Thermal Flow Meter Lead Erosion Protection
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Solution Overview
Problem
The existing thermal flow meters are prone to erosion and water intrusion due to exposed cut end portions of leads, which can lead to measurement inaccuracies and device degradation when used in harsh environments like internal combustion engines.
Innovation Solution
A thermal flow meter design that covers the cut end portion of the lead with a covering portion to prevent water or saltwater adhesion and intrusion, ensuring the integrity of the circuit package and maintaining measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the support frame is cut off to simplify the device structure, then the device complexity is reduced, but the cut end portion of the lead becomes exposed and susceptible to water adhesion and erosion
Solution Approach 1:
A covering portion is introduced as an intermediary element between the exposed cut end portion of the lead and the harmful environment (water, saltwater). This covering portion prevents direct contact between water and the lead, thereby preventing erosion and maintaining reliability while allowing the support frame to be cut off for structural simplification.
Solution Approach 2:
The covering portion acts as a protective shell or film that encapsulates the exposed cut end portion of the lead. This thin protective layer prevents water adhesion and erosion without adding significant structural complexity, resolving the contradiction between simplified device structure and erosion resistance.
2Loss of substance
If the support frame is cut off to reduce material usage, then the loss of substance is reduced, but water can infiltrate through the cut end portion and erode the circuit chip and sensor chip
Solution Approach 1:
The covering portion serves as a protective intermediary that blocks water infiltration pathways at the cut end portion of the lead. This allows the support frame to be cut off for material reduction while the covering portion prevents harmful water from reaching and eroding the circuit chip and sensor chip.
3Ease of manufacture
If the cut end portion is left exposed to maintain ease of manufacture, then the ease of manufacture is improved, but measurement precision deteriorates due to lead erosion
Solution Approach 1:
The covering portion is a simple, inexpensive protective element that can be easily applied during manufacturing. It serves as a disposable or long-lasting protective barrier that prevents lead erosion, thereby maintaining measurement precision without complicating the manufacturing process.
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 solution effectively prevents erosion and intrusion, enhancing the reliability and accuracy of gas flow measurements in challenging conditions, such as those encountered in internal combustion engines.
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
Data Source
AI summary
Provided is a thermal flow meter that can be prevented from being eroded due to adhesion of water or like to a cut end portion of the lead exposed from the mold resin of the circuit package. A thermal flow meter 300 of the present invention is a thermal flow meter having a circuit package 400 formed by mounting a detection element 518 on leads 544 and 545 supported by a support frame 512, sealing with a mold resin, and cutting off the support frame 512, wherein cut end portions 544a and 545a of the leads 544 and 545 exposed from the mold resin of the circuit package 400 by cutting off the support frame 512 is covered by a covering portion 371.