Fuel Filler Funnel Insert Sealing for Tolerance Gap Compensation
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Solution Overview
Problem
The existing funnel inserts for fuel tank filler tubes face challenges in accommodating dimensional tolerances of the filler tubes due to the need for a flexible fluid barrier, which is not adequately met by sealing lips made of dimensionally stable plastics materials like POM, as they cannot flexibly seal varying gap widths caused by production variations and material expansion/contraction.
Innovation Solution
A sealing body with a higher flexibility than the funnel insert material is integrated on the outer circumference, produced from a flexible plastics material such as HDPE with an elongation-at-break value over 50%, allowing for compensation of radial dimensional deviations up to ±5 mm, and can be manufactured separately or through a two-component injection molding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a sealing lip is made of dimensionally stable plastics material like POM, then the sealing body maintains dimensional stability and structural integrity, but it cannot flexibly seal varying gap widths caused by production tolerances and material expansion/contraction
Solution Approach 1:
The sealing body is segmented into two distinct material components: a dimensionally stable core structure (funnel insert made of POM) and a flexible sealing element (sealing lip made of HDPE with elongation-at-break >50%). This segmentation allows each part to perform its specialized function - the POM core maintains geometric stability while the HDPE lip accommodates gap variations through elastic deformation.
Solution Approach 2:
The sealing body utilizes composite construction by combining two plastics materials with complementary properties - POM (polyoxymethylene) for dimensional stability and HDPE (high-density polyethylene) with high elongation-at-break for flexibility. This composite approach enables the sealing body to simultaneously achieve structural integrity and adaptive sealing capability across varying gap widths of ±5 mm.
2Ease of manufacture
If the filler tube is produced from HDPE plastics material with dimensional tolerance, then production cost is reduced, but the gap size between the funnel insert and fill tube varies, requiring a more flexible fluid barrier
Solution Approach 1:
The solution changes the material parameter of the sealing lip from dimensionally stable (POM) to highly flexible (HDPE with elongation-at-break >50%). This parameter change enables the sealing lip to accommodate the ±5 mm gap variations resulting from HDPE filler tube production tolerances, maintaining effective sealing without requiring high-precision filler tube manufacturing.
3Reliability
If the funnel insert is produced from POM or other dimensionally stable plastics materials, then the misfuelling protection device functions reliably, but the material is not very flexible and cannot seal varying gap widths
Solution Approach 1:
The funnel insert applies local quality by using different materials for different functional zones: the main body (funnel insert) is made of POM to ensure reliable misfuelling protection device operation, while the sealing lip portion is made of flexible HDPE to accommodate gap variations. This local differentiation allows each zone to have the material properties optimal for its specific function.
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 solution ensures a reliable seal despite manufacturing tolerances and operational variations, preventing fuel backflow and ensuring long-term durability of the sealing body.
Implementation Method 1
the sealing body consists of a material having a higher flexibility than the material of the funnel insert... the sealing body is produced from a flexible plastics material... a high elongation-at-break value ensures that deformations, vibrations, displacements and the like occurring during assembly and operation do not damage the sealing body
Data Source
AI summary
A funnel insert for a filler tube of a fuel tank for a motor vehicle, the funnel insert being arranged in an end region of the filler tube intended to receive a fuel nozzle, and there being a space between the outside of the funnel insert and the inside of the filler tube, in which space a fluid barrier is arranged. According to the invention, the fluid barrier is in the form of a sealing body arranged on the outer circumference of the funnel insert, which sealing body comprises a sealing lip resting on the inside of the filler tube in portions or circumferentially, and consists of a material having a higher flexibility than the material of the funnel insert.