Virtual Sensor for Diesel Exhaust Fluid Quality
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Solution Overview
Problem
Existing physical sensors for measuring diesel exhaust fluid (DEF) quality in internal combustion engine aftertreatment systems are prone to failures due to aging, permeation, and environmental conditions, leading to inaccurate measurements and increased costs.
Innovation Solution
A virtual sensor system that determines reductant quality by analyzing NOx measurement data from multiple sensors, considering enablement conditions such as reductant fill, machine start, and sensor rationality, to generate a reductant quality value and output a pass, fail, or defer decision without the need for a dedicated physical sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical sensors are used to measure DEF quality, then measurement capability is provided, but reliability deteriorates due to aging, permeation, and environmental conditions
Solution Approach 1:
The patent creates a virtual sensor that copies the measurement function of physical DEF quality sensors by using NOx sensor data and engine operating parameters. Instead of relying on a physical sensor that直接接触 the harsh environment, the virtual sensor replicates the quality assessment capability through computational modeling, thereby eliminating the reliability issues associated with physical sensor degradation while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical/physical sensing system with a computational/software-based system. The virtual sensor uses algorithms that process NOx measurements and engine parameters to infer DEF quality, substituting the physical chemical sensing mechanism with a mathematical model. This substitution eliminates the physical sensor's vulnerability to environmental factors while preserving the measurement capability.
2Measurement precision
If dedicated physical DEF quality sensors are installed, then DEF quality detection is enabled, but device complexity and cost increase
Solution Approach 1:
The patent makes existing NOx sensors and engine control units perform multiple functions: their primary function of monitoring NOx emissions is maintained, and additionally, they serve as the basis for the virtual DEF quality sensor. By reusing existing hardware and data infrastructure, the system achieves DEF quality detection without adding dedicated physical sensors, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent merges the DEF quality measurement function with the existing exhaust monitoring system. The virtual sensor integrates NOx sensor data, engine operating parameters, and chemical reaction models into a unified computational framework. This merging eliminates the need for separate physical DEF quality sensing hardware, reducing system complexity while achieving the measurement objective through combined data processing.
3Reliability
If physical sensors are used for reductant quality measurement, then quality monitoring is achieved, but loss of time occurs due to sensor failures and replacements
Solution Approach 1:
The virtual sensor creates a software-based copy of the quality monitoring function that operates without physical components subject to failure. By using computational algorithms instead of physical sensors, the system eliminates the need for sensor replacement and calibration maintenance, thereby eliminating downtime associated with physical sensor failures while maintaining continuous reliable quality monitoring.
Solution Approach 2:
The virtual sensor system is self-maintaining in the sense that it uses existing sensor data and computational resources already present in the engine control system. It requires no separate calibration procedures, no physical replacement, and automatically adapts to changing operating conditions through its computational model, thereby eliminating the time loss associated with physical sensor maintenance cycles.
Data Source
AI summary
A method for estimating a quality of reductant in an engine aftertreatment system for an engine using a virtual sensor, the method comprising: determining whether an enablement condition is met, wherein the enablement condition is one or more of: a reductant fill condition determined based on data received from one or more float sensors associated with the engine; a machine start condition determined based on machine speed data obtained from a speed sensor associated with the engine; and/or a rationality check condition determined based on data associated with a fault of one or more sensors associated with the engine; upon determining that the enablement condition is met, receiving NOx measurement data obtained from at least one NOx sensor; generating a reductant quality value based on the NOx measurement data; and outputting a reductant quality determination based on the reductant quality value.