Medical Fluid Container Sealing Plug with Radial Lips
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Solution Overview
Problem
Existing medical fluid containers with screw cap seals face issues with irregularities in manufacturing, leading to leaks and reduced sealing effectiveness due to insufficient precision in sealing surfaces, especially after sterilization, where the tightening torque is reduced, and the sealing ring breaks at a larger opening distance than necessary, allowing fluid to escape before the primary seal is compromised.
Innovation Solution
A medical fluid container design featuring a closure cap with a sealing plug and radially protruding sealing lips that form a primary seal within the container connection piece's inner channel, ensuring the container remains sealed until the sealing ring breaks, and an additional sealing lip that maintains sealing even when the cap is partially unscrewed, preventing fluid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extrusion blow molding is used to manufacture the container connection piece, then production efficiency is improved, but the sealing surface precision deteriorates
Solution Approach 1:
The sealing system is segmented into multiple independent sealing elements: a primary sealing ring at the end face and a secondary sealing lip on the inner channel. This segmentation allows each sealing element to address specific sealing requirements independently, compensating for the imprecision of extrusion blow molding while maintaining high production efficiency.
Solution Approach 2:
The patent incorporates a recess in the sealing surface of the container connection piece that accommodates the sealing lip. This pre-designed feature compensates for potential irregularities in the extrusion blow molding process, ensuring reliable sealing contact is maintained despite variations in manufacturing precision.
2Reliability
If the container is sterilized at high temperature, then sterilization effectiveness is improved, but the tightening torque and sealing contact force deteriorate
Solution Approach 1:
The patent uses elastomeric materials for both the sealing ring and sealing lip that maintain their sealing properties across a wide temperature range. These materials are selected to resist thermal degradation during sterilization, ensuring that sealing effectiveness is maintained even when tightening torque reduces due to thermal expansion and material softening.
Solution Approach 2:
The recess accommodating the sealing lip provides a mechanical stop that ensures consistent sealing contact. This geometric constraint compensates for thermal effects during sterilization, maintaining reliable sealing despite changes in tightening torque caused by temperature-induced material property changes.
3Reliability
If the sealing ring is positioned to break at large opening travel, then tamper evidence is improved, but fluid leakage risk increases before seal failure
Solution Approach 1:
The sealing system is divided into two stages: a primary sealing ring that provides immediate sealing and a secondary sealing lip as backup. This segmentation ensures that if the cap is partially unscrewed, the secondary sealing lip maintains the seal, preventing fluid leakage even when the primary seal is compromised, while the sealing ring still breaks at full opening to provide tamper evidence.
Solution Approach 2:
The secondary sealing lip acts as a backup sealing mechanism that engages if the primary seal fails or is compromised during partial opening. This redundant sealing arrangement prevents fluid leakage before the sealing ring breaks, eliminating the harmful effect while preserving the tamper-evident 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
The design ensures the fluid container remains sealed until the sealing ring breaks, preventing premature leakage and maintaining a high sealing effect during sterilization and storage, while the additional sealing lip ensures the container remains sealed even when the cap is not completely screwed on, addressing manufacturing irregularities and temperature-induced shape changes.
Implementation Method 1
The elasticity of the sealing insert and the fluid container makes it possible to assemble the two components despite the dimensional overlap
Implementation Method 2
If the shape of the thread changes under the influence of the sterilization temperature, this can lead to a loss or reduction of the tightening torque
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A medical fluid container (1) comprising: a container connection fitting (4) forming an inner channel (6), through which the interior of the container is accessible from the outside and which has an external thread (10) on a longitudinal section (8) of the fitting, and a sealing cap (2) which is screwed onto the longitudinal section (8) of the fitting by means of an internal thread (12) to close the fluid container (1) and which has a sealing insert (14) with a sealing plug (16) which projects into the inner channel (6) of the container connection fitting (4) such that a circumferential surface of the sealing plug (16) is in sealing contact with an inner surface of the inner channel (6). One or more axially spaced circumferential sealing lips (24) project radially outwards from the circumferential surface of the sealing plug (16).