High Pressure Fuel Pipe Connection Arrangement for Injector Holder
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Solution Overview
Problem
The existing high pressure fuel connection arrangement to an injector holder in common rail systems for large internal combustion engines is unreliable due to limited thread engagement, leading to insufficient sealing force and a shortened component lifecycle, especially under high pressures and varying operating conditions.
Innovation Solution
A connection arrangement featuring a chamber in the cylinder head with fixing means that exerts force through an enlarged counter surface on the pipe, allowing for a longer pipe length and reduced strain, enabling better sealing and leakage collection, with optional supporting elements and ducts for leakage management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct threaded connection is used between pipe and injector holder, then connection simplicity is improved, but sealing reliability deteriorates due to limited thread engagement length
Solution Approach 1:
A chamber is introduced as an intermediary component between the pipe and injector holder. The chamber receives the pipe with sufficient axial play and provides a separate threaded connection to the injector holder, thereby decoupling the pipe connection from direct threading into the narrow injector holder wall.
Solution Approach 2:
The solution moves the threaded connection from the radial dimension (direct threading into injector holder wall) to the axial dimension (chamber threaded into injector holder, pipe threaded into chamber). This dimensional shift allows for adequate thread engagement length without increasing radial complexity.
2Ease of manufacture
If threads are provided to the narrow wall section of injector holder, then direct connection is achieved, but component lifecycle deteriorates due to manufacturing difficulty and stress concentration
Solution Approach 1:
The chamber serves as a mediator that relocates the threading operation from the narrow injector holder wall to a more accessible location on the chamber itself, which has sufficient wall thickness for proper thread formation and reduced stress concentration.
3Reliability
If pipe length is increased to reduce strain, then sealing reliability is improved, but device complexity increases due to need for chamber and fixing means
Solution Approach 1:
The chamber is designed to perform multiple functions simultaneously: it provides a mounting interface for the pipe, serves as a leakage collection chamber, and acts as a structural element connecting to the injector holder. This multi-functionality justifies the added component without proportionally increasing overall system complexity.
Solution Approach 2:
The leakage collection function is merged with the structural chamber that provides pipe mounting and connection to the injector holder. Instead of adding a separate leakage collection device, the chamber itself serves dual purposes, thereby reducing net complexity increase.
4Difficulty of detecting and measuring
If chamber diameter is increased to collect leakage, then leakage detection capability is improved, but device complexity increases
Solution Approach 1:
The chamber's primary structural function of mounting the pipe and connecting to the injector holder is combined with a secondary leakage collection function. By designing the chamber with sufficient diameter, it simultaneously serves as both a mechanical support structure and a leakage reservoir, eliminating the need for separate leakage collection components.
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 solution provides a reliable and durable connection that maintains sealing integrity under varying conditions, allows for efficient leakage detection, and extends component lifespan by distributing strain effectively and managing thermal changes.
Implementation Method 1
the fixing means exerting the fixing force through an enlarged part with suitable counter surface arranged in the second pipe means
Implementation Method 2
The length of the second pipe means between the fixing means and the injector holder and the diameter of the chamber are selected so as to allow slight bending of the second pipe means located therein under certain strain caused by the fixing means. The use of pipe means with a long loaded length provides a better retained strain when pipe working lengths change due to thermal loading changes.
Data Source
Figure 1
AI summary
The invention relates to a high pressure fuel connection arrangement to an injector holder (2) in a common rail system for a large internal combustion engine, comprising a first pipe means (3) for supplying the high pressure fuel provided by a common rail system into the cylinder head (1) of the engine and a second pipe means (4) for supplying the high pressure fuel further within the cylinder head (1) into the injector holder (2) to be injected into a cylinder of the engine. A first end (4a) of the second pipe means (4) is connected with the first pipe means (3) and the second end (4b) of the second pipe means (4) is in direct connection with said injector holder (2). The arrangement includes fixing means (7) arranged in threaded connection with a first part of (5) of a chamber (5,6) in the cylinder head for fixing the second pipe means (4) tightly to the injector holder (2), the fixing means (7) exerting the fixing force through an enlarged part (4c) with suitable counter surface (4d) arranged in the second pipe means (4). Said chamber (5,6) is arranged in communication with the injector holder (2) through a second part (6) of the chamber (5,6), the second pipe means (4) being at least of substantial length spaced apart from said chamber (5,6) between the fixing means (7) and the injector holder (2).