Dynamic Lambda Control for Multi-Stage Exhaust Gas Aftertreatment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for exhaust gas aftertreatment in internal combustion engines, particularly with multi-stage systems, fail to adequately account for temperature-dependent conversion behavior of catalytic converters, leading to suboptimal emissions control, especially during starting and cooling phases.
Innovation Solution
A method involving a multi-stage exhaust gas system with multiple three-way catalytic converters and lambda probes, where component temperatures are monitored and used to adapt lambda control, employing natural frequency control to optimize emissions conversion across the entire catalytic converter volume, and including particulate filter regeneration strategies to minimize secondary emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigidly configured lambda control system is used in multi-stage exhaust gas aftertreatment, then the control system structure is simple, but the emission results are suboptimal
Solution Approach 1:
The patent implements a dynamic lambda control system that adapts control parameters based on the thermal state of individual catalytic converters. The control system transitions from a rigid configuration to a dynamic one that adjusts lambda setpoints and control amplitudes according to real-time temperature measurements from multiple lambda probes, thereby optimizing emission results while managing system complexity through structured adaptation strategies.
Solution Approach 2:
The patent changes control parameters (lambda setpoints, control amplitudes, switching frequencies) based on the thermal state of catalytic converters. By monitoring temperatures and adjusting lambda control parameters dynamically, the system optimizes conversion efficiency across different operating conditions, resolving the contradiction between simple control structure and optimal emission results.
2Reliability
If temperature-dependent conversion behavior is not considered, then the control method is simple, but the exhaust gas aftertreatment efficiency is suboptimal
Solution Approach 1:
The patent employs feedback control by monitoring temperatures with lambda probes positioned at different locations in the exhaust system and using this information to adjust lambda control strategies. The feedback mechanism enables the control system to adapt to temperature-dependent conversion behavior, improving aftertreatment efficiency while maintaining manageable complexity through systematic feedback processing.
Solution Approach 2:
The control method becomes dynamic by continuously adapting to temperature conditions. The system adjusts lambda setpoints and control amplitudes based on real-time temperature measurements, enabling optimal conversion efficiency across varying thermal states without requiring overly complex control architecture.
3Productivity
If lambda control is extended to downstream catalytic converters, then the controlled segment is larger, but the control system complexity increases
Solution Approach 1:
The patent segments the exhaust system into multiple controlled zones, each monitored by dedicated lambda probes. By dividing the control task into segments (upstream converter, downstream converter, particulate filter), the system achieves comprehensive coverage while managing complexity through modular control strategies for each segment.
Solution Approach 2:
The lambda control system is designed to serve multiple functions simultaneously: controlling upstream catalytic converter, downstream catalytic converter, and particulate filter regeneration. This multi-functionality approach allows extended controlled segment coverage while avoiding proportional increases in control system complexity through unified control architecture.
4Reliability
If natural frequency control is used to utilize entire catalytic converter volume, then the conversion efficiency is improved, but the control precision requirements increase
Solution Approach 1:
The patent implements periodic lambda control oscillations at the natural frequency of the catalytic converter system. By using periodic action rather than continuous control, the system achieves efficient utilization of the entire catalytic converter volume while reducing measurement precision requirements through resonance-based control that amplifies effective conversion without requiring ultra-precise control inputs.
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 exhaust gas aftertreatment efficiency by optimizing lambda control based on component temperatures, ensuring optimal pollutant conversion and reducing emissions, while extending catalytic converter service life and avoiding hot spots, and allows for emission-neutral particulate filter regeneration.
Implementation Method 1
a first three-way catalytic converter (30) is arranged in the exhaust gas system and at least a second three-way catalytic converter (36) is arranged downstream from the first three-way catalytic converter (30)
Implementation Method 2
a first lambda probe (40) is arranged in the exhaust gas channel upstream from the first three-way catalytic converter (30), whereas another lambda probe (42) is arranged downstream from the first three-way catalytic converter (30) and upstream from the second three-way catalytic converter (36)
Implementation Method 3
it has been found that a lambda control concept with a rigidly configured control system only yields suboptimal emission results... do not sufficiently take into account the temperature-dependent conversion behavior of the catalytic converters
Data Source
AI summary
The invention relates to a method for exhaust gas aftertreatment in an internal combustion engine. For purposes of the exhaust gas aftertreatment in the internal combustion engine, an exhaust gas system is provided in which a first three-way catalytic converter is arranged, as seen in the direction in which the exhaust gas of the internal combustion engine flows through the exhaust gas system, while at least another three-way catalytic converter is arranged downstream from the first three-way catalytic converter. Here, at least one lambda probe is arranged in an exhaust gas channel of the exhaust gas system upstream from the appertaining three-way catalytic converters. In the proposed method, a component temperature of the three-way catalytic converters is determined and compared to a light-OFF temperature. In this process, the lambda control of the internal combustion engine is carried out by means of the lambda probe upstream from the last three-way catalytic converter that has reached its light-OFF temperature.Moreover, according to the invention, an exhaust gas aftertreatment system for carrying out such a method is being proposed.