Fuel Injector Control Valves for Needle Velocity
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Solution Overview
Problem
Existing fuel injector systems for diesel engines face challenges in achieving precise control over fuel delivery, particularly in balancing high pressure energy conversion to spray energy and accurate quantity control, often requiring compromises that affect needle opening velocity and injection rates, leading to inefficiencies and increased complexity.
Innovation Solution
A fuel injector system with first and second nozzle control valves that allow for independent operation to control fuel flow into and out of a control chamber, enabling flexible needle opening velocities for various injection modes, including 'square' injection rates and slower mixing rates, while minimizing static leaks and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the flow rates of the control orifices are adjusted to control needle opening velocity, then needle opening velocity is improved, but needle closing rate or minimum injection pressure deteriorates
Solution Approach 1:
The single control orifice is segmented into multiple control orifices (first control orifice and second control orifice) with different flow characteristics. The first control orifice is optimized for needle opening velocity while the second control orifice is optimized for needle closing rate and minimum injection pressure. This segmentation allows each orifice to be independently optimized for its specific function, resolving the contradiction between needle opening velocity and needle closing rate/minimum injection pressure.
2Productivity
If an amplifier piston is used to provide high injection rates, then injection rate is improved, but system size and complexity deteriorates
Solution Approach 1:
The control orifices are designed to serve multiple functions: they control both needle opening velocity and needle closing rate, and they regulate both high pressure energy conversion and spray energy delivery. By making the control orifices multi-functional, the system achieves high injection rates and precise control without requiring separate dedicated components for each function, thereby reducing overall system complexity.
3Manufacturing precision
If control orifices are adjusted for specific injection events, then injection precision is improved, but system adaptability deteriorates
Solution Approach 1:
The system dynamically switches between different control orifices based on the injection event requirements. The control system can selectively activate the first control orifice for high velocity needle opening during certain injection events, and the second control orifice for precise needle closing and minimum pressure control during other events. This dynamic switching capability allows the system to adapt to different injection requirements while maintaining precision for each specific function.
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
The system provides improved control over needle opening velocity, enabling high spray energy efficiency and accurate quantity control, reducing spray over-penetration and enhancing hydraulic efficiency across different combustion modes and applications.
Implementation Method 1
first and second nozzle control valves for controlling fuel flow into and out of the control chamber to pressurise and depressurise the control chamber
Implementation Method 2
first nozzle control valve is operable selectively to place the control chamber in fluid communication with a fuel drain; said first nozzle control valve also being operable selectively to place the control chamber in fluid communication with a high pressure supply line
Implementation Method 3
a nozzle having a valve needle which is moveable with respect to a valve needle seating through a range of movement between a closed position and an open position to control fuel delivery through at least one nozzle outlet, whereby movement of the nozzle needle is controlled by fuel pressure within a control chamber
Data Source
AI summary
A fuel injector includes a nozzle having at least one nozzle outlet. A valve needle is moveable with respect to a valve needle seating through a range of movement between a closed position and an open position to control fuel delivery through the at least one nozzle outlet. The movement of the nozzle needle is controlled by fuel pressure within a control chamber. The injector has first and second nozzle control valves for controlling fuel flow into and out of the control chamber to pressurise and depressurise the control chamber, respectively. The first nozzle control valve can operate selectively to place the control chamber in fluid communication with a fuel drain or to place the control chamber in fluid communication with a high pressure supply line. The second nozzle control valve can operate selectively to place the control chamber in fluid communication with a fuel drain.