealing process. This intermediate section prevents the backup ring from being dislodged while allowing the seal ring to deform for sealing, thus mediating between the conflicting requirements of sealing effectiveness and backup ring stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If the backup ring is made with high rigidity to support the seal ring, then seal support is improved, but the backup ring expands radially outward when pressed and may become dislodged

Engineering Contradiction:
Improvebackup ring rigidityVSAvoidbackup ring retention during insertion
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The male member reception hole is segmented into a front end opening section and a rear male member reception section. The front section with larger diameter provides a retention space for the rigid backup ring, allowing it to be held in place without requiring the backup ring to be flexible or deformable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The front end opening section creates a geometric copy or replica of the backup ring's outer diameter, providing a matching interface that retains the backup ring. This geometric correspondence ensures the rigid backup ring is held securely without needing to deform.

Inventive Principle:
Principle #26Copying

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 ensures the backup ring remains in place, maintaining reliable sealing and preventing leakage, as the inner wall surface of the front end opening section securely holds the backup ring, allowing for smooth and effective insertion of both the seal and backup rings without deformation resistance.

Implementation Method 1

the seal ring 6 is pressed between the inner wall surface of the male member reception hole 3 and the annular groove 5 and thus elastically deformed to effect sealing

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP1870623B1Assembly of male and female members
Publication Date: 2012.02.01 NITTO KOHKI CO LTD
  • EP1870623B1 patent drawingFigure 1~2
  • EP1870623B1 patent drawingFigure 3~4
  • EP1870623B1 patent drawingFigure 5~7

AI summary

The diameter of a front end opening section (20-1) extending rearward over a predetermined length from the front end opening of the male member reception hole (20) is set to be larger than that of a male member reception section (20-2) of the male member reception hole that follows the front end opening section. The backup ring (18) is allowed to engage the inner wall surface (20-3) of the front end opening section (20-1) as the backup ring (18) is pressed radially outward from the annular groove (24) by the seal ring (16) deformed by engagement with the inner wall surface of the male member reception hole (20) when the male coupling member (12) has begun to be inserted into the male member reception hole (20), thereby preventing the backup ring (18) from coming out radially outward from the annular groove (24).