Fuel Injector Control Valves for Needle Velocity and Leak Reduction
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Solution Overview
Problem
Existing fuel injector systems for internal combustion 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 lead 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 high and low rates, and reducing static leaks by using different cross-sectional areas for restricted pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single nozzle control valve is used to control fuel pressure in the control chamber, then the structure is simple, but the ability to provide multiple injection rates and control needle opening velocity is limited
Solution Approach 1:
The single nozzle control valve is divided into two separate valves: a first nozzle control valve for controlling fuel pressure to establish needle opening velocity, and a second nozzle control valve for controlling fuel pressure to maintain injection rate. This segmentation allows independent control of different injection phases without increasing overall system complexity.
Solution Approach 2:
Each nozzle control valve is designed with multi-functionality, capable of operating in different modes (e.g., as a fill valve or drain valve) depending on the injection requirement. The first nozzle control valve can function as both a fill valve and a drain valve, while the second nozzle control valve primarily functions as a drain valve, providing versatile control capabilities.
2Speed
If the flow rates of control orifices are adjusted to control needle opening velocity, then needle opening velocity can be controlled, but needle closing rate or minimum injection pressure may be detrimentally influenced
Solution Approach 1:
The control of needle opening and closing is segmented into separate functions handled by different valves. The first nozzle control valve independently controls needle opening velocity through its restricted pathways, while the second nozzle control valve independently controls needle closing by providing a separate drain path. This segmentation eliminates the trade-off between opening velocity and closing rate.
3Productivity
If an amplifier piston is used to provide high injection rates, then high injection rates can be achieved, but the system becomes inefficient, large and expensive
Solution Approach 1:
The amplifier piston mechanism is extracted and replaced with a simpler two-valve control system. Instead of using a large amplifier piston to achieve high injection rates, the invention uses the first and second nozzle control valves with appropriately sized restricted pathways to control fuel flow, eliminating the need for complex amplification mechanisms while maintaining high injection rate capability.
4Adaptability or versatility
If two valves are used for controlling fuel pressure in the control chamber, then multiple injection rates can be provided, but static leaks may increase
Solution Approach 1:
Each nozzle control valve is designed with specific local qualities - the first nozzle control valve has restricted pathways optimized for its fill/drain function, while the second nozzle control valve has restricted pathways optimized for its drain function. This localized optimization ensures that each valve contributes minimally to static leaks while maintaining its specific control 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
This solution provides improved control over needle movement, enabling efficient 'square' injection rates for high spray energy and precise quantity control, while minimizing complexity and static leaks, thus optimizing diesel engine combustion performance.
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
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
Data Source
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AI summary
The present invention relates to a fuel injector (1) for use in delivering fuel to an internal combustion engine. The fuel injector (1) 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 (18). The injector (1) has first and second nozzle control valves (8, 10) for controlling fuel flow into and out of the control chamber (18) to pressurise and depressurise the control chamber, respectively. The first nozzle control valve (10) can operate selectively to place the control chamber (18) in fluid communication with a fuel drain (28). The first nozzle control valve (8) can also operate selectively to place the control chamber (18) in fluid communication with a high pressure supply line (26). The second nozzle control valve (10) can operate selectively to place the control chamber (18) in fluid communication with a fuel drain (30). In an alternate arrangement, a filling valve (80) can be provided selectively to place a high pressure supply line (24) in fluid communication with the control chamber (18). The present invention also relates to a method of operating a fuel injector (1); and a fuel injector control system.