Blood Circuit Access Port Valve Structure for Leak-Safe Syringe Locking
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Solution Overview
Problem
Existing access port members for blood circuits face issues with reliable sealing, ease of connection, and secure locking due to dimension errors in tapered surfaces and thread shapes, leading to potential leakage and difficulty in opening the slit valve.
Innovation Solution
An access port member design featuring a valve with a rib structure around the slit and a cap part with a thread shape where the terminal end thread height is higher than other portions, facilitating easy connection and secure locking, while preventing leakage and ensuring reliable sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve is made thicker to prevent difference in level in the slit, then the reliability of closing is improved, but the ease of operation deteriorates due to large pressing force required
Solution Approach 1:
The valve is divided into two distinct parts: a thick base portion that maintains structural integrity and prevents level differences in the slit, and a thin pressing portion that is easily deformable. This segmentation allows the valve to simultaneously achieve reliable closing (through the thick base) and ease of opening (through the thin pressing area) without requiring high pressing force.
2Reliability
If dimension error occurs in tapered surfaces, then the sealing performance deteriorates causing liquid leakage, but the ease of manufacture improves with standard tolerances
Solution Approach 1:
A rib structure is introduced as an intermediary element between the tapered surfaces of the cap part and syringe. This rib absorbs dimensional variations and errors in the tapered surfaces, maintaining effective sealing even when manufacturing tolerances are not tightly controlled. The rib acts as a compensating feature that ensures liquid-tight sealing without requiring high-precision manufacturing.
3Ease of operation
If the thread shape of locking part is smaller than set dimensions, then the ease of operation improves with easier screwing, but the reliability deteriorates due to loose connection
Solution Approach 1:
The locking part features non-uniform thread dimensions with different characteristics in different regions. The thread shape is designed to provide easy screwing in the initial stages while maintaining secure locking in the final position. This local variation in thread quality allows the locking mechanism to simultaneously achieve ease of operation and reliable connection security.
4Reliability
If the thread shape of locking part is larger than set dimensions, then the reliability improves with secure locking, but the ease of operation deteriorates due to tight screwing
Solution Approach 1:
The thread shape of the locking part is designed with spatially varying dimensions that provide different functional characteristics at different locations. This local quality variation enables the thread to offer reduced resistance during initial engagement (ease of screwing) while providing increased engagement and security at the final locked position (reliable connection).
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 enhances the ease of opening the slit valve without high pressing force, reduces stagnation points, and ensures secure sealing and locking, preventing leakage and blood clotting.
Implementation Method 1
Since the valve is made of an elastic member such as a rubber material, the closed state of the slit can be maintained by the elastic force.
Data Source
AI summary
An access port member includes: a body 8 to be connected to a predetermined portion of a blood circuit for causing a patient's blood to extracorporeally circulate, the body 8 internally including a flow path 8b for circulating the blood and having an opening 8c communicating with the flow path 8b; a valve 9 that is made of an elastic member covering the opening 8c and attached to an attachment part 8d of the body 8, the valve including a slit that makes a transition from a closed state to an open state when pressed by a tip 11a of a syringe 11 capable of collecting blood or injecting a drug; a cap part 10 fixed to the body 8 with the valve portion 9 interposed therebetween and the slit 9a facing outward; and a rib 9b formed integrally along the periphery of the slit 9a in the valve 9.