3D Electrode Urea Sensor for SCR System
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Solution Overview
Problem
Existing methods for identifying urea concentration in vehicle urea solutions for SCR systems are inadequate, leading to potential NOx emission standard exceedance and system damage due to imprecise urea concentration measurements.
Innovation Solution
A urea concentration identification device with a three-dimensional structure featuring a substrate, circular lower electrode, dielectric layer, and patterned upper electrode, which applies a sine-wave AC signal to differentiate impedance values based on urea solution concentrations, utilizing a database to correlate impedance with concentration through frequency scanning and electrical interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional two-electrode measurement structure is used, then the device structure is simple, but the electrical interaction with urea solution is insufficient leading to poor identification quality
Solution Approach 1:
The patent transitions from a conventional two-electrode planar measurement structure to a three-electrode structure with electrodes arranged in a triangular configuration. This dimensional change in electrode arrangement enhances the electrical interaction field with the urea solution, improving measurement precision while maintaining reasonable structural complexity
Solution Approach 2:
The patent introduces a dielectric layer selectively positioned between specific electrode pairs to enhance local electrical interaction. This localized modification improves the sensitivity of urea concentration detection in specific measurement zones without requiring complete structural redesign, thus improving identification quality with controlled complexity increase
2Measurement precision
If the electrode-solution interaction area is increased, then the electrical interaction strength is improved, but the device structure becomes more complex
Solution Approach 1:
The patent employs a three-dimensional electrode arrangement with vertical stacking and triangular horizontal configuration, creating a three-electrode structure that increases the effective interaction volume with urea solution. This spatial arrangement enhances electrical interaction strength by utilizing multiple dimensions rather than expanding only in the planar area
Solution Approach 2:
The dielectric layer is positioned within the electrode structure to create nested configurations that concentrate the electrical field in specific regions. This nesting approach increases interaction strength in targeted zones without proportionally increasing overall device complexity
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
Accurately identifies urea concentrations by enhancing electrical interaction and signal response, improving identification quality and preventing NOx emission exceedance and system damage.
Implementation Method 1
urea solutions of different concentrations have different electrical interactions with electrodes of the urea concentration identification device
Implementation Method 2
different impedance values are output by the urea concentration identification device
Implementation Method 3
a capacitor structure is formed on the substrate. The capacitor structure includes a circular lower electrode, a dielectric layer and a patterned upper electrode
Data Source
AI summary
A urea concentration identification method is provided. By providing an identical sine-wave AC signal to each of the urea concentration identification devices placed in urea solutions of different concentrations, different impedance values are output by the urea concentration identification devices since the urea solutions of different concentrations have different electrical interactions with the electrodes of the urea concentration identification device. Differences of the impedance output by the urea concentration identification device function as a data set for determining the concentration of the urea solution to be determined.