Fuel Injector Magnet Assembly Axial Fixing Element
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Solution Overview
Problem
Existing fuel injector magnet assemblies experience variations in armature closing times due to hydraulic sticking of the residual air gap disc, leading to inconsistent injection durations and quantities, particularly in small injection scenarios, and suffer from material restriction and wear issues.
Innovation Solution
A magnet assembly with a separately designed spring-based fixing element that securely fixes the residual air gap disc in the axial direction, preventing relative movement and ensuring constant armature closing times, allowing for free material choice and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the residual air gap disc is arranged in a freely floating manner and centered via its outer circumference, then the assembly is simple and material choice is flexible, but hydraulic sticking occurs during operation causing variable closing times and injection quantity spreads
Solution Approach 1:
A non-magnetic fixing element is introduced as an intermediary component between the residual air gap disc and the armature/magnetic core. This fixing element serves as a mediator that prevents direct contact and relative movement between the disc and magnetic components, thereby eliminating hydraulic sticking while maintaining the disc's functional role in defining the air gap.
Solution Approach 2:
The magnet assembly is segmented into distinct functional components: the residual air gap disc remains responsible for defining the air gap distance, while the separately designed fixing element is dedicated solely to preventing relative movement and hydraulic sticking. This segmentation allows each component to perform its specific function optimally without interference.
2Reliability
If projections are added to the residual air gap disc to fix its position, then closing time consistency improves, but material choice is restricted and wear of projections reduces service life
Solution Approach 1:
The fixing element acts as an intermediary that prevents direct contact between the residual air gap disc and the armature or magnetic core. By introducing this intermediate component, the disc itself does not require modifying features like projections, thereby avoiding wear on the disc and extending its service life while still achieving consistent closing times.
Solution Approach 2:
The fixing element is designed as a separate, replaceable component that absorbs the wear and operational stresses. This allows the more critical and potentially more expensive residual air gap disc to remain intact and durable, while the fixing element can be easily replaced if needed, effectively sacrificing a simpler component to protect the integrity of the disc.
3Reliability
If the residual air gap disc is fixed axially by a fixing element, then hydraulic sticking is prevented and closing times become constant, but the device structure becomes more complex
Solution Approach 1:
The non-magnetic fixing element serves as a dedicated intermediary component that specifically addresses the hydraulic sticking problem by preventing direct contact between the residual air gap disc and magnetic components. This targeted intervention provides a simple yet effective solution to the sticking issue without requiring complex redesign of the entire magnet assembly.
Solution Approach 2:
The fixing element, while primarily designed to prevent relative movement and hydraulic sticking, also serves additional functions: it centers the residual air gap disc axially, maintains proper positioning during assembly, and prevents direct contact between the disc and magnetic components. This multi-functionality justifies the addition of the component by providing multiple benefits from a single element.
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 ensures consistent injection durations and quantities, minimizes wear, and allows for reliable fuel injector operation without the need for structural changes, correcting only for wear-related drifts, and enabling independent material selection for the fixing element and residual air gap disc.
Implementation Method 1
The fixing element is designed as a spring element that is prestressed parallel to the longitudinal axis of the magnet assembly. A spring element can be an elastically or also partially plastically restoring element that deforms under load and can return to its original shape after relief.
Implementation Method 2
The electromagnet has a magnetic coil and a magnetic core. The anchor has an anchor plate and an anchor bolt. A residual air gap washer (RLSS) may be provided between the armature plate and the magnetic core.
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
The invention relates to a magnet assembly (3) for a fuel injector (1). The magnet assembly (3) comprises an electromagnet (5) having a magnet core (7) and a magnet coil (9). The magnet assembly (3) further comprises an armature (17) for moving a valve member and a residual air gap disc (25) for setting a spacing between the magnetic core (7) and the armature (17). The residual air gap disc (25) is arranged between the electromagnet (5) and the armature (17). Furthermore, the residual air gap disc (25) is fixed in a direction parallel to a longitudinal axis (35) of the magnet assembly (3) by a fixing element (29). The fixing element (29) is designed as a separate item from the residual air gap disc (25).