Actively Heated Catalyst Lambda Control for Exhaust Aftertreatment
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Solution Overview
Problem
Existing exhaust gas aftertreatment systems face challenges in efficiently controlling and optimizing the performance of multiple catalysts in multi-stage exhaust gas aftertreatment systems, particularly in achieving optimal pollutant conversion under varying operating conditions, as traditional lambda control methods deliver suboptimal emission results.
Innovation Solution
The system employs a method with multiple lambda sensors and actively heatable three-way catalysts, where lambda control is adjusted based on catalyst light-off temperatures and load conditions, ensuring efficient pollutant conversion by optimizing the catalytically effective volume and extending lambda control to downstream sensors as catalysts reach operational temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a multi-stage exhaust aftertreatment system is used, then pollutant conversion efficiency is improved, but control complexity and system complexity increase
Solution Approach 1:
The exhaust aftertreatment system is divided into multiple catalyst stages (first catalytic converter, second catalytic converter, third catalytic converter) positioned at different locations in the exhaust system. Each catalyst stage can be independently controlled and monitored by dedicated lambda sensors, allowing segmented control of pollutant conversion processes while managing overall system complexity through modular architecture
Solution Approach 2:
The lambda control system dynamically adapts its behavior based on the thermal state of each catalyst stage. When a catalyst reaches its light-off temperature, the lambda control is extended to include downstream lambda sensors, creating a dynamic control structure that adjusts to operating conditions rather than maintaining a fixed complex control architecture
2Object-generated harmful factors
If lambda control is extended to downstream lambda sensors, then conversion performance is improved, but energy consumption increases due to active heating requirements
Solution Approach 1:
The second catalytic converter is pre-heated using an electric heating element before exhaust gas flow reaches it. This preliminary heating action ensures the catalyst reaches its light-off temperature and becomes operational before needing to process exhaust gases, enabling earlier extension of lambda control to downstream sensors without continuous energy input
Solution Approach 2:
The electric heating element operates periodically or temporarily to bring the second catalytic converter up to temperature, rather than maintaining continuous heating. Once the catalyst reaches operational temperature, the heating can be reduced or stopped, creating a periodic heating pattern that achieves the desired performance while limiting energy consumption
3Object-generated harmful factors
If multiple catalysts are used in series, then pollutant conversion is improved, but the system response time during cold start increases
Solution Approach 1:
The second catalytic converter is pre-heated by an electric heating element before cold start conditions fully develop. This preliminary heating action reduces the time required for the catalyst to reach its light-off temperature during cold start, enabling faster extension of lambda control to downstream sensors and improving overall system response time
Solution Approach 2:
The electric heating element acts as an intermediary device that accelerates the heating process of the second catalytic converter during cold start. This intermediary heating mechanism bridges the time gap between engine startup and catalyst activation, enabling faster pollutant conversion capability without requiring the entire multi-stage system to warm up sequentially
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 the conversion performance of exhaust gas aftertreatment systems, minimizing tailpipe emissions by optimizing catalyst usage and maintaining efficient pollutant conversion across varying load profiles and catalyst aging, while reducing energy consumption and extending catalyst life.
Implementation Method 1
The second catalyst (36) is designed as a three-way catalyst that can be actively heated electrically by means of an electrical heating element (52)
Implementation Method 2
a first lambda probe (38) upstream of the first catalyst and a second lambda probe (40) downstream of the first catalyst and upstream of the second catalyst, with a third lambda probe (42) downstream of the second catalyst
Implementation Method 3
The first catalyst (28) and the third catalyst (32) are designed as three-way catalysts. The second catalyst (30) is designed as a three-way catalyst that can be actively heated
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for the exhaust aftertreatment of an internal combustion engine (10) with an exhaust system (20) in which at least three catalysts (28, 30, 32, 34) and at least three lambda sensors (38, 40, 42) are arranged. An actively heated catalyst (36) is provided downstream of a first catalyst (28), which is actively heated from the moment the internal combustion engine (10) is started. The lambda control of the internal combustion engine (10) is carried out by the lambda sensor (38, 40, 42) downstream of the last catalyst (28, 30, 32, 34) that has reached its light-off temperature. The invention further relates to an exhaust aftertreatment system for carrying out such a method.