Pilot Fuel Injection Geometry for Stable Gaseous-Fuel Ignition
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Solution Overview
Problem
Existing techniques lack effective methods for injecting a pilot fuel into internal combustion engines to ignite gaseous fuels, particularly for engines using high-pressure gaseous fuels with low cetane numbers, leading to inefficiencies and high diesel-fuel substitution factors.
Innovation Solution
The method involves reducing the quantity and carbon content of pilot fuel through techniques such as altering the geometry of injection holes, using alternative fuels, and employing advanced actuation mechanisms to achieve stable ignition of gaseous fuels with reduced pilot fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pilot fuel injection techniques are used to ignite gaseous fuel, then reliable ignition is achieved, but high quantities of pilot fuel are consumed resulting in high diesel-fuel substitution factors
Solution Approach 1:
The patent applies parameter changes by modifying the injection hole geometry parameters (diameter, length, number of holes) and pilot fuel injection parameters (pressure, timing, duration) to optimize the balance between ignition reliability and pilot fuel consumption. By carefully adjusting these parameters, the system achieves stable ignition with significantly reduced pilot fuel quantities compared to conventional techniques.
Solution Approach 2:
The patent employs local quality by creating multiple injection holes with different geometries positioned at specific locations within the combustion chamber. Each injection hole is designed with specific diameter, length, and angular orientation to deliver pilot fuel to optimal ignition zones, ensuring reliable ignition while minimizing overall pilot fuel consumption through localized optimization.
2Reliability
If diesel fuel is used as pilot fuel to ignite gaseous fuel, then auto-ignition is achieved, but carbon emissions increase
Solution Approach 1:
The patent reduces carbon emissions by changing the chemical composition parameters of the pilot fuel. Instead of using pure diesel fuel, the system employs alternative pilot fuels with lower carbon content such as synthetic fuels, alcohol-based fuels, or diluted fuel mixtures. This parameter change maintains the auto-ignition capability while significantly reducing carbon emissions during the ignition process.
Solution Approach 2:
The patent treats the pilot fuel as a consumable resource that is intentionally minimized and disposed of after serving its ignition function. By using low-cost alternative fuels with lower carbon content and optimizing the injection parameters to achieve ignition with minimal fuel quantity, the system reduces the environmental impact of the disposable pilot fuel component.
3Quantity of substance
If injection hole diameter is reduced to lower pilot fuel flow, then pilot fuel consumption decreases, but injection pressure requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the single injection hole into multiple smaller injection holes. This segmentation allows the system to achieve the desired total pilot fuel flow rate through multiple openings rather than requiring a single large hole. The multiple smaller holes collectively provide sufficient fuel delivery while maintaining lower individual hole diameters that reduce the pressure differential requirements and prevent clogging.
Solution Approach 2:
The patent transitions from a single-dimension approach (single hole diameter) to a multi-dimensional optimization approach by simultaneously varying the number of holes, their individual diameters, their lengths, and their angular orientations. This dimensional expansion allows the system to achieve optimal pilot fuel delivery by distributing the flow across multiple spatial dimensions rather than relying on a single large opening.
4Reliability
If pilot fuel injection timing is advanced to improve ignition stability, then combustion reliability improves, but gaseous fuel injection timing flexibility is reduced
Solution Approach 1:
The patent segments the fuel injection process into distinct pilot fuel injection and gaseous fuel injection phases with independent timing control. By using separate injection systems or sequential injection modes, the system can optimize the pilot fuel injection timing for maximum ignition stability while maintaining independent flexibility in gaseous fuel injection timing. This segmentation allows each fuel type to be injected at its optimal moment without compromising the other.
Solution Approach 2:
The patent employs dynamic timing control where the injection timing parameters are adjustable based on operating conditions. The system can dynamically optimize pilot fuel injection timing for ignition stability while maintaining the ability to adapt gaseous fuel injection timing to various engine loads and operating modes. This dynamic approach allows the system to achieve both reliable ignition and operational flexibility across different conditions.
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 maintains good ignition stability with significantly lower pilot fuel quantities, reducing emissions and operational costs while allowing for efficient operation across various engine conditions.
Implementation Method 1
The pilot fuel can be injected later in the compression stroke into a pressure and temperature environment that causes the pilot fuel to auto-ignite and combust thereby creating another pressure and temperature environment suitable for igniting the gaseous fuel
Implementation Method 2
the injection pressure of the gaseous fuel needs to be greater than the pressure in the combustion chamber (also known as in-cylinder pressure) at the time of injection
Data Source
AI summary
An apparatus and method for injection of a pilot fuel into an internal combustion engine includes a variety of steady state, transient and other techniques to reduce an injection quantity of the pilot fuel and/or a carbon content of the pilot fuel.