Fuel Injector Inlet Structure for Interference-Free Press Fitting
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Solution Overview
Problem
The interference between press-fit tolerances of the fuel filter and orifice member in existing electromagnetic fuel injection valves leads to reduced functionality due to distortion of the inner peripheral surfaces, resulting in gaps and decreased performance.
Innovation Solution
The design features a first and second press-fitted cylindrical surface with a stepped part, a press-fitting guide cylinder, and a flange-shaped outer side end wall to maintain proper press-fit tolerances and prevent distortion, ensuring reliable fixation and sealing of the fuel filter and orifice member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fuel filter and orifice member are press-fitted onto the same diameter inner peripheral surface of the fuel inlet cylinder, then the structure is simplified, but the press-fit tolerances interfere with each other causing distortion and gaps
Solution Approach 1:
The inner peripheral surface of the fuel inlet cylinder is divided into two distinct press-fitted cylindrical surfaces with different diameters. The first press-fitted cylindrical surface has a smaller diameter for the fuel filter, while the second press-fitted cylindrical surface has a larger diameter for the orifice member. This segmentation allows each component to have its own dedicated press-fit surface, eliminating tolerance interference and distortion issues that would occur if both components were press-fitted onto the same surface.
2Ease of operation
If the orifice member is press-fitted with a larger press-fit tolerance to facilitate assembly, then the ease of assembly is improved, but the distortion of the inner peripheral surface affects the press-fitting location of the fuel filter
Solution Approach 1:
The inner peripheral surface is segmented into two separate press-fitted cylindrical surfaces, allowing the orifice member to be press-fitted onto the second surface with a larger, more forgiving tolerance without affecting the fuel filter's press-fitting location on the first surface. This eliminates the distortion problem that would occur with a single shared surface.
Solution Approach 2:
Different regions of the inner peripheral surface are given different diameters and press-fit characteristics. The first press-fitted cylindrical surface is optimized for the fuel filter with appropriate tolerance, while the second press-fitted cylindrical surface is optimized for the orifice member with larger tolerance for ease of assembly. Each local region has quality tailored to its specific component's requirements.
Data Source
AI summary
In an electromagnetic fuel injection valve (I), when a fuel filter (20) and an orifice member (21) are press-fitted onto an inner peripheral surface of the fuel inlet cylinder part (7), interference between press-fit tolerances of the fuel filter (20) and the orifice member (21) is prevented, and reliable press-fitting fixation is ensured. A first press-fitted cylindrical surface (23) onto which the fuel filter (20) is press-fitted, and a second press-fitted cylindrical surface (24) contiguous with an outer end of the first press-fitted cylindrical surface (23) via a stepped part (25) and having a larger diameter than that of the first press-fitted cylindrical surface (23) and onto which the orifice member (21) is press-fitted are formed on the inner peripheral surface of the fuel inlet cylinder part (7).