Nested Child-Resistant Closure With Spring Biasing and Venting Ribs
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Solution Overview
Problem
Existing child-resistant closures for containers are not sufficiently secure against accidental removal by children, as they can be unscrewed unintentionally due to the design of the drive mechanism and lack of effective venting features.
Innovation Solution
A child-resistant closure design featuring nested outer and inner caps with spring members, ramps, and castellations that provide a biasing force for screwing but allow unscrewing only with downward pressure, along with full height axial ribs for venting, ensuring the caps remain securely locked until intentional removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the closure uses a simple screw mechanism, then it is easy to manufacture and operate, but it can be accidentally removed by children
Solution Approach 1:
The closure employs dynamic spring members that change state based on applied force. During normal operation, the springs maintain a biased position that prevents accidental removal. When intentional removal is required, sufficient force overcomes the spring bias to enable unscrewing. This dynamic response to different force levels resolves the contradiction between ease of operation and child resistance.
Solution Approach 2:
The closure mechanism changes its mechanical parameters (spring compression, engagement force) based on the direction and magnitude of applied force. The spring members provide high resistance to unscrewing motion under normal conditions but allow movement when sufficient force is applied. This parameter change enables the closure to be easy to apply while resisting accidental removal by children.
2Reliability
If the closure uses a secure locking mechanism, then child resistance is improved, but the complexity of the device increases
Solution Approach 1:
The closure design nests the inner cap within the outer cap, with the spring members and drive formations integrated into the nested structure. The inner cap's drive formations (castellations) engage with the outer cap's spring members, creating a compact nested mechanism that provides secure locking without excessive complexity. This nesting approach resolves the contradiction between child resistance and device complexity.
Solution Approach 2:
The closure mechanism is segmented into distinct functional components: spring members for biasing and engagement, castellation drive formations for rotational coupling, and venting ribs for pressure management. Each segment performs a specific function, allowing the complex child-resistant mechanism to be broken down into manageable, purposeful elements that collectively achieve the desired reliability.
3Reliability
If the closure is designed to prevent accidental removal, then safety is improved, but venting capability may be compromised
Solution Approach 1:
The closure incorporates venting ribs at specific locations on the outer cap's side skirt, creating localized venting pathways that do not interfere with the child-resistant locking mechanism. These ribs provide targeted pressure relief while maintaining the integrity of the spring member and castellation engagement system. This local quality approach resolves the contradiction between child resistance and venting capability.
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
The design effectively prevents accidental removal by children, providing a secure locking mechanism that requires additional effort for unscrewing and includes venting features to manage pressure, enhancing safety and usability.
Implementation Method 1
the outer cap comprising a plurality of spring members for urging the inner and outer caps axially away from each other to a second axial position
Implementation Method 2
slipping over the ramps freely in an unscrewing direction
Data Source
Figure 1~2
Figure 3~4
Figure 5~9
AI summary
A child-resistant closure for a container is provided. The closure comprises outer (15) and inner (25) nested caps each having a top panel (16) and a side skirt (17) depending generally peripherally therefrom. The outer cap loosely generally encompasses said inner cap to allow relative rotary and axial movement therebetween. The outer and inner caps having corresponding drive formations which can be brought into driving engagement when the caps are moved axially towards one another to a first axial position. The outer cap comprises a plurality of spring members (18) for urging the inner and outer caps axially away from each other to a second axial position. The inner cap comprises a top panel provided with a plurality of ramps (30), the spring members providing a biasing force to maintain said outer and inner caps in the second axial position and drivingly engaging the ramps in the second axial position so as to drive the outer and inner caps together in a screwing direction, but slipping over the ramps freely in an unscrewing direction. Downward pressure on the outer cap is used to overcome the spring finger bias to move the caps to the first axial position to allow unscrewing of the closure using the inner and outer cap drive formations. The external surface of the inner cap side skirt includes a plurality of substantially full height axial ribs (20) for allowing venting when the outer and inner caps are initially assembled together. The inner cap drive formations comprise a plurality of castellations 34 which upstand from the inner cap top panel, and each full height axial rib connects to a castellation.