Thin Adhesive Layer for Heat Exchanger Element Bonding

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Solution Overview

Problem

Current methods for producing heat exchanger elements are time-consuming and expensive due to the need for soldering or high-layer adhesive application, which restricts material compatibility and increases costs, while also reducing service life with thermal changes.

Innovation Solution

A method involving the application of a thin adhesive layer (10 µm to 500 µm thick) between heat exchanger elements, which are then joined at a temperature of 100°C to 200°C, ensuring a secure and stable bond with reduced material usage and faster curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If soldering is used to connect heat exchanger elements, then the connection is strong and sealed, but the process is time-consuming and expensive, requiring temperatures close to the melting point of the base material and multiple steps

Engineering Contradiction:
Improveconnection strengthVSAvoidmanufacturing time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The patent changes the temperature parameter from soldering temperatures (close to base material melting point, around 650°C) to adhesive curing temperatures (100°C to 200°C). This parameter change enables a completely different joining method that is faster and less energy-intensive while achieving comparable connection strength through chemical bonding rather than metallurgical bonding.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/thermal soldering process with a chemical adhesive bonding process. Instead of melting and flowing solder material to create joints, the invention uses adhesive layers that cure through chemical reactions, eliminating the need for high-temperature furnaces and complex soldering procedures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If soldering is used to connect heat exchanger elements, then the connection is sealed, but the process is expensive and complex, requiring fluxes, degreasing, and multiple quality checks

Engineering Contradiction:
Improvesealing qualityVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex intermediate steps of the soldering process (degreasing, flux application, high-temperature heating, quality checks) by replacing them with a single adhesive application and curing step. The adhesive itself provides both sealing and bonding functions, removing the need for separate flux and sealing materials.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The adhesive layer performs multiple functions simultaneously: it bonds the heat exchanger elements together, seals the joints to prevent leakage, and compensates for thermal expansion differences. This multi-functionality replaces the separate roles previously filled by solder, flux, and thermal expansion compensation mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If different materials are connected through soldering, then the connection can be made, but the thermal expansion differences reduce service life with frequent thermal changes

Engineering Contradiction:
Improvematerial compatibilityVSAvoidservice life
Core Design Contradiction:
Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the bonding mechanism from rigid metallurgical bonding to flexible chemical bonding. The adhesive layer can accommodate thermal expansion and contraction of different materials without creating stress concentrations that would lead to failure, thereby extending service life while maintaining material compatibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material structures where heat exchanger elements made of different materials (e.g., aluminum and copper) are joined by an adhesive layer. This creates a composite joint that leverages the advantages of each material while the adhesive compensates for their incompatibilities, particularly thermal expansion differences.

Inventive Principle:
Principle #40Composite materials

4Adaptability or versatility

If adhesive bonding is used with layer thicknesses greater than 1mm, then the flexibility for thermal expansion compensation is improved, but the curing time increases and costs increase due to large amounts of adhesive

Engineering Contradiction:
Improvethermal expansion compensationVSAvoidcuring time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent optimizes the adhesive layer thickness parameter to the range of 10 µm to 500 µm. This parameter optimization achieves the right balance: the layer is thin enough to cure quickly and use minimal adhesive, yet thick enough to provide sufficient flexibility for thermal expansion compensation and adequate bonding strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies adhesive in a controlled, moderate amount (10-500 µm thickness) rather than using excessive thickness (>1mm). This partial action approach provides just enough adhesive to achieve the required bonding and thermal compensation without the diminishing returns of excessive adhesive that would increase curing time and cost.

Inventive Principle:
Principle #16Partial or excessive action

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 results in cost-effective, high-quality heat exchanger production with improved durability and media resistance, while accommodating different thermal expansions without the limitations of traditional soldering or high-adhesive methods.

Implementation Method 1

a first heat exchanger element and with a second heat exchanger element, the two heat exchanger elements being connectable to one another at respective contact surfaces

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

the heat exchanger elements are joined at a temperature of approx. 100° C. to 200° C. or the heat exchanger elements to be connected are heated to a temperature of 100° C. to 200° C. for a predeterminable period of time after joining

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP2976220B1Method for producing connected heat exchanger elements
Publication Date: 2019.05.08 MAHLE INT GMBH
  • EP2976220B1 patent drawingFigure 1~2
  • EP2976220B1 patent drawingFigure 3

AI summary

The invention relates to a method for producing connected heat exchanger elements (1, 2, 4, 5) having a first heat exchanger element (1, 4) and a second heat exchanger element (2, 5), wherein the two heat exchanger elements can be connected to one another at respective contact surfaces, and an areal adhesive layer (3, 6) approximately 10 µm to 500 µm thick is applied to at least one of the heat exchanger elements (1, 2, 4, 5) and the two heat exchanger elements (1, 2, 4, 5) to be connected are joined to one another at the contact surfaces with interposition of the adhesive layer (3). The invention also relates to a connected heat exchange element and a heat exchanger related thereto.