Pipe Joint Bead Sealing Design for Multi-Layer Leakage Prevention

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Solution Overview

Problem

Conventional pipe joints used for connecting coolant pipes in air conditioners suffer from deteriorated sealing performance due to concavity and convexity issues between the flared portion and the pipe joint body, leading to coolant leakage.

Innovation Solution

A pipe joint design featuring a pipe joint body with a male thread and a nut member with a female thread, where a bead on the connecting pipe is held between the pipe joint body's first and second joining faces, forming three sealed portions, ensuring excellent sealing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a flared portion is formed on the coolant pipe and held between the pipe joint body and flare nut, then the pipe joint can be assembled, but the sealing performance deteriorates due to concavity and convexity like scratches in the sealed portion

Engineering Contradiction:
Improveease of assemblyVSAvoidsealing performance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The sealing function is segmented into multiple independent sealed portions (first sealed portion between bead and pipe joint body, second sealed portion between bead and nut member, third sealed portion between end face and nut member inner circumference). This segmentation ensures that if one sealed portion has defects like scratches, the other sealed portions can still maintain sealing performance, thereby resolving the contradiction between ease of assembly and sealing reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bead structure is designed as a preliminary cushioning element that distributes contact pressure and compensates for surface irregularities before the final tightening. The bead's expanded form factor absorbs minor dimensional variations and surface defects, preventing them from compromising the sealed portions, thus maintaining high sealing performance while keeping the assembly process simple.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Device complexity

If conventional flare connection is used, then assembly is simple, but additional components like front and back ferules are needed, increasing production costs and work precision variability

Engineering Contradiction:
Improvenumber of componentsVSAvoidwork precision variability
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The bead structure integrates multiple functions into a single component: it serves as both the connection element (replacing front and back ferules) and the sealing element (forming multiple sealed portions). This merging reduces the total number of components needed while also reducing the accumulation of manufacturing precision errors that would occur with multiple separate components, thereby resolving the contradiction between device complexity and manufacturing precision.

Inventive Principle:
Principle #5Merging (Combining)

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

The design provides a reliable sealing performance by creating multiple sealed portions, preventing coolant leakage even with scratches, and eliminates the need for additional components like front and back ferules, reducing production costs and variability in work precision.

Implementation Method 1

the bead is held between the first joining face and the second joining face

Methodology Applied
Scientific EffectMechanical Fastening: Mechanical Fastener

Implementation Method 2

the joined portion between the bead and the first joining face forms a first sealed portion, while the joined portion between the bead and the second joining face forms a second sealed portion

Methodology Applied
Scientific EffectSealing through compression: Compression

Data Source

PatentEP2835568B1Pipe joint connected with a pipe, and connection method therefor
Publication Date: 2019.07.24 MITSUBISHI ELECTRIC CORP
  • EP2835568B1 patent drawingFigure 1
  • EP2835568B1 patent drawingFigure 2
  • EP2835568B1 patent drawingFigure 3

AI summary

A pipe joint (10) is connected with a connecting pipe (101), and includes a pipe joint body (20) and a nut member (30). When the connecting pipe (101) formed with a bead (101a) expanded in the radial direction is connected with this pipe joint (10), a male thread (25) of the pipe joint body (20) is engaged with a female thread (33) of the nut member (30) to hold the bead (101a) between a tapered face (22) and a tapered face (34). In addition, the joined portion between the bead (101a) and the tapered face (22) forms a first sealed portion, and a joined portion between the bead (101a) and the tapered face (34) forms a second sealed portion. Still further, a tapered face (24) of the pipe joint body (20) is joined with the tapered face (34) of the nut member (30) to form a third sealed portion.