Fuel Injector Spray Control via Variable Pressure Segmentation
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Solution Overview
Problem
Existing fuel injection techniques that divide an injection event into multiple portions with varying fuel flow rates increase fuel consumption and decrease engine efficiency while attempting to reduce NOx formation.
Innovation Solution
A fuel system with a variable pressure fuel supply and a fuel injector featuring two sets of needle valve elements and orifices, allowing for different pressure levels during an injection event to maintain a constant fuel flow rate, reducing NOx formation by controlling droplet size and combustion area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel flow rate is reduced during initial portion of injection event, then NOx formation is reduced, but total length of injection event increases which increases fuel consumption
Solution Approach 1:
The injection event is divided into two distinct portions: an initial portion with reduced fuel flow rate to control NOx formation, and a subsequent portion with unrestricted fuel flow rate to maintain engine efficiency. This segmentation allows the system to achieve both NOx reduction and fuel efficiency by optimizing fuel delivery at different stages of the injection event.
Solution Approach 2:
The fuel flow rate is dynamically adjusted during the injection event based on the specific requirements of each portion. The system transitions from a controlled, reduced flow rate during the initial portion to an unrestricted, higher flow rate during the subsequent portion, allowing optimal control of both NOx formation and fuel consumption at different times.
2Object-generated harmful factors
If fuel flow rate is reduced during initial portion of injection event, then NOx formation is reduced, but injection event length increases which decreases engine efficiency
Solution Approach 1:
The injection event is segmented into two portions with different fuel flow characteristics. The initial portion uses reduced flow rate to minimize NOx formation, while the subsequent portion uses unrestricted flow rate to maintain high engine efficiency, thereby resolving the contradiction between NOx reduction and engine efficiency.
Solution Approach 2:
The injection event employs periodic variation in fuel flow rate, transitioning from a controlled rate during the initial portion to an unrestricted rate during the subsequent portion. This periodic action allows the system to achieve both NOx reduction and maintained engine efficiency by optimizing fuel delivery at different temporal stages.
3Object-generated harmful factors
If variable pressure fuel supply is used with two sets of injector orifices, then fuel flow rate can be maintained constant while reducing NOx, but device complexity increases
Solution Approach 1:
The injector is segmented into two distinct sets of orifices: a first set for the initial portion of the injection event and a second set for the subsequent portion. Each set is controlled by its own needle valve element, allowing independent control of fuel flow rates to optimize NOx reduction while maintaining constant overall fuel flow rate.
Solution Approach 2:
Different portions of the injector have different local qualities - the first set of orifices is optimized for controlled, reduced flow rate to minimize NOx formation, while the second set is optimized for unrestricted flow rate to maintain engine efficiency. This local differentiation allows each region to perform its specific function optimally.
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 NOx production while maintaining engine efficiency by ensuring a constant fuel flow rate throughout the injection event, similar to conventional injectors, and effectively burning particulate matter with smaller droplets.
Implementation Method 1
A variable pressure fuel supply is configured to selectively supply fuel at different pressure levels to the injector cavity
Implementation Method 2
The first needle valve element is movable from a closed position against the first valve seat blocking flow through the first set of injector orifices to an open position permitting flow through the first set of injector orifices
Implementation Method 3
The plurality of injector orifices communicating with a first end of the injector cavity to discharge fuel into the combustion chamber
Data Source
AI summary
The disclosure provides an improved fuel injector and method of operating the fuel injector to provide at least two different types of fuel spray to a combustion chamber of an internal combustion engine. The two types of spray are formed by providing a first fuel pressure to the fuel injector during a first portion of an injection event at a first pressure and providing a second fuel pressure to the fuel injection during a second portion of the injection event, and maintaining a substantially constant fuel flow rate throughout the injection event.