Solenoid Actuator Non-Magnetic Insert Residual Magnetism
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Solution Overview
Problem
Fuel injectors in common rail systems face challenges in accurately injecting varying fuel volumes at precise timings while maintaining robustness and consistency in the hostile environment of an internal combustion engine, particularly in achieving low emissions and high performance across a wide range of engine operating conditions.
Innovation Solution
The solenoid actuator includes a stator assembly with a fragile highly magnetic core and a non-magnetic insert that moves into and out of contact with the armature assembly, maintaining a sliding air gap and reducing residual magnetism to improve performance and prevent core breakage, while a direct operated check valve and needle control valve manage fuel injection events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fragile highly magnetic core is used in the solenoid actuator, then magnetic performance and injection precision are improved, but the core is susceptible to breakage under mechanical stress
Solution Approach 1:
The patent employs a composite structure combining a fragile highly magnetic core material with a more robust protective housing and support mechanisms. The core itself is made of high-permeability magnetic material optimized for magnetic performance, while the overall assembly integrates structural supports and protective elements that prevent mechanical damage while preserving the core's magnetic properties for precise injection control
Solution Approach 2:
The patent incorporates protective housing and support structures that are designed beforehand to cushion and protect the fragile magnetic core from mechanical stress and potential breakage. These protective elements are integrated into the solenoid actuator assembly before operation, providing preemptive protection while allowing the core to maintain its optimized magnetic characteristics
2Measurement precision
If a non-magnetic insert is introduced to reduce residual magnetism, then injection accuracy for small fuel volumes is improved, but device complexity increases
Solution Approach 1:
The patent introduces a non-magnetic insert as an intermediary element positioned between the magnetic core and the armature or housing. This insert serves as a mediator that disrupts residual magnetic flux paths, preventing unwanted residual magnetism from affecting the next injection cycle. The insert is strategically placed to intercept and redirect magnetic field lines, ensuring clean magnetic separation while maintaining a relatively simple overall structure
Solution Approach 2:
The non-magnetic insert is placed specifically in the regions where residual magnetism would most adversely affect performance, such as near the armature interface or flux return paths. This localized application of non-magnetic material addresses the residual magnetism problem only where it occurs most critically, rather than requiring complete redesign of the entire magnetic circuit, thus limiting the increase in device complexity
3Loss of time
If the solenoid actuator is designed for high speed operation to meet precise injection timing, then injection timing precision is improved, but reliability under hostile engine conditions deteriorates
Solution Approach 1:
The patent designs the solenoid actuator with dynamic characteristics optimized for high-speed operation, including lightweight moving parts, minimized friction surfaces, and magnetic circuit geometries that enable rapid flux establishment and collapse. The armature and plunger are designed with reduced mass and optimized magnetic path lengths to achieve fast response times for precise injection timing while incorporating features like lubrication systems and thermal management to maintain reliability under repeated high-speed cycling in hostile engine environments
Solution Approach 2:
The solenoid actuator is segmented into distinct functional modules - the magnetic circuit section, the mechanical drive section, and the sealing section - each optimized independently. This segmentation allows the magnetic core and coil to be designed for maximum speed response, while the mechanical and sealing components are separately engineered for durability and reliability under engine conditions, with interfaces designed to minimize stress concentration and facilitate maintenance
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 configuration enhances the solenoid actuator's ability to accurately control fuel injection, reduces residual magnetism, and protects the magnetic core from breakage, enabling efficient and precise fuel injection, including small post-injection quantities following a main injection event, thereby improving performance and reliability.
Implementation Method 1
A coil winding is positioned around the fragile highly magnetic core
Implementation Method 2
A fragile highly magnetic core extends between a top end and an armature end
Data Source
AI summary
In one aspect, a fuel injector includes an injector body that defines a fuel inlet, a drain outlet and a nozzle outlet. A direct operated check valve is positioned in the injector body and includes a needle valve member with an opening hydraulic surface exposed to fluid pressure in a nozzle supply passage, and a closing hydraulic surface exposed to fluid pressure in a needle control chamber. The needle valve member is movable between a first position at which the nozzle supply passage is blocked to the nozzle outlet, and a second position at which the nozzle supply passage is open to the nozzle outlet. A needle control valve is positioned in the injector body and includes a control valve member movable between a first position at which the needle control chamber is fluidly connected to the drain outlet, and a second position at which the needle control chamber is fluidly blocked to the drain outlet. A solenoid actuator is positioned in the injector body and includes a stator assembly and an armature assembly coupled to the control valve member. One of the stator assembly and the armature assembly includes a non-magnetic insert that moves into and out of contact with another of the stator assembly and the armature assembly at an energized position and a de-energized position, respectively.