Crystalline Resin Flow Sensor Cover for Laser Welding Inspection
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Solution Overview
Problem
Flow sensors face challenges with low productivity due to the time-consuming heat-hardening adhesives used for sealing, high costs, and design constraints, as well as difficulties in controlling adhesive amounts, and the need for high transmittance in visible light for laser welding inspection, which is hindered by resin discoloration over time.
Innovation Solution
A flow sensor with a crystalline resin cover containing a non-crystalline alloy material, achieving 35% or more transmittance for wavelengths of 450 nm to 1100 nm, and satisfying specific lightness and chroma conditions in the L*a*b color system, allowing for visual inspection of laser welding quality and recognizing abnormal temperatures and usage history through discoloring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat-hardening adhesives are used for sealing the housing and cover, then sealing reliability is improved, but productivity deteriorates due to long heat hardening time
Solution Approach 1:
The patent extracts the adhesive sealing process entirely and replaces it with laser welding technology. The housing and cover are joined directly through laser welding without any adhesive, eliminating the heat hardening time constraint while maintaining sealing integrity. This is achieved by designing protrusions on the housing that fit into corresponding recesses on the cover, creating a mechanical interlock that is then sealed through laser welding.
Solution Approach 2:
The patent replaces the chemical/thermal adhesive system with a mechanical-laser welding system. The protrusion-recess mechanical structure provides alignment and initial sealing, while laser welding provides the final seal. This substitution eliminates the need for heat-hardening adhesives and their associated long curing times, significantly improving productivity while maintaining or enhancing sealing reliability.
2Reliability
If a plurality of adhesives are used for sealing and fixing, then sealing and fixing reliability are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the sealing and fixing functions into a single integrated laser welding process. The protrusions on the housing engage with recesses on the cover to provide mechanical fixing, while the same laser welding process simultaneously creates the seal. This consolidation eliminates the need for multiple separate adhesives and application steps, reducing device complexity while maintaining reliable sealing and fixing.
Solution Approach 2:
The patent extracts and removes the entire adhesive system from the design, replacing it with a single laser welding process that performs both sealing and fixing functions. This elimination of multiple adhesives and their associated application, positioning, and curing steps significantly reduces manufacturing complexity and cost while maintaining the required reliability.
3Manufacturing precision
If adhesive protrusion control area is increased, then adhesive control is improved, but design flexibility is constrained
Solution Approach 1:
The patent replaces the adhesive application and control system with a laser welding system that uses programmed motion and focused energy delivery. The laser beam can be precisely controlled to weld along specific paths without requiring large protrusion control areas. This mechanical-to-optical substitution maintains manufacturing precision while dramatically increasing design flexibility, as the laser can accommodate complex geometries and varying joint configurations without requiring additional physical space for adhesive management.
4Productivity
If laser welding is used for joining housing and cover, then productivity and cost are improved, but transmittance requirement for inspection complicates material selection
Solution Approach 1:
The patent changes the optical parameters of the resin material by selecting a crystalline resin with specific transmittance characteristics. The resin is chosen to have high transmittance in the visible range (400-700nm) to allow visual inspection of the laser weld, while also being compatible with the laser welding process. This parameter optimization balances the competing requirements of weldability and inspectability, simplifying material selection by establishing clear transmittance criteria.
Solution Approach 2:
The patent uses a composite resin material that combines crystalline structure with specific optical properties. The crystalline resin provides the necessary mechanical strength and thermal resistance for laser welding, while its optical characteristics allow visible light transmission for inspection. This composite approach integrates multiple functional requirements into a single material, reducing material selection complexity while maintaining high productivity through laser welding.
5Reliability
If resin cover is used for laser welding, then sealing and fixing are improved, but discoloration over time reduces appearance quality
Solution Approach 1:
The patent changes the chemical composition parameters of the resin material to include antioxidants and UV stabilizers. These additives modify the resin's resistance to oxidation and photodegradation, preventing discoloration over time while maintaining the resin's suitability for laser welding and sealing functions. This parameter modification extends the service life and appearance durability of the resin cover without compromising its sealing and fixing reliability.
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 configuration enables high-quality laser welding with reduced costs, ensures reliable detection of abnormal temperatures and usage history, and maintains mechanical characteristics despite discoloration, enhancing the flow sensor's performance and durability.
Implementation Method 1
a flow rate detector to measure the flow rate and configured to measure the flow rate of the gas by allowing thermal conduction between the flow rate detector and the gas to be measured
Implementation Method 2
a method of joining the housing and the cover by using laser
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3(A)~3(B)
AI summary
The purpose of the present invention is to provide a flow sensor that makes it possible to detect temperature abnormalities that the flow sensor has been exposed to and the time history of the flow sensor in a high-temperature environment from an externally visible cover material and that uses a cover material for which the laser welding quality can be guaranteed through visual inspection when the sensor is delivered as a product and even if the sensor is used in an abnormal state. A flow sensor provided with a housing, a cover, a circuit chamber that houses a wiring portion sealed between the housing and the cover, and an auxiliary passage through which the liquid to be sensed flows, wherein: a joint portion formed on the housing and a joint portion formed on the inner surface of the cover are joined together through the laser welding; the main material of the cover is a crystalline resin; the cover includes an amorphous alloy; and the cover is made to have a natural color.