Acoustic Sensor Signal Validation for Reductant Monitoring
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Solution Overview
Problem
Accurate detection of reductant reserves in exhaust gas treatment systems, particularly in SCR devices, is challenging due to inaccuracies in volumetric pump dosing and ammonia slip, leading to inefficient NOx reduction.
Innovation Solution
An acoustic sensor is integrated within the reductant reservoir to generate signals for monitoring reductant quantity, with validation methods using wake-up conditions, reductant flow rate data, ambient temperature, and unfrozen reductant mass to ensure accurate dosing and reduce wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic sensors are used to monitor reductant levels, then measurement capability is improved, but signal accuracy and reliability deteriorate due to environmental interference and sensor drift
Solution Approach 1:
The patent implements a feedback-based signal validation system where acoustic sensor signals are continuously monitored against expected physical relationships. The system uses feedback from temperature sensors, flow rate data, and reservoir level changes to verify acoustic signal plausibility. When signals deviate from expected patterns, the system triggers validation routines to filter out erroneous readings, thereby maintaining measurement precision while ensuring signal reliability.
Solution Approach 2:
The patent applies preliminary action by establishing validation rules and thresholds before acoustic measurements are taken. The system pre-defines acceptable signal ranges, temperature compensation factors, and physical constraint relationships. By preparing these validation criteria in advance, the system can quickly filter unreliable signals without compromising measurement accuracy, resolving the contradiction between precision and reliability.
2Object-generated harmful factors
If reductant dosing is increased to ensure sufficient NOx reduction, then emission control effectiveness is improved, but ammonia slip and reductant wastage increase
Solution Approach 1:
The patent employs feedback control by continuously monitoring actual reductant consumption through acoustic level measurements and comparing it with dosing rates. The system adjusts dosing in real-time based on feedback from reservoir level changes, ensuring that reductant is dosed at optimal rates rather than excessive amounts. This feedback mechanism maintains effective NOx control while minimizing ammonia slip and reductant wastage by matching dosing precisely to actual consumption patterns.
Solution Approach 2:
The patent replaces traditional mechanical volumetric pump dosing with an acoustic-based measurement and control system. Instead of relying on mechanical dosing schedules that may be inaccurate or excessive, the system uses acoustic sensors to continuously monitor reductant levels and infer consumption rates. This substitution enables more precise dosing control, reducing both insufficient dosing (which compromises NOx control) and excessive dosing (which causes ammonia slip and wastage).
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 approach enhances reductant dosing accuracy, reduces ammonia slip, and improves the performance of SCR catalyst models by accurately monitoring and managing reductant levels, thereby effectively reducing NOx emissions.
Implementation Method 1
an acoustic sensor disposed within the reductant capable of generating signals relating to the volume of reductant within the reservoir
Data Source
AI summary
A method for monitoring the reductant quantity in a reservoir method is provided. The reductant is stored within the reservoir for use within an exhaust gas treatment system of a vehicle, and the reservoir comprises an acoustic sensor disposed within the reductant and capable of generating signals relating to the volume of reductant within the reservoir. The method includes generating a first signal for validation after a system wakeup, conducting a wakeup validation using a wakeup condition, wherein the wakeup condition includes determining if the first signal is within a first accuracy threshold relative to a validated signal generated during the previous operating cycle; and conducting a secondary validation for a signal generated after the first signal using one or more secondary validation conditions. The method can further comprise conducting one or more subsequent validations for one or more signals generated after the first signal.