Thermoelastic Strand Bundle Pre-Strain for Uniform Converter Loading

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Solution Overview

Problem

Existing thermoelastic assemblies with a large number of strand elements suffer from manufacturing tolerances leading to uneven stress levels, affecting service life and reliability.

Innovation Solution

A method for producing thermoelastic arrangements by fixing thermoelastic strand elements with constant strain between retaining elements to form bundles with identical pre-stresses, ensuring uniform aging and degradation, and allowing for simple electrical control and reproducible movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a piezoelectric energy converter is used to harvest energy from vibrations, then electrical energy can be generated, but the converter requires a minimum acceleration threshold to generate sufficient power, causing loss of energy during low-acceleration events

Engineering Contradiction:
Improvepower generationVSAvoidenergy loss during low acceleration
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent combines a piezoelectric converter and a thermoelastic converter in a hybrid energy harvesting system. The piezoelectric converter handles high-acceleration events where it generates sufficient power above its threshold, while the thermoelastic converter simultaneously captures energy from low-acceleration events that would otherwise be lost, merging their complementary strengths to eliminate the minimum acceleration threshold requirement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The thermoelastic converter acts as an intermediary component that captures energy from vibration events too weak to activate the piezoelectric converter. By introducing this intermediate energy harvesting mechanism, the system recovers energy from the full spectrum of vibration intensities, including those below the piezoelectric threshold.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a piezoelectric converter operates below its minimum acceleration threshold, then it cannot generate sufficient electrical power, but this creates a minimum acceleration requirement that limits energy harvesting opportunities

Engineering Contradiction:
Improvepower generation reliabilityVSAvoidadaptability to different acceleration levels
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The hybrid system merges two different energy conversion mechanisms with complementary operating characteristics. The piezoelectric converter provides reliable high-power output during strong vibrations, while the thermoelastic converter provides reliable low-power output during weak vibrations, together achieving both reliability across all conditions and adaptability to varying acceleration levels.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The energy harvesting system achieves multi-functionality by incorporating two converter types that operate across different acceleration ranges. This universal design allows the system to effectively harvest energy from both high-acceleration and low-acceleration events, making it adaptable to a wide variety of vibration conditions without requiring separate systems for different scenarios.

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

3Productivity

If a hybrid energy converter combining piezoelectric and thermoelastic converters is used, then energy can be harvested from both high and low acceleration events, but the device complexity increases

Engineering Contradiction:
Improveenergy harvesting productivityVSAvoidconverter system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges two energy conversion technologies into a single integrated hybrid converter assembly. By combining the piezoelectric and thermoelastic converters in one unified structure with shared mounting and electrical connections, the system achieves enhanced energy harvesting productivity across all acceleration levels while minimizing the complexity increase that would result from separate independent systems.

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

This method enhances the reproducibility, reliability, and service life of thermoelastic converters by preventing uneven stress on individual strand elements, thereby improving the performance and longevity of actuator systems.

Implementation Method 1

a piezoelectric energy converter which converts vibrations into electrical energy

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a thermoelastic converter arrangement... wherein a first converter element and a second converter element are coupled to one another in a stacked arrangement, the first converter element and the second converter element being made of different materials having different coefficients of thermal expansion

Methodology Applied
Scientific EffectThermoelastic effect: Thermoacoustic Effect

Data Source

PatentEP4139572B1Energy converter having a thermoelastic converter arrangement and method for producing a thermoelastic converter arrangement for an energy converter
Publication Date: 2026.05.06 UNIVERSITAT DES SAARLANDES
  • EP4139572B1 patent drawingFigure 1a~1b
  • EP4139572B1 patent drawingFigure 1c
  • EP4139572B1 patent drawingFigure 2

AI summary

The invention relates to a method for producing a thermoelastic arrangement for an energy converter, wherein thermoelastic strand elements (6) with a constant elongation are fixed between at least two retaining elements (7, 7a, 7b) in order to obtain a bundle of strand elements (6) extending in the longitudinal direction and having identical pre-elongation.