Thermal Flow Meter Circuit Package Protrusion Design
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Solution Overview
Problem
Conventional thermal flow meters for measuring air flow and temperature in internal combustion engines face reliability issues due to independently arranged measurement elements and electrical connections, which can lead to decreased accuracy and increased susceptibility to environmental factors like temperature changes and vibration.
Innovation Solution
A thermal flow meter design incorporating a bypass passage for air flow measurement and a temperature detecting portion, where the air flow measurement circuit and temperature sensing components are housed in a resin-encased circuit package with a protrusion shape that minimizes fluid resistance and heat transfer, enhancing measurement accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If measurement elements and electrical connections are arranged independently within the measurement target gas, then the device can perform separate air flow and temperature measurements, but the reliability decreases due to increased susceptibility to environmental factors and measurement errors
Solution Approach 1:
The patent combines the air flow measurement circuit and temperature detecting portion into a single integrated circuit package. This merging of previously separate measurement elements into one unified structure reduces the number of independent electrical connections and minimizes exposure to environmental factors, thereby improving reliability while maintaining separate measurement capabilities for air flow and temperature.
Solution Approach 2:
The circuit package serves multiple functions by housing both the air flow measurement circuit and temperature detecting portion in a single integrated unit. This multi-functional design allows the device to perform both air flow and temperature measurements simultaneously with improved reliability, as the unified structure reduces susceptibility to environmental interference compared to separate independent measurements.
2Reliability
If the temperature detecting portion is integrated into the circuit package, then reliability improves, but the protrusion shape requires careful design to minimize fluid resistance and heat transfer
Solution Approach 1:
The protrusion of the temperature detecting portion is designed with a curved surface instead of a flat or angular shape. This curved geometry minimizes fluid resistance by allowing smoother flow around the protrusion and reduces heat transfer from the circuit package body, while still providing the necessary structural integration for reliability.
Solution Approach 2:
The protrusion shape is specifically optimized at the critical interface between the circuit package and the measurement target gas. By concentrating the design effort at this local area with the appropriate curvature and surface characteristics, the patent achieves reliable integration without requiring complex modifications to the entire circuit package structure.
3Object-affected harmful factors
If the protrusion is designed with a shape thicker at the root and narrower at the leading end, then fluid resistance and heat transfer are minimized, but manufacturing precision requirements increase
Solution Approach 1:
The protrusion is designed with specific dimensional parameters that optimize the balance between minimizing fluid resistance and heat transfer. By carefully selecting the thickness at the root and the taper toward the leading end, the patent achieves favorable flow characteristics and thermal isolation while keeping the manufacturing precision requirements within acceptable limits through appropriate parameter selection.
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 achieves high reliability and accuracy in measuring air flow and temperature, effectively addressing the limitations of conventional systems by reducing measurement errors and maintaining performance under varying environmental conditions.
Implementation Method 1
a circuit package having an air flow measurement circuit for measuring an air flow by carrying out heat transfer in relation to the measurement target gas flowing in the bypass passage
Implementation Method 2
a temperature detecting portion which senses a temperature of the measurement target gas
Data Source
AI summary
A thermal flow meter has a bypass passage for taking in and flowing measurement target gas flowing in a main passage, a circuit package having an air flow measurement circuit for measuring an air flow by carrying out heat transfer in relation to the measurement target gas flowing in the bypass passage, and a temperature detecting portion. A case is provided with an external terminal outputting electric signals indicating the air flow and the temperature of the measurement target gas and supports the circuit package. Resin contains the air flow measurement circuit and the temperature detecting portion. The temperature detecting portion has a protrusion which protrudes out of a circuit package main body, and the protrusion is formed into a shape which is thicker in its root than in its leading end portion and its neck portion is narrower little by little toward the leading end.