Gas Sensor Device Thermal Calibration for Drift Reduction
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Solution Overview
Problem
Gas sensor devices used in internal combustion engines face challenges in maintaining accurate detection of heating element degradation under wide temperature fluctuations, leading to potential errors in measuring physical quantities like air flow rate and humidity due to temperature differences between resistive layers and heat conduction variations.
Innovation Solution
A gas sensor device is designed with a heat insulating film, a first heater for measuring gas physical quantities, and a reference resistor, along with a second heater that simultaneously heats both, ensuring temperature uniformity and stability through a calibration heater to maintain accurate resistance value detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the heating element is heated to high temperature for long-term use, then detection function is maintained, but the relationship between resistance value and temperature changes causing drift in temperature control
Solution Approach 1:
The patent performs preliminary diagnostic heating of both the detection heater and reference resistor to a predetermined temperature before actual measurement. This preliminary action allows detection of resistance value changes at a known temperature state, enabling identification of degradation trends before they affect normal operation. The diagnostic process is performed periodically to catch drift early.
Solution Approach 2:
The patent changes the temperature parameter by heating both the detection heater and reference resistor to a predetermined diagnostic temperature that differs from the normal operating temperature. This parameter change allows measurement of resistance values under controlled thermal conditions, separating the effects of aging from temperature variations. The resistance values are measured at this elevated temperature to detect degradation.
2Adaptability or versatility
If the sensor device operates in wide temperature range environment, then adaptability is improved, but accuracy in detecting heating element degradation is reduced due to temperature differences between resistive layers
Solution Approach 1:
The patent extracts the temperature influence from the degradation detection process by introducing a reference resistor that is heated separately from the detection heater. The reference resistor serves as a temperature reference that is not affected by the gas detection process. By measuring and comparing resistance values of both elements at the same temperature, the method separates thermal effects from actual degradation, enabling accurate detection despite wide ambient temperature variations.
Solution Approach 2:
The patent creates an asymmetric thermal configuration where the detection heater and reference resistor are heated by different heating elements (first heater and second heater respectively). This asymmetric arrangement allows independent temperature control and measurement of each component, enabling the system to compensate for ambient temperature variations and accurately detect degradation of the detection heater regardless of environmental conditions.
3Ease of operation
If diagnostic measurement is performed at different temperatures, then flexibility in operation is improved, but detection accuracy is reduced due to temperature-dependent resistance changes
Solution Approach 1:
The patent creates thermal equipotentiality by heating both the detection heater and reference resistor to the same predetermined temperature using respective heating elements. This equipotential thermal state ensures that both components are at identical temperature conditions during diagnostic measurement, eliminating temperature differences as a variable. The resistance values are then comparable because they are measured under equivalent thermal conditions, regardless of when or where the diagnostic is performed.
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 enables high-accuracy detection of temporal changes and maintains measurement accuracy over a long period, even under varying temperature conditions, by ensuring the detection and reference resistors are held at a consistent diagnostic temperature, reducing errors and improving diagnostic reliability.
Implementation Method 1
a first heater (detection heater 3) provided on the heat insulating film 8b and measuring physical quantity of gas; a reference resistor (4) formed in a resistive layer same as the first heater (detection heater 3) and formed on the heat insulating film 8b
Implementation Method 2
a sensor device that measures physical quantity such as flow rate of a gas and concentration detects a change in a heat radiation amount from a heating element formed in a sensor element to the gas
Data Source
AI summary
An object of the present invention is to provide a gas sensor device capable of detecting a temporal change with high accuracy and maintaining measurement accuracy over a long period under a temperature environment susceptible to a complicated and wide range of change.The gas sensor device includes: heat insulating films 8a and 8b formed on a substrate 2; a first heater 3 provided on the heat insulating films 8a and 8b and configured to measure physical quantity of gas; and a reference resistor 4 formed in a resistive layer same as the first heater and formed on the heat insulating films 8a and 8b. The gas sensor device further includes a second heater 5 that simultaneously heats the first heater 3 and the reference resistor 4.