Lambda Split Internal Combustion Engine Exhaust Temperature Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing internal combustion engines face limitations in power density due to maximum exhaust gas temperature constraints imposed by catalytic converters and turbochargers, leading to increased fuel consumption and NOx emissions, especially with lean-burn operations.
Innovation Solution
Implementing a lambda split strategy where individual cylinders operate at different air-fuel ratios (rich and lean) with cylinder-specific ignition angles, combined with a manifold integrated into the cylinder head, to reduce exhaust gas temperatures without compromising emissions, and using a twin-scroll turbocharger to minimize temperature gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the internal combustion engine is operated with a lean air/fuel mixture to reduce fuel consumption, then fuel efficiency is improved, but exhaust gas temperature increases causing NOx breakthrough and catalyst damage
Solution Approach 1:
The exhaust system is segmented into multiple channels (first and second exhaust channels) that separately convey exhaust gases from different cylinders. This allows selective mixing of hot and cold exhaust streams to control temperature independently in different zones, enabling lean operation while protecting temperature-sensitive components.
Solution Approach 2:
A lambda probe is introduced as an intermediary sensing element in the first exhaust channel to detect exhaust composition and provide feedback for controlling the air-fuel mixture. This enables precise management of the lean burn operation to maintain optimal exhaust temperature and composition.
2Power
If the maximum exhaust gas temperature is increased to improve power density, then power output is improved, but the catalytic converter and turbocharger are damaged due to excessive temperature
Solution Approach 1:
The exhaust system is divided into separate channels that allow different temperature zones. High-temperature exhaust from power-producing cylinders can be separated from temperature-sensitive components, enabling higher power density without exceeding maximum permissible temperatures for the catalytic converter and turbocharger.
Solution Approach 2:
Different regions of the exhaust system are given different thermal characteristics. The first and second exhaust channels can have different temperature levels, allowing local optimization where power generation requires high temperature while component protection requires temperature control in specific zones.
3Temperature
If a cooled exhaust manifold is used to reduce exhaust gas temperature, then component protection is improved, but the power density is reduced due to lower exhaust gas temperature
Solution Approach 1:
Instead of uniformly cooling the entire exhaust manifold, the system segments the exhaust flow into separate channels. This allows selective cooling only where necessary (e.g., near the catalytic converter) while maintaining high exhaust gas temperatures in regions that contribute to power density, thus avoiding the trade-off present in conventional cooled manifolds.
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 reduces exhaust gas temperatures by up to 60°C, enhances power density, and improves combustion efficiency, while maintaining stoichiometric conditions for effective pollutant conversion in the exhaust gas purification system.
Implementation Method 1
the exhaust gas from the internal combustion engine first flows through a nitrogen oxide storage catalyst and then through an SCR catalyst
Implementation Method 2
the turbine draws enthalpy from the exhaust mass flow to compress the charge air via the compressor
Implementation Method 3
The internal combustion engine is operated with a lean air/fuel mixture (λ > 1) if the operating state of the internal combustion engine produces an exhaust gas temperature above a certain temperature
Data Source
Figure 1
Figure 2
AI summary
Applied-ignition internal combustion engine with at least one first combustion chamber and one second combustion chamber, in which a fuel/air mixture can be burned, wherein an exhaust gas system is arranged at the combustion chambers, and wherein an exhaust gas from a combustion of the fuel/air mixture first of all flows through an exhaust gas manifold and subsequently flows through an exhaust gas purification system in the exhaust gas system, wherein a first section of the exhaust gas system from the first combustion chamber to the exhaust gas purification system is better cooled than a second section of the exhaust gas system from the second combustion chamber to the exhaust gas purification system, and wherein the first combustion chamber can be operated with a lean (λ > 1) fuel/air mixture and the second combustion chamber can be operated with a rich (λ < 1) fuel/air mixture, wherein an overall exhaust gas lambda value at the inlet into the exhaust gas purification system is stoichiometric (λ = 1). By way of the method according to the invention, the exhaust gas temperatures can be lowered in an advantageous way for component protection and for performance increase.