Fuel Injector Segmented Contacts for Reduced Hydraulic Sticking
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Solution Overview
Problem
Fuel injectors experience sticking effects due to hydraulic contact forces, leading to unreliable and non-repeatable motion cycles, which are exacerbated by minimal contact surfaces that increase stress and reduce lifetime.
Innovation Solution
The fuel injector design incorporates divided contact surfaces, separated by recess portions, to reduce sticking effects by evenly distributing impact forces and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact surface area is minimized to reduce sticking effect, then the sticking effect is reduced, but the stress on contact surfaces increases and lifetime decreases
Solution Approach 1:
The contact surface is divided into multiple separate contact portions (first, second, and third contact portions) rather than using a single continuous surface. This segmentation reduces the sticking effect by breaking up the hydraulic contact force while distributing the load across multiple contact points, thereby reducing stress on individual contact surfaces and extending component lifetime.
2Reliability
If the contact surface area is minimized to reduce sticking effect, then the sticking effect is reduced, but the repeatability of motion cycle deteriorates
Solution Approach 1:
By segmenting the contact surface into multiple portions, the patent reduces hydraulic sticking while maintaining geometric precision. The segmented design allows for more consistent contact engagement across multiple cycles, improving repeatability because each contact portion engages predictably without the variability introduced by minimal narrow surfaces.
Solution Approach 2:
Different contact portions are positioned at different locations (first contact portion engages pintle, second engages pole piece, third engages housing) to create localized contact zones that each provide consistent engagement. This local quality approach ensures repeatable motion cycles by distributing contact precision requirements across multiple controlled locations rather than relying on a single narrow surface.
3Reliability
If a narrow contact surface is used, then the sticking effect is reduced, but the stress concentration increases
Solution Approach 1:
The contact surface is segmented into multiple portions that are distributed across different locations. This segmentation prevents stress concentration by spreading the load across multiple contact points rather than concentrating it on a single narrow surface, while still reducing sticking effect through the broken-up geometry.
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 divided contact surfaces effectively minimize sticking, ensuring reliable operation and extended lifetime by reducing stress on contact points.
Implementation Method 1
a magnetic field is generated by a magnetic coil, which magnetic field is enhanced by a pole piece disposed proximally (i.e. away from the nozzle end of the injector) of the armature and moves the armature away from the nozzle
Data Source
AI summary
A fuel injector comprising:a housing extending axially along an injector axis from a proximal end to a distal end and having a nozzle at the distal end,a pintle having an axially extending pintle shaft, the pintle being axially movable between an open position and a closed position in which it closes the nozzle from the inside,an armature disposed in a cavity of the housing to be axially movable between a proximal position and a distal position and having an axial through-hole in which the pintle shaft is received,a magnetic coil, anda pole piece disposed in the housing-proximally of the armature.At least one axially movable element of the fuel injector comprises a first contact surface for engaging an axially opposite second contact surface of another element. One of the contact surfaces is a divided contact surface.