Hinged Heating Element Support for Thermal Stress Relief
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Solution Overview
Problem
High-temperature heating elements in systems like MOCVD reactors face significant mechanical stress due to thermally induced cyclic expansion and contraction, leading to potential plastic deformations and short circuits, especially when using refractory metals, which are prone to strength creep and deformation at elevated temperatures.
Innovation Solution
A supporting system with a rigid, elongated supporting member and a hinged base member allows controlled thermal expansion in a single direction, reducing mechanical stress by enabling movement perpendicular to the height direction, and is designed to operate above 1600°C with refractory metals, ensuring the supporting system does not exceed the limiting creep stress of the heating element material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heating elements are fixed in place by rigid terminals, then precise positioning is maintained, but thermally induced mechanical stress causes plastic deformations and reduces lifetime
Solution Approach 1:
The patent applies the dynamics principle by replacing rigid fixed terminals with a dynamic support structure comprising a supporting member and a hinge connection. The hinge enables the supporting member to rotate, allowing the heating element to expand thermally while maintaining controlled positioning. This dynamic mechanism resolves the contradiction by permitting movement to relieve mechanical stress while preserving positioning precision through the constrained rotational degree of freedom.
2Strength
If flexible support structures with springs are used, then thermal expansion is accommodated, but the heating element may contact other parts causing short circuits
Solution Approach 1:
The patent applies the dimensionality change principle by transitioning from a horizontal spring-based flexible support to a vertical hinge-based support mechanism. The hinge rotates in a vertical plane, allowing thermal expansion to be accommodated through rotational movement in one dimension while maintaining horizontal separation from other heating elements. This dimensional shift prevents short circuits while providing the necessary flexibility for thermal expansion.
3Manufacturing precision
If pins are used to fix heating elements in a plane, then positioning is controlled, but at high temperatures pins bond to heating elements via diffusion hindering movement
Solution Approach 1:
The patent applies the intermediary principle by introducing a hinge as a mediating component between the fixed base member and the heating element. The hinge acts as an intermediary that transmits the thermal expansion force while preventing direct contact and diffusion bonding between the pin-like fixtures and the heating element. This intermediary mechanism maintains positioning control through the hinge's rotational constraint while allowing free thermal expansion without harmful metallurgical bonding.
4Temperature
If refractory metals are used for heating elements above 1600°C, then high temperature operation is achieved, but strength creep resistance decreases substantially
Solution Approach 1:
The patent applies the 'blessing in disguise' principle by converting the harmful thermal expansion and creep deformation of refractory metals at high temperatures into a beneficial controlled movement mechanism. Instead of resisting the natural thermal expansion that causes stress and deformation, the hinge-supported structure allows controlled rotational movement that accommodates expansion. This transforms the previously harmful effect into a functional feature that protects the heating element from stress-induced failure while enabling operation above 1600°C.
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 solution effectively reduces thermally induced mechanical stress and the risk of plastic deformations, maintaining precise positioning and extending the lifespan of heating elements by allowing controlled expansion, thus preventing short circuits and ensuring a homogeneous temperature profile in high-temperature applications.
Implementation Method 1
heat is generated when an electric current is applied through the electric conductive heating elements, also known as heating filaments, and due to electric resistance electric energy is dissipated into heat
Implementation Method 2
one of the main issues one has to cope with is the thermally induced cyclic expansion and contraction of the heating elements
Data Source
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AI summary
The invention relates to a supporting system for support of a heating element which comprises a supporting member and a base member. The supporting member has a main extension direction extending substantially in a height direction and a proximal and distal end whereas the proximal end is adapted to support the heating element. The base member is connected via at least one hinge to a distal portion of the supporting member which distal portion is arranged distal from the proximal end. The supporting member is pivotable relative to the base member about a rotation axis which is oriented parallel to a substantially rigid direction.