Fuel Injector Stator Core Slot Design for Eddy Current Reduction
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Solution Overview
Problem
Rising or falling magnetic fields in fuel injector actuators create eddy currents, increasing the time it takes for the nozzle or needle valve element to fully open and close, leading to non-optimized fuel delivery in internal combustion engines.
Innovation Solution
The fuel injector design incorporates a stator core with a radially extending slot and an annular coil assembly, separated by electrically insulating material, which limits contact to only one azimuthal location, preventing eddy currents and reducing the time for magnetic flux density to rise and fall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stator core is positioned in contact with the stator housing at multiple azimuthal locations, then the structural stability is improved, but eddy currents are generated increasing the time for valve element to open and close
Solution Approach 1:
The stator core contact interface is segmented into discrete azimuthal locations rather than continuous contact. The stator core includes protrusions that contact the stator housing at specific segmented points, breaking the continuous conductive path that would otherwise allow eddy currents to form across the entire contact surface.
Solution Approach 2:
An electrically insulating material is introduced as an intermediary between the stator core and stator housing at contact points. This intermediary layer prevents direct electrical contact and eddy current formation while still providing mechanical support and positioning stability for the stator core assembly.
2Productivity
If the magnetic field rises and falls quickly, then fuel delivery efficiency is improved, but eddy currents are generated in the stator core increasing the time for valve element actuation
Solution Approach 1:
The radially extending slot in the stator core, which initially appears to be a structural feature, is utilized to break up eddy current paths. By positioning the slot strategically, the design converts what would be harmful eddy currents into a controlled feature that actually helps reduce their magnitude while maintaining the rapid magnetic field changes needed for efficient fuel delivery.
3Loss of time
If electrically insulating material is added to separate the stator core from the stator housing, then eddy currents are reduced, but device complexity increases
Solution Approach 1:
The electrically insulating material is merged with the stator housing structure itself rather than being a separate component. The insulating material is integrated into the stator housing as a built-in feature, eliminating the need for separate insulating components and reducing assembly complexity while still providing the necessary electrical isolation.
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 design reduces eddy currents, allowing the nozzle or needle valve element to open and close faster, improving fuel delivery efficiency by approximately 50% compared to conventional fuel injectors.
Implementation Method 1
Rising or falling magnetic fields in fuel injector actuators create eddy currents, increasing the time it takes for the nozzle or needle valve element to fully open and close
Implementation Method 2
an annular coil assembly positioned between the first annulated wall and the second annulated wall
Data Source
AI summary
A fuel injector includes an injection control valve having a stator core that is electrically isolated from surrounding parts such as a stator housing. The stator core includes a first annulated wall having an inner surface, a second annulated wall having an outer surface, a radially extending wall connecting the first and second annulated wall, and a radially extending slot extending through the first annulated wall, the radially extending wall, and the second annulated wall. The stator core may include a limited number of contact points with the stator housing. Alternatively or additionally, an electrically insulating material may be placed between the stator core and the stator housing.