Piston with Longitudinal Relief Channel for Injection Kit
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Solution Overview
Problem
Current re-usable injection kits for dental anesthesia face risks of operator injury during needle recapping and malfunction due to trapped drug residue preventing snap-action coupling, and the production of relief channels is hindered by mold burrs from die slides.
Innovation Solution
A piston with a co-moulded core and deformable coating, featuring a longitudinal cavity with progressive diameter reduction and strategically placed through openings at the axial end, allowing fluid communication and bypass of residual liquid, eliminating the need for die slides and reducing the risk of occlusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transverse relief channel is provided in the axial extension of the piston to allow evacuation of trapped liquid, then the coupling by snap action can occur, but the channel requires die slides in mould production which create burrs that may occlude the channel
Solution Approach 1:
The invention changes the orientation of the relief channel from transverse to longitudinal, aligning it with the axial direction of the piston. This dimensional reorientation eliminates the undercut geometry that necessitates die slides, allowing direct mould removal without burr formation, thus preventing channel occlusion while maintaining liquid evacuation functionality
Solution Approach 2:
The invention modifies the geometric parameters of the relief channel by changing its orientation angle from transverse (perpendicular to axis) to longitudinal (parallel to axis). This parameter change fundamentally alters the moulding process requirements, eliminating the need for complex die slide mechanisms and associated burr problems
2Object-affected harmful factors
If manual capping of the needle is performed to de-risk it, then the needle is protected, but the operator is exposed to high risk of injury
Solution Approach 1:
The system performs self-protection by automatically encapsulating the needle within the tubular vial through the piston's axial extension coupling with the needle. This self-service mechanism eliminates the need for manual intervention, allowing the system to de-risk the needle hazard autonomously without exposing the operator to injury
Solution Approach 2:
The axial extension of the piston acts as an intermediary element that couples the piston mechanism to the needle, enabling automatic needle encapsulation. This intermediary component transfers the protective function from manual operation to automated system action, reducing operator exposure to hazards
3Reliability
If the piston is retracted to draw the needle within the tubular vial, then the needle is safely encased, but trapped liquid prevents coupling by snap action
Solution Approach 1:
The invention extracts the harmful element (trapped liquid) from the coupling zone by providing a longitudinal relief channel that allows the liquid to evacuate during the piston retraction process. This extraction of the obstructing liquid enables the axial extension to successfully couple with the needle by snap action, facilitating reliable needle encapsulation
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
Ensures safe encapsulation of the needle without manual interaction, prevents malfunction by facilitating complete evacuation of residual liquid, and simplifies production by avoiding mold burrs, thus enhancing safety and usability of the injection kit.
Implementation Method 1
a coating portion S made of deformable and/or elastomeric plastic material
Implementation Method 2
provision of a relief or by-pass channel extending in a direction transverse to the longitudinal axis of the piston and passing through it
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Described herein is a piston (1) for a tubular vial (100), comprising: - a longitudinal axis (X1); - a skirt (2) with axis coinciding with said longitudinal axis (X1) and configured for guiding the piston along an inner surface (102B) of a tubular vial (100); and an axial extension (4) comprising an axial cavity (6P) and including an outer surface (4A) and an inner surface (4B), the inner surface (4B) facing said axial cavity (6P), wherein: said axial extension (4) comprises at least one through opening (26) extending from said outer surface (4A) to said inner surface (4B); the intersection of said at least one through opening (26) with said outer surface (4A) presents an open perimeter; and the intersection of said at least one through opening (26) with said inner surface (4B) presents an open perimeter. Moreover described are a tubular vial (100) incorporating said piston (1) and a corresponding injection kit (200).