Compact Thermoelastic Actuator for Phase Stable Waveguide

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Solution Overview

Problem

Existing waveguide multiplexers in space equipment face phase shifts and malfunctions due to temperature variations, which existing solutions fail to address effectively without causing mechanical stresses or occupying excessive volume.

Innovation Solution

A compact thermoelastic actuator comprising force pieces with a high coefficient of thermal expansion and a holding piece with a lower coefficient, designed to minimize volume and mechanical interference, where force pieces are linearly offset and connected to external longitudinal ribs to maintain phase stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a waveguide is made of low CTE material (titanium or invar) to maintain phase stability, then phase stability is improved, but mechanical stresses occur between the waveguide and the aluminum structure during temperature variations

Engineering Contradiction:
Improvephase stabilityVSAvoidmechanical stresses
Core Design Contradiction:
Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The patent changes the material parameter (CTE) of the waveguide from low CTE (invar/titanium) to high CTE (aluminum) to match the surrounding structure, eliminating mechanical stresses. Phase stability is then achieved not by material selection but by introducing a compensation mechanism that actively counteracts thermal expansion effects through geometric deformation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes thermal expansion of the aluminum waveguide as a compensating mechanism. The waveguide's high CTE is intentionally exploited to create controlled dimensional changes that, when combined with specific geometric features (curved sides, deformation zones), produce phase compensation effects that counteract the harmful thermal phase shifts.

Inventive Principle:
Principle #37Thermal expansion

2Stability of the object's composition

If spacers and holding structures are used to compensate thermal expansion, then phase stability is improved, but the device becomes bulky and interferes with channel positioning

Engineering Contradiction:
Improvephase stabilityVSAvoiddevice complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the external holding structure and spacers from the compensation mechanism. Instead of adding separate compensation components, the phase stability function is integrated directly into the waveguide structure itself through geometric features (curved sides, deformation zones) that provide compensation without requiring external support elements.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the phase compensation function with the waveguide structure itself. The waveguide's geometric features (curved sides, deformation zones) are designed to provide thermal compensation as an inherent property of the structure, eliminating the need for separate compensation mechanisms and reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Stability of the object's composition

If the waveguide structure is laterally ribbed with plates to restrict expansion, then phase stability is improved, but the positioning latitude of channels and mechanical interfaces is reduced

Engineering Contradiction:
Improvephase stabilityVSAvoidpositioning latitude
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent applies local geometric modifications (curved sides, deformation zones) at specific locations where thermal expansion occurs, rather than applying restrictive plates along the entire waveguide. This localized approach provides phase compensation while leaving other regions free for channel positioning and mechanical interfacing, maintaining adaptability.

Inventive Principle:
Principle #3Local quality

4Stability of the object's composition

If lever mechanisms are used to compensate dimensional variations, then phase stability is improved, but the assembly becomes complex and bulky

Engineering Contradiction:
Improvephase stabilityVSAvoiddevice complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical lever mechanisms with a simplified geometric compensation approach. Instead of using rotating levers and pivots, the waveguide's curved sides and deformation zones create passive geometric compensation that achieves phase stability through the structure's own thermal deformation, eliminating the need for active mechanical compensation systems.

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

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 actuator effectively compensates for thermal expansion, maintaining phase stability while minimizing mechanical stresses and volume occupation, suitable for compact configurations and vertical multiplexing structures.

Implementation Method 1

force pieces with a high coefficient of thermal expansion

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

holding piece with a lower coefficient of thermal expansion

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2348571B1Compact waveguide actuator, phase stable waveguide and multiplexer using this actuator.
Publication Date: 2014.06.25 THALES SA
  • EP2348571B1 patent drawingFigure 1~2
  • EP2348571B1 patent drawingFigure 3a~3b
  • EP2348571B1 patent drawingFigure 4

AI summary

The compact thermoelastic actuator (15) comprises at least two identical force pieces (10a, 10b, 10c, 10d) and a retaining piece (11), the retaining piece having a coefficient of thermal expansion lower than the coefficient of thermal expansion of the force pieces. The force pieces (10a, 10b, 10c, 10d) are mounted end-to-end side by side parallel to a longitudinal axis Y and are linearly offset from each other along the longitudinal axis Y. The retaining piece (11) has two ends respectively connected to external ends of each force piece, and internal ends of each force piece are positioned under a median zone (14) of the retaining piece (11). Application to waveguides of multiplexers integrated into space equipment for satellites.