Syringe Cap Assembly Pressure Management
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Solution Overview
Problem
The existing syringe assembly designs face issues with the cap detaching due to excessive positive pressure in the closed space between the cap and the barrel tip, especially during sterilization processes, which complicates the assembly and maintenance of pre-filled syringes.
Innovation Solution
A method and assembly device that discharge gas from the closed space before sealing the needle hole, reducing the pressure to equal or lower than atmospheric pressure, facilitating easy cap mounting and preventing detachment, including configurations that ensure the pressure remains below 80 kPa or 60 kPa during specific sterilization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the barrel tip is inserted into the receiving hole to seal the closed space, then the needle hole is sealed and the puncture needle is protected, but excessive positive pressure is generated in the closed space causing the cap to detach
Solution Approach 1:
A gas discharge hole is formed in the bottom wall of the receiving hole to discharge gas from the closed space before the needle hole is sealed. This preliminary gas discharge prevents excessive positive pressure buildup that would cause cap detachment, while still allowing the subsequent sealing operation to protect the puncture needle.
Solution Approach 2:
The bottom wall of the receiving hole is segmented to include both a gas discharge hole for pressure relief and a stopper for positioning. This segmentation allows the closed space to vent gas during assembly while maintaining structural integrity for sealing and protection functions.
2Reliability
If the closed space is sealed to protect the puncture needle from bacteria, then liquid-tight filling is achieved, but the assembly process becomes complex due to pressure management requirements
Solution Approach 1:
The gas discharge hole is pre-formed in the bottom wall of the receiving hole, enabling automatic pressure equalization during the assembly process. This eliminates the need for separate pressure management steps, simplifying the overall assembly process while maintaining protection reliability.
Solution Approach 2:
The gas discharge hole automatically vents gas from the closed space during cap assembly without requiring external intervention. The system self-regulates the pressure, making the assembly process simpler while ensuring reliable sealing and protection.
3Ease of operation
If gas is discharged from the closed space before sealing, then cap mounting is facilitated and detachment is prevented, but the sealed space must be resealed after discharge
Solution Approach 1:
The bottom wall is segmented into a gas discharge hole for pressure relief and a stopper for positioning. This allows gas discharge during assembly while maintaining a simple integrated structure that automatically seals after the puncture needle tip blocks the discharge hole.
Solution Approach 2:
The gas discharge hole automatically stops functioning as a discharge path when the puncture needle tip inserts into the receiving hole and blocks it. The system self-seals without requiring additional sealing operations, simplifying the overall process.
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 solution effectively prevents cap detachment and simplifies the assembly process by maintaining a reduced pressure state, ensuring secure cap attachment and reliable operation during sterilization and cleaning procedures.
Implementation Method 1
a closed space having an internal pressure lower than an external pressure
Data Source
Figure 1
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AI summary
The present invention relates to a method and an assembly device for assembling an assembly (10) for a syringe. A method for assembling the assembly (10) for a syringe according to the present invention includes: a closed space forming process in which a puncture needle (14) and a barrel tip (18) of an outer barrel (12) are inserted into a receiving hole (34) of a cap (16) to form a closed space (62) enclosed by the receiving hole (34) and the barrel tip (18) before a tip end of the puncture needle (14) is inserted into a bottom wall (36) of the receiving hole (34); a gas discharge process of discharging gas in the closed space (62) through a needle hole (32) and an inner space (20), which is formed in the outer barrel (12) so as to communicate with the needle hole (32); and a sealing process of sealing the tip end of the needle hole (32) by further inserting the barrel tip (18) into the receiving hole (34) to insert the tip end of the puncture needle (14) into the bottom wall (36).