Alternating Thermal Load Gas Sensor
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Solution Overview
Problem
The existing gas sensor configuration, which heats only the reference element at non-detection timing, creates a difference in the number of heating cycles between the detection and reference elements, making it difficult to reduce the thermal history difference between them effectively.
Innovation Solution
The gas sensor alternates temperature loads between the detection and reference elements, with the reference element having a higher load in one period and the detection element in another, allowing their thermal histories to coincide, and calculates gas concentration based on the potential at their connection point during these periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If only the reference element is heated at non-detection timing, then the reference element's temperature is adjusted, but the detection element and reference element develop different thermal histories
Solution Approach 1:
The patent implements periodic alternating heating of the detection element and reference element. During odd time periods, the detection element is heated while the reference element is not; during even time periods, the reference element is heated while the detection element is not. This periodic alternation ensures both elements experience similar thermal cycles over time, reducing thermal history differences and improving measurement stability.
Solution Approach 2:
Instead of continuously heating only the reference element to adjust its temperature, the patent inverts the approach by alternately heating the detection element and reference element in different time periods. This inversion ensures both elements undergo comparable thermal processing, eliminating the thermal history disparity caused by selective heating.
2Measurement precision
If the detection element and reference element are heated to different temperatures, then gas detection sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent uses periodic alternating heating where the detection element and reference element are heated to different temperatures during different time periods. During odd periods, the detection element is heated to a higher temperature for sensitive gas detection while the reference element is heated to a lower temperature. During even periods, this pattern reverses. This periodic action maintains high detection sensitivity while reducing overall power consumption compared to continuous high-temperature heating of both elements.
Solution Approach 2:
The heating temperatures of the detection element and reference element are dynamically adjusted over time rather than maintaining constant high temperatures. The system switches between different heating states, optimizing the balance between detection sensitivity and power consumption by heating each element to different temperatures at different times.
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 approach effectively reduces the thermal history difference between the detection and reference elements, stabilizing the gas sensor's performance and improving detection accuracy and sensitivity, particularly for CO2 detection.
Implementation Method 1
a first heater resistor MH1 that heats the first thermistor Rd1
Implementation Method 2
a first thermistor Rd1 having a negative resistance temperature coefficient
Data Source
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AI summary
An object of the present invention is to reduce, in a gas sensor having a structure in which a detection element and a reference element are connected in series, the difference in temperature load between the detection element and the reference element easily and more accurately. A gas sensor 10 according to the present invention includes a first thermistor Rd1 as a detection element, a second thermistor Rd2 as a reference element, a first heater MH1 for heating the first thermistor Rd1, a second heater MH2 for heating the second thermistor Rd2, and a control circuit 20 that heats the first and second heaters MH1, MH2 such that the second thermistor Rd2 has a higher temperature than the first thermistor Rd1 in a first period of time and that the first thermistor Rd1 has a higher temperature than the second thermistor Rd2 in a second period of time. According to the present invention, the difference in thermal history between the first and second thermistors Rd1, Rd2 by repeating the first and second periods of time.