Capless Fuel Filler Closure With Spring-Loaded Flapper Sealing

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing fuel tank filler systems require a cap that needs to be removed and replaced during refueling, leading to potential spillage and inconvenience.

Innovation Solution

A capless filler pipe closure system with pivotable flapper doors and torsion springs that automatically open and close to allow the fuel nozzle to enter and exit, ensuring a sealed connection without a physical cap.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a traditional cap system is used to seal the filler pipe, then the filler pipe can be sealed when not in use, but the cap needs to be manually removed and replaced during refueling which causes potential spillage and inconvenience

Engineering Contradiction:
Improverefueling operation convenienceVSAvoidsealing reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The flapper door assembly automatically opens when the fuel nozzle is inserted and automatically closes when the nozzle is removed, eliminating the need for manual cap handling. The system serves itself by using the nozzle insertion motion to trigger the opening mechanism and spring force to close the door, preventing spillage and improving convenience simultaneously

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The flapper door transitions from a static cap to a dynamic component that moves between open and closed positions based on nozzle insertion. The door is hinged to allow rotation and is equipped with spring mechanisms that provide automatic opening and closing motion, adapting the sealing state to operational requirements

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If a capless system with flapper doors is used, then refueling convenience is improved, but the complexity of the closure mechanism increases

Engineering Contradiction:
Improverefueling operation convenienceVSAvoidclosure mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The closure system is divided into separate functional components: the flapper door, the hinged mounting mechanism, the spring assembly, and the nozzle-receiving aperture. Each component performs a specific function and can be independently analyzed or maintained, reducing the perceived complexity despite the automated functionality

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spring mechanism acts as an intermediary that translates nozzle insertion motion into door opening action and automatically restores the closed position. This intermediary component simplifies the control logic by using mechanical energy storage and release rather than requiring electronic sensors or actuators

Inventive Principle:
Principle #24Intermediary (Mediator)

3Extent of automation

If flapper doors are used to seal the nozzle-receiving aperture, then automatic opening and closing is achieved, but the door-closing spring must be mounted on a separate pin from the door-support pin

Engineering Contradiction:
Improveautomatic door operationVSAvoidmounting structure complexity
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The spring mounting function is extracted from the door support structure and placed on a separate pin. This separation allows the spring to be independently positioned and adjusted without interfering with the door's hinged motion, simplifying the overall mounting architecture despite the additional component

Inventive Principle:
Principle #2Taking out (Extraction)

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

Provides a convenient and spill-proof refueling process by maintaining a sealed connection between the fuel nozzle and filler pipe, enhancing user experience and safety.

Implementation Method 1

a door-closing spring arranged to apply a door-closing force to the flapper door and pivot the flapper door about the door-pivot axis to close the nozzle-receiving aperture

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

Each door-closing spring is mounted on a spring-support pin that is included in the nozzle-insertion housing and separated from its companion door-support pin

Methodology Applied
Scientific EffectTorsion Spring: Torsion Spring

Data Source

PatentEP3969313B1Capless closure assembly for fuel-tank filler pipe
Publication Date: 2026.01.21 STANT USA CORP
  • EP3969313B1 patent drawingFigure 1~2
  • EP3969313B1 patent drawingFigure 3
  • EP3969313B1 patent drawingFigure 3A

AI summary

A capless filler pipe closure is provided for a tank filler pipe. The capless closure permits a fuel pump nozzle to be inserted into the tank filler pipe without first removing a fuel cap from the outer end of the tank filler pipe.