Hooked Coupling Fitting Structure for Negative-Pressure Sealing

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Solution Overview

Problem

Existing coupling fittings fail to effectively seal channels when subjected to negative pressure, leading to potential air suction and reduced performance, and lack versatility due to specialized structures for specific applications.

Innovation Solution

A coupling fitting design featuring a cylindrical body with protrusions and hooks, along with a seal material, allows for engagement and sealing even under negative pressure, enabling versatile coupling with standard fittings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coupling fitting with seal material pressed against each other under positive pressure is used, then fluid leakage is suppressed, but the seal material cannot function sufficiently under negative pressure causing air suction

Engineering Contradiction:
Improvesealing performanceVSAvoidapplicability to negative pressure
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent inverts the sealing mechanism by having the seal material extend into the coupling fitting's internal cavity rather than relying on external pressure to press seal materials together. This allows the seal to function effectively under both positive and negative pressure conditions, resolving the contradiction between positive pressure sealing and negative pressure adaptability

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If a special structure with enlarged inner diameter and O-ring is provided for both fittings to enable negative pressure sealing, then the seal material can function under negative pressure, but the versatility of the coupling fittings deteriorates

Engineering Contradiction:
Improvesealing performance under negative pressureVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the special sealing structure from both fittings and concentrates it in only one fitting. The second coupling fitting maintains a simple cylindrical shape without enlarged inner diameter or additional O-rings, while the first coupling fitting contains the extended seal material that enables negative pressure sealing. This resolves the contradiction between achieving negative pressure sealing and maintaining simplicity/versatility

Inventive Principle:
Principle #2Taking out (Extraction)

3Strength

If hooks are added to protrusions for engagement, then coupling strength is improved, but the structure becomes more complex

Engineering Contradiction:
Improvecoupling strengthVSAvoidcoupling part structure
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges the engagement function into the existing protrusion structure by adding hooks to the protrusions. This integrates the coupling and engagement functions into a single structural element rather than requiring separate components, thereby improving coupling strength while minimizing the increase in overall structural complexity

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4227567B1Coupling metal fitting and coupling structure
Publication Date: 2026.04.01 SAKURA GOMME KK
  • EP4227567B1 patent drawingFigure 1
  • EP4227567B1 patent drawingFigure 2
  • EP4227567B1 patent drawingFigure 3

AI summary

A coupling fitting comprises a cylindrical first body having a first end portion, a first coupling part having a plurality of first protrusions arranged around the first end portion and having hooks formed thereon, and a first seal material provided on an outer circumference of the first end portion. A gap is formed between the outer circumference and the plurality of first protrusions. When the coupling fitting is coupled with the target fitting, a part of the target fitting is inserted into the gap, the hooks of the plurality of first protrusions engage the target fitting, and the first seal material contacts an inner circumference of the target fitting.