Fuel Injection Needle Gap Forming Member Curved Surface Design
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Solution Overview
Problem
Existing fuel injection devices experience variations in fuel injection amount and operational failures due to tilting of the needle axis, leading to increased slide resistance, uneven wearing, and potential operational failures from wear debris.
Innovation Solution
The fuel injection device incorporates a gap forming member that creates an axial gap between the flange and movable core, allowing for controlled collision and reduced slide resistance, with curved surfaces to prevent edge corner catching and wear debris issues, ensuring stable needle reciprocation and consistent fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the needle is supported only at one end by the gap forming member and stationary core, then the needle can reciprocate in the axial direction, but the needle axis may tilt and cause increased slide resistance and uneven wear
Solution Approach 1:
The support function is divided into two segments: the gap forming member provides support at one location while the stationary core provides support at another location. This segmentation allows the needle to be supported at multiple points without requiring a single complex support structure, thereby preventing tilting while maintaining reciprocation capability.
2Device complexity
If cylindrical surfaces are used for sliding contact between the flange, gap forming member, and stationary core, then the structure is simple, but surface-to-surface contact increases slide resistance and causes uneven wear when the needle tilts
Solution Approach 1:
The sliding surfaces are designed with curved profiles rather than simple cylindrical shapes. The flange has a curved outer peripheral surface, the gap forming member has a curved inner peripheral surface, and the stationary core has a curved inner peripheral surface. This curvature allows the surfaces to maintain line contact or point contact even when the needle tilts, reducing slide resistance and preventing uneven wear.
3Device complexity
If outer peripheral edge corners of the flange and gap forming member are used for sliding contact, then the structure is compact, but the edge corners may be caught on the opposing surfaces causing operational failure
Solution Approach 1:
The outer peripheral edge corners of the flange and gap forming member are designed with asymmetric chamfered surfaces. The first and second chamfered surfaces on the flange, and the corresponding chamfered surfaces on the gap forming member, are positioned and angled asymmetrically to ensure that the edge corners do not make contact with the opposing inner peripheral surfaces during reciprocation, thereby preventing catching and operational failure.
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 stabilizes needle reciprocation, reduces variations in fuel injection, and prevents operational failures by minimizing slide resistance and wear debris, ensuring reliable high-pressure fuel injection.
Implementation Method 1
a coil, which generates a magnetic field
Implementation Method 2
the movable core is accelerated in the gap and collides against the flange of the needle
Data Source
AI summary
An inner side wall surface of a gap forming member, which is opposed to a flange outer wall surface of a flange of a needle, is slidable relative to the flange outer wall surface. Also, an outer side wall surface of the gap forming member, which is opposed to a stationary core inner wall surface of a stationary core, is slidable relative to the stationary core inner wall surface. The flange outer wall surface and the outer side wall surface are curved to project in a radially outer direction of a housing in a cross section thereof taken along an imaginary plane, which includes an axis of the housing.