Closure Bolt Insert Design for High-Pressure Fuel Systems
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Solution Overview
Problem
The existing closure bolt design for modular common-rail fuel injection systems faces challenges in production due to complex geometries, particularly for the throughflow limiter, which makes it difficult to achieve durability at system pressures over 1600 bar.
Innovation Solution
The closure bolt is designed in two parts, with the throughflow limiter integrated into an insert that bears the sealing surface, allowing for easier production of the main body and eliminating the need for a closure screw, enabling simpler adaptation of the flow rate and reducing pressure fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the closure bolt has a continuous axial high-pressure bore with the throughflow limiter integrated into the main body, then the structure is compact and functional, but the manufacturing complexity increases significantly and durability at pressures over 1600 bar becomes difficult to achieve
Solution Approach 1:
The closure bolt is divided into two separate parts: the main body and an insert. The insert contains the throughflow limiter and is inserted into the high-pressure bore of the main body. This segmentation allows the main body to be manufactured with simpler geometry suitable for high-pressure applications, while the complex throughflow limiter geometry is confined to the separate insert, thereby reducing overall manufacturing complexity and improving durability.
2Productivity
If the closure bolt has a continuous axial high-pressure bore, then fuel flow is simplified, but the inner contour is subjected to full high-pressure fuel pressure over the entire length, requiring high manufacturing quality that is difficult to achieve
Solution Approach 1:
By separating the closure bolt into main body and insert, the high-pressure bore in the main body can be manufactured with appropriate radii and surfaces to withstand full high-pressure fuel pressure, while the insert contains the geometrically complex throughflow limiter that would be difficult to manufacture with high precision under pressure.
3Reliability
If the closure bolt uses a closure screw to seal the high-pressure bore, then sealing is achieved, but the risk of manipulation by unauthorized persons increases
Solution Approach 1:
The closure screw is completely removed from the design. Instead, the insert itself provides the sealing function through its first sealing surface that closes the high-pressure bore from the inside, eliminating the external closure screw that could be manipulated by unauthorized persons while maintaining sealing reliability.
4Device complexity
If the throughflow limiter is integrated into the main body of the closure bolt, then the structure is unified, but adapting the closing flow rate to different requirements becomes complex
Solution Approach 1:
The insert containing the throughflow limiter is made as a separate, exchangeable component. This allows different inserts with different throughflow limiter geometries to be used with the same main body, enabling easy adaptation of the closing flow rate to different requirements without redesigning the entire closure bolt.
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 simplifies production, enhances durability, and allows for easy exchange of inserts to adapt the flow rate, reducing the risk of manipulation and maintaining high-pressure integrity.
Implementation Method 1
a bolt-like portion which can be inserted into an opening of the injector and which has a first, preferably conical sealing surface for closing the opening in a high-pressure-tight manner
Implementation Method 2
a throughflow limiter for limiting the flow rate of fuel delivered into the injector
Implementation Method 3
the bolt-like portion has a high-pressure bore which is hydraulically connected to the high-pressure port and which issues into the injector
Data Source
AI summary
A closure bolt for an injector of a modular common-rail fuel injection system includes at least one high-pressure port for high-pressure fuel and a bolt-like portion which is configured to be inserted into an opening of the injector and which has a first, preferably conical, sealing surface for closing the opening in a high-pressure-tight manner. The bolt-like portion has a high-pressure bore which is hydraulically connected to the high-pressure port and which issues into the injector. The closure bolt further includes a throughflow limiter configured to limit the flow rate of fuel delivered into the injector. The bolt-like portion has an insert in which the throughflow limiter is formed and which bears the first sealing surface.