Thermal Flow Meter Fixation Wall Concave Recess Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing thermal flow meters face challenges in accurately setting and maintaining the positional and angular relationships between the air flow sensing portion and the bypass passage, leading to degradation in measurement accuracy due to manufacturing errors and adhesive inconsistencies, which affects the precision of gas flow rate measurement.
Innovation Solution
A thermal flow meter design where the air flow sensing portion is integrally formed with a supporting body using a first resin material, and this supporting body is fixed to a fixation wall using a second resin material, with a storage portion having a concave portion to house the end portion of the supporting body, ensuring precise alignment and reducing the impact of manufacturing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the air flow sensing portion is fixed to the bypass passage using adhesive with predefined positional relationship, then the measurement accuracy can be improved, but it is difficult to define and maintain the positional and angular relationships during bonding and solidification processes
Solution Approach 1:
The patent applies preliminary action by forming a concave portion in the bypass passage before assembling the air flow sensing portion. This pre-formed concave structure serves as a built-in positioning feature that automatically defines the correct positional and angular relationships during assembly, eliminating the need for complex adhesive bonding processes to maintain precision.
Solution Approach 2:
The concave portion acts as an intermediary element between the bypass passage and the air flow sensing portion. It provides a dedicated receiving space that guides and secures the sensing portion in the correct position, mediating the assembly process to ensure precise alignment without relying on adhesive bonding characteristics.
2Ease of manufacture
If the end portion of the air flow sensing portion is exposed in the bypass passage, then the assembly is simplified, but the measurement target gas generates a vortex that reaches the heat transfer surface and degrades measurement accuracy
Solution Approach 1:
The patent applies the nesting principle by placing the air flow sensing portion inside the concave portion of the bypass passage. The sensing portion is nested within the concave structure, which allows the end portion to be contained rather than exposed. This nesting arrangement prevents the generation of vortices by the exposed end while maintaining a compact and simple assembly structure.
Solution Approach 2:
The concave portion converts the potentially harmful effect of the exposed end portion (vortex generation) into a beneficial arrangement. By designing the concave structure to receive and contain the sensing portion, the patent transforms what would be a source of measurement error into a feature that actually prevents vortex formation while simplifying the overall assembly.
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 design enhances the measurement accuracy of the thermal flow meter by minimizing positional and angular discrepancies, resulting in improved detection of gas flow rates with reduced influence from manufacturing errors and adhesive inconsistencies.
Implementation Method 1
a flow rate of the gas is measured by performing heat transfer between the air flow sensing portion and the gas as a measurement target
Implementation Method 2
An elastic adhesive is filled in a gap between the hole of the bypass passage and she air flow sensing portion and a gap of the portion where the sensor assembly is inserted into the casing, so that an elastic force of the adhesive absorbs a linear expansion difference therebetween
Data Source
AI summary
The present invention is to improve measurement accuracy of a thermal flow meter. In a thermal flow meter of the invention, a circuit package 400 includes a processing unit 604 in which a passage 605 and a circuit are disposed. An air flow sensing portion 602 is disposed in the passage 605. A fixing portion 372 is integrally formed with and fixed to the circuit package 400 and forms a bypass passage. The passage 605 of the circuit package 400 is arranged inside the bypass passage. In the bypass passage, a storage portion 384 having a concave portion 383 is formed to face the fixing portion 372. At least a part of the leading end 401 of the circuit package 400 is contained in the concave portion 383 of the storage portion 384.