Piston Extension Rod for Vacuum-Free Injector Mounting
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Solution Overview
Problem
Existing methods for mounting pistons in prefilled syringes face challenges such as damage to sensitive biologics due to vacuum mounting, residual air, and incompatibility with silicone-free applications, especially in scenarios with small fill volumes and high vacuum requirements, which can lead to drug exposure and inefficiency.
Innovation Solution
A novel piston mounting method using a piston extension rod that impacts the piston cavity base at a velocity of at least 25 mm/min, causing the deformable sealing element to contract and create a bypass for air, allowing the piston to move closer to the drug surface without vacuum, reducing friction and residual air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum mounting is used to position the piston, then the piston can be positioned with minimal residual air, but the high vacuum requirements can cause damage to the drug through temperature increase and boiling
Solution Approach 1:
The patent replaces the vacuum system with a mechanical piston extension rod system. The extension rod is inserted through the piston cavity opening and impacts the piston cavity base to extend the piston along the cylinder axis, creating a bypass for air without requiring vacuum. This mechanical approach eliminates the harmful thermal effects of vacuum while achieving precise piston positioning.
Solution Approach 2:
The piston extension rod acts as an intermediary mechanism between the mounting system and the piston. Instead of directly applying vacuum force to the piston, the extension rod mechanically extends the piston through impact, mediating the positioning process and eliminating the need for vacuum while achieving the desired piston position with minimal residual air.
2Manufacturing precision
If vent-tubing is used for piston mounting, then the piston can be forced into the correct position, but the method causes damage to piston sealing elements and PTFE coating due to excess friction and temperature increase
Solution Approach 1:
The patent replaces the vent-tubing mechanical compression system with a piston extension rod system. The extension rod enters the piston cavity opening and impacts the piston cavity base, extending the piston along the cylinder axis without the severe compression and friction of vent-tubing. This eliminates damage to sealing elements and PTFE coating while maintaining positioning accuracy.
Solution Approach 2:
Instead of compressing the piston from the outside through vent-tubing, the invention extends the piston from the inside through the piston cavity opening. The extension rod impacts the piston cavity base and extends the piston along the cylinder axis, inverting the traditional compression approach and eliminating the harmful friction and temperature effects.
3Manufacturing precision
If assisted vacuum mounting is used for small fill volumes, then the piston can be drawn to the intended position, but the combination requires high vacuum which exposes the drug to excess temperature
Solution Approach 1:
The patent replaces the assisted vacuum mounting system with a mechanical piston extension rod system. The extension rod is inserted through the piston cavity opening and impacts the piston cavity base to extend the piston along the cylinder axis, creating a bypass for air. This mechanical approach eliminates the need for high vacuum and its associated thermal effects on the drug, while achieving precise piston positioning for small fill volumes.
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 method enables precise piston positioning with minimal residual air, reduces friction and stress on sealing elements, increases mounting speed, and eliminates the need for vacuum systems, resulting in lower power consumption and higher output per unit time.
Implementation Method 1
impacting the piston cavity base with the impact surface at a velocity of at least 25 mm/min to extend the piston along the cylinder longitudinal axis
Implementation Method 2
cause a contraction of the deformable sealing element to create a bypass of air in the space between the piston and the drug upper surface
Implementation Method 3
cause a contraction of the deformable sealing element to create a bypass of air in the space between the piston and the drug upper surface
Data Source
AI summary
The present invention relates to a Piston Extension Rod (1) for piston mounting in an injector, which injector comprises a container having a longitudinal axis and an inner wall, and a piston (3) with elastomeric properties having a cavity (10) with an opening (22) and a base (20) and a deformable sealing element (11), which deformable sealing element abuts the inner wall of the cylinder (13) and seals an annular gap between the piston and the inner wall of the cylinder, said piston extension rod has a total length of at least 5% more than the total cavity length of said piston measured from the piston cavity base 20 to the piston cavity opening (22), said piston extension rod for positioning of said piston accelerates towards the container outlet end and enters the piston cavity (10) said piston extension rod impact surface 19 impacting with the piston cavity base (20) during accelerated movement of at least 25 mm/min so that during said impact between piston extension rod and piston the impact and continuous velocity in the direction of the container outlet end causes the piston to extend in the container longitudinal axis resulting in a contraction of the piston deformable sealing element (11) perpendicular to the container longitudinal axis eliminating said sealing element's contact with the container inner wall allowing for bypass of air (14) in the space between the piston and the liquid drug (23), said contraction to cease at final piston positioning resulting in reestablishment of the piston sealing against the container inner wall.