Thermal flow rate/flow quantity sensor, and air conditioner
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Solution Overview
Problem
The measurement accuracy of thermal flow velocity and flow rate sensors is limited by the low heat transmission efficiency from the heat generating element to the temperature measuring element due to air interposed between them, which affects the detection speed and accuracy.
Innovation Solution
Introducing a resin with higher heat conductivity than air between the heat generating element and the temperature measuring element to enhance heat transmission efficiency and improve measurement accuracy, while also coating the elements and substrate with resin to protect against dust and moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If air is interposed between the heat generating element and the temperature measuring element, then the sensor structure is simple, but the heat transmission efficiency is low
Solution Approach 1:
The patent introduces resin as an intermediary substance between the heat generating element and the temperature measuring element. This resin fills the gaps and replaces air in the inter-element space, serving as a thermal conductor that efficiently transmits heat from the heat generating element to the temperature measuring element, thereby resolving the contradiction between structural simplicity and heat transmission efficiency.
Solution Approach 2:
The patent changes the physical parameter of the medium between the heat generating element and temperature measuring element from air (low heat conductivity) to resin (high heat conductivity). This parameter change in the interstitial material's thermal conductivity directly improves heat transmission efficiency while maintaining the overall simple sensor structure.
2Measurement precision
If the heat generating element and temperature measuring element are coated with resin, then heat transmission efficiency is improved, but the complexity of manufacturing increases
Solution Approach 1:
The patent merges the resin coating process with the existing manufacturing流程 by applying resin to the heat generating element and temperature measuring element during assembly. This integration of the coating step into the manufacturing process minimizes additional complexity while achieving the desired heat transmission improvement.
3Reliability
If resin is used to coat the elements, then protection against dust and moisture is improved, but the device complexity increases
Solution Approach 1:
The resin coating serves multiple functions simultaneously: it acts as a thermal conductor for heat transmission, and it forms a protective barrier against dust and moisture. This multi-functionality of the resin layer resolves the contradiction by providing both thermal performance and environmental protection without requiring separate protective structures, thereby avoiding increased device complexity.
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 resin coating enhances heat transmission, improves measurement accuracy, and prevents deterioration from dust and moisture, resulting in more precise flow velocity and flow rate measurements.
Implementation Method 1
the resin is interposed between the heat generating element and the temperature measuring element. Such a resin is higher in heat conductivity than air
Implementation Method 2
a heat generating element configured to generate heat in accordance with supply current
Implementation Method 3
a temperature measuring element configured to detect temperature of the heat generated from the heat generating element
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A thermal flow velocity and flow rate sensor 1 includes a substrate 2, a heat generating element 3 mounted on the substrate 2, a temperature measuring element 4 mounted on the substrate 2, and a joint portion 13 made of a resin 10 filled between the heat generating element 3 and the temperature measuring element 4 and thermally connecting the heat generating element 3 and the temperature measuring element 4.