Gaseous Fuel Injection Near Ignition for Cold-Start Emissions
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Solution Overview
Problem
During engine cold-starts, hydrocarbons (HCs) are generated due to incomplete evaporation of fuel spray droplets, leading to fuel film accumulation on piston and cylinder liner, which results in inefficient combustion and increased tailpipe emissions.
Innovation Solution
Operating a reformer to generate gaseous fuel, which is then injected through an injector directly adjacent to an ignition device in a prechamber, creating a fuel-rich cloud proximal to the ignition device, enhancing combustion conditions. This involves injecting the gaseous fuel within a specific crank angle of the top-dead center of the compression stroke, typically when the spark is active, to improve combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid fuel is injected during cold-start, then fuel delivery is achieved, but spray droplets do not evaporate completely leading to fuel film accumulation and increased HC emissions
Solution Approach 1:
The patent changes the physical state parameter of the fuel from liquid to gas by using a vaporizer component. The vaporizer heats and evaporates liquid fuel to produce gaseous fuel that is then injected into the combustion chamber. This parameter change ensures complete vaporization and eliminates fuel film accumulation on piston and cylinder liner surfaces, thereby reducing hydrocarbon emissions during cold-start conditions.
Solution Approach 2:
The patent utilizes the phase transition from liquid to gas through the vaporizer component. The vaporizer transforms liquid fuel into gaseous fuel before injection, ensuring that the fuel is in a vapor state that can mix thoroughly with air and combust completely. This phase transition resolves the evaporation problem during cold-start by pre-evaporating the fuel outside the combustion chamber.
2Productivity
If spray penetration is increased to deliver fuel, then fuel delivery is improved, but fuel film accumulation on piston and cylinder liner increases
Solution Approach 1:
The patent changes the fuel state from liquid to gas, which fundamentally alters the fuel delivery mechanism. Gaseous fuel can be delivered effectively without requiring deep spray penetration, as it mixes with air through diffusion and convection rather than relying on liquid spray atomization. This eliminates the trade-off between delivery efficiency and fuel film accumulation.
Solution Approach 2:
The patent uses a vaporizer system that employs thermal energy and gas flow dynamics to deliver fuel. The gaseous fuel is introduced into the combustion chamber where it mixes with air currents, utilizing pneumatic principles rather than liquid spray mechanics. This approach achieves effective fuel delivery without the spray penetration issues that cause fuel film accumulation.
3Object-generated harmful factors
If combustion efficiency is improved during cold-start, then emissions are reduced, but additional components and system complexity are required
Solution Approach 1:
The patent segments the fuel delivery system into distinct functional components: a vaporizer unit separate from the main injection system, and a dedicated gaseous fuel injection pathway. This segmentation allows the vaporizer to handle the complex task of fuel evaporation independently, while the injection system focuses on delivering the vaporized fuel. The segmentation improves emissions reduction while managing complexity through functional separation.
Solution Approach 2:
The patent introduces a vaporizer as an intermediary component between the liquid fuel source and the combustion chamber. This intermediary performs the complex evaporation function, transforming liquid fuel into gas before injection. By placing this intermediary component in the fuel path, the system achieves complete fuel vaporization and reduced emissions without requiring complex injection timing and pressure control during cold-start.
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 method reduces fuel film formation and enhances combustion during cold-starts, thereby decreasing unburned hydrocarbon emissions and improving engine performance in meeting stringent emissions regulations.
Implementation Method 1
Operating a reformer to generate a gaseous fuel
Implementation Method 2
injecting the gaseous fuel through an injector directly adjacent to an ignition device arranged in a prechamber
Implementation Method 3
enhancing combustion conditions
Data Source
AI summary
Methods and systems are provided for injecting gaseous fuel during an engine start. In one example, a method comprises generating gaseous fuel via a fuel gasification device and injecting the gaseous fuel via a fuel injector. The fuel injector is configured to inject adjacent to an ignition device.