Central Fuel Injection for Pre-Ignition Mitigation
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Solution Overview
Problem
Existing engine technologies face challenges in mitigating pre-ignition events in high compression ratio engines, leading to increased particulate matter emissions and fuel consumption due to direct injection methods, which can result in engine component damage and inefficient fuel use.
Innovation Solution
Implementing a method that selectively increases fuel delivery via central fuel injection (CFI) relative to port and direct injection, maintaining a stoichiometric air-fuel ratio, to leverage manifold charge cooling and reduce the need for cylinder enrichment, thereby mitigating pre-ignition without increasing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct injection is used to cool the charge and mitigate pre-ignition, then pre-ignition is reduced, but particulate matter emissions increase due to insufficient fuel-air mixing
Solution Approach 1:
The fuel injection system is segmented into multiple injection locations: central fuel injection into the intake manifold and port/direct injection into cylinders. This segmentation allows the central injection to provide charge cooling without the harmful effects of direct cylinder injection, while port/direct injection maintains proper fuel-air mixing for combustion
Solution Approach 2:
The intake manifold serves as an intermediary medium where central fuel injection occurs. Fuel injected into the manifold cools the charge through evaporation before air-fuel mixture enters cylinders, avoiding direct injection into cylinders that causes poor mixing and soot formation
2Reliability
If cylinder enrichment is used to mitigate pre-ignition, then pre-ignition is reduced, but fuel consumption increases
Solution Approach 1:
Charge cooling is applied locally at the intake manifold level rather than requiring enrichment of individual cylinders. The central fuel injection cools the incoming charge for all cylinders uniformly, providing pre-ignition mitigation without the fuel penalty of cylinder-by-cylinder enrichment
3Reliability
If multiple cylinders are enriched concurrently to address pre-ignition, then pre-ignition is mitigated, but fuel consumption increases significantly
Solution Approach 1:
Central fuel injection into the intake manifold provides a universal cooling effect for all cylinders simultaneously. A single injection point serves multiple cylinders, providing pre-ignition mitigation across the engine without the cumulative fuel consumption of enriching multiple cylinders individually
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 the propensity for pre-ignition, improves fuel efficiency, and decreases particulate matter emissions by utilizing charge cooling effects across all cylinders, minimizing the need for enrichment and associated fuel consumption.
Implementation Method 1
When fuel is injected into the engine intake, heat is transferred from the intake air and/or local engine components to the fuel and this heat transfer leads to atomization of a portion of the fuel, which results in cooling of the manifold, and thereby cooling of the manifold air charge
Implementation Method 2
heat is transferred from the intake air and/or local engine components to the fuel
Data Source
AI summary
Methods and systems are provided for adjusting engine operating conditions for mitigation of pre-ignition in one or more engine cylinder. In one example, a method may include, in response to indication of pre-ignition, 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, while maintaining engine operation at or around a stoichiometric air-fuel ratio.