Vacuum Glazing Evacuation Seal Geometry for Lower Shear Stress
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Solution Overview
Problem
Vacuum insulated glazing units face challenges in maintaining sealing efficiency and durability due to thermal contraction-induced shear forces, which can lead to fractures and cracks in the glass sheets and sealing material, especially when exposed to wind or temperature changes.
Innovation Solution
A vacuum insulated glazing unit design featuring a sealing material with a contact angle below 45 degrees between the glass sheet and the sealing material surface, and a concave surface curvature for the sealing material, reducing the thickness of the hermetic seal and minimizing shear forces, thereby enhancing durability and reducing the risk of cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing material is applied to form a hermetic seal between the evacuation member and glass sheet, then the airtight seal is achieved, but thermal contraction of the sealing material induces shear forces that can cause fractures and cracks
Solution Approach 1:
The patent changes the contact angle parameter of the sealing material surface to be below 45 degrees (preferably below 30 degrees). This parameter change reduces the thickness of sealing material deposited on the glass sheet surface, thereby reducing the shear forces induced by thermal contraction while maintaining adequate seal thickness for hermetic sealing.
2Reliability
If a larger amount of sealing material is used to ensure adequate seal thickness, then the hermetic seal is more reliable, but the shear forces from thermal contraction increase, raising the risk of cracks
Solution Approach 1:
By controlling the contact angle parameter below 45 degrees, the patent optimizes the sealing material deposition to achieve the right balance: sufficient seal thickness for reliability while limiting the total sealing material volume to reduce thermal contraction forces.
3Strength
If the contact angle of the sealing material is increased to improve bonding, then the hermetic seal strength is enhanced, but the sealing material thickness increases, leading to greater shear forces from thermal contraction
Solution Approach 1:
The patent identifies the contact angle as a critical parameter and sets it below 45 degrees to optimize the balance between bonding strength and shear force reduction, achieving both reliable bonding and reduced thermal stress.
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 design reduces the risk of fractures and cracks in the glass sheets and sealing material, decreases the amount of sealing material used, and lowers production costs while maintaining the airtight seal and thermal insulation properties.
Implementation Method 1
The sealing material is heated to a temperature where it flows and forms the seal by bonding to the surfaces of the glass sheet and of the evacuation member
Implementation Method 2
Upon cooling of the seal material, it will harden to non-flowing state and it will contract differently from, often more than the material of the glass sheet
Data Source
AI summary
A vacuum insulated glazing unit comprising a first glass sheet and a second glass sheet separated by a gap, with one or more support structures arranged in said gap, and a side seal arranged near the periphery of said glass sheets and enclosing said gap, wherein one of said glass sheets comprises an evacuation hole and an evacuation member, and a sealing material providing a hermetic seal between the evacuation member and said glass sheet, and the sealing material having a sealing material surface extending between a first intersection defined between a surface of the glass sheet and the sealing material surface and a second intersection defined between the evacuation member and the sealing material surface, wherein said sealing material surface at the first intersection has a first contact angle defined between said sealing material surface and the surface of the glass sheet, which first contact angle is below 40 degrees.