Sensor Arrangement in Physical Quantity Detection Device
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Solution Overview
Problem
Conventional physical quantity detection devices for internal combustion engines face challenges in maintaining detection accuracy due to thermal influences when downsized, as the heat from the intake passage wall transfers to the measuring unit, affecting sensor performance.
Innovation Solution
The device is designed with sensors arranged along the protruding direction of the measuring unit in descending order of temperature influence, minimizing heat conduction from the intake passage wall and optimizing sensor placement to reduce thermal impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the measuring unit is downsized to fit a small-sized internal combustion engine, then the device can be applied to compact engines, but heat from the intake passage wall easily transfers to the leading edge of the measuring unit, increasing thermal influence on the sensor and affecting detection accuracy
Solution Approach 1:
The patent arranges sensors in the protruding direction (longitudinal dimension) of the measuring unit rather than distributing them laterally. This dimensional arrangement allows sensors to be positioned at different distances from the heat source (intake passage wall), creating a gradient where sensors farther from the wall experience less thermal influence, thus maintaining detection accuracy in a downsized device
Solution Approach 2:
Different sensors are positioned at different locations along the protruding direction based on their thermal sensitivity characteristics. Sensors less sensitive to temperature are placed closer to the intake passage wall, while temperature-sensitive sensors are positioned farther away. This localized optimization allows each sensor to operate in its optimal thermal environment, preserving overall measurement precision despite the compact size
2Object-affected harmful factors
If the protrusion length of the measuring unit is shortened to reduce thermal conduction from the intake passage wall, then thermal influence on the sensor is reduced, but the device complexity increases due to the need for specific sensor arrangement configurations
Solution Approach 1:
The measuring unit is segmented into multiple functional zones along its protruding direction, with different sensors assigned to different segments based on their thermal sensitivity. This segmentation allows the shortened measuring unit to maintain effective sensor placement without requiring complex external mounting structures, thereby reducing overall device complexity while minimizing thermal influence
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 thermal influence on sensors, maintaining detection accuracy and reliability even in downsized configurations, while ensuring efficient heat dissipation and improved responsiveness.
Implementation Method 1
a flow sensor that detects a flow rate of the measured gas
Implementation Method 2
an intake air temperature sensor that detects temperature of the measured gas
Implementation Method 3
a pressure sensor that detects pressure of the measured gas
Implementation Method 4
a humidity sensor that detects humidity of the measured gas
Data Source
AI summary
To obtain a physical quantity detection device that can prevent a thermal influence on a sensor due to downsizing. A physical quantity detection device 20 of the present invention includes a measuring unit 213 protruding from an inner wall of a main passage 22 toward a passage center of the main passage. The physical quantity detection device 20 includes at least one of a flow sensor 205 that detects a flow rate of a measured gas 2, an intake air temperature sensor 203 that detects temperature, a pressure sensor 204 that detects pressure, and a humidity sensor 206 that detects humidity, and the sensors are disposed along a protruding direction of the measuring unit 213.