Engine Control System for Low Reductant Operation
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Solution Overview
Problem
Existing engine systems face challenges in maintaining compliance with NOx emission regulations when the urea reductant supply is low, as they either require vehicle deactivation or limited operation, which can lead to inconvenient vehicle stranding and non-compliance if the reductant is depleted before reaching a service station or is unavailable at a required rate, such as when frozen.
Innovation Solution
A control system that includes sensors for fuel and reductant levels, communicating with a controller to alter engine operation, ensuring that the remaining fuel is consumed before the reductant, thereby extending vehicle operation until the fuel supply is exhausted, while maintaining NOx compliance through optimized engine performance adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vehicle deactivation is implemented when reductant supply is low, then NOx emission compliance is maintained, but vehicle availability and operational continuity deteriorate
Solution Approach 1:
The system dynamically adjusts engine operating parameters (exhaust gas recirculation rate, injection timing, load distribution) in response to varying reductant levels, transitioning from normal operation to conservation mode as needed. This dynamic adaptation allows the vehicle to maintain compliance while remaining operational, resolving the contradiction between emission reliability and operational availability.
Solution Approach 2:
The system changes operational parameters including increasing exhaust gas recirculation rate, adjusting fuel injection timing, and modifying load distribution between engines. These parameter changes reduce reductant consumption rate and extend operational range, allowing continued operation without compromising emission compliance.
2Reliability
If limited utility operation is implemented with low reductant supply, then NOx emission compliance is partially maintained, but operational flexibility and restart capability deteriorate
Solution Approach 1:
The system provides multiple operational modes (normal mode, conservation mode, and extended range mode) that can be dynamically selected based on reductant levels and operational requirements. This dynamic mode selection maintains adaptability and operational flexibility while ensuring compliance through appropriate parameter adjustments in each mode.
3Duration of action of moving object
If normal engine operation continues with low reductant supply, then vehicle operational continuity is maintained, but reductant consumption rate increases
Solution Approach 1:
The system implements conservation mode by changing key operational parameters: increasing exhaust gas recirculation rate to reduce combustion temperature and NOx formation, adjusting fuel injection timing to optimize combustion efficiency, and modifying load distribution. These parameter changes reduce the reductant consumption rate while extending vehicle operational continuity.
Solution Approach 2:
The system continuously monitors reductant levels and provides feedback to the control system, which automatically adjusts operating parameters to optimize the balance between operational continuity and reductant consumption. This closed-loop feedback control ensures extended range while maintaining compliance.
4Reliability
If exhaust gas recirculation quantity is increased to reduce NOx and reductant consumption, then emission compliance is improved, but engine power output and efficiency deteriorate
Solution Approach 1:
The system dynamically balances exhaust gas recirculation rate with other parameters including fuel injection timing, air intake control, and load distribution. By coordinating these adjustments, the system minimizes the negative impact on power output while achieving the necessary reduction in NOx and reductant consumption for compliance.
Solution Approach 2:
The system implements coordinated parameter changes beyond just exhaust gas recirculation, including optimizing fuel injection timing and pressure, adjusting air intake manifold pressure, and redistributing load between engines. These complementary parameter changes compensate for power loss from increased EGR while maintaining emission compliance.
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 solution allows continued vehicle operation until the fuel supply is depleted, ensuring compliance with emission regulations and preventing inconvenient stranding, even if the reductant supply is low or unavailable at a required rate, such as when frozen.
Implementation Method 1
The reductant reacts with NOx in the exhaust gas to form H2O and N2
Implementation Method 2
a gaseous or liquid reductant (most commonly a urea/water solution) is added to the exhaust gas stream of an engine and is absorbed onto a catalyst
Data Source
AI summary
A control system for a power unit having a supply of fuel and a supply of reductant is disclosed. The control system may have a first sensor associated with the supply of fuel to generate a signal indicative of a quantity of fuel remaining. The control system may also have a second sensor associated with the supply of reductant to generate a signal indicative of a quantity of the reductant remaining. The control system may further have a controller in communication with the first and second sensors. The controller may be configured to affect operation of the power unit such that the remaining fuel is consumed before consumption of the remaining reductant.