Insulated Sensing Tube Layout for Low-Drift Mass Flow Control
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Solution Overview
Problem
Existing fluid measurement sensors suffer from zero drift due to asymmetric heat distribution caused by structural issues and heat dissipation at joints, leading to poor precision and repeatability in gas mass flow controllers.
Innovation Solution
A fluid measurement sensor design featuring a sensing tube wrapped with thermal insulation, symmetrically arranged within a mounting groove, and secured by a bracket system to prevent heat dissipation at joints, ensuring uniform heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two housings are combined into a cavity with sensing tube and bracket fixed by gluing, then the device complexity is reduced and ease of manufacture is improved, but heat dissipates from joints causing asymmetric heat distribution and zero drift
Solution Approach 1:
The patent extracts the thermal insulation function from the housing structure and implements it through a dedicated thermal insulation layer filling the cavity. This separates the structural support function (housings) from the thermal management function (insulation layer), allowing the housings to be easily assembled while the insulation layer prevents heat dissipation at joints, thereby resolving the contradiction between ease of manufacture and measurement precision
Solution Approach 2:
The patent introduces asymmetric thermal insulation treatment by filling the cavity with thermal insulation material, which creates a thermal barrier that compensates for the asymmetric heat dissipation paths through glued joints. This asymmetric insulation approach balances the overall heat distribution, preventing zero drift while maintaining the simple glued assembly structure
2Measurement precision
If thermal insulation layer is added to wrap windings and fill cavity, then heat distribution symmetry is improved and zero drift is reduced, but device complexity increases
Solution Approach 1:
The patent merges the thermal insulation function with the existing cavity structure by filling the cavity with thermal insulation material. This combines the structural cavity (already present for housing the sensing tube) with the thermal insulation function, avoiding the need for separate insulation components and reducing overall device complexity while still achieving symmetric heat distribution
Solution Approach 2:
The patent applies thermal insulation locally at critical heat dissipation points - specifically filling the cavity around the sensing tube windings and covering joint areas. This localized insulation approach targets the specific problem areas causing asymmetric heat distribution without insulating the entire device, thereby minimizing the increase in device complexity while effectively improving measurement precision
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 effectively reduces zero drift, improving precision and repeatability of gas mass flow controllers, enhancing their overall performance and production efficiency.
Implementation Method 1
the thermal insulation layer wraps the windings, the sensing tube wrapped by the thermal insulation layer is disposed in the mounting groove
Data Source
AI summary
A fluid measurement sensor and a mass flow controller are provided. The fluid measurement sensor includes a sensor base, a cover plate, a housing, a sensing tube, and a thermal insulation layer; the housing is connected to the sensor base, the cover plate is connected to the housing from one side of the housing, an inner sidewall of the housing is provided with a first half groove, an inner sidewall of the cover plate is provided with a second half groove, and the first half groove and the second half groove form a mounting groove; and the sensing tube is provided with windings wound round the sensing tube, the sensing tube wrapped by the thermal insulation layer is disposed in the mounting groove, and two ends of the sensing tube penetrate through the sensor base.