Flow Sensor Laser Welding Gate Thickness Optimization
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Solution Overview
Problem
Conventional laser welding methods for flow sensors using PBT resin face challenges such as low transmittance near the gate, leading to unstable welding and difficulty in appearance inspection, along with productivity issues due to pyrolytic component generation and cleaning requirements.
Innovation Solution
The flow sensor design incorporates thinner cover portions near the gate to improve transmittance and stability, with concave parts and adjusted thickness to enhance laser welding precision and inspection capabilities, while maintaining high reliability and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laser welding method is used on PBT resin cover, then welding can be performed, but transmittance near gate is low causing unstable welding and complicated control
Solution Approach 1:
The patent applies local quality by creating a concave portion specifically at the gate area where laser transmittance is low. This localized structural modification allows the thickness to be reduced only in the problematic gate region, improving laser penetration and welding stability there, while maintaining normal thickness in other areas where transmittance is already sufficient.
Solution Approach 2:
The patent changes the physical parameter of cover thickness in the gate area by forming a concave portion. This parameter change (reducing thickness) directly addresses the low transmittance issue at the gate, allowing consistent laser welding without needing to adjust laser power or speed, thereby simplifying control.
2Difficulty of detecting and measuring
If conventional laser welding method is used on PBT resin cover, then welding can be performed, but appearance inspection cannot be performed using images due to low transmittance near gate
Solution Approach 1:
The concave portion is localized to the gate area, creating a transparent window specifically where inspection is needed. This allows optical inspection systems to clearly view the welding quality at the gate region without being obstructed by the normally opaque PBT resin, while maintaining structural integrity elsewhere.
3Productivity
If laser welding is performed on PBT resin cover with conventional method, then housing and cover can be connected, but pyrolytic components are generated requiring cleaning and reducing productivity
Solution Approach 1:
By changing the thickness parameter in the gate area through concave formation, the patent enables laser welding to pass through the cover material more efficiently. This reduces the energy required for welding and minimizes excessive heat input that causes pyrolysis, thereby reducing harmful gas generation and eliminating the need for frequent cleaning operations.
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 results in a high-quality, reliable flow sensor with improved productivity and cost-effectiveness by stabilizing the welding process and enabling effective appearance inspection, reducing transmittance variations, and minimizing pyrolytic component generation.
Implementation Method 1
at least a thickness of one portion that transmits laser light near a gate part of the cover is thinner than thicknesses of the other portions that transmit the laser light
Implementation Method 2
a laser welding method is used
Implementation Method 3
making welding effectively
Data Source
AI summary
Provided is a welding structure which enables external visual checks and has improved stability of bonding properties at a laser weld between a cover and a housing of this flow sensor. This flow sensor is provided with a housing, a cover, a circuit chamber sealed between these and housing electronic components or wiring, and a subpassage through which the fluid flows that is to be sensed, and is characterized in that at least the part near the gate section of the cover that transmits the laser is thinner than the other parts that transmit the laser.