Manifold Fuel Injection for Intake Charge Cooling and NOx Reduction
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Solution Overview
Problem
Existing NOx reduction methods in internal combustion engines face challenges such as combustion instability due to water injection, dependence on available water, ineffective NOx capture during cold-start conditions, and adverse effects on fuel economy due to catalyst saturation and deceleration fuel shut-off events.
Innovation Solution
Adjusting the fuel injection schedule by varying the proportion of fuel delivered via manifold injection relative to port and direct injection based on estimated oxygen content in the exhaust catalyst and engine operating conditions to reduce NOx production, particularly during cold-start and deceleration fuel shut-off events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If water is injected into engine cylinders to reduce combustion temperature and NOx emissions, then NOx production is reduced, but combustion stability deteriorates and the system becomes dependent on available water
Solution Approach 1:
The patent extracts the water injection function from the combustion chamber and relocates it to the intake manifold. By injecting water into the intake manifold instead of directly into the cylinder, the system achieves charge cooling and NOx reduction while avoiding direct interference with the combustion process, thereby maintaining combustion stability.
Solution Approach 2:
The intake manifold serves as an intermediary between the water injection system and the combustion chamber. Water is injected into the intake manifold where it evaporates and cools the charge before entering the cylinder, indirectly achieving NOx reduction without directly disrupting combustion.
2Object-generated harmful factors
If fuel is injected via central fuel injection into the intake manifold to cool the charge and reduce NOx, then NOx production is reduced, but the system complexity increases
Solution Approach 1:
The central fuel injection system performs multiple functions: it delivers fuel to the engine and simultaneously cools the intake charge. By using the existing fuel injection infrastructure for dual purposes, the system achieves NOx reduction without adding separate water injection hardware, thereby limiting complexity increase.
Solution Approach 2:
The fuel system serves itself by using the injected fuel not only for combustion but also as a cooling medium. The evaporation of injected fuel in the intake manifold provides charge cooling and NOx reduction, eliminating the need for separate cooling systems.
3Use of energy by moving object
If the exhaust catalyst is saturated with oxygen during deceleration fuel shut-off, then fuel economy is improved, but NOx adsorption capacity is reduced until catalyst purging is required
Solution Approach 1:
The system performs preliminary cooling of the intake charge during deceleration fuel shut-off events. By reducing NOx production at the source through charge cooling, the system prepares for subsequent catalyst regeneration without requiring extensive purging operations, thereby maintaining both fuel economy and NOx capture effectiveness.
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 effectively reduces NOx emissions by optimizing charge cooling and catalyst desorption, improving emissions quality and fuel efficiency without relying on variable water sources.
Implementation Method 1
When fuel is injected into the engine intake, heat is transferred from the intake air and/or engine components to the fuel and this heat transfer leads to atomization of a portion of the fuel, which results in cooling of the engine components
Implementation Method 2
heat is transferred from the intake air and/or engine components to the fuel and this heat transfer leads to atomization of a portion of the fuel
Implementation Method 3
After the exhaust catalyst has attained the light-off temperature is the exhaust catalyst able to adsorb oxidants such as NOx and oxygen passing there-through
Implementation Method 4
Internal combustion engines may include central fuel injection (CFI) systems that inject fuel into an intake manifold
Data Source
AI summary
Methods and systems are provided for adjusting engine operating conditions for reduction of NOx emissions. In one example, immediately after a fuel shut-off event, in response to an oxygen content of an exhaust catalyst being higher than a threshold, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection. By increasing manifold cooling, NOx production may be reduced.