Heat Shrink Assembly Heat Exchangers Thermal Interference Fit

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Solution Overview

Problem

Conventional heat exchanger assemblies for aerospace applications are costly and prone to cross-leaking issues due to manufacturing defects, requiring meticulous assembly checks to ensure fluid integrity.

Innovation Solution

The assembly employs an interference fit between cylindrical heat exchanger members with helical fluid passages, utilizing thermal resizing through heating or cooling to achieve a tight seal, and additional nested pairs within an outer shell, with optional sealing methods like weld joints, braze joints, and O-rings to prevent leaks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional assembly techniques are used, then manufacturing precision can be maintained, but assembly cost increases and cross-leak risk remains

Engineering Contradiction:

Improvefluid integrityVSAvoidassembly cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by utilizing thermal expansion and contraction properties of materials. The outer member is heated to expand its inner circumference, allowing easy insertion of the inner member, then cooled to contract and create an interference fit that seals fluid passages. This temperature parameter change enables reliable sealing without complex assembly procedures or high costs.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex mechanical sealing systems with a thermal-mechanical interference fit system. Instead of using multiple seals, gaskets, or precision-machined mating surfaces, the invention uses controlled thermal expansion and contraction to create a self-sealing interference fit between the outer and inner members, simplifying the mechanical system while maintaining fluid integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If interference fit is used to seal fluid passages, then cross-leak risk is reduced, but assembly complexity increases due to thermal resizing requirements

Engineering Contradiction:

Improveseal integrityVSAvoidassembly process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses parameter changes (temperature) to simplify what would otherwise be a complex assembly process. By heating the outer member and cooling the inner member, the interference fit assembly becomes straightforward - the thermal parameters enable easy insertion followed by automatic sealing upon thermal equalization, reducing overall assembly complexity despite the thermal resizing step.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If meticulous assembly checks are performed, then cross-leak detection improves, but assembly time increases

Engineering Contradiction:

Improvedefect detectionVSAvoidassembly speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies beforehand cushioning by designing the interference fit system to inherently prevent manufacturing defects before they can cause cross-leaks. The thermal resizing process and resulting interference fit create a self-sealing mechanism that compensates for minor manufacturing variations, eliminating the need for meticulous post-assembly checks and defect detection procedures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 approach reduces the risk of cross-leaks, lowers assembly costs, and facilitates efficient quality control by ensuring a secure fluid passage connection, enhancing the reliability and efficiency of heat exchanger systems.

Implementation Method 1

The second member is engaged to the first member with an interference fit. The fluid passages of first member can be sealed against the second member by the interference fit.

Methodology Applied

Scientific EffectInterference fit:

Implementation Method 2

thermally resizing at least one of a first heat exchanger member and a second heat exchanger member... thermally resizing can include heating the first heat exchanger member

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

thermally resizing can include cooling the second heat exchanger member

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 4

The fluid passages of at least one of the first and second members can be sealed by the interference fit, and at least partially by a braze joint

Methodology Applied

Scientific EffectBrazing: Brazing

Data Source

PatentEP4184107A1Heat shrink assembly heat exchangers

Publication Date: 2023.05.24 COLLINS ENGINE NOZZLES INC

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AI summary

A heat exchanger assembly includes a first member (102) defining fluid passages therein for a first heat exchanger fluid. A second member (106) defines fluid passages therein for a second heat exchanger fluid. The second member (106) is engaged to the second member (106) with an interference fit. A method of assembling a heat exchanger includes thermally resizing at least one of a first heat exchanger member and a second heat exchanger member and assembling the second heat exchanger member to the first heat exchanger member. The method includes thermally equalizing the first and second heat exchanger members to engage the second heat exchanger member to the first heat exchanger member with an interference fit.