Fuel Injector Tip Sac Region Mound Design
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Solution Overview
Problem
Conventional fuel injectors experience fuel dribble during and after discharge events due to high operational forces, leading to reduced service life and poor emission quality, with existing solutions like insert displacement in the sac region not effectively addressing these issues.
Innovation Solution
The design of a fuel injector tip with a convex mound on its interior surface, extending along the axis of the sac region and terminating before the orifice perimeter, reduces the sac region's volume and minimizes fuel dribble by ensuring efficient fuel metering and discharge, while also providing additional strength to withstand operational forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an insert is positioned in the sac region to reduce volume, then fuel dribble is reduced, but the insert may be displaced under high pressure reducing service life
Solution Approach 1:
The patent merges the insert function with the injector tip body by integrally forming the mound structure as part of the tip itself. This eliminates the separate insert component that could be displaced, while maintaining the volume reduction function. The mound is formed as a unified structure with the tip, ensuring it cannot be displaced under high pressure while still reducing sac region volume to minimize fuel dribble.
Solution Approach 2:
The mound structure is pre-formed as an integral part of the injector tip during manufacturing. This preliminary formation ensures the structure is in place before operation, eliminating the need for separate inserts that could be displaced. The integral design is established beforehand to withstand operational pressures without displacement.
2Object-generated harmful factors
If the sac region volume is reduced to minimize fuel dribble, then emission quality improves, but the structural strength to withstand operational forces may be compromised
Solution Approach 1:
The patent applies local quality by creating a mound structure with specific geometric properties in the sac region. The mound has a rounded apex and extends along the axis, providing localized volume reduction for better fuel metering and reduced dribble, while the integral formation with the tip body ensures adequate structural strength is maintained in this critical region.
Solution Approach 2:
The mound structure features a rounded apex and curved surfaces rather than sharp edges or flat surfaces. This spheroidal geometry reduces stress concentration points that would weaken the structure, allowing the sac region to be compacted for reduced dribble while maintaining structural integrity to withstand high operational forces.
3Productivity
If a convex mound is integrally formed on the interior surface, then fuel metering is optimized and dribble reduced, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes fuel metering by controlling the geometric parameters of the mound structure - specifically the apex radius (0.002-0.006 inches), height (0.003-0.008 inches), and extension distance (0.005-0.015 inches). By precisely controlling these parameters, the mound provides optimized fuel flow characteristics while remaining manufacturable through standard precision machining or molding processes.
Data Source
AI summary
An injector tip for a fuel injector includes an exterior surface, and an interior surface defining a sac region therein. The injector tip is also configured to define at least one orifice radially extending from the interior surface to the exterior surface. The orifice is disposed in communication with the sac region located adjacent to the interior surface. Further, the injector tip also includes a mound that is defined on the interior surface such that the mound is integrally formed with the interior surface adjacent to the sac region. The mound is configured to extend along an axis of the sac region and terminate prior to a perimeter of the at least one orifice.