Physical Quantity Measurement Device Housing Resistivity Control
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Solution Overview
Problem
Physical quantity measurement devices, such as those measuring intake air flow rate in internal combustion engines, face accuracy deterioration due to foreign matter adhesion and dielectric breakdown, which affects detection accuracy and efficiency.
Innovation Solution
A physical quantity measurement device with a bypass flow channel, a detection unit, and a housing having a specific volume resistivity range (1.0×10^11 to 1.0×10^14 Ωcm) to facilitate dielectric breakdown and discharge of negative charges to ground, preventing foreign matter adhesion and maintaining detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the housing material has high insulating properties (high volume resistivity), then electrical insulation is improved, but foreign matter adhesion increases and detection accuracy deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the volume resistivity of the housing material to a specific range (1.0×10^11 to 1.0×10^14 Ωcm). This controlled parameter adjustment balances electrical insulation requirements with prevention of foreign matter adhesion, resolving the contradiction between insulation performance and detection accuracy.
Solution Approach 2:
The patent employs composite materials by combining insulating resin base materials with conductive fillers (carbon black, carbon fiber, or metal powder) in specific proportions. This creates a composite housing material that provides both necessary electrical insulation and controlled surface conductivity to prevent foreign matter accumulation, simultaneously addressing both requirements.
2Reliability
If the housing material has high insulating properties, then electrical insulation is improved, but dielectric breakdown occurs and negative charges accumulate
Solution Approach 1:
The patent applies parameter changes by optimizing the volume resistivity of the housing material to a specific range (1.0×10^11 to 1.0×10^14 Ωcm). This controlled parameter adjustment balances electrical insulation requirements with prevention of foreign matter adhesion, resolving the contradiction between insulation performance and detection accuracy.
Solution Approach 2:
The patent employs composite materials by combining insulating resin base materials with conductive fillers (carbon black, carbon fiber, or metal powder) in specific proportions. This creates a composite housing material that provides both necessary electrical insulation and controlled surface conductivity to prevent foreign matter accumulation, simultaneously addressing both requirements.
3Reliability
If the housing material has high insulating properties, then electrical insulation is improved, but detection accuracy deteriorates due to foreign matter adhesion
Solution Approach 1:
The patent applies parameter changes by optimizing the volume resistivity of the housing material to a specific range (1.0×10^11 to 1.0×10^14 Ωcm). This controlled parameter adjustment balances electrical insulation requirements with prevention of foreign matter adhesion, resolving the contradiction between insulation performance and detection accuracy.
Solution Approach 2:
The patent employs composite materials by combining insulating resin base materials with conductive fillers (carbon black, carbon fiber, or metal powder) in specific proportions. This creates a composite housing material that provides both necessary electrical insulation and controlled surface conductivity to prevent foreign matter accumulation, simultaneously addressing both requirements.
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 suppresses foreign matter adhesion to detection units, stabilizes measurement results, and enhances the intake efficiency by preventing loss and adverse effects on other sensors, thereby improving the overall performance of the airflow meter.
Implementation Method 1
A volume resistivity of the flow channel forming portion is included in the range of 1.0×10^11 (1.0×10 to the 11th power) Ωcm to 1.0×10^14 (1.0×10 to the 14th power) Ωcm
Implementation Method 2
facilitate dielectric breakdown and discharge of negative charges to ground, preventing foreign matter adhesion
Data Source
AI summary
A physical quantity measurement device that measures a physical quantity of a fluid includes a bypass flow channel through which a fluid flows, a physical quantity detection unit for detecting a physical quantity of the fluid in the bypass flow channel, a detection unit having a detection terminal electrically connected to the physical quantity detection unit, a housing having a flow channel forming portion having an insulating property and forming a bypass flow channel and a terminal accommodating portion having an insulating property and accommodating a detection terminal, and a ground portion connecting the flow channel forming portion to a ground. A volume resistivity of the flow channel forming portion is included in the range of 1.0×1011 (1.0×10 to the 11th power) Ωcm to 1.0×1014 (1.0×10 to the 14th power) Ωcm.