Fuel Injector Nozzle Assembly Merging Needle and Throttle Bore
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Solution Overview
Problem
Existing nozzle assemblies for fuel injectors in internal combustion engines are not functionally and production-optimized, particularly for directly switched diesel injection systems, as they require complex assembly and are sensitive to temperature and tolerance variations.
Innovation Solution
A nozzle assembly with a nozzle needle guided in a high-pressure bore, where the throttle bore body is axially prestressed by a closing spring, enhancing the hydraulic closing force with a pressure differential across throttle bores, and featuring a one-piece design for simplified assembly and reduced component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional nozzle assembly design with separate throttle components is used, then the assembly provides basic fuel injection function, but the assembly complexity and number of components increases
Solution Approach 1:
The patent combines the throttle bore body and nozzle needle into a single integrated component. The throttle bore is formed directly in the nozzle needle, eliminating the need for separate throttle components and reducing assembly complexity while improving temperature stability through fewer interfaces and connections.
2Ease of manufacture
If multiple separate components are used in the nozzle assembly, then each component can be optimized independently, but the number of components and assembly steps increases
Solution Approach 1:
The throttle bore body and nozzle needle are merged into one component with the throttle bore formed directly in the needle. This integration reduces the component count and simplifies assembly while maintaining manufacturing optimization through precise single-component fabrication.
3Force
If the nozzle needle outer diameter is reduced to improve hydraulic force ratio, then the hydraulic closing force increases, but the structural strength and guidance stability may be compromised
Solution Approach 1:
The nozzle needle features local quality variations with different outer diameters at different sections. The reduced outer diameter D3 in the throttle bore area optimizes hydraulic force ratio, while other sections maintain sufficient diameter for structural strength and proper guidance, achieving both hydraulic efficiency and mechanical integrity.
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
The solution results in a compact, easy-to-assemble fuel injector with improved guidance, centering, and sealing capabilities, while reducing the number of components and assembly complexity, and is less sensitive to temperature variations.
Implementation Method 1
The nozzle needle (1) is acted upon at least indirectly by the spring force of a closing spring (8)
Implementation Method 2
The at least one throttle bore has the effect that a hydraulic pressure p1 acts in the first pressure chamber and a hydraulic pressure p2 acts in the second pressure chamber, where p1 > p2. The hydraulic pressure p1 accordingly causes an additional hydraulic closing force
Data Source
Figure 1
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AI summary
The invention relates to a nozzle assembly for a fuel injector having a nozzle needle (1) which is guided with a reciprocating movement over at least one guide section (5, 6) in a high-pressure bore (2) of a nozzle body (3) for opening and closing at least one injection opening (4) and is loaded at least indirectly by the spring force of a closing spring (8), and having a restrictor-bore body (7) which is loaded by spring force in the axial direction. According to the invention, the restrictor-bore body (7) bears against the nozzle needle (1) and is loaded in the axial direction by the spring force of the closing spring (8). Furthermore, the invention relates to a fuel injector having a nozzle assembly of this type.