Flow Sensor Resin Seal Protrusion Design
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Solution Overview
Problem
The existing air flow rate measuring devices face challenges in maintaining measurement stability due to the fluidity of synthetic resin materials used for sealing, which can cause variations in shape and affect airflow around the sensing element, leading to degradation in measurement accuracy.
Innovation Solution
A physical quantity detection device is designed with a housing and cover that form a bypass passage, where a circuit substrate is exposed to detect the flow rate of the measurement target gas, and a synthetic resin material is applied to seal the connection points of the sensor element and connection wire, with a protrusion on the cover to cover part of the resin material, reducing its influence on airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synthetic resin material is applied to seal the connected portion of the sensing element, then protection from pollution and water droplets is improved, but shape variations cause degradation in measurement stability
Solution Approach 1:
A support structure is introduced as an intermediary element between the sensing element and the synthetic resin material. The support structure provides a stable framework that prevents the resin material from directly contacting and deforming the sensing element, thereby maintaining measurement stability while still allowing the resin to provide protective sealing against pollution and water droplets.
Solution Approach 2:
The support structure is strategically positioned only in the critical areas where the sensing element connects to the circuit substrate, providing localized reinforcement exactly where needed. This allows the synthetic resin material to maintain its protective function while the support structure locally prevents shape variations that would affect measurement precision.
2Reliability
If synthetic resin material is used for sealing the connected portion, then protection from pollution products and water droplets is improved, but shape management becomes difficult due to fluidity before curing
Solution Approach 1:
The support structure is installed in advance, before the synthetic resin material is applied. This preliminary action creates a pre-defined framework that guides and constrains the resin material during the sealing process, making shape management easier even though the resin remains fluid. The support structure acts as a mold or guide that ensures consistent shaping.
Solution Approach 2:
The support structure serves as an intermediary between the manufacturing process and the final sealed component. It mediates the interaction between the fluid resin material and the sensing element, providing a stable reference that simplifies shape control during the sealing operation.
3Ease of operation
If the electrically joined portion is exposed into the bypass passage, then connection to circuit substrate is achieved, but the joined portion is vulnerable to pollution products and water droplets
Solution Approach 1:
The support structure acts as an intermediary protective element that allows the sensing element to remain electrically connected to the circuit substrate while shielding the connection area. The support structure creates a protected zone where the electrical connection can function while being shielded from harmful environmental factors.
Solution Approach 2:
The device is segmented into protected and exposed zones. The support structure creates a distinct protected region for the electrical connection, separating it from the bypass passage environment. This segmentation allows different parts of the device to have different exposure levels to pollution and water droplets.
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 effectively reduces the impact of resin material shape variations on airflow, enhancing measurement stability and accuracy by ensuring consistent airflow patterns around the sensing element.
Implementation Method 1
a flow rate detection portion for measuring a flow rate of the measurement target gas by heat transfer between a bypass passage for flowing a part of the measurement target gas taken in from a main passage and the measurement target gas flowing through the bypass passage
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
In order to improve measurement stability of a flow rate detection unit in a physical quantity detection device, a periphery of a synthetic resin material is provided with a protruding section protruding to the cover side, said synthetic resin material sealing a metal wire electrically connecting the flow rate detection unit and a circuit unit to each other, thereby improving the measurement stability. A physical quantity detection device 300 of the present invention is characterized by having a housing 302, a front cover 303 fixed to the housing, a circuit board 400 housed in the housing 302, a flow rate detection unit 602 that detects, in a sub-path 305, the flow rate of a gas to be measured 30 by being attached to the circuit board 400, a connecting wire 404 that electrically connects the flow rate detection unit to the circuit board, and a synthetic resin material 418 that seals a connecting wire-included connection portion between the circuit board and the flow rate detection unit, said front cover 303 having a protruding section 353 covering at least a part of the synthetic resin material by protruding into the sub-path.