UWS Sensor Calibration via Installed Sound Propagation
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Solution Overview
Problem
Existing UWS quality sensors in motor vehicles face challenges in achieving the required ±1% mass fraction measuring accuracy due to installation-induced length changes and geometric influences of the reservoir, leading to false alarms and potential motor vehicle shutdowns.
Innovation Solution
A calibration method for UWS quality sensors that adapts to the installed situation and temperature influences, using a computing unit to store correction measures specific to each UWS supply tank shape, ensuring accurate urea concentration monitoring by calibrating the sensor after initial startup and considering sensor features for precise adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UWS quality sensors are calibrated during manufacture, then initial measurement accuracy is achieved, but installation-induced length changes cause accuracy degradation
Solution Approach 1:
The system performs preliminary calibration actions during manufacture, then automatically recalibrates after installation by detecting sound propagation times in the installed state. This preliminary calibration followed by post-installation adaptation resolves the contradiction between initial accuracy and long-term reliability.
Solution Approach 2:
The system continuously monitors sound propagation times and compares them against reference values to detect deviations caused by installation. This feedback mechanism enables automatic correction of measurement accuracy issues that arise after installation, maintaining long-term reliability.
2Ease of manufacture
If calibration is performed before installation, then manufacturing process is simplified, but installation-induced geometric changes invalidate the calibration
Solution Approach 1:
Basic calibration is performed during manufacture to simplify the manufacturing process, then post-installation calibration is automatically performed to account for geometric changes. This two-stage approach maintains both manufacturing simplicity and installed-state accuracy.
Solution Approach 2:
The system changes calibration parameters based on the installation state by detecting sound propagation times in the installed configuration. This allows the calibration to adapt to geometric changes while maintaining measurement precision in the final installed state.
3Measurement precision
If temperature influences on sensor are considered, then measurement accuracy under varying conditions is improved, but system complexity increases
Solution Approach 1:
The system incorporates temperature sensing and uses temperature values as feedback to adjust calibration parameters. This feedback loop compensates for temperature influences on sound propagation, improving accuracy under varying conditions without requiring complex mechanical adjustments.
Solution Approach 2:
The calibration parameters are dynamically changed based on temperature measurements. By adjusting the conversion rule according to temperature, the system compensates for thermal effects on sound propagation time while maintaining a relatively simple system architecture.
4Measurement precision
If correction measures are adapted to different tank shapes, then measurement accuracy across various installations is improved, but data storage and processing requirements increase
Solution Approach 1:
The system applies local quality by storing correction measures specific to different tank shapes (e.g., correction values for cylindrical vs. rectangular tanks). This allows accurate compensation for installation-specific geometric influences while keeping the data structure organized and manageable.
Solution Approach 2:
The calibration system is designed to be universal by accommodating multiple tank shapes through a standardized data structure that can store different correction measures. A single calibration module handles various tank geometries, reducing the need for separate calibration systems for each tank type.
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
Ensures long-term accurate monitoring of UWS quality without additional production steps, preventing false alarms and maintaining system reliability by adapting the conversion rule based on initial startup conditions and sensor identity.
Implementation Method 1
comprises ultrasonic sensors, by means of which the sound propagation time over a predefined distance is detected, and the urea content of the UWS is derived from the detected propagation time
Implementation Method 2
the ultrasonic sensor or transmitter and a sound reflector which is set up for this purpose are arranged in the medium at a defined spacing from one another
Data Source
AI summary
The present invention relates to a method for calibrating a UWS quality sensor arranged in a motor vehicle. In the method, the calibration of the UWS quality sensor takes place in an installed situation of the UWS quality sensor in the UWS tank.