Readily Burstable Slide Fastener for Inflatable Lifejackets
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Solution Overview
Problem
Conventional hook-and-loop surface fasteners used in inflatable lifejackets and liferafts suffer from wear and tear, and performance degradation due to exposure to water, especially in marine environments, and can be problematic in freezing conditions, while conventional slide fasteners cannot be easily burst open.
Innovation Solution
A readily burstable slide fastener design featuring a first and second stringer with coupling elements and a slider that automatically opens along its length under inflating pressure, incorporating weakened regions or modified coupling elements to facilitate automatic separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hook-and-loop surface fastener is used to secure the covering, then the fastener can be easily separated by pulling, but the adhesive force decreases over time due to wear and tear and water exposure
Solution Approach 1:
The patent applies this principle by making the coupling elements at the weakened region sacrificial - they are designed to fail first and are replaced automatically during the bursting process. The bulk of the coupling elements remain intact and reusable, while only the localized weakened region elements are consumed, providing a cost-effective solution to the wear and tear problem.
Solution Approach 2:
The patent segments the coupling elements into two functional groups: durable coupling elements that remain intact for repeated use, and sacrificial coupling elements at the weakened region that are designed to fail first. This segmentation allows the fastener to maintain reliability through the durable elements while providing easy separation through the sacrificial elements that burst under inflation pressure.
2Reliability
If a conventional slide fastener is used, then the fastener maintains strength and resists water, but it cannot be easily burst open at a point along its length
Solution Approach 1:
The patent applies local quality by creating a weakened region with modified coupling elements at a specific location along the slide fastener, while the rest of the coupling elements remain strong and durable. This localized modification allows the fastener to maintain overall strength and water resistance while providing a specific point that can be easily burst open under inflation pressure.
Solution Approach 2:
The patent prepares the weakened region in advance during manufacturing, with coupling elements that are pre-modified to have reduced strength. This preliminary action ensures that when inflation pressure is applied, the fastener will burst at the predetermined weakened region rather than requiring forceful manual opening, thus maintaining both durability and ease of operation.
3Reliability
If the slide fastener is made strong to prevent premature opening, then reliability is improved, but the fastener cannot automatically open under inflation pressure
Solution Approach 1:
The patent creates a localized weakened region with modified coupling elements that have different mechanical properties from the strong coupling elements. The strong elements prevent premature opening under normal conditions, while the weakened elements are designed to fail at a specific inflation pressure, enabling automatic opening without compromising overall reliability.
Solution Approach 2:
The patent changes the mechanical parameters (strength, stiffness) of the coupling elements in the weakened region compared to the rest of the fastener. This parameter differentiation allows the fastener to maintain high reliability through the strong elements while the weakened elements automatically fail at a predetermined pressure threshold, achieving both reliability and automation.
4Reliability
If the coupling elements are made durable against water and wear, then the fastener maintains effectiveness over time, but it cannot be easily separated when needed
Solution Approach 1:
The patent segments the coupling elements into durable elements that resist water and wear for long-term reliability, and sacrificial weakened elements that are easily separated under inflation pressure. This segmentation resolves the contradiction by assigning different functional requirements to different portions of the fastener system.
Solution Approach 2:
The patent applies this principle to the weakened region coupling elements, which are designed as sacrificial components that fail first during bursting. These elements are replaced automatically during the bursting process, while the durable coupling elements remain intact for repeated use, providing a cost-effective solution to the durability versus ease of separation contradiction.
Data Source
AI summary
A readily burstable slide fastener for an inflatable device, such as a lifejacket, that includes a first stringer, a second stringer and a slider slidably mounted on the second stringer. At a weakened region along the slide fastener coupling elements are omitted from each of the stringers so that when a bursting force is applied to this region the coupling elements adjacent thereto are disengaged. The coupling elements are omitted from the top of the first stringer so that when the slider is at the top of the coupling elements of the second stringer, the first stringer can disengage from the slider. When the slide fastener is fitted to an inflatable lifejacket, the stringers are separated completely when the lifejacket is inflated.