Non-linear Spring Mechanism for Vehicle Fueling Access Doors
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Solution Overview
Problem
Pivot and spring assemblies in vehicle fueling systems require high forces to open access doors and are prone to degradation from corrosive fluids, leading to performance issues.
Innovation Solution
A bar linkage mechanism with a first spring arm coupled to a second pivotable spring arm via a living spring hinge, where the second pivotable spring arm has lower stiffness, and both arms are made of non-corrosive materials like plastic, allowing for non-linear resistance and reduced exposure in corrosive environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pivot and spring assembly is used to mount access doors, then the door can be adjusted between open and closed positions, but a large applied force is required when the door has a large sealing force
Solution Approach 1:
The spring mechanism parameters (stiffness, pre-load, arm lengths) are specifically designed to provide a non-linear force-displacement response. The mechanism generates high force at small displacements to overcome sealing forces, then transitions to lower force at larger displacements to facilitate easy door opening. This parameter optimization resolves the contradiction between maintaining sealing force and reducing opening force.
Solution Approach 2:
The spring mechanism dynamically adapts its force output based on the door's position and sealing contact. As the door moves from closed to open position, the spring's effective stiffness changes, providing maximum force when needed to break the seal, then reducing force to assist smooth opening. This dynamic behavior resolves the contradiction between sealing reliability and ease of operation.
2Ease of operation
If a spring assembly is attached to access doors, then the door can be actuated, but the assembly is exposed to corrosive fluids that degrade and reduce lifespan
Solution Approach 1:
The spring mechanism is extracted from direct exposure to corrosive fluids by positioning it in protected locations away from fuel contact zones. The mechanism is integrated into the door assembly structure, with components located in areas not subject to fluid infiltration. This extraction protects the spring assembly from corrosion while maintaining door actuation functionality.
Solution Approach 2:
The spring mechanism utilizes corrosion-resistant materials and coatings to withstand the corrosive environment. Components are made from stainless steel, corrosion-resistant alloys, or are coated with protective layers that prevent fluid degradation. This material selection enables the mechanism to maintain reliability and lifespan despite exposure to corrosive fluids.
3Device complexity
If a linear spring mechanism is used, then the structure is simple, but the force-displacement response is linear requiring large force for doors with large sealing force
Solution Approach 1:
The spring mechanism employs dynamic geometric relationships where the effective spring rate changes with door position. As the door opens, the mechanism's geometry transitions, causing the spring to operate at different points on its force-displacement curve. This creates a non-linear response that provides high initial force to overcome sealing, then reduces force for easy opening, achieving this without complex additional components.
Solution Approach 2:
The spring arms and mounting geometry incorporate curved paths and non-linear kinematic relationships. The pivot points and attachment locations are positioned to create a mechanical advantage that varies with door angle, generating a non-linear force output from the spring. This geometric curvature enables the non-linear force-displacement response while maintaining relatively simple mechanism structure.
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
Enables access doors to open with less applied force and maintains performance in corrosive environments by providing non-linear resistance and resisting degradation from corrosive fluids.
Implementation Method 1
the first spring arm and second pivotable spring arm of the linkage mechanism may bend to produce an adequate non-linear resistance force that allows the element to open with less applied force
Data Source
AI summary
Methods and systems are provided for a non-linear spring mechanism coupled to a cover element. As an example, a system may comprise: a bar linkage mechanism having a first spring arm coupled to a second pivotable spring arm via a living spring hinge, the second pivotable spring arm having a lower or an equivalent stiffness compared to the first spring arm; an element coupled to at least one of the arms of the bar linkage mechanism. In one example, the element may be a cover cap, swing door or a sliding door. In this way, the linkage mechanism may allow the element to open with ease while providing improved performance in corrosive environments.