Split Check Assembly Trapped Volume Fuel Injector
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Solution Overview
Problem
Existing pressurized fuel systems face limitations in achieving optimal performance, particularly at lower engine loads, due to inherent hardware constraints that affect precise fuel injection and emission control, especially in reducing NOx and particulate matter emissions.
Innovation Solution
The fuel injector incorporates a split check assembly with a trapped volume and starting rate shape clearance, which allows for hydraulic coupling of control and outlet pieces to modulate fuel injection rate shape by leaking fuel through a clearance, enabling precise control over fuel injection rates and improving minimum delivery capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single-piece check assembly is used, then the device complexity is low, but the manufacturing precision and control precision of fuel injection rate are insufficient
Solution Approach 1:
The check assembly is divided into multiple separate pieces (control piece, outlet piece, check piece) that can move independently relative to each other. This segmentation allows each piece to be precisely manufactured and positioned, enabling accurate control of fuel injection rate by independently controlling the movement and clearance of each component.
2Adaptability or versatility
If the check assembly components are tightly coupled, then the response speed is fast, but the ability to modulate fuel injection rate shape is limited
Solution Approach 1:
A trapped volume is introduced as an intermediary hydraulic coupling between the control piece and outlet piece. This trapped volume allows the control piece to hydraulically actuate the outlet piece with controlled delay and modulation. The starting rate shape clearance further mediates the hydraulic flow, enabling precise shaping of the fuel injection rate while maintaining responsive actuation through the trapped volume's hydraulic coupling.
3Object-generated harmful factors
If fuel injection quantity is reduced for lower engine loads, then the emission control is improved, but the precision of fuel injection delivery deteriorates
Solution Approach 1:
The invention implements different clearance characteristics at different stages of the injection process. The starting rate shape clearance provides controlled leakage during the initial phase to enable precise minimum delivery, while the subsequent injection phase achieves higher rates through the full opening of the check assembly. This local differentiation of clearance properties allows precise control across the entire injection range from minimum to maximum delivery.
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 enhances the precision and efficiency of fuel injection, particularly at lower engine loads, by allowing for a gradual and accelerating fuel injection rate, improving emission control and system performance compared to traditional designs.
Implementation Method 1
A trapped volume is formed between the control piece and the outlet piece, within the check sleeve, and hydraulically couples the control piece to the outlet piece
Implementation Method 2
A starting rate shape clearance fluidly connects the trapped volume to the fuel cavity and is formed between the check sleeve and the at least one of the control piece or the outlet piece received therein
Data Source
AI summary
A fuel system includes a fuel injector having a split check assembly with a control piece, an outlet piece, and a check sleeve. A trapped volume is formed between the control piece and the outlet piece within the check sleeve, to hydraulically couple the control piece to the outlet piece. A starting rate shape clearance fluidly connects the trapped volume to a fuel cavity and is formed between the check sleeve and one of the control piece or outlet piece received therein, and modulates a starting rate shape of fuel injection from the fuel injector. Related methodology is disclosed.