Fuel Injector Needle Sleeve Dynamics for Injection Profile Control
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Solution Overview
Problem
Current fuel injectors for internal combustion engines lack flexibility in adjusting fuel injection rates and profiles, and they often suffer from hydraulic inefficiencies due to the design of intensifier systems.
Innovation Solution
A fuel injector design that includes a movable valve needle and needle sleeve, with independent control chambers and valves, allowing for simultaneous or sequential movement to alter injection rates and profiles by controlling pressure in the chambers, thereby enabling different lift states and injection rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single control chamber and valve design is used, then the device complexity is reduced, but the adaptability in adjusting fuel injection rates and profiles is limited
Solution Approach 1:
The control system is segmented into multiple independent control chambers (first control chamber and second control chamber) with separate control valves. This allows independent control of different aspects of fuel injection, enabling flexible adjustment of injection rates and profiles while maintaining manageable system complexity through modular design
Solution Approach 2:
The needle sleeve is made movable relative to the piston guide, creating a dynamic structure that can adjust its position based on control chamber pressure. This dynamic element enables variable injection rates and profiles by changing the effective orifice area during operation, providing adaptability without requiring multiple fixed geometric configurations
2Adaptability or versatility
If intensifier systems are used to generate injection rate flexibility, then adaptability is improved, but hydraulic inefficiencies increase
Solution Approach 1:
The patent extracts and eliminates the intensifier system from the fuel injection mechanism. Instead of using an intensifier piston to generate injection rate flexibility, the invention uses direct pressure control in separate control chambers acting on the needle sleeve, thereby removing the source of hydraulic inefficiencies while retaining injection rate adaptability
Solution Approach 2:
The invention uses hydraulic pressure control in the first and second control chambers to directly control the position of the valve needle and needle sleeve. By using controlled hydraulic pressure instead of mechanical intensifier systems, the patent achieves injection rate flexibility through fluid pressure management, improving hydraulic efficiency
3Adaptability or versatility
If fixed orifice geometry is used, then manufacturing precision is improved, but the ability to change injection rates is reduced
Solution Approach 1:
The needle sleeve is designed to move axially relative to the piston guide, creating a dynamic flow area that can be adjusted during operation. This movable component allows the effective orifice geometry to change without altering the physical nozzle holes, enabling variable injection rates while maintaining simple fixed nozzle geometry for manufacturing precision
Solution Approach 2:
The invention changes the operational parameters of the system by controlling pressure in the control chambers, which in turn changes the position of the needle sleeve and effectively changes the flow area. This parameter-based control (pressure control) allows injection rate variation without changing the physical geometry of the orifices, maintaining manufacturing simplicity
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 design provides increased flexibility in fuel injection rates and profiles, reducing hydraulic inefficiencies and allowing for precise control of injection events, including the ability to change rates at the beginning and end of injection events without altering orifice geometry.
Implementation Method 1
a first control chamber for controlling the position of the valve needle relative to the needle sleeve
Implementation Method 2
a second control chamber for controlling the position of the needle sleeve relative to the piston guide
Implementation Method 3
the fuel pressure in the injector nozzle 5 is higher than the fuel pressure in the control chamber 19 and a pressure force applied to the injector needle 7 overcomes the bias of the spring 15
Data Source
AI summary
The present invention relates to a fuel injector for use in delivering fuel to an internal combustion engine. The fuel injector includes a nozzle having a valve needle which is movable with respect to a valve needle seat. The valve needle travels through a range of movement between a closed position and an open position to control fuel delivery through at least one nozzle outlet. The valve needle cooperates with a needle sleeve or a control member which is located in a piston guide. The valve needle is movable relative to the needle sleeve or the control member. The needle sleeve or the control member is movable relative to the piston guide. The invention also relates to a method of operating a fuel injector; and a fuel injector control unit.