Ultrasound Urea Sensor Temperature Gradient Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing SCR systems face challenges in reliably determining the concentration of urea in AdBlue solutions, leading to inefficient nitrogen oxide reduction due to incorrect dosing, and potential errors in identifying urea content or contamination.
Innovation Solution
An ultrasound-based urea concentration sensor measures the transit time of ultrasonic pulses in a heated urea solution, using temperature gradients to accurately determine urea concentration, avoiding erroneous interpretations and allowing for selective detection based on nitrogen oxide thresholds, thereby optimizing urea dosage and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single temperature measurement is used to determine urea concentration, then the measurement process is simple and fast, but the concentration determination becomes unreliable due to identical sound speeds at different temperatures for solutions with different urea contents
Solution Approach 1:
The patent applies parameter changes by measuring ultrasonic transit time at multiple temperatures (at least two different temperatures) rather than a single temperature. This temperature parameter variation allows the system to detect concentration changes that would be indistinguishable at a single temperature, as different urea concentrations produce different temperature-dependent sound speed profiles. The control unit compares measurements across temperatures to reliably determine actual urea concentration.
2Measurement precision
If the urea solution is continuously heated to maintain optimal temperature for concentration measurement, then measurement reliability is improved, but energy consumption increases significantly
Solution Approach 1:
The patent implements periodic action by heating the urea solution only temporarily during concentration measurement cycles rather than maintaining continuous heating. The system heats the solution to a predetermined temperature, performs the ultrasonic concentration measurement at that temperature, then allows the solution to cool. This periodic heating approach achieves reliable temperature-controlled measurements while significantly reducing energy consumption compared to continuous heating.
Solution Approach 2:
The system performs preliminary heating of the urea solution to a predetermined temperature before conducting the concentration measurement. This preliminary action ensures the solution is at the optimal temperature for accurate measurement without requiring continuous energy input, as the heating is completed in advance of the actual measurement process.
3Reliability
If the urea concentration sensor measures transit time at multiple temperatures, then the gradient-based concentration determination becomes computationally more complex, but the reliability of detecting contamination and stretching improves
Solution Approach 1:
The patent applies feedback by using the control unit to compare the measured gradient of ultrasonic transit time with respect to temperature against expected gradient values for proper AdBlue® concentration. The system provides feedback on whether the actual urea concentration matches the required specification, enabling detection of stretching (water addition) or contamination. This feedback mechanism improves reliability by validating measurements against known reference gradients.
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 method provides a reliable and computationally efficient determination of urea concentration, preventing errors in urea content detection and minimizing energy usage by selectively heating only when necessary, ensuring precise urea dosage and maintaining low nitrogen oxide emissions.
Implementation Method 1
an ultrasound-based urea concentration sensor, the measurement signal of which is representative of a transit time of an ultrasonic pulse along a predetermined path length in a fluid of the urea solution feed
Implementation Method 2
at least the fluid in a detection area of the urea concentration sensor is heated from a first temperature to a predetermined second temperature
Data Source
Figure 1
Figure 2~3
AI summary
An SCR system has a urea solution supply and an ultrasound-based urea concentration sensor, the measurement signal of which is representative for a propagation time of an ultrasonic pulse along a predetermined path length in a fluid of the urea solution supply. At least the fluid (9) in a detection region of the urea concentration sensor (17) is heated from a predetermined first temperature to a predetermined second temperature. During the heating, the measurement signal is captured at at least a third and fourth temperature and a raw concentration characteristic is established in each case depending on the respective measurement signal, which characteristic is representative for the propagation time of the ultrasonic pulse. A concentration characteristic which is representative for a concentration of urea in the fluid is established depending on the raw concentration characteristics.