Fuel Filler Pipe Retainer Segmentation for Corrosion and Precision
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Solution Overview
Problem
The existing fuel filler pipe designs suffer from galvanic corrosion due to the use of different materials for the retainer and the fuel filler pipe body, leading to premature corrosion of the outer pipe and decreased concentricity and roundness precision due to thermal strain from continuous welding.
Innovation Solution
The retainer is divided into two tube members, with the plated steel sheet forming the fuel filler pipe body located inside and the stainless steel retainer outside, using spot welding to minimize thermal strain and maintain airtightness, while the internal thread is protected from heat deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different materials (stainless steel retainer and plated steel sheet pipe body) are used to prolong vehicle life cycle and ensure anticorrosion performance, then the anticorrosion performance is improved, but galvanic corrosion occurs at the overlapping portion due to potential difference
Solution Approach 1:
The patent inverts the conventional material arrangement by placing the plated steel sheet pipe body inside the stainless steel retainer, reversing the typical outer-inner configuration. This inversion ensures that the plated steel sheet, which corrodes first due to galvanic corrosion, is positioned inside where it protects the stainless steel retainer, thereby maintaining airtightness even after corrosion occurs.
2Strength
If continuous welding is used to mount the retainer to the fuel filler pipe body, then the mounting strength is improved, but the retainer suffers thermal strain leading to decreased concentricity precision and roundness precision
Solution Approach 1:
The retainer is divided into two separate tube members (first tube member with internal thread and second tube member forming insertion hole) that are joined by spot welding rather than continuous welding. This segmentation reduces the total welding heat input and thermal strain on the retainer, thereby maintaining concentricity precision and roundness precision while still achieving sufficient mounting strength.
3Adaptability or versatility
If the retainer is made with internal thread for fuel cap connection and insertion hole for nozzle, then the functionality is improved, but the concentricity precision and roundness precision decrease due to thermal strain from continuous welding
Solution Approach 1:
The retainer is segmented into two tube members where the first tube member contains the internal thread and the second tube member contains the insertion hole. These members are joined by spot welding at specific locations, which minimizes thermal strain on the threaded and hole-forming portions, thereby preserving concentricity precision and roundness precision while maintaining full functionality.
Solution Approach 2:
Different portions of the retainer have different structural characteristics: the first tube member has internal threading for fuel cap connection, while the second tube member has an insertion hole for the nozzle. The spot welding is applied locally at specific positions rather than continuously, providing localized joining while preserving the precision of critical features in other areas.
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 enhances anticorrosion performance by ensuring the inner pipe corrodes first, maintains airtightness, and reduces thermal deformation, resulting in higher fabrication accuracy and reduced process costs.
Implementation Method 1
different materials are used as materials of the retainer and the fuel filler pipe body, this tends to cause galvanic corrosion of a portion of the fuel filler pipe in which the fuel filler pipe body and the retainer overlap each other due to the potential difference therebetween
Implementation Method 2
a large amount of heat is continuously applied to the outer circumferential surface of the retainer by continuous welding, and thus, the retainer tends to be thermally strained, thereby decreasing the concentricity precision and roundness precision
Implementation Method 3
the second tube member is inserted through an opening of the first tube member at the other end of the first tube member into the first tube member, and is spot welded to the first tube member
Data Source
AI summary
A fuel filler pipe offering high anticorrosion performance and high fabrication accuracy is provided. Specifically, a tubular fuel filler pipe body 2 made of a plated steel sheet has a fuel filler port 2a at one end thereof, and is connected at the other end thereof to a fuel tank 10. A short cylindrical retainer 3 made of stainless steel is mounted into the fuel filler port 2a, and includes first and second tube members 5 and 6 each having both open ends. An inner circumferential surface of a portion of the first tube member 5 near an opening thereof at one end thereof includes an internal thread 5a threadedly connected to an external thread C1 of a fuel cap C. The second tube member 6 is inserted through an opening of the first tube member 5 at the other end thereof into the first tube member 5, and is joined to the first tube member 5 before the internal thread 5a by resistance spot welding Sw. One of the open ends of the second tube member 6 in a direction opposite to a direction of insertion of the second tube member 6 forms an insertion hole 6a through which a nozzle G1 of a fuel filler gun G is inserted. A retainer 3 is fitted into the fuel filler pipe body 2 to allow insertion of an end portion of the fuel filler pipe body 2 near the fuel filler port 2a into a space S between an outer circumferential surface of a portion of the second tube member 6 near the insertion hole 6a and an inner circumferential surface of a portion of the first tube member 5 near the opening thereof at the other end thereof, and a portion of the retainer 3 fitted into the fuel filler pipe body 2 are continuously welded to the fuel filler pipe body 2 by brazing Tw.