High-Pressure Containment Sleeve for Fuel Injector Nozzle
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fuel injectors face structural limitations in sustaining pressures above 200 MPa due to geometrical constraints, leading to potential stress fractures and leakage issues in smaller designs, which existing nozzle assemblies with heart-shaped cavities cannot effectively address.
Innovation Solution
A high-pressure containment sleeve with adequate wall thickness and annular sealing lands is introduced to define the nozzle chamber, replacing traditional heart-shaped cavities, ensuring the sleeve remains out of contact with the needle valve member and enhancing sealing capabilities to maintain pressure without stress fractures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a heart shaped cavity is used in the nozzle assembly, then the structural design is simple, but the fuel injector cannot sustain pressures above 200 MPa due to stress fractures
Solution Approach 1:
The nozzle assembly is divided into separate functional components: a containment sleeve that defines the high-pressure chamber, a tip component with nozzle outlet, and a needle valve member. This segmentation allows each component to be optimized for its specific function, with the containment sleeve specifically designed to withstand high pressures through adequate wall thickness without the stress concentration issues of integrated heart-shaped cavities
Solution Approach 2:
A containment sleeve is introduced as an intermediary component between the high-pressure fuel chamber and the needle valve assembly. This sleeve acts as a pressure-containing structure that isolates the high-pressure zone, allowing the needle valve to operate without being directly subjected to the full pressure loads that would cause stress fractures in traditional integrated designs
2Strength
If the wall thickness of the containment sleeve is increased to prevent stress fractures, then pressure sustainability improves, but the injector size increases
Solution Approach 1:
The containment sleeve is designed with locally optimized wall thickness that provides adequate strength only where high pressure containment is required, rather than uniformly thick walls throughout the entire injector. The sleeve walls are thick enough to prevent stress fractures at critical high-pressure zones while maintaining overall compact dimensions of the injector
3Manufacturing precision
If the needle valve member is in contact with the containment sleeve for guidance, then alignment accuracy improves, but sealing effectiveness decreases due to potential leakage paths
Solution Approach 1:
A separate tip component serves as an intermediary that provides both the nozzle outlet structure and the needle guidance function. The needle valve member is guided by the tip component rather than directly by the containment sleeve, creating a distinct sealing interface between the needle and tip component that prevents leakage paths while maintaining accurate needle alignment through the tip component's precision guidance features
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 allows smaller fuel injectors to withstand pressures over 200 MPa without stress fractures, improving sealing efficiency and reducing manufacturing costs, while maintaining accurate needle alignment and extending injector life.
Implementation Method 1
The high-pressure containment sleeve and the tip component partially define a nozzle chamber. The method also includes containing pressure inside the nozzle chamber with a wall thickness of the high-pressure containment sleeve.
Implementation Method 2
The method also includes sealing the nozzle chamber by sizing annular sealing lands between the high-pressure containment sleeve and a tip component and an injector stack component, respectively, to have radial widths smaller than the wall thickness of the high-pressure containment sleeve.
Implementation Method 3
The needle valve member includes an opening hydraulic surface exposed to fluid pressure in the nozzle chamber. The needle valve member also includes a closing hydraulic surface that is exposed to fluid pressure in a needle control chamber.
Data Source
AI summary
A nozzle assembly for a fuel injector capable of withstanding high-pressures includes a nozzle chamber defined by a high-pressure containment sleeve, a tip component defining a nozzle outlet, and an injector stack component. A leakage path is defined between an injector body casing and an outer wall surface of the high-pressure containment sleeve and a needle valve member that opens and closes the nozzle outlet is out of contact with the high-pressure containment sleeve. The high-pressure containment sleeve has a hollow, cylindrical shape and has an inner wall exposed to fluid pressure inside the nozzle chamber that is free of stress concentrating surface features associated with heart shaped cavities in the prior art.