Multi-Piece Throttle Bore Body for Fuel Injector Leakage Reduction
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Solution Overview
Problem
Existing nozzle assemblies for fuel injectors in internal combustion engines face inefficiencies due to leakage and manufacturing tolerances, which affect sealing and response behavior, leading to suboptimal fuel injection performance.
Innovation Solution
A multi-piece throttle bore body with radially guided sleeves and a floating mounting system reduces leakage by displacing the leakage-afflicted guide region inward, compensates for assembly tolerances, and utilizes pressure differences to minimize guide play and enhance sealing, while a pot-shaped sleeve configuration optimizes flow and hydraulic force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-piece throttle bore body is used, then the structure is simple, but leakage occurs in the guide region
Solution Approach 1:
The throttle bore body is divided into multiple pieces (first throttle bore body and second throttle bore body) that are guided into one another. This segmentation allows the guide region to be separated from the sealing region, enabling the guide play to be minimized without compromising the overall structural simplicity. The multiple pieces can be manufactured with tighter tolerances in critical sealing areas while maintaining ease of assembly.
2Ease of manufacture
If the guide region is enlarged to accommodate manufacturing tolerances, then assembly is easier, but leakage increases
Solution Approach 1:
The guide region is displaced radially inward to a different spatial location within the throttle bore body structure. This dimensional repositioning allows the guide play to occur in a region that does not directly affect the sealing interface, thereby compensating for manufacturing tolerances without increasing leakage. The guide region and sealing region are spatially separated in the radial dimension.
3Manufacturing precision
If a fixed mounting system is used, then assembly is precise, but manufacturing and assembly tolerances cannot be compensated
Solution Approach 1:
The mounting system is designed to be dynamically adjustable within certain limits. The first and second throttle bore bodies are guided into one another with controlled play, allowing them to self-align and compensate for manufacturing tolerances during assembly and operation. This dynamic adaptation maintains precise sealing contact while accommodating variations in manufacturing precision.
4Ease of operation
If guide play between sleeves is increased, then assembly is easier, but leakage increases and efficiency decreases
Solution Approach 1:
Different regions of the throttle bore body are given different quality characteristics. The guide region between the first and second throttle bore bodies is designed with specific guide play characteristics that facilitate assembly, while the sealing regions are designed with tight tolerances and hydraulic pressure forces that minimize leakage. This local differentiation of quality allows easy assembly without compromising injection efficiency.
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 significantly reduces leakage, improves sealing, and enhances the response behavior of moving components, leading to more efficient and rapid needle closure, thus optimizing the nozzle assembly's efficiency and production simplicity.
Implementation Method 1
a hydraulic pressure p1 prevails in the first part region which lies upstream in the flow direction of the fuel in relation to the second part region, and a hydraulic pressure p2 prevails in the second part region, which hydraulic pressure p2 is smaller than p1
Implementation Method 2
Since p2 is smaller than p1, the sleeves are pressed against one another in the radial direction, with the result that the leakage in the region of the guide is reduced further in this way
Implementation Method 3
The nozzle needle is loaded in the closing direction by the spring force of a closing spring which is supported on one side on a body component of the fuel injector and on the other side on a throttle bore body
Implementation Method 4
Said measures, in each case on their own or in combination, lead to a hydraulic pressure force which acts in the closing direction in addition to the spring force of the closing spring and accelerates the closing operation being generated on the throttle bore body and therefore on the nozzle needle
Data Source
AI summary
A nozzle assembly for a fuel injector includes a nozzle needle (1), which is accommodated in a high-pressure bore (2) of a nozzle body (3) in such a way that the nozzle needle can be moved in a reciprocating manner in order to open and close at least one injection opening (4) and to which a spring force of a spring (5) is applied at least indirectly in a closing direction. The nozzle needle (1) is at least partially surrounded by a throttle bore body (7) in order to form at least one closing throttle (6). The throttle bore body (7) has a multi-part design and comprises at least two sleeves (7.1, 7.2), which are at least partially guided in each other.