Fuel Injector Connection Nut Metal-to-Metal Sealing
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Solution Overview
Problem
Current fuel injection systems face challenges in maintaining a fuel-tight seal at elevated pressures above 35 MPa, particularly when using elastomeric O-rings, and metal-to-metal sealing arrangements are impractical for integrally formed fuel rails or injectors, risking fuel leakage and damage to internal components.
Innovation Solution
A fuel system design featuring a fuel injector with a metal inlet conduit and a fuel distribution conduit connected using a connection nut and a retention member with complementary threads, allowing for a robust metal-to-metal sealing interface that accommodates increasing pressures without altering the fuel rail's design, thus minimizing manufacturing changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomeric O-rings are used for sealing between fuel injector and fuel distribution conduit, then sealing is adequate for pressures below 35 MPa, but sealing becomes difficult and unreliable at elevated pressures above 35 MPa
Solution Approach 1:
The patent transitions from elastomeric material (O-ring) to metal material for the sealing interface. This parameter change in material properties enables the sealing surface to withstand elevated pressures above 35 MPa while maintaining sealing reliability, as metal does not deform or degrade under high pressure like elastomeric materials do.
Solution Approach 2:
The sealing structure combines metal components (fuel injector inlet conduit and fuel distribution conduit) with a metal-to-metal sealing interface. This composite approach using metal materials throughout the sealing path provides the necessary strength and pressure resistance for high-pressure fuel injection systems while maintaining reliable sealing.
2Reliability
If metal-to-metal sealing arrangements with radially enlarged region and connection nut are used, then robust sealing is achieved at high pressures, but the arrangement requires deformation of the conduit or fixing another component which may damage internal components or alter fuel spray characteristics
Solution Approach 1:
The patent divides the sealing system into separate, modular components: the fuel injector inlet conduit with its sealing surface, the fuel distribution conduit with external threads, and the connection nut. This segmentation allows each component to be manufactured independently using standard processes without requiring deformation or additional fixing operations, eliminating the risk of damaging internal components while maintaining robust sealing.
Solution Approach 2:
Instead of deforming the fuel distribution conduit to create a radially enlarged region (as in conventional arrangements), the patent inverts the approach by providing external threads directly on the conduit and using a connection nut with internal threads. This reversal of the conventional approach eliminates the need for deformation operations and associated risks while achieving the same sealing objective.
3Reliability
If multiple interfaces are sealed in metal-to-metal arrangements, then sealing is achieved, but the risk of fuel leakage increases
Solution Approach 1:
The patent extracts and eliminates unnecessary sealing interfaces from the system. By using a direct metal-to-metal sealing surface between the fuel injector inlet conduit and fuel distribution conduit, combined with the threaded connection, the design reduces the number of sealing interfaces to the minimum required, thereby reducing the cumulative risk of fuel leakage while maintaining effective sealing.
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 provides a robust, leak-proof connection at elevated pressures while allowing for minimal design changes to existing fuel injector designs, ensuring efficient fuel delivery and reducing the risk of fuel leakage.
Implementation Method 1
a connection nut having connection nut internal threads which are complementary to, and are threadably engaged with, the fuel distribution conduit external threads
Implementation Method 2
tightening of the connection nut to the fuel distribution conduit causes a fuel-tight connection between the fuel injector and the fuel distribution conduit
Data Source
AI summary
A fuel system includes a fuel injector having an inlet conduit which extends along an inlet conduit axis and has an inlet conduit shoulder which is travers to the inlet conduit axis. A fuel distribution conduit supplies fuel to the fuel injector, extends along a fuel distribution conduit axis, and has external threads which threadably engage internal threads of a connection nut. A retention member is a segment of an annulus and includes a central passage extending axially therethrough and external threads which threadably engage the internal threads of the connection nut. The retention member is terminated in a direction circumferentially about the fuel distribution conduit axis by first and second end surfaces which together form a retention member slot therebetween sized to permit the inlet conduit to pass therethrough in a direction perpendicular to the fuel distribution conduit axis.