Spherical Flared Heat Transfer Pipe for Fracture-Free Brazing

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Solution Overview

Problem

The flared portions of heat transfer pipes in existing heat exchangers are prone to fracture during formation due to high percentage of pipe expansion, and brazing material tends to drip onto the pipes.

Innovation Solution

The heat transfer pipes feature a flared portion with a spherical zone shape, where the inner diameter at the distal end is larger than at the proximal end, allowing for a broadened gap to receive brazing material and reducing the likelihood of fracture during formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the flared portion is formed by expanding the end part of the heat transfer pipe with a high percentage of pipe expansion, then the flared portion can accommodate ring-shaped brazing members, but the flared portion has a reduced thickness and may fracture during formation

Engineering Contradiction:

Improvecapacity to accommodate brazing membersVSAvoidthickness of flared portion

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The patent changes the geometric parameters of the flared portion by specifying a spherical zone shape with controlled inner diameters at proximal and distal ends. This parameter optimization allows the flared portion to achieve adequate capacity for brazing members while maintaining sufficient thickness to prevent fracture during formation.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If the flared portion has a large inner diameter at the distal end to accommodate brazing members, then the brazing material can be received, but the damage caused by formation is concentrated at the distal end

Engineering Contradiction:

Improvegap volume for brazing materialVSAvoiddamage concentration at distal end

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies spheroidality by defining the flared portion as a spherical zone with specific curvature characteristics. This curved geometry distributes the formation damage more evenly throughout the structure rather than concentrating it at the distal end, while still providing adequate gap volume to receive brazing material.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 spherical zone shape of the flared portion prevents damage concentration at the distal end, reduces the risk of fracture, and avoids brazing material dripping, enhancing the stability and integrity of the heat exchanger.

Implementation Method 1

A typical flared portion is formed by expanding the end part of a heat transfer pipe

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

the flared portion is coupled to the other pipe with a brazing material filling a gap between the other pipe and an inner wall of the flared portion

Methodology Applied

Scientific EffectBrazing: Brazing

Data Source

PatentUS20250271218A1Heat transfer pipe, heat exchanger, pipe expanding tool, pipe expanding device, method for connecting heat transfer pipe and pipe, and method for manufacturing heat exchanger

Publication Date: 2025.08.28 MITSUBISHI ELECTRIC CORP

AI summary

A heat transfer pipe has a flared portion having a shape of spherical zone with an inner diameter at the distal end being larger than an inner diameter at the proximal end. The flared portion is disposed with another pipe that is a target of coupling being disposed through the flared portion. The flared portion is coupled to the other pipe with a brazing material filling a gap between the other pipe and an inner wall of the flared portion.