Limiting Current Oxygen Sensor Gas Diffusion Bore Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional limiting current type oxygen sensors face challenges in accurately measuring lower oxygen concentrations due to production complexity, increased costs, and variations in tilt characteristics, which affect measurement accuracy and stability.
Innovation Solution
A limiting current type oxygen sensor with a gas diffusion mechanism that includes an internal space with a distance greater than or equal to the bore diameter of the gas diffusion bore, configured to satisfy specific expressions relating to the Faraday constant, diffusion coefficient, oxygen concentration, and bore dimensions, minimizing diffusion-rate determinateness and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the internal space thickness is made smaller to increase output current for lower oxygen concentration measurement, then the measurement range is extended, but the tilt characteristic becomes non-constant and measurement accuracy deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the gas diffusion mechanism by setting the internal space thickness to be equal to or greater than the bore diameter, which fundamentally alters the diffusion characteristics and restores constant tilt behavior in the voltage-current relationship, thereby improving measurement accuracy
2Measurement precision
If gas diffusion bores are formed through the cap to measure lower oxygen concentrations, then the sensing capability is improved, but the production complexity and cost increase
Solution Approach 1:
The patent merges the gas diffusion function into a single bore structure rather than using multiple separate gas diffusion bores, which simplifies the overall structure and reduces production complexity while maintaining the capability to measure low oxygen concentrations
3Measurement precision
If multiple gas diffusion bores are formed through the cap to satisfy measurement conditions, then the oxygen concentration measurement accuracy is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent extracts the gas diffusion function from multiple complex bore structures and consolidates it into a single bore with appropriately dimensioned internal space, which reduces the cumulative precision requirements and simplifies manufacturing while maintaining measurement accuracy
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 accurate sensing and measurement of oxygen concentrations, even at lower concentrations, while simplifying production and reducing costs by stabilizing the tilt characteristic and minimizing the influence of external perturbations.
Implementation Method 1
The current flowing in the ion conductor 101 of the limiting current type oxygen sensor 100 is based on the migration of oxygen ions
Implementation Method 2
A gas diffusion mechanism, with gas diffusion bores 104, 105 and an internal space 106a to supply a diffusion-rate-determined gas to one electrode 103
Implementation Method 3
A heater 107 is provided on the outside of the cap 106 to set the ion conductor 101 at a monitor temperature of several 100° C.
Data Source
AI summary
A limiting current type oxygen sensor having a gas diffusion mechanism comprising a gas diffusion bore and an internal space communicating with the gas diffusion bore for supplying a diffusion-rate-determined gas. The gas diffusion mechanism may be configured such that an oxygen concentration gradient within the internal space satisfies the expression:1/Ilim=(1/4 FDCo2){(l/S)+(lin/Sin)}based on the Faraday constant (F); a diffusion coefficient (D); an oxygen concentration (Co2); a bore area (S) of the gas diffusion bore; a bore length (l) in the axial direction of the gas diffusion bore; a distance (lin) in the internal space between the first electrode and the inner surface opposed thereto; an effective cross section (Sin) of the internal space; and an output current value (Ilim). This makes it possible to accurately sense and measure the oxygen concentration, even at low oxygen concentrations, and achieve easy producibility and cost reducibility.