Fuel-Rail Assembly With Adapter For Wide Flow And High-Pressure Sealing
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Solution Overview
Problem
Existing fuel injector sealing methods are unreliable at high pressures due to elastomer O-rings failing under engine conditions, and current thread sizes for connecting injectors to fuel rails either restrict flow or complicate assembly.
Innovation Solution
A fuel-rail assembly with an adapter that allows for a larger thread size (e.g., M14) without enlarging the injector, using a snap ring and clamp force to maintain a fluid-tight connection and facilitate assembly, while avoiding material bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an M14 thread is used on the inlet section to allow for a larger inlet fuel path, then the flow passage and maximum possible injection quantity are improved, but the assembly process becomes more difficult due to the larger outer diameter requiring a larger inner diameter of the solenoid
Solution Approach 1:
The inlet section is divided into two functional parts: the thread portion with M14 threading for fuel flow, and the solenoid mounting portion with a reduced outer diameter. This segmentation allows the thread size to be increased for better fuel flow while the solenoid mounting area is optimized for easy assembly, resolving the contradiction between injection quantity and assembly ease.
2Ease of manufacture
If an M12 thread is used to maintain a compact injector size and ease of assembly, then the assembly process remains simple, but the inlet fuel path diameter is reduced, limiting the flow passage and maximum injection quantity
Solution Approach 1:
The inlet section is divided into two functional parts: the thread portion with M14 threading for fuel flow, and the solenoid mounting portion with a reduced outer diameter. This segmentation allows the thread size to be increased for better fuel flow while the solenoid mounting area is optimized for easy assembly, resolving the contradiction between injection quantity and assembly ease.
3Ease of manufacture
If elastomer O-rings are used for sealing at high pressure, then the sealing method is simple to implement, but the reliability deteriorates under engine environment conditions with cycling pressure, chemical aggression, and temperature fluctuation
Solution Approach 1:
The sealing method is changed from elastomer O-rings to a metal-to-metal sphere-cone contact interface. This parameter change in material selection (from elastomer to metal) and sealing geometry (from radial O-ring to axial sphere-cone) provides reliable sealing at 600 bar and above under engine environment conditions while maintaining ease of implementation through a straightforward mechanical interface.
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
Enables a wide flow path and easy assembly of injectors, ensuring reliable sealing at high pressures without the need for re-designing the injector components.
Implementation Method 1
The clamp force acts in the axial direction to provide a fluid-tight connection between the inlet channel and the outlet channel
Implementation Method 2
at least one intermediate element is elastically deformable to be movable into the recess
Data Source
AI summary
A fuel-rail assembly, comprisingan injector having a proximally disposed inlet portion defining an inlet channel and extending along an axial direction,a fuel rail connected to the inlet portion via an outlet portion that defines an outlet channel,a nut element having an inner thread and at least indirectly engaging the outlet portion to transfer an axial clamp force by which a first contact surface of the inlet portion is pressed against a second contact surface of the outlet portion to provide a fluid-tight connection between the inlet channel and the outlet channel.In order to enable a wide flow path into an injector while maintaining an easy assembly process of the injector, the fuel-rail assembly comprises an adapter with an axially extending through-opening in which the inlet portion is at least partially received.