Turbocharged Internal Combustion Engine EGR Fuel Injection for Exhaust Cooling
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Solution Overview
Problem
Current internal combustion engines face challenges in managing exhaust gas temperatures during high-load operations, leading to potential thermal damage of exhaust aftertreatment components due to stoichiometric combustion, which increases emissions and requires large, space-consuming coolers, while existing solutions like water injection and exhaust gas recirculation have drawbacks.
Innovation Solution
A method involving an internal combustion engine with an exhaust gas turbocharger and a low-pressure exhaust gas recirculation system, where fuel is injected into the recirculation system to adjust the combustion process, optimizing fuel evaporation and reducing residual oxygen content, thereby minimizing thermal stress on exhaust components and improving emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If stoichiometric combustion is used to ensure reliable exhaust aftertreatment, then emissions are reduced, but exhaust gas temperature rises sharply causing thermal damage to exhaust aftertreatment components
Solution Approach 1:
The fuel injection is segmented into two separate systems: direct injection into the combustion chamber and injection into the exhaust gas recirculation line. This segmentation allows the total fuel quantity to be distributed between two locations, enabling stoichiometric combustion while controlling exhaust temperature through the EGR fuel evaporation effect.
Solution Approach 2:
The exhaust gas recirculation system acts as an intermediary medium. Fuel injected into the EGR line evaporates and mixes with the recirculated exhaust gas, which then enters the combustion chamber. This intermediary process allows heat transfer and mixture preparation that reduces peak combustion temperatures and exhaust gas temperatures.
2Temperature
If exhaust gas cooler is used to reduce exhaust gas temperature, then thermal damage to exhaust aftertreatment components is avoided, but installation space and vehicle weight increase
Solution Approach 1:
The exhaust gas recirculation system provides self-cooling through the evaporation of fuel injected into the EGR line. The fuel acts as its own coolant, absorbing heat from the hot exhaust gas during evaporation and mixing, thereby reducing exhaust temperature without requiring an external exhaust gas cooler.
Solution Approach 2:
Fuel injected into the exhaust gas recirculation line undergoes phase transition from liquid to vapor. This evaporation process absorbs latent heat from the hot exhaust gas, effectively cooling the exhaust stream before it enters the aftertreatment components, eliminating the need for additional cooling hardware.
3Temperature
If water injection is used to reduce combustion and exhaust gas temperatures, then thermal damage is prevented, but additional injectors, water consumption, and system complexity increase
Solution Approach 1:
The existing exhaust gas recirculation system, already present for emissions control, is given an additional function by injecting fuel into it. This fuel injection into the EGR line serves dual purposes: controlling exhaust temperature and assisting in mixture preparation, eliminating the need for separate water injection hardware.
Solution Approach 2:
Instead of changing the substance injected (from water to fuel), the system utilizes the fuel already available in the vehicle's fuel system. By injecting fuel into the EGR line rather than water into the combustion chamber, the system achieves temperature control using existing infrastructure and materials.
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 allows for stoichiometric combustion without thermal damage, reduces emissions, and enhances combustion efficiency, particularly in direct-injection gasoline engines, by ensuring complete fuel utilization and homogeneous mixture formation.
Implementation Method 1
Fuel is injected into the low-pressure exhaust gas recirculation system and evaporates there
Implementation Method 2
The evaporation of the fuel injected into the low-pressure exhaust gas recirculation system cools the exhaust gas
Implementation Method 3
which comprises a turbine arranged in the exhaust system, which drives a compressor arranged in the intake tract
Implementation Method 4
At least one catalytic converter with a three-way function is arranged downstream of the turbine in the exhaust system
Data Source
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AI summary
The invention relates to a method for operating an internal combustion engine (10) charged by means of an exhaust turbocharger (80), said internal combustion engine having at least one combustion chamber (12), which is connected on the inlet side to an intake manifold (20) and is connected on the outlet side to an exhaust system (40). At least one ignition source, in particular a spark plug (14), is arranged on each combustion chamber (12) to ignite a combustion air mixture in the respective combustion chamber (12). A three-way catalytic converter (50) or a four-way catalytic converter (52) is arranged in the exhaust system (40). Furthermore, a sensor (56, 76) for detecting the oxygen concentration in the exhaust of the internal combustion engine (10) is arranged in the exhaust system (40). The exhaust system (40) is connected to the intake manifold (20) of the internal combustion engine (10) via a low pressure exhaust return (60), wherein a fuel injector (74) is arranged in the exhaust return (60). The method according to the invention comprises the following steps: - Determining a residual oxygen content (λ1) in the exhaust flow of the internal combustion engine (10) upstream of the catalytic converter (50, 52), - determining a load requirement (P) on the internal combustion engine (10), - injecting fuel into the low pressure exhaust return (60) if the residual oxygen content (λ1) in the exhaust flow of the internal combustion engine (10) is above a threshold value (λS) and/or the load requirement (P) exceeds a threshold value (PS), which allows for an incomplete conversion of the fuel injected into the combustion chambers (12) to be expected.