Fuel Injector Nozzle Variable Damping Control
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Solution Overview
Problem
Existing fuel injectors lack the ability to vary injection rates effectively, particularly at low initial rates, which limits their flexibility in reducing NOx formation during premixed combustion and maintaining combustion efficiency.
Innovation Solution
A nozzle assembly with a needle motion controller that transitions from a fixed damping fluid communication to an unrestricted fluid communication as the valve assembly lifts, allowing for variable damping forces and improved control over needle lift and injection rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a throttle orifice is sized to maintain pressure difference at maximum flow rate, then the needle can reach its final stop position, but the NMC has little effect on the initial rate of injection
Solution Approach 1:
The patent applies the Dynamics principle by making the fluid communication variable rather than fixed. The NMC transitions from a restricted flow state when closed to an unrestricted flow state when lifted, allowing the system to adapt the damping effect dynamically during the needle lift process. This resolves the contradiction by enabling both adequate pressure maintenance at maximum flow and effective control at initial injection rates through the variable communication area.
Solution Approach 2:
The patent applies the Parameter changes principle by changing the flow restriction parameter (communication area) as a function of needle lift position. The unrestricted fluid communication area increases with needle lift, transforming the fixed parameter approach of conventional throttles into a variable parameter system that can optimize performance across different injection phases.
2Force
If a single orifice is used for INO to set damping rate, then the needle lift rate can be controlled, but different levels of damping force cannot be applied at different needle lifts
Solution Approach 1:
The patent applies the Dynamics principle by transitioning from a static single orifice damping system to a dynamic variable communication system. The unrestricted fluid communication area varies with needle lift position, enabling the damping force to adapt automatically throughout the injection process rather than remaining constant as with a single orifice.
Solution Approach 2:
The patent applies the Segmentation principle by dividing the fluid communication into multiple pathways: a fixed damping fluid communication and an unrestricted fluid communication that activates at different needle lift stages. This segmentation allows different damping characteristics to be applied at different phases of needle motion.
3Productivity
If high injection rate is maintained during premixed combustion phase, then combustion efficiency is maintained, but NOx formation increases
Solution Approach 1:
The patent applies the Periodic action principle by implementing time-varying injection rates through the variable damping force. The injection rate is higher during the premixed combustion phase (when the needle is initially lifting) and can be reduced subsequently, creating a periodic injection pattern that optimizes combustion efficiency while controlling NOx formation through phased rate variation.
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 enables more precise control over injection rates, reducing NOx formation and maintaining combustion efficiency by varying the damping force during different stages of needle lift, thereby enhancing the performance of fuel injectors.
Implementation Method 1
a pressure difference between an upstream chamber and a downstream chamber of the nozzle
Implementation Method 2
The flow rate through the throttle orifice is continually increasing as the needle lifts
Implementation Method 3
a fixed damping fluid communication between said chambers
Data Source
Figure 1~3
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Figure 8
AI summary
A nozzle assembly (14) of a fuel injector (12) comprising a body (16) wherein is guided a valve assembly (18) comprising a needle member (20) and a needle motion controller, (NMC 22) cooperating with the inner face of said body (16). The NMC (22) is provided with a variable fluid communication between evolving from a restricted flow state, when the valve assembly (18) is in a closed position, to an unrestricted flow state when the valve assembly (18) is lifted away from said closed position.