Thermal Gas Sensor Segmented Heating for Response Speed
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Solution Overview
Problem
Conventional thermal gas sensors face challenges in response speed and accuracy, particularly in measuring humidity for internal combustion engines, due to the need to heat and cool heating members to different temperatures, which affects measurement speed and introduces errors from resistance value degradation over time.
Innovation Solution
A thermal gas sensor design featuring a first heating member and a second heating member, where the second member surrounds the first and is controlled to a constant temperature lower than the first, maintaining a stable temperature around the first member and reducing the impact of ambient temperature variations, allowing for accurate detection of heat conductivity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the same heating member is heated to different temperatures in a time division manner, then power consumption is reduced, but response speed is reduced due to heating and cooling time requirements
Solution Approach 1:
The heating member is divided into two separate heating members: a first heating member for sensing and a second heating member for temperature compensation. This segmentation allows both members to operate simultaneously at different temperatures, eliminating the time-division heating approach while reducing overall power consumption.
Solution Approach 2:
The second heating member acts as an intermediary that provides thermal compensation to the first heating member. By controlling the second heating member's temperature, the system compensates for ambient temperature variations without requiring the first heating member to be repeatedly heated and cooled, thus maintaining fast response speed while reducing power consumption.
2Device complexity
If ambient temperature variations are not compensated, then device complexity is reduced, but measurement precision deteriorates due to temperature-dependent resistance variations
Solution Approach 1:
The second heating member serves as a thermal intermediary that compensates for ambient temperature effects on the first heating member. By maintaining a controlled temperature differential between the two heating members, the system achieves temperature compensation without complex external temperature control systems.
Solution Approach 2:
The system changes the temperature parameter of the second heating member to compensate for ambient temperature variations. By dynamically adjusting the second heating member's temperature based on the detected ambient conditions, the system maintains measurement precision while keeping the overall device structure relatively simple.
3Device complexity
If the heating member is exposed to ambient temperature variations, then device complexity is reduced, but measurement precision deteriorates due to heat loss variations
Solution Approach 1:
The second heating member acts as a thermal intermediary that compensates for heat loss variations caused by ambient temperature changes. By controlling the temperature differential between the two heating members, the system maintains consistent heat conduction measurements without requiring complex insulation or environmental control.
4Device complexity
If a single heating member is used for both sensing and temperature control, then device complexity is reduced, but reliability deteriorates due to resistance value degradation over time
Solution Approach 1:
The single heating member is segmented into two distinct heating members with separate functions: the first heating member for sensing heat conduction changes and the second heating member for temperature compensation. This segmentation improves reliability by preventing resistance degradation in the sensing element while maintaining a relatively simple overall device structure.
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 design enhances response speed and accuracy by maintaining a stable temperature around the first heating member, reducing errors from ambient temperature variations and extending sensor reliability, while simplifying the driving circuit and improving measurement precision.
Implementation Method 1
measure components of a gas to be measured, based on a variation in heat conduction in the gas
Implementation Method 2
the second heating member is controlled to a temperature lower than a temperature to which the first heating member is controlled
Data Source
Figure 1~2
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Figure 4
AI summary
The present invention provides a high-responsiveness and high-accuracy thermal gas sensor configured to enable gas to be analyzed based on a variation in heat conductivity. The thermal gas sensor includes a substrate 2 with a cavity portion 5, a thin-film support 6 stacked in the cavity portion and comprising a plurality of insulating layers 8a and 8b, and a first heating member 3 and a second heating member 4 both sandwiched between the insulating layers in the thin-film support. The second heating member 4 is located around a periphery of the first heating member 3. The first heating member 3 is controlled to a temperature higher than a temperature to which the second heating member 4 is controlled. The concentration of ambient gas is measured based on power applied to the first heating member 3.