Gasket Biasing Assembly for Reliable Prefilled Syringe Release
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Solution Overview
Problem
Existing prefilled syringes face challenges with high injection resistance, especially for viscous liquids, and the engagement between the piston rod and connector is prone to premature release, making self-administration and medical administration difficult.
Innovation Solution
A gasket biasing member assembly that includes a gasket pressing member, a biasing member, and an operating member, which allows for stable retention of biasing force until use and easy release during administration, facilitating the discharge of liquid medicine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spring is used to bias the piston rod toward the distal end, then injection resistance is reduced and self-administration becomes easier, but the engagement between the piston rod and connector is prone to premature release
Solution Approach 1:
The piston rod incorporates a deflectable latch that can dynamically change state between engaged and disengaged positions. The latch is biased by a spring to maintain engagement during storage and transport, but can be easily deflected to the disengaged position when needed for administration, allowing the system to adapt between stability and ease of operation.
Solution Approach 2:
The engagement structure is pre-configured with the deflectable latch in a predetermined engaged state that provides sufficient opposing force against the spring bias before use. This preliminary engagement state ensures reliability during storage while allowing easy transition to the active state when needed.
2Reliability
If the engagement between piston rod and connector is strengthened to prevent premature release, then reliability is improved, but it becomes difficult to release the engagement during use
Solution Approach 1:
The deflectable latch provides asymmetric engagement characteristics: it presents a stable engaged state with high opposing force that is difficult to disengage accidentally, but includes a defined deflection path that allows easy intentional release when needed, resolving the contradiction between retention strength and release ease.
Solution Approach 2:
The engagement interface uses locally differentiated properties where the deflectable latch has different mechanical characteristics at different positions and directions - strong resistance to forces attempting to disengage it prematurely, but easy deflection along the specific release path when intentionally activated.
3Power
If a biasing member is compressed to store energy for liquid discharge, then discharge power is improved, but the mechanism becomes more complex
Solution Approach 1:
The spring biasing member is integrated directly into the piston rod structure, with the spring housed within or attached to the piston rod assembly. This merging of the biasing mechanism with the moving component eliminates the need for separate housing structures and simplifies the overall device while maintaining the power delivery function.
Solution Approach 2:
The spring biasing member serves multiple functions simultaneously: it stores energy for power delivery during discharge, provides continuous biasing force to maintain engagement of the piston rod with the connector, and contributes to the overall structural integrity of the assembly, reducing the need for additional dedicated components.
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 assembly ensures reliable and easy discharge of liquid medicine by maintaining biasing force until needed, simplifying self-administration and medical administration by providing a stable and controllable mechanism for gasket movement.
Implementation Method 1
a biasing member (6) arranged in a compressed state between the gasket pressing member (5) and the flange attachment member (7)
Data Source
Figure 1
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Figure 3
AI summary
A liquid medicine administration device 1 includes a prefilled syringe 10 and a gasket biasing member assembly 20. The biasing member assembly includes: a gasket pressing member 5 that presses a gasket 3; a flange attachment member 7 attached to the prefilled syringe; a biasing member 6 housed between the pressing member and the flange attachment member; and an operating member 9 including an engagement holding portion 93. The pressing member 5 includes an engagement portion 541 to be engaged with the flange attachment member, the engagement portion 541 includes an abutment portion 542, and deformation is regulated by receiving an engagement state holding portion, and an engagement state between the engagement portion 541 and the flange attachment member 7 is held.