Vacuum Glazing Evacuation Seal Geometry for Lower Shear Stress
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Solution Overview
Problem
Vacuum insulated glazing (VIG) 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 seal and glass sheets, especially under wind and temperature changes.
Innovation Solution
A vacuum insulated glazing unit design featuring a sealing material with a contact angle below 45 degrees between the glass surface and the sealing material, and between the sealing material and the evacuation member, reducing the thickness of the seal and minimizing shear forces, along with a glass tube evacuation member to match thermal characteristics, thereby reducing stress and strain on the seal and glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing material is made thicker to improve sealing efficiency, then the sealing efficiency is improved, but the shear forces between the sealing material and glass sheet increase causing higher risk of fractures and cracks
Solution Approach 1:
The patent changes the contact angle parameter of the sealing material from a conventional larger angle to specifically below 45 degrees. This parameter change reduces the thickness of sealing material deposited on the glass sheet surface while maintaining effective sealing, thereby reducing shear forces and the risk of fractures and cracks during thermal contraction.
Solution Approach 2:
The patent employs a concave surface shape of the sealing material instead of a flat or convex shape. This curvature design naturally reduces the thickness of sealing material at the glass sheet interface, decreasing shear forces while maintaining sealing effectiveness. The concave shape allows the seal to accommodate thermal contraction with reduced stress concentration.
2Stability of the object's composition
If a glass tube evacuation member is used to match thermal characteristics, then the thermal expansion mismatch is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent uses a glass tube evacuation member made of the same material as the glass sheets, creating material homogeneity throughout the structure. This ensures matched thermal expansion characteristics, preventing stress concentration and potential failure during temperature changes. The homogeneous material composition stabilizes the overall structure under thermal loading.
3Duration of action of stationary object
If the contact angle is reduced below 45 degrees to reduce shear forces, then the durability is improved, but the sealing material deposition control becomes more difficult
Solution Approach 1:
The patent specifies a quantitative parameter threshold (contact angle below 45 degrees) that balances durability improvement with manufacturing feasibility. This clear parameter guideline provides manufacturers with a specific target, making the deposition control requirement more manageable while still achieving the durability benefits of reduced shear forces.
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 enhances the durability and reduces the risk of cracks and fractures, decreases the amount of sealing material needed, and lowers production costs while maintaining effective thermal insulation.
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. Upon cooling of the seal material, it will harden to non-flowing state
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 and so that a shear force is induced between the hermetic seal and the surface of the glass sheet
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~3b
AI summary
A vacuum insulated glazing unit (1) is disclosed comprising a first glass sheet (2) and a second glass sheet (2) separated by a gap (7), with one or more support structures (8) arranged in said gap (7), and a side seal (9) arranged near the periphery of said glass sheets (2) and enclosing said gap (7), wherein one of said glass sheets (2) comprises an evacuation hole (4) and an evacuation member (6), and a sealing material (3) providing a hermetic seal between the evacuation member and said glass sheet (2), and the sealing material (3) having a sealing material surface (3a) extending between a first intersection defined between a surface (2b, 5) of the glass sheet (2) and the sealing material surface (3a) and a second intersection defined between the evacuation member and the sealing material surface (3a), wherein said sealing material surface (3a) at the first intersection has a first contact angle (A1) defined between said sealing material surface (3a) and the surface (2b, 5) of the glass sheet (2), which first contact angle (A1) is below 4 degrees, such as below 40 degrees. 1