Resin Thermal Flow Meter with Bonded Sensor Substrate
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Solution Overview
Problem
Thermal flow meters with glass flow passages have poor corrosion resistance to alkaline liquids and are prone to thermal deformation, which affects measurement accuracy.
Innovation Solution
A thermal flow meter design featuring a resin measurement tube with a temperature detecting substrate and a reinforcing plate, bonded with adhesive, where the temperature detecting substrate and reinforcing plate are arranged along the axis with the internal flow passage interposed between them, to manage thermal stresses and enhance corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a glass flow passage is used, then thermal deformation resistance is improved, but corrosion resistance to alkaline liquids deteriorates
Solution Approach 1:
The invention uses a composite structure combining glass substrate (for thermal stability) with resin coating layers (for corrosion resistance). The glass substrate provides dimensional stability during heating, while the resin layers protect against alkaline liquid corrosion, resolving the contradiction between thermal deformation resistance and corrosion resistance.
2Object-affected harmful factors
If a resin measurement tube is used, then corrosion resistance to alkaline liquids is improved, but thermal deformation resistance deteriorates
Solution Approach 1:
The measurement tube uses a composite structure with resin as the base material (providing corrosion resistance) and glass substrate with thermal conduction layers (providing thermal stability). This composite approach allows the resin to contact alkaline liquids while the glass-resin interface manages thermal stresses, preventing deformation.
Solution Approach 2:
The invention introduces thermal conduction layers with specific thermal expansion coefficients between the resin and glass substrate. By carefully selecting materials with matched thermal expansion parameters, the composite structure accommodates thermal stresses during heating without causing resin deformation or delamination.
3Extent of automation
If temperature detecting substrate is bonded to measurement tube, then temperature detection function is improved, but measurement accuracy deteriorates due to thermal deformation
Solution Approach 1:
The invention introduces thermal conduction layers as intermediary elements between the temperature detecting substrate and the measurement tube. These intermediate layers act as stress buffers that decouple the thermal expansion differences between materials, preventing distortion of the temperature detecting substrate while maintaining effective thermal contact for accurate measurement.
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 maintains measurement accuracy during heating and improves corrosion resistance to alkaline liquids by evenly distributing thermal stresses and reducing adhesive usage.
Implementation Method 1
a heating resistance element and a temperature detecting resistance element configured to detect a temperature of the liquid heated by the heating resistance element
Implementation Method 2
a temperature detecting resistance element configured to detect a temperature of the liquid heated by the heating resistance element
Implementation Method 3
the detection surface of the temperature detecting substrate is bonded with an adhesive to the measurement tube along the axis, and the reinforcing plate is bonded with the adhesive to the measurement tube
Data Source
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AI summary
Provided is a thermal flow meter including a measurement tube 11 made of resin having an inlet 11a and an outlet 11b, and an internal flow passage 10c extending along an axis X, a sensor substrate 12 having a heating resistance wire and temperature detecting resistance wires formed on a detection surface 12d along the axis X, and a reinforcing plate 13. The sensor substrate 12 is bonded to the measurement tube 11 along the axis X with an adhesive, and the reinforcing plate 13 is bonded to the measurement tube 11 along the axis X with the adhesive with the internal flow passage 10c interposed between the sensor substrate 12 and the reinforcing plate 13.