NOx Sensor Using Dual Sensitivity Elements for NO and NO2 Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing NOX detection elements can only measure the overall concentration of NOX, failing to individually detect the concentrations of NO and NO2 within the gas.
Innovation Solution
A NOX concentration detection apparatus and method utilizing two element sections with different sensitivity ratios to NO and NO2 concentrations, allowing for the calculation of individual NO and NO2 concentrations through distinct current measurements and sensitivity differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single detection element is used to measure NOX concentration, then the overall NOX concentration can be detected, but the individual concentrations of NO and NO2 cannot be detected separately
Solution Approach 1:
The invention divides the detection task into two separate detection elements, each with different sensitivity ratios to NO and NO2. The first detection element has a sensitivity ratio of approximately 1:1, while the second has a sensitivity ratio of approximately 1:4. By segmenting the detection function and using the combined outputs of both elements, the system can mathematically resolve the individual concentrations of NO and NO2, thereby preventing loss of component information while maintaining overall detection capability.
2Measurement precision
If two detection elements with different sensitivity ratios are used, then individual NO and NO2 concentrations can be detected, but the device complexity increases
Solution Approach 1:
Both detection elements are designed with the same basic structure and can detect NOX concentration, but they differ in their sensitivity ratios. This multi-functional design allows each element to serve as a NOX detector while simultaneously providing differentiated sensitivity responses that enable individual component analysis. The universal detection capability combined with differentiated sensitivity reduces the need for completely separate detection systems for NO and NO2.
Solution Approach 2:
The invention changes the sensitivity ratio parameter of the detection elements to achieve different detection characteristics. The first detection element operates with a sensitivity ratio of approximately 1:1 (NO:NO2), while the second operates with a sensitivity ratio of approximately 1:4. This parameter variation allows the system to differentiate between NO and NO2 concentrations using the same type of detection element, reducing device complexity compared to using fundamentally different detection technologies.
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
Enables the precise detection of NO and NO2 concentrations within the gas, overcoming the limitations of prior art by providing separate sensitivity ratios for each component of NOX.
Implementation Method 1
a first solid electrolyte member (111) having first and second surfaces opposing each other with a first measurement chamber (101) therebetween; a first pair of electrodes (112, 113) provided on the first and second surfaces of the first solid electrolyte member (111), respectively
Implementation Method 2
a first diffusion resistor section (103) which restricts flow of the object gas therethrough, that is introduced into the first measurement chamber (101)
Implementation Method 3
NO is decomposed to nitrogen and oxygen by the catalytic action of an electrode formed of noble metal such as Pt or Rh
Implementation Method 4
Oxygen contained in the exhaust gas introduced into the first measurement chamber is pumped out of the first measurement chamber to the outside by a first pump cell
Data Source
AI summary
An apparatus and method for individually detecting NO and NO2 concentrations as NOX components of an object gas. An NO concentration corresponding value is obtained from a first detection element not having a reduction section. An NO concentration corresponding value is obtained from a second detection element having a reduction section, and having an NO2/NO sensitivity ratio greater than that of the first detection element. The difference ΔC between the NO concentration corresponding values of the two detection elements is obtained, and divided by the difference ΔS between the NO2/NO sensitivity ratios of the two detection elements, whereby an NO2 concentration corresponding value is obtained. A value obtained by multiplying the NO2 concentration corresponding value by the NO2/NO sensitivity ratio of the second detection element is subtracted from the NO concentration corresponding value of the second detection element, whereby an NO concentration corresponding value is obtained.