Gas Sensor Element Insulating Layer Noise Reduction
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Solution Overview
Problem
Conventional nitrogen oxide (NOx) sensors with laminar structures suffer from signal noise interference when a voltage is applied to the heater element, leading to fluctuations in output values and reduced accuracy in measuring NOx concentrations in exhaust emissions.
Innovation Solution
Incorporating an electrically insulating layer with a total content of 2.5-5 wt% metal oxide, preferably alumina or alumina and silica, around the heater element to increase resistance and mitigate signal noise, while using a laminar structure with multiple electrodes and pumping means to detect oxygen partial pressures accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a voltage is applied to the heater element to heat the sensor layer, then the sensor can operate at the required temperature for detection, but signal noise is generated causing fluctuations in output values and reduced measurement accuracy
Solution Approach 1:
An electrically insulating layer is introduced as an intermediary between the heater element and the sensor layer. This insulating layer prevents direct electrical contact and signal interference while still allowing thermal energy to pass through and heat the sensor layer to the required operating temperature.
Solution Approach 2:
The heater layer is constructed as a composite structure comprising a heater element, an electrically insulating layer, and a porous body layer. This composite design combines materials with different properties: the heater element for heat generation, the insulating layer for electrical isolation, and the porous body for gas permeability and structural support.
2Adaptability or versatility
If the frequency of voltage applied to the heater element is reduced to match digital control circuit requirements, then the control system becomes more compatible with digitalization, but fluctuations in output values become larger
Solution Approach 1:
The electrically insulating layer acts as a mediator that isolates the sensor layer from electrical interference caused by the heater element. This isolation ensures that even when voltage frequency is reduced for digital control compatibility, the sensor output remains stable and free from noise-induced fluctuations.
3Use of energy by moving object
If the heater element is directly connected to the sensor layer for efficient heating, then heat transfer is maximized, but electrical interference and signal noise occur
Solution Approach 1:
The heater layer is designed as a composite structure with multiple functional layers. The electrically insulating layer and porous body layer are positioned between the heater element and the sensor layer, creating a composite material system that simultaneously achieves thermal conduction while blocking electrical interference and signal noise.
Solution Approach 2:
The porous body layer serves as an intermediary medium that allows thermal energy to pass through to heat the sensor layer while preventing direct electrical contact and signal interference between the heater element and the sensor layer.
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 solution effectively reduces signal noise interference, enabling high-accuracy and stable detection of NOx concentrations by enhancing the resistance between the heater element and sensor layer, thus improving the overall measurement precision.
Implementation Method 1
Incorporating an electrically insulating layer with a total content of 2.5-5 wt% metal oxide, preferably alumina or alumina and silica, around the heater element to increase resistance and mitigate signal noise
Implementation Method 2
By supplying an electric current to the heater element, at least a portion of the sensor layer at which the pair of electrodes for measuring the electromotive force are provided is heated to a prescribed temperature
Implementation Method 3
first oxygen pumping means to control an oxygen partial pressure in the first internal space, second oxygen pumping means to pump the oxygen out of the second internal space
Implementation Method 4
at least one pair of electrodes arranged to measure an electromotive force based on a difference in an oxygen concentration between atmospheres, for the purpose of detecting the oxygen concentration in the atmosphere
Data Source
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AI summary
The present invention provides a gas sensor element capable of restraining signal noise generated when an electric current is supplied to a heater element of a heater layer and permitting an electromotive force value to be obtained with high accuracy and high stability. The gas sensor element comprises: a sensor layer in which at least one pair of electrodes (28, 39) are provided in a solid electrolyte (4a-4d) for measuring an electromotive force based on a difference in an oxygen concentration between atmospheres; and a heater layer (42) which includes a heater element (44) with a heat generating portion and an electrically insulating layer (43) disposed so as to enclose the heater element and which is configured to heat, by an electric current supplied to the heater element, at least a portion of the solid electrolyte at which the at least one pair of electrodes are provided, the sensor layer and the heater layer being laminated integrally on each other, wherein the electrically insulating layer (43) contains at least one metal oxide selected from the group consisting of alkali metal oxide and alkaline earth metal oxide.