Emission Control System Reductant Quality Monitoring
Solution Overview
Problem
Selective catalytic reduction (SCR) systems in automotive emission control face challenges in detecting operator tampering with reductant fluids, such as urea, which can lead to ineffective emissions reduction, and existing urea concentration sensors increase vehicle costs and diagnostic issues, with limited availability.
Innovation Solution
A logic-driven method using existing system infrastructure to monitor reductant quality by determining pre- and post-refill operating conditions, detecting changes in these conditions to identify potential tampering or modifications, and correlating them with engine or vehicle operating conditions to detect undesirable fluid entry without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a urea concentration sensor is attached to the reductant storage device opening to detect tampering, then detection capability is improved, but vehicle cost increases and diagnostic issues arise
Solution Approach 1:
The system uses existing sensors (NOx sensor, temperature sensor, pressure sensor) to monitor and detect reductant quality changes. The existing emission control system components serve dual purposes: their primary function plus quality monitoring, eliminating the need for dedicated quality sensors and reducing system complexity and cost.
Solution Approach 2:
Existing sensors in the emission control system are utilized for multiple functions: NOx sensing for emission control, temperature sensing for thermal management, and now quality detection through pattern recognition. This multi-functionality approach avoids adding dedicated quality sensors, reducing overall system complexity while maintaining detection capability.
2Measurement precision
If a urea concentration sensor is attached to the reductant storage device opening, then detection capability is improved, but diagnostic issues increase
Solution Approach 1:
The system continuously monitors operating conditions (NOx levels, temperature, pressure, flow rate) and compares them against expected patterns. When deviations occur that suggest quality changes, the system provides feedback through diagnostic codes or warnings, enabling easier troubleshooting and reducing diagnostic complexity compared to standalone quality sensors.
Solution Approach 2:
The system uses intermediary parameters (NOx conversion efficiency, temperature-pressure relationships, flow rate patterns) as mediators to indirectly assess reductant quality. This indirect measurement approach through multiple correlated parameters provides more diagnostic information and easier troubleshooting than direct quality sensing.
3Device complexity
If existing system infrastructure is used to monitor reductant quality, then device complexity is reduced, but measurement precision may be limited
Solution Approach 1:
The system monitors multiple operating parameters (NOx concentration, temperature, pressure, flow rate) simultaneously and analyzes their relationships and patterns. By examining changes in multiple parameters rather than a single direct measurement, the system achieves accurate quality detection using existing sensors, maintaining measurement precision without adding hardware.
Solution Approach 2:
The quality assessment is formed as a composite of multiple sensor inputs and operating conditions. By combining information from NOx sensors, temperature sensors, pressure sensors, and flow rate data into a unified quality assessment model, the system achieves accurate detection using the collective information from existing infrastructure rather than relying on a single sensor type.
Data Source
AI summary
A method of operating an internal combustion engine having a reductant delivery and storage system in an emission control system, comprising of correlating a change in a monitored operating condition with a refill event to determine whether a reductant-diluting substance has been added to the reductant storage system; and limiting vehicle operation based on the correlation.