Thermally Broken Fenestration Frames for Bi-Metallic Expansion
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Solution Overview
Problem
Aluminum fenestration systems experience the bi-metallic effect, where exterior and interior extrusions expand differently due to temperature differences, causing interference with frames and difficulty in opening/closing doors or windows.
Innovation Solution
Incorporating a central extrusion with thermal breaks and insulators between exterior and interior extrusions, using retainer clips and thermal barriers to mitigate thermal conduction and maintain consistent lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum extrusions are used for structural members, then structural longevity and corrosion resistance are improved, but thermal conduction increases causing the bi-metallic effect
Solution Approach 1:
A central extrusion made of low-conductance material is introduced as an intermediary between the exterior and interior aluminum extrusions. This central component acts as a thermal barrier, blocking heat transfer while maintaining the structural continuity and longevity provided by aluminum extrusions on both ends.
Solution Approach 2:
The frame member is constructed as a composite assembly combining aluminum extrusions with a low-conductance central extrusion. This composite structure leverages the strength and corrosion resistance of aluminum while incorporating the thermal insulation properties of the low-conductance material to eliminate the bi-metallic effect.
2Loss of energy
If thermal breaks are added to reduce thermal conduction, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The central extrusion performs multiple functions simultaneously: it provides thermal insulation, maintains structural integrity, and connects the exterior and interior extrusions. By merging these functions into a single integrated component, the design achieves effective thermal breaking without proportionally increasing structural complexity.
3Temperature
If exterior extrusion is heated to elevated temperature, then thermal radiation from sun is utilized, but bi-metallic effect causes interference with door operation
Solution Approach 1:
The extrusion system is segmented into three distinct parts: an exterior aluminum extrusion exposed to solar heating, a central low-conductance extrusion that acts as a thermal break, and an interior aluminum extrusion maintained at room temperature. This segmentation prevents heat transfer that would cause the bi-metallic effect, ensuring the door remains operable despite exterior heating.
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
Reduces thermal conduction and minimizes the bi-metallic effect, enhancing structural integrity and ease of operation by maintaining consistent frame member lengths.
Implementation Method 1
a thermal break to couple the exterior extrusion and the central extrusion
Implementation Method 2
an insulator positioned between the exterior extrusion and the central extrusion
Implementation Method 3
the exterior extrusion can be heated to an elevated temperature, such as 170°F, which causes the exterior extrusion to expand and bow relative to the interior extrusion
Data Source
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AI summary
A fenestration is disclosed comprising a plurality of frame members. At least one of the frame members comprises an exterior extrusion, an interior extrusion, a central extrusion intermediate the interior extrusion and the exterior extrusion, and a thermal break to couple the exterior extrusion and the central extrusion.