Thermoelectric Module Electrode Layout for Corner Stress Relief

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Solution Overview

Problem

Thermoelectric modules face issues with thermal stress concentration in the corners of the end face of thermoelectric elements due to uneven heat transfer, leading to potential damage and reduced durability, especially on the heat-absorption side which experiences larger temperature changes.

Innovation Solution

The thermoelectric module design includes an electrode with a first joint portion at the center and second and third joint portions at the ends, positioned away from the corners, with longer joint lengths in one direction to maximize the electrode area and distribute thermal stress, and incorporates a polyimide base film for stress relief, enhancing mechanical strength and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electrode is joined to the entire end face of the thermoelectric element to improve heat transfer, then the heat transfer effect is improved, but thermal stress concentration occurs in the four corners leading to potential destruction

Engineering Contradiction:

Improveheat transfer effectVSAvoidthermal stress concentration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The electrode is designed with non-uniform joint lengths in the second direction, where the first joint portion has a longer joint length than the second and third joint portions. This creates local quality differences in the electrode structure, allowing the center portion to provide stronger support while the end portions maintain adequate connection without excessive stress concentration at the corners.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electrode structure employs asymmetric joint lengths where the first joint portion (center) has a different joint length compared to the second and third joint portions (ends). This asymmetric design prevents symmetric stress distribution that would concentrate at all corners, thereby reducing thermal stress concentration while maintaining overall heat transfer effectiveness.

Inventive Principle:

Principle #4Asymmetry

2Object-affected harmful factors

If the electrode is joined to a small area of the end face, then thermal stress concentration is reduced, but the heat transfer effect decreases

Engineering Contradiction:

Improvethermal stress concentrationVSAvoidheat transfer effect

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The joint lengths in the second direction are optimized with specific parameter relationships: the first joint length is longer than the second and third joint lengths. This parameter change allows the electrode to cover a larger effective area for heat transfer while the asymmetric distribution prevents uniform stress concentration, achieving both goals simultaneously.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If electrodes are joined to both end faces to prevent deformation, then deformation is prevented, but thermal stress occurs in the thermoelectric element

Engineering Contradiction:

Improvedeformation preventionVSAvoidthermal stress

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The electrode structure implements local quality variations through different joint lengths at different positions. The longer first joint portion provides enhanced support at the center where stress concentration would be most severe, while the shorter second and third joint portions at the ends reduce stress at the corner regions, achieving deformation prevention with reduced thermal stress.

Inventive Principle:

Principle #3Local quality

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 design effectively prevents thermal stress concentration at the corners, increases the electrode area for improved heat transfer, and enhances the module's durability by distributing thermal stress and utilizing a deformable polyimide base film for stress relief.

Implementation Method 1

When a current is caused to flow through the thermoelectric module, one end face of the thermoelectric element is cooled while the other end face opposite to one end face is heated

Methodology Applied

Scientific EffectSeebeck effect: Seebeck Effect

Implementation Method 2

unbalanced deformation tends to occur in one end face and the other end face of the thermoelectric element in accordance with the thermal expansion coefficient thereof

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

the area of the electrode joined to the end face of the thermoelectric element becomes relatively small. This poses a problem of decreasing the effect of heat transfer between an object and the thermoelectric element

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9170036B2Thermoelectric module

Publication Date: 2015.10.27 KELK LTD

AI summary

A thermoelectric module includes a thermoelectric element and an electrode. The thermoelectric element has a rectangular end face. The electrode includes a first joint portion joined to a center portion of the end face; and a second joint portion joined to one end and a third joint portion joined to the other end. Each of the second joint portion and the third joint portion is disposed at a distance from each of four corners of the end face. A joint length in the second direction orthogonal to the first direction between the first joint portion and the end face is longer than each of a joint length in the second direction between the second joint portion and the end face, and a joint length in the second direction between the third joint portion and the end face.