Molten Glass Sealing for Fluid Flow Sensor Elements
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Solution Overview
Problem
The existing methods for manufacturing sensitive elements for fluid flow measurement devices in aeronautics are complex and inefficient, particularly in sealing conductive wires within channels, which can weaken the element and require multiple repetitive steps, making it difficult to achieve a high-quality, aggressive-environment-resistant coating.
Innovation Solution
A method involving a single immersion cycle in molten glass to seal and coat the conductive wires, using a pre-assembled sensitive element with a ceramic mandrel and platinum alloy wires, where the mandrel is preheated and slowly immersed in glass to fill channels without mechanical stress, followed by rapid extraction and annealing for stress relief, optimizing the glass coating and sealing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple repetitive coating and sealing steps are used, then the quality of glass coating and sealing is improved, but the manufacturing complexity and time increase significantly
Solution Approach 1:
The patent combines multiple separate operations (coating the mandrel exterior, sealing the longitudinal channels, and baking) into a single simultaneous immersion step. The glass mixture is applied once to both the exterior surface and interior channels during the same operation, eliminating the need for repeated coating and sealing cycles while maintaining quality standards.
Solution Approach 2:
The mandrel is preheated to a specific temperature range (800°C to 1200°C) before the glass mixture is applied. This preliminary heating action prepares the mandrel surface and channels to optimally receive and bond the glass coating in a single step, ensuring proper sealing and coating quality without requiring multiple subsequent heating cycles.
2Reliability
If ceramic slip is used to seal channels, then sealing is achieved, but the sensitive element is weakened and channels cannot be effectively filled after baking
Solution Approach 1:
The patent changes the physical state and application method of the sealing material from ceramic slip (room temperature slurry) to高温 molten glass (applied at 800°C to 1200°C). This parameter change allows the glass to be applied in a single step that simultaneously seals channels and coats the exterior, creating stronger bonds without the weakness issues associated with ceramic slip that must be baked and cannot be effectively refilled.
3Manufacturing precision
If multiple coating operations are performed to achieve desired glass thickness, then coating quality is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent merges multiple coating operations into a single immersion step where the glass mixture is applied simultaneously to the entire mandrel exterior and interior channels. This single operation achieves the desired glass thickness uniformity without requiring repeated coating and baking cycles, significantly improving manufacturing efficiency while maintaining precise thickness control.
Solution Approach 2:
The glass material is applied in a molten or semi-molten state at high temperature, allowing it to flow and distribute uniformly across the mandrel surface and into channels in a single step. The subsequent cooling and solidification phase transition ensures uniform thickness without requiring multiple application cycles, achieving both precision and productivity.
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
This approach simplifies the manufacturing process, enhances the mechanical and dielectric properties of the sensitive element, and improves its resistance to thermal and vibratory stresses, while reducing manufacturing time and costs, resulting in a high-performance device capable of withstanding aggressive environments.
Implementation Method 1
positioning said pre-assembled sensitive element close to the molten glass so that it reaches a temperature close to said glass in fusion
Implementation Method 2
the sealing of the connection wires by raising the glass in the longitudinal channels (sufficient passage and/or capillarity effect of the liquid glass)
Implementation Method 3
the outer coating by surface tension of the liquid glass on the mandrel
Implementation Method 4
The unique immersion cycle includes a step of slowly extracting the mandrel from the molten glass followed by a step of rapidly extracting the mandrel from the hot zone of the furnace
Implementation Method 5
a step of stabilizing the electrical behavior of the sensitive element assembled by stress relief during annealing of the glass at moderate and controlled temperature
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method of manufacturing an element sensitive to at least one physical parameter of a flow of fluid, comprising a step consisting in a single cycle of immersing, in molten glass, a core of a preassembled sensitive element, said core comprising at least two longitudinal channels along which there pass longitudinally at least two conducting connecting wires which are connected to an at least two-wire winding, said winding being suited to forming a resistive or inductive circuit for detecting said physical parameter, said immersion allowing the connecting wires to be sealed into the channels, allowing said channels to be filled and allowing the outside of the core to be coated in a single immersion, the core, at the end of said single immersion cycle, being sealed and coated in such a way as to obtain an assembled sensitive element. Advantageously, the winding may be "corkscrew" wound inside the longitudinal channels, immersion allowing the connecting wires to be held on the winding and controlling the space between the turns of the winding.