Fuel Injection Valve Magnetic Path Integration
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Solution Overview
Problem
Conventional fuel injection valves face challenges in minimizing mounting length and improving magnetic efficiency while preventing sliding defects of the valve body, particularly due to axial deviation and deformation issues during assembly.
Innovation Solution
A fuel injection valve design featuring a radially slidable contact between the cap and housing, with a cap press-fitted onto a core assembly, preventing stress on weak portions and ensuring magnetic connection, achieved through a two-step hollow cylindrical housing and laser welding to secure the magnetic path and reduce assembly-induced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the facing length L1 of the holder and housing is lengthened to compensate magnetic loss due to gap, then magnetic efficiency is improved, but the mounting length L2 is relatively lengthened
Solution Approach 1:
The holder and housing are integrated into a single piece structure, eliminating the gap between them and the need for separate magnetic path compensation. This merging reduces the mounting length while maintaining magnetic efficiency through the continuous magnetic path provided by the integrated structure.
Solution Approach 2:
The valve body is designed with radial slidability, allowing it to dynamically adjust its position during assembly and operation. This dynamic capability enables the valve body to accommodate axial deviations without requiring excessive clearance, thereby reducing the overall mounting length while maintaining proper magnetic coupling.
2Loss of energy
If the cap and housing are press-fitted with strong load to reduce magnetic loss, then magnetic efficiency is improved, but deformation is generated at weak strength portion such as holder thinned portion
Solution Approach 1:
The holder and housing are merged into one integrated component, eliminating the interface between them. This integration removes the source of magnetic loss that would otherwise require strong press-fitting, while simultaneously protecting weak portions like the thinned section from deformation by eliminating the need for high assembly loads.
Solution Approach 2:
The integrated holder-housing structure inherently cushions and distributes assembly loads, preventing concentration of stress at weak portions. The continuous structure acts as a built-in cushion that protects the thinned portion of the holder from deformation during the assembly process.
3Loss of energy
If three components (cap, core assembly, housing) are press-fitted at three places to reduce magnetic loss, then magnetic efficiency is improved, but assembly complexity increases and deformation risk increases
Solution Approach 1:
The holder and housing are combined into a single integrated component, reducing the number of separate parts from three to two. This merging simplifies the assembly process by eliminating one press-fit operation and reduces the number of interfaces where magnetic loss could occur, while also decreasing the overall complexity of the assembly procedure.
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 design results in a fuel injection valve with enhanced magnetic efficiency, reduced mounting length, and improved injection performance while preventing sliding defects, with cost-effective manufacturing and reduced component tolerance.
Implementation Method 1
a magnetic field generated by a coil 2 generates magnetic suction force
Implementation Method 2
magnetic suction force that suctions the armature 9 to a core 3 side
Implementation Method 3
the valve body 8 is pressed to a valve seat 10 by a spring 13 when the valve is closed
Data Source
AI summary
A fuel injection valve includes: a holder which accommodates a valve body, has a surface magnetically facing the outer periphery of an armature, and is joined to a core; a housing which is press-fitted onto the outer periphery of the holder and accommodates a coil; and a cap which covers the fuel upstream side of the coil in a lid shape and is press-fitted onto the outer periphery of the core. The lower surface of the cap is brought into contact with the upper end surface of the housing in a radially slidable state and then an outer peripheral portion of a contact surface between the cap and the housing is joined by laser welding.