Flat Ribbon Heating Element for High Current and Thermal Fatigue
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Solution Overview
Problem
Developing an electrical heating element that can handle high current loads while maintaining a small cross section and withstanding thermal cycle loading over a long period, ensuring safe and reliable processing and connection between heated and unheated zones.
Innovation Solution
A coiled resistive wire with flat ribbon geometry, where the flat sides run parallel to the coil axis, providing a significant cross section for high current loads and elastic reaction to thermal cycles, combined with connector assemblies that ensure surface-area contact with optimized geometry and materials for low transfer resistance and reduced heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a small resistor and large wire cross section are used to handle high current loads at low voltage, then the current handling capability is improved, but the device cross section increases and space availability worsens
Solution Approach 1:
The patent transitions from conventional round wire geometry to flat ribbon geometry, changing the dimensional characteristics of the resistive element. This dimensional change allows the same cross-sectional area to be arranged in a coil configuration that fits within a smaller cylindrical envelope, effectively resolving the contradiction between current handling capability and device cross section.
Solution Approach 2:
The patent modifies the geometric parameters of the resistive element by using flat ribbon geometry with specific width-to-thickness ratios. This parameter change enables the coil to achieve the necessary electrical properties for high current handling while maintaining a compact outer diameter, thus improving power capability without proportionally increasing the device cross section.
2Area of stationary object
If a small cross section is used to reduce device size, then the device diameter is reduced, but the ability to withstand thermal cycle loading and material fatigue worsens
Solution Approach 1:
The flat ribbon geometry acts as a flexible element that can accommodate thermal expansion and contraction during cycling. The ribbon's geometry allows it to flex and deform elastically during thermal cycles, reducing stress concentration and preventing fatigue failure, thus improving reliability while maintaining a small device diameter.
Solution Approach 2:
The patent introduces dynamic flexibility into the resistive element through the flat ribbon geometry, allowing it to adapt its shape during thermal cycles. This dynamic capability enables the element to withstand repeated heating and cooling cycles without catastrophic failure, maintaining reliability in a compact form factor.
3Ease of manufacture
If conventional wire geometry is used, then manufacturing is simpler, but the elastic response to thermal cycles and reduction of material fatigue is insufficient
Solution Approach 1:
The patent changes the geometric parameters from round wire to flat ribbon with controlled width and thickness ratios. This parameter change provides the necessary flexibility to withstand thermal cycling while maintaining manufacturability through established ribbon coiling processes, thus improving strength without sacrificing ease of manufacture.
4Reliability
If surface-area contact is implemented in connector assemblies, then connection reliability and current handling are improved, but manufacturing complexity increases
Solution Approach 1:
The flat ribbon geometry provides a naturally extended surface area that can be contacted by the connector assembly. This dimensional change from point contact to surface contact improves connection reliability and current handling capability while the connector design remains relatively simple, thus improving reliability without excessive increase in device complexity.
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 coiled resistive wire with flat ribbon geometry enables a more elastic response to thermal cycles, reducing material fatigue and fracture risk, while the surface-area contact configuration ensures reliable manufacturing and efficient high current handling without increasing the device's diameter.
Implementation Method 1
electrical heating element that can handle high current loads... coiled resistive wire... resistive wire with flat ribbon geometry
Data Source
AI summary
An electrical heating element for an electrical heating device is provided, wherein the electrical heating element is made from a coiled resistive wire with flat ribbon geometry and one or two connector assemblies, wherein the resistive wire with flat ribbon geometry is coiled into coils with an inner diameter, an outer diameter, and a distance between adjacent coils such that the flat side of the resistive wire with flat ribbon geometry runs parallel to the coil axis, and wherein the connector assemblies have at least one connection element that is in surface-area contact with a section of the resistive wire with flat ribbon geometry. In addition, an electrical heating device with such an electrical heating element and a method for manufacturing such an electrical heating device are also provided.