Autoinjector Plunger Clip for Axial and Radial Control
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Solution Overview
Problem
Automatic injection devices face challenges in limiting unwanted movement of components during manufacturing while allowing for minor displacement to account for manufacturing tolerances, ensuring proper operation and accurate delivery of therapeutic substances.
Innovation Solution
A plunger subassembly with a plunger body and rod, where the plunger rod includes a clip that limits axial displacement and radial deflection, integrated into a drug delivery device with a drive assembly and needle cover, allowing for precise movement and shielding of the needle during use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple component subassemblies are used in manufacturing, then device assembly flexibility is improved, but component movement and displacement control becomes more difficult
Solution Approach 1:
The plunger is divided into separate subassemblies (plunger rod and plunger body) that can be manufactured independently and then assembled together, improving manufacturing flexibility while maintaining control through the connecting clip structure
Solution Approach 2:
A clip structure serves as an intermediary element connecting the plunger rod and plunger body, providing a controlled interface that limits unwanted movement while allowing assembly of multiple components
2Ease of manufacture
If manufacturing tolerances are accommodated with minor displacement, then assembly ease is improved, but device operation reliability may be compromised
Solution Approach 1:
The clip structure is designed with specific dimensional parameters that allow for controlled displacement within manufacturing tolerances while maintaining reliable operation through its geometric constraints
3Adaptability or versatility
If plunger rod is made flexible to accommodate tolerances, then assembly flexibility is improved, but radial deflection control becomes problematic
Solution Approach 1:
The plunger rod has different structural properties at different locations - it is flexible enough to accommodate tolerances in certain areas while being constrained by the clip structure in critical areas to prevent excessive radial deflection
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 ensures accurate and safe delivery of therapeutic substances by limiting unwanted movement of components, maintaining device functionality, and providing a secure needle shielding mechanism.
Implementation Method 1
the clip is configured to be received within the opening of the plunger body head and to limit axial displacement between the plunger rod and the plunger body
Implementation Method 2
the clip is configured to be received within the opening of the plunger body head and to limit axial displacement between the plunger rod and the plunger body, and to limit radial deflection of the plunger rod
Data Source
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AI summary
Provided herein is a plunger subassembly for a drug delivery device, including a plunger body having a proximal end, a distal end, and a sidewall therebetween, the plunger body comprising a head at the proximal end thereof, the head defining a passage therethrough, and a plunger rod having a proximal end and a distal end, the plunger rod comprising a clip at the proximal end thereof, wherein the clip is configured to be received within the opening of the plunger body head and to limit axial displacement between the plunger rod and the plunger body, and to limit radial deflection of the plunger rod.